Biomedical subjects

H Distel

Publications and source records attributed to H Distel.

34 records · Page 2Linked to original sources

PubMed1989

The dream king's psychiatrist Bernhard von Gudden (1824-1886). A life committed to rationality.

Bernhard von Gudden's life is commemorated as being exemplary for a generation of physicians who in the last century established some of the still valid approaches of modern neuroanatomy, neurology, and psychiatry. His personal contribution to neuroanatomy was the experimental method, major technical advances, and the clarification of the fiber course in the optic chiasm. As a psychiatrist he introduced the humanitarian principle of "no restraint" to German asylums. Although he did not attempt to develop a systematic nosology, he nevertheless founded an influential school of psychiatrists (eg, Forel, Kraepelin, and Nissl). For many years Gudden served as consulting psychiatrist to Bavaria's royal family and drowned together with his patient, King Ludwig II, whose sanity had been questioned.

Germany↗

PubMed1987

Regional autonomy in the peripheral processing of odor signals in newborn rabbits.

In newborn rabbits, small and apparently arbitrary regions of the olfactory bulb and associated epithelium appear capable of a high degree of odor processing. After medial or lateral removal of up to 80% of the olfactory bulbs, including the accessory bulb, newborn pups were still able to respond appropriately to the pheromone-governing suckling behavior (Expt. I), could rapidly learn to associate a novel, artificial odor with suckling (Expt. II), and continued to respond appropriately to artificial odors learned prior to lesioning (Expt. III). These findings suggest that the perception and recognition of such suckling signals does not depend on the integration of information from the entire bulb or epithelium, and question the extent to which patterns of 2-deoxyglucose uptake in the bulb reflect the neural coding for specific odors. However, as the tasks set here only required detection of odor signals and not true odor discrimination, it may still be that the full bulbar pattern of activation is necessary for higher-order processing, such as distinguishing between odors and attributing different meanings to them.

Animals↗

PubMed1986

Pheromonal release of suckling in rabbits does not depend on the vomeronasal organ.

Newborn rabbits are completely dependent on a pheromone present on the mother's belly for the release of the highly stereotyped nipple-search behavior and for nipple attachment. Surgical removal of the vomeronasal organ had no effect on pups' ability to respond to the pheromone when tested on a lactating female, nor on their ability to obtain milk in the normal nursing situation. Lesioned pups could also learn to associate the odor of citral with nipple-search behavior when nursed by a citral-scented doe. In contrast, irrigating the nasal mucosa with ZnSO4 completely eliminated responsiveness both to the pheromone and to the conditioned odor of citral. This is of particular interest given the important role attributed to the accessory olfactory system in pheromonal perception. However, it might be necessary to distinguish between pheromones associated with suckling and therefore peculiar to mammals, and other pheromones.

Animals↗

PubMed1985

The contribution of the olfactory and tactile modalities to the nipple-search behaviour of newborn rabbits.

By performing uni- and bilateral olfactory bulb lesions and uni- and bilateral transsections of the infraorbital branches of the trigeminal nerves in 2-day-old rabbits, it could be shown that: Both the olfactory and tactile modalities are essential for the successful performance of nipple-search behaviour. While bilateral bulbectomy completely eliminates searching, and hence suckling, unilateral bulbectomy has relatively little effect. Bilateral denervation of the muzzle does not eliminate searching, but pups are unable to suckle as they fail to show the mouth-opening component necessary for nipple attachment. In contrast to unilateral bulbectomy, unilateral denervation of the muzzle results in a lateralization of head movements during searching, nipple grasping and nipple release.

Animal Population Groups↗

PubMed1983

Large layer VI neurons of monkey striate cortex (Meynert cells) project to the superior colliculus.

After injections of the enzyme horseradish peroxidase (HRP) into the superior colliculus of macaque monkeys, labelled cells in the neocortex were found to be restricted to layer V in all areas except striate visual cortex. In striate visual cortex, cortico-tectal cells were found both in layer V and in layer VI. The labelled cells in the two layers belonged to morphologically different populations: those of layer V were the common pyramidal cells and those of layer VI were identified as solitary cells of Meynert. This finding may provide new insights into the physiology of the cortico-collicular pathways. It also shows that the striate area in primates differs, with respect to cortico-tectal laminar specificity, from other neocortex.

Animals↗

PubMed1982

Contralateral cortical projections to the superior colliculus in the macaque monkey.

Cortical projections from the contralateral hemisphere to the superior colliculus (SC) were studied in macaque monkey using retrograde transport of the enzyme horseradish peroxidase (HRP). After single or multiple injections of HRP into SC, labelled cells were found contralaterally in layer V of the anterior bank of the arcuate sulcus, the origin of this contralateral projection being confined to the anterior part of Brodmann's area 6. Only a few labelled cells appeared in adjacent area 8. Labelled cells occurred in patches, forming bands which were found to run in a ventromedial direction. A similar pattern was seen homotopically in ipsilateral area 6. Thus, this anterior part of area 6 gives rise to a bilateral projection to the SC. The findings emphasize structural differences in a region of the frontal lobe which has been considered functionally uniform as frontal eye field.

Afferent Pathways↗

PubMed1981

Habenular projections in the monitor lizard (Varanus benegalensis).

The efferent connections of the medial (MHb) and the lateral (LHb) habenular nuclei in the monitor lizard were studied using experimental degeneration techniques. The MHb was found to project to the interpeduncular nucleus and the parvocellular nucleus of the superior raphe via the core portion of the habenulo-peduncular tract (HPT). The LHb fibers form the mantle portion of the HPT and curve laterally to collect again in the ventral tegmentum. From here, they follow either (1) the medial forebrain bundle to terminate in hypothalamus, ventromedial thalamus, preoptic area, and septum, or (2) they continue caudally to terminate in the superior raphe and paramedian reticular formation or (3) they decussate and follow in smaller numbers the ascending and descending pathways on the other side. Some fibers enter the midline and reach the periventricular zone of the midbrain. Short range projections exist to the dorsomedial thalamic nucleus and the paramedian central gray and pretectum. The habenular projections are bilateral, however, much smaller on the contralateral side. Although distinct terminal fields were not found in the substantia nigra and the central gray of the isthmic region, the overall pattern of habenular pathways is strikingly similar to those found in mammals which confirms a long presumed phylogenetic stability of habenular connections.U

Animals↗

PubMed1980

Autoradiographic tracing of developing subcortical projections of the occipital region in fetal rabbits.

Thirty rabbit embryos and two neonates (E18-P1) received micropipette injections of 3H-Leucine into the occipital region of one hemisphere and were killed after 0.5--5 hours. Incorporated tracer was demonstrated by autoradiography of serial sections of the brains. The first axons were seen in the intermediate zone of the developing cerebral cortex, on day E20, and by day E22 they reached the internal capsule. The entire cortico-peduncular bundle and a short branch of the superficial (thalamic) bundle were labeled on day E24. On day E25, additional branches directed to claustrum, thalamus (deep bundle), and cerebellum were distinguished. By day E28 the first indications of terminal field development were observed. One day before birth (E30), the neonate pattern of subcortical pathways was fully established and silver grain condensations were present over most of the subcortical target areas. Subcortically, the axons followed preferentially preexisting fiber tracts. There was a period of at least 2--3 days between the arrival of the supplying bundles at the target sites and the onset of terminal field formation: The axon bundles grew first towards more distal targets, and even beyond, before terminal fields developed proximally. Transient axon bundles reaching the cerebellar paraflocculus and traveling along the pyramidal tract and the external and extreme capsules failed to form terminal fields and disappeared around birth. The data suggest that growth of long axonal tracts and the development of terminal fields are separate phenomena possibly regulated by different mechanisms.

Age Factors↗

PubMed1980

Asymmetric distribution of side preference in hamsters can be reversed by lesions of the caudate nucleus.

Side preferences were tested in Syrian hamsters (Mesocricetus auratus) by placing them on an elevated centerboard which divided a rectangular arena in two equal compartments. When descending from the centerboard all animals turned more often right (79%) than left (21%). After small electrolytic lesions of the left caudate nucleus the side preference was reversed: 31% to the right and 69% to the left. Combined lesions of the left caudate nucleus and left sensorimotor cortex showed similar results; lesions of the left cortex alone had only minor effects. These observations support the hypothesis [28] that side preferences depend on asymmetries of the nigrostriatal system.

Animals↗

PubMed1979

An autoradiographic study of the subcortical projections of the rabbit striate cortex in the adult and during postnatal development.

The subcortical projections of the rabbit striate cortex were studied by autoradiography. Small injections of 3H-leucine were placed into the striate cortex of 15 rabbit pups aged between one day and one month and six adult rabbits (strain Chbb:Ch). Terminal fields of projection occurred only ipsilateral to the injection, and these were found in the caudate nucleus (CN), the claustrum (Cla), the thalamic reticular nucleus (TRN), the dorsal (LGNd) and the ventral (LGNv) lateral geniculate nuclei, the pulvinar (Pul), the ventrolateral (Vl) the posterior (Po) thalamic nuclei, the anterior (APN) and posterior (PPN) pretectal nuclei, the nucleus of the optic tract (NOT), the superior colliculus (SC) and the basal pontine nuclei (PN). Cla was innervated via the superficial corticocortical and CN via the corticocaudate pathways. The remaining projections were innervated via the subcortical pathway which comprised three bundles: The deep bundle (to TRN, LGNd, Pul and Po), the superficial bundle (to LGNv, APN, PPN, NOT, and SC), and the peduncular bundle (to PN). The projection to SC showed remarkable changes of its terminal pattern during the first and second postnatal weeks. These changes were characterized by a strong reduction of the horizontal extension of the terminal labelling and an increasing concentration on the stratum griseum superficiale. Similar changes were not observed in the other projections.

Age Factors↗

PubMed1978

Behavior and electrical brain stimulation in the green iguana, Iguana iguana L. II. Stimulation effects.

Behavioral responses were electrically elicited in the brains of 21 green iguanas. At 518 stimulation sites, a limited number of behaviors could be reliably elicited. Except for some motor responses which had a forced appearance, they corresponded to the basic activity of green iguanas, exploratory behavior, display, defensive and escape-related behavior. Head-nodding displays were reliably elicited post stimulation when imminent escape was prevented experimentally but rarely during stimulation. Goal-directed behavior, i.e., feeding, drinking, mating and fighting behavior, were not elicited. The stimulation sites of frequently elicited behavioral responses revealed regional differences and some structural correlations. The majority of sites yielding defensive display responses were found in the hypothalamus, while dewlap display was more readily and widely elicited. Axial rotation and head-raising were elicited in a ventrothalamic zone extending into the tegmentum mesencephali. Tongue-flicking response sites were mostly concentrated in ventromedial areas of the tel-, di- and mesencephalon. Most escape-related responses were distributed unspecifically but the sites of violent flight responses were confined to the dorsal and lateral mesencephalon.

Animals↗

PubMed1978