Changes in the functional characteristics of Clare-Bishop area cells after partial unilateral isolation of the neocortex in cats

Evoked unit activity was investigated bilaterally in neurons of the Clare-Bishop area in cat brain after unilateral severing of the posterior limb of the internal capsule. Cell responses to photic, acoustic, and somatosensory stimuli, also to electrical stimulation of the association areas of the neocortex were investigated. The most rudimentary type of response to a diffuse light flash, electrical stimulation of the forepaw skin, and acoustic stimulation was restored in a proportion of test cells in the operated hemisphere within one week of operating. Sensitivity to visual stimuli increased considerably in cells of the Clare-Bishop area of the intact hemisphere during the first week after the operation. All test cells responded to presentation of light flashes; 80% had receptive fields located to electrical stimulation of the forepaw skin. Seven days after the operation the number of cells responding to photic stimulation fell to 35% and only 17% of cells responded to somatosensory stimuli. This article discusses features of the neuronal compensatory reorganization of the Clare-Bishop area and its role in the recovery of visual function.Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 180–187, March–April, 1986.     

Involvement of visual specific and association cortex input in the shaping of neostriatal neuron response to visual stimulation in unanesthetized cats

During chronic experiments on unanesthetized cats neuronal response in the caudate nucleus to the presentation of local photic stimuli and electrical stimulation of the specific (field 17) and the association (Clare-Bishop) areas were compared. Stimulation of the Clare-Bishop area proved more effective than stimulating field 17 for neurons of the caudate nucleus; a response was produced in 47% of test neurons in comparison with 8% of units only in the specific area. Lower average values were observed for latency of neuronal response to stimulation of the Clare-Bishop area. An insignificant number of caudate nucleus neurons were activated as a result of stimulation of both cortical areas. A comparison between the response of one set of neurons to electrical cortical and visual stimulation showed that cells responding to visual stimulation were more highly activated by stimulating the Clare-Bishop area than by stimulation of field 17. This type of neuron predominated in the caudate nucleus. A discussion follows of the possible involvement of the Clare-Bishop area in shaping neuronal response to visual stimulation.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 17, No. 5, pp. 619–627, September–October, 1985.     

Unit responses of the clare-bishop cortical association area in the cat to photic stimulation

Electrical activity of single unit in the Clare-Bishop visual association area of the cortex was studied in acute experiments on cats immobilized with Flaxedil and after pretrigeminal sections. The method of extracellular recording of action potentials of single units was used. The experimental results showed that 95.5% of cells responding to visual stimulation responded to movement of a spot of light in the receptive field of the neurons, and 55% of the cells responded selectively to the direction of movement. Some neurons responded to movement of a stimulus only when it entered and left the receptive field. About 85.3% of cells responded to a flashing spot of light, and also to a general change in the intensity of illumination of the receptive field. The receptive field of neurons of the Clare-Bishop area in most cases were in the form of stripes with their long axis horizontal. The results point to the important role of this cortical association area in the central analysis of visual information.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSSR, Erevan. Translated from Neirofiziologiya, Vol. 10, No. 1, pp. 22–29, January–February, 1978.     

Responses of neurons of reticular and ventral anterior nuclei of the cat thalamus to afferent stimuli of different modalities

Responses of 146 spontaneously active neurons of the reticular nucleus (R) and of 98 neurons of the ventral anterior (VA) nucleus of the thalamus to electrical stimulation of the skin of the footpads, to flashes, and to clicks were studied in experiments on cats immobilized with D-tubocurarine or myorelaxin. Stimulation of the contralateral forelimb was the most effective: 24.9% of R neurons and 31.3% of VA neurons responded to this stimulation. A response to clicks was observed in only 4.4% of R neurons and 2.4% of VA neurons. Nearly all responding neurons did so by phasic (one spike or a group of spikes) or tonic excitation. Depression of spontaneous activity was observed only in response to electrical stimulation of the skin. Depending on the site of stimulation, it was observed in 2.6–4.3% of R neurons and 1.7–2.1% of VA neurons tested. The latent period of the phasic responses of most neurons was 6–64 msec to electrical stimulation of the contralateral forelimb, 11–43 msec in response to stimulation of the hindlimb on the same side, 10–60 msec to photic and 8–60 msec to acoustic stimulation. Depending on the character of stimulation, 75.1–95.6% of R neurons and 68.7–97.6% of VA cells did not respond at all to the stimuli used. Of the total number of cells tested against the whole range of stimuli, 25% of R neurons and 47% of VA neurons responded to stimulation of different limbs, whereas 16% of R neurons and 22% of VA cells responded to stimuli of different sensory modalities. The functional role of the convergence revealed in these experiments is to inhibit (or, less frequently, to facilitate) the response of a neuron to a testing stimulus during the 40–70 msec after conditioning stimulation.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 7, No. 6, pp. 563–571, November–December, 1975.     

Electrophysiological investigation of effect of pulvinar stimulation of caudate nucleus neurons that react to visual stimulation

Responses of caudate neurons to electrical stimulation of the afferent input from thepulvinar thalamic nucleus and to visual stimuli of various orientations were studied extracellularly in awake chronic cats. Activation responses dominated among reactions of these neurons. The response latencies have ranged from 4 to 85 msec for units with primary activation and from 20 to 150 msec for inhibited ones. The values are indicative of both rapidly and slowly conducting afferent pathways. A possibility of monosynaptic transmission in thepulvinarcaudate projections is also revealed.Pulvinar stimulation is found to be efficient for a significant (more than 50 percent) number of caudate neurons responding to visual stimuli, including orientation-selective cells. The mode of influences from other structures of the visual system (optic tract, area 17, the Clare-Bishop area) on caudate neurons responding topulvinar stimulation is described. The data are discussed with respect to the possible role of cortical and subcortical projections of the visual system in the creation of sensory specific responses of the caudate nucleus.A. A. Bogomolets Physiology Institute, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 520–529, September–October, 1991.     

Convergence and interaction of reticulofugal and peripheral afferent impulses on caudate neurons in the cat

Extracellular investigations on the activity of 269 caudate neurons during electrical stimulation of the midbrain reticular formation were carried out during chronic experiments on cats. Stimuli of different sensory modalities were used: auditory, mechanical, and visual. A response was observed to both reticular and peripheral stimulation in single neurons. The former produced an orthodromic response in 53% of caudate neurons, notable for its high probability of occurrence. A total of 23% of caudal neurons responded to this type of stimulation and application of stimuli of a single modality, while 14% responded polymodally. An excitatory response pattern prevailed during all types of stimulation. By applying twin stimuli to 100 caudate neurons, a capacity for interaction between reticular and acoustic inputs was discovered. Interaction was similarly observed in neurons which had reacted neither to separate application of both stimuli nor to either of the stimuli in isolation.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 1, pp. 101–110, January–February, 1987.     

Receptive fields of neurons of cat suprasylvian gyrus studied by stimuli of different colors

Receptive fields of 83 neurons in the Clare-Bishop area and 75 neurons in cortical areas 17 and 18 were studied. Testing receptive fields of neurons in the Clare-Bishop area by stimuli of different colors revealed differences in their structure, in 95% of neurons, depending on stimulus color. The structure of the receptive fields of neurons in areas 17 and 18 remained unchanged under these conditions. It is suggested that the Clare-Bishop area participates in color vision in the cat.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 14, No. 6, pp. 644–650, November–December, 1982.     

Response of neostriatal neurons to direct electrical stimulation of the optic tract and photic stimulation in awake cats

During acute experiments on awake cats the response of 98 neurons belonging to the head and tail of the caudate nucleus to direct electrical stimulation of the optic tract and presentation of photic stimuli was investigated using extracellular recording techniques. Of the test neurons 34.6% responded to stimulation of the optic tract and 36.2% to optic stimulation. Long latency (over 40 msec for the optic tract and over 80 msec for visual stimulation) excitatory responses prevailed in both cases. A small number of cells responded to optic tract stimulation with short latencies of 5–14 msec. Both types of stimulation were presented during investigations of 58 units of which eight were found to respond to both stimuli. The latter varied in their reaction to different stimuli and their response pattern. Findings are discussed in relation to the possible pathways by which visual information reaches the cortical structure under study.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 4, pp. 476–485, July–August, 1986.     

Electrophysiological analysis of the functional organization of cortico-cerebellar connections

The effect of stimulation of cortical association (orbito-frontal, parietal) and projection (auditory, sensomotor) areas on the activity of Purkinje neurons of the cerebellar cortex was studied in adult cats anesthetized with pentobarbital, with or without chloralose. These responses were compared with those to peripheral stimuli. Definite similarity was found between the responses of Purkinje cells to different cortical (association and projection) stimuli as regards both the types of responses of the neurons and their ability to respond. No similarity was observed in the responses of Purkinje cells to peripheral (visual, auditory, electrodermal) stimulation. Whereas almost identical numbers of neurons (over 50%) were excited in response to the different forms of cortical stimulation, the ability of the neurons to respond to peripheral stimuli differed considerably: 44.6% of neurons responded to electrodermal stimulation, 34.2% to auditory, and 18.8% to visual.Medical Institute, Kemerovo. Translated from Neirofiziologiya, Vol. 8, No. 5, pp. 483–489, September–October, 1976.     

Organization of neurons responding to photic stimulation in the Clare-Bishop area in cats

Neuronal organization in the Clare-Bishop cortical association area was studied by consecutive vertical penetration of an electrode and analysis of unit responses to photic stimulation during each penetration. Activity of one or two neurons was recorded during 131 penetrations, and activity of over 3 neurons responding to photic stimulation (visually driven) during 55 penetrations. In 8 of the 55 penetrations all neurons discovered in each had identical characteristics; this type of organization corresponded most of all to the columnar organization of the cortical neurons. In 24 penetrations the neurons were arranged in groups: two or three neurons of one type intermingled with neurons of other types. In 18 penetrations considerable overlapping of the receptive fields of neurons in the same column was observed. A chaotic distribution of neurons with different characteristics was found in 5 penetrations. It is suggested that the organization of neurons in the Clare-Bishop area in columns as functional units of cortical structure is not the principal type of their organization.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 11, No. 4, pp. 297–302, July–August, 1979.     

Responses of parietal associative neurons to stimulation of primary sensory areas

Responses of 251 neurons in the anterior part of the middle suprasylvian gyrus to stimulation of primary sensory (auditory, visual, somatosensory) areas and also to acoustic, visual, and somatosensory stimuli were studied in acute experiments on cats anesthetized with chloralose (40 mg/kg) and pentobarbital (20 mg/kg). Three groups of neurons were distinguished by their responses to stimulation of the primary sensory areas: those responding by an increased firing rate (117) or by inhibition (35) and those not responding (99). Responses of 193 neurons to stimulation of the peripheral afferent systems were analyzed. Neurons of the parietal associative cortex responded more frequently to cortical stimulation than to peripheral. By the duration of the latent period of their response to cortical stimulation the neurons were divided into three groups: those with short (less than 20 msec), medium (20–30 msec), and long latent periods (over 30 msec). The first group was the largest.Kemerovo State Medical Institute. Translated from Neirofiziologiya, Vol. 4, No. 5, pp. 524–530, September–October, 1972.     

Two patterns of bulbar neuronal response to microstimulation of locomotor and inhibitory brain stem sites

Synaptic responses (postsynaptic potentials and action potentials) were evoked in mesencephalic decerebellated cats by stimulating pontine bulbar locomotor and inhibitory sites (LS and IS, respectively) with a current of not more than 20 µA in "medial" and "lateral" neurons of the medulla. Some neurons even produced a response to presentation of single (actually low — 2–5 Hz — frequency) stimuli. The remaining cells responded to stimulation at a steady rate of 30–60 Hz only. Both groups of medial neurons were more receptive to input from LS. Lateral neurons responding to even single stimuli reacted more commonly to input from LS and those responding to steady stimulation only to input from IS. Many neurons with background activity (whether lateral or medial) produced no stimulus-bound response, but rhythmic stimulation either intensified or inhibited such activity. This response occurs most commonly with LS stimulation. Partial redistribution of target neurons in step with increasing rate of presynaptic input may play a major part in control of motor activity.Institute for Research into Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 2, pp. 257–266, March–April, 1990.     

Multisensory convergence on neurons of the motor cortex in unanesthetized cats

Postsynaptic potentials (PSPs) of 83 neurons in the motor cortex of unanesthetized cats in response to electrodermal, photic, and acoustic stimulation were investigated by intra-and quasi-intracellular recording methods. Most cells responded to stimulation of at least one limb. About 60% of neurons of the posterior and over 75% of neurons of the anterior sigmoid gyrus responded to stimulation of two (or more) limbs. In 29 of 39 neurons of the anterior and 12 of 44 of the posterior sigmoid gyrus PSPs with a short (less than 50 msec) and stable latent period were evoked by flashes and clicks. On presentation of two somesthetic stimuli complete blocking (if the interval was less than 30–60 msec) or weakening (interval 30–200 msec) of responses to the second (testing) stimulus was observed. On presentation of paired photic (or acoustic) stimuli or paired stimuli of different modalities at various intervals from 0 to 100 msec, the testing response was often potentiated. The character of the responses and their interaction thus differed from those obtained under chloralose anesthesia [6, 7]. It is postulated that under the action of chloralose a system of neurons with strong excitatory feedback is formed in the motor cortex which may respond to stimuli of different modalities by something resembling the "all or nothing" principle.Brain Institute, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 6, pp. 563–573, November–December, 1971.     

Mechanisms of interaction between the parietal association and projection areas of the cat neocortex

Changes in evoked potentials in the first visual (VI), first somatic (SI), and parietal areas of the cortex during local cooling of each area were investigated under pentobarbital anesthesia. Two types of interaction were distinguished. Type I interaction was found in all areas in the early stages of local cooling and was reflected in a similar decrease in amplitude of evoked potentials in intact parts of the cortex. In the thalamic association nuclei — the pulvinar and posterolateral nucleus — somatic evoked potentials were unchanged but visual were transformed differently from those in the cortex. Type IIinteraction was found in the later stages of cooling and only between the association area and each of the projection areas. It was reflected in a greater change in amplitude of the evoked potentials and also in their configuration. In response to somatic stimulation in the early stage of type II interaction transformation of evoked potentials in the cortex took place sooner than in the nuclei; in the later stage it took place immediately after transformation of the "subcortical" evoked potentials. In response to photic stimulation transformations of cortical evoked potentials were always preceded by the corresponding transformations in the nuclei. It is suggested that type I interaction is formed by intercortical connections and type II by direct and subcortical relay connections. Differences in the role of the association area in interaction of types I and II when activated by stimuli of different modalities are discussed.Brain Institute, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 10, No. 6, pp. 573–581, November–December, 1978.     

Morphological and physiological study of afferent projections of the posterolateral thalamic nucleus in rats

It was shown by the method of retrograde axonal transport of horseradish peroxidase that the posterolateral thalamic nucleus (NPL) in rats receives considerable ascending projections from the superior colliculus (SC), the dorsal part of the lateral geniculate body (LGB), and the pretectal region (PT) and smaller projections from n. ventralis posterior (VP) and n. ventralis lateralis (VL) of the thalamus, the ventral part of LGB, the zona incerta, and anterior hypothalamus. The most marked descending projections run into NPL from area 18A of the cortex and the dentate fascia of the hippocampus, whereas inputs from cortical areas 18, 20, 7, 29c, 17, and 36 are less marked. In electrophysiological experiments with peripheral stimulation of visual, auditory, and somatosensory systems, polysensory convergence and interaction between signals from these systems were studied during isolated and simultaneous presentation of heterosensory stimuli. Of 229 neurons tested, 134 (58.5%) responded to at least one of the stimuli mentioned. Among monomodal neurons (53 of 134) there were some cells which responded to visual (77.4%) and somatic (22.6%) stimulation; neurons which responded only to acoustic stimulation were not found in the nucleus. As far as polymodal neurons (81 of 134) responding to two or three sensory stimuli are concerned, the most effective inputs of these units were visual and somatosensory. Interaction between stimuli acting on polymodal neurons was expressed as mutual inhibition or facilitation of responses; opposite effects could be observed on the various components of these responses.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 16, No. 2, pp. 168–176, March–April, 1984.     

Long-term modifications of unit activity in area 7 of the cat neocortex after unilateral division of the optic radiation

Changes in functional characteristics of cells in area 7 of the cat parietal cortex at different times after unilateral division of the optic radiation were studied in semichronic experiments. Neuronal responses were studied in the affected and intact hemispheres to adequate stimuli of different modalities and to direct electrical stimulation of the primary neocortical projection zones. In area 7 on the side of the operation neuronal sensitivity to stimuli of different sensory modalities were restored. In area 7 of the intact hemisphere the number of cells with local receptive fields gradually increased after the operation and the average size of the receptive fields also increased. It is concluded that mechanisms of plasticity of the partietal association cortex are based on the ability of cells of this zone to receive impulses, via the system of intracortical association fibers, from other sensory or nonspecific brain systems, and also their ability to reorganize their firing pattern depending on changing internal and external environmental conditions.Research Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 17, No. 1, pp. 50–57, January–February, 1985.     

Responses of cat pulvinar neurons to moving visual stimuli

Responses of 114 pulvinar neurons to moving visual stimuli were studied. Most (79) neurons possessed spontaneous activity (10–25 spikes/sec). Of 59 neurons tested, 31 responded to stimulation of both retinas and 28 to stimulation only of the contralateral retina. Of 114 neurons, 41 responded only to movement of black objects, while the rest responded to movement of both black and light objects. According to the character of their responses to movement the neurons were divided into two main groups. The first group consisted of neurons sensitive to the direction of motion and responding with a spike discharge to movement in one direction and by inhibition to movement in the opposite direction. The second group included neurons insensitive to the direction of motion and responding by an equal number of discharges to movements in two opposite directions. Besides these two main groups, other neurons responding to movement in two opposite directions by discharges with different temporal distribution and also neurons which changed the character of their response from nondirectional to directional depending on the size of the moving stimulus, were found.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 10, No. 4, pp. 348–354, July–August, 1978.     

Responses of rabbit visual cortical neurons to intracortical electrical stimulation

Responses of rabbit visual cortical neurons to single and repetitive intracortical electrical stimulation were investigated. The stimulating electrode was located 0.7–1.2 mm away from the recording electrode. Response thresholds to single stimulation were as a rule 150–180 µA, whereas to series of stimuli they were 30–60 µA. The latent period to the first spike averaged 5–15 msec but the probability of the initial discharge was very low, namely 3–6%. With an increase in current intensity the duration of the initial inhibitory pause was increased in half of the neurons responding to it, whereas in the rest it was unchanged. After presentation of series of stimuli spontaneous activity was enhanced for a short time (4–6 sec). In about half of the cells the same kinds of discharge dynamics were observed in response to repetitive stimulation (frequency 0.25 Hz) as in responses to light, but more neurons with sensitization of discharge and fewer "habituating" neurons took part in responses to electrical stimulation. It is postulated that stimulation of a given point of the visual cortex evokes excitation of a local neuron hypercolumn and inhibition of neighboring cell columns.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 15, No. 4, pp. 412–419, July–August, 1983.     

Unit responses of the cat suprasylvian gyrus to flashes of different wavelengths

Unit responses in the suprasylvian gyrus of the cat to flashes of different wavelengths were studied. Especially in the Clare-Bishop region, about 80% of suprasylvian neurons were found to be color-specific. Four classes of neurons responding differently to different regions of the spectrum were distinguished. The possible principle of coding of information on stimulus color by neurons of the suprasylvian areas is discussed.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 11, No. 1, pp. 11–17, January–February, 1979.     

Conduction of excitation in the cat visual system

Unit responses in area 17 of the visual cortex to stimulation of the lateral geniculate body and optic tract were studied in experiments on unanesthetized cats immobilized with D-tubocurarine. Of the neurons tested, 53.6% responded to stimulation of the lateral geniculate body. In 92% of these cells the responses were orthodromic with latent periods of between 2 and 12.5 msec. Most cells responded with latent periods of 2.0–2.5, 3.0–3.5, and 4.0–4.5 msec, corresponding to latent periods of the components of the electropositive wave of the primary response. Antidromic responses to stimulation of the lateral geniculate body were given by 8% of neurons. The difference between the latent periods of responses of the same visual cortical neurons to stimulation of the optic tract and lateral geniculate body was 0.1–1.8 msec, but for most neurons (55.8%) it was 0.5–1 msec. The histograms of response latencies of visual cortical neurons to stimulation of the above-mentioned formations were found to be similar. It is concluded that the optic radiation contains three principal groups of fibers with conduction velocities of 28.5–16.6, 11.7–8.9, and 7.4–6.0 m/sec, respectively.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 7, No. 6, pp. 589–596, November–December, 1975.