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  • 1
    Electronic Resource
    Electronic Resource
    Neuronal responses in the visual cortex of awake cats to stationary and moving targets (1971)
    Springer
    Experimental brain research 12 (1971), S. 389-405 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Unanesthetized and unparalyzed cats ; Neuronal responses to moving and stationary stimuli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Over 300 single units from the visual cortex (within and around the projection of the central area) were recorded from awake and non-paralyzed cats (chronic preparation). Spontaneous activity of 25% of the neurons was below 3/sec, that of 75% above 3/sec (mean 7.65 spikes/sec). Diffuse illumination had only little influence, but nearly all neurons responded to stimulation with some sort of visual contrast. This would be either an irregularly moved shadow on the screen with irregular boundaries (e. g. a hand with moving fingers), a dark stripe moving in a certain direction, stationary parallel gratings with a certain orientation, or saccadic eye movements across a checkerboard. Although some neurons responding to one stimulus type could also be responsive to other stimuli, the majority of units only responded to one stimulus type. The responses to stationary gratings (alternating parallel dark and bright stripes) and to moving dark stripes are described in detail. Responses to stationary gratings showed no adaptation. The orientation of the grating stripes was critical for each neuron, the optimal and minimal response orientation were separated by about 90°. For movement sensitive neurons, the direction of the movement was critical. Most neurons had only one, some had two preferred directions separated by 180°. No statistically significant predominance of certain orientation or direction preferences was found. The preferred target velocity of movement sensitive neurons was between 10 and 60°/sec, above 80–100°/sec only occasional or no responses could be elicited. Neurons which responded to saccadic eye movements (above 300°/sec) in the presence of a checker board, usually did not respond to slower target movements below 100°/sec. The results support the view that the visual system has different channels for the perception of moving and of stationary objects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234494
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Binocular interaction in the visual cortex of awake cats (1971)
    Springer
    Experimental brain research 12 (1971), S. 406-421 
    Details
    ISSN: 1432-1106
    Keywords: Single units ; Visual cortex ; Binocular interaction ; Awake and unparalyzed cats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of monocular and binocular stimulation on cortical neurons of area 17 was investigated in awake unparalyzed cats with painless head fixation. Two types of stimuli were applied: Stationary gratings of variable orientations, and a 3° wide dark stripe at different orientation and moving in different directions. All neurons which were excited from both eyes showed qualitatively similar input properties (orientation specificity, movement and/or direction sensitivity). Quantitatively, the input from both eyes was either equal or dominant from one eye. Contralateral dominance was found 5 times more frequently than ipsilateral dominance. Various types of binocular interaction were found. Some neurons showed an excitatory response from one eye and inhibitory response from the other (inhibition, 14% of our units), and others showed a response during binocular stimulation which was equal to the sum of the monocular responses (summation, 18%), larger (facilitation, 43%) or smaller (occlusion, 14%) than the sum of the two monocular responses. A few units with binocular responses did not respond to monocular stimulation of one or both eyes. The results are compared with those found by other authors in paralyzed and anesthetized animals, and current theories of neuronal mechanisms of binocular vision are discussed in the context of our findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234495
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    An intracellular analysis of visual cortical neurones to moving stimuli: Responses in a co-operative neuronal network (1974)
    Springer
    Experimental brain research 21 (1974), S. 251-274 
    Details
    ISSN: 1432-1106
    Keywords: Area 17 ; Orientation/direction sensitivity ; Intracellular recording ; Receptive field properties ; Intracortical inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Responses of cortical cells from the foveal and perifoveal visual field representation in area 17 to moving contrasts were analyzed with intracellular records in anesthetized cats. These intracellularly recorded responses were normal in so far as the cells showed typical orientation/direction sensitivity and only short phasic or no responses to diffuse illumination. 2. With slowly moving bright or dark bars, two types of responses were seen: those with a small excitatory peak and those with a wider excitatory peak. Inhibitory regions outside the excitatory peak were only seen in cells with a small excitatory area. Only very few cells showed inhibitory “flanks” preceding and following the excitation; often inhibition followed the excitation in both the forward and backward direction; sometimes it preceded it in both directions. The inhibition outside the excitatory zone practically always had “dynamic” properties, i.e. was smaller or larger in the two opposite directions of movements. 3. All cells showed strong inhibition (IPSP's) mixed with excitation while the stimulus moved over the excitatory response field. The degree of inhibition was clearly sensitive to the direction of movement (forward or backward) of an optimally oriented moving stimulus, and could also be different at different orientation/ directions. However, the orientation dependence of intracortical inhibition was often less clear than the differences found between the two opposite directions of an optimally oriented stimulus. Inhibition was more marked during binocular than during monocular stimulation. 4. The excitatory areas of cortical cells were mostly slightly elongated, but not systematically along the axis of optimal orientation. The diameters of the excitatory fields were similar along the optimal and the non-optimal orientation axes (mean 1.9±0.78 vs. 2.2±0.92°). 5. It is proposed that the orientation/direction sensitivity of cortical cells is a function of intracortical inhibitory connections with direction/orientation sensitivity rather than only due to the spatial arrangement of excitatory and inhibitory on- or off-center fields. A hypothetical retino-cortical projection map is proposed and it is assumed that direction/orientation sensitive intracortical inhibition is essential for the functional properties of cortical neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235746
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Reciprocal lateral inhibition of on- and off-center neurones in the lateral geniculate body of the cat (1970)
    Springer
    Experimental brain research 10 (1970), S. 311-330 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate body ; Inhibitory interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the lateral geniculate body (LGB), intra- and quasi-intracellular records were done. With small light stimuli shone into different parts of the receptive field, EPSPs and IPSPs could be elicited. Stimulation of the exact center of an on-center cell produced a pure excitatory response, that of an off-center neurone pure inhibition. This response lasted throughout the stimulus. At light off, inhibition was elicited in on-center cells and excitation in off-center cells. A stimulus in the field periphery produced a mixed response with a small and short excitation followed by large inhibition in on-center cells, and a short inhibition followed by postsynaptic depolarization in off-center cells. At light off, on-center cells showed depolarization after a short polarizing phase, and off-center cells a broad polarization which interrupted the initial small excitation. The latencies of both the excitatory and inhibitory center responses at light on and off characteristic for the two types of neurones, were 20–30 msec shorter than the reversed responses elicited by stimulation of the receptive field surround. The findings are compatible with a model in which each geniculate on-center cell gets its major excitatory input from one optic tract on-center fibre and inhibitory input from several off-center fibres with nearby receptive fields. An off-center LGB-cell receives its main excitation essentially from one offcenter fibre and inhibition from several on-center cells. The responses to moving stimuli also agreed with this model. The presence of recurrent inhibition within the LGB could be confirmed by electrical stimulation. But it could not be decided whether the reciprocal inhibition of on- and off-center cells was due to forward or backward inhibition. The spontaneous activity of on- and off-center cells which were simultaneously recorded with one electrode, showed a mutual inhibition 6–8 msec after one cell had fired. Anatomical data relevant to the model are discussed and some functional implications are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235054
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    Paper (German National Licenses)
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