Showing papers in "Brain Behavior and Evolution in 2006"
TL;DR: The presence of RET- and GFR-like genes in insects suggests that a ProtoGFR and a ProtoRET arose early in the evolution of bilaterian animals, but when the ProtoGFL diverged from existing transforming growth factor (TGFβ)-like proteins remains unclear.
Abstract: Four different ligand-receptor binding pairs of the GDNF (glial cell line-derived neurotrophic factor) family exist in mammals, and they all signal via the transmembrane RET receptor tyrosine kinase. In addition, GRAL (GDNF Receptor Alpha-Like) protein of unknown function and Gas1 (growth arrest specific 1) have GDNF family receptor (GFR)-like domains. Orthologs of the four GFRα receptors, GRAL and Gas1 are present in all vertebrate classes. In contrast, although bony fishes have orthologs of all four GDNF family ligands (GFLs), one of the ligands, neurturin, is absent in clawed frog and another, persephin, is absent in the chicken genome. Frog GFRα2 has selectively evolved possibly to accommodate GDNF as a ligand. The key role of GDNF and its receptor GFRα1 in enteric nervous system development is conserved from zebrafish to humans. The role of neurturin, signaling via GFRα2, for parasympathetic neuron development is conserved between chicken and mice. The role of artemin and persephin that signal via GFRα3 and GFRα4, respectively, is unknown in non-mammals. The presence of RET- and GFR-like genes in insects suggests that a ProtoGFR and a ProtoRET arose early in the evolution of bilaterian animals, but when the ProtoGFL diverged from existing transforming growth factor (TGFβ)-like proteins remains unclear. The four GFLs and GFRαs were presumably generated by genome duplications at the origin of vertebrates. Loss of neurturin in frog and persephin in chicken suggests functional redundancy in early tetrapods. Functions of non-mammalian GFLs and prechordate RET and GFR-like proteins remain to be explored.
96 citations
TL;DR: In analyses using both species level data and phylogenetically independent contrasts, relative brain size was larger in behaviorally flexible species and relative neocortex volume was significantly reduced in bats that aerially hawk prey primarily in open spaces.
Abstract: We investigated the potential relationships between foraging strategies and relative brain and brain region volumes in predatory (animal-eating) echolocating bats The species we considered represent the ancestral state for the order and approximately 70% of living bat species The two dominant foraging strategies used by echolocating predatory bats are substrate-gleaning (taking prey from surfaces) and aerial hawking (taking airborne prey) We used species-specific behavioral, morphological, and ecological data to classify each of 59 predatory species as one of the following: (1) ground gleaning, (2) behaviorally flexible (ie, known to both glean and hawk prey), (3) clutter tolerant aerial hawking, or (4) open-space aerial hawking In analyses using both species level data and phylogenetically independent contrasts, relative brain size was larger in behaviorally flexible species Further, relative neocortex volume was significantly reduced in bats that aerially hawk prey primarily in open spaces Conversely, our foraging behavior index did not account for variability in hippocampus and inferior colliculus volume and we discuss these results in the context of past research
89 citations
TL;DR: It is proposed that developmental and adult plasticity of the synaptic circuitry in the mushroom-body calyx might underlie caste- and age-specific adaptations in behavior.
Abstract: Diversity in behavior plays a crucial role for the division of labor in insect societies. Social insects such as honeybees provide excellent model systems to investigate neuronal principles underlying
86 citations
TL;DR: It is suggested that the retinal topography did not accompany changes in the foraging ecology throughout evolutionary history for these species of tyrant flycatchers, and they shared a similar topographic arrangement of neuronal density in the ganglion cell layer.
Abstract: Tyrant flycatchers comprise the largest group of passerine birds of the Neotropical region but their retinal organization is unknown. The great kiskadee, Pitangus sulphuratus, is ca
84 citations
TL;DR: It appears certain that the formation of the multi-gene copy neurotrophin and Trk receptor families at the stem of vertebrates has provided a foundation from which the various functions and pleiotropic effects produced by each of the four extant neurotrophins have evolved.
Abstract: Neurotrophins are structurally related neurotrophic polypeptide factors that regulate neuronal differentiation and are essential for neuronal survival, neurite growth and plasticity. It has until very recently been thought that the neurotrophin system appeared with the vertebrate species, but identification of a cephalochordate neurotrophin receptor (Trk), and more recently neurotrophin sequences in several genomes of deuterostome invertebrates, show that the system already existed at the stem of the deuterostome group. Comparative genomics supports the hypothesis that two whole genome duplications produced many of the vertebrate gene families, among those the neurotrophin and Trk families. It remains to be proven to what extent the whole genome duplications have driven macroevolutionary change, but it appears certain that the formation of the multi-gene copy neurotrophin and Trk receptor families at the stem of vertebrates has provided a foundation from which the various functions and pleiotropic effects produced by each of the four extant neurotrophins have evolved.
77 citations
TL;DR: It is proposed that the connectivity of the amphibian telencephalon portends a capacity for multi-modal association in a limbic system largely similar to that of amniote vertebrates.
Abstract: The histology of amphibian brains gives an impression of relative simplicity when compared with that of reptiles or mammals. The amphibian telencephalon is small and contains comparatively few and large neurons, which in most parts constitute a dense periventricular cellular layer. However, the view emerging from the last decade is that the brains of all tetrapods, including amphibians, share a general bauplan resulting from common ancestry and the need to perform similar vital functions. To what extent this common organization also applies to higher brain functions is unknown due to a limited knowledge of the neurobiology of early vertebrates. The amygdala is widely recognized as a brain center critical for basic forms of emotional learning (e.g., fear conditioning) and its structure in amphibians could suggest how this capacity evolved. A functional systems approach is used here to synthesize the results of our anatomical investigations of the amphibian amygdala. It is proposed that the connectivity of the amphibian telencephalon portends a capacity for multi-modal association in a limbic system largely similar to that of amniote vertebrates. One remarkable exception is the presence of new sensory-associative regions of the amygdala in amniotes: the posterior dorsal ventricular ridge plus lateral nuclei in reptiles and the basolateral complex in mammals. These presumably homologous regions apparently are capable of modulating the phylogenetically older central amygdala and allow more complex forms of emotional learning.
75 citations
TL;DR: Allometric and phylogenetic effects exert the strongest effects and developmental mode a weak effect on avian cerebellar foliation, and the phylogenetic distribution of highly foliated cerebella suggests that cognitive and/or behavioral differences play a role in the evolution of the cerebellum.
Abstract: Despite the conservative circuitry of the cerebellum, there is considerable variation in the shape of the cerebellum among vertebrates. One aspect of cerebellar morphology that is of particular interest is the degree of folding, or foliation, of the cerebellum and its functional significance. Here, we present the first comprehensive analysis of variation in cerebellar foliation in birds with the aim of determining the effects that allometry, phylogeny and development have on species differences in the degree of cerebellar foliation. Using both conventional and phylogenetically based statistics, we assess the effects of these variables on cerebellar foliation among 91 species of birds. Overall, our results indicate that allometry exerts the strongest effect and accounts for more than half of the interspecific variation in cerebellar foliation. In addition, we detected a significant phylogenetic effect. A comparison among orders revealed that several groups, corvids, parrots and seabirds, have significantly more foliated cerebella than other groups, after accounting for allometric effects. Lastly, developmental mode was weakly correlated with relative cerebellar foliation, but incubation period and fledging age were not. From our analyses, we conclude that allometric and phylogenetic effects exert the strongest effects and developmental mode a weak effect on avian cerebellar foliation. The phylogenetic distribution of highly foliated cerebella also suggests that cognitive and/or behavioral differences play a role in the evolution of the cerebellum.
65 citations
TL;DR: It was found that water restriction caused a reduction in circulating LH concentrations and that testis volume was more likely to decrease in water restricted than in control birds, suggesting that in these opportunistic breeders, an inhibition of parts of the reproductive axis is not necessarily correlated with full inactivation of reproductive potential.
Abstract: Opportunistically breeding species offer the unique opportunity to understand mechanisms in reproductive physiology that allow for extreme flexibility in the regulation of reproduction. We studied a w
45 citations
TL;DR: Results suggest that a functional neurotrophin system was already present at the beginning of deuterostome evolution, but was lost in ascidians, and represents one of the earliest events in the expansion of the tumor necrosis factor receptor superfamily.
Abstract: Nucleotide sequences encoding orthologs of neurotrophins and their receptors, p75NTR and Trk receptors, have been identified in the sea urchin Strongylocentrotus purpuratus
43 citations
TL;DR: A striking dichotomy between the extraordinary species diversity of brain receptor patterns when compared to the highly conserved brain distributions of their respective ligands is demonstrated.
Abstract: Brain receptor patterns for the corticotropin-releasing factor (CRF) receptors, CRF1 and CRF2, are dramatically different between monogamous and promiscuous vole species, and CRF physiologically regul
42 citations
TL;DR: This first comparison of cerebellar morphology within the avian order Caprimulgiformes is presented, demonstrating that the owlet-nightjars, nightjars and potoos are more similar to apodiforms than they are to other taxa and that the monotypic oilbird possesses a cerebellum that resembles an owl more than a nightjar.
Abstract: Interspecific variation in the structure of the avian cerebellum is poorly understood. We present the first comparison of cerebellar morphology within the avian order Caprimulgiformes. Using a range of qualitative descriptions and quantitative measurements of cerebellar morphology we compared caprimulgiform birds with hummingbirds and swifts (Apodiformes) and owls (Strigiformes), two groups that are putative sister taxa to the Caprimulgiformes. Our results demonstrate that the owlet-nightjars (Aegothelidae), nightjars (Caprimulgidae) and potoos (Nyctibiidae) are more similar to apodiforms than they are to other taxa. All of these species have a reduced anterior lobe characterized by particularly small folia II and III and a relatively large posterior lobe. The frogmouths (Podargidae) possess a markedly different cerebellum that is more similar to that of owls than any of the caprimulgiform or apodiform birds. The monotypic oilbird (Steatornis caripensis, Steatornithidae) possesses a cerebellum with some nightjar-like features and some owl-like features, but overall it too resembles an owl more than a nightjar. This cerebellar diversity within the order Caprimulgiformes has significant implications for understanding the evolutionary relationships within the order, how the avian cerebellum has evolved and whether interspecific differences in cerebellar morphology reflect behavior.
TL;DR: The data suggest that many previously made assumptions about western scrub-jays as less specialized food hoarders might be an oversimplification and that simple categorization of species into specialized and non-specialized hoarder might not provide useful insights into the evolution of memory and the hippocampus.
Abstract: Food caching has been linked to better performance on spatial memory tasks and enlarged hippocampal volume in both birds and mammals. Within food-caching birds, it has also been predicted that species
TL;DR: Although sex differences in dorsal cortex volume were not observed, males had a significantly larger medial cortex relative to telencephalon volume, and relative hippocampal or medial cortex volume was positively correlated with patterns of spatial use.
Abstract: In non-avian reptiles the medial and dorsal cortices are putative homologues of the hippocampal formation in mammals and birds. Studies on mammals and birds commonly report neuro-ecological correlations between hippocampal volume and aspects of spatial ecology. We examined the relationship between putative homologous cortical volumes and spatial use in a population of the squamate reptile, Agkistrodon piscivorus, that exhibits sex differences in spatial use. Do male A. piscivorus that inhabit larger home ranges than females also have larger putative hippocampal volumes? Male and female brains were sectioned and digitized to quantify regional cortical volumes. Although sex differences in dorsal cortex volume were not observed, males had a significantly larger medial cortex relative to telencephalon volume. Similar to studies on mammals and birds, relative hippocampal or medial cortex volume was positively correlated with patterns of spatial use. We demonstrate volumetric sex differences within a reptilian putative hippocampal homologue.
TL;DR: The results demonstrate that tropical birds can exhibit neural changes similar to those exhibited in higher latitude birds, however, these tropical populations appear to be using supplementary cues in a similar way to higher latitude species using an initial predictive cue (photoperiod).
Abstract: Timing of seasonal reproduction in high latitude vertebrates is generally regulated by photoperiodic cues. Increasing day length in the spring is associated with changes in the brain that are responsible for mediating reproductive activities. A primary example of this is the increased content of gonadotropin-releasing hormone (GnRH) in the preoptic area of the hypothalamus in birds as they enter the spring breeding season. Increased GnRH activity stimulates the release of luteinizing hormone and follicle-stimulating hormone from the anterior pituitary. These gonadotropins induce growth of the gonads and release of sex steroids which act on the brain to mediate reproductive behaviors. By contrast, seasonal breeding in the tropics can occur in the absence of significant changes in photoperiod. To our knowledge, no studies have investigated whether seasonal breeding in free-living tropical vertebrates is associated with seasonal changes in the GnRH system. We studied two populations of rufous-collared sparrows (Zonotrichia capensis) at the equator, separated by only 25 km, but with asynchronous reproductive phenologies associated with local climate and independent of photoperiodic cues. We collected brains and measured GnRH immunoreactivity (GnRH-ir) during each population's breeding and non-breeding periods. Breeding males had larger, but not more, GnRH-ir cells than non-breeding birds. The plasticity of the GnRH system was associated with local climate, such that the two populations exhibited asynchronous changes in GnRH-ir despite experiencing identical photoperiod conditions. Our results demonstrate that tropical birds can exhibit neural changes similar to those exhibited in higher latitude birds. However, these tropical populations appear to be using supplementary cues (e.g., rainfall, temperature, food availability) in a similar way to higher latitude species using an initial predictive cue (photoperiod). These results raise questions about the evolution of reliance upon photoperiodism and the strength of reproductive responses to other environmental cues in congeners from higher latitudes. The ability to respond to a multitude of environmental cues might be part of the ancestral condition, and the subsequent obligate photoperiodism in high-latitude congeners could reflect a loss of flexibility in response to environmental signals.
TL;DR: The evolution of the Trk superfamily is traced and possible conserved functional roles are discussed, including a unifying theme of target recognition by growing axons, proposing that an important driving force for the divergence of receptors is the ease of divergence of their ligands.
Abstract: Most growth factors and their receptors have been strongly conserved during evolution. In contrast, Trks (Tropomyosin-related kinases) and related receptors in the Trk superfamily, Rors (receptor tyrosine kinase-like orphan receptors), Musks (muscle specific kinases) and Ddrs (discoidin domain receptor family), appear to be ancient, but their function has been lost in multiple lineages and the roles for the receptors have been modified over time. We will trace the evolution of the Trk superfamily and discuss possible conserved functional roles, including a unifying theme of target recognition by growing axons. We present an analogy between the evolution of G-protein-coupled receptors and receptor tyrosine kinases (RTKs), proposing that an important driving force for the divergence of receptors is the ease of divergence of their ligands.
TL;DR: The authors' data indicate that in the winter flounder retina the choice of new opsin species and the cellular rearrangement of the mosaic proceed independently, suggesting that the production of the precise cone mosaic arrangement is not due to a stereotyped series of sequential cellular inductions, but rather might be the product of a set of distinct, flexible processes that rely on plasticity in cell phenotype.
Abstract: The retinal cone mosaic of the winter flounder, Pseudopleuronectes americanus , is extensively remodeled during metamorphosis when its visual system shifts from monochromatic to tric
TL;DR: Gene deletion studies in mice provide evidence for a complex regulation of neuronal survival of sensory ganglion cells by different neurotrophins, and increasing diversity of neurotrophin ligands and their receptors and a more complex dependency of neurons on neurotrophs might have facilitated the formation of at least some new neuronal entities.
Abstract: To better understand the role of multiple neurotrophin ligands and their receptors in vertebrate brain evolution, we examined the distribution of trk neurotrophin receptors in representatives of sever
TL;DR: The behavioral response phenotype of hybrid males created by mating two heliothine moth species was influenced by genetic factors inherited from both parental species, and suggested that in addition to Z11–16:Ald, hybrid males required either Z9–16):Ald (likeH. subflexamales) or Z9-tetradecenal (like H. virescens males).
Abstract: Shifts in male preference for qualitatively different pheromone blends appear to have played a fundamental role in the divergence of olfactory communication and evolution of moth species. As an initia
TL;DR: The monotreme olfactory bulb of two monotremes does not show any significant chemoarchitectural dissimilarities from eutheria, despite differences in mitral/tufted cell distribution.
Abstract: The cyto- and chemoarchitecture of the olfactory bulb of two monotremes (shortbeaked echidna and platypus) was studied to determine if there are any chemoarchitectural differences from therian mammals. Nissl staining in conjunction with enzyme reactivity for NADPH diaphorase, and immunoreactivity for calcium binding proteins (parvalbumin, calbindin and calretinin), neuropeptide Y, tyrosine hydroxylase and non-phosphorylated neurofilament protein (SMI-32 antibody) were applied to the echidna. Material from platypus bulb was Nissl stained, immunoreacted for calretinin, or stained for NADPH diaphorase. In contrast to eutherians, no immunoreactivity for either the SMI-32 antibody or calretinin was found in the mitral or dispersed tufted cells of the monotremes and very few parvalbumin or calbindin immunoreactive neurons were found in the bulb of the echidna. On the other hand, immunoreactivity for tyrosine hydroxylase in the echidna was similar in distribution to that seen in therians, and periglomerular and granule cells showed similar patterns of calretinin immunoreactivity to eutherians. Multipolar neuropeptide Y immunoreactive neurons were confined to the deep granule cell layer and underlying white matter of the echidna bulb and NADPH diaphorase reactivity was found in occasional granule cells, fusiform and multipolar cells of the inner plexiform and granule cell layers, as well as underlying white matter. Unlike eutherians, no NPY immunoreactive or NADPH diaphorase reactive neurons were seen in the glomerular layer. The bulb of the echidna was comparable in volume to prosimians of similar body weight, and its constituent layers were highly folded. In conclusion, the monotreme olfactory bulb does not show any significant chemoarchitectural dissimilarities from eutheria, despite differences in mitral/tufted cell distribution.
TL;DR: The most noteworthy shift in ORN responsiveness in hybrid males was an overall increase in sensitivity to Z9–14:Ald exhibited by Z9-16:A Ald-responsive ORNs, which are proposed to be logically explained by an increased or decreased co-expression of two different odorant receptors for each of these compounds on the same ORN.
Abstract: Single-cell electrophysiological recordings were obtained from olfactory receptor neurons (ORNs) in sensilla trichodea on male antennae of hybrids formed mainly by crossing female Heliothis s
TL;DR: Cellular and genetic evidence predicts the existence of neuronal trophic factors operating at least in the Drosophila embryo during axon guidance and, in the visual system, during the targeting of retinal axons in the brain.
Abstract: Trophic interactions in the vertebrate nervous system enable the adjustment of cell number and axon guidance, targeting and connectivity. Computational analysis of the sequenced Drosophila<
TL;DR: The distribution of CB1 in thebrain of T. granulosa was in many of the same sites previously observed in the brain of the anuran amphibian, Xenopus laevis, as well as those of different species of mammals, suggesting that endocannabinoid signaling pathways are conserved.
Abstract: Type I cannabinoid receptor (CB1) is a G-protein coupled receptor with a widespread distribution in the central nervous system in mammals. In a urodele amphibian, the rough-skinned newt (Tari
TL;DR: For a particular visual spatial location, the relative strength of descending visual input appears to contribute to a recruitment of a reticulospinal neuron population that generates a turn magnitude appropriate to the visual cue, and suggests that a retinotopic representation is preserved in the BEN.
Abstract: When startled by sound, goldfish make large turns away from a rostral stimulus and small responses away from caudal stimuli, suggesting that rostral startling stimuli recruit larger pools of reticulos
TL;DR: The results indicate that the behavioral phenotype of hybrid males can be linked to underlying central olfactory characteristics of Heliothis subflexa males.
Abstract: Pheromone-responsive olfactory interneurons were studied to determine the extent to which their physiological and morphological properties complemented the behavior and peripheral olfactory neurobiolo
TL;DR: The results show that the diverse basal ganglia neuron types each display different combinations of AMPA subunit localization that shape their responses to excitatory input.
Abstract: Corticostriatal and thalamostriatal projections utilize glutamate as a neurotransmitter in mammals and birds. The influence on striatum is mediated, in part, by ionotropic AMPA-type glutamate receptors, which are heteromers composed of GluR1-4 subunits. Although the cellular localization of AMPA-type subunits has been well characterized in mammalian basal ganglia, their localization in avian basal ganglia has not. We thus carried out light microscopic single- and double-label and electron microscopic single-label immunohistochemical studies of GluR1-4 distribution and cellular localization in pigeon basal ganglia. Single-label studies showed that the striatal neuropil is rich in GluR1, GluR2, and GluR2/3 immunolabeling, suggesting the localization of GluR1, GluR2 and/or GluR3 to the dendrites and spines of striatal projection neurons. Double-label studies and perikaryal size distribution determined from single-label material indicated that about 25% of enkephalinergic and 25% of substance P-containing striatal projection neuron perikarya contained GluR1, whereas GluR2 was present in about 75% of enkephalinergic neurons and all substance-P -containing neurons. The perikaryal size distribution for GluR2 compared to GluR2/3 suggested that enkephalinergic neurons might more commonly contain GluR3 than do substance P neurons. Parvalbuminergic and calretininergic striatal interneurons were rich in GluR1 and GluR4, a few cholinergic striatal interneurons possessed GluR2, but somatostatinergic striatal interneurons were devoid of all subunits. The projection neurons of globus pallidus all possessed GluR1, GluR2, GluR2/3 and GluR4 immunolabeling. Ultrastructural analysis of striatum revealed that GluR1 was preferentially localized to dendritic spines, whereas GluR2/3 was found in spines, dendrites, and perikarya. GluR2/3-rich spines were generally larger than GluR1 spines and more frequently possessed perforated post-synaptic densities. These results show that the diverse basal ganglia neuron types each display different combinations of AMPA subunit localization that shape their responses to excitatory input. For striatal projection neurons and parvalbuminergic interneurons, the combinations resemble those for the corresponding cell types in mammals, and thus their AMPA responses to glutamate are likely to be similar.
TL;DR: The evolutionary effects of domestication of mice therefore do not include changes to the eye in any variable measured, supporting the continued use of this animal as a model for a naturally adapted visual system.
Abstract: Evolutionary effects of domestication have been demonstrated for several body systems, including the eye, and for several vertebrate species, including the mouse. Given the importance of the laborator
TL;DR: Cephalopod mollusks represent the most complex nervous systems outside the vertebrate lineage, thus it is suggested that genome sequencing of different mollusk models will provide useful insights into the evolution of complex brains.
Abstract: The mechanisms underlying evolution of complex nervous systems are not well understood. In recent years there have been a number of attempts to correlate specific gene families or evolutionary processes with increased brain complexity in the vertebrate lineage. Candidates for evocation of complexity include genes involved in regulating brain size, such as neurotrophic factors or microcephaly-related genes; or wider evolutionary processes, such as accelerated evolution of brain-expressed genes or enhanced RNA splicing or editing events in primates. An inherent weakness of these studies is that they are correlative by nature, and almost exclusively focused on the mammalian and specifically the primate lineage. Another problem with genomic analyses is that it is difficult to identify functionally similar yet non-homologous molecules such as different families of cysteine-rich neurotrophic factors in different phyla. As long as comprehensive experimental studies of these questions are not feasible, additional perspectives for evolutionary and genomic studies will be very helpful. Cephalopod mollusks represent the most complex nervous systems outside the vertebrate lineage, thus we suggest that genome sequencing of different mollusk models will provide useful insights into the evolution of complex brains.
TL;DR: This paper is retracted because of a decimal place error for body weight of S. longirostris discovered subsequent to the on-line appearance of this paper, which causes the conclusions to change in a way that does not warrant publication.
Abstract: Due to a decimal place error for body weight of S. longirostris in table 1 we discovered subsequent to the on-line appearance of this paper (Brain Behav Evol 2006;68:218–228), we have had to re-analyz
TL;DR: It is suggested that vomeronasal receptor neurons born in late spring function throughout the summer and may be associated with the animals’ extensive territoriality during that period.
Abstract: In addition to the continuous low levels of neurogenesis typical of adult vertebrates to replace damaged chemoreceptor cells, red-backed salamanders (Plethodon cinereus) experience
TL;DR: The detailed innervation pattern of the sonic muscle of the red Piranha was investigated and it was concluded that the sonic muscles of the piranha are innervated by approximately 300 sonic motor neurons located only in the spinal cord.
Abstract: The red piranha, Pygocentrus nattereri , produces sounds by rapid contractions of a pair of extrinsic sonic muscles. The detailed innervation pattern of the sonic muscle of the red p