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PubMed1995

Manatee cerebral cortex: cytoarchitecture of the caudal region in Trichechus manatus latirostris.

In several brains of the Florida manatee, Trichechus manatus latirostris, the architecture of caudal regions of cerebral cortex was examined in order to complete a map of cortical areas in the brain of this unique herbivore. Through observation of sections stained for Nissl substance, myelinated axons, acetylcholinesterase and cytochrome oxidase, we have identified 11 new cortical areas based on qualitative cytoarchitectural appearance and measurements of laminar thicknesses, for a total of 24 such cortical areas in manatee cerebral cortex. Some areas exhibit poorly differentiated laminae while in others there are 6 clearly demarcated layers, often with sublaminar organization. Some previously identified areas were found to extend into the region caudal to the vertically oriented lateral fissure. As in other mammalian brains, cortical areas in manatees are organized in concentric rings of allocortex, mesocortex, and isocortex. Putative functional roles have been assigned to most of the identified areas based on location, architecture, behavioral and anatomical considerations, and extrapolation from other taxa in which functional mapping has been done.

Animals↗

PubMed1985

Application of molecular biology to mental illness. Analysis of genomic DNA and brain mRNA.

Techniques in molecular biology and genetics have made it possible to systematically study gene effects in human disease. The number of gene clusters specifically encoding human brain structure and function is probably about 1,600 or half of all clusters. Evolutionary effects such as linkage disequilibrium and conservation of exons (DNA encoding structural proteins) as well as the fact that there are a tractable number of gene clusters involved, tend to make it quite likely that DNA pathology or DNA variation (polymorphism) predisposing to mental illness can be detected. Genes involved in mental illness can be detected either by studying DNA obtained from blood samples (genomic DNA) directly or by the analysis of mRNA and proteins from suitable cell or tissue preparations. The study of gene expression in the human brain is still in its infancy, nevertheless there are some hints that non-poly-adenylated mRNAs may be important in brain development and certain transcribed sequences may have a specific role in gene expression of the brain. The advantage of studying genomic DNA by the use of linkage and association analysis in multiply affected families is that it will, in the end, almost certainly yield a positive result for a disease with a substantial genetic input. Analysis of gene products from tissues such as brain could in theory detect specific disease genes but the approach will also identify genes secondarily affected by the disease process. Differentiation of genes that are primarily causing mental illness from those that are secondarily affected can be carried out by using such candidate genes as linkage markers in multiply affected families.

Animals↗

PubMed1986

[Encephalization of the marine lamprey, Petromyzon marinus (L.). Quantitative analysis of the principle brain subdivisions].

The measure of both the somatic weight (S) and the brain weight (E) on a sample of 13 adult individuals of Petromyzon marinus (L.) leads for this species to the determination of its brain-body weight coefficient of allometry and to the knowledge of its index of encephalization. The value of the first one is 0.556. Its locates the Sea-Lamprey at the highest level of a scale of decreasing values belonging one after the other to Chondrichthyes (0.551), to Teleost fishes (0.487), to Anurans (0.458), to Reptiles (0.43) and at last to Mammals (0.25). This result revalues our previous hypothesis which gives to this kind of statistic a phylogenetic meaning (RIDET et al. 1977). The index of encephalization has been arbitrarily fixed at the 10 value; it is the lowest of all the other indices previously known and consequently it points the Sea-Lamprey as the less encephalized Vertebrate species. The histological study carried out on the brain allows to the knowledge of the volumes of the main encephalic subdivisions. It leads to various results as: 1. The study the relative volumes (that is to say the volume of each subdivision expressed in percentage of the volume of the whole brain) emphasizes the olfactory bulbs and the Tegmentum + Medulla oblongata which have together the highest values amongst the brain percentages of Petromyzon marinus (and also of Lampetra planeri). This peculiarity has no equivalence in the brain structure of the other studied species of Vertebrates and we consider it as the expression of a primitive brain pattern. 2. The isoponderal indices locate also the Sea-Lamprey at the lowest level for all its encephalic subdivisions, as it was previously the case for the whole brain expressed by the index of encephalization. Such an unanimity seems also to be related to a fundamental brain organization. Comparisons between Petromyzon marinus, Lampetra planeri and Myxine glutinosa corroborate the paraphyletic status of the last one in the Agnathes. The differences pointed also between the two first species are less obvious but justify meanwhile a more detailed study of this group (Petromyzontidae) which shall be given soon.

Animals↗

PubMed1987

Structural and functional studies on insulin receptors from alligator brain and liver.

Insulin receptors are present in membranes prepared from Alligator mississippiensis brain and liver. The apparent molecular weight (MW) of the alpha subunits are 132 kDa and 118 kDa in liver and brain respectively. Apparent MW of the beta subunit is 92 kDa in both brain and liver receptors. Despite the structural differences between brain and liver alpha subunits, brain insulin receptors demonstrate the normal coupling between alpha and beta subunits, i.e. following binding of insulin to the alpha subunit the beta subunit undergoes autophophorylation and stimulates tyrosine specific phosphorylation of exogenously added substrates. These findings suggest that functional insulin receptors are evolutionarily well conserved.

Alligators and Crocodiles↗

PubMed1993

Evidence of decrease in brain size in ranch mink, Mustela vison f. dom., during subadult postnatal ontogenesis.

Total brain size and the volume of several brain parts were compared in male and female ranch mink of varying age and body size in an attempt to quantify postnatal maturation and growth processes in this altricial species. Volumes of fresh whole brains and of different brain parts were calculated from prepared histological sections from juvenile (2- to 3-month-old), subadult (5-month-old), and adult (older than 7 months) individuals. Allometrical calculations were performed on the basis of body weight. Changes in size of different parts of the brain obtained to different degrees were found to be dependent on age but independent of body size. From the juvenile stage to the subadult stage, total brain size remains unchanged, although most major brain parts increase in size, while the grey matter of the isocortex decreases. During subsequent development from subadult to adult, total brain size evidently decreases. Within the brain all major structures also decrease in size, except for the medulla oblongata and the mesencephalon, which remains relatively stable in size. The grey matter of the isocortex shows the greatest decrease, followed by the allocortex and corpus striatum, the cerebellum, the white matter of the isocortex, and the diencephalon. Thus, an unusual but evident 'overshoot' in size of the total brain and certain parts apparently occurs in this species before adulthood is reached. This phenomenon is discussed in connection with size changes concomitant with domestication as well as with cageing of individuals and with postnatal and seasonal size changes known from some soricid species as the so-called Dehnel phenomenon.

Age Factors↗

PubMedDate not supplied

Melatonin in the nemertine worm Lineus lacteus: identification and daily variations.

Melatonin, a well-known pineal substance implicated in conveying photoperiodic information in vertebrates, appears to be present as well in the eyes and brain of the nemertine worm: Lineus lacteus. The nyctohemeral rhythm was studied, too. The identification of melatonin in this new invertebrate species corroborates our hypothesis that it may be an evolutionarily conserved molecule, principally involved in the temporal transduction of photoperiodic information in all living organisms.

Animals↗

PubMedDate not supplied

[Association of risk factors for cerebral atherosclerosis in patients with acute ischemic brain disease].

Atherosclerosis is the primary disease in the majority of patients with ischemic brain disease (IBD). Etiopathogenesis of atherosclerosis has not been more precisely defined, but risk factors significant for its generation and development, so as for IBD development, have been identified. They were designated as risk factors for brain atherosclerosis (RFBA). The aim of this study was to establish the frequency and significance of RFBA association in the patients with acute IBD in relation to IBD severity. The investigation included 60 patients with AIBD. RFBA were: arterial hypertension, dyslipoproteinemia, diabetes and smoking. For all the patients included in the study detailed history was noted, daily glycemia profile was done, blood pressure was measured 3 times a day and parameters of lipid status with counting of LDL/HDL indices and Apo A1/Apo B were determined. IBD was confirmed by computerized tomography of brain. The degree of IBD severity was determined in all the patients by Grotta's scale. After the statistical processing, the results of the research showed that in the patients with IBD the most frequent were arterial hypertension, then smoking, dyslipoproteinemia and diabetes. In significant number of patients existed association of several factors, which was in significant positive correlation with the degree of IBD severity. It was concluded that risk factors for atherosclerosis were simultaneously risk factors for IBD. IBD is the most severe, final stage in evolution of brain atherosclerosis.

Acute Disease↗

PubMed1999

The biological affects: a typology.

This typology of biological affects is based on developmental-interactionist theory of motivation, emotion, and cognition. Affects--subjectively experienced feelings and desires--involve interoceptive perceptual systems based on primordial molecules that characterize neurochemicals. Biological affects involve primary motivational-emotional systems (primes) associated with hierarchically organized neurochemical systems in the brain, including subcortical (reptilian) and paleocortical (limbic) brain structures. Affects fulfill individualistic (selfish) functions (arousal, approach-avoidance, agonistic) and prosocial (cooperative) functions. Selfish and cooperative functions are associated respectively with the right and left hemispheres. Biological affects constitute the physiological bases for higher level affects: social affects (e.g., pride, guilt, shame, pity, jealousy), cognitive affects (e.g., curiosity, surprise), and moral affects.

Animals↗

PubMed1998

Melanin-concentrating hormone system in the brain of the lungfish Protopterus annectens.

The neurochemical anatomy of the lungfish brain is of particular interest, because many features in these animals might be representative of the common ancestor of land vertebrates. In the present study, we have investigated the localization and biochemical characteristics of melanin-concentrating hormone (MCH)-immunoreactive material in the central nervous system of the African lungfish, Protopterus annectens. The most prominent group of MCH-immunoreactive cell bodies was found in the dorsal hypothalamus. Additional groups of MCH-immunoreactive perikarya were detected in the telencephalon within the medial and dorsal pallium, the medial subpallium, and the ventral part of the lateral subpallium. Brightly immunofluorescent nerve fibers were seen in the anterior olfactory nucleus, the ventral part of the medial pallium, the medial subpallium, and the anterior preoptic area. In the diencephalon, the hypothalamus and the medial region of the dorsal thalamus exhibited a dense accumulation of fibers. MCH-immunoreactive fibers were also found in the tectum and the tegmentum of the mesencephalon and within the reticular formation of the rhombencephalon. In the pituitary, several small groups of cells of the intermediate lobe showed a bright fluorescence. Reversed-phase high-performance liquid chromatography (HPLC) analysis of diencephalon and pituitary extracts resolved a major MCH-immunoreactive peak that coeluted with synthetic salmon MCH. The distribution of MCH in the brain of P. annectens suggests that, in lungfishes, this peptide may exert neuromodulator or neurotransmitter functions. The presence of MCH-like immunoreactivity in the intermediate lobe of the pituitary indicates that, in dipnoans, MCH may also act as a typical pituitary hormone.

Animals↗

PubMed1985

Direction-selective single units in the nucleus lentiformis mesencephali of the pigeon (Columba livia).

The receptive field properties of single units within the nucleus lentiformis mesencephali (LM) of the pigeon were studied using electrophysiological methods. Previous studies have suggested that the avian LM may be homologous to the nucleus of the optic tract (NOT) in mammals. Single units in the pigeon LM are similar to mammalian NOT units in that they are direction-selective, mostly for horizontal directions, velocity-selective, have large visual receptive fields and respond preferentially to large stimuli with many visual contrasts. In contrast to most reports of NOT units of mammals, more than half of pigeon LM units prefer high velocities (greater than 10 degrees/s), a large proportion (0.37) prefer non-horizontal directions, and receptive fields that are retinotopically arranged within the LM. The response properties of pigeon LM units are compared to the response properties of units within the accessory optic nucleus (the nucleus of the basal optic root or nBOR). In the avian brain, nBOR neurons respond at low velocities (0.5-5 degrees/s) and respond predominantly to vertical stimulus movement whereas LM units respond over a broader range of velocities (0.2-80 degrees/s) and respond predominantly to horizontal movements. Thus, the LM and nBOR may play different roles in the control of compensatory eye movements.

Animals↗

PubMed2005

Evolutionary approaches to understanding sleep.

A major controversy over REM sleep's role in memory processing may owe to inadequate allowances for the highly conservative nature of evolutionary adaptations. The controversy hinges on whether NREM sleep, alone, retains primitive memory processing capabilities. The selective pressure for primitive sleep, is thought to have been the need to obviate conflicts between enormous neural processing requirements of complex visual analysis and split-second control of movements, on the one hand, and memory processing, on the other. The most efficient memory processing during mammalian and avian sleep appears to be a two-step process: synapses in individual component circuits of events are reinforced primarily by slow brain waves during NREM sleep, with the reinforced components temporally bound by fast waves, and manifested as dreams, during REM sleep. This dual action could account for partitioning of sleep periods into multiple NREM-REM cycles. It is proposed that in the absence of REM sleep, all needed memory processing can be accomplished by NREM sleep, alone, though less efficiently. Many symptoms of fatal familial insomnia are attributed to subnormal nightly reinforcement of brain circuitry because of almost total loss of sleep, and compensatory responses thereto during waking. During this disorder, sensory circuitry seemingly is spared by virtue of its supernormal reinforcement during almost continuous waking. Contrariwise, sparing of an adult's 'higher faculties' in encephalitis lethargica appears to owe to supernormal circuit reinforcement during almost continuous sleep.

Awareness↗

PubMed1985

Alterations of the eicosanoid synthetic capacity of rat brain microvessels following ischemia: relevance to ischemic brain edema.

To know the mechanism underlying ischemic brain edema, a time-course analysis of the eicosanoid synthetic capacity of brain microvessels was carried out using unilateral, middle cerebral artery (MCA)-occluded rats. Concomitant with the development of brain edema the synthetic capacity of all products, including cyclooxygenase and lipoxygenase products, increased significantly. Next the effects of 15-hydroperoxyarachidonic acid (15-HPAA) on the synthetic capacity of microvessels were examined. The drug caused a generalized increase of each product, the profile of which was similar to that obtained with ischemic hemispheres, although the ratios of each product differed somewhat among them. The enhanced synthesis of eicosanoids by 15-HPAA was markedly suppressed by radical scavengers such as alpha-tocopherol, hydroquinone, and 1,2-bis(nicotineamide)-propane. Furthermore, the evolution of brain edema was virtually suppressed by the systemic administration of 1,2-bis(nicotineamide)-propane. The above result suggests that the enzyme activity of the arachidonic acid (AA) cascade of microvessels is stimulated by its own products. Such a mechanism will form a vicious cycle that accelerates the accumulation of free radicals within microvessels and thus may play a role in the progressing disruption of the blood-brain barrier (BBB) following ischemia.

Animals↗

PubMed1985

Brain and muscle nicotinic acetylcholine receptors are different but homologous proteins.

An alpha-bungarotoxin-binding protein was purified from chick optic lobe and brain by an improved method. Previous and present observations justify its designation as a brain nicotinic acetylcholine receptor (AcChoR). It contains subunits whose apparent molecular weights are somewhat larger than those of subunits of peripheral AcChoRs. The size of the optic lobe AcChoR complex is greater than that of the peripheral receptor when estimated from its sedimentation behavior. Brain AcChoR subunits can be specifically precipitated by a monoclonal antibody directed against chick muscle AcChoR. Amino-terminal amino acid sequence analysis was performed on AcChoR preparations and isolated subunits from the optic lobe and from the rest of the chick brain. The sequences obtained demonstrate that, at least for the lowest molecular weight component, the AcChoRs from different brain areas are identical and they are highly homologous to muscle AcChoR. It is concluded that the brain alpha-bungarotoxin-binding protein is indeed a nicotinic AcChoR and is encoded by a set of genes that is different from, but strongly related to, that for the muscle AcChoR.

Amino Acid Sequence↗

PubMed1992

Evolutionary precedents for behavioral actions of oxytocin and vasopressin.

It is clear that the behavioral actions of oxytocin and vasopressin in mammals are not newly acquired, but have evolutionary antecedents. Injection studies with fish, amphibians, reptiles, and birds indicate that AVT can activate certain reproductive behaviors. The strongest evidence that AVT acts centrally to control reproductive behaviors comes from research on T. granulosa. In this amphibian, injections of AVT agonists activate courtship behaviors (amplectic clasping) in males and egg-laying behaviors in females, whereas injections of AVT antagonists inhibit the behaviors. Also, in Taricha males, AVT concentrations in specific brain areas are associated with the expression of courtship behaviors. Several conclusions about steroid-peptide interactions can be drawn, based on research with this amphibian. First, gonadal steroid hormones act to maintain the behavioral actions of AVT in both males and females. In Taricha, gonadectomy abolishes and steroid implants restore AVT-induced courtship in males and egg-laying in females. Second, gonadal steroids maintain the behavioral actions of AVT, in part, by modulating AVT receptor numbers on target neurons. In Taricha males and females, gonadectomy reduces AVT receptor concentrations (but not binding affinity) in certain brain areas (amygdala pars lateralis) and not others. Third, the type of gonadal steroid determines whether AVT elicits male-like or female-like reproductive behaviors. Ovariectomized Taricha females respond to AVT injections with egg-laying behaviors when implanted with estradiol and with male-like amplectic clasping when implanted with dihydrotestosterone. Fourth, the masculinization of AVT-induced behaviors in females most likely reflects site-specific actions of androgens on AVT-synthesizing neurons. In Taricha, AVTir concentrations in the optic tectum are sexually dimorphic (higher in males than females) and reach peak levels in males during the breeding season. Fifth, AVT content in specific brain areas increase as a function of performing the behaviors. In Taricha, AVTir concentrations in DPOA, CSF, and ventral infundibulum are higher in males that exhibit courtship behaviors than in males that do not. These conclusions illustrate how steroid-peptide interactions in the control of behaviors entail multiple neuroanatomical sites and neurochemical actions.

Animals↗

PubMed1983

Brain organization of sharks, with special reference to archaic species.

Using photographic measurements and normal neurohistological preparations, a number of brains of Galeomorph and Squalomorph sharks were studied and compared. The brains are generally more developed in Galeomorph than in Squalomorph sharks. Among the major brain territories in Galeomorph sharks, the nucleus centralis is prominently enlarged, and the corpus cerebelli is much swollen and fissured. In archaic species such as Scapanorhynchus, Heterodontus, and Chlamydoselachus, the cerebral pallium and corpus cerebelli are less developed than those of taxonomically close species. These results were discussed, in relation to taxonomy, phylogeny and ecology.

Animals↗

PubMed1989

Human neuroethology of emotion.

1. Based on ethological theory, the question of what is the difference between human and nonhuman primate emotionality is investigated. 2. The anatomical basis for this difference is the greater number of neurons in the anterior thalamic nuclei in humans than in monkeys and apes. This may represent an increased differentiation of the limbic message being sent to the cortex. 3. Only humans can report about experiences and subjective feelings in certain motivational states. The two most general states are wakefulness and sleep. The subjective aspect of (desynchronized) sleep is dreaming. The causal relationship between dreaming and certain lower brain stem mechanisms is analysed. 4. Whereas the motor system is usually blocked during desynchronized sleep, there are individuals who voice their emotions and speak while sleeping. As there are essential differences in the substrates for the voluntary control of the voice in the human and nonhuman primates there are essential differences in the voluntary control of emotions. 5. Similar to the motor matching theory of speech perception a motor matching process of affect perception is suggested. 6. The evolutionary change in the human motivational system is thought to be one of several prerequisites for the evolution of language.

Biological Evolution↗

PubMed1999

Comparative analysis of FMRFamide-like immunoreactivity in caiman (Caiman crocodilus) and turtle (Trachemys scripta elegans) brains.

The distribution of FMRFamide (FMRFa)-like peptides in caiman (Caiman crocodilus) and turtle (Trachemys scripta elegans) brains was studied by immunohistochemistry. In both species, distinct groups of FMRFa-like immunoreactive (ir) perikarya were present in the medial septal nucleus, accumbens nucleus, nucleus of the diagonal band of Broca, suprachiasmatic area, lateral hypothalamic area, and periventricular hypothalamic nucleus. A few FMRFa-ir neurons in the hypothalamic area were located in the neuroepithelial cell lining of the third ventricle. FMRFa-ir fibers were scattered in all major areas of the brain, from the olfactory bulbs to the rhombencephalon. They formed dense aggregates in the medial septal area, basal telencephalon, median eminence, and infundibulum, and adjacent to the fourth ventricle. The most obvious difference between the FMRFa-ir systems in caimans and turtles concerned the number of nuclei that contained neurons with this immunoreactivity. Eight such clusters were present in the caiman brain, whereas thirteen clusters were found in the turtle brain. The turtle also displayed scattered FMRFa-ir somata in the anterior olfactory nucleus, striatum, lateral septal nucleus, medial and lateral cortex, medial forebrain bundle, lateral preoptic area, and lateral geniculate nucleus. In the caiman brain, a few FMRFa-ir neurons were noted in the ventrolateral area of the pallial commissure and an even smaller number of ir neurons was found dispersed in the optic tracts. Neither formed nuclear aggregates. The results are compared with those described for other vertebrates.

Alligators and Crocodiles↗

PubMed1998

How to study consciousness scientifically.

The neurosciences have advanced to the point that we can now treat consciousness as a scientific problem like any other. The problem is to explain how brain processes cause consciousness and how consciousness is realized in the brain. Progress is impeded by a number of philosophical mistakes, and the aim of this paper is to remove nine of those mistakes: (i) consciousness cannot be defined; (ii) consciousness is subjective but science is objective; (iii) brain processes cannot explain consciousness; (iv) the problem of 'qualia' should be set aside; (v) consciousness is epiphenomenal; (vi) consciousness has no evolutionary function; (vii) a causal account of consciousness is necessarily dualistic; (viii) science is reductionistic, so a scientific account of consciousness would show it reducible to something else; and (ix) an account of consciousness must be an information processing account.

Biological Evolution↗