Spatial organization of visual messages of the rabbit's cerebellar flocculus. I. Typology of inferior olive neurons of the dorsal cap of Kooy

1988 ◽  
Vol 60 (6) ◽  
pp. 2073-2090 ◽  
Author(s):  
C. S. Leonard ◽  
J. I. Simpson ◽  
W. Graf

1. Single-unit responses to large-field visual stimuli were recorded extracellularly from neurons in the dorsal cap of Kooy of the inferior olive in anesthetized, paralyzed rabbits. The visually modulated neurons in the dorsal cap responded optimally to slow rotation of random dot stimuli, which were produced using handheld patterns or a planetarium projector. 2. Neurons had either monocular or binocular receptive fields. For binocular receptive field neurons, monocular stimulation of one eye, called the dominant eye, elicited greater modulation than did stimulation of the other eye. Rotation about a particular axis, called the preferred axis, produced both maximal excitation and inhibition. On the basis of differences in preferred axis orientation and in eye dominance, three neuron classes called Vertical Axis, Anterior (45 degrees) Axis, and Posterior (135 degrees) Axis were distinguished. 3. Vertical Axis neurons were modulated exclusively from the eye contralateral to the inferior olive recording site. This cell type responded strongly to large-field visual stimuli rotating about the vertical axis. Excitation resulted from movement in the temporal to nasal direction, and inhibition occurred during movement in the nasal to temporal direction. 4. Two subclasses of Anterior (45 degrees) Axis neurons were distinguished according to whether the receptive field was monocular or binocular. For both subclasses, the dominant eye was ipsilateral. The receptive field organization of the dominant eye was bipartite as described in the previous paper (51) for neurons in the midbrain visual tegmental relay zone. Anterior (45 degrees) Axis neurons were maximally excited when the stimulus pattern moved upward and posterior above the horizon in the anterior quadrant of the ipsilateral visual field, from 0 degrees (nose) to approximately 45 degrees azimuth. From 45 to 180 degrees azimuth (occiput) and above the horizon, these neurons were excited by downward and posterior movement. Inhibition occurred with oppositely directed movements. For rotating stimuli presented to the dominant eye, this class of neurons responded best to rotation of the visual world about an axis oriented near the horizontal plane and approximately 45 degrees azimuth. 5. The receptive field of Posterior (135 degrees) Axis neurons was always binocular, with the dominant eye contralateral. For the contralateral receptive field, from 0 degree (nose) to 135 degrees azimuth and above the horizon, excitation occurred during upward and posterior movement.(ABSTRACT TRUNCATED AT 400 WORDS)

1988 ◽  
Vol 60 (6) ◽  
pp. 2091-2121 ◽  
Author(s):  
W. Graf ◽  
J. I. Simpson ◽  
C. S. Leonard

1. Complex and simple spike responses of Purkinje cells were recorded in the flocculus of anesthetized, paralyzed rabbits during rotating full-field visual stimuli produced by a three-axis planetarium projector. 2. On the basis of the spatial properties of their complex spike responses, floccular Purkinje cells could be placed into three distinct classes called Vertical Axis, Anterior (45 degrees) Axis and Posterior (135 degrees) Axis. The first two classes occurred in both monocular and binocular forms; the third class was encountered only in binocular form. For the binocular response forms, stimulation through one eye, called the dominant eye, elicited a stronger modulation of the complex spike firing rate than did stimulation of the other eye. The approximate orientation of that axis about which full-field rotation elicited the deepest modulation (the preferred axis) when presented to the dominant eye served as the class label. These classes are the same as those determined qualitatively for inferior olive neurons in the previous paper (47). The present study provides a quantitative description of their spatial tuning. 3. For Vertical Axis cells, the dominant eye was ipsilateral with respect to the flocculus recording site. The preferred axis was vertical and null (no-response) axes were in the horizontal plane. For the binocular response form of Vertical Axis cells (less than 10% of this class), the direction preferences for the two eyes were synergistic with respect to rotation about the vertical axis. 4. The dominant eye for the Anterior (45 degrees) Axis cells was contralateral, with the preferred axis oriented in the horizontal plane at approximately 45 degrees contralateral azimuth. The modulation depth showed a close to cosine relation with the angle between the preferred axis and the stimulus rotation axis. The average orientation (n = 10) for the dominant eye preferred axis, determined by the best-fit sinusoid, was 47 degrees contralateral azimuth. The preferred axis orientation for the ipsilateral (nondominant) eye in the binocular response forms was between 45 and 90 degrees azimuth in the horizontal plane. A null axis for each eye was at approximately 90 degrees to the preferred axis. 5. The Posterior (135 degrees) Axis cells were encountered only in binocular response forms. The dominant eye was ipsilateral, with the preferred axis oriented at approximately 135 degrees ipsilateral azimuth close to the horizontal plane. The modulation depth showed a close to cosine relation with the angle between the preferred axis and the stimulus rotation axis.(ABSTRACT TRUNCATED AT 400 WORDS)


1988 ◽  
Vol 60 (6) ◽  
pp. 2055-2072 ◽  
Author(s):  
J. I. Simpson ◽  
C. S. Leonard ◽  
R. E. Soodak

1. To compare the spatial organization of the direction selectivity of neurons in the medial terminal nucleus (MTN) of the accessory optic system with that of neurons in the adjacent ventral tegmentum, extracellular single-unit recordings were made in the anesthetized rabbit. The ventral tegmental neurons were located in a region called the visual tegmental relay zone (VTRZ), which is defined by the ventral tegmental terminal field of contralaterally projecting MTN neurons. 2. Some of the present sample of MTN neurons (5 of 34) had monocular receptive fields composed of two parts distinguished by a marked difference in the orientation of their respective direction-selective tuning curves. For one part of the receptive field the preferred excitatory direction was "up," while for the other part it was "down." Such receptive fields for one eye were called bipartite, whereas the more usually encountered MTN receptive fields, which could be characterized by a single direction-selective tuning curve, were called uniform. 3. Of the 16 neurons recorded from the VTRZ, all but one were binocular. For these neurons, both uniform and bipartite receptive fields were found for each eye alone. The only monocular neuron encountered in the VTRZ had a contralateral, bipartite receptive field. 4. The spatial organization of the direction selectivity of bipartite receptive fields strongly suggests that they are suited to represent rotation of the visual field about a horizontal axis located in the vertical plane that divides the receptive field into two parts. 5. The boundary between the two parts of the bipartite receptive fields was found using handheld visual stimuli at one of two azimuthal locations, either close to 45 degrees or between 95 and 125 degrees (the 0 degree reference was rostral in the midsagittal plane). This particular structure of the bipartite receptive fields suggests that their preferred rotation axes have a close spatial relation to the best-response axes of the semicircular canals. 6. Seven VTRZ neurons were antidromically activated by electrical stimulation of the ipsilateral dorsal cap of the inferior olive. Since the receptive fields of VTRZ neurons have many of the structural features characteristic of the receptive fields of rostral dorsal cap neurons we conclude that the spatial organization of the receptive fields of dorsal cap neurons is, for the most part, synthesized prior to the inferior olive.(ABSTRACT TRUNCATED AT 400 WORDS)


1988 ◽  
Vol 60 (2) ◽  
pp. 604-620 ◽  
Author(s):  
W. T. Newsome ◽  
R. H. Wurtz ◽  
H. Komatsu

1. We investigated cells in the middle temporal visual area (MT) and the medial superior temporal area (MST) that discharged during smooth pursuit of a dim target in an otherwise dark room. For each of these pursuit cells we determined whether the response during pursuit originated from visual stimulation of the retina by the pursuit target or from an extraretinal input related to the pursuit movement itself. We distinguished between these alternatives by removing the visual motion stimulus during pursuit either by blinking off the visual target briefly or by stabilizing the target on the retina. 2. In the foveal representation of MT (MTf), we found that pursuit cells usually decreased their rate of discharge during a blink or during stabilization of the visual target. The pursuit response of these cells depends on visual stimulation of the retina by the pursuit target. 3. In a dorsal-medial region of MST (MSTd), cells continued to respond during pursuit despite a blink or stabilization of the pursuit target. The pursuit response of these cells is dependent on an extraretinal input. 4. In a lateral-anterior region of MST (MST1), we found both types of pursuit cells; some, like those in MTf, were dependent on visual inputs whereas others, like those in MSTd, received an extraretinal input. 5. We observed a relationship between pursuit responses and passive visual responses. MST cells whose pursuit responses were attributable to extraretinal inputs tended to respond preferentially to large-field random-dot patterns. Some cells that preferred small spots also had an extraretinal input. 6. For 92% of the pursuit cells we studied, the pursuit response began after onset of the pursuit eye movement. A visual response preceding onset of the eye movement could be observed in many of these cells if the initial motion of the target occurred within the visual receptive field of the cell and in its preferred direction. In contrast to the pursuit response, however, this visual response was not dependent on execution of the pursuit movement. 7. For the remaining 8% of the pursuit cells, the pursuit discharge began before initiation of the pursuit eye movement. This occurred even though the initial motion of the target was outside the receptive field as mapped during fixation trials. Our data suggest, however, that such responses may be attributable to an expansion of the receptive field that accompanies enhanced visual responses.(ABSTRACT TRUNCATED AT 400 WORDS)


1980 ◽  
Vol 43 (3) ◽  
pp. 807-831 ◽  
Author(s):  
G. W. Davis ◽  
K. Naka

1. Receptive-field profiles of catfish (Ictalurus punctatus) retinal neurons were produced by a moving single bar or a moving random grating, which was swept across the cell's receptive field at a constant speed. 2. Bipolar cells form either an on- or an off-center biphasic field and are approximately linear in time and space. 3. Type-C or transient cells form predominantly monotonic receptive fields. We find two subclasses, one slow and the other fast transient cells. They can be identified functionally as well as morphologically. 4. Type-N or sustained cells form a biphasic receptive field, which is revealed by a bar of light. The monotonic field found by a spot or an annulus of light represents activity of the cell's field center. 5. There are two ganglion-cell types, small-field cells and large-field cells. It appears as if small-field cells copy signals in the bipolar cells and large-field cells, signals in the type-N cells. We suggest, however, that this observation represents the limitation imposed by our stimuli rather than an overall functional characteristic of catfish ganglion cells.


2021 ◽  
Author(s):  
Rita Felix ◽  
Daniil A Markov ◽  
Sabine L Renninger ◽  
Raquel Tomas ◽  
Alexandre Laborde ◽  
...  

The olivo-cerebellar system plays an important role in vertebrate sensorimotor control. According to a classical theory of cerebellar cortex, the inferior olive (IO) provides Purkinje cells with error information which drives motor learning in the cerebellum. Here we investigate the sensory representations in the IO of larval zebrafish and their spatial organization. Using single-cell labeling of genetically identified IO neurons we find that they can be divided into at least two distinct groups based on their spatial location, dendritic morphology, and axonal projection patterns. In the same genetically targeted population, we recorded calcium activity in response to a set of visual stimuli using 2-photon imaging. We found that most IO neurons showed direction selective and binocular responses to visual stimuli and that functional properties were spatially organized within the IO. Light-sheet functional imaging that allowed for simultaneous activity recordings at the soma and axonal level revealed tight coupling between soma location, axonal projections and functional properties of IO neurons. Taken together, our results suggest that anatomically-defined classes of inferior olive neurons correspond to distinct functional types, and that topographic connections between IO and cerebellum contribute to organization of the cerebellum into distinct functional zones.


1996 ◽  
Vol 76 (3) ◽  
pp. 1439-1456 ◽  
Author(s):  
P. Mazzoni ◽  
R. M. Bracewell ◽  
S. Barash ◽  
R. A. Andersen

1. The lateral intraparietal area (area LIP) of the monkey's posterior parietal cortex (PPC) contains neurons that are active during saccadic eye movements. These neurons' activity includes visual and saccade-related components. These responses are spatially tuned and the location of a neuron's visual receptive field (RF) relative to the fovea generally overlaps its preferred saccade amplitude and direction (i.e., its motor field, MF). When a delay is imposed between the presentation of a visual stimulus and a saccade made to its location (memory saccade task), many LIP neurons maintain elevated activity during the delay (memory activity, M), which appears to encode the metrics of the next intended saccadic eye movements. Recent studies have alternatively suggested that LIP neurons encode the locations of visual stimuli regardless of where the animal intends to look. We examined whether the M activity of LIP neurons specifically encodes movement intention or the locations of recent visual stimuli, or a combination of both. In the accompanying study, we investigated whether the intended-movement activity reflects changes in motor plan. 2. We trained monkeys (Macaca mulatta) to memorize the locations of two visual stimuli and plan a sequence of two saccades, one to each remembered target, as we recorded the activity of single LIP neurons. Two targets were flashed briefly while the monkey maintained fixation; after a delay the fixation point was extinguished, and the monkey made two saccades in sequence to each target's remembered location, in the order in which the targets were presented. This "delayed double saccade" (DDS) paradigm allowed us to dissociate the location of visual stimulation from the direction of the planned saccade and thus distinguish neuronal activity related to the target's location from activity related to the saccade plan. By imposing a delay, we eliminated the confounding effect of any phasic responses coincident with the appearance of the stimulus and with the saccade. 3. We arranged the two visual stimuli so that in one set of conditions at least the first one was in the neuron's visual RF, and thus the first saccade was in the neuron's motor field (MF). M activity should be high in these conditions according to both the sensory memory and motor plan hypotheses. In another set of conditions, the second stimulus appeared in the RF but the first one was presented outside the RF, instructing the monkey to plan the first saccade away from the neuron's MF. If the M activity encodes the motor plan, it should be low in these conditions, reflecting the plan for the first saccade (away from the MF). If it is a sensory trace of the stimulus' location, it should be high, reflecting stimulation of the RF by the second target. 4. We tested 49 LIP neurons (in 3 hemispheres of 2 monkeys) with M activity on the DDS task. Of these, 38 (77%) had M activity related to the next intended saccade. They were active in the delay period, as expected, if the first saccade was in their preferred direction. They were less active or silent if the next saccade was not in their preferred direction, even when the second stimulus appeared in their RF. 5. The M activity of 8 (16%) of the remaining neurons specifically encoded the location of the most recent visual stimulus. Their firing rate during the delay reflected stimulation of the RF independently of the saccade being planned. The remaining 3 neurons had M activity that did not consistently encode either the next saccade or the stimulus' location. 6. We also recorded the activity of a subset of neurons (n = 38) in a condition in which no stimulus appeared in a neuron's RF, but the second saccade was in the neuron's MF. In this case the majority of neurons tested (23/38, 60%) became active in the period between the first and second saccade, even if neither stimulus had appeared in their RF. Moreover, this activity appeared only after the first saccade had started in all but two of


1990 ◽  
Vol 63 (3) ◽  
pp. 502-522 ◽  
Author(s):  
R. Lal ◽  
M. J. Friedlander

1. Extracellular recordings were made from single neurons in layer A of the left dorsal lateral geniculate nucleus (LGNd) of anesthetized and paralyzed adult cats. Responses to retinotopically identical visual stimuli (presented through the right eye) were recorded at several positions of the left eye in its orbit. Visual stimuli consisted of drifting sinusoidal gratings of optimal temporal and spatial frequencies at twice threshold contrast. Visual stimulation of the left eye was blocked by a variety of methods, including intravitreal injection of tetrodotoxin (TTX). The change in position of the left eye was achieved by passive movements in a randomized and interleaved fashion. Of 237 neurons studied, responses were obtained from 143 neurons on 20-100 trials of identical visual stimulation at each of six eye positions. Neurons were classified as X- or Y- on the basis of a standard battery of physiological tests (primarily linearity of spatial summation and response latency to electrical stimulation of the optic chiasm). 2. The effect of eye position on the visual response of the 143 neurons was analyzed with respect to the number of action potentials elicited and the peak firing rate. Fifty-seven (40%) neurons had a significant effect [by one-factor repeated-measure analysis of variance (ANOVA), P less than 0.05] of eye position on the visual response by either criterion (number of action potentials or peak firing rate). Of these 57 neurons, 47 had a significant effect (P less than 0.05) with respect to the number of action potentials and 23 had a significant effect (P less than 0.05) by both criteria. Thus the permissive measure by either criterion and the conservative measure by both criteria resulted in 40% and 16%, respectively, of all neurons' visual responses being significantly affected by eye position. 3. For the 47 neurons with a significant effect of eye position (number of action potentials criterion), a trend analysis of eye position versus visual response showed a linear trend (P less than 0.05) for 9 neurons, a quadratic trend (P less than 0.05) for 32 neurons, and no significant trend for the 6 remaining neurons. The trends were approximated with linear and nonlinear gain fields (range of eye position change over which the visual response was modulated). The gain fields of individual neurons were compared by measuring the normalized gain (change in neuronal response per degree change of eye position). The mean normalized gain for the 47 neurons was 4.3. 4. The nonlinear gain fields were generally symmetric with respect to nasal versus temporal changes in eye position.(ABSTRACT TRUNCATED AT 400 WORDS)


1996 ◽  
Vol 75 (6) ◽  
pp. 2441-2450 ◽  
Author(s):  
D. D. Rasmusson

1. Single neurons in the ventroposterior lateral thalamic nucleus were studied in 10 anesthetized raccoons, 4 of which had undergone amputation of the fourth digit 4-5 mo before recording. Neurons with receptive fields on the glabrous skin of a forepaw digit were examined in response to electrical stimulation of the “on-focus” digit that contained the neuron's receptive field and stimulation of an adjacent, “off-focus” digit. 2. In normal raccoons all neurons responded to on-focus stimulation with an excitation at a short latency (mean 13 ms), whereas only 63% of the neurons responded to off-focus digit stimulation. The off-focus responses had a longer latency (mean 27.2 ms) and a higher threshold than the on-focus responses (800 and 452 microA, respectively). Only 3 of 32 neurons tested with off-focus stimulation had both a latency and a threshold within the range of on-focus values. Inhibition following the excitation was seen in the majority of neurons with both types of stimulation. 3. In the raccoons with digit removal, the region of the thalamus that had lost its major peripheral input (the “deafferented” region) was distinguished from the normal third and fifth digit regions on the basis of the sequence of neuronal receptive fields within a penetration and receptive field size as described previously. 4. Almost all of the neurons in the deafferented region (91%) were excited by stimulation of one or both adjacent digits. The average latency for these responses was shorter (15.3 ms) and the threshold was lower than was the case with off-focus stimulation in control animals. These values were not significantly different from the responses to on-focus stimulation in the animals with digit amputation. 5. These results confirm that reorganization of sensory pathways can be observed at the thalamic level. In addition to the changes in the somatotopic map that have been shown previously with the use of mechanical stimuli, the present paper demonstrates an improvement in several quantitative measures of single-unit responses. Many of these changes suggest that this reorganization could be explained by an increased effectiveness of preexisting, weak connections from the off-focus digits; however, the increase in the proportion of neurons responding to stimulation of adjacent digits may indicate that sprouting of new connections also occurs.


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