Nerve cells and animal behaviour Flashcards

Question

some behavioural patterns are stereotyped (fixed acts or fixed action patterns) can be triggered by specific stimuli (Tinbergen, 1952) research

Answer 1

Fero et al. (2011) Conte and Schulter (2013)

Answer 2

- Shortly after larval zebrafish become free swimming their behavior is modulated by both autochthonous signals and external stimuli. Larvae show rapid responses to a range of sensory cues but are also capable of executing extended behavioral programs in response to changes in the environment. At this early stage, larvae have a small repertoire of discrete stereotyped movements which are deployed in different contexts to generate appropriate behavior. We outline the range of behaviors defined in zebrafish larvae to date and discuss insights into neural function revealed by behavioral assays. A growing body of work demonstrates that tractability of behavior and neural connectivity in larval zebrafish facilitate the analysis of neural pathways underlying vertebrate motor control and sensory processing.

Answer 3

Mate choice by phenotype matching, whereby individuals prefer a mate whose phenotype is similar to their own, should facilitate speciation with gene flow. This is because the genes that control mate signal (the phenotype being matched) also determine the preferred mate signal (“mate preference”). Speciation is made even easier if phenotype matching is based on a trait under divergent natural selection. In this case, assortative mating should readily evolve as a byproduct of divergent selection on the trait. Previous observational studies of assortative mating between sympatric, hybridizing threespine stickleback species (Gasterosteus aculeatus complex) suggested that phenotype matching might occur by body size, a trait under divergent natural selection. To test this, we used experimental manipulation of body size to rule out the effects of confounding variables. We found that sizemanipulated benthic and limnetic stickleback females prefer mates whose body size more closely matches their own. It is thus likely that assortative mating by phenotype matching has facilitated the origin and persistence of benthic and limnetic threespine sticklebacks in the face of gene flow

Answer 4

- Pecks beak in order to be fed | - Cate - tested exposure and familiarisation - led to effect of red beak

Answer 5

D'Eath (1998) Bovet and Vauclair (2000) Soffie and Zayan (1977)

Answer 6

The use of video images in place of natural stimuli in animal behaviour experiments is reviewed. Unlike most other artificial means of stimulus presentation, video stimuli can depict complex moving objects such as other animals, preserving the temporal and spatial patterns of movement precisely as well as colour and sounds for repeated playback. Computer editing can give flexibility and control over all elements of the stimulus. A variety of limitations of video image presentation are also considered. Televisions and video monitors are designed with human vision in mind, and some non‐human animals that differ in aspects of visual processing such as their colour vision, critical flicker‐fusion threshold, perception of depth and visual acuity, may perceive video images differently to ourselves. The failure of video stimuli to interact with subjects can be a drawback for some studies. For video to be useful, it is important to confirm that the subject animal responds to the image in a comparable way to the real stimulus, and the criteria used to assess this are discussed. Finally, the contribution made by video studies to date in the understanding of animal visual responses is considered, and recommendations as to the future uses of video are made

Answer 7

The question of object–picture recognition has received relatively little attention in both human and comparative psychology; a paradoxical situation given the important use of image technology (e.g. slides, digitised pictures) made by neuroscientists in their experimental investigation of visual cognition. The present review examines the relevant literature pertaining to the question of the correspondence between and/or equivalence of real objects and their pictorial representations in animals and humans. Two classes of reactions towards pictures will be considered in turn: acquired responses in picture recognition experiments and spontaneous responses to pictures of biologically relevant objects (e.g. prey or conspecifics). Our survey will lead to the conclusion that humans show evidence of picture recognition from an early age; this recognition is, however, facilitated by prior exposure to pictures. This same exposure or training effect appears also to be necessary in nonhuman primates as well as in other mammals and in birds. Other factors are also identified as playing a role in the acquired responses to pictures: familiarity with and nature of the stimulus objects, presence of motion in the image, etc. Spontaneous and adapted reactions to pictures are a wide phenomenon present in different phyla including invertebrates but in most instances, this phenomenon is more likely to express confusion between objects and pictures than discrimination and active correspondence between the two. Finally, given the nature of a picture (e.g. bi-dimensionality, reduction of cues related to depth), it is suggested that object–picture recognition be envisioned in various levels, with true equivalence being a limited case, rarely observed in the behaviour of animals and even humans.

Answer 8

Two experiments (Exp.1, Exp.2) were carried out to investigate the effects of social releasers, i.e. models and calls of conspecifics, on the approach responses of Friesian-Dutch heifers. In Exp.1, models consisted of either a vague representation of a conspecific's shape, or of a life-sized photograph of a conspecific. Sound (S) stimulations (calls) and movement (M) were combined to these visual (V) models. In Exp.2, V models and S stimulations were presented either separately or in combination. Models consisted of a ♂ and of a ♀ life-sized photograph and S stimulations consisted of recorded calls of ♂♂ or of ♀♀ conspecifics. In Exp.1, a significant increase in responsiveness was found after addition of sound S to the V models, especially to the photographs. Adding S to V models resulted in a much higher increase in responsiveness than adding M to V models. An additive effect was also found in Exp.2: combined presentations of V and S increased significantly the number of responses and of responding subjects as compared to either V or S separate presentations. In both Exp.1 and Exp.2, the total number of responses was a little more than twice as high for combined presentation of V and S as it was for V separate presentations, or for S separate presentations (Exp.2). In Exp.2, a complete verification of Seitz's law of heterogeneous summation of the stimuli was attempted by a further comparison, demonstrating that the releasing effect of V and S presented in combination (simultaneously) was equivalent to the number of responses found after addition of the partial effects of V and S presented separately (successively).

Answer 9

Land and Layne (1995) Horch (1971) Kobayashi and Archdale (2020)

Answer 10

Male fiddler crabs (Uca pugilator Bosc) have visual control systems that enable them to track other crabs in front or behind, and to keep potential predators to the side, where escape is easiest. The system for tracking conspecifics appears to be double, with a lowgain velocity-sensitive mechanism operating over about a 90 ~ range, backed up by a position-sensitive mechanism at the ends of this range which is responsible for recentring the target. This system has separate front and rear ranges, with a gap in the direction of the claw. The crabs separately fixate the burrow entrance, keeping it in the direction opposite the claw. Predator evasion employs two systems simultaneously. An openloop mechanism directs the crab's translatory movements directly away from the stimulus, and a rotational mechanism using continuous feedback turns the crab so that the stimulus is kept at near 90 ~ to the body axis. Both systems are sensitive to the angular position of the stimulus, not its velocity. Eye movements have little or no role in object tracking. An attempt is made to list Uca's known visual control systems.

Answer 11

Male fiddler crabs (Uca pugilator Bosc) have visual control systems that enable them to track other crabs in front or behind, and to keep potential predators to the side, where escape is easiest. The system for tracking conspecifics appears to be double, with a lowgain velocity-sensitive mechanism operating over about a 90 ~ range, backed up by a position-sensitive mechanism at the ends of this range which is responsible for recentring the target. This system has separate front and rear ranges, with a gap in the direction of the claw. The crabs separately fixate the burrow entrance, keeping it in the direction opposite the claw. Predator evasion employs two systems simultaneously. An openloop mechanism directs the crab's translatory movements directly away from the stimulus, and a rotational mechanism using continuous feedback turns the crab so that the stimulus is kept at near 90 ~ to the body axis. Both systems are sensitive to the angular position of the stimulus, not its velocity. Eye movements have little or no role in object tracking. An attempt is made to list Uca's known visual control systems.

Answer 12

Mating strategy and sexual dimorphism of morphological traits of the leucosiid crab Pyrhila pisum were elucidated by analysing relative growth patterns of chelipeds and abdomen, and gonad development patterns. Male adults had long chelipeds compared with juvenile males and females. Among male adults, two phases with different slopes could be found in the regression lines; their chelipeds growth pattern changed from negative allometry to positive and longer chelipeds developed in large adults. The growth is more markedly expressed in the merus than in the propodus. Female adults had wider abdominal segments and a thicker body compared with juvenile females and males. Abdomen of females was greatly enlarged by a puberty moult. Male adults had well-developed gonads similar to female adults, and the weights of male gonads were often larger than those of females of the same body size. For adult males, a negative correlation was detected between carapace width and the weight ratio of their gonads, but no significant relationship was detected for adult females. Females had large and well-bloated seminal receptacles, whose weight was nearly equal to gonad weight. There was little difference in the amount of seminal receptacles regardless of the body size of females. There is a trade-off relationship in the development between chelipeds and gonads in adult males. Probably young adult males compensate for the disadvantageous condition of guarding by increasing the number of spermatozoids, and old adult males invest more of their energy to their chelae for guarding while decreasing investment in sperm production.

Answer 13

- Study of localisation and release of such stereotyped and elementary forms of behaviour in the CNS (e.g. von Holst, 1939) - J. Segaar (1961) studied the effect of brain lesions on fixed motor behaviour in the three-spined stickleback - Co-emergent with neuroscience

Answer 14

Bressler and Kelso (2001) Key (2016)

Answer 15

- The cerebral cortex makes a critical contribution to cognition by performing integrative functions that combine and reconcile information from a multitude of sources. The cortex integrates information from different sensory modalities; sensory information with internally generated information representing goals, plans, memories and emotions; and information of all these types with motor information for the initiation and production of specific actions. In addition, the cortex performs important segregative functions by allocating a diversity of tasks to different areas and regions. Considering that a person's environment can change rapidly and unpredictably, the cortex must be able to maintain currency with that environment by preserving a balance between integrative and segregative functions on a sub-second time scale. We have shown in this review how the cortical system manifests metastability through the organization of large-scale coordinated networks, in which the constituent areas become interdependent without losing their independence. The metastable dynamics of relative coordination endow cognitive functions with the capacity for rapid and fluid change, without ever relaxing into stable states. - This change is highly adaptable: people and animals can repeatedly modify their cognitive processes to produce a course of action that successfully accommodates a variety of time-varying conditions. We have shown how the transient, conjoint coordination of groups of distributed cortical areas comprising large-scale networks can allow individual local-area spatial activity distributions to converge to informationally consistent patterns, thereby satisfying global computational demands. This computational strategy is extremely flexible, allowing each participating local area to act as a unique information source for the large-scale network, and different combinations of areas to combine their information in real time. The context for information processing in each area of the large-scale network is dynamically created by virtue of the combined constraints imposed on it. The result is an enormous computational advantage for perceptual[50](https://www.sciencedirect.com/science/article/pii/S1364661300015643#BIB50) and motor[57](https://www.sciencedirect.com/science/article/pii/S1364661300015643#BIB57) operations. Through the relative coordination of cortical areas, governed by metastable coordination dynamics, these processes are effectively combined with others into coherent, global functions that provide a unity of cognition.

Answer 16

The vertebrate brain is hierarchically assembled about orthogonal axes using organizing centers that control cascades of signaling events. The reiterative generation of these centers at defined times, and in precise spatial locations, leads to the conversion of a contiguous and homogenous epithelial sheet into the most complex biological tissue in the animal kingdom. The critical events orchestrating the construction of a “typical” vertebrate brain are described. Attention is focused on specification of major brain regions common across the vertebrate phylogeny, rather than on the differentiation of constituent cell types and specific cytoarchitectures. By uncloaking the complex spatial interactions that unfold temporally during the build of the vertebrate brain, it becomes clear why regeneration of this tissue following injury is such a challenging task. And yet, while mammalian brains fail to regenerate, the brains of non-mammalian vertebrates, such as teleosts, reptiles and amphibians, can successfully reconstitute brain tissue following traumatic injury. Understanding the molecular and cellular bases of this remarkable regenerative capacity is revealing the importance of developmental programs, as well as exposing unexpected roles for extraneous processes such as inflammation. Recent discoveries are now fuelling hope for future therapeutic approaches that will ameliorate the debilitating consequences of brain injury in humans.

Answer 17

The vertebrate brain is hierarchically assembled about orthogonal axes using organizing centers that control cascades of signaling events. The reiterative generation of these centers at defined times, and in precise spatial locations, leads to the conversion of a contiguous and homogenous epithelial sheet into the most complex biological tissue in the animal kingdom. The critical events orchestrating the construction of a “typical” vertebrate brain are described. Attention is focused on specification of major brain regions common across the vertebrate phylogeny, rather than on the differentiation of constituent cell types and specific cytoarchitectures. By uncloaking the complex spatial interactions that unfold temporally during the build of the vertebrate brain, it becomes clear why regeneration of this tissue following injury is such a challenging task. And yet, while mammalian brains fail to regenerate, the brains of non-mammalian vertebrates, such as teleosts, reptiles and amphibians, can successfully reconstitute brain tissue following traumatic injury. Understanding the molecular and cellular bases of this remarkable regenerative capacity is revealing the importance of developmental programs, as well as exposing unexpected roles for extraneous processes such as inflammation. Recent discoveries are now fuelling hope for future therapeutic approaches that will ameliorate the debilitating consequences of brain injury in humans.

Answer 18

- Hodgkin-Huxley model of the action potential (1952) | - Nobel price in 1963

Answer 19

Yalkinkaya et al. (2019) Mathur et al. (2018)

Answer 20

Thermodynamic analyses are performed to determine the effects of global warming on information transmittance in the squid giant axon. Squids are cold-blooded animals and their body temperature is the same as that of the environment. Modelling showed that at 6.3 degrees C energy cost, exergy destruction and entropy generation were 1.77 x 10(-10) kJ/cm(2), 3.49 x 10(-9) kJ/cm(2), and 1.25 x 10(-11) kJ/K cm(2), respectively. Entropy generation decreased with temperature increase, implying that living became easier for the squid. Thermodynamic analyses performed in this study may help to explain why the squid populations thrive with global warming.

Answer 21

Local translation of membrane proteins in neuronal subcellular domains like soma, dendrites and axon termini is well-documented. In this study, we isolated the electrical signaling unit of an axon by dissecting giant axons from mature squids (Dosidicus gigas). Axoplasm extracted from these axons was found to contain ribosomal RNAs, similar to 8000 messenger RNA species, many encoding the translation machinery, membrane proteins, translocon and signal recognition particle (SRP) subunits, endomembrane-associated proteins, and unprecedented proportions of SRP RNA (similar to 68% identical to human homolog). While these components support endoplasmic reticulum-dependent protein synthesis, functional assessment of a newly synthesized membrane protein in axolemma of an isolated axon is technically challenging. Ion channels are ideal proteins for this purpose because their functional dynamics can be directly evaluated by applying voltage clamp across the axon membrane. We delivered in vitro transcribed RNA encoding native or Drosophila voltage-activated Shaker K-V channel into excised squid giant axons. We found that total K+ currents increased in both cases; with added inactivation kinetics on those axons injected with RNA encoding the Shaker channel. These results provide unambiguous evidence that isolated axons can exhibit de novo synthesis, assembly and membrane incorporation of fully functional oligomeric membrane proteins.

Answer 22

- Early, ethological concepts of mechanisms underlying behavioural patterns - Neurobiology unravelling the substrates for behaviour and plasticity - Research in diff species and considering evolution and ecology

Answer 23

Krakauer et al. (2017) Brown and Bivort (2018)

Answer 24

There are ever more compelling tools available for neuroscience research, ranging from selective genetic targeting to optogenetic circuit control to mapping whole connectomes. These approaches are coupled with a deep-seated, often tacit, belief in the reductionist program for understanding the link between the brain and behavior. The aim of this program is causal explanation through neural manipulations that allow testing of necessity and sufficiency claims. We argue, however, that another equally important approach seeks an alternative form of understanding through careful theoretical and experimental decomposition of behavior. Specifically, the detailed analysis of tasks and of the behavior they elicit is best suited for discovering component processes and their underlying algorithms. In most cases, we argue that study of the neural implementation of behavior is best investigated after such behavioral work. Thus, we advocate a more pluralistic notion of neuroscience when it comes to the brain-behavior relationship: behavioral work provides understanding, whereas neural interventions test causality.

Answer 25

There are ever more compelling tools available for neuroscience research, ranging from selective genetic targeting to optogenetic circuit control to mapping whole connectomes. These approaches are coupled with a deep-seated, often tacit, belief in the reductionist program for understanding the link between the brain and behavior. The aim of this program is causal explanation through neural manipulations that allow testing of necessity and sufficiency claims. We argue, however, that another equally important approach seeks an alternative form of understanding through careful theoretical and experimental decomposition of behavior. Specifically, the detailed analysis of tasks and of the behavior they elicit is best suited for discovering component processes and their underlying algorithms. In most cases, we argue that study of the neural implementation of behavior is best investigated after such behavioral work. Thus, we advocate a more pluralistic notion of neuroscience when it comes to the brain-behavior relationship: behavioral work provides understanding, whereas neural interventions test causality.

Answer 26

- „Neuroethogists believe that we can learn a great deal of general principles about nervous systems by studying systems that are specialized. Neuroethogists learn from animals that experience a different sensory world from our own. These and other questions derive this introductory survey of neuroethology, including exotic senses, amazing motor programs, and surprising integration.” Carl D. Hopkins (Cornell University, Department of Neurobiology and Behavior) - „Drosophila offers a facile and economical whole animal system with many homologous organs to humans, high functional conservation and established methods of generating and validating human disease models. Nevertheless, it remains relatively underused as a drug discovery tool probably because its relevance to mammalian systems remains under question. However, recent exciting success stories using Drosophila disease models for drug screening, repositioning and validation strongly suggest that fly models should figure prominently in the drug discovery pipeline from bench to bedside.“ Katerina Papanikolopoulou et al. (2019). Expert Opinion on Drug discovery, 14(3), 303-313.

Answer 27

- Machine vision algorithms allow to track the fly, monitor the posture of the body and wings. High-throughput behavioural screening facilitates the study of the role of genes in social behaviour in fruitflies (aggression and courtship).

Answer 28

Branson et al. (2009) Dell et al. (2014)

Answer 29

We present a camera-based method for automatically quantifying the individual and social behaviors of fruit flies, Drosophila melanogaster, interacting in a planar arena. Our system includes machine-vision algorithms that accurately track many individuals without swapping identities and classification algorithms that detect behaviors. The data may be represented as an ethogram that plots the time course of behaviors exhibited by each fly or as a vector that concisely captures the statistical properties of all behaviors displayed in a given period. We found that behavioral differences between individuals were consistent over time and were sufficient to accurately predict gender and genotype. In addition, we found that the relative positions of flies during social interactions vary according to gender, genotype and social environment. We expect that our software, which permits high-throughput screening, will complement existing molecular methods available in Drosophila, facilitating new investigations into the genetic and cellular basis of behavior.

Answer 30

We present a camera-based method for automatically quantifying the individual and social behaviors of fruit flies, Drosophila melanogaster, interacting in a planar arena. Our system includes machine-vision algorithms that accurately track many individuals without swapping identities and classification algorithms that detect behaviors. The data may be represented as an ethogram that plots the time course of behaviors exhibited by each fly or as a vector that concisely captures the statistical properties of all behaviors displayed in a given period. We found that behavioral differences between individuals were consistent over time and were sufficient to accurately predict gender and genotype. In addition, we found that the relative positions of flies during social interactions vary according to gender, genotype and social environment. We expect that our software, which permits high-throughput screening, will complement existing molecular methods available in Drosophila, facilitating new investigations into the genetic and cellular basis of behavior.

Answer 31

- Reflex responses can be very fast | - May not require communication with the brain – not every pathway is routed through the brain

Answer 32

Morris and Lattanzio (2020) Leffler et al. (2020)

Answer 33

- Optimal escape theory has proven useful for understanding the dynamics of antipredator behaviour in animals; however, approaches are often limited to single-population studies. We studied how the escape behaviour of tree lizards (Urosaurus ornatus) varied across a disturbance gradient. We also considered how sex, body temperature, and perch temperature affected their escape decisions. Both sexes exhibited similar response patterns; however, lizards in the most-disturbed habitat, as well as cooler (body or perch temperature) lizards, initiated escape earlier (but did not flee further) than other animals. Increased wariness as indicated by earlier escape suggests that frequently-disturbed, more-open localities may be stressful habitats for species like U. ornatus. In addition, because cooler temperatures limit locomotor performance capacity, escape decisions should also depend on a species' thermal ecology. Overall, we stress the importance of multi-population approaches for capturing the variety of ways species adaptively respond to the threat of predation across habitat gradients.

Answer 34

- Optimal escape theory has proven useful for understanding the dynamics of antipredator behaviour in animals; however, approaches are often limited to single-population studies. We studied how the escape behaviour of tree lizards (Urosaurus ornatus) varied across a disturbance gradient. We also considered how sex, body temperature, and perch temperature affected their escape decisions. Both sexes exhibited similar response patterns; however, lizards in the most-disturbed habitat, as well as cooler (body or perch temperature) lizards, initiated escape earlier (but did not flee further) than other animals. Increased wariness as indicated by earlier escape suggests that frequently-disturbed, more-open localities may be stressful habitats for species like U. ornatus. In addition, because cooler temperatures limit locomotor performance capacity, escape decisions should also depend on a species' thermal ecology. Overall, we stress the importance of multi-population approaches for capturing the variety of ways species adaptively respond to the threat of predation across habitat gradients.

Answer 35

- Neurons and their interactions are very similar across the animal kingdom, what differs is the number of cells, complexity of connectivity and structure of the nervous system - All animals the same at the neural level– all neurons look the same

Answer 36

Paulin and Cahill-Lane (2019) Sousa et al. (2017)

Answer 37

- Neurons and their interactions are very similar across the animal kingdom, what differs is the number of cells, complexity of connectivity and structure of the nervous system - All animals the same at the neural level– all neurons look the same

Answer 38

- Multiple lines of evidence show that key aspects of human brain organization and development scale as expected, while cognition does not. Even though the way our brain is built is not exceptional, we differ by a unique combination of mental abilities, combined with higher general intelligence. While higher general intelligence compared to NHPs may likely be the product of increased relative and absolute neuron number, especially in the neocortex, our superiority in specific cognitive abilities is likely the result of mosaic structural rewiring and molecular reorganization of specific neural circuits and cell types. These observations, as well as the study of brain size and organization in extinct primates (Falk, 2014; Neubauer, 2014; Pearce et al., 2013; Wood and Baker, 2011; Zollikofer and De Leo´ n, 2013), suggest that many independent changes rather than one single defining event have occurred across the nervous system in the human lineage. It is also likely that these changes have affected many, if not all, brain structures and levels of organization. - Advancements in high-throughput molecular biology and biochemistry technologies have enabled unprecedented identification of human-specific features that may contribute to unique aspects of human brain development. For example, several recent studies have mapped gene expression to specific cell types during brain development, using various single-cell sequencing approaches (Johnson et al., 2015; Lui et al., 2014; Onorati et al., 2016; Pollen et al., 2015). The cellular-level resolution of differential expression possible through these approaches, both among neural progenitor cells and subsequent postmitotic populations, allows a better understanding of the myriad fine-tuned processes governing early brain development. High-throughput techniques also permit, to some degree, the systematization of key aspects of the functional characterization of human specific genomic elements. This is the case for the massively parallel reporter assays, which enable simultaneous testing of the regulatory activity of hundreds of thousands of putative regulatory elements (Shlyueva et al., 2014). Continued efforts are both important and critical in many areas, including characterizing the extent of human diversity, expanding highquality annotations of NHP genomes, and increasing the coverage of gene expression profiles across more tissues and time points. Therefore, within the context of human CNS development and evolution, it will be valuable to profile transcriptional dynamics in developmental NHP samples from an extended number of CNS regions. Most of the recent efforts have focused on a few regions of the forebrain and cerebellum, while almost no data are available on the majority of other regions of the human or NHP CNS.

Answer 39

How to investigate: 1. comparative neuroanatomy - study brain structures and neuronal connectivity in different species of selected groups (taxon/taxa) within a phylogenetic lineage 1. behavioural physiology, neuroethology - measure neural activity and link to behavioural responses with consideration of different tasks and species-specific adaptations 2. neurogenetics - identify neurons and brain areas from different pattersn of gene activity and link these to different tasks and behavioural responses

Answer 40

- **Concerted brain evolution:** size-associated variations (or allometric effects) within a phylogenetic lineage (e.g. enlargement of the whole brain) - increase in body size often also includes increase in brain size - Small body = impossible physically to carry larger brains - Bigger animals can have big or small brains - Maintenance of brain is very costly - Bigger brain = process more information - Northcutt (2002)

Answer 41

Moore and DeVoogd (2017) Herculano-Houzel et al. (2014)

Answer 42

Vertebrate brains differ in overall size, composition and functional capacities, but the evolutionary processes linking these traits are unclear. Two leading models offer opposing views: the concerted model ascribes major dimensions of covariation in brain structures to developmental events, whereas the mosaic model relates divergent structures to functional capabilities. The models are often cast as incompatible, but they must be unified to explain how adaptive changes in brain structure arise from pre-existing architectures and developmental mechanisms. Here we show that variation in the sizes of discrete neural systems in songbirds, a species-rich group exhibiting diverse behavioural and ecological specializations, supports major elements of both models. In accordance with the concerted model, most variation in nucleus volumes is shared across functional domains and allometry is related to developmental sequence. Per the mosaic model, residual variation in nucleus volumes is correlated within functional systems and predicts specific behavioural capabilities. These comparisons indicate that oscine brains evolved primarily as a coordinated whole but also experienced significant, independent modifications to dedicated systems from specific selection pressures. Finally, patterns of covariation between species and brain areas hint at underlying developmental mechanisms.

Answer 43

Vertebrate brains differ in overall size, composition and functional capacities, but the evolutionary processes linking these traits are unclear. Two leading models offer opposing views: the concerted model ascribes major dimensions of covariation in brain structures to developmental events, whereas the mosaic model relates divergent structures to functional capabilities. The models are often cast as incompatible, but they must be unified to explain how adaptive changes in brain structure arise from pre-existing architectures and developmental mechanisms. Here we show that variation in the sizes of discrete neural systems in songbirds, a species-rich group exhibiting diverse behavioural and ecological specializations, supports major elements of both models. In accordance with the concerted model, most variation in nucleus volumes is shared across functional domains and allometry is related to developmental sequence. Per the mosaic model, residual variation in nucleus volumes is correlated within functional systems and predicts specific behavioural capabilities. These comparisons indicate that oscine brains evolved primarily as a coordinated whole but also experienced significant, independent modifications to dedicated systems from specific selection pressures. Finally, patterns of covariation between species and brain areas hint at underlying developmental mechanisms.

Answer 44

- Human and primate brains have very large neocortex, with more areas and unique connectivities than other mammals - Associated with larger number of non-primary cortical areas - Other areas, e.g. subcortical such as dorsal thalamus do not change much in size - Enlargement of frontal brain including of thalamus has occurred independently in various vertebrate groups - drives certain characteristics of cog and behavioural performance - Increase in selective brain components - Halley and Krubitzer (2019)

Answer 45

DiCasien and Higham (2019) O'Donnell et al. (2018) Butler (2008) Branco and Regrave (2020)

Answer 46

The mammalian brain is composed of numerous functionally distinct structures that vary in size within and between clades, reflecting selection for sensory and cognitive specialization. Primates represent a particularly interesting case in which to examine mosaic brain evolution since they exhibit marked behavioural variation, spanning most social structures, diets and activity periods observed across mammals. Although studies have consistently demonstrated a trade-off between visual and olfactory specialization in primates, studies of some regions (for example, the neocortex) have produced conflicting results. Here, we analyse the socioecological factors influencing the relative size of 33 brain regions, using updated statistical techniques and data from more species and individuals than previous studies. Our results confirm that group-living species and those with high-quality diets have expanded olfactory or visual systems, depending on whether they are nocturnal or diurnal. Conversely, regions associated with spatial memory are expanded in solitary species and those with low-quality diets, suggesting a trade-off between visual processing and spatial memory. Contrary to previous work, we show that diet quality predicts relative neocortex size at least as well as, if not better than, social complexity. Overall, our results demonstrate that primate brain structure is largely driven by selection on sensory and cognitive specializations that develop in response to divergent socioecological niches.

Answer 47

The mammalian brain is composed of numerous functionally distinct structures that vary in size within and between clades, reflecting selection for sensory and cognitive specialization. Primates represent a particularly interesting case in which to examine mosaic brain evolution since they exhibit marked behavioural variation, spanning most social structures, diets and activity periods observed across mammals. Although studies have consistently demonstrated a trade-off between visual and olfactory specialization in primates, studies of some regions (for example, the neocortex) have produced conflicting results. Here, we analyse the socioecological factors influencing the relative size of 33 brain regions, using updated statistical techniques and data from more species and individuals than previous studies. Our results confirm that group-living species and those with high-quality diets have expanded olfactory or visual systems, depending on whether they are nocturnal or diurnal. Conversely, regions associated with spatial memory are expanded in solitary species and those with low-quality diets, suggesting a trade-off between visual processing and spatial memory. Contrary to previous work, we show that diet quality predicts relative neocortex size at least as well as, if not better than, social complexity. Overall, our results demonstrate that primate brain structure is largely driven by selection on sensory and cognitive specializations that develop in response to divergent socioecological niches.

Answer 48

Enlargement of the forebrain, including elaboration of the thalamus, has occurred independently within different groups of vertebrates. Dorsal and ventral thalamic territories can be identified in most vertebrates, with variations in the presence of GABAergic neuronal components. An inhibitory thalamic reticular nucleus-like input to the dorsal thalamus might be a common feature, as might the organizational plan of two divisions of the dorsal thalamus, the lemnothalamus and collothalamus. Differential, independent elaboration of these divisions occurred in mammals and sauropsids (reptiles and birds), making their evolutionary relationships challenging to discern. Not all of the crucial features identified for mammalian thalamocortical circuitry are present in other vertebrates, but birds share the most features identified to date. These include specific and nonspecific thalamic relay neurons, reciprocal pallial projections, and a GABAergic thalamic reticular nucleus with some but not all hodological features. Because birds share many higher-level cognitive abilities and, thus, possibly higher-level consciousness, with mammals, comparison of the thalamocortical (thalamopallial) circuitry might prove a fruitful resource for testing functional hypotheses. Comparisons with selected other vertebrates that likewise have relatively large brain:body ratios and also exhibit some cognitively sophisticated behaviors, such as cichlid fish, might also prove valuable.

Answer 49

Escape is one of the most studied animal behaviors, and there is a rich normative theory that links threat properties to evasive actions and their timing. The behavioral principles of escape are evolutionarily conserved and rely on elementary computational steps such as classifying sensory stimuli and executing appropriate movements. These are common building blocks of general adaptive behaviors. Here we consider the computational challenges required for escape behaviors to be implemented, discuss possible algorithmic solutions, and review some of the underlying neural circuits and mechanisms. We outline shared neural principles that can be implemented by evolutionarily ancient neural systems to generate escape behavior, to which cortical encephalization has been added to allow for increased sophistication and flexibility in responding to threat.

Answer 50

- Only largest rodent, the capybara, has similar dorsal thalamus-to-neocortex as the smallest primate - Halley and Krubitzer (2019)

Answer 51

Willemet (2019) Plinio and Ebisch (2020) Halley et al. (2020)

Answer 52

The idea that allometry in the context of brain evolution mainly result from constraints channelling the scaling of brain components is deeply embedded in the field of comparative neurobiology. Constraints, however, only prevent or limit changes, and cannot explain why these changes happen in the first place. In fact, considering allometry as a lack of change may be one of the reasons why, after more than a century of research, there is still no satisfactory explanatory framework for the understanding of species differences in brain size and composition in mammals. The present paper attempts to tackle this issue by adopting an adaptationist approach to examine the factors behind the evolution of brain components. In particular, the model presented here aims to explain the presence of patterns of covariation among brain components found within major taxa, and the differences between taxa. The key determinant of these patterns of covariation within a taxon-cerebrotype (groups of species whose brains present a number of similarities at the physiological and anatomical levels) seems to be the presence of taxon-specific patterns of selection pressures targeting the functional and structural properties of neural components or systems. Species within a taxon share most of the selection pressures, but their levels scale with a number of factors that are often related to body size. The size and composition of neural systems respond to these selection pressures via a number of evolutionary scenarios, which are discussed here. Adaptation, rather than, as generally assumed, developmental or functional constraints, thus appears to be the main factor behind the allometric scaling of brain components. The fact that the selection pressures acting on the size of brain components form a pattern that is specific to each taxon accounts for the peculiar relationship between body size, brain size and composition, and behavioural capabilities characterizing each taxon. While it is important to avoid repeating the errors of the “Panglossian paradigm”, the elements presented here suggests that an adaptationist approach may shed a new light on the factors underlying, and the functional consequences of, species differences in brain size and composition.

Answer 53

The study of the evolution of brain–behaviour relationships concerns understanding the causes and repercussions of cross‐ and within‐species variability. Understanding such variability is a main objective of evolutionary and cognitive neuroscience, and it may help explaining the appearance of psychopathological phenotypes. Although brain evolution is related to the progressive action of selection and adaptation through multiple paths (e.g. mosaic vs. concerted evolution, metabolic vs. structural and functional constraints), a coherent, integrative framework is needed to combine evolutionary paths and neuroscientific evidence. Here, we review the literature on evolutionary pressures focusing on structural–functional changes and developmental constraints. Taking advantage of recent progress in neuroimaging and cognitive neuroscience, we propose a twofold hypothetical model of brain evolution. Within this model, global and local trajectories imply rearrangements of neural subunits and subsystems and of behavioural repertoires of a species, respectively. We incorporate these two processes in a game in which the global trajectory shapes the structural–functional neural substrates (i.e. players), while the local trajectory shapes the behavioural repertoires (i.e. stochastic payoffs).

Answer 54

Which areas of the neocortex are involved in the control of movement, and how is motor cortex organized across species? Recent studies using long-train intracortical microstimulation demonstrate that in addition to M1, movements can be elicited from somatosensory regions in multiple species. In the rat, M1 hindlimb and forelimb movement representations have long been thought to overlap with somatosensory representations of the hindlimb and forelimb in S1, forming a partial sensorimotor amalgam. Here we use long-train intracortical microstimulation to characterize the movements elicited across frontal and parietal cortex. We found that movements of the hindlimb, forelimb, and face can be elicited from both M1 and histologically defined S1 and that representations of limb movement types are different in these two areas. Stimulation of S1 generates retraction of the contralateral forelimb, while stimulation of M1 evokes forelimb elevation movements that are often bilateral, including a rostral region of digit grasping. Hindlimb movement representations include distinct regions of hip flexion and hindlimb retraction evoked from S1 and hip extension evoked from M1. Our data indicate that both S1 and M1 are involved in the generation of movement types exhibited during natural behavior. We draw on these results to reconsider how sensorimotor cortex evolved.

Answer 55

- We can measure neuronal signals as difference in potential on each size of the membrane (units - Volt) by creating an electrical circuit with wired electrodes that are inserted **inside (intracellular fluid)** and **outside (extracellular fluid)** the neuron

Answer 56

We can measure neuronal signals as difference in potential on each size of the membrane (units - Volt) by creating an electrical circuit with wired electrodes that are placed close outside the neuron (extracellular fluid) relative to other tissues elsewhere (extracellular fluid)

Answer 57

- Placing electrodes in tissues or dissociated cells: - intracellular recordings of membrane potentials - extracellular recordings of membrane potentials (single-and multi-unit recordings, EMG) - Placing electrodes on skin/scalp: - extracellular recordings of membrane potentials (EEG, EMG) - Optical methods to measure neural activity, e.g. optical imaging (Ca2+-imaging, fMRI, MRI, PET) measuring activation of processes that are correlated with changes in membrane potential in neurons

Answer 58

1. Extracellular recording of multiple unites 2. Intracellular recording from a single motoneuron 3. Extracellular recording of multiple units from nerve tract (bundle of axons) with hook electrodes 4. Intracellular recordings from muscle fibre 5. EMG - Further away = more noisy - Carew (2000)

Answer 59

- Fru m - allele of Fru expressed in males - Fru f - allele of Fru expressed in females - Removal of gene = don't show sex specific behaviours - Bontonou and Thomas (2014)

Answer 60

Revadi et al. (2015) Jezovit et al. (2017) Martel et al. (2016)

Answer 61

A high reproductive potential is one reason for the rapid spread of Drosophila suzukii in Europe and in the United States. In order to identify mechanisms that mediate mating and reproduction in D. suzukii we studied the fly’s reproductive behavior, diurnal mating activity and sexual maturation. Furthermore, we studied the change of female cuticular hydrocarbons (CHCs) with age and conducted a preliminary investigation on the role of female-derived chemical signals in male mating behavior. Sexual behavior in D. suzukii is characterized by distinct elements of male courtship leading to female acceptance for mating. Time of day and age modulate D. suzukii mating activity. As with other drosophilids, female sexual maturity is paralleled by a quantitative increase in CHCs. Neither female CHCs nor other olfactory signals were required to induce male courtship, however, presence of those signals significantly increased male sexual behavior. With this pilot study we hope to stimulate research on the reproductive biology of D. suzukii, which is relevant for the development of pest management tools.

Answer 62

Social behaviour emerges from the local environment but is constrained by the animal's life history and its evolutionary lineage. In this perspective, we consider the genus Drosophila and provide an overview of how these constraints can shape how individuals interact. Our focus is restricted to visual and chemical signals and how their use varies across species during courtship – currently the only social behaviour well-studied across many Drosophila species. We broadly categorize species into four climatic groups – cosmopolitan, tropical, temperate and arid – which serve as discussion points as we review comparative behavioural and physiological studies and relate them to the abiotic conditions of a species environment. We discuss how the physiological and behavioural differences among many fly species may reflect life history differences as much as, or even more than, differences in phylogeny. This perspective serves not only to summarize what has been studied across drosophilids, but also to identify questions and outline gaps in the literature worth pursuing for progressing the understanding of behavioural evolution in Drosophila.

Answer 63

Several neotropical orchid genera have been proposed as being sexually deceptive; however, this has been carefully tested in only a few cases. The genus Telipogon has long been assumed to be pollinated by male tachinid flies during pseudocopulatory events but no detailed confirmatory reports are available. Here, we have used an array of methods to elucidate the pollination mechanism in Telipogon peruvianus. The species presents flowers that have a mean floral longevity of 33 days and that are self-compatible, although spontaneous self-pollination does not occur. The flowers attract males of four tachinid species but only the males of an undescribed Eudejeania (Eudejeania aff. browni; Tachinidae) species are specific pollinators. Males visit the flowers during the first few hours of the day and the pollination success is very high (42% in one patch) compared with other sexually deceptive species. Female-seeking males are attracted to the flowers but do not attempt copulation with the flowers, as is usually described in sexually deceptive species. Nevertheless, morphological analysis and behavioural tests have shown an imperfect mimicry between flowers and females suggesting that the attractant stimulus is not based only on visual cues, as long thought. Challenging previous conclusions, our chemical analysis has confirmed that flowers of Telipogon release volatile compounds; however, the role of these volatiles in pollinator behaviour remains to be established. Pollinator behaviour and histological analyses indicate that Telipogon flowers possess scent-producing structures throughout the corolla. Our study provides the first confirmed case of (i) a sexually deceptive species in the Onciidinae, (ii) pollination by pre-copulatory behaviour and (iii) pollination by sexual deception involving tachinid flies.

Answer 64

- Manipulations of the neural circuits underlying courtship behaviour - knock-out or inhib of genes in neurons - permanently or reversibly (can be done by changing temperature in some species) - generating and testing gynandromorphs (for example a fly with mixtures of male and female brain tissues) - knock-down or reversibly silence neurons in normally-behaving transgenic flies (e.g. change in ambient temp, illuminating with UV-light) - Fru (fruitless) gene is only expressed in neurons - It codes 4 proteins that are regulatory genes (which control other genes)

Answer 65

Stockinger et al. (2005) Yu et al. (2010)

Answer 66

Male-specific fruitless (fru) products (FruM) are both necessary and sufficient to “hardwire” the potential for male courtship behavior into the Drosophila nervous system. FruM is expressed in ∼2% of neurons in the male nervous system, but not in the female. We have targeted the insertion of GAL4 into the fru locus, allowing us to visualize and manipulate the FruM-expressing neurons in the male as well as their counterparts in the female. We present evidence that these neurons are directly and specifically involved in male courtship behavior and that at least some of them are interconnected in a circuit. This circuit includes olfactory neurons required for the behavioral response to sex pheromones. Anatomical differences in this circuit that might account for the dramatic differences in male and female sexual behavior are not apparent.

Answer 67

- Background - Courtship behavior in *Drosophila* has been causally linked to the activity of the heterogeneous set of ∼1500 neurons that express the sex-specific transcripts of the *fruitless* (*fru*) gene, but we currently lack an appreciation of the cellular diversity within this population, the extent to which these cells are sexually dimorphic, and how they might be organized into functional circuits. - Results - We used genetic methods to define 100 distinct classes of *fru* neuron, which we compiled into a digital 3D atlas at cellular resolution. We determined the polarity of many of these neurons and computed their likely patterns of connectivity, thereby assembling them into a neural circuit that extends from sensory input to motor output. The cellular organization of this circuit reveals neuronal pathways in the brain that are likely to integrate multiple sensory cues from other flies and to issue descending control signals to motor circuits in the thoracic ganglia. We identified 11 anatomical dimorphisms within this circuit: neurons that are male specific, are more numerous in males than females, or have distinct arborization patterns in males and females. - Conclusions - The cellular organization of the *fru* circuit suggests how multiple distinct sensory cues are integrated in the fly's brain to drive sex-specific courtship behavior. We propose that sensory processing and motor control are mediated through circuits that are largely similar in males and females. Sex-specific behavior may instead arise through dimorphic circuits in the brain and nerve cord that differentially couple sensory input to motor output. - Highlights - Genetic dissection defines 100 distinct types of *fru* neuron - A digital atlas of the *fru* circuit is constructed with cellular resolution - Projections, polarity, and predicted connectivity suggest pathways of information flow - Dimorphisms in key integrative centers may explain sex differences in behavior

Nerve cells and animal behaviour Flashcards

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