Missing something? Codon aversion as a new character system in phylogenetics

Although many studies have documented codon usage bias in different species, the importance of codon usage in a phylogenetic framework remains largely unknown. We demonstrate that a phylogenetic signal is present in the codon usage and non‐usage biases of 17 717 orthologues evaluated across 72 tetrapod species using a simple parsimony analysis of a binary matrix of codon characters. Phylogenies estimated using stop codons were more congruent with previous hypotheses than phylogenies based on any other single codon or a combination of codons. Although each codon is present in every species, specific genes have different codon preferences and may or may not use every possible codon. This observation allowed us to map the pattern of codon usage and non‐usage across the topology. These results suggest that codon usage is phylogenetically conserved across shallow and deep levels within tetrapods.     

Does acute exposure to mobile phones affect human attention?

Recent studies have indicated that acute exposure to low level radiofrequency (RF) electromagnetic fields generated by mobile phones affects human cognition. However, the relatively small samples used, in addition to methodological problems, make the outcomes of these studies difficult to interpret. In our study we tested a large sample of volunteers (168) using a series of cognitive tasks apparently sensitive to RF exposure (a simple reaction task, a vigilance task, and a subtraction task). Participants performed those tasks twice, in two different sessions. In one session they were exposed to RFs, with half of subjects exposed to GSM signals and the other half exposed to CW signals, while in the other session they were exposed to sham signals. No significant effects of RF exposure on performance for either GSM or CW were found, independent of whether the phone was positioned on the left or on the right side.     

Plants on red alert: do insects pay attention?

Two recent hypotheses have proposed that non-green plant colouration evolved as a defence against herbivores, either as protective colouration promoting handicap signals indicating plant fitness or by undermining their crypsis. The handicap hypothesis posits a co-evolutionary process between plants and herbivores, whereas the anti-crypsis hypothesis suggests that an arms race between insects and plants is the evolutionary mechanism. Both explanations assume that insects are the evolutionary origin causing plants' colouration. Here, we propose a different hypothesis, termed the "Defence Indication hypothesis". This idea focuses on the multiple protective functions of anthocyanins and carotenoids as pigments, and suggests that plant colouration evolved primarily in response to various stressors. Because pigments and defensive compounds share a common biosynthesis, the production of pigments also provides elevated defensive strengths against herbivores, a process termed priming. In effect, the Defence Indication hypothesis predicts that pleiotropic effects of the pigments and, more generally, plants' shared defence responses, explain why insects might react to plant colouration.     

Why is joint attention a pivotal skill in autism?

Joint attention abilities play a crucial role in the development of autism. Impairments in joint attention are among the earliest signs of the disorder and joint attention skills relate to outcome, both in the 'natural course' of autism and through being targeted in early intervention programmes. In the current study, concurrent and longitudinal associations between joint attention and other social communication abilities measured in a sample of infants with autism and related pervasive developmental disorders at age 20 months, and language and symptom severity at age 42 months, were examined. Extending the findings from previous studies, joint attention ability was positively associated with language gains and (lower) social and communication symptoms, and imitation ability was also positively associated with later language. Some specificity in the association between different aspects of joint attention behaviours and outcome was found: declarative, triadic gaze switching predicted language and symptom severity but imperative, dyadic eye contact behaviours did not. Further, although joint attention was associated with later social and language symptoms it was unrelated to repetitive and stereotyped symptoms, suggesting the latter may have a separate developmental trajectory. Possible deficits in psychological and neurological processes that might underlie the impaired development of joint attention in autism are discussed.     

Does conditioned taste aversion learning in the pond snail Lymnaea stagnalis produce conditioned fear?

In conditioned taste aversion (CTA) training performed on the pond snail Lymnaea stagnalis, a stimulus (the conditional stimulus, CS; e.g., sucrose) that elicits a feeding response is paired with an aversive stimulus (the unconditional stimulus, US) that elicits the whole-body withdrawal response and inhibits feeding. After CTA training and memory formation, the CS no longer elicits feeding. We hypothesize that one reason for this result is that after CTA training the CS now elicits a fear response. Consistent with this hypothesis, we predict the CS will cause (1) the heart to skip a beat and (2) a significant change in the heart rate. Such changes are seen in mammalian preparations exposed to fearful stimuli. We found that in snails exhibiting long-term memory for one-trial CTA (i.e., good learners) the CS significantly increased the probability of a skipped heartbeat, but did not significantly change the heart rate. The probability of a skipped heartbeat was unaltered in control snails given backward conditioning (US followed by CS) or in snails that did not acquire associative learning (i.e., poor learners) after the one-trial CTA training. These results suggest that as a consequence of acquiring CTA, the CS evokes conditioned fear in the conditioned snails, as evidenced by a change in the nervous system control of cardiac activity.     

Bottom�Cup attention: pulsed PCA transform and pulsed cosine transform

In this paper we propose a computational model of bottom–up visual attention based on a pulsed principal component analysis (PCA) transform, which simply exploits the signs of the PCA coefficients to generate spatial and motional saliency. We further extend the pulsed PCA transform to a pulsed cosine transform that is not only data-independent but also very fast in computation. The proposed model has the following biological plausibilities. First, the PCA projection vectors in the model can be obtained by using the Hebbian rule in neural networks. Second, the outputs of the pulsed PCA transform, which are inherently binary, simulate the neuronal pulses in the human brain. Third, like many Fourier transform-based approaches, our model also accomplishes the cortical center-surround suppression in frequency domain. Experimental results on psychophysical patterns and natural images show that the proposed model is more effective in saliency detection and predict human eye fixations better than the state-of-the-art attention models.     

Neural network model of selective visual attention using Hodgkin–Huxley equation

We propose a mathematical model of selective visual attention using a two-layered neural network with neurons described by the Hodgkin–Huxley equation in order to investigate part of the assumption proposed by Desimone and Duncan. The neural network consists of a layer of hippocampal formation and of visual cortex. A frequency of firing and a firing time for each neuron and also a correlation of the firing times between neurons are calculated numerically to clarify an attention state, a nonattention state, and an attention shift. We find that synchronous phenomena occur not only for the frequency but also for the firing time between the neurons in the hippocampal formation and those in a part of the visual cortex in our model. It also turns out that the attention shift is performed quickly in our model.Acknowledgements We are grateful to T. Omori for his valuable discussions and comments. K. K. was partially supported by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists. This work was partially supported by Grant-In-Aid for Scientific Research No. 13680383 from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.     

The planning of action: can one separate attention from intention?

Attention and motor preparation are two intimately linked processes. However, they can be dissociated in the laboratory in order to study their neuronal basis. Behavioral neurophysiology has thus shown that neurons that discharge in relation with attention or with motor preparation (or intention) exist in a variety of brain regions in the monkey, especially the prefrontal and premotor cortices. When examined more carefully, these two regions appear different in both the proportion of cells that respond during attention versus intention, and in the information coded in the so-called "preparatory activity". This activity reflects sensory selection in the prefrontal cortex (spatial attention/memory), motor selection in the premotor cortex. Furthermore, two regions in the dorsal aspect of premotor cortex can be distinguished on the basis of their relative involvement in attention: a rostral (anterior) region, functionally close to prefrontal cortex, and a caudal one, which appears functionally close to motor cortex. Using an experimental design derived from monkey experiments, a functional magnetic resonance imaging (fMRI) study recently indicated that the functional specialization within the premotor cortex is similar in monkey and man.     

Role of IKK/NF-κB signaling in extinction of conditioned place aversion memory in rats

The inhibitor κB protein kinase/nuclear factor κB (IKK/NF-κB) signaling pathway is critical for synaptic plasticity. However, the role of IKK/NF-κB in drug withdrawal-associated conditioned place aversion (CPA) memory is unknown. Here, we showed that inhibition of IKK/NF-κB by sulphasalazine (SSZ; 10 mM, i.c.v.) selectively blocked the extinction but not acquisition or expression of morphine-induced CPA in rats. The blockade of CPA extinction induced by SSZ was abolished by sodium butyrate, an inhibitor of histone deacetylase. Thus, the IKK/NF-κB signaling pathway might play a critical role in the extinction of morphine-induced CPA in rats and might be a potential pharmacotherapy target for opiate addiction.     

To what extent are emotional visual stimuli processed without attention and awareness?

In the past few years, important contributions have been made to the study of emotional visual perception. Researchers have reported responses to emotional stimuli in the human amygdala under some unattended conditions (i.e. conditions in which the focus of attention was diverted away from the stimuli due to task instructions), during visual masking and during binocular suppression. Taken together, these results reveal the relative degree of autonomy of emotional processing. At the same time, however, important limitations to the notion of complete automaticity have been revealed. Effects of task context and attention have been shown, as well as large inter-subject differences in sensitivity to the detection of masked fearful faces (whereby briefly presented, target fearful faces are immediately followed by a neutral face that 'masks' the initial face). A better understanding of the neural basis of emotional perception and how it relates to visual attention and awareness is likely to require further refinement of the concepts of automaticity and awareness.     

The remote roots of consciousness in fruit‐fly selective attention?

A mechanistic study of consciousness need not be confined to human complexity. Other animals also display key behaviors and responses that have long been intimately tied to the measure of consciousness in humans. Among them are some very well-defined and measurable endpoints: selective attention, sleep and general anesthesia. That these three variables associated with changes in consciousness might exist even in a fruit-fly does not necessarily imply that a fly is "conscious", but it does suggest that some of the problems central to the field of consciousness studies could be investigated in a model organism such as Drosophila melanogaster. Demonstrating suppression of unattended stimuli, which is central to attention studies in humans, is now possible in Drosophila by measuring neural correlates of visual selection. By combining such studies with an eventual understanding of suppression in other arousal states in the fly, such as sleep and general anesthesia, we might be unraveling mechanisms relevant to consciousness as well.     

Does food play a prominent role in visual attention to disgusting stimuli?

Journal of Ethology - Disgust is a basic emotion which protects individuals from potential contamination. It is hypothesized that disgust evolved primarily as a mechanism against oral contamination...     

Where do i look? From attention to action in the frontal eye field

The frontal eye field (FEF) has been known as a key player in the generation of saccade motor commands and in the allocation of spatial attention. In this issue of Neuron, Schafer and Moore demonstrate that FEF microstimulation enhances the effect of a position illusion induced by visual motion on saccades. This finding suggests that FEF activity can modulate the deployment of spatial attention, which in turn can alter saccade motor commands.     

Through a barn owl’s eyes: interactions between scene content and visual attention

In this study we investigated visual attention properties of freely behaving barn owls, using a miniature wireless camera attached to their heads. The tubular eye structure of barn owls makes them ideal subjects for this research since it limits their eye movements. Video sequences recorded from the owl’s point of view capture part of the visual scene as seen by the owl. Automated analysis of video sequences revealed that during an active search task, owls repeatedly and consistently direct their gaze in a way that brings objects of interest to a specific retinal location (retinal fixation area). Using a projective model that captures the geometry between the eye and the camera, we recovered the corresponding location in the recorded images (image fixation area). Recording in various types of environments (aviary, office, outdoors) revealed significant statistical differences of low level image properties at the image fixation area compared to values extracted at random image patches. These differences are in agreement with results obtained in primates in similar studies. To investigate the role of saliency and its contribution to drawing the owl’s attention, we used a popular bottom-up computational model. Saliency values at the image fixation area were typically greater than at random patches, yet were only 20% out of the maximal saliency value, suggesting a top-down modulation of gaze control.     

Is high prevalence of vitamin D deficiency a correlate for attention deficit hyperactivity disorder?

The aim of the study was to determine the association between vitamin D and attention deficit hyperactivity disorder (ADHD), and difference in the level of vitamin D in ADHD children and control. This a case–control study carried out in school health and primary health care clinics. A total of 1,331 children and adolescents who were diagnosed with ADHD based on clinical criteria and standardized questionnaires were enrolled in this study and were matched with 1,331 controls, aged 5–18 years old. Data on body mass index (BMI), clinical biochemistry variables including serum 25-hydroxyvitamin D were collected. The study found significant association between ADHD and vitamin D deficiency after adjusting for BMI and sex (adj. OR 1.54; 95 % CI 1.32–1.81; P < 0.001). Majority of the ADHD children were in the age group 5–10 years (40.7 %), followed by 11–13 years (38.4 %). The proportion of BMI <85th percentile was significantly over represented in ADHD group as compared to healthy control (87.8 vs. 83 %; P < 0.001, respectively), while on the other hand, BMI >95th percentile was over represented in the control than ADHD group (7.6 vs. 4.6 %; P < 0.001, respectively). Mean values of vitamin D (ng/mL) were significantly lower in ADHD children (16.6 ± 7.8) than in healthy children (23.5 ± 9.0) (P < 0.001). There was significant correlation between vitamin D deficiency and age (r = ?0.191, P = 0.001); calcium (r = 0.272, P = 0.001); phosphorous (r = 0.284, P = 0.001); magnesium (r = 0.292, P = 0.001); and BMI (r = 0.498, P = 0.001) in ADHD children. The vitamin D deficiency was higher in ADHD children compared to healthy children.     

Electroencephalographic characteristics of cognitive-specific attention in verbal learning—II: General characteristics of EEG spatial synchronization

Electroencephalograms (EEGs) were recorded in 19 standard derivations in 88 subjects (students) in states of: rest with the eyes open; memorization (learning) of verbal bilingual semantic pairs (Latin and Russian); and recollection (control) of the memorized information. Estimates of EEG coherence in these states were compared using statistical methods for the frequency bands θ, α₁, α₂, β₁, β₂, and γ. The results of this comparison showed that transition from the state of rest to those of memorization and recollection was accompanied by numerous changes in coherence in all the frequency bands. These changes varied in intensity and embrace practically the entire convexital cerebral cortex. Decrease in EEG coherence was predominant during the transition to the memorization state in various frequency bands, whereas during the transition from the rest state to that of recollection, EEG coherence increased in most of the frequency bands except for the band α₂. The reproducibility of this pattern of changes in EEG coherence is confirmed by the results in the subgroups formed by randomly subdividing the subjects into two groups. We think that the observed intense rearrangement of the spatial synchronization of the cortex electrical activity reflects the reorganization of the functional systems of neuronal ensembles to provide efficient memorization and recollection, respectively.