Showing papers on "Thalamus published in 1975"
TL;DR: The projection of cells in different layers of several cortical visual areas in the cat were studied using the method of retrograde transport of horseradish peroxidase, indicating a remarkable specificity in the projections of the cortical layers.
Abstract: The projection of cells in different layers of several cortical visual areas in the cat were studied using the method of retrograde transport of horseradish peroxidase. Injections of the enzyme were made through a recording micropipette, making it possible to localize the injection site by physiological criteria. We found that layer VI cells projected to the alteral geniculate nucleus, while a distinct population of cells in layer V projected to the superior colliculus. Cells in layers II and III were tha major sources of ipsilateral cortico-cortical connections. This pattern of projection was consistent from one visual area to another. Pyramidal cells appeared to be the source of cortico-geniculate, cortico-collicular and cortico-cortical projections. The proportion of cells within a layer that terminated in a given site varied from layer to layer: apparently all of the large pyramids in layer V had terminals in the superior colliculus, about half of the pyramids in layer VI had terminals in the lateral geniculate nucleus, while only a small proportion of the pyramids in layers II and III had terminals in any single cortical area. The results indicated a remarkable specificity in the projections of the cortical layers. The cortical connections of the different cell types in layers A and A1 of the lateral geniculate nucleus were also examined: the cells that projected to area 17 were much more numerous and were on the average smaller than those that projected to area 18. Projections to the cortex were also found from the pulvinar, the medial interlaminar nucleus and the posterior nucleus. Direct connections were observed to the lateral geniculate nucleus from several midbrain reticular nuclei. Finally, projections were found to the superior colliculus from the zona incerta, the reticular nucleus of the thalamus and the ventral lateral geniculate nucleus.
702 citations
TL;DR: These new findings demonstrate that these frontal and parietal cortex areas receive direct afferent fibers from limbic basal forebrain areas concerned with emotion and motivation.
Abstract: Horseradish peroxidase was injected in different parts of the frontal and parietal cortex in 17 rhesus monkeys. In all cases the enzyme was transported retrogradely to neurons in the substantia innominata and hypothalamus as well as in the thalamus. These new findings demonstrate that these cortical areas receive direct afferent fibers from limbic basal forebrain areas concerned with emotion and motivation.
368 citations
TL;DR: Electrophysiological investigation of the pontine taste area proves that gustatory information from two distinct receptive fields may converge on the same central neuron.
299 citations
TL;DR: An autoradiographic study of the subcortical projections of the rat hippocampal formation shows that the efferent fibers of the hippocampus proper do not project to the hypothalamus but are confined to the precommissural fornix, ending primarily in the septum.
Abstract: An autoradiographic study of the subcortical projections of the rat hippocampal formation shows that the efferent fibers of the hippocampus proper (fields CA1-4 OF Ammon's horn) do not project to the hypothalamus but are confined to the precommissural fornix, ending primarily in the septum. The fibers that are distributed by way of the fornix system to the hypothalamus (principally the arcuate-ventromedial region and the mammillary nuclei) and the anterior thalamus arise from the subicular region of the cerebral cortex (that is, the subiculum, presubiculum, and parasubiculum).
294 citations
TL;DR: From a series of lesions and in vitro uptake studies, evidence has been obtained that the incerto-hypothalamic fibres are the projections of short, intradiencephalic dopaminergic neurones whose cell bodies are located in the A11, A13 and A14 cell groups.
291 citations
TL;DR: It was concluded that there exists an olfactory pathway from the OB to the LPOF through the AP (and probably the MA) and the hypothalamus, but none through the thalamus, and that the L POF plays an important role in the discrimination of odors.
Abstract: An olfactory projection area was studied in monkeys anesthetized with Nembutal. 1. Evoked potentials were recorded when the olfactory bulb (OB) was electrically stimulated in the lateroposterior portion of the orbitofrontal cortex (LPOF). However, those potentials disappeared when the anterior pyriform cortex (AP) (probably together with the medial portion of the amygdala (MA)) was aspirated or electrically destroyed. 2. In nearly the entire hypothalamic region, evoked potentials were recorded by the same stimulation of the OB. When the hypothalamic region was stimulated, evoked potentials were recorded in the LPOF. 3. The evoked potentials in the LPOF due to the OB stimulation never disappeared even when the thalamus was extensively aspirated or destroyed electrically, but they did disappear when the anterolateral and dorsoposterior portions of the hypothalamus were absorbed or electrocoagulated. 4. Evoked potentials in the mediodorsal nucleus (MD) of the thalamus were recorded when the OB was stimulated. When this nucleus was stimulated, evoked potentials were observed in the broad extent of the orbitofrontal cortex anterior to the LPOF, but never in the LPOF itself. 5. Monkeys were conditioned to discriminate two odors. When the LPOF was removed, such ability strikingly decreased; but when other areas in the prefrontal cortex were removed, the ability decreased only slightly. 6. It was concluded that there exists an olfactory pathway from the OB to the LPOF through the AP (and probably the MA) and the hypothalamus, but none through the thalamus, and that the LPOF plays an important role in the discrimination of odors. 7. It was proved that the entorhinal cortex (ER) is neither located as an intermediate olfactory area nor is it situated as a higher area than the LPOF in the newly found olfactory pathway stated above. It may be a link between the high olfactory area and the limbic system.
213 citations
TL;DR: The structure of the first somatic sensory area, of the motor area and the intervening transitional field is described in the squirrel monkey using Nissl, Bodian, Weil and Golgi preparations and the laminar arrangement of both cells and axons is briefly described.
Abstract: The structure of the first somatic sensory area (areas 3, 1 and 2), of the motor area (area 4) and the intervening transitional field (area 3a) is described in the squirrel monkey (Saimiri sciureus) using Nissl, Bodian, Weil and Golgi preparations. The laminar arrangement of both cells and axons is briefly described and this correlated with the distribution of thalamic afferents as identified in experiments conducted with the Nauta and autoradiographic techniques. The latter method was used particularly in order to assess quantitative differences in the density of thalamic projections to the five cytoarchitectonic fields. In the somatic sensory areas thalamic afferents terminate not only in layer IV but a large extent also in a recognizable part of layer III (layer IIIb). In area 4 thalamic terminals fill much of layer III, reaching almost to layer II. In area 3a the extent is intermediate between that seen in areas 3 and 4. It is thought that the extensive spread of thalamic terminals is related to the elongated form of a particular class of spine-bearing cell whose somata are situated in layer IV (Jones, '75). In all areas a small proportion of thalamic afferents end also in layer I. Evidence is presented to indicate that specific afferent fibers emanating from the ventrobasal and ventrolateral complexes of the thalamus terminate in both the deep and superficial parts of layer I while "non-specific" afferents from other thalamic sources end in the superficial part. The autoradiographic studies indicate that there are considerable differences between the number of thalamic afferents ending in area 3 on the one hand and in areas 1 and 2 on the other. Given this and the nature of the degenerating thalamic afferents observed in Nauta preparations, it is possible to identify thalamic afferents in normal Golgi preparations and significant differences are detectable in areas 4, 3 and 1 and 2. It it is as yet uncertain whether the slightly thinner, more sparsely distributed thalamic afferents ending in areas 1 and 2 are branches of those directed primarily to area 3.
207 citations
TL;DR: The ascending degeneration resulting from experimental lesions of the ventral funiculus of the spinal cord of Macaca mulatta has been studied using the Nauta technique and its variants.
Abstract: The ascending degeneration resulting from experimental lesions of the ventral funiculus of the spinal cord of Macaca mulatta has been studied using the Nauta technique and its variants. The ventral spinothalamic tract is shown to be an independent entity with respect to the lateral spinothalamic tract; its fibers are widely distributed in the ventral funiculus and it establishes connections with the brain stem and thalamus which are analogous but not identical to those of the latter. Its role in the relay of nociceptive input is discussed in view of the similarity in hodology of the two systems and it is proposed that it may be responsible for the failure of anterolateral cordotomy to control pain on a long term basis. Other ascending systems in the ventral funiculus include the spino-olivary and spino-reticular tracts, as well as minor connections to the N. of Edinger-Westphal, the red nucleus and the superior colliculus. The projections from the ventral quadrant of the spinal cord to the brain stem are almost entirely ipsilateral until the rostral mesencephalon is reached, at which level the N. of Darkschewitz receives both ipsilateral and crossed input; the magnocellular nucleus of the medial geniculate body receives a small contribution which is mainly ipsilateral. In the thalamus the VPL receives predominantly ipsilateral projections while the input to the paralaminar nuclei is only slightly less pronounced contralaterally than ipsilaterally.
164 citations
TL;DR: The data derived from the rats which had received thalamic injections of HRP and [3H]leucine in combination indicated that the connections between cortex and thalamus are in general reciprocal.
116 citations
110 citations
TL;DR: The present study analyzed the connections of the pulvinar nucleus in a prosimian in Galago to see how this primate organization, if indeed the Galago is representative of primates, evolved from the organization reflected in Tupaia.
Abstract: The present study was undertaken to analyze the connections of the pulvinar nucleus in a prosimian. The experiments, which rely on the Fink-Heimer ('67) method for staining degenerating axons and their terminals, fall into two parts: first, the tracing of ascending tectal projections to the caudal thalamus and second, the tracing of projections from this thalamic target to the cortex. Large lesions of the superior colliculus resulted in dense degeneration in the caudal half of the inferior subdivision of the pulvinar complex. This pathway could be identified when the lesion was restricted to the superficial layers of the superior colliculus, signifying that it is a visual pathway. In general, the projections of the deep and superficial layers of the superior colliculus were distinct and in this respect Galago resembles Tupaia. The inferior pulvinar nucleus in turn projects to area MT, a conspicuous subdivision of the temporal cortex. The superior division of the pulvinar, in contrast to the inferior division, is not a major target of ascending projections from the superior colliculus and projects to the areas of the occipital and temporal lobe intercalated between areas MT and 17. When these results are compared with similar studies in nonprimates, notably studies of Tupaia, a striking difference in organization emerges. In Tupaia, and in distantly related mammals such as the squirrel, the target of the tecto-pulvinar system includes area 18 adjacent to area 17. This feature is important since the two parallel projection systems seem to be related to each other in terms of the way in which the zero vertical meridian is spatially represented. However, in Galago the subdivision of the pulvinar receiving projections arising from the superior colliculus does not project to area 18. Area 18 is indeed the target of pulvinar projections, but these projections arise from that portion of the pulvinar which is not a recipient of ascending tectal projections. It is not easy to see how this primate organization, if indeed the Galago is representative of primates, evolved from the organization reflected in Tupais.
TL;DR: Visceral afferent input can be relayed to the thalamus via direct spinal projections, and convergence of visceral and cutaneous input onto spinothalamic tract cells may play a role in the phenomenon of referred pain.
TL;DR: The integrative level of the preoperative brain is a significant variable in predicting the presence or absence, and degree of post-operative verbal alterations.
TL;DR: Recruiting responses and related synchronous activities appear to be mediated by thalamic inhibition originating in nucleus reticularis thalami, a structure jointly regulated by an ascending projection from mesencephalic reticular formation and a descending influence from the frontal cortex.
TL;DR: The retrograde transport of horseradish peroxidase (HRP) has been used for the present study and provides anatomical evidence of a DCN‐cerebellar pathway.
Abstract: The existence of a cerebellar projection from the dorsal column nuclei (gracile and cuneate nuclei, DCN) has been proposed on electrophysiological grounds but questioned when studied with neuroanatomical techniques. The retrograde transport of horseradish peroxidase (HRP) has been used for the present study and provides anatomical evidence of a DCN-cerebellar pathway. In adult cats, 1 to 6 μl of 30% HRP were injected in pars intermedia of the anterior lobe (lobules IV–V), in paramedial lobule and in vermis of the anterior (lobules IV–V) and of the posterior lobe (lobule VII). After survival of 24 to 48 hours, all animals were perfused with a double aldehyde mixture and serial 40 μ sections through the medulla oblongata were incubated for visualization of HRP. In all cases, medullary nuclei known to project to the injected cortical regions of the cerebellum contained HRP-positive neurons mainly ipsilateral to the injection (e.g., external cuneate nucleus) or mainly contralateral to it (e.g., inferior olivary complex).
Following ipsilateral injections in either the paramedian lobule or the pars intermedia, HRP-positive neurons in the cuneate nucleus were concentrated in its rostral portion where multipolar cells with radiating dendrites predominate. In contrast, none of the cells of the clusters region, in the caudal part of the cuneate nucleus, displayed HRP-positive granules. In cases in which the anterior vermis was injected a few labelled cells were present in the rostral part of the gracile nucleus but not in the clusters region of this nucleus. No labelling of DCN neurons was evident after posterior vermis injection.
To compare the distribution of cells contributing to the DCN-cerebellar pathway with that of thalamic relay cells in the DCN, 0.5 to 3 μl of 30% HRP were injected in the nucleus ventralis posterolateralis of the thalamus in another series of cats. Contralateral to the thalamic injection, labelled cells were concentrated in the clusters region of the gracile and cuneate but rostrally in these nuclei they were scattered among unlabelled neurons.
The preferential location in the DCN of cells which project to the cerebellum and of cells which project to the thalamus stresses the heterogeneous organization of these nuclei along the rostrocaudal axis. Further, the results indicate that regions of the DCN which have been distinguished on the basis of cytoarchitectonics (Kuypers and Tuerk, '64) and of afferents (Rustioni, '73, '74) differ also in their efferent projections.
TL;DR: It is proposed that degeneration of the thalamic nuclei receiving striatal efferents appears to remove an essential modulating influence on the corticospinal system which can only become manifest if this system is relatively preserved.
Abstract: Disorders of movement after hemiplegia have been described for more than a century, but their pathological anatomy and physiology have remained poorly understood because of ambiguous terminology and incomplete studies. We examined the brains of 5 patients which had been serially sectioned where there had been well documented pure motor hemiplegia acquired in childhood. In 4 patients handicapped by hemiathetosis the main lesion was partial destruction of the caudate nucleus and putamen. In the fifth case, where non-disabling involuntary movements only appeared in later life, there was gliosis of the caudate nucleus and thalamus. Striatal lesions produce involuntary movement disorders if the corticospinal and other major motor tracts are partly intact. We propose that degeneration of the thalamic nuclei receiving striatal efferents (ventralis anterior, ventralis lateralis and centrum medianum), wheter primary or secondary, appears to remove an essential modulating influence on the corticospinal system which can only become manifest if this system is relatively preserved.
TL;DR: It is proposed that the retino-anterior thalamic-retrosplenial circuit forms an anatomical substrate by which light cues may affect emotional behavior and corresponding neurovisceral responses.
Abstract: Evidence for a direct projection from the retina to the nucleus anterodorsalis thalami in the insectivore, Tupaia glis, is presented. 100 μCi tritiated amino acid or amino acid/monosaccharide cocktail were administered as two separate intravitreal injections of 50 μCi each. Fibers were traced using thawmount autoradiography in which tissue is frozen in liquid propane, cryostat-cut, and mounted on photographic emulsion precoated slides (Conrad and Stumpf, 1974). From the dorsolateral geniculate body, contralateral retinal fibers continue as a dorsomedial extension of the optic tract. When traced rostrally from this point, the fibers form a thin fascicle coursing medially under the third ventricle. In the anterior thalamus the bundle arborizes within the n. anterodorsalis, infiltrating its caudal pole completely but only encapsulating the nucleus anteriorly. This new retino-anterodorsal thalamic projection, together with the known anterior thalamic-retrosplenial projection, represents a third visual pathway in Tupaia glis distinct from the retino-geniculo-striatal and retino-tecto-pulvinarperistriatal systems. It is significant that each of these thalamic relay nuclei projects to an architectonically different cortical region, with the nucleus anterodorsalis sending afferents to the phylogenetically most primitive of the visual cortices, the retrosplenial proisocortex or prostriata (Vitzthum and Sanides, 1967). It is proposed that the retino-anterior thalamic-retrosplenial circuit forms an anatomical substrate by which light cues may affect emotional behavior and corresponding neurovisceral responses.
TL;DR: An asymmetry in the functional organization of linguistic and nonverbal processes appears to exist at the level of the lateral thalamus, suggesting that the pulvinar scans incoming sensory traces and searches long-term memory registers for appropriate cues and labels.
TL;DR: Unilateral partial ablations were made in the orbitofrontal cortex of 4 adult marmosets and fiber degeneration was traced using the Nauta-Gygax and Fink-Heimer selective silver impregnation techniques, and the possibility of a topical organization in the orbital cortical and thalamic projections is discussed.
TL;DR: It was concluded that the efferent impulses originating from the cerebellar nuclei can produce contraction of a particular muscle through activation of the red nucleus.
TL;DR: The marginal zone of the spinal cord appears to project to at least two of the thalamic regions receiving spinothalamic fibres in the monkey.
TL;DR: The efferents to posterior parietal cortex suggest the possibility of an area for the integration of somatosensory and visual information and support the notion that visual association cortex consists of a number of separate, but complexly interrelated, subdivisions.
Abstract: The efferent subcortical connections of the dorsomedial cortical visual area (DM) in the owl monkey were determined by tracing degenerating axons following lesions or by tracing axonal pathways following injection of radioactively labeled proline. Areas of termination included structures which are known to receive input from many other regions of cortex such as the claustrum, putamen, caudate nucleus, reticular nucleus of the thalamus and pontine nuclei. Other terminations were in subcortical structures which primarily receive input from visual areas: these included the pregeniculate nucleus, the medial and central divisions of the inferior pulvinar nucleus, two loci in the superior pulvinar complex, the pretectum and the superior colliculus. Terminations were also seen in the lateral posterior nucleus, a part of the thalamus associated with the somatosensory system. These results further identify Area DM as an integral part of the visual system, suggest functional subdivisions of the pulvinar complex, and implicate the lateral posterior nucleus in the mediation of visual, as well as somatosensory, behavior.
TL;DR: The results of this study suggest that a sperm release system in the green sunfish extends from the preoptic area to the spinal cord passing through the hypothalamus, midbrain tegmentum and basal midbrain and medulla.
Abstract: Acute brain stimulation experiments were carried out in anesthetized male green sunfish, Lepomis cyanellus. Semen discharge was evoked consistently by low level electrical stimulation (100 muA or less) in the following areas: the preoptic region, dorsal hypothalamus, thalamus, midbrain tegmentum and the basolateral midbrain and medulla. Areas which were stimulated repeatedly at 100 muA and were always negative for sperm release included: the telencephalon with the exception of the preoptic region, the optic tectum, the cerebellum, the inferior lobe of the hypothalamus, the nucleus rotundus and the dorsal medulla. Removal of most of the optic tectum and cerebellum failed to block reponses evoked from the preoptic area; however, they were usually eliminated by transecting the rostral spinal cord. Electrical stimulation of an isolated 4 mm segment of spinal cord located at the third vertebral level resulted in sperm release, indicating that adequate mechanisms for semen discharge are present within the upper spinal cord. The results of this study suggest that a sperm release system in the green sunfish extends from the preoptic area to the spinal cord passing through the hypothalamus, midbrain tegmentum and basal midbrain and medulla.
TL;DR: In the present study total or partial unilateral stereotaxic lesions of PrV were made in cebus and rhesus monkeys and analyzed with the aid of a variety of Nauta silver impregnation techniques applied to frozen sections.
Abstract: To date, anatomical studies of ascending principal sensory trigeminal nuclear (PrV) axons in the monkey have been restricted to few incomplete investigations utilizing the Marchi method. In the present study total or partial unilateral stereotaxic lesions of PrV were made in cebus and rhesus monkeys and analyzed with the aid of a variety of Nauta silver impregnation techniques applied to frozen sections.
Analysis of the fiber degeneration emanating from PrV lesions indicates that PrV fibers from an ascending system composed of two distinct components. Most PrV axons project ventromedially from PrV through the ventral pontine tegmentum and gradually decussate across the midline in the mesencephalic tegmentum up to the level of the caudal pole of nucleus interpeduncularis. These decussated fibers form the trigeminal lemniscus, which courses dorsomedial to the medial lemniscus during its ascent into the diencephalon. A few whorls of preterminal fiber degeneration separating from the trigeminal lemniscus first appear in the magnocellular area of the thalamus medial to the medial geniculate body. The lemniscal PrV axons terminate densely throughout most, but not all, of the magnocellular part of nucleus ventralis posteromedialis (VPM) contralateral to the side of their origin. Some collateral-like fibers from the trigeminal lemniscus also were observed ending in the ventral segment of the zona incerta. Other axons, arising chiefly from the dorsal one-third of PrV, form a smaller ipsilateral trigeminothalamic projection. These fibers all remain on the side of their origin and terminate consistently in a discrete dorsomedial paralaminar portion of VPM that does not receive lemniscal PrV connections.
A commissural fiber system at the pontine level connects parvicellular reticular cells with their counterparts and the motor trigeminal nucleus of the opposite side. These interconnections appear to provide an anatomical link for the integration of bilateral trigeminal sensory information and motor function.
TL;DR: Physiologically guided stereotaxic coagulation was placed so as to avoid major through pathways in the midbrain reticular formation of 7 cats, and preterminal degeneration was found in: the intralaminar nuclei and the posterior group (PO); the ventral group of thalamic nuclei; theventral thalamus; and the lateral hypothalamus.
TL;DR: This autoradiographic study demonstrates a topical projection of the dorsal column nuclei to the contralateral nucleus ventralis posterior lateralis thalami and the accessory part of the inferior olive.
Abstract: This autoradiographic study demonstrates a topical projection of the dorsal column nuclei to the contralateral nucleus ventralis posterior lateralis thalami and the accessory part of the inferior olive In contrast to earlier anatomical studies the projections of the gracile nucleus and the internal cuneate nucleus proved to be independent and entirely contralateral
Fibers from the gracile nucleus terminate only in the lateral part of the nucleus ventralis posterior lateralis (VPL1) and from the internal cuneate nucleus only in the medial part of this nucleus (VPLm) Projections of the gracile nucleus to the contralateral inferior olive are restricted to the caudal one-third of the medial accessory olive and the ventrolateral part of the dorsal accessory olive The internal cuneate nucleus is only connected with the dorsomedial part of the rostral two-thirds of the dorsal accessory olive
Our material does not allow conclusions about projections from the dorsal column nuclei to other thalamic nuclei and about rostrocaudal point to point relationships between the dorsal column nuclei and the thalamus or the inferior olive
TL;DR: The ascending projections of the dorsolateral funiculus of the spinal cord to the brain stem and the medulla have been determined in five macaque monkeys.
Abstract: The ascending projections of the dorsolateral funiculus of the spinal cord to the brain stem have been determined in five macaque monkeys. Connections to the lateral cervical nucleus and to the reticular nucleus of the cord in the C1 and C2 segments are present. In the medulla the most prominent connections are to the nuclei "Z" and "x" of Brodal and Pompeiano, to the rostral portion of n. gracilis and to the n. proprius of the restiform body. Minor projections reach the rostral part of the medial and lateral cuneate nuclei, the reticular nucleus, the n. centralis dorsalis and the periependymal gray. There were no projections to planes rostral to the medulla. In view of the connections established it is concluded that ascending systems in the DLF to the brain stem of primates are concerned with transmission of mechanoreceptor input to the cerebellum and thalamus and that nociceptive relay appears very unlikely.
TL;DR: It was demonstrated morphologically that nerve cells in the rostrodorsal areas of the complex of the anterior ventral and lateral ventral nuclei, the posterior lateral nucleus and the lateral central nucleus of the thalamus in the cat send axons to rostral portions of the middle suprasylvian gyrus.