Cells of the striate cortex projecting to the Clare-Bishop area of the cat

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411

SUMMARY1. We have studied the neuronal circuitry and structure-function relationships of single neurones in the striate visual cortex of the cat using a combination of electrophysiological and anatomical techniques.2. Glass micropipettes filled with horseradish peroxidase were used to record extracellularly from single neurones. After studying the receptive field properties, the afferent inputs of the neurones were studied by determining their latency of response to electrical stimulation at different positions along the optic pathway. Some cells were thus classified as receiving a mono-or polysynaptic input from afferents of the lateral geniculate nucleus (l.g.n.), via X-or Y-like retinal ganglion cells.3. Two striking correlations were found between dendritic morphology and receptive field type. All spiny stellate cells, and all star pyramidal cells in layer 4A, had receptive fields with spatially separate on and off subfields (S-type receptive fields). All the identified afferent input to these, the major cell types in layer 4, was monosynaptic from X-or Y-like afferents.4. Neurones receiving monosynaptic X-or Y-like input were not strictly segregated in layer 4 and the lower portion of layer 3. Nevertheless the X-and Y-like l.g.n. fibres did not converge on any of the single neurones so far studied.5. Monosynaptic input from the l.g.n. afferents was not restricted to cells lying within layers 4 and 6, the main termination zones of the l.g.n. afferents, but was also received by cells lying in layers 3 and 5.6. The projection pattern of cells receiving monosynaptic input differed widely, depending on the laminar location of the cell soma. This suggests the presence of a number of divergent paths within the striate cortex.7. Cells receiving indirect input from the l.g.n. afferents were located mainly within layers 2, 3 and 5. Most pyramidal cells in layer 3 had axons projecting out ofthe striate cortex, while many axons of the layer 5 pyramids did not.8. The layer 5 cells showed the most morphological variation of any layer, were the most difficult to activate by electrical stimulation, and contained some cells which responded with the longest latencies of any cells in the striate cortex. This suggests that they were several synapses distant from the J.g.n. input.9. The majority of cells in layers 2, 3, 4 and 6 had the same basic S-type receptive field structure.

Section: Discussionmentioning

confidence: 73%

Section: Relationship Of Receptive Field To Neuronal Typementioning

confidence: 99%

Form, function and intracortical projections of spiny neurones in the striate visual cortex of the cat.

Martin¹,

Whitteridge²

1984

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411

“…Quantitative comparison of directional selectivity for oriented stimuli and textured backgrounds, presented separately or together, was confined to cells strongly sensitive to texture motion. This effectively excluded all simple cells, together with the B cells (Henry, Lund & Harvey, 1978) amongst Gilbert's 'standard' category (complex cells with marked length summation; Gilbert, 1977). End-stopped members of both classes of cells (hypercomplex types I and II, respectively, of Dreher, 1972), were also virtually excluded because of their poor response to any stimulus of large areal extent, including fields of random texture.…”

Section: Resultsmentioning

confidence: 99%

Directional tuning interactions between moving oriented and textured stimuli in complex cells of feline striate cortex.

Hammond¹,

Smith²

1983

SUMMARY1. In sixty-five complex cells recorded from striate cortex of lightly anaesthetized, paralysed cats we investigated directional selectivity for motion of oriented and textured stimuli, both alone and when-moving simultaneously in the same direction and at the same velocity. Monocular comparisons were made over a range of velocities for the dominant eye in all cells, and for the other eye in fourteen instances.2. For oriented stimuli, response magnitude varied with velocity, but preferred directions(s) and sharpness of tuning remained constant. For background texture motion, directional selectivity was typically unimodal at low velocities, but became increasingly bimodal at high velocities: a trough of depressed response (in directions optimal for oriented stimuli) separated two progressively more widely disparate preferred directions. Preferred velocity and velocity bandpass were typically higher for texture than for bar motion.3. Directional tuning interactions revealed no important class-or layer-specific differences and were similar for each monocular input.4. Results for bar and texture combinations moving in unison could not be predicted from selectivity for each stimulus alone. At all velocities they closely resembled those for bar motion alone. Tuning curves for the combination stimulus were only marginally broader than those for oriented stimuli: much sharper and totally different in profile from those for texture.5. It is concluded that an oriented stimulus in motion induces potent blockade of complex-cell sensitivity to moving textured backgrounds. Complex cells insensitive to relative motion between objects and backgrounds (Hammond & Smith, 1982a, 1983b) may thus be excellent candidates for resolving motion of objects regardless of the context in which they are seen.

“…12B (Smith & Spear, 1979) or early ablation of the more medial visual cortex (Tong et al 1984 (Symonds & Rosenquist, 1984b). Henry, Lund & Harvey (1978) found that almost all those neurones recorded in area 17 that could be antidromically activated from p.m.l.s. lay in layer III and were orientationselective complex cells.…”

Section: Qualitative Analysis Of Stimulus Selectivitymentioning

confidence: 99%

Stimulus selectivity and functional organization in the lateral suprasylvian visual cortex of the cat.

Blakemore¹,

Zumbroich²

1987

SUMMARY1. We have examined the responses of cells in the postero-medial and posterolateral lateral suprasylvian areas (p.m.l.s./p.l.l.s.) in the medial and lateral banks of the middle suprasylvian sulcus of the anaesthetized, paralysed cat.2. Visual responses were assessed qualitatively (for projected spot and bar stimuli) and quantitatively (for drifting, high-contrast gratings of optimum spatial and temporal frequencies, but varying in orientation and direction of drift). There was excellent agreement between qualitative and quantitative estimates of preferred direction of motion.3. Comparison of responses to motion in the preferred direction and the opposite direction confirmed that the percentage of units with strong directional preference is higher in this region of cortex than in other cortical and subcortical visual structures so far investigated.4. Cells were comparatively well 'tuned' for the direction of motion of a grating: on average the half-width at half-amplitude for the variation in response around the principal preferred direction was 23-2 deg for p.m.l.s. and 25-3 deg for p.l.l.s., thus falling within the range found for complex cells in area 17. In this and other aspects of their direction selectivity, neurones in p.m.l.s. and p.l.l.s. were very similar to each other.5. Quantitative analysis of the direction-response functions revealed them frequently to be more complex than previously described. For many cells there were subsidiary response peaks in addition to the main peak at the principal preferred direction. Often there was an accessory peak 180 deg from the optimum direction (i.e. directional preference was incomplete), but there was also a clear tendency for responses to be specifically elevated for directions orthogonal to the principal direction.6. Tests with stationary, contrast-modulated gratings of the optimum spatial frequency, but differing in orientation, revealed that neurones responsive to such stimuli (though limited to about half the population) were orientation selective, their preferred orientations for stationary and drifting gratings being very similar.7. The functional architecture of the lateral suprasylvian cortex was studied by means of single and multiple penetrations at different angles to the cortical surface: in most penetrations in p.m.l.s. the preferred directions of cells tended to shift progressively in small steps across the cortex, at a maximum rate of about 360 deg C. BLAKEMORE AND T. J. ZUMBROICH mm-'. However, there were occasional 180 deg differences between neighbouring recording sites or between cells recorded at different depths within a single radial column. Thus, the local sequential representation across the cortical surface seems to relate to stimulus orientation or axis of motion, rather than to the direction of movement.