Episodic-like memory: pigeons can report location pecked when unexpectedly asked

Pigeons were tested for their ability to report the location they recently pecked, without prior experience having to do so. They were first pretrained to report the location that they had just pecked. They were then trained on a conditional discrimination to associate yellow and blue samples with vertical and horizontal comparisons, respectively, independent of comparison location. On probe trials in testing, when after choosing a vertical or horizontal line following the yellow or blue sample, the pigeons were ‘asked’ which location they had just pecked, they showed a significant tendency to choose correctly in spite of the fact that location of the correct comparison was incidental to the task. Performing on probe trials is analogous to asking the pigeons an unexpected question about their recent behavior and it is similar to the episodic memory question asked of humans, “What did you have for breakfast this morning?”.     

Learning related interactions among neuronal systems involved in memory processes

Functional neuroimaging techniques using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have provided new insights in our understanding of brain function from the molecular to the systems level. While subtraction strategy based data analyses have revealed the involvement of distributed brain regions in memory processes, covariance analysis based data analysis strategies allow functional interactions between brain regions of a neuronal network to be assessed. The focus of this chapter is to (1) establish the functional topography of episodic and working memory processes in young and old normal volunteers, (2) to assess functional interactions between modules of networks of brain regions by means of covariance based analyses and systems level modelling and (3) to relate neuroimaging data to the underpinning neural networks. Male normal young and old volunteers without neurological or psychiatric illness participated in neuroimaging studies (PET, fMRI) on working and episodic memory. Distributed brain areas are involved in memory processes (episodic and working memory) in young volunteers and show much of an overlap with respect to the network components. Systems level modelling analyses support the hypothesis of bihemispheric, asymmetric networks subserving memory processes and revealed both similarities in general and differences in the interactions between brain regions during episodic encoding and retrieval as well as working memory. Changes in memory function with ageing are evident from studies in old volunteers activating more brain regions compared to young volunteers and revealing more and stronger influences of prefrontal regions. We finally discuss the way in which the systems level models based on PET and fMRI results have implications for the understanding of the underlying neural network functioning of the brain.     

Episodic Molecular Evolution of Pituitary Growth Hormone in Cetartiodactyla

The sequence of growth hormone (GH) is generally strongly conserved in mammals, but episodes of rapid change occurred during the evolution of primates and artiodactyls, when the rate of GH evolution apparently increased substantially. As a result the sequences of higher primate and ruminant GHs differ markedly from sequences of other mammalian GHs. In order to increase knowledge of GH evolution in Cetartiodactyla (Artiodactyla plus Cetacea) we have cloned and characterized GH genes from camel (Camelus dromedarius), hippopotamus (Hippopotamus amphibius), and giraffe (Giraffa camelopardalis), using genomic DNA and a polymerase chain reaction technique. As in other mammals, these GH genes comprise five exons and four introns. Two very similar GH gene sequences (encoding identical proteins) were found in each of hippopotamus and giraffe. The deduced sequence for the mature hippopotamus GH is identical to that of dolphin, in accord with current ideas of a close relationship between Cetacea and Hippopotamidae. The sequence of camel GH is identical to that reported previously for alpaca GH. The sequence of giraffe GH is very similar to that of other ruminants but differs from that of nonruminant cetartiodactyls at about 18 residues. The results demonstrate that the apparent burst of rapid evolution of GH occurred largely after the separation of the line leading to ruminants from other cetartiodactyls.     

Laterality enhances cognition in Australian parrots

Cerebral lateralization refers to the division of information processing in either hemisphere of the brain and is a ubiquitous trait among vertebrates and invertebrates. Given its widespread occurrence, it is likely that cerebral lateralization confers a fitness advantage. It has been hypothesized that this advantage takes the form of enhanced cognitive function, potentially via a dual processing mechanism whereby each hemisphere can be used to process specific types of information without contralateral interference. Here, we examined the influence of lateralization on problem solving by Australian parrots. The first task, a pebble-seed discrimination test, was designed for small parrot species that feed predominately on small seeds, which do not require any significant manipulation with the foot prior to ingestion. The second task, a string-pull problem, was designed for larger bodied species that regularly use their feet to manipulate food objects. In both cases, strongly lateralized individuals (those showing significant foot and eye biases) outperformed less strongly lateralized individuals, and this relationship was substantially stronger in the more demanding task. These results suggest that cerebral lateralization is a ubiquitous trait among Australian parrots and conveys a significant foraging advantage. Our results provide strong support for the enhanced cognitive function hypothesis.     

Knowledge acquisition, semantic text mining, and security risks in health and biomedical informatics

Computational techniques have been adopted in medi-cal and biological systems for a long time. There is no doubt that the development and application of computational methods will render great help in better understanding biomedical and biological functions. Large amounts of datasets have been produced by biomedical and biological experiments and simulations. In order for researchers to gain knowledge from origi- nal data, nontrivial transformation is necessary, which is regarded as a critical link in the chain of knowledge acquisition, sharing, and reuse. Challenges that have been encountered include: how to efficiently and effectively represent human knowledge in formal computing models, how to take advantage of semantic text mining techniques rather than traditional syntactic text mining, and how to handle security issues during the knowledge sharing and reuse. This paper summarizes the state-of-the-art in these research directions. We aim to provide readers with an introduction of major computing themes to be applied to the medical and biological research.     

Evolution of Growth Hormone in Primates: The GH Gene Clusters of the New World Monkeys Marmoset (Callithrix jacchus) and White-Fronted Capuchin (Cebus albifrons)

The GH gene cluster in marmoset, Callithrix jacchus, comprises eight GH-like genes and pseudogenes and appears to have arisen as a consequence of gene duplications occurring independently of those leading to the human GH gene cluster. We report here the complete sequence of the marmoset GH gene locus, including the intergenic regions and 5′ and 3′ flanking sequence, and a study of the multiple GH-like genes of an additional New World monkey (NWM), the white-fronted capuchin, Cebus albifrons. The marmoset sequence includes 945 nucleotides (nt) of 5′ flanking sequence and 1596 nt of 3′ flanking sequence that are “unique”; between these are eight repeat units, including the eight GH genes/pseudogenes. The breakpoints between these repeats are very similar, indicating a regular pattern of gene duplication. These breakpoints do not correspond to those found in the much less regular human GH gene cluster. This and phylogenetic analysis of the repeat units within the marmoset gene cluster strongly support the independent origin of these gene clusters, and the idea that the episode of rapid evolution that occurred during GH evolution in primates preceded the gene duplications. The marmoset GH gene cluster also differs from that of human in having fewer and more evenly distributed Alu sequences (a single pair in each repeat unit) and a “P-element” upstream of every gene/pseudogene. In human there is no P-element upstream of the gene encoding pituitary GH, and these elements have been implicated in placental expression of the other genes of the cluster. The GH gene clusters in marmoset and capuchin appear to have arisen as the consequence of a single-gene duplication event, but in capuchin there was then a remarkable expansion of the GH locus, giving at least 40 GH-like genes and pseudogenes. Thus even among NWMs the GH gene cluster is very variable. [Reviewing Editor: Nicolas Galtier]     

Functional imaging of memory processes in humans: positron emission tomography and functional magnetic resonance imaging

Human memory is not a unitary function; it consists of multiple memory systems, with different characteristics and specialisations that are implemented in the brain. The cognitive neuroscience of human memory tries to comprehend how we encode, store, and retrieve memory items within and across those systems. The emergence of functional neuroimaging techniques offered the unprecedented opportunity to directly observe the brain regions engaged in memory functions. Brain imaging techniques can roughly be divided into those measuring the electric or magnetic fields generated by neuronal activity (EEG, magnetencephalography [MEG]) and those measuring the haemodynamic or metabolic sequelae of neuronal activity (positron emission tomography [PET], functional magnetic resonance imaging [fMRI]). Out of these techniques, the following two will be discussed in detail: fMRI and PET. Although functional neuroimaging is able to acquire images of the brain engaged in consolidating or retrieving memories, these processes are not clearly visible in the data. Statistical techniques are needed to reduce the complexity of the data and to extract the processes of interest. This article outlines the experimental and analytical procedures of neuroimaging studies with PET and fMRI. We will use a PET-study on episodic memory in human volunteers to illustrate design, analysis, and interpretation of functional imaging studies on memory.     

Episodic sitewise positive selection on the signal recognition particle protein Ffh in Actinobacteria

In this work, we report a case of episodic sitewise positive selection acting on the highly conserved SRP protein Ffh in Actinobacteria. An elevated non-synonymous to synonymous mutation ratio (ω) was observed along the non-terminal branches of the species tree, which contained 11 Actinobacteria species, where positively selected residues were frequently observed within the signal sequence-binding domain. Together with the estimated lineage-specific ω ratios for several core components in the major protein translocation systems, our data suggest that this positive selection might be partially driven by the diversification of signal sequences.     

Photosynthetic symbioses in animals

Animals acquire photosynthetically-fixed carbon by forming symbioseswith algae and cyanobacteria. These associations are widespreadin the phyla Porifera (sponges) and Cnidaria (corals, sea anemonesetc.) but otherwise uncommon or absent from animal phyla. Itis suggested that one factor contributing to the distributionof animal symbioses is the morphologically-simple body planof the Porifera and Cnidaria with a large surface area:volumerelationship well-suited to light capture by symbiotic algaein their tissues. Photosynthetic products are released fromliving symbiont cells to the animal host at substantial rates.Research with algal cells freshly isolated from the symbiosessuggests that low molecular weight compounds (e.g. maltose,glycerol) are the major release products but further researchis required to assess the relevance of these results to thealgae in the intact symbiosis. Photosynthesis also poses risksfor the animal because environmental perturbations, especiallyelevated temperature or irradiance, can lead to the productionof reactive oxygen species, damage to membranes and proteins,and ‘bleaching’, including breakdown of the symbiosis.The contribution of non-photochemical quenching and membranelipid composition of the algae to bleaching susceptibility isassessed. More generally, the development of genomic techniquesto help understand the processes underlying the function andbreakdown of function in photosynthetic symbioses is advocated. Key words: Bleaching, Chlorella, Cnidaria, coral, metabolite profiling, nutrient release, photosynthesis, Symbiodinium, symbiosis, symbiotic algae     

Antiviral silencing in animals

RNA silencing or RNA interference (RNAi) refers to the small RNA-guided gene silencing mechanism conserved in a wide range of eukaryotic organisms from plants to mammals. As part of this special issue on the biology, mechanisms and applications of RNAi, here we review the recent advances on defining a role of RNAi in the responses of invertebrate and vertebrate animals to virus infection. Approximately 40 miRNAs and 10 RNAi suppressors encoded by diverse mammalian viruses have been identified. Assays used for the identification of viral suppressors and possible biological functions of both viral miRNAs and suppressors are discussed. We propose that herpes viral miRNAs may act as specificity factors to initiate heterochromatin assembly of the latent viral DNA genome in the nucleus.     

Taxonomic counts of cognition in the wild

In 1985, Kummer & Goodall pleaded for an ecology of intelligence and proposed that innovations might be a good way to measure cognition in the wild. Counts of innovation per taxonomic group are now available in hundreds of avian and primate species, as are counts of tactical deception, tool use and social learning. Robust evidence suggests that innovation rate and its neural correlates allow birds and mammals to cope better with environmental change. The positive correlations between taxonomic counts, and the increasing number of cognitive and neural measures found to be associated with ecological variables, suggest that domain general processes might be more pervasive than previously thought in the evolution of intelligence.     

Positive feedback loops sustain repeating bursts in neuronal circuits

Voluntary movements in animals are often episodic, with abrupt onset and termination. Elevated neuronal excitation is required to drive the neuronal circuits underlying such movements; however, the mechanisms that sustain this increased excitation are largely unknown. In the medicinal leech, an identified cascade of excitation has been traced from mechanosensory neurons to the swim oscillator circuit. Although this cascade explains the initiation of excitatory drive (and hence swim initiation), it cannot account for the prolonged excitation (10–100 s) that underlies swim episodes. We present results of physiological and theoretical investigations into the mechanisms that maintain swimming activity in the leech. Although intrasegmental mechanisms can prolong stimulus-evoked excitation for more than one second, maintained excitation and sustained swimming activity requires chains of several ganglia. Experimental and modeling studies suggest that mutually excitatory intersegmental interactions can drive bouts of swimming activity in leeches. Our model neuronal circuits, which incorporated mutually excitatory neurons whose activity was limited by impulse adaptation, also replicated the following major experimental findings: (1) swimming can be initiated and terminated by a single neuron, (2) swim duration decreases with experimental reduction in nerve cord length, and (3) swim duration decreases as the interval between swim episodes is reduced.     

Foresight in cultural evolution

Critics of Darwinian cultural evolution frequently assert that whereas biological evolution is blind and undirected, cultural change is directed or guided by people who possess foresight, thereby invalidating any Darwinian analysis of culture. Here I show this argument to be erroneous and unsupported in several respects. First, critics commonly conflate human foresight with supernatural clairvoyance, resulting in the premature rejection of Darwinian cultural evolution on false logical grounds. Second, the presence of foresight is perfectly consistent with Darwinian evolution, and is found in biology, in the form of open, teleonomic processes such as genetically-biased behavioural learning. Finally, empirical evidence from the social sciences suggests that cultural change appears far less guided and directed, and human foresight far less accurate, than is commonly assumed.

Carbohydrates and fertilization in animals

A frequently used mechanism for sperm-egg recognition in many species involves complementary protein-carbohydrate interaction. The usual paradigm includes complex glycoconjugates in reproductive tract fluids or on the eggs which are recognized by carbohydrate-binding proteins on the sperm surface. Various glycoconjugates are utilized in the steps of sperm capacitation, sperm binding to the egg extracellular matrix and vitelline membrane and induction of the acrosome reaction. Several types of complex glycoconjugates are involved in these processes, including proteoglycans, lactosaminoglycans, sulfated fucose-containing glycoconjugates, and glycoproteins. There appear to be some structural similarities between active glycoconjugates; they are large in molecular weight and complex, and they are often sulfated, fucosylated, and attached to a protein through serine or threonine residues. In some species, the protein core of the glycoconjugates also participates in the interaction by limiting the binding of carbohydrates to sperm only of the relevant species, likely by providing the proper steric arrangement for the interaction. In other cases the protein core seems to serve more as a crosslinker of the carbohydrate moieties. This review discusses the types of glycoconjugates implicated in fertilization and the complementary lectin-like proteins found on sperm.     

Homoploid hybrid speciation in animals

Among animals, evidence for homoploid hybrid speciation (HHS, i.e. the creation of a hybrid lineage without a change in chromosome number) was limited until recently to the virgin chub, Gila seminuda, and some controversial data in support of hybrid status for the red wolf, Canis rufus. This scarcity of evidence, together with pessimistic attitudes among zoologists about the evolutionary importance of hybridisation, prompted the view that HHS is extremely rare among animals, especially as compared with plants. However, in recent years, the literature on animal HHS has expanded to include several new putative examples in butterflies, ants, flies and fishes. We argue that this evidence suggests that HHS is far more common than previously thought and use it to provide insights into some of the genetic and ecological aspects associated with this type of speciation among animals.     

Perception of Environmental Threat in the Shadow of War: The Effect of Future Orientation

People may express high concern for global warming or environmental degradation, but when forced to evaluate the severity of environmental threats in relation to other threats, environmental threats are pushed to the bottom of the list. The present study was based on the premise that prioritizing threats involves, inter alia, hierarchizing the threats according to their perceived temporal proximity and since environmental threats are perceived, relative to other threats, as more temporally distant, they rank low. Future orientation (FO) is an individual-difference variable that describes the tendency to take into account temporally distant considerations. We predicted that environmental threats would be evaluated as more severe by individuals who were more future-oriented. The strongest effect of FO was found to be on concern about global warming and environmental degradation. This indicated that environmental threats were perceived as temporally farthest and, not surprisingly, received the lowest priority. External security threat was a top-priority; its severity evaluation was uncorrelated to FO, indicating that it was perceived as temporally closest. These evaluations significantly affected environmental attitudes and behavior. The implications on promoting environmental behavior in the presence of ever-existing shorter-term existential threats are discussed.     

Adaptations for social cognition in the primate brain

Studies of the factors affecting reproductive success in group-living monkeys have traditionally focused on competitive traits, like the acquisition of high dominance rank. Recent research, however, indicates that the ability to form cooperative social bonds has an equally strong effect on fitness. Two implications follow. First, strong social bonds make individuals'' fitness interdependent and the ‘free-rider’ problem disappears. Second, individuals must make adaptive choices that balance competition and cooperation—often with the same partners. The proximate mechanisms underlying these behaviours are only just beginning to be understood. Recent results from cognitive and systems neuroscience provide us some evidence that many social and non-social decisions are mediated ultimately by abstract, domain-general neural mechanisms. However, other populations of neurons in the orbitofrontal cortex, striatum, amygdala and parietal cortex specifically encode the type, importance and value of social information. Whether these specialized populations of neurons arise by selection or through developmental plasticity in response to the challenges of social life remains unknown. Many brain areas are homologous and show similar patterns of activity in human and non-human primates. In both groups, cortical activity is modulated by hormones like oxytocin and by the action of certain genes that may affect individual differences in behaviour. Taken together, results suggest that differences in cooperation between the two groups are a matter of degree rather than constituting a fundamental, qualitative distinction.