Cellular Scaling Rules for the Brains of Marsupials: Not as “Primitive” as Expected
In the effort to understand the evolution of mammalian brains, we have found that common relationships between brain structure mass and numbers of nonneuronal (glial and vascular) cells apply across eutherian mammals, but brain structure mass scales differently with numbers of neurons across structures and across primate and nonprimate clades. This suggests that the ancestral scaling rules for mammalian brains are those shared by extant nonprimate eutherians - but do these scaling relationships apply to marsupials, a sister group to eutherians that diverged early in mammalian evolution? Here we examine the cellular composi...
Source: Brain, Behavior and Evolution - January 26, 2017 Category: Neurology Source Type: research
Comparison of Dolphins' Body and Brain Measurements with Four Other Groups of Cetaceans Reveals Great Diversity
We compared mature dolphins with 4 other groupings of mature cetaceans. With a large data set, we found great brain diversity among 5 different taxonomic groupings. The dolphins in our data set ranged in body mass from about 40 to 6,750 kg and in brain mass from 0.4 to 9.3 kg. Dolphin body length ranged from 1.3 to 7.6 m. In our combined data set from the 4 other groups of cetaceans, body mass ranged from about 20 to 120,000 kg and brain mass from about 0.2 to 9.2 kg, while body length varied from 1.21 to 26.8 m. Not all cetaceans have large brains relative to their body size. A few dolphins near human body size have human...
Source: Brain, Behavior and Evolution - January 25, 2017 Category: Neurology Source Type: research
Characterization of NADPH Diaphorase- and Doublecortin-Positive Neurons in the Lizard Hippocampal Formation
The lizard cortex has remarkable similarities with the mammalian hippocampus. Both regions process memories, have similar cytoarchitectural properties, and are important neurogenic foci in adults. Lizards show striking levels of widespread neurogenesis in adulthood and can regenerate entire cortical areas after injury. Nitric oxide (NO) is an important regulatory factor of mammalian neurogenesis and hippocampal function. However, little is known about its role in nonmammalian neurogenesis. Here, we analyzed the distribution, morphology, and dendritic complexity (Neurolucida reconstructions) of NO-producing neurons through ...
Source: Brain, Behavior and Evolution - January 24, 2017 Category: Neurology Source Type: research
Zebrin II Is Expressed in Sagittal Stripes in the Cerebellum of Dragon Lizards (Ctenophorus sp.)
Aldolase C, also known as zebrin II (ZII), is a glycolytic enzyme that is expressed in cerebellar Purkinje cells of the vertebrate cerebellum. In both mammals and birds, ZII is expressed heterogeneously, such that there are sagittal stripes of Purkinje cells with high ZII expression (ZII+) alternating with stripes of Purkinje cells with little or no expression (ZII-). In contrast, in snakes and turtles, ZII is not expressed heterogeneously; rather all Purkinje cells are ZII+. Here, we examined the expression of ZII in the cerebellum of lizards to elucidate the evolutionary origins of ZII stripes in Sauropsida. We focused o...
Source: Brain, Behavior and Evolution - January 19, 2017 Category: Neurology Source Type: research
Zebrin II Is Expressed in Sagittal Stripes in the Cerebellum of Dragon Lizards ( < b > < i > Ctenophorus < /i > < /b > sp < b > < i > . < /i > < /b > )
Aldolase C, also known as zebrin II (ZII), is a glycolytic enzyme that is expressed in cerebellar Purkinje cells of the vertebrate cerebellum. In both mammals and birds, ZII is expressed heterogeneously, such that there are sagittal stripes of Purkinje cells with high ZII expression (ZII+) alternating with stripes of Purkinje cells with little or no expression (ZII-). In contrast, in snakes and turtles, ZII is not expressed heterogeneously; rather all Purkinje cells are ZII+. Here, we examined the expression of ZII in the cerebellum of lizards to elucidate the evolutionary origins of ZII stripes in Sauropsida. We focused o...
Source: Brain, Behavior and Evolution - January 18, 2017 Category: Neurology Source Type: research
Endocranial Morphology of the Extinct North American Lion (Panthera atrox)
The extinct North American lion (Panthera atrox) is one of the largest felids (Mammalia, Carnivora) to have ever lived, and it is known from a plethora of incredibly well-preserved remains. Despite this abundance of material, there has been little research into its endocranial anatomy. CT scans of a skull ofP. atroxfrom the Pleistocene La Brea Tar pits were used to generate the first virtual endocranium for this species and to elucidate previously unknown details of its brain size and gross structure, cranial nerves, and inner-ear morphology. Results show that its gross brain anatomy is broadly similar to that of other pan...
Source: Brain, Behavior and Evolution - January 17, 2017 Category: Neurology Source Type: research
Endocranial Morphology of the Extinct North American Lion ( < b > < i > Panthera atrox < /i > < /b > )
The extinct North American lion (Panthera atrox) is one of the largest felids (Mammalia, Carnivora) to have ever lived, and it is known from a plethora of incredibly well-preserved remains. Despite this abundance of material, there has been little research into its endocranial anatomy. CT scans of a skull ofP. atroxfrom the Pleistocene La Brea Tar pits were used to generate the first virtual endocranium for this species and to elucidate previously unknown details of its brain size and gross structure, cranial nerves, and inner-ear morphology. Results show that its gross brain anatomy is broadly similar to that of other pan...
Source: Brain, Behavior and Evolution - January 16, 2017 Category: Neurology Source Type: research
Evolution of Gyrification in Carnivores
The order Carnivora is a large and highly diverse mammalian group with a long and well-documented evolutionary history. Nevertheless, our knowledge on the degree of cortical folding (or degree of gyrification) is limited to just a few species. Here we investigate the degree of cortical folding in 64 contemporary and 37 fossil carnivore species. We do so by measuring the length of gyri impressions on endocranial casts. We use this approach because we have found that there is a very good correlation between the degree of cortical folding and the relative length of the gyri that are exposed on the outer surface of the hemisph...
Source: Brain, Behavior and Evolution - January 9, 2017 Category: Neurology Source Type: research
Telencephalic Neuronal Activation Associated with Spatial Memory in the Terrestrial Toad Rhinella arenarum: Participation of the Medial Pallium during Navigation by Geometry
Amphibians are central to discussions of vertebrate evolution because they represent the transition from aquatic to terrestrial life, a transition with profound consequences for the selective pressures shaping brain evolution. Spatial navigation is one class of behavior that has attracted the interest of comparative neurobiologists because of the relevance of the medial pallium/hippocampus, yet, surprisingly, in this regard amphibians have been sparsely investigated. In the current study, we trained toads to locate a water goal relying on the boundary geometry of a test environment (Geometry-Only) or boundary geometry coup...
Source: Brain, Behavior and Evolution - November 25, 2016 Category: Neurology Source Type: research
Erratum
Brain Behav Evol 2016;88:147 (Source: Brain, Behavior and Evolution)
Source: Brain, Behavior and Evolution - November 23, 2016 Category: Neurology Source Type: research
Comparative Analysis of Gene Regulatory Network Components in the Auditory Hindbrain of Mice and Chicken
The neurons in the mammalian and avian auditory hindbrain nuclei share a number of significant morphological and physiological properties for fast, secure and precise neurotransmission, such as giant synapses, voltage-gated K+ channels and fast AMPA receptors. Based on the independent evolution of the middle ear in these two vertebrate lineages, on different embryonic origins of the nuclei and on marked differences on the circuit level, these similarities are assumed to reflect convergent evolution. Independent acquisition of similar phenotypes can be produced by divergent evolution of genetic mechanisms or by similar mole...
Source: Brain, Behavior and Evolution - November 18, 2016 Category: Neurology Source Type: research
South American Weakly Electric Fish (Gymnotiformes) Are Long-Wavelength-Sensitive Cone Monochromats
Losses of cone opsin genes are noted in animals that are nocturnal or rely on senses other than vision. We investigated the cone opsin repertoire of night-active South American weakly electric fish. We obtained opsin gene sequences from genomic DNA of 3 gymnotiforms(Eigenmannia virescens, Sternopygus macrurus, Apteronotus albifrons) and the assembled genome of the electric eel(Electrophorus electricus). We identified genes for long-wavelength-sensitive (LWS) and medium-wavelength-sensitive cone opsins (RH2) and rod opsins (RH1). Neither of the 2 short-wavelength-sensitive cone opsin genes were found and are presumed lost. ...
Source: Brain, Behavior and Evolution - November 8, 2016 Category: Neurology Source Type: research
Seasonal Variation in Group Size Is Related to Seasonal Variation in Neuropeptide Receptor Density
We examined binding sites for125I-vasoactive intestinal polypeptide (VIP),125I-sauvagine (SG, a ligand for corticotropin-releasing hormone receptors) and125I-ornithine vasotocin analog (OVTA, a ligand for the VT3 nonapeptide). For all species and ligands, brain areas that exhibited a seasonal pattern in binding density were characterized by a winter increase. Compared to nonflocking species, seasonally flocking species showed different binding patterns in multiple brain areas. Furthermore, we found that winter flocking was associated with elevated winter125I-VIP binding density in the medial amygdala, as well as125I-VIP an...
Source: Brain, Behavior and Evolution - October 27, 2016 Category: Neurology Source Type: research
Spatiotemporal Development of the Orexinergic (Hypocretinergic) System in the Central Nervous System of < b > < i > Xenopus laevis < /i > < /b >
We examined the onset of the orexinergic system, demonstrated to be involved in appetite regulation, using antibodies against mammalian orexin-A and orexin-B peptides. Simultaneous detection of orexins with other territorial markers was used to assess the precise location of the orexinergic cells in the hypothalamus, analyzed within a segmental paradigm. Double staining of orexins and tyrosine hydroxylase served to evaluate possible interactions with the catecholaminergic systems. At early embryonic stages, the first OX-ir cells were detected in the hypothalamus and, soon after, long descending projections were observed th...
Source: Brain, Behavior and Evolution - October 21, 2016 Category: Neurology Source Type: research
The Neocortex of Indian River Dolphins (Genus Platanista): Comparative, Qualitative and Quantitative Analysis
We investigated the morphology of four primary neocortical projection areas (somatomotor, somatosensory, auditory, visual) qualitatively and quantitatively in the Indian river dolphins(Platanista gangetica gangetica, P. gangetica minor) with histological and stereological methods. For comparison, we included brains of other toothed whale species. Design-based stereology was applied to the primary neocortical areas (M1, S1, A1, V1) of the Indian river dolphins and compared to those of the bottlenose dolphin with respect to layers III and V. These neocortical fields were identified using existing electrophysiological and mor...
Source: Brain, Behavior and Evolution - October 13, 2016 Category: Neurology Source Type: research
