PR-comparative brain anatomy
From Mbscientific_wiki
[edit] hippocampus
Spatial memory and hippocampal pallium through vertebrate evolution: insights from reptiles and teleost fish
F. Rodrígueza, J. C. Lópeza, J. P. Vargasa, C. Broglioa, Y. Gómeza and C. Salasa, a Laboratorio de Psicobiología, Universidad de Sevilla, Campus Santiago Ramón y Cajal, Sevilla, Spain
Available online 21 March 2002.
Abstract: The forebrain of vertebrates shows great morphological variation and specialized adaptations. However, an increasing amount of neuroanatomical and functional data reveal that the evolution of the vertebrate forebrain could have been more conservative than previously realized. For example, the pallial region of the teleost telencephalon contains subdivisions presumably homologous with various pallial areas in amniotes, including possibly a homologue of the medial pallium or hippocampus. In mammals and birds, the hippocampus is critical for encoding complex spatial information to form map-like cognitive representations of the environment. Here, we present data showing that the pallial areas of reptiles and fish, previously proposed as homologous to the hippocampus of mammals and birds on an anatomical basis, are similarly involved in spatial memory and navigation by map-like or relational representations of the allocentric space. These data suggest that early in vertebrate evolution, the medial pallium of an ancestral fish group that gave rise to the extant vertebrates became specialized for processing and encoding complex spatial information, and that this functional trait has been retained through the evolution of each independent vertebrate lineage.
[edit] basal ganglia
Paper: Structural and functional evolution of the basal ganglia in vertebrates
Anton Reinera, *, Loreta Medinab and C. Leo Veenmanc a Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee—Memphis, 855 Monroe Avenue, Memphis, TN 38163, USA b Department of Morphological Sciences, Facultad de Medicina, Universidad de Murcia, Campus de Espinardo, Murcia 30100, Spain c Behavioral Biology Laboratory, Institute of Toxicology, Swiss Federal Institute of Technology, CH-8603 Schwerzenbach, Switzerland Accepted 12 May 1998. Available online 22 December 1998.
Abstract: While a basal ganglia with striatal and pallidal subdivisions is1 clearly present in many extant anamniote species, this basal ganglia is cell sparse and receives only a relatively modest tegmental dopaminergic input and little if any cortical input. The major basal ganglia influence on motor functions in anamniotes appears to be exerted via output circuits to the tectum. In contrast, in modern mammals, birds, and reptiles (i.e., modern amniotes), the striatal and pallidal parts of the basal ganglia are very neuron-rich, both consist of the same basic populations of neurons in all amniotes, and the striatum receives abundant tegmental dopaminergic and cortical input. The functional circuitry of the basal ganglia also seems very similar in all amniotes, since the major basal ganglia influences on motor functions appear to be exerted via output circuits to both cerebral cortex and tectum in sauropsids (i.e., birds and reptiles) and mammals. The basal ganglia, output circuits to the cortex, however, appear to be considerably more developed in mammals than in birds and reptiles. The basal ganglia, thus, appears to have undergone a major elaboration during the evolutionary transition from amphibians to reptiles. This elaboration may have enabled amniotes to learn and/or execute a more sophisticated repertoire of behaviors and movements, and this ability may have been an important element of the successful adaptation of amniotes to a fully terrestrial habitat. The mammalian lineage appears, however, to have diverged somewhat from the sauropsid lineage with respect to the emergence of the cerebral cortex as the major target of the basal ganglia circuitry devoted to executing the basal ganglia-mediated control of movement.
Paper:The Journal of Comparative Neurology
An immunohistochemical study of the telencephalon of the african lungfish, Protopterus annectens Anton Reiner 1, R. Glenn Northcutt 2 1Department of Anatomy and Cell Biology, The University of Michigan, Ann Arbor, Michigan 48109 2The Division of Biological Sciences, The University of Michigan, Ann Arbor, Michigan 48109
Abstract: The telencephalon of the African lungflsh, Protopterus annectens, was studied by immunohistochemical techniques in order to identify the major subdivisions of the telencephalon and determine the possible homologues of these subdivisions, if any, in other vertebrates. The distributions of four different neuropeptides (substance P, leucine-enkephalin, avian pancreatic polypeptide, and LANT6), a neurotransmitter (serotonin), and a neurotransmitter-related enzyme that is involved in catecholamine synthesis (tyrosine hydroxylase) were examined. The resultant labeling patterns indicated that the telencephalon of lungfish consists of three major subdivisions-a rostrally and dorsally situated olfactory bulb, a dorsally situated pallial region located caudal to the olfactory bulbs, and a ventrally situated subpallial regions. The dorsal and lateral pallial regions, which both receive secondary olfactory input, are somewhat, distinct from one another cytoarchitectonically, but their immunohistochemical, labeling characteristics did not differ. Thus, the lateral pallium and the dorsal pallium together appear to constitute an olfactory pallium in lungfishes. The medial pallium was found to consist of three immunohisthochemically distinct subdivisions-a dorsal cell group, an intermediate cell group, and a ventral cell group. These medial pallial fields extend throughout the entire rostrocaudal extent of the medial wall of the telencephalon. Although one or more of these medial pallial cell groups may be homologous to specific portions of the medial pallium in land vertebrates, no specific similarities were observed to support any proposed one-to-one correspondences. The possibility that one or more of the medial pallial cell groups of lungfishes correspond to cell groups located in the dorsal pallium of land vertebrates could not be excluded. The subpallium is divided into lateral, medial, and caudal subdivisions. The lateral subdivision appears to be homologous to the basal ganglia of land vertebrates since it contains neuropeptide/neurotransmitter-specific neuronal populations that are characterstic of the striatal and pallidal portions of the basal ganglia of amniotes. The medial subdivision of the subpallium shows the topographic and immunohistochemical characteristics of the septal region and the nucleus accumbens region of the amniote telencephalon. The caudal subpallium does not show any distinctive immunohistochemical labeling characteristics and its possible homologue in land vertebrates is unclear. The present results indicate that the evolution of the telencephalon during the transition from fish to amphibians must have been characterized by a striking conservatism in the case of the subpallium. A basal ganglia and a septal region having many of the characteristics of those of land vertebrates appear to be present in the telencephalon of lungfishes, thereby suggesting that these cell groups were already present in the brains of the earliest lobe-finned fishes. Although the present results suggest that a lateral pallium, or olfactory cortex, was present in the telencephalon of ancestral lobe-finned fish, they do not provide evidence to support the existence in lobe-finned fish of a forerunner of the dorsal pallium of land vertebrates. Further, it is unclear whether the medial pallial cell groups in lungfishes are homologous to cell groups in the medial telencephalic walls of land vertebrates.
Paper: Dissociating Hippocampal versus Basal Ganglia Contributions to Learning and Transfer
MIT Press- Journal of Cognitive Science:
Catherine E. Myers, Daphna Shohamy, Mark A. Gluck and Steven Grossman
Rutgers University
Alan Kluger
City University of New York
Steven Ferris and James Golomb
New York University Medical Center
Geoffrey Schnirman
Fordham University
Ronald Schwartz
Hattiesburg Clinic
Abstract:
Based on prior animal and computational models, we propose a double dissociation between the associative learning deficits observed in patients with medial temporal (hippocampal) damage versus patients with Parkinson's disease (basal ganglia dysfunction). Specifically, we expect that basal ganglia dysfunction may result in slowed learning, while individuals with hippocampal damage may learn at normal speed. However, when challenged with a transfer task where previously learned information is presented in novel recombinations, we expect that hippocampal damage will impair generalization but basal ganglia dysfunction will not. We tested this prediction in a group of healthy elderly with mild-to-moderate hippocampal atrophy, a group of patients with mild Parkinson's disease, and healthy controls, using an "acquired equivalence" associative learning task. As predicted, Parkinson's patients were slower on the initial learning but then transferred well, while the hippocampal atrophy group showed the opposite pattern: good initial learning with impaired transfer. To our knowledge, this is the first time that a single task has been used to demonstrate a double dissociation between the associative learning impairments caused by hippocampal versus basal ganglia damage/dysfunction. This finding has implications for understanding the distinct contributions of the medial temporal lobe and basal ganglia to learning and memory.
Video: http://www.youtube.com/watch?v=2Ei6wFJ9kCc
