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  • 1970-1974  (2)
  • Inhibitory interaction  (1)
  • Orientation/direction sensitivity  (1)
  • 1
    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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  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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