Supranormal orientation selectivity of visual neurons in orientation-restricted animals. (original) (raw)
Related papers
Orientation selectivity without orientation maps in visual cortex of a highly visual mammal
2005
In mammalian neocortex, the orderly arrangement of columns of neurons is thought to be a fundamental organizing principle. In primary visual cortex (V1), neurons respond preferentially to bars of a particular orientation, and, in many mammals, these orientationselective cells are arranged in a semiregular, smoothly varying map across the cortical surface. Curiously, orientation maps have not been found in rodents or lagomorphs. To explore whether this lack of organization in previously studied rodents could be attributable to low visual acuity, poorly differentiated visual brain areas, or small absolute V1 size, we examined V1 organization of a larger, highly visual rodent, the gray squirrel. Using intrinsic signal optical imaging and single-cell recordings, we found no evidence of an orientation map, suggesting that formation of orientation maps depends on mechanisms not found in rodents. We did find robust orientation tuning of single cells, and this tuning was invariant to stimulus contrast. Therefore, it seems unlikely that orientation maps are important for orientation tuning or its contrast invariance in V1. In vertical electrode penetrations, we found little evidence for columnar organization of orientation-selective neurons and little evidence for local anisotropy of orientation preferences. We conclude that an orderly and columnar arrangement of functional response properties is not a universal characteristic of cortical architecture.
The nature and origin of orientation specificity in neurons of the visual pathways
Progress in Neurobiology, 1994
Orientation specificity and the receptive field 382 l l A defimUon 382 1 2 Orientation specificity with moving stimuli 382 l 3 Orientation specificity with moving or stationary bars 382 1 4 Onentatlonal and &rectlonal response components 384 Orientation specificity in different cell types 386 2 l The simple or S cell 386 2 l 1 Receptive field topography 386 2 1 2 Shape of the orientation tuning curve 2 2. The complex or C cell 388 2 2 1. Receptive field topography 388 2.2 2 Shape of the orientation tuning curve 388 2 3 The hypercomplex or H property 2.3 1 RecepUve field topography 2.3 2 Shape of the orientation tunmg curve Models for onentaUon specificity 3 1 Models based on neural connections 31.1 ForScells 3 1 1 1. Convergence of excitatory inputs from the dLGN 3 1 1 2. A single excitatory input from the dLGN 3 1.1 3 The contribution of cortical mhtbmon 3 1 1.4. The relationship of excitatory and inhibitory regions 3 1 2 The formation of columns in S cell models 3 1 2.1 Models with convergence of excitatory inputs 401 3 1 2 2 Models with cortical inhibition 401 3.1.2.3 Models with overlapping regions 3 1.3 For C cells 3.1 3 1 Convergence of excitatory Inputs from S cells 3 1 3 2 Convergence of Inputs from the dLGN 3 1 3.3. The influence of cells with orientation bias 3 1 3 4 The organasatlon of dual inputs 3 2 Models based on neural development 3 2 1 Theoretical and experimental foundations 3 2 1.1 Presumptive rules for neural development 3 2 1.2. Orientation specificity in newborn, visually naive ammals 3 2 1.3 Orientation specificity in ammals deprived of patterned vision 3 2 2 Models lacking retinotoplc orgamsauon 3.2 2.1 A basic design 3 2 2.2. Developmental schemes to modify the strength of ascending connecUons 3.2 2 3 Evaluation of models lacking retmotopic orgamsatlon 3 2 3 Models with retinotoplc orgamsatlon 3 2 3 1 Featuring a multllayered neural network 3 2 3 2 Featuring parallel ON-and OFF-centre inputs 3 2 3 3 Featuring a reverse-Hebb rule of synapttc development
We used the intrinsic signal optical imaging technique to assess the effect of orientation-restricted visual experience on response properties of the rat visual cortex. We placed young animals wearing goggles fitted with plano-convex cylindrical lenses in a stimulus-enriched environment for 3 weeks. Experienced orientation was over-represented in the visual cortex, which was associated with the under-representation of orthogonal orientation. These findings suggest that chronic exposure to a single orientation can modify orientation preferences even in rats lacking in orderly arrangement of preferred orientations. #
Long adaptation reveals mostly attractive shifts of orientation tuning in cat primary visual cortex
Neuroscience, 2009
In the adult brain, sensory cortical neurons undergo transient changes of their response properties following prolonged exposure to an appropriate stimulus (adaptation). In cat V1, orientation-selective cells shift their preferred orientation after being adapted to a non-preferred orientation. There are conflicting reports as to the direction of those shifts, towards (attractive) or away (repulsive) from the adapter. Moreover, the mechanisms underlying attractive shifts remain unexplained. In the present investigation we show that attractive shifts are the most frequent outcome of a 12 min adaptation. Overall, cells displaying selectivity for oblique orientations exhibit significantly larger shifts than cells tuned to cardinal orientations. In addition, cells selective to cardinal orientations had larger shift amplitudes when the absolute difference between the original preferred orientation and the adapting orientation increased. Conversely, cells tuned to oblique orientations exhibited larger shift amplitudes when this absolute orientation difference was narrower. Hence, neurons tuned to oblique contours appear to show more plasticity in response to small perturbations. Two different mechanisms appear to produce attractive and repulsive orientation shifts. Attractive shifts result from concurrent response depression on the non-adapted flank and selective response facilitation on the adapted flank of the orientation tuning curve. In contrast, repulsive shifts are caused solely by response depression on the adapted flank. We suggest that an early mechanism leads to repulsive shifts while attractive shifts engage a subsequent late facilitation. A potential role for attractive shifts may be improved stimulus discrimination around the adapting orientation.
1982
The development of stimulus selectivity in the primary sensory cortex of higher vertebrates is considered in a general mathematical framework. A synaptic evolution scheme of a new kind is proposed in which incoming patterns rather than converging afferents compete. The change in the efficacy of a given synapse depends not only on instantaneous pre-and postsynaptic activities but also on a slowly varying time-averaged value of the postsynaptic activity. Assuming an appropriate nonlinear form for this dependence, development of selectivity is obtained under quite general conditions on the sensory environment. One does not require nonlinearity of the neuron's integrative power nor does one need to assume any particular form for intracortical circuitry. This is first illustrated in simple cases, e.g., when the environment consists of only two different stimuli presented alternately in a random manner. The following formal statement then holds: the state of the system converges with probability 1 to points of maximum selectivity in the state space. We next consider the problem of early development of orientation selectivity and binocular interaction in primary visual cortex. Giving the environment an appropriate form, we obtain orientation tuning curves and ocular dominance comparable to what is observed in normally reared adult cats or monkeys. Simulations with binocular input and various types of normal or altered environments show good agreement with the relevant experimental data. Experiments are suggested that could test our theory further.
World Scientific Series in 20th Century Physics, 1995
The development of stimulus selectivity in the primary sensory cortex of higher vertebrates is considered in a general mathematical framework. A synaptic evolution scheme of a new kind is proposed in which incoming patterns rather than converging afferents compete. The change in the efficacy of a given synapse depends not only on instantaneous pre-and postsynaptic activities but also on a slowly varying time-averaged value of the postsynaptic activity. Assuming an appropriate nonlinear form for this dependence, development of selectivity is obtained under quite general conditions on the sensory environment. One does not require nonlinearity of the neuron's integrative power nor does one need to assume any particular form for intracortical circuitry. This is first illustrated in simple cases, e.g., when the environment consists of only two different stimuli presented alternately in a random manner. The following formal statement then holds: the state of the system converges with probability 1 to points of maximum selectivity in the state space. We next consider the problem of early development of orientation selectivity and binocular interaction in primary visual cortex. Giving the environment an appropriate form, we obtain orientation tuning curves and ocular dominance comparable to what is observed in normally reared adult cats or monkeys. Simulations with binocular input and various types of normal or altered environments show good agreement with the relevant experimental data. Experiments are suggested that could test our theory further.
Adaptation-Induced Plasticity of Orientation Tuning in Adult Visual Cortex
Neuron, 2000
changes induced by temporal context. Therefore, we examined here the plasticity of orientation tuning, using Cambridge, Massachusetts 02139 pattern adaptation (Movshon and as the induction procedure, by analyzing how the entire profile of the orientation tuning curve changes after short-and long-Summary term adaptation to a particular stimulus orientation. A key emergent property of the primary visual cortex (V1) is the orientation selectivity of its neurons. The extent to which adult visual cortical neurons can ex-Results hibit changes in orientation selectivity is unknown.