Brain Behavior and Evolution最新文献

Introduction: Prairie voles (Microtus ochrogaster) are one of the few mammalian species that are monogamous and engage in the biparental rearing of their offspring. Biparental care impacts the quantity and quality of care the offspring receives. The increased attention by the father may translate to heightened tactile contact the offspring receives through licking and grooming.

Methods: In the current study, we used electrophysiological multiunit techniques to define the organization of the perioral representation in the primary somatosensory area (S1) of prairie voles. Functional representations were related to myeloarchitectonic boundaries.

Results: Our results show that most of S1 is occupied by the representation of the contralateral mystacial whiskers and the lower and upper lips. The mystacial vibrissae representation encompassed a large portion of the caudolateral S1, while the representation of the lower and upper lips occupied a large portion of the rostrolateral aspect of S1. We found that neuronal populations representing the perioral structures tended to have small receptive fields relative to other body part representations on the head and that the representation of the mystacial whiskers and perioral structures was coextensive with cytoarchitectonically defined barrel fields that extend from the caudolateral to a rostrolateral aspect of S1.

Conclusions: The relative magnification of the perioral representation in S1 reflects the importance of these regions for sensory-mediated behaviors such as tactile interactions in biparental care and social bonding. This highlights how environmental and behavioral factors shape S1 organization through brain-body synergy, suggesting that relatively small changes in experience can drive adaptive cortical plasticity that, over subsequent generations, drives the cortical phenotypic diversity across the rodent clade and mammals in general.

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Background: By examining species-specific innate behaviours, neuroethologists have characterized unique neural strategies and specializations from throughout the animal kingdom. Simultaneously, the field of evolutionary developmental biology (informally, "evo-devo") seeks to make inferences about animals' evolutionary histories through careful comparison of developmental processes between species, because evolution is the evolution of development. Yet despite the shared focus on cross-species comparisons, there is surprisingly little crosstalk between these two fields. Insights can be gleaned at the intersection of neuroethology and evo-devo. Every animal develops within an environment, wherein ecological pressures advantage some behaviours and disadvantage others. These pressures are reflected in the neurodevelopmental strategies employed by different animals across taxa.

Summary: Vision is a system of particular interest for studying the adaptation of animals to their environments. The visual system enables a wide variety of animals across the vertebrate lineage to interact with their environments, presenting a fantastic opportunity to examine how ecological pressures have shaped animals' behaviours and developmental strategies. Applying a neuroethological lens to the study of visual development, we advance a novel theory that accounts for the evolution of spontaneous retinal waves, an important phenomenon in the development of the visual system, across the vertebrate lineage.

Key messages: We synthesize literature on spontaneous retinal waves from across the vertebrate lineage. We find that ethological considerations explain some cross-species differences in the dynamics of retinal waves. In zebrafish, retinal waves may be more important for the development of the retina itself, rather than the retinofugal projections. We additionally suggest empirical tests to determine whether Xenopus laevis experiences retinal waves.

Introduction: Neural exaptations represent descent via transitions to novel neural functions. A primary transition in human cognitive and neural evolution was from a predominantly socially oriented primate brain to a brain that also instantiates and subserves science, technology, and engineering, all of which depend on mathematics. Upon what neural substrates and upon what evolved cognitive mechanisms did human capacities for science, technology, engineering, and mathematics (STEM), and especially its mathematical underpinnings, emerge? Previous theory focuses on roles for tools, language, and arithmetic in the cognitive origins of STEM, but none of these factors appears sufficient to support the transition.

Methods: In this article, I describe and evaluate a novel hypothesis for the neural origins and substrates of STEM-based cognition: that they are based in human kinship systems and human maximizing of inclusive fitness.

Results: The main evidence for this hypothesis is threefold. First, as demonstrated by anthropologists, human kinship systems exhibit complex mathematical and geometrical structures that function under sets of explicit rules, and such systems and rules pervade and organize all human cultures. Second, human kinship underlies the core algebraic mechanism of evolution, maximization of inclusive fitness, quantified as personal reproduction plus the sum of all effects on reproduction of others, each multiplied by their coefficient of relatedness to self. This is the only "natural" equation expected to be represented in the human brain. Third, functional imaging studies show that kinship-related cognition activates frontal-parietal regions that are also activated in STEM-related tasks. In turn, the decision-making that integrates kinship levels with costs and benefits from alternative behaviors has recently been shown to recruit the lateral septum, a hub region that combines internal (from the prefrontal cortex, amygdala, and other regions) and external information relevant to social behavior, using a dedicated subsystem of neurons specific to kinship.

Conclusions: Taken together, these lines of evidence suggest that kinship systems and kin-associated behaviors may represent exaptations for the origin of human STEM.

Introduction: Pythons are a well-studied model of postprandial physiological plasticity. Consuming a meal evokes a suite of physiological changes in pythons including one of the largest documented increases in post-feeding metabolic rates relative to resting values. However, little is known about how this plasticity manifests in the brain. Previous work has shown that cell proliferation in the python brain increases 6 days following meal consumption. This study aimed to confirm these findings and build on them in the long term by tracking the survival and maturation of these newly created cells across a 2-month period.

Methods: We investigated differences in neural cell proliferation in ball pythons 6 days after a meal with immunofluorescence using the cell-birth marker 5-bromo-12'-deoxyuridine (BrdU). We investigated differences in neural cell maturation in ball pythons 2 months after a meal using double immunofluorescence for BrdU and a reptilian ortholog of the neuronal marker Fox3.

Results: We did not find significantly greater rates of cell proliferation in snakes 6 days after feeding, but we did observe more new cells in neurogenic regions in fed snakes 2 months after the meal. Feeding was not associated with higher rates of neurogenesis, but snakes that received a meal had higher numbers of newly created nonneuronal cells than fasted controls. We documented particularly high cell survival rates in the olfactory bulbs and lateral cortex.

Conclusion: Consuming a meal stimulates cell proliferation in the brains of ball pythons after digestion is complete, although this effect emerged at a later time point in this study than expected. Higher rates of proliferation partially account for greater numbers of newly created non-neuronal cells in the brains of fed snakes 2 months after the meal, but our results also suggest that feeding may have a mild neuroprotective effect. We captured a slight trend toward higher cell survival rates in fed snakes, and survival rates were particularly high in brain regions associated with olfactory perception and processing. These findings shed light on the relationship between energy balance and the creation of new neural cells in the brains of ball pythons.

The comparative approach is a powerful way to explore the relationship between brain structure and cognitive function. Thus far, the field has been dominated by the assumption that a bigger brain somehow means better cognition. Correlations between differences in brain size or neuron number between species and differences in specific cognitive abilities exist, but these correlations are very noisy. Extreme differences exist between clades in the relationship between either brain size or neuron number and specific cognitive abilities. This means that correlations become weaker, not stronger, as the taxonomic diversity of sampled groups increases. Cognition is the outcome of neural networks. Here we propose that considering plausible neural network models will advance our understanding of the complex relationships between neuron number and different aspects of cognition. Computational modelling of networks suggests that adding pathways, or layers, or changing patterns of connectivity in a network can all have different specific consequences for cognition. Consequently, models of computational architecture can help us hypothesise how and why differences in neuron number might be related to differences in cognition. As methods in connectomics continue to improve and more structural information on animal brains becomes available, we are learning more about natural network structures in brains, and we can develop more biologically plausible models of cognitive architecture. Natural animal diversity then becomes a powerful resource to both test the assumptions of these models and explore hypotheses for how neural network structure and network size might delimit cognitive function.

Background: In the bestseller book "Why Zebras Don't Get Ulcers", Robert Sapolsky argues that animals do not suffer from stress-related diseases like humans because for them, stress is episodic, while humans in contrast suffer from chronic psychological stress. In particular, the idea that fish cannot experience psychological stress is still prevalent, partly due to the lack of a homologous brain area to the neocortex. However, emerging evidence suggests that teleosts can undergo psychological stress, defined as a subjective and perceptual experience of the stressor, and in recent years, the underlying mechanisms started to be unveiled.

Summary: The occurrence of cognitive appraisal in the assessment of stressors has been demonstrated in fish, indicating that the subjective evaluation of stimulus valence and salience, rather than absolute intrinsic characteristics of the stimulus itself, play a key role in the activation of the stress response. Moreover, individual biases (i.e., cognitive bias) in the cognitive appraisal of stimuli have also been described in fish, with some individuals consistently evaluating ambiguous stimuli as positive (aka optimists) whereas other individuals (aka pessimists) appraise them as negative. As a result, optimists and pessimists show consistent differences in stress reactivity and susceptibility/resilience to disease. Finally, social context has also been shown to modulate the response to aversive stimuli with the behavior of conspecifics either buffering or enhancing the response (i.e., social buffering vs. social contagion).

Key messages: Cognitive appraisal of stressors occurs in fish, implying that the stress response is modulated by a subjective and perceptual experience of the stressor. Moreover, interindividual consistent cognitive biases in the appraisal of stressors are also present in fish making some individuals more susceptible to stress-related diseases. Therefore, psychological stress has a health toll in fish, and psychologically stressed fish can potentially have ulcers.

Introduction: Transitions in temporal niche have occurred many times over the course of mammalian evolution. These are associated with changes in sensory stimuli available to animals, particularly with visual cues, because levels of light are so much higher during the day than at night. This relationship between temporal niche and available sensory stimuli elicits the expectation that evolutionary transitions between diurnal and nocturnal lifestyles will be accompanied by modifications of sensory systems that optimize the ability of animals to receive, process, and react to important stimuli in the environment.

Methods: This study examines the influence of temporal niche on investment in sensory brain tissue of 13 rodent species (five diurnal; eight nocturnal). Animals were euthanized and the brains immediately frozen on dry ice; olfactory bulbs were subsequently dissected and weighed, and the remaining brain was weighed, sectioned, and stained. Stereo Investigator was used to calculate volumes of four sensory regions that function in processing visual (lateral geniculate nucleus, superior colliculus) and auditory (medial geniculate nucleus, inferior colliculus) information. A phylogenetic framework was used to assess the influence of temporal niche on the relative sizes of these brain structures and of olfactory bulb weights.

Results: Compared to nocturnal species, diurnal species had larger visual regions, whereas nocturnal species had larger olfactory bulbs than their diurnal counterparts. Of the two auditory structures examined, one (medial geniculate nucleus) was larger in diurnal species, while the other (inferior colliculus) did not differ significantly with temporal niche.

Conclusion: Our results indicate a possible indirect association between temporal niche and auditory investment and suggest probable trade-offs of investment between olfactory and visual areas of the brain, with diurnal species investing more in processing visual information and nocturnal species investing more in processing olfactory information.