Showing papers on "Thalamus published in 1974"

Retrograde axonal transport and the demonstration of non-specific projections to the cerebral cortex and striatum from thalamic intralaminar nuclei in the rat, cat and monkey.

Abstract: The intralaminar nuclei of the thalamus have been examined particularly in the rat but with additional observations in the cat and squirrel monkey, with a view to determining the extent of their connections with the cerebral cortex and/or striatum. Cells in the intralaminar and other thalamic nuclei were labeled by retrograde axonal transport of the enzyme, horseradish peroxidase, from injection sites of varying size in the cerebral cortex and striatum. This system provides a useful means of determining certain parameters of the horseradish peroxidase technique. It is concluded that the degree of retrograde labeling of a cell is primarily dependent upon the number and concentration of its axon terminals in the vicinity of the injection site. Injections of the striatum in the rat and monkey cause intense labeling of many cells in the intralaminar nuclei. Conversely, injections in the medial, frontal and parietal cortex of all three species, though leading to heavy labeling of many cells in the appropriate thalamic relay nuclei, result in only light labeling of relatively few cells in the intralaminar nuclei. Cells in a single intralaminar nucleus, however, though showing a broad topographical relationship, can be labeled from quite wide areas of the cerebral cortex. These results are consistent with the view that the intralaminar nuclei (including the parafascicular and centre median) project densely to the striatum and sparsely and diffusely upon the cerebral cortex.

Corticofugal projections from the visual cortices to the thalamus, pretectum and superior colliculus in the cat.

Abstract: Small lesions were placed in visual cortical areas 17, 18, 19, 20, 21, 7, and Clare-Bishop in the cat, and the sites of terminal degeneration seen with Fink-Heimer technique were plotted in thalamus, pretectum and superior colliculus. No degeneration was found in these sites after area 20 lesions; lesions in the other cortical areas gave different patterns of degeneration. Two major patterns were present, one from lesions in 17–18, one from lesions in 21, 7 and C-B, with degeneration from 19 forming a transition between the two groups. Areas 17, 18 and 19 project to the dorsolateral geniculate nuclear complex (LGNd); areas 21, C-B and 7 do not. Area 17 projects to the laminar part, area 18 to both laminar and interlaminar (NIM) parts, and 19 only to NIM. The corticogeniculate projections from all three areas are topically organized anteroposteriorly, and at least that from area 17 is topically organized mediolaterally. Areas 17 and 18 project topically to a columnar locus of the medial pulvinar (=lateral posterior) nucleus which ventrally includes that area known as the posterior nucleus. Area 19 has a double columnar projection to this part of the thalamus, one in the medial and one in the lateral pulvinar area. The medial column lies medial to that from 17–18, and appears to overlap the termination of the ascending projection from the superior colliculus. Cortical areas 21, C-B and 7 also have a double projection to the pulvinar. These findings indicate that the corticorecipient neurons in both medial and lateral sectors of the pulvinar are organized so that dorsal neurons are activated by stimuli in upper visual fields (lower retina) and ventral neurons by stimuli in lower fields (upper retina). Areas 17 and 18 project to the external layer of the ventrolateral geniculate (LGNv) nucleus, 19 to both external and internal layers, and 21, C-B and 7 to internal layer only. The pretectal projection from 17–18 is limited to its caudal pole chiefly in the posterior pretectal nucleus (NPP), and also in the nucleus of the optic tract (NOT). Area 19 fibers terminate in NPP, NOT and also in the reticular part of the anterior pretectal nucleus (NPAr). Those from 21 and C-B end primarily in NPAr, and from area 7 in both reticular and compact parts of NPA. These corticopretectal systems all appear to be organized topically. Areas 17, 18 and 19 have a double termination in the superior colliculus, a focal pattern in the superficial layers (chiefly lamina II), and a diffuse pattern in deeper layers (laminae IV, V, VI). The superficial pattern only provides the retinotopical matching with the optic afferents. All other cortical areas project diffusely to the deep layers. After lesions in 21 and C-B, the superficial foci are larger and centered in lamina III; after area 7 lesions this focal degeneration is centered in laminae III and IV and spread over much of the width of the colliculus. Degeneration to pontine nuclei and inferior olive was not examined.

The adrenergic innervation of the rat thalamus as revealed by the glyoxylic acid fluorescence method

Abstract: The adrenergic innervation of the thalamus, epithalamus, metathalamus, and subthalamus in the rat has been investigated by means of the recently introduced glyoxylic acid fluorescence method. Many areas of the thalamus and adjoining regions, that appear sparsely innervated by catecholamine (CA) fibers in specimens processed according to the standard Falck-Hillarp formaldehyde method, were found to be richly supplied with such fibres in the glyoxylic acid-treated specimens. Moreover, the glyoxylic acid method allows the tracing of the CA axons from the cell bodies up to the terminals, and in combination with stereotaxic lesions the following CA systems to the thalamus could be established: 1 The locus coeruleus system. Most of these axons ascend in the so-called dorsal tegmental bundle through the mesencephalon and the zona incerta into the medial forebrain bundle. From this bundle branches were traced along several routes, giving rise to extensive terminal systems in many thalamic, metathalamic and pretectal areas, most notably the anterior, ventral and lateral nuclear complexes, and the medial and lateral geniculate bodies. 2 The dorsal periventricular bundle, which constitutes a previously not described adrenergic component of the dorsal longitudinal fasciculus. This system originates in cell bodies (defined as the A11 cell group) in the dorsal raphe region, the central gray of the mesencephalon, and in the periventricular gray of the caudal thalamus. The axons ascend within the dorsal longitudinal fasciculus and give rise to a thalamic and hypothalamic periventricular system, projecting to medial and midline thalamic, epithalamic and pretectal regions. 3 Part of the terminals in the paraventricular thalamic nucleus was identified with a non-locus projection from cell bodies in the pontine or medullary reticular formation. 4 A system of delicate, probably dopamine-containing axons was revealed in the caudal thalamus, the zona incerta and the dorsal and anterior hypothalamus. This system probably originates in the dopamine cell bodies of the diencephalic A11 and A13 cell groups, forming a hitherto unknown intradiencephalic dopaminergic system. The adrenergic afferent systems to the thalamus can, to a large extent, be regarded as adrenergic components of known ascending reticular projections. The information on the adrenergic systems obtained with the glyoxylic acid method revealed new features of the organization of the thalamic projections from the brain stem reticular formation.

Cytoarchitecture and somatic sensory connectivity of thalamic nuclei other than the ventrobasal complex in the cat

Abstract: This study is a re-examination, using autoradiographic and axonal degeneration methods, of the distribution of spinal, dorsal columnlemniscal and cortico-thalamic fibers within the thalamus of the cat. The emphasis was placed upon making an exact cytoarchitectonic delineation of regions outside the ventrobasal complex which receive spino-thalamic fibers and corticofugal fibers arising in the sensory-motor regions of the cerebral cortex. It is concluded, in agreement with Boivie ('70, '71a,b) that spino-thalamic fibers arising below the level of the lateral cervical nucleus terminate, not in the ventrobasal complex, but in a recognizable portion of the ventrolateral complex adjacent to the ventrobasal complex. This region appears to be also the thalamic relay for Group I muscle afferents. Combined experiments in which, in the same animal, the dorsal column-lemniscal path was labeled autoradiographically and the spino-thalamic path by the Nauta method, indicate virtually no overlap of the two systems in the ventral nuclear complex. Spinal fibers also end in the medial division of the posterior group (Pom), which extends posteriorly as a small-celled zone along the ventromedial aspect of the magnocellular medial geniculate nucleus. Reports of spinal terminations in the magnocellular nucleus proper may result from a failure to recognize the extent of Pom. A third part of the thalamus receiving spinal fibers consists of a posteriorly situated group of large, deeply staining cells belonging to the central lateral nucleus which lie mainly posterior to the internal medullary lamina and which, as Mehler ('69) has mentioned, have previously been confused with the centre median and parafascicular nuclei. Corticofugal fibers arising in the somatic sensory cortex terminate in both the ventrobasal complex and the spinal part of the ventrolateral complex as well as in the central lateral nucleus and Pom and this confirms the work of Rinvik ('68a). Those arising in the motor cortex terminate only in (a different part of) the ventrolateral complex and in the centre median nucleus.

Nucleus ventroposterior inferior (VPI) as the vestibular thalamic relay in the rhesus monkey I. Field potential investigation

Abstract: In order to investigate the thalamic relay of the vestibulo-cortical pathway, field potentials were recorded in the rhesus thalamus under pentobarbital anesthesia. Short latency responses (2.5 msec on the average) upon stimulation in isolation of the vestibular nerve were recorded in the inferior ventroposterior nucleus (VPI). These potentials were abolished after transection of the vestibular nerve but were not affected by total cerebellectomy. Projection of VPI neurons to the primary vestibular cortex was demonstrated by antidromic stimulation. Field potentials with latencies of those observed in the vestibular cortex (about 5 msec) in response to vestibular nerve stimulation were recorded in other areas of the thalamus (ventrobasal, ventrolateral, posterior group, including magnocellular medial geniculate nuclei). Thus, the VPI rather than the other nuclei with long latency responses is likely to be the thalamic relay in the vestibulo-cortical path. The close topographical relationship between vestibular and somatic areas in the cortex is parallelled in the thalamus, the VPI being closely related to VPL and VPM nuclei.

Cortical and pallidal projections to the nucleus ventralis lateralis thalami. Electron microscopical studies in the cat.

Abstract: The nucleus ventralis lateralis (VL) and ventralis anterior (VA) thalami have been studied with the electron microscope following lesions of the cerebral cortex and of the nucleus entopeduncularis which represents the homologue of the medial pallidal segment in primates. It has been confirmed that VL receives a substantial number of afferents from the motor cortex, while cortical fibers to VA originate mainly rostral to the precruciate gyrus. Corticofugal fibers terminate in VL/VA as type SR boutons (Rinvik and Grofova, 1974a) and establish synapses with relay cell dendrites and with vesicle-containing dendrites. Four to five days following large lesions of the entopeduncular nucleus an electron-lucent form of degeneration occurs in one type of boutons in VL. These boutons are greatly swollen and vesicle-depleted, and contain altered mitochondria, an increased number of glycogen particles, irregular membrane structures and vacuoles. Some of the electron-lucent boutons progress into electron-dense forms at later survival times. Boutons showing these degenerative changes establish symmetrical synapses with relay cell dendrites and/or cell bodies. They do not synapse upon vesicle-containing dendrites and they are never engaged in the VL glomeruli. It is concluded that they belong to the type F1 boutons (Rinvik and Grofova, 1974a). Similar initial electron-lucent changes are seen in boutons in the nucleus centrum medianum (CM) ipsilateral to the entopeduncular lesions. No evidence was found for a projection from the entopeduncular nucleus to VA. The findings are discussed with regard to relevant morphological and physiological data in the literature. Particular attention is paid to the interaction at the cellular level in VL between afferents from the intracerebellar nuclei, motor cortex and globus pallidus.

Characteristics of projections from the nucleus ventralis lateralis to the motor cortex in the cats: an anatomical and physiological study.

Abstract: The properties of neurons in the nucleus ventralis lateralis (VL) of thalamus were examined by anatomical and electrophysiological methods and the following results were obtained: 1. There were two types of projection fibers from VL to the motor cortex. One type projected to a limited area of the cortex, the other arborized extensively and projected to a wide area of the cortex. 2. The widely arborizing projection fibers, i.e., wide projection fibers, showed a special terminal bush which was different from that of the specific projection fibers of VPL and spread as widely as 1.0 mm2 within the III layer of the motor cortex. 3. Neither narrow nor wide projection fibers carried specific information from the periphery but rather diffuse information arising from deep structures such as joints and periosts. 4. Both types of projection fibers branched somewhere in the white substance and projected to different areas of the motor cortex. 5. The chronaxie of these fibers was about the same as that of PT cells but considerably longer than spinal interneurons. The excitability of these fibers was lower than that of PT cells indicating that weak intracortical microstimulation (ICMS) does not excite these fibers. 6. The possible functional role of wide projection fibers was discussed in relation to the cortical efferent zones.

Thalamic organization of the retmo-thalamo-hyperstriatal pathway in the pigeon (Columba Livia)

Abstract: 1. The distribution of labeled macromolecules was studied within the dorsolateral thalamic nuclei of the pigeon after unilateral intraocular injection of either 3H-proline, 3H-leucine or 3H-fucose. The highest densities of grains were found in nucleus dorsolateralis anterior, pars lateralis at its dorsolateral aspect (DLLd) and in nucleus lateralis anterior (LA) whereas moderate labeling was observed in the ventral aspect of DLL (DLLv) and in nucleus dorsolateralis anterior, pars magnocellularis (DLAmc). No significant label was found on the ipsilateral side. 2. After circumscribed unilateral ablation of the visual wulst, the cells in DLLv were most severely affected by retrograde degeneration, whereas DLLd, DLAmc and LA remained intact. Bilateral ablation of the wulst or combination of wulst damage with section of the supraoptic decussation gave rise to additional degeneration in DLLd, thus suggesting a contralateral retinotelencephalic pathway via DLLv and an ipsilateral retino-telencephalic pathway via DLLd and recrossing via DSO. LA and DLAmc represent relays in retinothalamo-telencephalic pathways of unknown destination. 3. DLLv was confirmed as relay in the contralateral retino-thalamo-hyperstriatal pathway in a combined series of experiments, where the autoradiographic and the retrograde degeneration techniques were applied in the same animal.

Cortical Projections of the Pulvinar Nuclear Group of the Thalamus in the Cat; pp. 422–439

Abstract: Localized stereotaxic lesions wereplaced in the pulvinar nuclear group of the cat thalamus, and the ensuing fiber degeneration was traced to the cerebral cortex by the method of Nauta and Gygax. The m

Projections from the striate cortex to the diencephalon in the squirrel monkey (Saimiri sciureus). A light microscopic radioautographic study following intracortical injection of H3 leucine.

Abstract: Tritiated leucine was injected into three different regions of the striate cortex in nine squirrel monkeys and the axoplasmic transport of labelled protein in the neurons was used to identify terminal fields of projection in the thalamus. The regions of injection corresponded to those representing about 3°, 10°, and 30° eccentricity in the contralateral visual field. The periods of post-injection survival were 9–19 hours, 8 days, and 23 days. The exposure was about three weeks in all cases. In the thalamus terminal fields of projection were identified in the lateral geniculate nucleus, the posterior nucleus of the thalamus, the inferior and lateral pulvinar nucleus, the reticular nucleus of the thalamus and the pregeniculate nucleus. In most of the projections the location of the terminal fields varied systematically with the location of the injection site indicating a retinotopic organization. In eight of the nine experiments all of the thalamic projections were observed. In the cases with postinjection survival times of 8 and 23 days pronounced axonal labelling was seen, and the corticothalamic pathway could be traced from the site of injection to the thalamus. In one experiment in which only the superficial layers of the cortex were labelled by the injection no thalamic projection was found.

Recurrent hemichorea following striatal lesions.

Abstract: Hemibalplismus is regularly associated with lesions in the contralateral subthalamic nucleus. In addition, hemichorea, at times violent enough to be called hemiballismus, occurs occasionally as a result of lesions in other sites, including the pallidum, thalamus, cortex, and, most often, the neostriatum, usually on the side opposite the uncontrollable limbs. We describe a patient in whom two distinct episodes of severe left-sided hemichorea were associated with two separate right-sided cerebral lesions, one chiefly in the putamen, the second in the caudate nucleus.

Localization of the “maze memory system” in the white rat

Abstract: Adult albino rats, previously trained on a three-cul maze, sustained bilateral cortical or subcortical lesions and were subsequently tested for retention Those animals showing defective retention suffered damage to either the anterior neocortex, posterior neocortex, cingulate cortex, corpus striatum, hippocampus, septofornix area, thalamus (anterior, lateral, ventromedial, or posterior divisions), posterolateral hypothalamus, mamillary bodies, subthalamus, red nucleus, substantia nigra, central tegmentum, ventral portions of the brainstem reticular formation, or the cerebellum Excellent retention was observed following damage to either the amygdaloid complex, rostral medial forebrain bundle, dorsomedial thalamus, or dorsal midbrain These results, coupled with earlier findings, suggest that the maze habit is dependent upon the activities of three functional blocks of the brain: the first block (brainstem reticular formation) has integrative functions, the second block (sensorimotor cortex, cingulate cortex, cerebellum, and thalamus) has kinesthetic functions, and the third block (occipital cortex, hippocampus, septofornix area, and mamillary bodies) plays a role in the discrimination of spatial cues

Behavioral effect of intracerebrally injected carbachol on unrestrained cats.

Abstract: The rage reaction which can be evoked by carbachol stimulation of the hypothalamus on freely moving cat is not specific for the hypothalamus by far. It can also be elicited by carbachol stimulation of the septal region, thalamus (intralaminary nuclei), central grey matter, red nucleus, mesencephalic reticular formation as well as by injecting the drug into the cerebral ventricle. No rage reaction can be evoked by carbachol stimulation of the globus pallidus, putamen, dorsal hippocampus, ventral hippocampus, anterior, basal, central or lateral amygdaloid nucleus and the cerebral white matter. The significance of these findings is discussed.

Neural pathways from thalamus associated with regulation of aggressive behavior.

Abstract: Small electrolytic lesions were made through electrodes in the thalamus of cats at sites where electrical stimulation elicited attack on a rat. Staining by modified Nauta reduced silver methods revealed that significant degeneration passed caudally from the lesions and entered the midbrain dorsal central gray region. Electrical stimulation of this dorsal midbrain region elicited attack on a rat, and destruction of this region suppressed the attack elicited by thalamic stimulation.

Extensive developmental defect of the cerebellum associated with posterior fossa ventriculocele.

Abstract: 1. A case is described in which an extensive cerebellar cortical defect with modification of collateral roof and brain stem nuclei, periventricular leukomalacia in the cerebral hemispheres, and an anomalous midline thalamic fusion were associated in a neonate with severe hydrocephalus and a massive rhombie roof ventriculocele. 2. The positional interrelationships of the principal types of neurons in the defective cerebellar cortex were normal, implying that the pathologic process intercepted normal development after the 5th fetal month. The cytoarchitectonic and topographic features of collaterally modified nuclear structures and the quality of histopathologic reaction were consistent with this inference. 3. The topographic distribution of the cortical defect is most plausibly explained by perfusion failure in the end fields of perfusion of the principal cerebellar arteries. It is suggested that this perfusion failure was due to compression or torsion of arteries by the massive ventriculocele. Hydrocephalic force with mural compression and ischemia probably accounted for the leukomalacia in the cerebral hemispheres. Hydrocephalus may have played a role in the abnormal thalamic fusion via diencephalic compression. 4. The hydrocephalus appeared to have resulted from obstruction to CSF circulation at the level of the roofing membrane of the 4th ventricle. The ventriculocele was a massive hydrocephalic expansion of this membrane. The cause of the hydrocephalus was obscure. The outflow foramina were not patent but not internal morphological evidence bears upon whether or not the hydrocephalus antedated the normal opening of the foramina.

Structure and Fiber Connections of the Hypothalamus in Mammals

Abstract: Publisher Summary This chapter is a survey of the structure and fiber connections of the mammalian hypothalamus. Particular attention is paid to the anatomical techniques that are exploited in the experimental tracing of pathways in the central nervous system. The hypothalamus in the mammalian brain encompasses the most ventral part of the diencephalon where it forms the floor and, in parts, the walls of the third ventricle. Its upper boundary is marked by a sulcus in the ventricular wall: the ventral diencephalic or hypothalamic sulcus. This sulcus separates the hypothalamus from the dorsally located thalamus. Caudally, the hypothalamus merges without any clear demarcation with the periventricular gray and the tegmentum of the mesencephalon. Rostrally the hypothalamus is continuous with the preoptic area, which lies partly forward to and above the optic chiasma. Although it is still in dispute whether the preoptic area is of telencephalic origin or has to be considered part of the diencephalon, the similarities in histological structure and fiber connections seem to justify the concept that this area is a rostral continuation of the hypothalamus.