The scope and limits of top-down attention in unconscious visual processing

Attentional selection plays a critical role in conscious perception. When attention is diverted, even salient stimuli fail to reach visual awareness. Attention can be voluntarily directed to a spatial location or a visual feature for facilitating the processing of information relevant to current goals. In everyday situations, attention and awareness are tightly coupled. This has led some to suggest that attention and awareness might be based on a common neural foundation, whereas others argue that they are mediated by distinct mechanisms. A body of evidence shows that visual stimuli can be processed at multiple stages of the visual-processing streams without evoking visual awareness. To illuminate the relationship between visual attention and conscious perception, we investigated whether top-down attention can target and modulate the neural representations of unconsciously processed visual stimuli. Our experiments show that spatial attention can target only consciously perceived stimuli, whereas feature-based attention can modulate the processing of invisible stimuli. The attentional modulation of unconscious signals implies that attention and awareness can be dissociated, challenging a simplistic view of the boundary between conscious and unconscious visual processing.     

Brain-Stimulation Induced Blindsight: Unconscious Vision or Response Bias?

A dissociation between visual awareness and visual discrimination is referred to as “blindsight”. Blindsight results from loss of function of the primary visual cortex (V1) which can occur due to cerebrovascular accidents (i.e. stroke-related lesions). There are also numerous reports of similar, though reversible, effects on vision induced by transcranial Magnetic Stimulation (TMS) to early visual cortex. These effects point to V1 as the “gate” of visual awareness and have strong implications for understanding the neurological underpinnings of consciousness. It has been argued that evidence for the dissociation between awareness of, and responses to, visual stimuli can be a measurement artifact of the use of a high response criterion under yes-no measures of visual awareness when compared with the criterion free forced-choice responses. This difference between yes-no and forced-choice measures suggests that evidence for a dissociation may actually be normal near-threshold conscious vision. Here we describe three experiments that tested visual performance in normal subjects when their visual awareness was suppressed by applying TMS to the occipital pole. The nature of subjects’ performance whilst undergoing occipital TMS was then verified by use of a psychophysical measure (d'') that is independent of response criteria. This showed that there was no genuine dissociation in visual sensitivity measured by yes-no and forced-choice responses. These results highlight that evidence for visual sensitivity in the absence of awareness must be analysed using a bias-free psychophysical measure, such as d'', In order to confirm whether or not visual performance is truly unconscious.     

The flexible nature of unconscious cognition

The cognitive signature of unconscious processes is hotly debated recently. Generally, consciousness is thought to mediate flexible, adaptive and goal-directed behavior, but in the last decade unconscious processing has rapidly gained ground on traditional conscious territory. In this study we demonstrate that the scope and impact of unconscious information on behavior and brain activity can be modulated dynamically on a trial-by-trial basis. Participants performed a Go/No-Go experiment in which an unconscious (masked) stimulus preceding a conscious target could be associated with either a Go or No-Go response. Importantly, the mapping of stimuli onto these actions varied on a trial-by-trial basis, preventing the formation of stable associations and hence the possibility that unconscious stimuli automatically activate these control actions. By eliminating stimulus-response associations established through practice we demonstrate that unconscious information can be processed in a flexible and adaptive manner. In this experiment we show that the same unconscious stimulus can have a substantially different effect on behavior and (prefrontal) brain activity depending on the rapidly changing task context in which it is presented. This work suggests that unconscious information processing shares many sophisticated characteristics (including flexibility and context-specificity) with its conscious counterpart.     

The effect of stimulus duration and motor response in hemispatial neglect during a visual search task

Patients with hemispatial neglect exhibit a myriad of profound deficits. A hallmark of this syndrome is the patients' absence of awareness of items located in their contralesional space. Many studies, however, have demonstrated that neglect patients exhibit some level of processing of these neglected items. It has been suggested that unconscious processing of neglected information may manifest as a fast denial. This theory of fast denial proposes that neglected stimuli are detected in the same way as non-neglected stimuli, but without overt awareness. We evaluated the fast denial theory by conducting two separate visual search task experiments, each differing by the duration of stimulus presentation. Specifically, in Experiment 1 each stimulus remained in the participants' visual field until a response was made. In Experiment 2 each stimulus was presented for only a brief duration. We further evaluated the fast denial theory by comparing verbal to motor task responses in each experiment. Overall, our results from both experiments and tasks showed no evidence for the presence of implicit knowledge of neglected stimuli. Instead, patients with neglect responded the same when they neglected stimuli as when they correctly reported stimulus absence. These findings thus cast doubt on the concept of the fast denial theory and its consequent implications for non-conscious processing. Importantly, our study demonstrated that the only behavior affected was during conscious detection of ipsilesional stimuli. Specifically, patients were slower to detect stimuli in Experiment 1 compared to Experiment 2, suggesting a duration effect occurred during conscious processing of information. Additionally, reaction time and accuracy were similar when reporting verbally versus motorically. These results provide new insights into the perceptual deficits associated with neglect and further support other work that falsifies the fast denial account of non-conscious processing in hemispatial visual neglect.     

Time Slices: What Is the Duration of a Percept?

We experience the world as a seamless stream of percepts. However, intriguing illusions and recent experiments suggest that the world is not continuously translated into conscious perception. Instead, perception seems to operate in a discrete manner, just like movies appear continuous although they consist of discrete images. To explain how the temporal resolution of human vision can be fast compared to sluggish conscious perception, we propose a novel conceptual framework in which features of objects, such as their color, are quasi-continuously and unconsciously analyzed with high temporal resolution. Like other features, temporal features, such as duration, are coded as quantitative labels. When unconscious processing is “completed,” all features are simultaneously rendered conscious at discrete moments in time, sometimes even hundreds of milliseconds after stimuli were presented.     

Brain activity in an awake chimpanzee in response to the sound of her own name

The brain activity of a fully awake chimpanzee being presented with her name was investigated. Event-related potentials (ERPs) were measured for each of the following auditory stimuli: the vocal sound of the subject''s own name (SON), the vocal sound of a familiar name of another group member, the vocal sound of an unfamiliar name and a non-vocal sound. Some differences in ERP waveforms were detected between kinds of stimuli at latencies at which P3 and Nc components are typically observed in humans. Following stimulus onset, an Nc-like negative shift at approximately 500 ms latency was observed, particularly in response to SON. Such specific ERP patterns suggest that the chimpanzee processes her name differently from other sounds.     

Effects of subthalamic nucleus stimulation on emotional prosody comprehension in Parkinson's disease

Background

Although impaired decoding of emotional prosody has frequently been associated with Parkinson''s disease (PD), to date only few reports have sought to explore the effect of Parkinson''s treatment on disturbances of prosody decoding. In particular, little is known about how surgical treatment approaches such as high frequency deep brain stimulation (DBS) affect emotional speech perception in patients with PD. Accordingly, the objective of this study was to evaluate the effect of subthalamic nucleus (STN) stimulation on prosody processing.

Methodology/Principal Findings

To this end the performance of 13 PD patients on three tasks requiring the decoding of emotional speech was assessed and subsequently compared to the performance of healthy control individuals. To delineate the effect of STN-DBS, all patients were tested with stimulators turned on as well as with stimulators turned off. Results revealed that irrespective of whether assessments were made “on” or “off” stimulation, patients'' performance was less accurate as compared to healthy control participants on all tasks employed in this study. However, while accuracy appeared to be unaffected by stimulator status, a facilitation of reactions specific to highly conflicting emotional stimulus material (i.e. stimulus material presenting contradicting emotional messages on a verbal and non-verbal prosodic level) was observed during “on” stimulation assessments.

Conclusion

In sum, presented results suggest that the processing of emotional speech is indeed modulated by STN-DBS. Observed alterations might, on the one hand, reflect a more efficient processing of highly conflicting stimulus material following DBS. However, on the other hand, given the lack of an improvement in accuracy, increased impulsivity associated with STN stimulation needs to be taken into consideration.     

Mirror adaptation in sensory-motor simultaneity

Background

When one watches a sports game, one may feel her/his own muscles moving in synchrony with the player''s. Such parallels between observed actions of others and one''s own has been well supported in the latest progress in neuroscience, and coined “mirror system.” It is likely that due to such phenomena, we are able to learn motor skills just by observing an expert''s performance. Yet it is unknown whether such indirect learning occurs only at higher cognitive levels, or also at basic sensorimotor levels where sensorimotor delay is compensated and the timing of sensory feedback is constantly calibrated.

Methodology/Principal Findings

Here, we show that the subject''s passive observation of an actor manipulating a computer mouse with delayed auditory feedback led to shifts in subjective simultaneity of self mouse manipulation and auditory stimulus in the observing subjects. Likewise, self adaptation to the delayed feedback modulated the simultaneity judgment of the other subjects manipulating a mouse and an auditory stimulus. Meanwhile, subjective simultaneity of a simple visual disc and the auditory stimulus (flash test) was not affected by observation of an actor nor self-adaptation.

Conclusions/Significance

The lack of shift in the flash test for both conditions indicates that the recalibration transfer is specific to the action domain, and is not due to a general sensory adaptation. This points to the involvement of a system for the temporal monitoring of actions, one that processes both one''s own actions and those of others.     

Neural Correlates of Own Name and Own Face Detection in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition clinically characterized by social interaction and communication difficulties. To date, the majority of research efforts have focused on brain mechanisms underlying the deficits in interpersonal social cognition associated with ASD. Recent empirical and theoretical work has begun to reveal evidence for a reduced or even absent self-preference effect in patients with ASD. One may hypothesize that this is related to the impaired attentional processing of self-referential stimuli. The aim of our study was to test this hypothesis. We investigated the neural correlates of face and name detection in ASD. Four categories of face/name stimuli were used: own, close-other, famous, and unknown. Event-related potentials were recorded from 62 electrodes in 23 subjects with ASD and 23 matched control subjects. P100, N170, and P300 components were analyzed. The control group clearly showed a significant self-preference effect: higher P300 amplitude to the presentation of own face and own name than to the close-other, famous, and unknown categories, indicating preferential attentional engagement in processing of self-related information. In contrast, detection of both own and close-other''s face and name in the ASD group was associated with enhanced P300, suggesting similar attention allocation for self and close-other related information. These findings suggest that attention allocation in the ASD group is modulated by the personal significance factor, and that the self-preference effect is absent if self is compared to close-other. These effects are similar for physical and non-physical aspects of the autistic self. In addition, lateralization of face and name processing is attenuated in ASD, suggesting atypical brain organization.     

Will we wake up to biodiversity?: The International Year of Biodiversity has failed to raise awareness or halt decline as economic crises and political interests have sidelined the environment

Looking back on the International Year of Biodiversity, some conservationists hope that it has raised awareness, if nothing else. Even so, many scientists remain pessimistic about our efforts to halt biodiversity decline.The United Nations'' (UN) International Year of Biodiversity in 2010 was supposed to see the adoption of measures that would slow global environmental decline and the continuing loss of endangered species and habitats. Even before, in 2002, most UN members had committed to halting the decline in biodiversity, which is a measure of the health of ecosystems. But the results of these international efforts have been funereal. Moreover, the current global economic crisis, coupled with growing anti-science attitudes in the USA, are adding to the concern of scientists about whether there is the political will to address the loss of biodiversity and whether habitat loss and extinction rates are reaching a point of no return.“There is not a single report received last year that claimed to have stopped or reduced the loss of biodiversity”Ahmed Djoghlaf, Executive Secretary of the Convention on Biological Diversity under the UN Environment Programme based in Montreal, Canada, said that of the 175 national reports submitted as part of the International Year of Biodiversity to his agency last year, none reported any progress. “There is not a single report received last year that claimed to have stopped or reduced the loss of biodiversity,” he said. “These reports confirm that the rate of loss of biodiversity today is unprecedented and the rate is 1,000 higher than the rate of natural extinction on species, and [his agency''s Global Biodiversity Outlook 2010; UN, 2010a] predicts that if business is allowed to continue then major ecosystems, the ocean, the fish, the forests, will reach the tipping point, meaning that there will be irreversible and irreparable damage done to the ecosystems.”The UN campaign traces its roots to the European Union (EU) commitment in 2001 to halt the loss of biodiversity by 2010. The 2010 goal was incorporated into the UN Millennium Development Goals because of the severe impact of biodiversity loss on human well-being. However, the EU last year conceded in a report that it missed its 2010 target, too. The EU''s Biodiversity Action Plan, launched in 2006, shows that Europe''s biodiversity “remains under severe threat from the excessive demands we are making on our environment, such as changes in land use, pollution, invasive species and climate change.” Yet, EU Environment Commissioner Janez Potočnik has seen some positive signs: “We have learned some very important lessons and managed to raise biodiversity to the top of the political agenda. But we need everyone on board and not just in Europe. The threat around the world is even greater than in the EU,” he wrote last year (EC, 2010).Despite the initiative''s poor report card, Djoghlaf was upbeat about the International Year of Biodiversity. “It was a success because it was celebrated everywhere,” he said. “In Switzerland, they conducted a survey before and after the International Year of Biodiversity and they concluded that at the end of the year, 67% of all the Swiss people are now aware of biodiversity. When the year started it was 40%. People are more and more aware. In addition, biodiversity has entered the top of the political agenda.”In October 2010, delegates from 193 countries attended the UN Convention on Biodiversity in Nagoya, Japan, and adopted 20 strategic goals to be achieved by 2020 (UN, 2010b). The so-called Aichi Biodiversity Targets include increased public awareness of the values of biodiversity and the steps that individuals can take to conserve and act sustainably; the halving or halting of the rate of loss of all natural habitats, including forests; and the conservation of 17% of terrestrial and inland water, and 10% of coastal and marine areas through effective and equitable management, resulting in ecologically representative and well-connected systems. By contrast, 13% of land areas and 1% of marine areas were protected in 2010.However, the Convention on Biological Diversity is not enforceable. Anne Larigauderie, Executive Director of DIVERSITAS (Paris, France), which promotes research on biodiversity science, said that it is up to the individual countries to adopt enforceable legislation. “In principle, countries have committed. Now it depends on what individual countries are going to do with the agreement,” she said. “I would say that things are generally going in the right direction and it''s too early to tell whether or not it''s going to have an impact in terms of responding and in terms of the biodiversity itself.”Researchers, however, have been disappointed by The International Year of Biodiversity. Conservation biologist Stuart Butchart, of Birdlife International in Cambridge, UK—a partnership of non-governmental environmental organizations and colleagues from other environmental groups—compiled a list of 31 indicators to measure progress towards the 2010 goal of the International Year of Biodiversity. He and his collaborators reported in Science (Butchart et al, 2010) that these indicators, including species population trends, extinction risks and habitat conditions, showed declines with no significant rate reductions. At the same time, indicators of pressure on biodiversity, such as resource consumption, invasive alien species, nitrogen pollution, over-exploitation and climate change impacts showed increases. “Despite some local successes and increasing responses (including extent and biodiversity coverage of protected areas, sustainable forest management, policy responses to invasive alien species and biodiversity-related aid), the rate of biodiversity loss does not appear to be slowing,” the researchers wrote.​wrote.Open in a separate window© Thomas Kitchin & Victoria Hurst/Wave/CorbisButchart pointed out that even if the International Year of Biodiversity had an impact on raising awareness and reducing biodiversity loss, detecting the change would take time. He said that the International Year of Biodiversity fell short of increasing awareness in parts of government not dealing with the environment, including ministries of transport, tourism, treasury and finance. It also seems probable that the campaign had little impact on the business sector, which affects development projects with a direct impact on biodiversity. “People can''t even seem to get together on global climate change, which is a whole lot more obvious and right there,” Peter Raven, president emeritus of the Missouri Botanical Gardens in St Louis, USA, explained. “Biodiversity always seems to be a sort of mysterious background thing that isn''t quite there.”“People can''t even seem to get together on global climate change, which is a whole lot more obvious and right there…”Illka Hanski, a professor in the Department of Ecology and Evolutionary Biology at the University of Helsinki in Finland, said that studies such as Butchart''s “indicate that nothing really happened in 2010. Biodiversity decline continued and has been declining over the past 10 years.”Other researchers are more positive, although with reservations. Conservation biologist Thomas Eugene Lovejoy III, Heinz Center Biodiversity Chair and former president of the Center in Washington, DC, USA—a non-partisan, non-profit organization dedicated to advancing sound environmental policy—said that economic trends affect biodiversity and that biodiversity efforts might actually be benefiting from the current global economic crisis. For example, the decline in the housing markets in the USA and Europe has reduced the demand on lumber for new construction and has led to a reduction in deforestation. “Generally speaking, when there is an economic downturn, some of the things that are pressuring biodiversity actually abate somewhat. That''s the good news. The bad news is that the ability to marshal resources to do some things proactively gets harder,” he said.Chris Thomas, a conservation biologist at the University of York in the UK, who studies ecosystems and species in the context of climate change, said that economic depressions do slow the rate of damage to the environment. “But it also takes eyes off the ball of environmental issues. It''s not clear whether these downturns, when you look over a period of a decade, make much difference or not.” Hanski agreed: “[B]ecause there is less economic activity, there may be less use of resources and such. But I don''t think this is a way to solve our problems. It won''t lead to any stable situation. It just leads to a situation where economic policies become more and more dependent on measures that try actually just to increase the growth as soon as possible.”…biodiversity efforts might actually be benefiting from the current global economic crisisRaven said that in bad times, major interests such as those involved in raising cattle, growing soybeans and clearing habitat for oil palms have reduced political clout because there is less money available for investment. But he said economic downturns do not slow poor people scrounging for sustenance in natural habitats.To overcome this attitude of neglect, Lovejoy thinks there ought to be a new type of ‘economics'' that demonstrates the benefits of biodiversity and brings the “natural world into the normal calculus.” Researchers are already making progress in this direction. Thomas said that the valuation of nature is one of the most active areas of research. “People have very different opinions as to how much of it can be truly valued. But it is a rapidly developing field,” he said. “Once you''ve decided how much something is worth, then you''ve got to ask what are the financial or other mechanisms by which the true value of this resource can be appreciated.”Hanski said that the main problem is the short-term view of economic forecasts. “Rapid use of natural resources because of short-term calculation may actually lead to a sort of exploitation rather than conservation or preservation.” He added that the emphasis on economic growth in rich societies in North America and Europe is frustrating. “We have become much richer than in 1970 when there actually was talk of zero growth in serious terms. So now we are richer and we are becoming more and more dependent on continued growth, the opposite of what we should be aiming at. It''s a problem with our society and economics clearly, but I can''t be very optimistic about the biodiversity or other environmental issues in this kind of situation.” He added that biodiversity is still taking a backseat to economics: “There is a very long way to go right now with the economic situation in Europe, it''s clear that these sorts of [biodiversity] issues are not the ones which are currently being debated by the heads of states.”The economic downturn, which has led to reduced government and private funding and declines in endowments, has also hurt organizations dedicated to preserving biodiversity. Butchart said that some of the main US conservation organizations, including the Nature Conservancy and the World Wildlife Federation, have experienced staff cuts up to 30%. “Organizations have had to tighten their belts and reign in programmes just to stay afloat, so it''s definitely impacted the degree to which we could work effectively,” he said. “Most of the big international conservation organizations have had to lay off large numbers of staff.”…a new type of ‘economics'' that demonstrates the benefits of biodiversity and brings the “natural world into the normal calculus”Cary Fowler, Executive Director of the Global Crop Diversity Trust in Rome, Italy, a public–private partnership to fund key crop collections for food security, also feels the extra challenges of the global economic crisis. “We invest our money conservatively like a foundation would in order to generate income that can reliably pay the bills in these seed banks year after year. So I''m always nervous and I have the computer on at the moment looking at what''s happening with the sovereign debt crisis here in Europe. It''s not good,” he said. “Governments are not being very generous with contributions to this area. Donors will rarely give a reason [for cutting funding].”The political situation in the USA, the world''s largest economy, is also not boding well for conservation of and research into biodiversity. The political extremism of the Republican Party during the run up to the 2012 presidential election has worried many involved in biodiversity issues. Republican contender Texas Governor Rick Perry has been described as ‘anti-science'' for his denial of man-made climate change, a switch from the position of 2008 Republican candidate John McCain. Perry was also reported to describe evolution as a “theory that''s out there, and it''s got some gaps in it” at a campaign event in New Hampshire earlier in the year.“Most of the big international conservation organizations have had to lay off large numbers of staff”Raven said this attitude is putting the USA at a disadvantage. “It drives us to an anti-intellectualism and a lack of real verification for anything which is really serious in terms of our general level of scientific education and our ability to act intelligently,” he said.Still, Larigauderie said that although the USA has not signed the conventions on biodiversity, she has seen US observers attend the meetings, especially under the Obama administration. “They just can''t speak,” she said. Meanwhile, Lovejoy said that biodiversity could get lost in the “unbelievable polarisation affecting US politics. I have worked out of Washington for 36 years now—I''ve never seen anything like this: an unwillingness to actually listen to the other side.”Raven said it is vital for the USA to commit to preserving biodiversity nationally and internationally. “It''s extremely important because our progress towards sustainability for the future will depend on our ability to handle biodiversity in large part. We''re already using about half of all the total photosynthetic productivity on land worldwide and that in turn means we''re cutting our options back badly. The US is syphoning money by selling debt and of course promoting instability all over the world,” he explained. “It''s clear that there is no solution to it other than a level population, more moderate consumption levels and new technologies altogether.”The EU and the UN have also changed the time horizon for halting the decline in biodiversity. As part of the Nagoya meeting, the UN announced the UN Decade for Biodiversity. The strategic objectives include a supporting framework for the implementation of the Biodiversity Strategic Plan 2011–2020 and the Aichi Biodiversity Targets, as well as guidance to regional and international organizations, and more public awareness of biodiversity issues.But Butchart remains sceptical. “I suspect ‘decades of whatever'' have even less impact than years,” he said. “2008 was the International Year of the Potato. I don''t know how much impact that had on your life and awareness. I think there is greater awareness and greater potential to make significant progress in addressing biodiversity loss now than there was 10 years ago, but the scale of the challenge is still immense.”“…our progress towards sustainability for the future will depend on our ability to handle biodiversity in large part”Hanski has similar doubts. “I believe it''s inevitable that a very large fraction of the species on Earth will go extinct in the next hundred years. I can''t see any change to that.” But he is optimistic that some positive change can be made. “Being pessimistic doesn''t help. The nations still can make a difference.” He said he has observed ecotourism playing a role in saving some species in Madagascar, where he does some of his research.“We''re not going to fundamentally be able to wipe life off the planet,” Thomas said. “We will wipe ourselves off the planet virtually certainly before we wipe life out on Earth. However, from the point of view of humanity as a culture, and in terms of the resources we might be able to get from biodiversity indirectly or directly, if we start losing things then it takes things millions of years to ‘re-evolve'' something that does an equivalent job. From a human perspective, when we wipe lots of things out, they''re effectively permanently lost. Of course it would be fascinating and I would love to be able to come back to the planet in 10 million years and see what it looks like, assuming humans are not here and other stuff will be.”Djoghlaf, by contrast, is more optimistic about our chances: “I believe in the human survival aspect. When humankind realises that the current pattern of production and consumption and the current way that it is dealing with nature is unsustainable, we will wake up.”     

Momentary Conscious Pairing Eliminates Unconscious-Stimulus Influences on Task Selection

Task selection, previously thought to operate only under conscious, voluntary control, can be activated by unconsciously-perceived stimuli. In most cases, such activation is observed for unconscious stimuli that closely resemble other conscious, task-relevant stimuli and hence may simply reflect perceptual activation of consciously established stimulus-task associations. However, other studies have reported ‘direct’ unconscious-stimulus influences on task selection in the absence of any conscious, voluntary association between that stimulus and task (e.g., Zhou and Davis, 2012). In new experiments, described here, these latter influences on cued- and free-choice task selection appear robust and long-lived, yet, paradoxically, are suppressed to undetectable levels following momentary conscious prime-task pairing. Assessing, and rejecting, three intuitive explanations for such suppressive effects, we conclude that conscious prime-task pairing minimizes non-strategic influences of unconscious stimuli on task selection, insulating endogenous choice mechanisms from maladaptive external control.     

I research,therefore I am?: A purely scientific understanding of consciousness remains elusive,but the search for its neurological foundation continues

The exploration of consciousness—the most elusive characteristic of human nature—has long been left to philosophers and artists. Using modern research tools, scientists have finally begun to subject the human mind to empirical analysis.Consciousness is the heart of human existence, yet it has proven to be an elusive subject for scientific research and analysis. Its study has largely been left to philosophers, writers and artists who have spent centuries exploring the meaning of life. Existential questions such as ‘why am I me?'' are, by their nature, difficult to answer with empirical analysis. It is therefore perhaps unsurprising that natural science has found it difficult to add detail to René Descartes general principle: cognito ergo sum. From some quarters—particularly religious ones—there has also been resistance to the ‘profane'' tools of science probing the ‘sacred heart'' of human consciousness; Pope John Paul II is reported to have proclaimed during a conference at the Vatican in the 1980s, that while scientists can have the brain, the mind belongs to God (Lane, 2009).Existential questions such as ‘why am I me?'' are, by their nature, difficult to answer with empirical analysisThe separation of mind and brain is fundamental to the study of consciousness, and requires elucidation of the relationship between the biological mechanisms of brain function and the higher-level processes—such as emotion or reason—that are enabled by them. Although the ultimate meaning of human existence remains elusive—assuming that there is one—research has begun to unravel the physical mechanisms that enable consciousness, by using brain imaging techniques together with an increasing understanding of the neuronal architecture of the brain. This approach has informed the quest to identify the neural correlates of consciousness (Crick & Koch, 1990) that were first defined by Christof Koch, Professor of Biology and Engineering at the California Institute of Technology, and Francis Crick, who is better known for his codiscovery of the DNA double helix. These correlates are defined as the minimal set of neuronal mechanisms required for a particular conscious function or ability. Their identification would be useful for assessing levels of consciousness in animals, infants and adults with brain damage or disease, who are unable to express what they are feeling in words.Koch explained that although neuronal mechanisms are necessary for consciousness, it is the information that they transmit and integrate that actually brings it into being; an idea that was first advanced by Giulio Tononi (2004), to which Koch has contributed. This theory, according to Koch, states that consciousness depends on the ability to coherently integrate information, irrespective of the information type. This has important implications: that consciousness is independent of language, vision or any other specific form of information, and can exist in any system with the required structure. From this, Koch has concluded that consciousness is not limited to humans, but could exist in a machine and many animals—a view that has led him to become a vegetarian. According to this theory, aspects of recent human evolution and culture—including language—are products of consciousness, rather than requirements for it.According to Naomi Eilan, Director of the Consciousness and Self-Consciousness Research Centre at the University of Warwick, UK, the information flows and synchronization that enable consciousness are nevertheless dependent on the physical structure of the brain. “It''s mad to think that consciousness and the brain are independent [of one another],” she said. The extent of their interdependence, however, is hotly debated. According to Eilan, scientists generally take one of three positions on the subject: “[O]ne view [is that] the brain will tell us what consciousness is, but at the other [extreme] there''s the view that it''s neither here nor there and that the brain is one thing and consciousness quite another. I''m in the middle, where the brain presupposes consciousness but does not explain it. The brain will not tell you what consciousness is, but it does tell us how various aspects of it work.”…consciousness is independent of language, vision or any other specific form of information, and can exist in any system with the required structureIn evolutionary terms, consciousness is a phenotype with an underlying genotype. It is therefore subject to the pressures of natural selection, which act at the level of the genes encoding neurological structures. These structures probably first emerged in animals for specific functions and only later became integrated into a universal continuous consciousness, according to Antonio Damasio, Director of the Brain and Creativity Institute at the University of Southern California, Los Angeles, USA. “I believe most of the phenomena of consciousness emerged as a result of specific brain complexities which were required by an improved life regulation,” he said. “But once basic consciousness emerged, its adaptive value was so remarkable that natural selection made it prevail.”​Open in a separate window© MedicalRF.com/CorbisIt is now almost universally agreed that consciousness is linked to the coherence of the electrical states of different groups of neurons, but the mechanisms underlying this are still disputed. Some researchers, such as the American psychologist Stuart Hameroff, argue that quantum mechanics must be involved through a phenomenon known as quantum coherence, which would correlate the states of subatomic particles across the brain (Hameroff, 1994). This hypothesis is questioned by others, but consciousness does seem to be generated by synchronized oscillations in the electrical states of neurons in different areas of the brain, as detected by electroencephalography.…aspects of recent human evolution and culture—including language—are products of consciousness, rather than requirements for itFor electrical coherence to occur, structures that can synchronize disparate brain regions must have evolved at some stage. Prime candidates are the calcium-binding (calbindin) positive cells in the thalamus—a structure that relays signals relating to spatial and motor awareness between the cerebral cortex and midbrain, as well as regulating sleep and alertness. Calbindin proteins modulate the flow of calcium within neurons, affecting synaptic activity and neuronal activation. The calbindin positive cells in the thalamus can thereby facilitate high-frequency oscillations in different regions of the cortex (Joliot et al, 1994). According to Koch, such cells might be crucial messengers for consciousness, enabling effective interactions between different cortical regions. In support of this, when calbindin positive thalamic cells lose their ability to activate other neurons—as a result of injury or disease—these patients are in a vegetative state even when their cortical tissue is intact.The above observation is an example of how the study of brain-damaged patients can shed light on the underlying mechanisms of consciousness. It also led to the development of a possible treatment for such patients. Niko Schiff and colleagues found that deep-brain electrical stimulation of the central thalamus restored some behavioural responsiveness in a patient who had been minimally conscious for 6 years (Schiff et al, 2007).In evolutionary terms, consciousness is a phenotype with an underlying genotypeSudden recovery from prolonged states of minimal consciousness can also indicate which structures of the brain are required for normal states of awareness and activity. A study by Henning Voss and colleagues in New York and New Zealand found evidence that axonal regrowth led to the dramatic recovery of speech in a patient who had been in a minimally conscious state for 19 years after a road accident in 1984 (Voss et al, 2006). Axonal regrowth was shown by use of a new imaging technique, Diffusion Tensor Imaging (DTI), as the patient quickly regained the ability to talk with increasing fluency over a period of a few days. DTI is a form of magnetic resonance imaging (MRI) that forms images by observing the Brownian motion of water molecules. It showed axons sprouting from neurons in the intact part of the cortex. Further evidence came from positron emission tomography scans of the same brain areas, showing increased glucose metabolism that seemed to be linked with the neuronal regrowth, which would explain the patient''s recovery.Sudden recovery from prolonged states of minimal consciousness can also indicate which structures of the brain are required for normal states of awareness and activityKoch noted that this and other neuroimaging studies of vegetative state or minimally conscious patients have found that even a prolonged loss of consciousness can be reversed. Another important question is whether consciousness can be detected when patients are in a persistent vegetative state and cannot communicate verbally or by movement. Observing responses to stimuli in specific brain areas is not sufficient to assess the level of consciousness, as these reactions can occur without consciousness, as they do during sleep.To address this question, Adrian Owen and colleagues in the UK and Belgium conducted an ingenious experiment with a female patient who was incapable of responding to external stimuli. The researchers asked the patient to imagine playing tennis while they observed her in an MRI scanner. They found that the same cortical areas were activated as when normal individuals perform the same task (Owen et al, 2006). Koch points out that the task could not have been performed by unconscious processing of external stimuli, as the patient was only imagining the action.This result does not conclusively show that the patient was conscious, as the neural correlates of thought processes remain unclear. However, the above observation suggests that the patient might be more than minimally conscious, as she had been diagnosed. Owen''s colleague, Steven Laureys, has since been involved in several studies indicating that almost half of people with disorders of consciousness are wrongly diagnosed as being in a vegetative state. According to Laureys, these findings might indicate that some patients have had their life support turned off as a result of such misdiagnoses, even though they could have subsequently regained consciousness, to some extent.At present, this suggestion is controversial and does no more than provide a source of acute uncertainty for the families and doctors of such patients. In future, however, brain imaging could help clinicians to make more accurate diagnoses. In one of the most striking examples so far, Christine Ecker and colleagues at King''s College and University College, London, UK, have identified characteristic structural features of the brain that can be used to reliably diagnose autism spectrum disorder (ASD; Ecker et al, 2010). They used MRI to measure certain brain features in patients with ASD—such as the thickness and degree of folding in particular areas of the cortex—and combined this information to obtain a correlate picture of the brain changes that are unique to ASD. This was an important development, as ASD is complex and associated with many cortical features that have previously been difficult to categorize. By using this new approach, ASD can now be clearly distinguished from other conditions and accurate, rapid diagnosis in early life could make a notable difference for sufferers.“the study of consciousness is now moving from the domain of philosophy and metaphysics into the empirical domain of science”This work might also guide research on the genetic and neurological bases of ASD, by identifying the anatomical features and ultimately individual proteins that are implicated in the disorder. Some of the cortical regions involved seem to be unique, which resonates with more general research into various aspects of consciousness.This type of applied research into consciousness is at the opposite end of the spectrum to the ongoing attempts to unite the scientific and philosophical approaches to studying the subject. Indeed, as Koch noted, “the study of consciousness is now moving from the domain of philosophy and metaphysics into the empirical domain of science.”This move is creating the ultimate challenge for multidisciplinary research; it requires the interaction of two fields with little history or experience of collaboration. According to Bill Brewer, who specializes in the philosophy of perception at Warwick University, UK, “this is a massive philosophical question in itself: what is the relationship between philosophical and scientific approaches to mental phenomena in general and conscious experience in particular?” Brewer believes that such efforts will ultimately prove successful; “My own opinion, having been part of a number of interdisciplinary projects concerned with such matters, is that there is no general abstract recipe for fruitful collaboration. It requires long periods of open-minded mutual learning, teaching and open-ended discussion of very specific questions and issues in the various different fields until it eventually becomes clear that a good deal in the disciplinary boundaries is arbitrary and all parties are actually concerned with the same fundamental problems in ways that merge into a continuum of approaches.”Whether this will lead to a full understanding of consciousness and whether science has something to say about the ‘meaning'' of our existence remains to be seen.     

On the time course of vocal emotion recognition

How quickly do listeners recognize emotions from a speaker''s voice, and does the time course for recognition vary by emotion type? To address these questions, we adapted the auditory gating paradigm to estimate how much vocal information is needed for listeners to categorize five basic emotions (anger, disgust, fear, sadness, happiness) and neutral utterances produced by male and female speakers of English. Semantically-anomalous pseudo-utterances (e.g., The rivix jolled the silling) conveying each emotion were divided into seven gate intervals according to the number of syllables that listeners heard from sentence onset. Participants (n = 48) judged the emotional meaning of stimuli presented at each gate duration interval, in a successive, blocked presentation format. Analyses looked at how recognition of each emotion evolves as an utterance unfolds and estimated the “identification point” for each emotion. Results showed that anger, sadness, fear, and neutral expressions are recognized more accurately at short gate intervals than happiness, and particularly disgust; however, as speech unfolds, recognition of happiness improves significantly towards the end of the utterance (and fear is recognized more accurately than other emotions). When the gate associated with the emotion identification point of each stimulus was calculated, data indicated that fear (M = 517 ms), sadness (M = 576 ms), and neutral (M = 510 ms) expressions were identified from shorter acoustic events than the other emotions. These data reveal differences in the underlying time course for conscious recognition of basic emotions from vocal expressions, which should be accounted for in studies of emotional speech processing.     

Attentional load modulates responses of human primary visual cortex to invisible stimuli

Visual neuroscience has long sought to determine the extent to which stimulus-evoked activity in visual cortex depends on attention and awareness. Some influential theories of consciousness maintain that the allocation of attention is restricted to conscious representations [1, 2]. However, in the load theory of attention [3], competition between task-relevant and task-irrelevant stimuli for limited-capacity attention does not depend on conscious perception of the irrelevant stimuli. The critical test is whether the level of attentional load in a relevant task would determine unconscious neural processing of invisible stimuli. Human participants were scanned with high-field fMRI while they performed a foveal task of low or high attentional load. Irrelevant, invisible monocular stimuli were simultaneously presented peripherally and were continuously suppressed by a flashing mask in the other eye [4]. Attentional load in the foveal task strongly modulated retinotopic activity evoked in primary visual cortex (V1) by the invisible stimuli. Contrary to traditional views [1, 2, 5, 6], we found that availability of attentional capacity determines neural representations related to unconscious processing of continuously suppressed stimuli in human primary visual cortex. Spillover of attention to cortical representations of invisible stimuli (under low load) cannot be a sufficient condition for their awareness.     

Coding "what" and "when" in the Archer fish retina

Traditionally, the information content of the neural response is quantified using statistics of the responses relative to stimulus onset time with the assumption that the brain uses onset time to infer stimulus identity. However, stimulus onset time must also be estimated by the brain, making the utility of such an approach questionable. How can stimulus onset be estimated from the neural responses with sufficient accuracy to ensure reliable stimulus identification? We address this question using the framework of colour coding by the archer fish retinal ganglion cell. We found that stimulus identity, “what”, can be estimated from the responses of best single cells with an accuracy comparable to that of the animal''s psychophysical estimation. However, to extract this information, an accurate estimation of stimulus onset is essential. We show that stimulus onset time, “when”, can be estimated using a linear-nonlinear readout mechanism that requires the response of a population of 100 cells. Thus, stimulus onset time can be estimated using a relatively simple readout. However, large nerve cell populations are required to achieve sufficient accuracy.

Authors Summary

In our interaction with the environment we are flooded with a stream of numerous objects and events. Our brain needs to understand the nature of these complex and rich stimuli in order to react. Research has shown ways in which a ‘what’ stimulus was presented can be encoded by the neural responses. However, to understand ‘what was the nature of the stimulus’ the brain needs to know ‘when’ the stimulus was presented. Here, we investigated how the onset of visual stimulus can be signalled by the retina to higher brain regions. We used archer fish as a framework to test the notion that the answer to the question of ‘when’ something has been presented lies within the larger cell population, whereas the answer to the question of ‘what’ has been presented may be found at the single-neuron level. The utility of the archer fish as model animal stems from its remarkable ability to shoot down insects settling on the foliage above the water level, and its ability to distinguish between artificial targets. Thus, the archer fish can provide the fish equivalent of a monkey or a human that can report psychophysical decisions.     

Testing time for telomeres

Our knowledge of the importance of telomeres to health and ageing continues to grow. Some scientists are therefore commercializing their research, whereas others believe we need an even deeper understanding before we can interpret the results.After 30 years of research, the analysis of telomere length is emerging as a commercial biomarker for ageing and disease, as well as a tool in the search for new medications. Several companies offer tests for telomere length, and more are due to launch their products shortly. Even so, and despite the commercial enthusiasm, interpreting precisely what an individual''s telomeres mean for their health and longevity remains challenging. As a result, there is some division within the research community between those who are pushing ahead with ventures to offer tests to the public, and those who feel that telomere testing is not yet ready for prime time.Peter Lansdorp, a scientist at the British Columbia Cancer Agency and a professor at the University of British Columbia (Vancouver, Canada), founded his company, Repeat Diagnostics, in response to the number of questions and requests he received from physicians for tests for telomere length. The company became the first to offer commercial telomere testing in 2005 and now mainly serves medical researchers, although it makes its test available to the public through their physicians for C $400. Nevertheless, Lansdorp thinks that testing is of limited use for the public. “Testing [...] outside the context of research studies is in my view premature. Unfortunately I think some scientists are exploiting it,” he said. “At this point, I would discourage people from getting their telomeres tested unless there are symptoms in the family that may point to a telomere problem, or a disease related to a telomere problem. I don''t see why on Earth you would want to do that for normal individuals.”“Testing [...] outside the context of research studies is in my view premature. Unfortunately I think some scientists are exploiting it”Others are more convinced of the general utility of telomere tests, when used in combination with other diagnostic tools. Elizabeth Blackburn, Professor of Biology and Physiology at the University of California (San Francisco, USA), was a co-recipient of the Nobel Prize for Physiology or Medicine in 2009 for her part in the discovery of telomerase, the enzyme that replenishes telomeres (Sidebar A). She stressed that the point of telomere testing is to obtain an overall picture “using a marker that integrates many inputs, and produces a robust statistical association with [...] disease risks. It is not a specific diagnostic.” Telome Health, Inc. (Menlo Park, California, USA)—the company that Blackburn helped found and that she now advises in a scientific capacity—plans to begin selling its own US $200 telomere test later this year. “The science has been emerging at a rapid pace recently [...] for those who are familiar with the wealth of the evidence and the accumulated data, the overwhelming pattern is that there are clear associations with telomere maintenance, including longitudinal patterns, and health measures that have had well-tested clinical relevance,” she explained.

Sidebar A | Telomeres and telomerase

Telomeres are regions of repetitive DNA sequence that prevent the DNA replication process or damage from degrading the ends of chromosomes, essentially acting as buffers and protecting the genes closest to the chromosome ends. Russian biologist Alexei Olovnikov first hypothesized in the early 1970s that chromosomes could not completely replicate their ends, and that such losses could ultimately lead to the end of cell division (Olovnikov, 1973). Some years later, Elizabeth Blackburn, then a postdoctoral fellow in Joseph Gall''s lab at Yale University (New Haven, Connecticut, USA), and her colleagues published work suggesting that telomere shortening was linked with ageing at the cellular level, affected lifespan and could lead to cancer (Blackburn & Gall, 1978; Szostak & Blackburn, 1982). In 1984, Carol Greider, working as a postdoc in Blackburn''s lab at the University of California (Berkeley, USA), discovered telomerase, the enzyme that replenishes telomeres. Blackburn and Greider, together with Jack Szostak, were awarded the 2009 Nobel Prize in Physiology or Medicine for “the discovery of how chromosomes are protected by telomeres and the enzyme telomerase” (http://nobelprize.org/nobel_prizes/medicine/laureates/2009/).María Blasco, Director of the Centro Nacional de Investigaciones Oncológicas (CNIO; Spanish National Cancer Research Centre; Madrid, Spain), is similarly optimistic about the prospect of telomere testing becoming a routine health test. “As an analogy, telomere length testing could be similar to what has occurred with cholesterol tests, which went in [the] early 80s from being an expensive test for which no direct drug treatment was available to being a routine test in general health check-ups,” she said.Carol Greider, Professor and Director of Molecular Biology and Genetics at Johns Hopkins University (Baltimore, Maryland, USA) and co-recipient of the 2009 Nobel Prize with Blackburn, however, does not believe that testing is ready for widespread use, although she agreed that telomere length can reveal a lot about disease and is an important subject for research. “Certainly, right now, I think it''s very premature to be offering this kind of testing to the public. I don''t think that the research has yet told us about the risks, what we can actually say statistically with high confidence, so it''s unclear to me if there is any real value to the general public to testing telomeres,” she said.Blasco is Chief Scientific Advisor to Life Length, a CNIO spin-off company that launched its test last year to a storm of media attention. “For some scientists, there is always a question that needs to be solved or has not been sufficiently evaluated,” she said. “We have lots of information showing that telomere length is important for understanding ageing and certain diseases [...] New technologies have been developed that allow us now to measure telomere length in a large scale using a simple blood sample or a spit sample. The fact that the technology is here and the science is here makes this a good moment to market this testing.”“We have lots of information showing that telomere length is important for understanding ageing and certain diseases [...] the technology is here and the science is here”Apart from discussion of the science, companies that offer telomere testing are also encountering scepticism from ethicists and other scientists about the value of telomere-length testing for normal healthy people.Lansdorp, who is a medical doctor by training, thinks that practitioners are not yet ready to use and interpret the tests. “It''s a new field and there are good clinical papers out there, but the irony is that our work [that] has highlighted the value of these tests for specific clinical conditions [is] now being used [...] to make the point that it''s really important to have your telomeres tested, but the dots are not connected by a straight line,” he said.Jonathan Stein, Director of Science and Research at SpectraCell Laboratories (Houston, Texas, USA)—which offers its US $250 telomere test as an extension of its nutritional product line that is sold to family physicians, chiropractors and naturopaths—said that there has only really been demand for the telomere test from his company among physicians and their spouses, but not for use in the clinic. “Doctors are incredibly curious about [the test] and then when we do follow-ups in general, they tell us it''s interesting and they know it''s valuable, but they''re not entirely sure what it means to people. Where we go from the bench to bedside, there seems to be a real sticking point,” he said, adding that he thinks demand will increase as the public becomes increasingly educated about telomeres and health.Arthur Caplan, Professor of Bioethics and Director of the Center for Bioethics at the University of Pennsylvania (Philadelphia, USA), is not clear that even an educated public will be interested in what the test can tell them. “We don''t have any great reason to think that people will be interested in knowing facts about themselves [...] if they can''t do anything about it. I think most people would say ''I''m not going to spend money on this until you tell me if there''s something I can do to slow this process or expand my life''.” As such, he thinks that companies that are getting in early to ''cash in'' on the novelty of telomere testing are unlikely to see huge success, partly because the science is not yet settled.Calvin Harley, President and Chief Science Officer at Telome Health, disagrees. He thinks that two things will drive demand for telomere testing: the growing number of clinical studies validating the utility of the test, and the growing interest in lifestyle changes and interventions that help to maintain telomeres....two things will drive demand for telomere testing: the growing number of clinical studies [...] and [...] interest in lifestyle changes and interventions that help maintain telomeresBut these are early days. Jerry Shay, Professor of Cell Biology and Neuroscience at the University of Texas Southwestern Medical Center (Dallas, USA) and an adviser to the company Life Length, said that early adopters are likely to be the health conscious and the curious. “Some people will say, ''Well, look, I had my telomeres measured: I''m a 60 year old with 50-year-old telomeres'',” he explained. “It will have ''My telomeres are longer than your telomeres'' type of cocktail talk appeal. That''s fine. I have no problem with that as long as we can follow this sort of population and individuals over decades.”“It will have ''My telomeres are longer than your telomeres'' type of cocktail talk appeal [...] I have no problem with that as long as we can follow this sort of population and individuals...”Shay''s last point is the key—research and data collection. Even those commercializing telomere-length tests agree that our understanding of telomere biology, although extensive, is incomplete and that we have yet to unpick fully the links between telomeres and disease. Stefan Kiechl, a telomere researcher in the Department of Neurology at Innsbruck Medical University (Austria), published an article last year on telomere length and cancer (Willeit et al, 2010). “The appealing thing with telomere length measurements is that they allow the estimation of the biological—in contrast to the chronological—age of an organism. This was previously not possible. Moreover, long telomere length has been linked with a low risk of advanced atherosclerosis, cardiovascular disease and cancer, and, vice versa, short telomere length is associated with a higher risk of these diseases.”But, he said that problems remain to be resolved, such as whether telomere length can only be measured in cells that are readily available, such as leukocytes, and whether telomere length in leukocytes varies substantially from telomere length in other tissues and cells. “Moreover, there is still insufficient knowledge on which lifestyle behaviours and other factors affect telomere length,” he concluded.This might be a bumpy road. When Life Length announced its launch in May, newspapers carried headlines such as ''The £400 test that tells you how long you''ll live'', reporting: “A blood test that can show how fast someone is ageing—and offers the tantalizing possibility of estimating how long they have left to live—is to go on sale to the general public in Britain later this year” (Connor, 2011).The story was catchy, but Life Length officials are determined to explain that, despite the name of the company, its tests do not predict longevity for individuals. Blasco said that the word ''life'' in the name is meant as an analogy between telomeres and life. “A British newspaper chose to use this headline, but the company name has no intention to predict longevity,” she said. Instead, the name refers to extensive research correlating the shortened chromosome tips with the risk for certain diseases and personal habits, such as smoking, obesity, lack of exercise and stress, Blasco explained.Life Length''s test measures the abundance of short telomeres, as they claim that there is genetic evidence that short telomeres are the ones that are relevant to disease. “The preliminary results are exciting: we are observing that the percent of short telomeres with increasing age is more divergent between individuals than average telomere length for the same group of individuals,” Blasco explained. “This is exactly what you would expect from a parameter [abundance of short telomeres] that reflects the effects of environmental factors and lifestyle on people''s telomeres.” She noted that being in a lower quartile of average telomere length and the higher quartile of abundance of short telomeres would indicate that telomeres are shorter than normal for a given age, which has been correlated with a higher risk of developing certain diseases.So, what can be done about an abundance of short telomeres? Lansdorp said that, as a physician, he would be hard pressed to know what to tell patients to do about it. “The best measure of someone''s age and life expectancy is the date on their birth certificate. Telomere length, as a biomarker, shows a clear correlation with age at the population level. For an individual the value of telomere length is very limited,” he said. “I suspect there''s going to be a lot of false alarms based on biological variation as well as measurement errors using these less accurate tests.”“The best measure of someone''s age and life expectancy is the date on their birth certificate. [...] For an individual the value of telomere length is very limited”Harley, however, said that if telomere length were perfectly correlated with age, it would be a useless biomarker, except for in forensic work. “The differences in telomere length between individuals at any given age is where the utility lies [...] people with shorter telomeres are at higher risk for morbidity and mortality. In addition, there is emerging data suggesting that people with shorter telomeres respond differently to certain drugs than people with longer telomeres. This fits into the paradigm of personalized medicine,” he said....if telomere length were perfectly correlated with age, it would be a useless biomarker, except for in forensic workWhile he was at Geron Corporation, Harley was the lead discoverer of telomerase activators purified from the root of Astragalus membranaceus. Harley, Blasco and colleagues have published two peer-reviewed papers on one of those molecules, TA-65—one in humans and the other in mice (de Jesus et al, 2011; Harley et al, 2011). Both showed positive effects on certain health measures, and Blasco''s lab found that mice treated with TA-65 had improved health status compared with those given a placebo. “However, we did not see significant effects on longevity,” Blasco said.In the meantime, researchers are squabbling about the techniques used by the testing companies. Greider maintains that Flow-FISH (fluorescence in situ hybridization), which was developed by Lansdorp, is the gold standard used by clinical researchers and that it is the most reliable technique. Harley argues that the quantitative real-time (qRT)-PCR assay developed by the Blackburn lab is just as reliable, and easier to scale-up for commercial use. Blasco pointed out that, similarly to its rivals, the qFISH used by Life Length offers measurements of average telomere length, but that it is the only company to report the percentage of short telomeres in individual cells. In the end, Lansdorp suggested that the errors inherent in the tests, along with biological variations and cost, should give healthy people pause for thought about being tested.Ultimately, whichever test for telomere length is used and whatever the results can tell us about longevity and health, it is unlikely that manipulating telomere length will unlock the fountain of youth, à la Spanish explorer Juan Ponce de León y Figueroa (1474–1521). Nevertheless, telomere testing could become a key diagnostic tool for getting a few more years out of life, and it could motivate people to follow healthier lifestyles. As Kiechl pointed out, “[t]here is convincing evidence that calculation of an individual''s risk of cardiovascular disease [...] substantially enhances compliance for taking medicines and the willingness to change lifestyle. Knowing one''s biological age may well have similar favourable effects.”     

Coordinated expression in chronically unconscious persons.

The clinically described ''persistent vegetative state'' (PVS), consists of wakefulness unaccompanied by any evidence of the subject''s awareness of self or environment. Past studies from our own and other laboratories have used positron emission tomography (PET) to study brain metabolism in approximately 20 such patients during wakeful periods. All those efforts identified global cerebral glucose metabolism at or below levels encountered during deep barbiturate anaesthesia. Nevertheless, the clinical literature includes rare reports of relatively isolated cognitive functions expressed by PVS patients late in their course. The observation raises the question of whether such activity reflects awareness or unconscious automatic behaviour. We employed magnetometry (MEG), PET scanning, MR imaging and 24-hour EEG recordings to evaluate three patients clinically vegetative between six months and 20 years after onset. Neither meticulous clinical examinations nor 24-hour EEG and video monitoring provided any hint of cognitive interaction in any subject. Nevertheless, patient 1 uttered single words once every 48 hours or more; patient 2 frequently expressed coordinated, non-purposeful, non-dystonic movements in arms and/or legs; and, patient 3 expressed strong emotional negativity without motor responses to noxious stimuli with occasional quieting in response to prosodic stimuli. All patients had whole-brain averaged global metabolism levels below 50% of normal. Patient 1, however, demonstrated preserved islands of increased metabolism in the posterior frontal and posterior temporal lobes, as well as MEG activations of Heschl''s gyrus all located in the left hemisphere. In patient 2, selected increased metabolism was confined to the frontal poles and related subcortical structures. MRI in patient 3 demonstrated severe, bilateral post-traumatic cerebral atrophy. PET metabolism was diffusely reduced to 40% of normal but MEG evoked potentials indicated early and late sensory processing with abnormal later evoked components. The correlation of fragmentary behaviour with preserved metabolic and physiologic activity in cortical and subcortical regions known to support specific modular functions is novel. The finding demonstrates the capacity of severely damaged brains to partially express surviving modular functions without evidence of integrative processes that would be necessary to produce consciousness. We conclude that the mere expression of isolated neuropsychologic activity by isolated modules is insufficient to generate consciousness in overwhelmingly damaged brains.