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PubMed1989

Topography of oxytocin and vasopressin neurons in the forebrain of Equus caballus: further support of proposed evolutionary relationships for proopiomelanocortin, oxytocin and vasopressin neurons.

The present study describes the topography of immunoreactive (ir) oxytocin (OXY) and vasopressin (AVP) neurons in the forebrain of Equus caballus and the coexistence of ir proopiomelanocortin (POMC)-derived peptides in the same cells. These data are compared to those for other mammalian species and the possible significance of species variations is considered. As expected, magnocellular neurons of the equine hypothalamus, which contain ir OXY or AVP, have prominent discernible projections to the neurohypophysis. Further, as in other mammalian species, the field of ir OXY perikarya generally extends rostral and dorsal to groups of ir AVP cell bodies, and caudal projections from OXY neurons appear to be more numerous than ir AVP projections to the brainstem and/or spinal cord. Interestingly, however, the brain of E. caballus also contains: (1) perikarya staining for OXY in the arcuate nucleus, (2) ir AVP and OXY cell bodies in the suprachiasmatic nucleus, and (3) neurons in the supraoptic and paraventricular nuclei that stained for beta-endorphin but not for other posttranslational products of POMC or dynorphin. These results give further credence to the proposal that there is an evolutionary relationship between OXY-, AVP- and POMC-producing hypothalamic neurons. Whether or not species differences in peptide coexistence reflect functional differences in neuronal populations or species differences in residual genomic expression by these neuroendocrine cells warrants further investigation.

Animals↗

PubMed1990

Protein synthesis and the heart shock/stress response after ischemia.

It has been appreciated for many years that the recovery of brain protein synthesis activity following a transient ischemic insult lags considerably behind the normalization of brain energy metabolism. More recently, selective increases or decreases in the synthesis of specific proteins have been documented to occur during postischemic recirculation, the best characterized of such changes being the induction of proteins characteristic of the "heat shock" or "stress" response. This review will summarize these developments in the study of changes in gene expression following ischemia, with an emphasis on regional differences in the vulnerability of overall translational activity as well in the expression of stress proteins and their mRNAs. The neuronal localization of the 70 kDa heat shock protein, hsp70, after ischemia is contrasted with its largely glial and vascular induction following a hyperthermic stress. The lasting depression of protein synthesis and sustained expression of hsp70 mRNA in vulnerable hippocampal CA1 neurons appear to be mechanistically related and may constitute markers for cellular pathophysiology leading to neuronal cell loss. Elucidating the mechanisms responsible for cell-specific regulation of stress proteins and other gene products may eventually contribute to a more precise understanding of the evolution of brain injury at the molecular level following diverse insults.

Animals↗

PubMedDate not supplied

A neuro-evolutionary approach to the anxiety disorders.

BACKGROUND: Advances in our understanding of the anxiety disorders and in the application of evolutionary principles to medicine provide the possible basis for a neuro-evolutionary approach to these conditions. In this paper, initial steps taken towards such an approach are described. METHODS: Neuro-evolutionary accounts of each of the anxiety disorders have been offered. Notably, several of these accounts have suggested that particular anxiety disorders are mediated by specific brain-based false alarms. This paper reviews the strengths and weaknesses of such accounts. RESULTS: The false suffocation alarm of panic attack is the most fully elaborated of the neuro-evolutionary accounts of an anxiety disorder. However, viable neuro-evolutionary approaches have also been offered for other anxiety disorders, such as obsessive-compulsive disorder and social phobia. CONCLUSIONS: Further work is necessary to consolidate a neuro-evolutionary approach to the anxiety disorders. Although the theoretical basis for such an approach has become increasingly appealing over the last several years, this foundation requires supplementation by further empirical research.

Adolescent↗

PubMed1999

The contribution of Hughlings Jackson to an understanding of dissociation.

The author provides a preliminary framework for a systematic and dynamic understanding of dissociation through a consideration of the theories of Hughlings Jackson. Jackson's ideas are briefly reviewed. He saw the proper scientific investigation of mental illness as an experimental investigation of mind. Accordingly, his argument begins with this fundamental concept. His views of the brain-mind relationship and of mind, or self, resemble modern conceptions. He viewed the self as double and focused on those disruptions of the self system which he called the "dreamy state." This state involves an "uncoupling" of normal consciousness, resulting in the loss of the most recently developed forms of memory and of the stream of consciousness. Dissociation is seen here as analogous to the dreamy state. Jacksonian theory predicts the main features of dissociation, i.e., constriction of consciousness, a particular form of amnesia, disaggregation of perceptual phenomena, depersonalization, derealization, and hallucinosis. It leads to the view that dissociation can be seen, in essence, as an uncoupling of consciousness.

Biological Evolution↗

PubMed1990

c-pathway polysialogangliosides in the nervous tissue of vertebrates, reacting with the monoclonal antibody Q211.

The mouse monoclonal antibody Q211, previously shown to recognize a common epitope of chicken brain GP1c and of two other polysialogangliosides containing 4 and 6 sialic acid residues respectively, is demonstrated to bind to gangliosides with identical thin-layer chromatography (TLC) migration in the brain of representatives of boney fish, rays, reptiles and mammals, including man. In the boney fish brains, the Q211 binding gangliosides were found to be alkali-labile, the Q211 epitope, however, is alkali-stable. After alkaline treatment, the cichlid fish contained at least 4 Q211-binding gangliosides, migrating as GT1c, GQ1c, GP1c and 'GH'. In the trout brain only one Q211 antigenic fraction was found, migrating as GQ1c. In the brains of ray, turtle and embryonic chicken an identical pattern of Q211-binding gangliosides (GQ1c, GP1c, 'GH') occurred. In the embryonic rat and human brain, the content of Q211-binding gangliosides was much lower as compared to the other vertebrate species. The epitope was found in two fractions, migrating like GQ1c (human and rat) and GP1c (rat). The presence of Q211 epitope in all species was confirmed by immunohistochemistry. These data confirm that the Q211-epitope contains a complete c-ganglio-tetraose structure, carrying 3 sialic residues at the inner galactose. They furthermore demonstrate that the expression of c-pathway polysialogangliosides is a general feature of the vertebrate nervous tissue, either during whole life (fish, reptiles) or more or less transient during embryonic development (birds, mammals).

Animals↗

PubMedDate not supplied

Origin of the vertebrate visual cycle.

In vertebrates, the absorption of light by rhodopsin leads to the isomerization of 11-cis-retinal chromophore to its all-trans form. In the visual cycle, all-trans retinal is converted back to 11-cis retinal. Mammalian visual cycle takes place in photoreceptor cells and retinal pigment epithelial (RPE) cells, while that of cephalopods is completed within a photoreceptor cell. To identify visual cycle system in the primitive chordate ascidians, we studied the localization of the ascidian visual cycle genes and proteins by in situ hybridization and whole-mount immunohistochemistry, respectively. We identified four genes encoding putative visual cycle proteins, homologs of retinal G protein-coupled receptor (Ci-opsin3), cellular retinaldehyde-binding protein (Ci-CRALBP), beta-carotene 15,15'monooxygenase (Ci-BCO) and RPE-specific 65 kDa protein (Ci-RPE65) in the ascidian, Ciona intestinalis. In contrast to Ci-BCO, which is predominantly localized in ocellus photoreceptor cells of the larva, Ci-RPE65 is not significantly expressed in the ocellus and brain vesicle of the larva. Ci-RPE65 is expressed in the neural complex, a photoreceptor organ of the adult ascidian, at a level comparable with that of Ci-opsin3 and Ci-CRALBP. Proteins of Ci-opsin3, Ci-CRALBP and Ci-BCO are localized in photoreceptor cells. These results suggest that the larval visual cycle uses Ci-opsin3 as a photoisomerase, while the visual cycle of the adult photoreceptors is RPE65-dependent. The colocalization of visual cycle proteins in the photoreceptor cells suggest that ascidian visual cycle takes place in a photoreceptor cell as seen in the cephalopod visual cycle.

Animals↗

PubMed2002

Right-sided human prefrontal brain activation during acquisition of conditioned fear.

This H2(15)O positron emission tomography (PET) study reports on relative regional cerebral blood flow (rCBF) alterations during fear conditioning in humans. In the PET scanner, subjects viewed a TV screen with either visual white noise or snake videotapes displayed alone, then with electric shocks, followed by final presentations of white noise and snakes. Autonomic nervous system responses confirmed fear conditioning only to snakes. To reveal neural activation during acquisition, while equating sensory stimulation, scans during snakes with shocks and white noise alone were contrasted against white noise with shocks and snakes alone. During acquisition, rCBF increased in the right medial frontal gyrus, supporting a role for the prefrontal cortex in fear conditioning to unmasked evolutionary fear-relevant stimuli.

Adult↗

PubMed1980

The brain of the mammal-like reptile Probainognathus jenseni (Therapsida, Cynodontia). A correlative paleo-neoneurological approach to the neocortex at the reptile-mammal transition.

A natural endocranial cast of the South American cynodont Probainognathus jenseni is studied, and an evaluation of the probable nature of the neocortex at the level of certain cynodonts of the Middle Triassic is made, based in the available paleo-neoneurological information. The endocast of Probainognathus shows well developed olfactory bulbs, long cerebral hemispheres, small anterior colliculi and well represented cerebellum and flooculi. The pineal gland may have been located between the caudal hemispheric poles. No parietal foramen exists. The dorsal surface of the cerebral hemispheres shows a slope at the level of the anterior edge of the caudal fourth part, which is interpreted as the posterior limit of the neocortical plate. At the level of the olfactory peduncles, it is visible a stem vessel; one of its branches distributes on the anterior part of the lateral border of the hemisphere. It is advanced the interpretation that this latter vessel could indicate the paleo-neocortical boundary. The analysis of the neoneurological information led the author to suppose that the neocortex of Probainognathus, and surely of other cynodonts of the Middle Triassic, has shown supplementary somatic sensory and motor, visual and auditory representations, and perhaps incipient primary somati sensory and motor ones, advancing a "polymodal cortex", as it is supposed had stem mammals. Moreover, the histostructure of the neocortex at this state of the evolution may have been in a proisocortical-isocortical stage, that is, in the beginnings of the true neocortex. The confrontation of the paleoneurologic with the neoneurologic information led the author to suppose that Triconodon and Ptilodus have had a neocortex, surely more developed than Probainognathus, but that it is not seen in the endocasts at present studied. The quantitative analysis of Probainognathus' endocast, as well as those of other cynodonts, suggest that certain cynodonts of the Middle Triassic were in an advanced state toward endothermy.

Animals↗

PubMed2003

The place of the Triune Brain in psychiatry.

MacLean's pioneering concept of "The Triune Brain" began to emerge in 1949 with his publication Psychosomatic disease and the "visceral brain", followed in 1952 by Some psychiatric implications of physiological studies on frontotemporal portion of limbic system (visceral brain). This shows that his seminal ideas grew out of his astute observation of psychiatric signs and symptoms. Later on, he observed the broad spectrum of human epileptic seizures and its cause in the limbic system. A large variety of uncontrolled feelings and emotions, together with bizarre motor behavior, is elicited by seizures in the hippocampus and other limbic structures.Meanwhile, based on the triune brain model, a new approach to psychopathology has taken shape. It is the evolutionary perspective of mental diseases such as the major psychoses, anorexia nervosa, anxiety disorders, and also brain diseases such as Parkinson's disease or Huntington's disease. Many mental illnesses are marked by severe deficits in social behavior and social communication. The social communication system disintegrates, especially in the major psychoses. The response choices to social or other external signals in a given situation become limited or even distorted, and reasoning is no longer part of decision making. The emphasis of this contribution is on the disintegration of social behavior in psychopathology, based on evolutionary psychiatry. MacLean's concept provides valuable insight for understanding the biological roots of human social behavior and communication. It is time to uncover the ties between the natural and the social sciences.

Animal Communication↗

PubMed1983

A stone's throw and its launch window: timing precision and its implications for language and hominid brains.

Did bigger brains for more precise throwing lead to language, much as feathers for insulation may have set the stage for bird flight? Throwing rocks even at stationary prey requires great precision in the timing of rock release from an overarm throw, with the "launch window" narrowing eight-fold when the throwing distance is doubled from a beginner's throw. Paralleled timing neurons can overcome the usual neural noise limitations via the law of large numbers, suggesting that enhanced throwing skill could have produced a strong selection pressure for any evolutionary trends that provided additional timing neurons. This enhanced timing circuitry may have developed secondary uses for language reception and production.

Animals↗

PubMedDate not supplied

The neurobiological consequences of early stress and childhood maltreatment.

Early severe stress and maltreatment produces a cascade of neurobiological events that have the potential to cause enduring changes in brain development. These changes occur on multiple levels, from neurohumoral (especially the hypothalamic-pituitary-adrenal [HPA] axis) to structural and functional. The major structural consequences of early stress include reduced size of the mid-portions of the corpus callosum and attenuated development of the left neocortex, hippocampus, and amygdala. Major functional consequences include increased electrical irritability in limbic structures and reduced functional activity of the cerebellar vermis. There are also gender differences in vulnerability and functional consequences. The neurobiological sequelae of early stress and maltreatment may play a significant role in the emergence of psychiatric disorders during development.

Adolescent↗

PubMed2000

[Gender in the brain. A critical scrutiny of the biological gender differences].

Down through history, biological arguments have often been used to legitimize a social gender order characterized by male supremacy. In the 1990's, a lively debate on the biological grounds of gender differences once again emerged in various fields. In the present article, the biological models used for explaining cognitive and behavioral gender differences are scrutinized, and recent research is discussed in light of history. These biological models emanate from theories about sex hormones, genetics and brain anatomy. Regarding the cognitive effects of sex hormones, no consensus has been reached, indicating a need for further research. Studies of relationships between genetics on the one hand and sexual orientation and behavior on the other are theoretically obscure and have thus far failed to prove a trustworthy connection. While there is indeed a difference in total brain size--men's brains are heavier than women's--it is not known whether this difference has any import beyond the fact that men have larger bodies. The existence of differences in brain lateralization and the size of the corpus callosum have been powerfully dismissed in several recent reviews. The design and interpretation of medical research in this field are still colored by gender-stereotyped preconceptions and expectations, which obstructs efforts to gain a solid understanding of the biological differences/similarities between men and women. The media's interest in publicizing research results on gender differences, irrespective of magnitude or practical significance, further alerts us to the importance of scientific reason. There exists a very real risk today that medical gender research may be reduced to research about differences. If this problem is not addressed, it might lead to the reinforcement of the gendered structures of society.

Behavior↗

PubMed2004

The complex identity of brain tumors: emerging concerns regarding origin, diversity and plasticity.

Elucidation of genetic and epigenetic mechanisms underlying neoplasia is one of the great success stories of modern science, but this success has not been associated with parallel improvements in the treatment of malignant tumors. One possible explanation for this failure is that the most important variables that support growth of malignancies are not yet identified. Another possible explanation, however, is that multiple variables important in neoplastic progression combine to create a level of disease complexity not taken into account by current therapeutic approaches. The study of development and neoplasia in the CNS provides some of the strongest support for the latter view--a view that, if correct, would suggest that a radical rethinking of the biology of malignancy is required if we are to make progress in the treatment of this important medical condition.

Animals↗

PubMed1997

Avian homologues of mammalian intralaminar, mediodorsal and midline thalamic nuclei: immunohistochemical and hodological evidence.

This paper presents and reviews data suggesting that the dorsal thalamic zone (abbreviated DTZ) in birds is homologous to the intralaminar, midline, and mediodorsal thalamic nuclear complex (abbreviated IMMC) in mammals. The DTZ is located dorsomedially in the diencephalon of birds and consists of several subnuclei: nucleus dorsomedialis anterior thalami (DMA), nucleus dorsomedialis posterior thalami (DMP), nucleus dorsolateralis anterior thalami, pars medialis (DLM), nucleus dorsointermedius posterior thalami (DIP), nucleus dorsolateralis posterior thalami (DLP), and nucleus subhabenularis lateralis (SHL). Our immunohistochemical studies show that: (1) SHL and medial and dorsal parts of DMA and DMP are relatively rich in GABAergic, enkephalin-containing, substance P-containing, and cholinergic fibers; (2) lateral parts of DMA and DMP are relatively poor in these neurotransmitters; and (3) DIP, DLP, and DLM are moderately rich in cholinergic and substance P-containing fibers. Our retrograde pathway tracing studies indicate that the DIP and DLP in the more lateral parts of DTZ project to somatic striatum, while the DMA, DMP, and SHL located more medially in the DTZ project to visceral/limbic striatum. Our anterograde tracing studies indicate that DIP receives afferents from the dorsal pallidum, whereas DMA and DMP appear to receive afferents from both the ventral striatum and ventral pallidum. Diverse prior studies have shown that in general medial and lateral components of DTZ are connected with visceral/ limbic and somatic brain regions, respectively. These characteristics indicate that: (1) SHL and medial and dorsal parts of DMA and DMP are comparable to mammalian midline thalamic nuclei, including the medial components of the intralaminar nuclei; (2) lateral parts of DMA and DMP are comparable to the mediodorsal nucleus in mammals; (3) DIP is comparable to the parafascicular nucleus in mammals; and (4) DLM and DLP are comparable to the laterally located intralaminar nuclei in mammals. The comparability of avian DTZ and mammalian IMMC suggests that they evolved from thalamic precursor nuclei present in the common reptilian ancestors and that they may perform similar roles in the movement control function of the basal ganglia.

Animals↗

PubMed2006

Endogenous cannabinoids in the brain and peripheral tissues: regulation of their levels and control of food intake.

Endocannabinoids were first defined in 1995 as 'endogenous substances capable of binding to and functionally activating the cannabinoid receptors'. To date, two well-established endocannabinoids, N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), as well as a few other putative ligands, all derived from long-chain polyunsaturated fatty acids, have been identified in animal tissues. The biosynthetic and metabolic pathways for anandamide and 2-AG have been elucidated, and most of the enzymes therein involved have been cloned. We now know that CB1 receptors, and endocannabinoids in tissue concentrations sufficient to activate them, are more widely distributed than originally thought, and are found in brain and peripheral organs involved in the control of energy intake and processing, including the hypothalamus, nucleus accumbens, brainstem, vagus nerve, gastrointestinal tract, adipose tissue and liver. Endocannabinoid biosynthetic and inactivating pathways are under the regulation of neuropeptides and hormones involved in energy homeostasis, and endocannabinoid levels are directly affected by the diet. Endocannabinoids, in turn, regulate the expression and action of mediators involved in nutrient intake and processing. These cross-talks are at the basis of the proposed role of endocannabinoid signalling in the control of food intake, from invertebrates to lower vertebrates and mammals, and their perturbation appears to contribute to the development of eating disorders.

Appetite Regulation↗

PubMed1994

Structural order of membranes and composition of phospholipids in fish brain cells during thermal acclimatization.

A comparison of the structural orders of membranes of a mixed brain-cell population isolated from Cyprinus carpio L. acclimated to either summer (23-25 degrees C) or winter (5 degrees C) revealed a high degree of compensation (80%) for temperature, as assayed by electron spin resonance spectroscopy. The cells rapidly forget their thermal history and adjust the physical properties of the membranes when shifted to the other extreme of temperature either in vivo or in vitro. Phospholipids separated from both types of animals exhibit only around 10% compensation. Arachidonic and docosahexaenoic acids are the major polyunsaturated fatty acids in the brains, but the fatty acid composition of the brain total phospholipids does not vary with adaptation to temperature. Separation of phosphatidylcholines and phosphatidylethanolamines into molecular species revealed a 2- to 3-fold accumulation of 18:1/22:6, 18:1/20:4, and 18:1/18:1 species in the latter; 18:0/22:6 showed an opposite tendency. Molecular species composition of phosphatidylcholines did not vary with the temperature. The same trends of changes were seen with brains of freshwater fish from subtropical (Catla catla L.) or boreal (Acerina cernua) regions. It is concluded that the gross amount of docosahexaenoic acid (22:6) plays only a minor role in adjusting the membrane physical properties to temperature. Factors other than lipids might be involved in the adaptation processes. Due to their specific molecular architecture, molecules such as 18:1/22:6, 18:1/20:4, or 18:1/18:1 phosphatidylethanolamine might prevent the contraction of membranes in the cold and may provide an environment for some other components involved in the temperature regulation of physical properties of nerve cell membranes.

Acclimatization↗

PubMed2002

The role of prefrontal cortex in working-memory capacity, executive attention, and general fluid intelligence: an individual-differences perspective.

We provide an "executive-attention" framework for organizing the cognitive neuroscience research on the constructs of working-memory capacity (WMC), general fluid intelligence, and prefrontal cortex (PFC) function. Rather than provide a novel theory of PFC function, we synthesize a wealth of single-cell, brain-imaging, and neuropsychological research through the lens of our theory of normal individual differences in WMC and attention control (Engle, Kane, & Tuholski, 1999; Engle, Tuholski, Laughlin, & Conway, 1999). Our critical review confirms the prevalent view that dorsolateral PFC circuitry is critical to executive-attention functions. Moreover, although the dorsolateral PFC is but one critical structure in a network of anterior and posterior "attention control" areas, it does have a unique executive-attention role in actively maintaining access to stimulus representations and goals in interference-rich contexts. Our review suggests the utility of an executive-attention framework for guiding future research on both PFC function and cognitive control.

Animals↗

PubMed2003

PACAP in avians: origin, occurrence, and receptors--pharmacological and functional considerations.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a novel member of the secretin/glucagon/vasoactive intestinal peptide (VIP) superfamily. In vertebrates, including avians, it occurs in two forms: PACAP(38) and PACAP(27). PACAP structure is well conserved during evolution, being identical in mammals, and showing one amino acid dfifference in avians (chick, turkey). PACAP is widely distributed in the central nervous system and peripheral tissues and displays a pleiotropic activity, including functions as a hypophysiotropic hormone, neuromodulator, and neurotrophic factor. PACAP exerts its biological actions through three types of receptors designated PAC(1), VPAC(1) and VPAC(1). This review (1) presents the current knowledge on PACAP origin, distribution and function, (2) compares the avian findings with those found in mammals, and (3) describes receptor-linked mechanisms in avians, including recent data on receptor-related signal transduction pathways, with a special emphasis on receptor pharmacology and function.

Amino Acid Sequence↗