Showing papers on "Somatosensory system published in 1981"
TL;DR: It is proposed that pronouced NE-LC discharge may enhance activity within target cell systems primarily concerned with processing salient external stimuli and suppress cental nervous system activity related more to tonic, vegetative functions, which may bias global behavioral orientation between stimuli in the external versus internal environments.
Abstract: The effect of sensory stimulation on discharge in norepinephrine- containing locus coeruleus (NE-LC) neurons was studied in unanesthetized behaving rats. Single unit and multiple unit extracellular recordings demonstrated consistent patterns of response. (1) Short latency (15-to 50-msec), transient, biphasic changes in discharge were elicited predictably by non-noxious auditory, visual, and somatosensory stimuli; individual recordings typically exhibited polysensory responsiveness. (2) Sensory-evoked field potentials (FPs) were synchronized with unit responses simultaneously recorded from the same electrodes. (3) The magnitudes of sensory-evoked response varied as a function of vigilance, so that the largest responses occurred for stimuli which awakened animals and the least responsiveness was exhibited during uninterrupted sleep. (4) Sensory responsiveness decreased during grooming and sweet water consumption, similar to the results for sleep. (5) Characteristic response properties were topographically homogeneous throughout the NE-LC. (6) Discharge was synchronized markedly among neurons in multiple unit populations during phasic robust responses. These results are interpreted in light of the preceding report (Aston-Jones, G., and F.E. Bloom (1981) J. Neurosci. 1: 876–886) and studies of the postsynaptic effects of NE to indicate that the NE-LC system may function more in phasic processes than in modulation of the tonic arousal level. We propose that pronouced NE-LC discharge may enhance activity within target cell systems primarily concerned with processing salient external stimuli and suppress cental nervous system activity related more to tonic, vegetative functions. Thus, the NE-LC system may bias global behavioral orientation between stimuli in the external versus internal environments.
996 citations
TL;DR: It is argued that neurons with a receptive field consisting of several responding areas, some in one sensory modality and some in another, have a praxic function and that they are involved in organizing sequences of movements.
753 citations
TL;DR: The data are interpreted as evidence in favor of the existence of an area in the agranular cortex that organizes the mouth and the hand to mouth movements.
530 citations
TL;DR: The changes associated with normal aging have been confirmed and extended and a new widespread component N18 was identified and shown to be generated below the cortex.
388 citations
TL;DR: Testing with brainstem auditory and short-latency somatosensory evoked resonses suggests that the SER has greater clinical utility in the brain-death setting, because it is important to have a wave present that establishes that the input signal has reached the central nervous system.
Abstract: Thirty-five patients who met all clinical criteria for brain death and 53 patients who did not were tested with brainstem auditory (BAER) and short-latency somatosensory (SER) evoked responses. Of the brain-dead patients, 77% had no waves present in the BAER, including wave I, whereas 69% had medullary components present in the SER. These data suggest that the SER has greater clinical utility in the brain-death setting, because it is important to have a wave present that established that the input signal has reached the central nervous system. No brain-dead patients had subsequent waves in either test. These results are correlated with neuropathologic findings and contrasted with data obtained in the comatose but not brain-dead patients.
248 citations
TL;DR: The finding of a differential distribution of cutaneous inputs within MI is of significance to hypotheses concerning the role of somatosensory input to the MI cortex, and to studies that attempt to characterize somatoensory inputs to MI by the proportion of neurons responsive to cutaneous and noncutaneous stimulation.
Abstract: 1. Neuronal responses to cutaneous and noncutaneous stimulation were examined in the hindlimb representation of the precentral motor cortex (MI) and the first somatosensory cortex (SI) of unanesthetized monkeys. 2. MI can be divided into two distinct parts of the basis of its afferent input. The rostral part receives predominantly noncutaneous inputs, while the cutaneous input is primarily confined to the caudal part of MI. Thus, a differential distribution of submodality groups exists in the MI cortex. Caudal to MI, area 3a responds mainly to stimulation of noncutaneous receptors, in marked contrast to the caudal part of MI or area 3b. 3. The finding of a differential distribution of cutaneous inputs within MI is of significance a) to hypotheses concerning the role of somatosensory input to the MI cortex, b) to studies that attempt to characterize somatosensory inputs to MI by the proportion of neurons responsive to cutaneous and noncutaneous stimulation, and c) in that they confirm and extend similar findings recently reported for the forelimb representation of an anesthetized New World monkey (43).
179 citations
TL;DR: The spatial and temporal properties of the early portion of the somatosensory evoked potential (SEP) were assessed in normal human subjects and in monkeys, cats, and rats, suggesting direct correspondences between human and animal components.
165 citations
TL;DR: The distribution of two functionally distinct cell types, presumably related to slowly and rapidly adapting mechanoreceptors in the skin, was explored within the representation of the glabrous hand in area 3b of the somatosensory cortex of monkeys.
Abstract: The distribution of two functionally distinct cell types, presumably related to slowly and rapidly adapting mechanoreceptors in the skin, was explored within the representation of the glabrous hand in area 3b of the somatosensory cortex of monkeys. The two cell classes lie in relatively segregated alternating anteroposterior bands within the middle layers of the cortex.
131 citations
TL;DR: The finding that movement rather than arousal or attentiveness caused the most potent modulation of the sensory responsiveness and firing rates of SI cortical cells suggests that this cortical area may be closely integrated with central nervous system motor functions.
121 citations
TL;DR: Using threshold stimulating currents in SI, the projections from small populations of neural elements were found to be highly restricted, terminating within the confines of only those tactile cerebellar hemispheric locations having the same receptive fields (RFs).
Abstract: We defined spatial patterns of organization of projections from somatosensory cerebral cortex (SI) to the somatosensory cerebellar cortex of anesthetized albino rats using microelectrode (stimulation
121 citations
TL;DR: Single neurons were recorded from the "mouth area" of the postarcuate cortex in macaque monkeys to subdivide them into three classes according to their responses to somatosensory stimuli and their activity during the animal's movements.
TL;DR: The hypothesis that changes in somatosensory evoked potentials may reflect build-up of inhibition at synapses of the dorsal column/medial lemniscal pathway, due to input from cutaneous touch receptors and proprioceptors is supported.
TL;DR: The results indicate that the activation of peripheral receptors during both active and passive finger movement would induce a gating effect at both cortical and subcortical (thalamic) level, which might modulate selectively the different sensory inputs to the cortex.
Abstract: The effects of active and passive finger movements on somatosensory potentials evoked by stimulation of the median nerve at the wrist or of finger I were investigated in 15 healthy volunteers. As compared to the resting condition, both active and passive movements of the stimulated hand fingers induced a marked reduction in the amplitude of the primary cerebral response (N20-P25 complex) as well as of the N17 SEP component, which is supposed to reflect the activity of the thalamo-cortical radiation. The following cerebral SEP components, within 100 ms after the stimulus, were also depressed during motor activity. Neither N11 nor N13 components of the cervical response, reflecting the activation of dorsal columns and dorsal column nuclei respectively, were modified. The SEP changes induced by active or passive movements were absent after ischaemic block of large group I afferent fibers from the hand, thus suggesting the relevance of the feedback generated by such peripheral afferents during movement. The results indicate that the activation of peripheral receptors (probably muscle spindle endings) during both active and passive finger movement would induce a gating effect at both cortical and subcortical (thalamic) level, which might modulate selectively the different sensory inputs to the cortex.
TL;DR: Although halothane anesthesia slightly depressed the short latency response component of single units in the primary somatosensory cortex of rats, its main effect was to depress the longer latency excitatory components (E1b and E2) which exhibited relatively "nonspecific" properties.
01 Nov 1981
TL;DR: Descending monoamine pathways have been shown to modulate the processing of nociceptive information and the role of this system appears to be in modulating the properties of sensory processing at the spinal cord level.
Abstract: Descending monoamine pathways have been shown to modulate the processing of nociceptive information. Several lines of evidence support this hypothesis: 1) stimulation of brain-stem sites by intracerebral electrodes or the local application of opiates inhibits spinal reflex activity, this effect being antagonized by intrathecal monoamine antagonists; 2) the iontophoretic administration of monoamines in the spinal cord will antagonize the discharge of dorsal horn nociceptors; and 3) the intrathecal administration of monoamines will elevate the pain threshold in the unanesthetized animal. One natural mode of activating this intrinsic circuit appears to be through the activation of small-diameter afferents. Recent evidence has shown that such somatic stimulation causes the release of 5-hydroxytryptamine and norepinephrine. The role of this system appears to be in modulating the properties of sensory processing at the spinal cord level.
TL;DR: Compared with normal animals, the receptive fields of cortical neurons in amputated animals were larger, often included both glabrous and hairy skin, sometimes involved discontinuous skin regions, and were much more variable in peripheral location as a function of recording distance across the cortex and of depth within the cortex.
TL;DR: Horseradish peroxidase (HRP) histochemistry was used to visualize cells afferent to the bullfrog torus semicircularis, and afferents from spinal cord cells proved difficult to visualize.
Abstract: Horseradish peroxidase (HRP) histochemistry was used to visual- ize cells afferent to the bullfrog torus semicircularis. These afferent cells are located in several sensory and nonsensory nuclei. The sensory structures which project to the torus are mainly auditory nuclei, with the major input coming from the ipsilateral superior olive. A very small contralateral projection is also present. In addition, afferents arise from the contralateral, and to a lesser extent ipsilateral, dorsal acoustic nucleus and nucleus caudalis, both primary eighth nerve nuclei. A vestibular input is also apparent in that HRP-positive cells were seen in the magnocellular vestibular nucleus and among elongated bipolar cells at the ventral border of the eighth nerve nuclei. In addition, the torus receives somatosensory input from the contralateral perisolitary band. Afferents from spinal cord cells proved difficult to visualize. Nonsensory areas throughout the brain innervate the torus as well. In the medulla, HRP-positive cells were present bilaterally in both medial and lateral reticular areas. The tegmentum contributes a major input from the superficial isthmal reticular nucleus and a minor input from the tegmental fields. Commissural toral projections are also present. Descending forebrain input arises from the pretectal gray bilaterally, the ventral half of the ipsilateral lateral pretectal nucleus, and, possibly, from the ipsilateral posterior thalamic nucleus. HRP-positive cells were also occasionally seen in the posterior tuberculum, ventral hypothalamus, and caudal suprachiasmatic preoptic area. Finally, a telencephalic projection from the ipsilateral anterior entopeduncular nucleus is present.
TL;DR: Nearly 40% of diabetics have subclinical electro-physiologic dysfunction of the posterior columns of the spinal cord, which may contribute to the lower-extremity sensory symptoms that are so prevalent in this disorder.
Abstract: The velocity bf impulse conduction was compared in peripheral nerve, spinal cord, and supraspinal segment of the somatosensory pathway in 15 diabetic subjects (mean age, 34.3 ± 12.4 years) with little or no evidence of polyneuropathy, and in 15 age-matched normal controls. Motor and sensory conduction velocities (CVs) were slower in the diabetic subjects, and the latencies of F waves and somatosensory evoked potentials (SEPs) from arm and leg were longer ( p p p p
TL;DR: The authors identified the sites of origin of the somatosensory evoked potentials to median nerve stimulation by recording directly from the cervical cord in the course of intraoperative monitoring, suggesting that this potential is generated at the cervicomedullary junction.
Abstract: we identified the sites of origin of the somatosensory evoked potentials to median nerve stimulation by recording directly from the cervical cord in the course of intraoperative monitoring The N9 potential occurred before any potentials recorded from the cord or dorsal roots Potentials with latencies corresponding to N11 were recorded at the median nerve root entry zone of the lower cervical cord High-amplitude potentials were recorded at the level of the foramen magnum, with latencies approximating or following P13, suggesting that this potential is generated at the cervicomedullary junction
TL;DR: Abnormalities of visual, brainstem auditory, and somatosensory evoked responses were demonstrated in two of seven individuals with vitamin B12 deficiency and correlated directly with the degree of neurological dysfunction.
Abstract: Abnormalities of visual, brainstem auditory, and somatosensory evoked responses were demonstrated in two of seven individuals with vitamin B12 deficiency. The evoked response delays correlated directly with the degree of neurological dysfunction. Abnormalities were present in sensory systems without clinical evidence of involvement and were similar to those found in individuals with multiple sclerosis.
TL;DR: The same type of organization, with identical thresholds, existed in the so-called “Motor” and “Somatosensory” cortical zones and it is thought that the movements were due to a spread of the stimulating current to the pyramidal tract cell layer.
Abstract: Experiments using the same glass microelectrode (6–8 MΩ) for recording and stimulating were performed on 12 rats in which 379 cortical cells were studied in 65 penetrations through the motor and somatosensory cortical zones. To avoid anaesthetic effects the rats were chronically implanted with a head system derived from the one developed by Noda et al. (1971). These animals well accepted head fixation and the peripheral receptive fields could thus be easily investigated. In a preliminary experiment the number of pyramidal cells activated by a given stimulus intensity was evaluated. The lowest threshold intensities were always observed in the Vth pyramidal layer, as well as correspondence between cell input and output. The same type of organization, with identical thresholds, existed in the so-called “Motor” and “Somatosensory” cortical zones. Movements could be obtained when stimulating near non-PT cells (600–700 μm below the cortical surface). However, thresholds were higher at this level and it is thought that the movements were due to a spread of the stimulating current to the pyramidal tract cell layer.
TL;DR: Neural mechanisms used to encode kinesthetic information in somatosensory cortex of awake monkeys are studied, finding velocity of movement is the most important determinant of firing rates of rapidly- Adapting and slowly-adapting kinesthetic neurons, and joint angle predominates the responses of postural neurons.
TL;DR: Patients with unilateral brachial plexus traction lesions were investigated by recording sensory nerve action potentials from the lower arm and somatosensory evoked potentials in response to electrical stimulation of peripheral nerves, and combination of SEP and SNAP findings suggested a location for the lesion.
Abstract: Forty-two patients with unilateral brachial plexus traction lesions were investigated by recording sensory nerve action potentials (SNAPs) from the lower arm and somatosensory evoked potentials (SEPs) from the clavicle, the cervical spine and the scalp overlying the contralateral somatosensory cortex, in response to electrical stimulation of peripheral nerves. The median and radial nerves were assumed to derive principally from the C6 and C7 roots, and the ulnar nerve from the C8 and T1 roots. Combination of SEP and SNAP findings suggested a location for the lesion (preganglionic, postganglionic or combining pre-and postganglionic elements) which was found to be accurate in 10 out of 16 operated cases, and substantially accurate in another 3. There was a poor correlation, however, between the presence of absence of SNAPs in the musculocutaneous nerve and the location of the lesion to the C5 root.
01 Jan 1981
TL;DR: The intention of this narrative is to briefly survey features of the organization of the V. nerve, ganglion, root and its central brain stem nuclei with some emphasis on those characteristics that should be taken into account by the enlightened clinician.
Abstract: The trigeminal nerve is the largest sensory nerve of most mammals. Its central projections dominate the somatosensory system, and trigeminal reflexes are the first to appear in fetal development. A comparison of the trigeminal nerve with its spinal. counterparts reveals a remarkable number of structural specializations which presumably reflect its distinctive functional role. It is the intention of this narrative to briefly survey features of the organization of the V. nerve, ganglion, root and its central brain stem nuclei with some emphasis on those characteristics that should be taken into account by the enlightened clinician.
TL;DR: Somatosensory evoked potentials recorded during moderate anaesthesia showed delays of nearly 1 msec in anterior component III from the thalamus and sensory radiation, and the subsequent cortical potentials.
01 Jan 1981
TL;DR: These studies led to several important conclusions: the region of postcentral cortex activated by tactile somatic stimuli includes the separate architectonic fields 3 (3a and 3b), 1 and 2 of Brodmann; the cortex is activated almost exclusively from the contralateral half of the body.
Abstract: Many of our present day concepts of the organization of somatosensory cortex stem from the landmark study of Woolsey, Marshall and Bard, first published in 1937 (7) and then more completely in 1942 (21). These investigators documented important features of the overall organization of the postcentral parietal cortex in Macaca mulatta by recording evoked potentials from the surface of the brain. The basic procedure was to determine the portion of the body surface (the receptive field), where movements of hairs or punctate stimulations of glabrous surfaces with a cat’s vibrissa were capable of evoking responses at a given recording site and to repeat the procedure for a grid of closely spaced recording sites. By removing parts of the brain, they were even able to explore cortical surfaces buried in the central sulcus and on the medial wall of the cerebral hemisphere. These studies led to several important conclusions: (a) the region of postcentral cortex activated by tactile somatic stimuli includes the separate architectonic fields 3 (3a and 3b), 1 and 2 of Brodmann; (b) the cortex is activated almost exclusively from the contralateral half of the body; (c) there is an orderly representation of body parts, with a medial to lateral sequence across cortex from tail to tongue along the body; (d) the cortical organization does not exactly reflect the body surface, so that there are displacements in the cortical map; one clear example given was the separation in cortex of the representation of the face from the caudal head; and (e) the skin surfaces with the greatest tactile acuity have the largest cortical projection areas.
TL;DR: The distribution of S1 and S2 neurons projecting to the contralateral S2 was studied with horseradish peroxidase in normal adult cats and in cats aged between 129 and 248 days in which the injected S2 area had been deprived of some of its input by an earlier lesion.
Abstract: The distribution of S1 (first somatosensory area) and S2 (second somatosensory area) neurons projecting to the contralateral S2 was studied with horseradish peroxidase in normal adult cats and in cats aged between 129 and 248 days in which the injected S2 area had been deprived of some of its input by an earlier lesion (on postnatal days 3 to 30; day of birth = day 1) of ipsilateral S1, alone or combined with a lesion of contralateral S2. In animals with S1 lesions, as in the normal controls, labeled neurons were selectively distributed to the regions of the trunk representation and to parts of the forelimb and hindlimb representations; however, the normally acallosal region in the forepaw representation contained scattered labeled neurons in three of the four animals whose S1 had been lesioned during the first postnatal week. In these animals, the distribution of labeled neurons in the contralateral S2 was apparently normal. Furthermore, the additional lesion of this area during the first postnatal week (one animal) did not increase the degree of filling-in of the normally acallosal parts of S1. The partial filling-in of the acallosal parts of S1 is probably due to the preservation to adulthood of some of the callosal neurons which are present in these regions during the early postnatal life. Possibly, these neurons did not disappear (or lose their callosal axons) because the neonatal lesion (i) allowed their successful competition for terminal space in contralateral S2 or (ii) induced a reorganization of the peripheral input to this area.