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PubMed1988

Medullary and mesencephalic pathways and connections of lateral line neurons of the spiny dogfish Squalus acanthias.

The neuronal connections of the electrosensory dorsal and the mechanosensory medial octavolateralis nuclei of the spiny dogfish Squalus acanthias were studied by horseradish peroxidase, autoradiographic and axonal degeneration methods. Efferents from each nucleus, in addition to extensive commissural components, give rise to ipsilateral and contralateral lemnisci that ascend to midbrain levels and terminate among the cells of the lateral mesencephalic nucleus (LMN). Within LMN, electrosensory and mechanosensory neurons distribute dorsolateral and ventromedial in position, respectively. Ascending fibers of both modalities also terminate within the central zone of the optic tectum. The LMN of spiny dogfish sharks that possess a primitive pattern of midbrain organization is homologous to parts of the lateral mesencephalic nuclear complex of batoids that possess a more derived pattern of midbrain organization. Other fiber connections of the dorsal and medial octavolateralis nuclei appear to differ from each other, indicating that electrosensory and mechanosensory lateral line information is carried over separate pathways at least to midbrain levels of the brain stem. For example, nucleus B, a feedback center, occupies a position in the descending lateral line pathways of sharks and skates similar to nucleus praeeminentialis of many electrosensory teleosts. The dorsal octavolateralis nucleus of sharks and skates receives afferents from nucleus B but there is no evidence that nucleus B directly feeds back to the medial octavolateralis nucleus of the spiny dogfish. Moreover, unlike the dorsal nucleus, the medial nucleus of Squalus is reciprocally linked with the octaval system.

Animals↗
PubMed1995

Cloning and regional assignment of the human myosin heavy chain 12 (MYH12) gene to chromosome band 15q21.

Sequences encoding 1,235 bp of the human myosin heavy chain 12 (MYH12) gene have been cloned from a human brain cDNA library by PCR amplification. The human sequence is 95.8% identical to the mouse sequence at the amino acid level, indicating that the MYH12 gene has been evolutionarily well conserved. Somatic cell hybrid analysis and in situ hybridization place the MYH12 gene on human chromosome 15, at band q21, and extend distally the known region of chromosome 15 linkage homology on mouse chromosome 9.

Amino Acid Sequence↗
PubMed1984

Pain perception and alleviation in animals.

In the last 2 decades there have been substantial advances in our knowledge of the scientific basis of the mechanisms of pain. Nociceptors or pain receptors are widespread in the skin and tissues of animals; chemical mediation of nociceptor excitation may provide a key for understanding the peripheral phenomena related to pain. The expression of pain in animals involves multiple ascending and descending branches, as well as specialized pain-signaling mechanisms in the spinal cord. The importance of these different pathways varies with species and circumstances. Endogenous neural systems in the brain stem and forebrain including both opioid and nonopioid mechanisms may modulate the central transmission of nociceptive signals in animals. Noxious stimuli mediate a variety of different functions; each animal has a consistent response to noxious stimuli or a consistent pattern of escape from pain. As we better understand the mechanisms of pain, the humane treatment and alleviation of pain in experimental animals can be placed on a much firmer scientific basis.

Afferent Pathways↗
PubMed1995

The distribution of GAP-43 immunoreactivity in the central nervous system of adult opossums (Didelphis virginiana) with notes on their development.

The distribution of the growth associated protein GAP-43 has been described in the brain and spinal cord of rats and other placental mammals but not marsupials. In order to provide such information, we employed a monoclonal antibody to immunostain for GAP-43 in the central nervous system of adult and developing opossums, Didelphis virginiana. The GAP-43 immunoreactivity was widely distributed in the brain of adult opossums, but it was particularly dense within specific layers of the olfactory bulb and hippocampal formation, layer I of the cerebral cortex, the bed nucleus of the stria terminalis, the nucleus accumbens, the striatum, the amygdala, the septum, the olfactory tubercle, medial parts of the preoptic area and diencephalon, the substantia nigra, the ventral tegmental area, the periaqueductal grey matter, the interpeduncular nucleus, the periventricular grey, the molecular layer of the cerebellum, the superior central nucleus, the basilar pons, the dorsal vagal and solitary nuclei, and laminae I and II of the spinal trigeminal nucleus. Immunoreactivity for GAP-43 was also present within the spinal cord, where it was densest within laminae I, II, IX, and X and within the intermediolateral cell column. In most areas of the brain and some areas of the spinal cord, an inverse correlation existed between the location of GAP-43 and myelin. Immunostaining for GAP-43 was found throughout most of the central nervous system during early development, but it decreased with age in a regionally specific manner until the adult pattern was reached. Our results suggest that the distribution of GAP-43 in opossums is similar in many respects to that reported in rats and that it is developmentally regulated.

Age Factors↗
PubMedDate not supplied

[The role of an evolutionary approach to the study of the structure and function of gangliosides].

A comparative-biochemical study of gangliosides is an effective approach to understanding their structural diversity and functions. Certain new gangliosides which are essential in processes occurring in the nerve and other tissues of vertebrates (tetra- and pentasyalogangliosides, trisyalogangliosides with a short carbon chain and others) were first found when investigating fish and amphibia brain and then in the mammalian nerve tissue. Comparative studies made it possible to characterize a new aspect of the functional role of gangliosides, their adaptation functions. Investigations in the content and composition of gangliosides in representatives of different taxonomic groups of animals are important for a more profound understanding of other functions of these compounds, their role in the processes of the nerve impulse transmission, intercellular interaction, etc. Comparative-immunochemical studies of gangliosides seem to be also promising and timely.

Adaptation, Physiological↗
PubMed2005

Quantitative magnetization transfer by trains of radio frequency pulses in human brain: extension of a free evolution model to continuous-wave-like conditions.

A theoretical model of free evolution between repeated magnetic transfer (MT) pulses was extended to continuous-wave (CW)-like conditions showing that only the repetitive "direct" saturation of bulk water changes the transient and stationary behavior. The influence of the pulse repetition period (PR) on progressive saturation was studied in cortical gray matter (GM) and central white matter (WM) under conditions of short periods of free evolution and strong macromolecular saturation. Interpulse delays of 3 ms were achieved in vivo on a 1.5-T MR system with bell-shaped MT pulses of 12-ms duration and nominal flip angles of up to 1440 degrees and single-shot readout by a stimulated echo acquisition mode localization sequence. The frequency offset was chosen between 1 and 3 kHz to avoid excessive direct saturation. The stationary MT ratio (MTR) followed an inverse linear PR dependence, showing a consistent partial saturation of about 90% at zero PR for both WM and GM. Comparison to a relaxation-matched liquid indicated the presence of MT, but not necessarily of direct saturation. The transient behavior indicated considerable direct saturation, but this could also be explained by MT. These inconsistencies showed that the intervals of time evolution in our experiments were too long to be modeled by CW-like conditions. Free evolution takes place during the whole PR rather than during the interpulse delay only. Quantification using the rates of free evolution theory yielded the saturations and rate constants necessary to explain the observed behavior. The theory of rapid CW-like pulsing provides an upper limit for the rate of progressive saturation. This limit is approached at PR below an estimated value of 5 ms. The phenomenological PR dependence of the steady-state MTR may indicate that MT exceeded the direct saturation. Unlike to an idealized CW experiment, the extrapolated value at zero PR is subject to direct effects and not a physically meaningful constant.

Adult↗
PubMed1989

[Language and reality: the origin of man].

The author proposes: 1. That a lineage of living systems is constituted by the reproductive conservation of a manner of living under the form of an ontogenic phenotype. 2. That language is a manner of living in recurrent consensual coordinations of consensual coordinations of actions. 3. That the human manner of living entails among other things, a braiding of languaging and emotioning that we call conversation. 4. That human beings arise in the history of bipedal primates with the origin of language, and the constitution of a lineage defined by the conservation of an ontogenic phenotype that includes conversations as part of it. 5. That the magnitude of the involvement of the brain and anatomy of the larynx and face in speech as our main manner of languaging indicate that language cannot have arisen later than two to three millions year ago. 6. That rationally pertains to the operational coherences of languaging and that different rational domains are constituted by different basic notions that are accepted a priori. That is, on preference. 7. That responsibility and freedom are a function of our awareness of the participation of our emotions (preferences) in the constitution of the rational domains in which we operate.

Biological Evolution↗
PubMed1993

Origin of JC polyomavirus variants associated with progressive multifocal leukoencephalopathy.

JC polyomavirus (JCV) DNAs from the urine of nonimmunocompromised individuals (designated archetypal isolates) regularly contain a regulatory sequence that may have generated various regulatory sequences of JCV isolates derived from the brain of patients with progressive multifocal leukoencephalopathy (PML). In this report, we constructed a phylogenetic tree for 14 isolates (7 archetypes and 7 PML types) from DNA sequence data on the VP1 (major capsid protein) gene. According to the phylogenetic tree, the 14 isolates diverged into types A and B, each of which contained archetypal and PML-type isolates. Each type further diverged into several groups containing archetypal and PML-type isolates. We conclude that PML-type isolates are polyphyletic in their origin and do not constitute a unique lineage. This conclusion suggests that PML-type JCV isolates are generated from archetypal strains during persistence in the hosts. Furthermore, the present phylogenetic analysis indicates that an ancestral JCV carried the archetypal regulatory sequence and that this structure has been conserved in the course of JCV evolution.

Base Sequence↗
PubMed1993

Isolation and characterization of the human melanin-concentrating hormone gene and a variant gene.

Melanin-concentrating hormone (MCH) is a cyclic peptide found expressed almost exclusively in the hypothalamus while MCH-containing fibers project throughout the brain of many vertebrates including man. In fishes, MCH induces melanin concentration within the melanophores and may inhibit ACTH secretion. In mammals, MCH modulates ACTH release in vivo and participates as a neuromediator in the control of complex behaviors such as water and food intake. Salmon, rat and human MCH cDNAs have been cloned and structures of deduced mRNAs and precursors have been elucidated. In this report we determine the nucleotide sequence of two human MCH (hMCH) genes and demonstrate that both genes are expressed in human brain. Cloning from three genomic libraries and sequencing of one class of hMCH genomic DNA reveal high similarity between coding regions and the C-terminal part of the hMCH prohormone. However no sequence identity was found in the N-terminal and 5' end non-coding regions of the gene between them even within 6.5 kilobases (kb) upstream from the truncation point. Using polymerase chain reaction (PCR) analysis we have identified RNA populations that are derived from this gene in human brain. For that reason, this gene is a variant rather than a pseudogene. The authentic hMCH gene could only be cloned by using the PCR technique. With primers specific to 5'-end and 3'-end regions of the MCH mRNA we amplified a 1400 bp fragment as well as other shorter PCR products from human genomic DNA. The longest PCR fragment contains 3 exons encompassing most of the 5' untranslated and all of the coding and 3' untranslated sequences of the hMCH mRNA, that are separated by two introns of 350 and 271 bp, respectively. Interestingly the second intron dissects the hMCH peptide sequence in both the authentic and the variant gene. A strikingly high degree of homology was found between the variant and authentic hMCH genes, including intronic sequences, suggesting that these two genomic sequences diverged very recently during evolution. A strong homology was also noted between the exons and intervening sequences of the human and rat MCH genes. Altogether, our results provide the first strong evidence for the existence of two distinct MCH genes expressing prohormones with different MCH and neuropeptide EI (NEI) sequences in human and along with in vivo and in vitro findings, suggest that these neuropeptides may influence the activity of numerous mammalian neuronal systems.

Amino Acid Sequence↗
PubMed1980

The parcellation theory and its relation to interspecific variability in brain organization, evolutionary and ontogenetic development, and neuronal plasticity.

Recently discovered neocortical equivalents in anamniotes and certain patterns of interspecific variability in brain organization provide new insights into evolutionary and ontogenetic mechanisms of development. The new data suggest that nervous systems become more complex, not by one system invading another, but by a process of parcellation that involves the selective loss of connections of the newly formed daughter aggregates and subsystems. The parcellation process is reflected in the normal ontogenetic development of the CNS in a given species and can be manipulated, to a certain extent, by deprivation or surgically induced sprouting. The parcellation theory allows certain predictions about the range of variation of a given system at all levels of analysis including the cellular and aggregate levels. For example, the interspecific variability in organization of cortical columns, thalamic nuclei, cortical areas and tectal layers can be explained. The findings, summarized here, suggest that diffuse, undifferentiated systems existed in the beginning of vertebrate evolution and that during the evolution of complex behaviors, and analytical capacities related to these behaviors, a range of patterns of neural systems evolved that relate to these functions. One principle underlying the growth, differentiation and multiplication of neural systems appears to be the process of parcellation as defined by the theory.

Amphibians↗
PubMed1992

An inside-out theory of attention.

The brain has two attentional systems; one attentional system is devoted to intrapersonal space and the second attentional system to extrapersonal space. The development of these two attentional systems with inward or outward focus arose from the hemispheral neural systems designed for attending to extrapersonal contralateral space. As a necessary consequence of the brain changes to develop language, one of the hemispheral attentional systems was altered for intrapersonal attention while the other hemispheral attentional system became obligated to attend to all of extrapersonal space. This conceptualization of attention provides a coherent explanation for the confusing hemispheral dominance proposed for attention on the basis of clinical hemineglect, i.e. that the left hemisphere attends to right extrapersonal space and that the right hemisphere attends to both left and right extrapersonal space. This conceptualization also provides a meaningful account of denial of limbs (anosognosia) and imagery.

Animals↗
PubMed2006

Comparative mapping of serotonin-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

The serotonergic systems in nudibranch molluscs were compared by mapping the locations of serotonin-immunoreactive (5-HT-ir) neurons in 11 species representing all four suborders of the nudibranch clade: Dendronotoidea (Tritonia diomedea, Tochuina tetraquetra, Dendronotus iris, Dendronotus frondosus, and Melibe leonina), Aeolidoidea (Hermissenda crassicornis and Flabellina trophina), Arminoidea (Dirona albolineata, Janolus fuscus, and Armina californica), and Doridoidea (Triopha catalinae). A nomenclature is proposed to standardize reports of cell location in species with differing brain morphologies. Certain patterns of 5-HT immunoreactivity were found to be consistent for all species, such as the presence of 5-HT-ir neurons in the pedal and cerebral ganglia. Also, particular clusters of 5-HT-ir neurons in the anterior and posterior regions of the dorsal surface of the cerebral ganglion were always present. However, there were interspecies differences in the number of 5-HT-ir neurons in each cluster, and some clusters even exhibited strong intraspecies variability that was only weakly correlated with brain size. Phylogenetic analysis suggests that the presence of particular classes of 5-HT-ir neurons exhibits a great deal of homoplasy. The conserved features of the nudibranch serotonergic system presumably represent the shared ancestral structure, whereas the derived characters suggest substantial independent evolutionary changes in the number and presence of serotonergic neurons. Although a number of studies have demonstrated phylogenetic variability of peptidergic systems, this study suggests that serotonergic systems may also exhibit a high degree of homoplasy in some groups of organisms.

Animals↗
PubMed2006

Evolutionary background for stress-coping styles: relationships between physiological, behavioral, and cognitive traits in non-mammalian vertebrates.

Reactions to stress vary between individuals, and physiological and behavioral responses tend to be associated in distinct suites of correlated traits, often termed stress-coping styles. In mammals, individuals exhibiting divergent stress-coping styles also appear to exhibit intrinsic differences in cognitive processing. A connection between physiology, behavior, and cognition was also recently demonstrated in strains of rainbow trout (Oncorhynchus mykiss) selected for consistently high or low cortisol responses to stress. The low-responsive (LR) strain display longer retention of a conditioned response, and tend to show proactive behaviors such as enhanced aggression, social dominance, and rapid resumption of feed intake after stress. Differences in brain monoamine neurochemistry have also been reported in these lines. In comparative studies, experiments with the lizard Anolis carolinensis reveal connections between monoaminergic activity in limbic structures, proactive behavior in novel environments, and the establishment of social status via agonistic behavior. Together these observations suggest that within-species diversity of physiological, behavioral and cognitive correlates of stress responsiveness is maintained by natural selection throughout the vertebrate sub-phylum.

Adaptation, Psychological↗
PubMed1994

Projection of brain stem neurons to the giant electromotoneurons in the cervical spinal cord of the electric catfish Malapterurus electricus.

Two giant electromotoneurons located within the cervical spinal cord form the centerpiece of the electromotor system in the electric catfish Malapterurus electricus. The cytoarchitectural organization suggests a high degree of input convergence onto the electromotoneurons. In order to obtain insights into the connectivities of the electromotor system, pre-neurons of the electromotoneurons within the brain stem and the spinal cord were labelled by application of FITC-dextran and horseradish peroxidase onto the surface of a single electromotoneuron. Our results show that the electromotoneurons receive their main inputs from the nucleus profundus mesencephali within the tegmentum and from large neurons of the medial reticular formation. Both nuclei possess an intimate connection to the optic tectum which mediates orientation responses. This pathway to the electromotoneurons could be instrumental in eliciting electric organ discharge during prey catching. The electric avoidance response in turn could be mediated by the Mauthner neurons which are also labelled. In addition to these neurons, cells of the nucleus fasciculi longitudinalis medialis, the descending octaval nucleus and the nucleus funicularis medialis were labelled. As compared to the corresponding neurons in ictalurid catfish, none of these neurons displays any alteration in its general morphology. It is concluded that the evolution of the electric organ from muscle tissue and the development of a central control system of the electromotor response in Malapterurus involved a minimum of alterations in central nervous system circuitry. In contrast to many other electric fishes the electromotor control is mainly accomplished at the level of the electromotoneurons.

Animals↗
PubMed2002

How do features of sensory representations develop?

Sensory representations in the brainstem and cortex have a number of features that support the idea that neural activity patterns are important in their development. Many of these features vary across species in ways that could result from perturbances in the balance of the effects of activity patterns and position-dependent gene expression. (1) Most notably, disruptions or septa in sensory maps often reflect actual discontinuities in the receptor sheet, and the discontinuities may be reflected in a series of interconnected maps. Species with different disruption patterns in sensory sheets have different matching disruption patterns in the sensory maps and variant individuals and strains of the same species have matching variations in the receptor disruption patterns and their sensory maps. (2) In addition, mutations that misdirect some of the retinal afferents from one side of the brain to the other create new sensory maps that preserve continuities in the altered pattern of input, while creating new structural discontinuities. (3) Furthermore, functionally different classes of afferents that are mixed in the receptor sheet often segregate to activate separate populations of target cells. (4) Finally, early developing portions of receptor sheets may gain more than their share of territory in sensory maps. These and other variable features of sensory maps are most readily accommodated by theories that involve roles for instruction by evoked and spontaneous neural activity patterns.

Animals↗
PubMed1990

[Quantitative analysis of the teleost brain: evolutionary and adaptive features of encephalization. II. Primary brain subdivisions].

1. Frequently there is an opposition between olfactory and visual senses. Fresh water fishes are generally macrosomatic and microptic, marine fishes (especially coral reef fishes) are microsmatic and macroptic while piscivorous pelagic fishes are macrosmatic and macroptic. 2. The importance of the cerebellum is a function of both the fish's activity level and its body size. 3. There is a marked opposition between the diencephalon and the medulla oblongata and a greater one between the non-olfactory-telencephalon (NOT) and the medulla oblongata (MA). Although it is not possible to give an accurate evolutionary significance, the ratio of NOT/MA is low in primitive teleostean fishes and high in more derived species (Acanthuridae and Tetraodontiformes).

Animals↗
PubMed1994

Distribution of tyrosine hydroxylase immunoreactivity in the brain of Typhlonectes compressicauda (Amphibia, Gymnophiona): further assessment of primitive and derived traits of amphibian catecholamine systems.

Until now, catecholamine systems are well studied in the brains of anurans and urodeles, but such data are almost completely lacking for the third order of amphibians, i.e. the limbless Gymnophiona or Apoda. To further assess general and derived features of the catecholamine systems in this class of vertebrates, the distribution of tyrosine hydroxylase immunoreactive (THi) cell bodies and fibers was studied in the brain of the gymnophionan Typhlonectes compressicauda. The distribution of THi cell groups in the brain of gymnophionans largely resembles that found in anurans and urodeles. However, in gymnophionans additional THi cells were found in the reticular formation and in the prevagal part of the solitary tract nucleus. Other differences with anurans and urodeles concern the relatively larger number of THi cells in the midbrain tegmentum and in the hypothalamus, where the cells are mainly of the liquor-contacting type. The distribution of THi fibers in some brain regions of gymnophionans, e.g. pallial and basal forebrain areas, shows a greater resemblance with that of urodeles than with that of anurans. A peculiar feature of Typhlonectes are the pericellular baskets of THi varicosities in the lateral septal region. Such baskets were never observed in other amphibians, but do occur in the septal region of amniotes. Finally, the data obtained in this study support the suggestion that catecholamines play a role in the processing of sensory modalities such as olfactory, visual, auditory, vestibular, and mechanoreceptive lateral line information, but not in electroreception.

Amphibians↗