Sensitivity profile for orientation selectivity in the visual cortex of goggle-reared mice

It has been widely accepted that ocular dominance in the responses of visual cortical neurons can change depending on visual experience in a postnatal period. However, experience-dependent plasticity for orientation selectivity, which is another important response property of visual cortical neurons, is not yet fully understood. To address this issue, using intrinsic signal imaging and two-photon calcium imaging we attempted to observe the alteration of orientation selectivity in the visual cortex of juvenile and adult mice reared with head-mounted goggles, through which animals can experience only the vertical orientation. After one week of goggle rearing, the density of neurons optimally responding to the exposed orientation increased, while that responding to unexposed orientations decreased. These changes can be interpreted as a reallocation of preferred orientations among visually responsive neurons. Our obtained sensitivity profile for orientation selectivity showed a marked peak at 5 weeks and sustained elevation at 12 weeks and later. These features indicate the existence of a critical period between 4 and 7 weeks and residual orientation plasticity in adult mice. The presence of a dip in the sensitivity profile at 10 weeks suggests that different mechanisms are involved in orientation plasticity in childhood and adulthood.     

Neural coding of 3D features of objects for hand action in the parietal cortex of the monkey.

In our previous studies of hand manipulation task-related neurons, we found many neurons of the parietal association cortex which responded to the sight of three-dimensional (3D) objects. Most of the task-related neurons in the AIP area (the lateral bank of the anterior intraparietal sulcus) were visually responsive and half of them responded to objects for manipulation. Most of these neurons were selective for the 3D features of the objects. More recently, we have found binocular visual neurons in the lateral bank of the caudal intraparietal sulcus (c-IPS area) that preferentially respond to a luminous bar or place at a particular orientation in space. We studied the responses of axis-orientation selective (AOS) neurons and surface-orientation selective (SOS) neurons in this area with stimuli presented on a 3D computer graphics display. The AOS neurons showed a stronger response to elongated stimuli and showed tuning to the orientation of the longitudinal axis. Many of them preferred a tilted stimulus in depth and appeared to be sensitive to orientation disparity and/or width disparity. The SOS neurons showed a stronger response to a flat than to an elongated stimulus and showed tuning to the 3D orientation of the surface. Their responses increased with the width or length of the stimulus. A considerable number of SOS neurons responded to a square in a random dot stereogram and were tuned to orientation in depth, suggesting their sensitivity to the gradient of disparity. We also found several SOS neurons that responded to a square with tilted or slanted contours, suggesting their sensitivity to orientation disparity and/or width disparity. Area c-IPS is likely to send visual signals of the 3D features of an object to area AIP for the visual guidance of hand actions.     

Reciprocal Interaction of On- and Off-Systems as a Mechanism of Sensitivity of Visual Neurons to The Orientation of the Vector of the Brightness Gradient in Cats

An experimental study has been performed on neuronal mechanisms of sensitivity of cat visual neurons (lateral geniculate body) to the value and orientation of the vector of brightness gradient in a test stimulus. With changes of the value and orientation of the brightness gradient vector, there exists an optimal (preferred) orientation of the gradient vector, at which the neuronal response is maximal. The sensitivity of neurons to the brightness gradient at shifts of the gradient vector towards the preferred orientation increases not due to an increased excitation in neuronal reactions, but due to a reduction of reciprocal (on- and off-) inhibition, affecting this neuron, of adjacent neurons in neuronal pools. The reciprocal inhibitory interaction of on- and off-systems is enhanced by inhibiting the response of the antagonistic neuron at shifts of the brightness gradient vector in the stimulus from the preferred to the non-preferred orientation. This reciprocal inhibitory interaction is clearly seen in pairs of on- and off-neurons with superposed receptive fields (RF) at their simultaneous analysis of on- and off-responses at a change of the orientation of the brightness gradient vector by 180 degrees. Dependencies of the parameters (duration and intensity of inhibitory phases in responses) of reciprocal inhibitory interaction on orientation of the brightness gradient vector in RF of neurons are determined. Dependencies of responses of the total sample of neurons, which are plotted for on- and off-neurons, to their adequate and inadequate (on- and off-) stimuli on the orientation of the brightness gradient vector are inversely proportional.     

Selective sensitivity of the cat striate neurons to cruciform and angular figures of various orientations

Selectivity and invariability of tuning were studied in 51 neurons of the primary visual cortex (area 17); cruciform and angular figures (CF and AF, respectively) of different configurations and orientations were presented in their receptive fields. Twenty-three neurons, or 45% of the studied cells, demonstrated selective sensitivity to these figures. Their responses considerably (2.38±0.36 times, on average) increased, as compared with those evoked by presentation of a single bar of preferred orientation. In the examined group, 2 cells demonstrated sensitivity both to the CF and AF. A wide range of detector properties related to the CF and AF analysis was found in the analyzed neuronal population. Detectors of configuration of these figures are described. Selective sensitivity to the angle between branches of these figures was observed in 17 neurons, and responses of 2 neurons among them showed invariability to orientation of these figures. Four cells were selective for orientation and were insensitive to configuration, and 4 other cells showed no specific sensitivity to either of these properties, but were sensitive to the appearance of a CF itself in their receptive field (these cells were regarded as invariant detectors of crossing nodes). Data inconsistent with the hierarchic principle of detection of the above properties are presented. Possible mechanisms and functional significance of selective sensitivity of striate neurons to the CF and AF are discussed.Neirofiziologiya/Neurophysiology, Vol. 27, No. 5/6, pp. 403–412, September–December, 1995.     

视觉剥夺猫外膝体神经元最优方位的分布特性

记录和测定了视觉剥夺猫（ｄａｒｋ－ｒｅａｒｅｄｃａｔｓ）外膝体３４４个细胞的方位调谐等感受野特性,多数细胞（８２％）具有方位敏感性（Ｂｉａｓ＞０．１）。最优方位的分布与正常猫类似,偏向于水平方位,但分布特性强于正常猫。与正常猫类似,视觉剥夺猫外膝体细胞的最优方位与该细胞感受野在视网膜上的位置有关,偏向平行于视网膜中心区与感受野中心的连线（向心线）;外膝体内位置相邻近的细胞具有相近的最优方位,亦呈现初步有序排列。结果表明：外膝体细胞最优方位的分布特性与后天视觉经验无关而可能来源于遗传因素。     

Stereopsis and the random element in the organization of the striate cortex.

Receptive field position and orientation disparities are both properties of binocularly discharged striate neurons. Receptive field position desparities have been used as a key element in the neural theory for binocular depth discrimination. Since most striate cells in the cat are binocular, these position disparities require that cells immediately adjacent to one another in the cortex should show a random scatter in their monocular receptive field positions. Superimposed on the progressive topographical representation of the visual field on the striate cortex there is experimental evidence for a localized monocular receptive field position scatter. The suggestion is examined that the binocular position disparities are built up out of the two monocular position scatters. An examination of receptive field orientation disparities and their relation to the random variation in the monocular preferred orientations of immediately adjacent striate neurons also leads to the conclusion that binocular orientation disparities are a consequence of the two monocular scatters. As for receptive field position, the local scatter in preferred orientation is superimposed on a progressive representation of orientation over larger areas of the cortex. The representation in the striate cortex of visual field position and of stimulus orientation is examined in relation to the correlation between the disparities in receptive field position and preferred orientation. The role of orientation disparities in binocular vision is reviewed.     

Activation of orientation selectivity mechanisms in neurons of the cat visual cortex by a moving visual "noise" field

A relationship was established between the response of neurons of the cat visual cortex and the direction of movement in the visual "noise" field and of a slit of light. It was shown that a shift in the preferred direction of movement in the "noise" field in relation to that of the slit was found in orientationally selective neurons only. It was concluded that the "noise" field, which is a stimulus lacking an orientation component, does activate mechanisms of neuronal orientation selectively.V. Kapsukas State University, Vilnius. Translated from Neirofiziologiya, Vol. 17, No. 5, pp. 596–601, September–October, 1985.     

Dynamics of orientation selectivity in the primary visual cortex and the importance of cortical inhibition

To test theories of orientation selectivity in primary visual cortex (V1), we have done experiments to measure the dynamics of orientation tuning of single neurons in the V1 cortex of macaque monkeys. Based on our dynamics results, we propose that a V1 cell's orientation selectivity is generated mainly by both tuned enhancement and global suppression. Enhancement near the preferred orientation is probably caused by feed-forward input from LGN (plus amplification by cortical-cortical interaction). Global suppression could be supplied by cortical inhibition. Additionally, in about 1/3 of V1 neurons (usually the most sharply tuned) there is tuned suppression, centered near the cell's preferred orientation but broader than tuned enhancement. These mechanisms also can explain important features of steady-state selectivity in the V1 neuron population. Furthermore, similar neuronal mechanisms may be used generally throughout the cerebral cortex.     

The tuning of striate neurons to cross-like figures during local blockade of intracortical inhibition]

Many neurons in the cat primary visual cortex reveal sensitivity to cruciform and corner figures as well as to local orientation discontinuities. We investigated this sensitivity in 85 V1 neurons before and after the local blockade of GABA(A)ergic inhibition by microiontophoretic application of bicuculline and observed two opposite effects: a decrease or disappearance of sensitivity to crosses in about half of the neurons and its increase or appearance in about one third of the units. The results indicate substantial and drastically different contribution of intracortical inhibition to sensitivity to line-crossings in the visual cortical neurons. Some possible mechanisms of this difference are discussed.     

Orientation-selective neurons in the squirrel visual cortex

The organization of receptive fields of neurons sensitive to orientation of visual stimuli was investigated in the squirrel visual cortex. Neurons with mutually inhibitory on- and off-areas of the receptive field, with partially and completely overlapping excitatory and inhibitory mechanisms, were distinguished. Neurons of the second group are most typical. They exhibit orientation selectivity within the excitatory area of the receptive field because, if the stimulus widens in the zero direction, perpendicular to the preferred direction, lateral inhibition is much stronger than if it widens in the preferred direction. Additional inhibitory areas (outside the excitatory area) potentiate this inhibition and increase selectivity. It is suggested that there is no strict separation of simple (with separate excitatory and inhibitory mechanisms in the receptive field) and complex (with overlapping of these mechanisms) neurons in the squirrel visual cortex.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 11, No. 6, pp. 540–549, November–December, 1979.     

Responses of Neurons of the Extrastriate Area 21b of the Cat Brain Cortex to Changes in Orientation of Moving Visual Stimuli

We studied the responses of neurons of the extrastriate cortical area 21b of the cat to changes in orientation of the movements of visual stimuli within the receptive field (RF) of the neuron under study. Our experiments demonstrated that 24 of 108 cells (22%) responded differentially to a certain extent to orientation of the movements of visual stimuli. As a whole, neurons of the area 21b did not demonstrate fine tuning on the optimum angle of orientation. In many cases, neuronal responses to different orientations of the movement of visual stimulus depended significantly on specific parameters of this stimulus (its shape, dimensions, and contrast). Some directionally sensitive neurons responded to a change in orientation of the movement of visual stimuli by modification of the index of directionality. We also studied spatial organization of the RF of neurons with the presentation of stationary visual stimuli. Comparison of the neuronal responses to a change in orientation of the movements of stimuli and to presentation of stationary stimuli showed that the correlation between the orientation sensitivity of the neuron under study and the stationary functional organization of its RF was insignificant. We hypothesize that inhibitory processes and subthreshold influences from a space surrounding the RF play a special role in the formation of the neuronal responses generated in the associative visual cortical regions to visual stimulation.     

Similarity of visual selectivity among clonally related neurons in visual cortex

Neurons in rodent visual cortex are organized in a salt-and-pepper fashion for orientation selectivity, but it is still unknown how this functional architecture develops. A recent study reported that the progeny of single cortical progenitor cells are preferentially connected in the postnatal cortex. If these neurons acquire similar selectivity through their connections, a salt-and-pepper organization may be generated, because neurons derived from different progenitors are intermingled in rodents. Here we investigated whether clonally related cells have similar preferred orientation by using a transgenic mouse, which labels all the progeny of single cortical progenitor cells. We found that preferred orientations of clonally related cells are similar to each other, suggesting that cell lineage is involved in the development of response selectivity of neurons in the cortex. However, not all clonally related cells share response selectivity, suggesting that cell lineage is not the only determinant of response selectivity.     

Visual cells remember earlier applied target: plasticity of orientation selectivity

Background

A canonical proposition states that, in mature brain, neurons responsive to sensory stimuli are tuned to specific properties installed shortly after birth. It is amply demonstrated that that neurons in adult visual cortex of cats are orientation-selective that is they respond with the highest firing rates to preferred oriented stimuli.

Methodology/Principal Findings

In anesthetized cats, prepared in a conventional fashion for single cell recordings, the present investigation shows that presenting a stimulus uninterruptedly at a non-preferred orientation for twelve minutes induces changes in orientation preference. Across all conditions orientation tuning curves were investigated using a trial by trial method. Contrary to what has been previously reported with shorter adaptation duration, twelve minutes of adaptation induces mostly attractive shifts, i.e. toward the adapter. After a recovery period allowing neurons to restore their original orientation tuning curves, we carried out a second adaptation which produced three major results: (1) more frequent attractive shifts, (2) an increase of their magnitude, and (3) an additional enhancement of responses at the new or acquired preferred orientation. Additionally, we also show that the direction of shifts depends on the duration of the adaptation: shorter adaptation in most cases produces repulsive shifts, whereas adaptation exceeding nine minutes results in attractive shifts, in the same unit. Consequently, shifts in preferred orientation depend on the duration of adaptation.

Conclusion/Significance

The supplementary response improvements indicate that neurons in area 17 keep a memory trace of the previous stimulus properties, thereby upgrading cellular performance. It also highlights the dynamic nature of basic neuronal properties in adult cortex since repeated adaptations modified both the orientation tuning selectivity and the response strength to the preferred orientation. These enhanced neuronal responses suggest that the range of neuronal plasticity available to the visual system is broader than anticipated.     

Functional characteristics of visual cortical neurons during local photic stimulation of their receptive fields in cats

A group of functional characteristics of 103 neurons in visual cortical area 17 was investigated in acute experiments on curarized, light-adapted cats during a change in various parameters of the local photic stimuli. The average threshold sensitivity of the neuron population was 32 dB (0.052 nit), the sharpness of orientation tuning was 37°, the critical summation time was 57 msec, and the reactivity recovery time 190 msec. Photic sensitivity was lower during light adaptation than during dark adaptation, orientation selectivity of the neurons was increased, temporal summation was lengthened, and the time required by the neuron to recovery from after-inhibition was shortened. Several properties of the cortical neurons depended on the accentricity of their receptive fields: Cells with centrally localized receptive fields on average had lower thresholds and shorter summation time and they recovered their reactivity more quickly; their activity was of a higher frequency and they more often generated short phasic discharges than neurons with receptive fields in the peripheral part of the visual field. The mechanisms responsible for changes in the properties of neurons in the central and peripheral visual channels during dark and light adaptation are discussed. The presence of several inhibitory subsystems in the cortex regulating unit activity in the primary visual projection area is postulated.     

Double orientation tuning of neurons in the primary cortex of cat at different levels of alertness

Orientation tuning (OT) of 225 cat neurons of the primary visual cortex (field 17) to the flashing of a light bar in the discharge centers of their receptive field (RFs) were investigated. It was found that 43% of the cells investigated were monomodally tuned, i.e., were primarily detecting horizontal and vertical orientations. The remaining 57% of the neurons exhibited double OT, i.e, exhibited, in addition to a main preferred orientation (PO), an additional preferred orientation (aPO) at a right or acute angle to the main orientation (the mean angle between the two OT maxima equalled 71.4±2.4°). In bimodal cells, the additional maximum of OT was comparable in magnitude to the main maximum (averaging 0.7±0.03 of the PO) in half the cases. The orientational properties of the main and additional maxima were almost indistinguishable. Under light or moderate anesthesia, approximately half the neurons with double OT became monomodal; at the same time, a small fraction of monomodal cells (12%) manifested double OT. Under anesthesia, the angle between two the preferred orientations decreased, while the ratio of amplitude characteristics remained unchanged. Monomodal neurons frequently exhibited simple RFs and OTs unaffected by anesthesia. Neurons with double OT, on the other hand, exhibited simple and complex types of RFs just as often and their OT changed under the influence of anesthesia. It is suggested that neurons with double OT can function as detectors of angles and angles of intersecting lines; such angles, together with line orientation, are important attributes of images. In contrast, monomodal neurons may provide a benchmark for a stable reference system of orientation coordinates. The interaction of the two neuronal systems mentioned may allow effective analysis of image attributes at the level of the primary visual cortex.Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences Moscow. Translated from Neirofiziologiya, Vol. 24, No. 3, pp. 260–269, May–June, 1992.     

Dynamics of tuning to orientation of cross-like figures in neurons from the cat visual cortex

Dynamics of tuning to orientation of flashing light bar and to orientation of cross-like figure was studied by a temporal slices method in 87 neurons of the cat primary visual cortex. Tuning was plotted by spikes number in the entire response and in its successive fragments with a step of 20 ms. It was found that successive dynamic shift of preferred orientation of a bar was typical for 87% units, white such shift of preferred orientation of a cross was met in 75% of cases. Comparison of tuning dynamics for bar and cross allowed to separate units into three groups: the first one (58.6% of cases) with larger dynamic shift of a bar preferred orientation then of a cross (74.9 +/- 5.8 degrees [symbol: see text] 29.8 +/- 4.1 degrees, correspondingly, p < 0.00001), the second group (21.5%) with opposite effect (24.2 +/- 5.2 degrees and 69.2 +/- 10.0 degrees, p < 0.0002) and the third group (19.8%) without significant shift of preferred orientation of bar and cross and without difference in their dynamics. Possible mechanisms of the preferred orientation dynamics and its difference for bar and cross are discussed.     

Dynamic modification of cortical orientation tuning mediated by recurrent connections

Receptive field properties of visual cortical neurons depend on the spatiotemporal context within which the stimuli are presented. We have examined the temporal context dependence of cortical orientation tuning using dynamic visual stimuli with rapidly changing orientations. We found that tuning to the orientation of the test stimulus depended on a briefly presented preceding stimulus, with the preferred orientation shifting away from the preceding orientation. Analyses of the spatial-phase dependence of the shift showed that the effect cannot be explained by purely feedforward mechanisms, but can be accounted for by activity-dependent changes in the recurrent interactions between different orientation columns. Thus, short-term plasticity of the intracortical circuit can mediate dynamic modification of orientation tuning, which may be important for efficient visual coding.     

Dynamics of orientational tuning of feling visual cortex neurons under the effects of sombrevine

Dynamics of orientational tuning in 59 primary visual cortex neurons were investigated before and after sombrevine-induced anesthesia during acute experiments on immobilized cats using temporal slice techniques. A dynamic shift in preferred orientation of a flashing light strip, during which peak amplitude of spike discharges was noted (at an angle of between 22 and 157°) occurred as response developed in two-thirds of the cells. We had previously named this effect "scanning the orientational range" [9]. Scanning declined significantly in 45% of the sample, culminating in complete disappearance of this effect in some cells following sombrevine action. Scanning intensified in 30%, while dynamics of tuning remained unchanged in 25% of units. Sombrevine administration induced change in the preferred stimulus orientation of 60% of the neurons (referred to as "unstable" cells) and remained constant in "stable" cells (= 40%). Dynamic changes in preferred stimulus orientation were 2.5 times as high as those of stable cells in the waking state. The scanning effect declined significantly in 60% of "unstable" neurons under the action of anesthesia and remained unchanged in not more than 6%. At the same time, orientational tuning did not alter in the "stable" cell group in 46% of units, either declining (25%) or increasing (29%) in the remaining scanning ranges.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 1, pp. 107–113, January–February, 1990.     

Orientation sensitive properties of visually driven neurons in extrastriate area 21a of cat cortex

Orientation sensitive properties of extrastriate area 21a neurons were investigated. Special attention was paid to the qualitative characteristics of neuron responses to the different orientations of visual stimulus motion across neuron classical receptive fields (CRF). The results of experiments have shown that a group of neurons (31%) in area 21a with specialized responses to moving visual stimuli changed their direction selective (DS) characteristics depending on the orientation of the stimulus movement. Some neurons reveal an abrupt drop of the direction sensitivity index (DI) to certain orientation (58%), and some show significant increase of DI at one of applied orientations of stimulus motion (22%). Detailed investigation of response patterns of non-directional neurons to different orientations of stimulus motion have revealed clear-cut qualitative differences, such as different regularities in the distribution of inter-peak inhibitory intervals in the response pattern in dependence of the orientation of stimulus motion. The investigation of neuron CRF stationary functional organization did not reveal correlations between RF's spatial functional organization, and that of qualitative modulations of neuron response patterns. A suggestion was put forward, that visual information central processing of orientation discrimination is a complex integrative process that includes quantitative as well as qualitative transformations of neuron activity.