Showing papers on "Thalamus published in 1972"
TL;DR: The problem of the stria terminalis projection field has been examined by use of two versions of the cupric‐silver technique as well as variations of the Fink‐Heimer and Nauta‐Gygax techniques applied to material fixed under different conditions using brains from very young rats surviving 30 hours to four days after production of lesions.
Abstract: The problem of the stria terminalis projection field has been examined by use of two versions of the cupric-silver technique as well as variations of the Fink-Heimer and Nauta-Gygax techniques applied to material fixed under different conditions using brains from very young rats surviving 30 hours to four days after production of lesions at different levels of the course of the stria terminalis and related structures. The findings are as follows:
(1)
A dorsal subventricular portion of the stria terminalis divides into retrocommissural and supracommissural contingents which together account for degenerating terminals seen in the ipsilateral bed nuclei of the stria terminalis and of the anterior commissure, and in the medial preoptic-hypothalamic junction area. The supracommissural bundle also disseminates into the laterobasal septum, nucleus accumbens, olfactory tubercle, the posterior and medial divisions of the anterior olfactory nucleus, and the granular layer of the accessory olfactory bulb. Additional fibers end in the paucicellular capsule of the ventromedial hypothalamic nucleus, also in a small lateral parvocellular tuberal nuclear area, and throughout the premammillary nuclei. A small truly commissural division of the dorsal component was traced to the contralateral cortical amygdaloid nucleus and to small clusters of medial amygdaloid cells.
(2)
A ventral juxtacapsular portion of the stria terminalis was traced to the ipsilateral strial bed nucleus, medial preoptic-hypothalamic junction area, the entire ventromedial hypothalamic nucleus, the lateral tuberal area and the premammillary nuclei. The lateralmost fibers of the dorsal strial component as well as those of the ventral component which lie lateral to the “commissural bundle” appear to terminate exclusively in the lateral portions of the bed nucleus of the stria.
(3)
A “commissural bundle” or component, after crossing the midline in the anterior commissure, ends in the bed nucleus of the posterior limb of the latter, in the olfactory tubercle, prepiriform cortex, lateral amygdaloid nucleus and the strial bed nucleus. It is thus a decussation rather than a commissure. No contribution from stria terminalis to stria medullaris could be identified.
349 citations
TL;DR: Thalamic projections to the medial cortex (cingulate cortex and presubiculum) were studied by the use of anterograde degeneration methods and observations made in rats with various lesions of the anterio.
Abstract: Thalamic projections to the medial cortex (cingulate cortex and presubiculum) were studied by the use of anterograde degeneration methods. Observations made in rats with various lesions of the anterio
227 citations
TL;DR: The connections of the mediodorsal nucleus were compared in rats, cats and monkeys and the paralamellar portion received from the cerebellum, superior colliculus and spinal cord and projects to the medial frontal area in rats and area 8 in monkeys.
Abstract: The connections of the mediodorsal nucleus were compared in rats, cats and monkeys. The medial portion receives from the olfactory cortex in rats, amygdala in cats, and amygdala and inferior temporal cortex in monkeys. In turn, the medial portion projects to sulcal cortex dorsal to the rhinal fissure in rats, and to orbitofrontal cortex in monkeys. The paralamellar portion of the mediodorsal nucleus receives from the cerebellum, superior colliculus and spinal cord and projects to the medial frontal area in rats and area 8 in monkeys. The lateral portion of the mediodorsal nucleus, well developed in monkeys, receives no known projections from subcortical regions and projects to the convexity of the frontal lobe.
192 citations
TL;DR: The findings suggest that the posterior association cortex of the cat's hemisphere may be divided into proximal association cortex, including circumsensory rim-areas, and distal association cortex comprising much of the crown of the suprasylvian gyrus.
191 citations
TL;DR: Some afferent and efferent connections of the posterior thalamic region have been studied in the cat by means of anterograde degeneration methods and the organization of these connections is discussed with the aid of a more general framework.
Abstract: Some afferent and efferent connections of theposterior thalamic region have been studied in the cat by means of anterograde degeneration methods. The organization of these connections is discussed with the aid of a more general framework that interprets each of a variety of ascending sensory channels as comprising lemniscal line system or lemniscal adjunct channels and that distinguishes within the posterior convexity cortex (1) sensory cortex, (2) proximal association cortex and (3) distal association cortex.
160 citations
TL;DR: The retinal projections of a teleost fish are studied using the Nauta-Gygax and Fink-Heimer methods following unilateral eye enucleation to reveal totally crossed projections to a small magnocellular nucleus of the hypothalamus.
155 citations
TL;DR: The significance of axonal branches in maintaining the integrity of the neuronal soma after axon section has been studied in the lateral mammillary nucleus (LMN) of the cat.
Abstract: The significance of axonal branches in maintaining the integrity of the neuronal soma after axon section has been studied in the lateral mammillary nucleus (LMN) of the cat. Earlier studies with the Golgi and reduced silver methods have shown that the axons of most, if not all, of the cells of this nucleus which enter the principal mammillary tract (PMT) bifurcate with one branch entering the mammillo-thalamic tract (MThT) and the other the mammillo-tegmental tract (MTgT). Some of the fibers in the MThT may again bifurcate before ending bilaterally in the anterodorsal nucleus of the thalamus (AD).
Unilateral destruction of the AD results in no detectable retrograde cell degeneration in the LMN. Lesions of the MThT (below the interanteromedial nucleus) cause a slight (∼ 15%) cell loss in the LMN, while isolated lesions of the MTgT have no detectable effect upon the cells of the nucleus. Combined lesions of the MThT and the MTgT cause severe retrograde degeneration in the LMN: approximately 60% of the cells disappear and many of the surviving neurons are frankly atrophic. Lesions of the PMT involving the parent axons of the cells in the LMN result in about the same degree of cell loss as combined lesions of the MThT and MTgT, but the persisting neurons are more severely shrunken and pyknotic.
The implications of these findings for the organization of the connections of the LMN and for the interpretation of retrograde cell degeneration are discussed.
146 citations
TL;DR: The almost complete absence of degenerating boutons in the lateral hypothalamus contrasts sharply with the abundance of terminal degeneration in extrahypothalamic regions such as the mediodorsal nucleus of the thalamus (MD), the anterior continuation of hippocampus, the olfactory tubercle and the fundus striati.
Abstract: The distribution of denegerating axons following heat lesions in different parts of the olfactory cortex in the rat was studied with light- and electron-microscopic techniques. The almost complete absence of degenerating boutons in the lateral hypothalamus contrasts sharply with the abundance of terminal degeneration in extrahypothalamic regions such as the mediodorsal nucleus of the thalamus (MD), the anterior continuation of hippocampus, the olfactory tubercle and the fundus striati. The only part of the lateral hypothalamus that seems to receive a sizeable amount of fibers direct from olfactory cortex is the nuclei gemini. The olfactory projections of the thalamus seem to be related primarily to the medial subdivision of the MD. Although a significant number of fibers in the olfactory projection system join the stria medullaris in the anterolateral hypothalamus, they leave the stria at the level of the habenular complex to terminate in MD instead of the lateral habenular nucleus.
143 citations
TL;DR: Electrical stimulation was applied through a concentric bipolar electrode in the area of entry of the medial lemniscus into the thalamus to produce antidromic volleys in axons of spinothalamic tract neurons in cats to determine the location of antidromically activated cells.
136 citations
TL;DR: Although their thalamocortical projections and correlated behavioral states are relatively discrete, their functional origins both appear to reside in a mechanism concerned with the specific suppression of phasic motor activity.
TL;DR: Thalamic projections to the visual cortex of the grey squirrel were studied by retrograde degeneration in the lateral geniculate and the pulvinar nuclei to form a conception of those changes in the visual system which arose as a result of adaptation to an arboreal habitat.
Abstract: Thalamic projections to the visual cortex of the grey squirrel were studied by retrograde degeneration in the lateral geniculate and the pulvinar nuclei. The lateral geniculate was found to project to architectonic area 17 which also corresponds to visual area I as defined by its retinotopic organization. The projection is spatially organized in a precise way, and for every cortical point there is a corresponding column in the lateral geniculate which extends from border to border. For the binocular sector of area 17 the lateral geniculate column lies in the trilaminar part of the lateral geniculate, while for the uniocular sector the column lies in the bilaminar sector of the lateral geniculate. The pulvinar projects to several architectonic areas, areas 18 and 19 and to two or more temporal areas below area 19. This projection is roughly topographic but follows the sustaining pattern. When the squirrel is compared to the tree shrew and hedgehog what emerges is a conception of those changes in the visual system which arose as a result of adaptation to an arboreal habitat.
TL;DR: Electron microscopic examination shows that parts of two different populations of synaptic terminals degenerate as a result of the cortical lesions: the RS terminal which rapidly becomes electron‐dense and later is phagocytosed, and the RL terminal, which initially exhibits signs of neurofilamentous hyperplasia and later becomes electron-dense.
Abstract: The synaptic morphology of the pulvinar has been examined following cortical lesions in peristriate, posterior temporal and posterior parietal areas. Light-microscopic stains demonstrate orthograde degeneration in p. lateralis, p. inferior, and the posterior nucleus, with a convergent input to the medial one-half of p. inferior and the posterior nucleus. Electron microscopic examination shows that parts of two different populations of synaptic terminals degenerate as a result of the cortical lesions: the RS terminal, which rapidly becomes electron-dense and later is phagocytosed, and the RL terminal, which initially exhibits signs of neurofilamentous hyperplasia and later becomes electron-dense.
Comparisons are made between the pulvinar and other thalamic nuclei with respect to synaptic organization and the origin of extrinsic synaptic terminals. It is pointed out that while the overall arrangements within the pulvinar are equivalent to those in VB, MGB or dLGN, the fact that two different populations of synaptic terminals originate in the cortex suggests functional differences between the pulvinar and other parts of the thalamus examined thus far. The possible phylogenetic origins of different parts of the pulvinar are also discussed.
TL;DR: Comparison between laminar field potentials in the same cortex produced by thalamic and cerebellar nucleus stimulation suggests that the response in the pericruciate cortex is mediated by the ventral lateral nucleus and that theresponse in the parietal cortex is relayed by the Ventral anterior nucleus of the thalamus.
Abstract: 1.
Cerebello-cerebral projections were electrophysiologically investigated in cats under light Nembutal anaesthesia. Marked responses were produced by stimulation of the interpositus and the lateral nucleus of the cerebellum not only in the pericruciate but also in the suprasylvian cortical areas, both areas being contralateral to the cerebellar nuclei stimulated. Medial nucleus stimulation set up little or no response in the cerebral cortex.
2.
The previous electrophysiological study on thalamo-cortical (T-C) projections showed two different kinds of responses in the cortex due presumably to two different T-C projection systems, i. e., deep and superficial T-C responses (see Sasaki et al., 1970). According to laminar field potential analysis, the response in the pericruciate area is characterized by a deep T-C response which is often followed by a superficial T-C response, whereas the response in the parietal cortex consists of a pure superficial T-C response. Intracellular potential changes in cortical neurones elicited by cerebellar nucleus stimulation were consistent with the results of laminar field potential analysis.
3.
Comparison between laminar field potentials in the same cortex produced by thalamic and cerebellar nucleus stimulation suggests that the response in the pericruciate cortex is mediated by the ventral lateral nucleus and that the response in the parietal cortex is relayed by the ventral anterior nucleus of the thalamus.
TL;DR: In this article, the effect of stereotaxic lesions of the ventral anterior thalamus or the adjacent inferior thalamic peduncle on experimental models of focal cortical epilepsy was studied.
TL;DR: There are two distinct types of thalamocortical projections to parietal cortex in the opossum and the hedgehog which arise from the posterior portion of the ventral nuclear group of the dorsal thalamus which may be subdivided into two nuclei.
Abstract: There are two distinct types of thalamocortical projections to parietal cortex in the opossum and the hedgehog. Both projections arise from the posterior portion of the ventral nuclear group of the dorsal thalamus which may be subdivided into two nuclei. First, the ventral posterior nucleus which receives a homogenous somatic sensory input and projects in a restricted fashion to layer IV of parietal cortex. Second, the central intralaminar nucleus which receives a heterogenous input from somatic sensory nuclei, the cerebellum and the midbrain reticular formation and projects diffusely to layers I and VI of parietal cortex and to the basal telencephalic nuclei. The two projections are discussed in terms of specific and unspecific thalamocortical systems and as a basis for the concepts of essential and sustaining thalamocortical projections.
TL;DR: P neurones constitute the direct T-C projection system mediating the superficial T- C response to the parietal cortex, and are concluded to constitute the basic type of the so-called recruiting response.
Abstract: 1.
The cerebello-thalamo-cerebral projection system mediating the cerebellar-induced “superficial thalamo-cortical (T-C) response” (the basic type of the so-called recruiting response) to the anterior part of the middle suprasylvian gyrus was investigated electrophysiologically. Responses of thalamic neurones to stimulation of the cerebral cortex and the cerebellar nucleus (medial, interpositus and lateral) were recorded by microelectrodes.
2.
In the anterior portions of the ventral thalamic nuclear complex, presumably in and/or around the ventral anterior (VA) nucleus, there were found neurones responding antidromically to stimulation of the suprasylvian cortex and orthodromically to that of the interpositus and the lateral nucleus of the cerebellum. They were called P neurones. The neurones responding antidromically to stimulation of the anterior sigmoid cortex and orthodromically to that of the cerebellar nuclei located mostly caudo ventrolateral to the place of P neurones, presumably in and/or around the ventral lateral (VL) nucleus. These were called F neurones.
3.
The cerebellar excitation of P neurones was estimated on its latency to be monosynaptic and was usually followed by an inhibition lasting for more than 100 msec. Large unitary EPSPs were sometimes noted in P neurones on cerebellar stimulation as well as spontaneously. It was concluded that P neurones constitute the direct T-C projection system mediating the superficial T-C response (e. g., recruiting response) to the parietal cortex.
TL;DR: David Ferrier claimed in 1886 that monkeys subjected to large occipital lobectomies were unaffected by this drastic interruption of such a massive afferent channel, but there may have been an uninteresting explanation of these early results, because not all of the fibres from the lateral geniculate nucleus project to the lateral surface of the brain.
Abstract: 1. Introduction Of the three million or so nerve fibres that stream into the primate brain, about two million originate in the eyes. Of these fibres, about one-and-a-half million are in the geniculo-striate system, so named because it connects the eyes with a region of the thalamus known as the dorsal lateral geniculate nucleus and that nucleus with the striate cortex (also known as area 17 or area OC, figure 1) in the occipital lobes. About half, therefore, of all the inputs to the brain are fibres of retinal origin having relatively direct and concentrated access to the cerebral cortex. One may be allowed some surprise, therefore, to find that David Ferrier claimed in 1886 that monkeys subjected to large occipital lobectomies (figures 2, 3) were unaffected by this drastic interruption of such a massive afferent channel. He said 'I removed the greater portion of both occipital lobes at the same time without causing the slightest appreciable impairment of vision. One of these animals within 2 h of the operation was able to run about freely, avoiding obstacles, to pick up such a minute object as a raisin without the slightest hesitation or want of precision, and to act in accordance with its visual experience in a perfectly normal manner’ (Ferrier 1886, p. 273). Ferrier went on to say that ‘Horseley and Schafer inform me that their results of removal of the occipital lobes entirely harmonize with mine as to the completely negative effect of this operation’ (p. 276), which is a curious claim because two years later Schafer was locked in a most bitter dispute with Ferrier over just this point, and their argument is merely the most extreme example of the lack of agreement about the functions of the visual cortex in animals that has persisted over the years. We now know, with the benefit of hindsight, that there may have been an uninteresting explanation of these early results of Ferrier’s, because not all of the fibres from the lateral geniculate nucleus project to the lateral surface of the brain. Some of the striate cortex ─ that part which responds to stimulation of the most peripheral parts of the retinae ─ is buried in the calcarine fissure on the medial aspect of the brain, and the most anterior portion of this may be spared even after a complete occipital lobectomy (figure 1). Were Ferrier’s animals using an intact part of their visual space?
TL;DR: The inferior pulvinar nucleus of the macaque thalamus receives a visuotopically organised projection from the striate cortex, which represents the centre of gaze within the rostral regi.
Abstract: The inferior pulvinar nucleus of the macaque thalamus receives a visuotopically organised projection from the striate cortex. The centre of gaze is represented supero-laterally within the rostral regi
TL;DR: The various afferent pathways terminating in the thalamus of the marsupial phalanger have been investigated with the Nauta techniques, with a view to determining the extent of overlap and convergence of these pathways.
Abstract: The various afferent pathways terminating in the thalamus of the marsupial phalanger have been investigated with the Nauta techniques, with a view to determining the extent of overlap and convergence of these pathways. If this had proved to be extensive, it would have lent support to the views of some authors that, in primitive and generalized mammals, the relay nuclei are in the process of differentiating out of a single archetypical, multi-modal nucleus.
However, the amount of overlap between the various afferent pathways in this animal is no greater than in the cat and monkey; in the case of the ventral nuclear complex, despite the presence of a common sensory and motor cortical representation, the overlap between the somatic sensory and cerebellar pathways is probaly less than in the higher mammals. The question, therefore, arises as to whether differentiation of certain thalamic nuclei may precede that of the cortical area with which they are connected.
The results furnish evidence for the homologies of the posterior group of thalamic nuclei in other mammals, but the limited amount of overlap of afferent pathways occurring in the posterior group is not necessarily indicative of its being the common precursor of all the sensory relay nuclei.
TL;DR: Intracellular recordings from neurons in the dorsolateral segment of thalamic reticular nucleus have permitted interpretation of input-output functions of these elements during low-frequency stimulation of internal capsule, head of caudate nucleus, midline thalamus and substantia nigra, revealing the basis of intrathalamic gaiting of cerebellofugal impulses and synchronization of rhythmic activities in the reciprocal thalamocortical circuit.
TL;DR: In five patients with intractable generalized seizures and nonfocal electroencephalograms, direct brain recordings were made at rest, during spontaneously occurring seizure, and during pentylenetetrazol induced grand mal convulsion, indicating an important role for prefrontal cortex in the genesis of both idiopathic and acquired grand mal Convulsion.
Abstract: In five patients with intractable generalized seizures and nonfocal electroencephalograms, direct brain recordings (from prefrontal and parietal cortices, mesial temporal lobe, and mesial thalamus) were made at rest, during spontaneously occurring seizure, and during pentylenetetrazol induced grand mal convulsion. There was a limited correlation between EEG and records made directly from the brain; generalized atypical spike and wave activity which characterized the interictal EEG emanated from frontal lobes. Mesial thalamus did not show the atypical spike and wave activity seen in pre-frontal cortex; nor could such focal cortical discharge or convulsion be produced by stimulation of mesial thalamus. Both spontaneous and pentylenetetrazol induced grand mal convulsion originated in prefrontal cortex, the thalamus became involved secondarily. The findings together with those extant in current literature indicate an important role for prefrontal cortex in the genesis of both idiopathic and acquired grand mal convulsion.
TL;DR: Cortico-fugal facilitation appeared as reduced latency and increased probability of unit discharge in Anaesthetized cats, and the effect was frequency dependent, 10–20/sec being optimal.
Abstract: Recordings were made from units of the ventro-basal complex of the thalamus. Anaesthetized cats were stimulated by shocks to peripheral nerves and to somatosensory cortical points. Cortico-fugal facilitation appeared as reduced latency and increased probability of unit discharge. The effect was frequency dependent, 10–20/sec being optimal. It started about 1 msec after the cortical stimulus and lasted for 6–25 msec, dependent on the tetanus duration. Similar results are reported for the control of the medial geniculate body by auditory cortex.
TL;DR: 3 neonates with neuronal loss or encrustation and glial reaction in the reticular formation of the brainstem, inferior colliculus, thalamus, hypothalamus, and hippocampus are described.
Abstract: In 1959 Ranck and Windle reported that a single episode of acute asphyxia neona to rum produced experimentally in fetal monkeys had resulted in a consistent pat tern of brainstem and thalamic damage.’ Similar lesions in h u m a n beings have been reported infrequently. The present report describes 3 neonates with neuronal loss or encrustation and glial reaction in the reticular formation of the brainstem, inferior colliculus, thalamus, hypothalamus, and hippocampus. In 2 of these patients t he lesion was well established a t birth. In none was there clear evidence of asphyxia. However, late in pregnancy, the mothe r of 1 patient had taken an overdose of salicylates, which m a y have been responsible in some way fo r t he brain damage in the child.
TL;DR: The cyto‐ and myeloarchitectonic organization of the ventral nucleus of the lateral geniculate body (LGV) were investigated by means of several histological series sectioned in different planes to establish the shape of the nucleus and its anatomical relationships with the optic tract, the dorsal nucleus and the zona incerta.
Abstract: The cyto- and myeloarchitectonic organization of the ventral nucleus of the lateral geniculate body (LGV) were investigated by means of several histological series sectioned in different planes. Twenty-one hemispheres of normal adult cats were used. The shape of the nucleus and its anatomical relationships with the optic tract, the dorsal nucleus of the lateral geniculate body (LGD) and the zona incerta were established. The LGV is club-shaped with a broad main part and a slender stalk, which is twisted around the rostrolateral aspect of the optic tract. Caudolaterally the LGV is covered by the optic tract and dorsomedially it is apposed to the LGD. Rostromedially it merges with the thalamic reticular nucleus and ventromedially its stalk is continuous with the transition zone between the reticular nucleus and the zona incerta. Cell sizes were also measured. Five subdivisions of the nucleus were identified and their spatial interrelationships were determined: LGVa, LGVd and LGVe being composed of small cells exclusively, LGVb and LGVc containing both small- and medium-sized nerve cells. LGVa and LGVb are situated at the rostral part of the nucleus both fusing rostrally with the reticular nucleus of thalamus. LGVd occupies the caudal end of the nucleus. LGVe is situated along the contact zone with the optic tract and is combined with LGVc. LGVb is located between LGVa, LGVc and LGVd.
TL;DR: There are two distinct types of thalamocortical projections to parietal cortex in the opossum and the hedgehog that arise from the posterior portion of the ventral nuclear group of the do.
Abstract: There are two distinct types of thalamocortical projections to parietal cortex in the opossum and the hedgehog. Both projections arise from the posterior portion of the ventral nuclear group of the do
TL;DR: It is suggested that the caudally directed axonal path from nucleus reticularis thalami, in conjunction with the midline system, tune and shape those rhythmic slow wave processes which characterize thalamo-cortical operations.
Abstract: A number of variants of the Golgi method have been used to examine neuropil patterns and input-output arrangements of the nonspecific (intralaminar) thalamic complex in adult cats. In comparison with previously used newborn material, it is clear that maturation brings with it considerable change in dendritic and axonal circuitry in both specific and nonspecific systems. The latter provides an extensive second projection system to cerebral cortex in parallel with specific sensory channels. In addition, its connections enable it to exert powerful modulatory forces on the entire dorsal thalamus. It is suggested that the caudally directed axonal path from nucleus reticularis thalami, in conjunction with the midline system, tune and shape those rhythmic slow wave processes which characterize thalamo-cortical operations.
TL;DR: It is suggested that the nonspecific thalamus, amygdala and hippocampus are all critical for processing aversive information into a long-term memory store.