PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Brain evolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed1998

Methionine enkephalin immunoreactivity in the brain of the budgerigar (Melopsittacus undulatus): similarities and differences with respect to oscine songbirds.

The brain of the budgerigar (Melopsittacus undulatus), a small parrot that acquires new vocalizations throughout life, was examined for immunoreactivity to the opioid peptide methionine enkephalin (mENK). mENK is a highly prominent feature of the chemical architecture of the forebrain vocal system of oscine songbirds. Forebrain vocal control nuclei are believed to have evolved independently in parrots and songbirds (Streidter [1994] J. Comp. Neurol. 343:35-56); however, recent studies have found similarities in the neural organization of vocal control pathways in budgerigars and songbirds (Durand et al. [1997] J. Comp. Neurol. 377:179-206). Among the similarities are the existence of recursive pathways interconnecting vocal control neurons in the archistriatum, basal ganglia (i.e., lobus parolfactorius), and dorsal thalamus. In the present study, we found that all vocal control nuclei within the budgerigar forebrain exhibit prominent mENK-like immunoreactivity (ELI) in fibers and somata. We also found striking similarities between the morphology of ELI elements in budgerigar vocal control nuclei and that described previously in songbird vocal nuclei. Despite these similarities, the budgerigar dorsal striatopallidum (lobus parolfactorius, paleostriatum augmentatum, and paleostriatum primitivum) and somatomotor (anterior) archistriatum exhibit unique patterns of ELI. The dorsal striatopallidum contained far less ELI, whereas the archistriatum contained far more than would be expected on the basis of previous studies of opioid peptides in other avian species, including pigeons, chickens, and songbirds. These differences may reflect neural specializations unique to the budgerigar that contribute to the extraordinary flexibility of the vocal motor system of this species to acquire socially significant stimuli throughout life.

Animals↗
PubMedDate not supplied

Distributions and colocalization of neuropeptide Y and somatostatin in the goldfish brain.

The distributions of single- and double-labelled neuropeptide Y- (NPY-) and somatostatin-immunoreactive (SOM-IR) perikarya and processes were determined in the goldfish brain using immunoperoxidase and immunofluorescence techniques, respectively. In double-labelled material, it was evident that although these two peptides showed markedly similar distributions, they were colocalized in very few instances. A high degree of colocalization of NPY and SOM was noted in the neurons of the ventrolateral telencephalon (VI), the entopenduncular nucleus (NE) and, to a lesser extent, in the dorsocentral nucleus of the telencephalon (Dc). In Vl and NE, neurons showing NPY-IR displayed SOM-IR and vice versa. The only other instance of colocalization was that noted in the brainstem, where SOM and NPY were colocalized in the large cell bodies of the medial column of the vagal motor complex. Single-labelled SOM- and NPY-IR neurons shared a very similar distribution in various nuclei in the diencephalon and in the optic tectum. Colocalization was also noted within fibers throughout many nuclei of the telencephalon and within fibers innervating the swim bladder, one of the peripheral organs to which neurons of the medial column of the vagal motor complex project. Processes in the torus semicircularis and vagal lobe showed single-labelled immunoreactivity for both SOM and NPY in distinct laminar patterns. Large single-labelled SOM-IR terminals appeared to form pericellular baskets in the eminentia granularis of the cerebellum. Single-labelled NPY- or SOM-IR fibers were also found in the secondary gustatory nucleus and tract, the facial lobe, descending trigeminal tract, reticular formation and spinal cord. As in mammalian species, select groups of neurons in teleosts colocalize the neuropeptides SOM and NPY.

Animals↗
PubMed1981

Brain stem origins of spinal projections in the lizard Tupinambis nigropunctatus.

In order to study brainstem origins of spinal projections, ten Tegu lizards (Tupinambis nigropunctatus) received complete or partial hemisections of the spinal cord at the first or second cervical segment. Their brains were processed for conventional Nissl staining. The sections were surveyed for the presence or absence of retrograde chromatolysis. Based on analysis and comparison of results from lesions in the various spinal cord funiculi, the following conclusions were reached: The interstitial nucleus projects ipsilaterally to the spinal cord via the medial longitudinal fasciculus, as does the middle reticular field of the metencephalon. The red nucleus and dorsal vagal motor nucleus both project contralaterally to the spinal cord via the dorsal part of the lateral funiculus. The superior reticular field in the rostral metencephalon and the ventrolateral vestibular nucleus project ipsilaterally to the spinal cord via the ventral funiculus. The dorsolateral metencephalic nucleus and the ventral part of the inferior reticular nucleus of the myelencephalon both project ipsilaterally to the spinal cord via the dorsal part of the lateral funiculus. Several brainstem nuclei in Tupinambis project bilaterally to the spinal cord. The ventrolateral metencephalic nucleus, for example, projects ipsilaterally to the cord via the medial longitudinal fasciculus and contralaterally via the dorsal part of the lateral funiculus. The dorsal part of the inferior reticular nucleus projects bilaterally to the spinal cord via the dorsal part of the lateral funiculus. The nucleus solitarius complex projects contralaterally via the dorsal part of the lateral funiculus but ipsilaterally via the middle of the lateral funiculus. The inferior raphe nucleus projects bilaterally to the spinal cord via the middle part of the lateral funiculus. These data suggest that supraspinal projections in reptiles, especially reticulospinal systems, are more highly differentiated than previously thought. On the other hand, recent findings in cat, opossum, and monkey reveal that the organization of supraspinal pathways in the Tegu lizard bears a striking resemblance to that observed in mammals.

Animals↗
PubMed1993

Stathmin gene family: phylogenetic conservation and developmental regulation in Xenopus.

The ubiquitous cytoplasmic phosphoprotein stathmin was proposed to play a general role as an intracellular relay integrating diverse signals regulating the proliferation, differentiation, and functions of cells (Sobel, A. (1991) Trends Biol. Sci. 16, 301-305). It was originally identified in mammalian cells and tissues, but antibodies directed against the mammalian protein also recognized a stathmin-like 19-kDa protein in all vertebrate classes. The immunoreactive protein in Xenopus laevis displayed, like mammalian stathmin, several nonphosphorylated and phosphorylated heat-soluble forms with distinct migration on two-dimensional polyacrylamide gel electrophoresis. Screening of Xenopus oocyte and brain cDNA libraries with a rat stathmin cDNA probe allowed us to isolate several stathmin-related cDNA clones, among which clone XO35 encodes the Xenopus homologue of stathmin whose deduced amino acid sequence is 79% identical to and displays most of the characteristic structural features of the mammalian protein. In particular, one of the cAMP-dependent protein kinase and the two "proline-directed" kinase-specific sites known to be phosphorylated in rat stathmin are also present in the Xenopus protein. Furthermore, two other sets of clones coding for related proteins belonging to the stathmin gene family were also isolated; clone SC15 encodes the Xenopus homologue of SCG10, a rat protein specifically related to neuronal differentiation; clone XB3 encodes a protein which, as SCG10 or SC15, possesses a stathmin-like domain and an additional N-terminal extension but is more distant from SCG10 than SC15. Interestingly, the mRNA transcripts of Xenopus stathmin (XO35) appear ubiquitous, like stathmin in mammals, whereas the SC15 and XB3 mRNAs appeared as markers of the nervous tissue in Xenopus. During Xenopus oogenesis, stathmin accumulates and remains stable as a maternal product throughout early development. Concurrently, its phosphorylation is regulated from essentially unphosphorylated forms to highly phosphorylated ones in the mature egg, which are then progressively dephosphorylated again from the midblastula to the tailbud stage. Altogether, our results demonstrate the high evolutionary conservation of stathmin together with the members of its related gene family, not only at the level of their molecular structures, but also of their biochemical and biological regulation. These observations are thus further in favor of a very general and likely essential role of stathmin in the normal control of cells throughout development and in the adult.

Amino Acid Sequence↗
PubMed1990

Visual and electrosensory circuits of the diencephalon in mormyrids: an evolutionary perspective.

Mormyrids are one of two groups of teleost fishes known to have evolved electroreception, and the concomitant neuroanatomical changes have confounded the interpretation of many of their brain areas in a comparative context, e.g., the diencephalon, where different sensory systems are processed and relayed. Recently, cerebellar and retinal connections of the diencephalon in mormyrids were reported. The present study reports on the telencephalic and tectal connections, specifically in Gnathonemus petersii, as these data are critical for an accurate interpretation of diencephalic nuclei in teleosts. Injections of horseradish peroxidase into the telencephalon retrogradely labeled neurons ipsilaterally in various thalamic, preglomerular, and tuberal nuclei, the nucleus of the locus coeruleus (also contralaterally), the superior raphe, and portions of the nucleus lateralis valvulae. Telencephalic injections anterogradely labeled the dorsal preglomerular and the dorsal tegmental nuclei bilaterally. Injections into the optic tectum retrogradely labeled neurons bilaterally in the central zone of area dorsalis telencephali and ipsilaterally in the torus longitudinalis, various thalamic, pretectal, and tegmental nuclei, some nuclei in the torus semicircularis, the nucleus of the locus coeruleus, the nucleus isthmi and the superior reticular formation, basal cells in the ipsilateral valvula cerebelli, and eurydendroid cells in the contralateral lobe C4 of the corpus cerebelli. Weaker contralateral projections were also observed to arise from the ventromedial thalamus and various pretectal and tegmental nuclei, and from the locus coeruleus and superior reticular formation. Tectal injections anterogradely labeled various pretectal nuclei bilaterally, as well as ipsilaterally the dorsal preglomerular and dorsal posterior thalamic nuclei, some nuclei in the torus semicircularis, the dorsal tegmental nucleus, nucleus isthmi, and, again bilaterally, the superior reticular formation. A comparison of retinal, cerebellar, tectal, and telencephalic connections in Gnathonemus with those in nonelectrosensory teleosts reveals several points: (1) the visual area of the diencephalon is highly reduced in Gnathonemus, (2) the interconnections between the preglomerular area and telencephalon in Gnathonemus are unusually well developed compared to those in other teleosts, and (3) two of the three corpopetal diencephalic nuclei are homologues of the central and dorsal periventricular pretectum in other teleosts. The third is a subdivision of the preglomerular area, rather than an accessory optic or pretectal nucleus, and is related to electroreception. The preglomerulo-cerebellar connections in Gnathonemus are therefore interpreted as uniquely derived characters for mormyrids.

Animals↗
PubMed1991

Vertebrate craniofacial development: the relation between ontogenetic process and morphological outcome.

Many structures that are present, often transiently, in the head of extant vertebrate embryos appear to be segmentally organized. These include the brain, particularly the hindbrain (e.g., rhombomeres), and adjacent axial structures such as paraxial mesoderm (e.g., somites, somitomeres) and neural crest cells. Also present in the head are additional sets of serially arranged structures that develop in more ventral and lateral locations. Examples of these are epibranchial placodes, aortic arches, and pharyngeal pouches. All these embryonic structures are frequently used both individually and collectively as characters to assist in defining homologies. New cell labeling and identification methods are providing detailed accounts of cell movements and tissue lineages that reveal a range of disparate behaviors not previously appreciated. The well-known migrations of neural crest cells bring all but the neurogenic members of this mesenchymal population form dorsal, axial locations into ventral and rostral locations where they largely surround the pharynx, stomdeum, and prosencephalon. Equally dramatic movements of neural plate cells, myoblasts, angioblasts, and placode-derived cells have recently been documented. These movements may occur in concert with those of other nearby tissues (e.g., branchiomeric myoblasts, neural crest cells, and surface ectoderm) or may be independent (e.g., placodal neuroblasts). Migrating cells may be clustered and follow definable pathways towards their destination (e.g., neural crest cells), or they may be solitary and wander invasively without a prespecified destination (e.g., angioblasts). These extensive morphogenetic movements bring cells into contact with a greater variety of other tissues and matrix environments than has heretofore been recognized. Moreover, because of these rearrangements, the cells present in a particular location, such as a branchial arch, may trace their ancestry to many axial levels, which complicates the analyses of segmental relations. Comparative morphological studies of craniofacial development have recently been augmented by descriptions of the sites and times of expression of many matrix components, growth factors and their receptors, and regulatory genes. Particularly important has been the discovery of a network of genes called the homeobox family. These genes are similar in their sequence and their organization along a chromosome to genes that establish the spatial identity of prospective body parts in drosophila. The combination of cellular and molecular descriptive studies of vertebrate craniofacial development provide exciting opportunities to catalogue patterns of gene expression and morphogenesis during the gastrula, neurula, and early organogenesis stages. Moreover, such data form the basis for proposing and then testing hypotheses about the mechanisms controlling cell movements, tissue formation, and the assembly of functionally integrated sets of structures.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2007

Evolution of cognitive function via redeployment of brain areas.

The creative reuse of existing neural components may have played a significant role in the evolutionary development of cognition. There are obvious evolutionary advantages to such redeployment, and the data presented here confirm three important empirical predictions of this account of the development of cognition: 1) A typical brain area will be used by many cognitive functions in diverse task categories, (2) evolutionarily older brain areas will be deployed in more cognitive functions, and (3) more recent cognitive functions will use more, and more widely scattered, brain areas. These findings have implications not just for our understanding of the evolutionary origins of cognitive function but also for the practice of both clinical and experimental neuroscience.

Animals↗
PubMed1988

The structure of brain-specific rat aldolase C mRNA and the evolution of aldolase isozyme genes.

The cDNA clones for rat aldolase C mRNA having the nearly complete length were isolated from a rat brain cDNA library and sequenced. The nucleotide sequence of pRAC2-1, a cDNA clone having the largest cDNA insert, indicates that the cDNA is composed of a 105-base-pair 5'-noncoding sequence, a 1089-base-pair coding-sequence and a 382-base-pair 3'-noncoding sequence. The amino acid sequence of aldolase C deduced from a possible open reading frame was composed of 362 residues having a relative molecular mass of 39,164 excluding the initiating methionine, one amino acid shorter than aldolases A and B. The length of aldolase c mRNA was 1750 residues, somewhat longer than that of the aldolase A and B transcripts. The aldolase C mRNA was distributed mainly in the brain, some in ascites hepatoma and fetal liver. Comparison of the amino acid sequences of rat aldolase C with those for rat aldolase A and B [Joh et al. (1985) Gene 39, 17-24; Tsutsumi et al. (1984) J. Biol. Chem. 259, 14572-14575], which have been determined previously, shows the existence of highly conserved stretches of amino acid among the three isozymic forms throughout their sequences. The extent of the homology between aldolases A and C is 81%, while those between aldolases A and B, and B and C are 70%, respectively. The analysis of amino acid substitution among aldolases A, B and C from several species suggests that the isozyme genes diverged much earlier than animal species appeared and that the aldolase C gene has evolved from the aldolase A gene after aldolase A and B genes diverged.

Amino Acid Sequence↗
PubMed1978

Adult onset of the Dandy-Walker syndrome.

Two patients with the Dandy-Walker malformation first developed neurologic symptoms in adult life. In both patients there was normal motor and intellectual development during childhood, but as adults they had gradual evolution of brain stem and cerebellar signs and obstructive hydrocephalus. Following resection of the fourth ventricular cyst, both patients recovered. A review of the literature disclosed seven additional patients in whom the Dandy-Walker syndrome was first diagnosed in adult life. These cases illustrate that this congenital brain malformation may not only first become symptomatic later in life, but that it is possible for patients to remain asymptomatic.

Adult↗
PubMed1983

Hemispheric specialization and the neurology of emotion.

The regulation of such biologic drives as sex and aggression is a critical evolutionary function required of the nervous system. There is evidence that, in humans, the right hemisphere is dominant for many "emotional" functions. In the cortical regions involved in emotion, there are two important, complementary, sensorilimbic connective pathways: a dorsal system critical for surveillance, attention, and arousal and a ventral system specialized for stimulus identification, learning, and emotional response. Hemispheric specialization may introduce lateral asymmetries in these sensorilimbic connections, which could account for contrasting dominance in both emotional functions and some cognitive domains.

Affect↗
PubMed2000

Is depression an adaptation?

Many functions have been suggested for low mood or depression, including communicating a need for help, signaling yielding in a hierarchy conflict, fostering disengagement from commitments to unreachable goals, and regulating patterns of investment. A more comprehensive evolutionary explanation may emerge from attempts to identify how the characteristics of low mood increase an organism's ability to cope with the adaptive challenges characteristic of unpropitious situations in which effort to pursue a major goal will likely result in danger, loss, bodily damage, or wasted effort. In such situations, pessimism and lack of motivation may give a fitness advantage by inhibiting certain actions, especially futile or dangerous challenges to dominant figures, actions in the absence of a crucial resource or a viable plan, efforts that would damage the body, and actions that would disrupt a currently unsatisfactory major life enterprise when it might recover or the alternative is likely to be even worse. These hypotheses are consistent with considerable evidence and suggest specific tests.

Adaptation, Physiological↗
PubMed1999

Topographic organisation of extrastriate areas in the flying fox: implications for the evolution of mammalian visual cortex.

The organisation of extrastriate cortex was studied in anaesthetised flying foxes (Pteropus poliocephalus) by using multiunit recording techniques. Based on the visuotopic organisation and response characteristics, the cortex immediately rostral to the second visual area (V2) was subdivided into two fields: visual area 3 (V3) laterally and the occipitoparietal area (OP) medially. Area V3 is a 1.0-1.5 mm wide strip of cortex that represents the entire contralateral hemifield as a mirror image of the representation found in V2. The representation of the vertical meridian and the area centralis form the rostral border of V3. In area OP, receptive fields are much larger than those of V3 and form a separate visuotopic map, with the upper quadrant represented rostral to the lower quadrant. Multiunit clusters in the cortex rostral to area OP (posterior parietal area) respond to both visual and somatosensory stimuli. Farther laterally, in the cortex rostral to V3, the occipitotemporal area (OT) was found to form yet another map of the visual field. Similar to the middle temporal area in primates, area OT in the flying fox forms a first-order representation of the visual field, with the lower quadrant represented medially, the upper quadrant represented laterally, the area centralis represented caudally, and the visual field periphery represented rostrally. The cortex surrounding area OT rostrally and ventrally is also visually responsive but could not be subdivided due to the large receptive fields. Finally, visual responses were elicited from an area adjacent to the peripheral representation in the first visual area (V1) in the splenial sulcus. These results demonstrate that nearly half of the flying fox cortex is related to vision, which contrasts with that of microchiropteran bats, in which auditory areas predominate. A comparison of the flying fox with other mammals suggests that several areas, including homologues of V1, V2, V3, OT, and the splenial area, may have originated early in mammalian evolution and have been inherited by most present-day eutherians. However, studies in other species will be needed to distinguish patterns of common ancestry from parallel evolution.

Animals↗
PubMed2000

Somatosensory and motor representations in cerebral cortex of a primitive mammal (Monodelphis domestica): a window into the early evolution of sensorimotor cortex.

To examine the potential early stages in the evolution of sensorimotor cortex, electrophysiological studies were conducted in the primitive South American marsupial opossum, Monodelphis domestica. Somatosensory maps derived from multiunit microelectrode recordings revealed a complete somatosensory representation of the contralateral body surface within a large region of midrostral cortex (primary somatosensory cortex, or S1). A large proportion ( approximately 51%) of S1 was devoted to representation of the glaborous snout, mystacial vibrissae, lower jaw, and oral cavity (the rostrum). A second representation, the second somatosensory area (or S2), was found adjacent and caudolateral to S1 as a mirror image reversed along the representation of the glabrous snout. A reversal of somatotopic order and an enlargement of receptive fields marked the transition from S1 to S2. Mapping of excitable cortex was conducted by using intracortical microstimulation (ICMS) techniques, as well as low-impedance depth stimulation and bipolar surface stimulation. In all three procedures, electrical stimulation resulted in movements confined strictly to the face. Specifically, at virtually all sites from which movements could be evoked, stimulation resulted in only vibrissae movement. ICMS-evoked vibrissae movements typically occurred at sites within S1 with receptive fields of the mystacial vibrissae, lower jaw, and glaborous snout. Results were similar using low-impedance depth stimulation and bipolar surface stimulation techniques except that the motor response maps were generally larger in area. There was no evidence of a motor representation rostral to S1. Examination of the cytoarchitecture in this cortical region (reminiscent of typical mammalian somatosensory cortex) and the high levels of stimulation needed for vibrissae movement suggest that the parietal neocortex of Monodelphis is representative of a primitive sensorimotor condition. It possesses a complete S1 representation with an incomplete motor component overlapping the S1 representation of the face. It contains no primary motor representation. Completion of the motor representations within S1 (trunk, limbs, tail) as well as the emergence of a primary motor cortex rostral to S1 may have occurred relatively late in mammalian phylogeny.

Animals↗
PubMed1998

Spatial mapping takes time.

The experiment tested the prediction that spatial mapping takes time and asked whether time use is reflected in the overt behavior of a performing animal. The study examines this question by exploiting the expected behavioral differences of control rats and rats with hippocampal formation damage induced with fimbria-fornix (FF) lesions on a spatial navigation task. Previous studies have shown that control rats use a mapping strategy, in which they use the relative positions of environmental cues to reach places in space, whereas FF rats use a cue-based strategy, in which they are guided by a single cue or their own body orientation. Therefore, control and FF rats were overtrained on a complex foraging task in which they left a burrow to retrieve eight food pellets hidden around the perimeter of a circular table. The control rats retrieved the food pellets in order of their distance from the burrow, took direct routes to the food, and made few errors, all of which suggested they used a spatial strategy. The FF rats were less likely to retrieve food as a function of its distance, took a circular path around the perimeter of the table, and made many errors, suggesting they used a cue-based strategy. Despite taking shorter routes than the FF rats, the control rats had proportionally slower response speeds. Their slow response speeds support the hypothesis that spatial mapping takes time and that mapping time is reflected in behavior. The results are discussed in relation to their relevance to spatial mapping theory, hippocampal function, and the evolution of foraging strategies.

Animal Feed↗
PubMed2000

Oligodendrocyte lineage and the motor neuron connection.

One of the more surprising recent discoveries in glial biology has been that oligodendrocytes (OLs) originate from very restricted regions of the embryonic neural tube. This was surprising because myelinating OLs are widespread in the mature central nervous system, so there was no reason to suspect that their precursors should be restricted. What we now know about early OL development suggests that they might have as much (or more) in common with ventral neurons-specifically motor neurons (MNs)-as with other types of glia. This has implications for the way we think about glial development, function, and evolution. In this article we review the evidence for a shared MN-OL lineage and debate whether this is the only lineage that generates OLs. We decide in favour of a single embryonic lineage with regional variations along the anterior-posterior neuraxis.

Animals↗
PubMed2000

Natural selection, mental modules and intelligence.

The question of whether intelligence is one trait or many has exercised several generations of researchers, but no consensus is in sight. Evolutionary psychology, with its emphasis on domain-specific mental modules, seems to offer hope for advancing understanding of this question. We know that the mind has been shaped by natural selection to maximize reproductive success. This tells us what the mind must do--it must solve the adaptive problems that the organism confronts. However, whether this functional capacity is manifest in congruent anatomic, physiological, genetic, cognitive or psychometric structures is another matter. Examination of how natural selection shaped other mechanisms suggests that knowing functional demands provides only modest guidance as to the structure of mechanisms. None the less, it remains simultaneously clear that these mechanisms are not entirely general, but have been shaped to cope with specific challenges. Our metaphors for the mind, whether as a digital computer or a Swiss army knife, are misleading because computers and tools are products of intelligent design. In contrast, minds are products of natural selection whose intertwined components are products of incorporated genetic mutations whose effects are widespread and constrained by historical precedents. Our tendencies to describe the structure of the mind in terms of discrete components make it difficult for us to comprehend the mind as a mind. One antidote may be to minimize metaphorical descriptions of postulated structures of mind and focus instead on its function.

Animals↗