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  • 1965-1969  (2)
  • Computer simulation  (1)
  • Inhibition  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Functional synaptic organization of primary visual cortex neurones in the cat (1968)
    Springer
    Experimental brain research 6 (1968), S. 324-352 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Intracellular recording ; Receptive fields ; Computer simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spontaneous and light evoked post-synaptic activity of cells of the primary visual cortex was investigated with intracellular and quasi-intracellular records. The resting membrane potential fluctuated mostly between 3–10 mV below the firing threshold owing to spontaneous EPSP- and IPSP-activity. Discharge activity was therefore low. Forms and amplitudes of the visible EPSP's showed a large variability, the frequency was 150–300/sec. Discrete IPSP's were between 0.5–3 mV and were less frequent than EPSP's (about 1∶10). Their duration was only slightly longer than that of EPSP's. EPSP's and IPSP's could be elicited at on or off by appropriately positioned small light stimuli. During the initial reaction following a stimulus, single PSP's could be distinguished. Geniculate on-center- as well as off-center-afferents could lead to excitation or inhibition in different neurones. The receptive fields of cortical cells to monocular stimulation were analysed with averaged records. In each neurone 2–4 overlapping areas of on- or off-activation or -inhibition could be distinguished. Each of these activation or inhibition zones had the functional properties of a single geniculo-cortical onor off-center fibre with their receptive field centers separated by 1–3°. The variety of functional organizations of the cortical neurones to monocular stimulation was explained by variable combinations of 2–4 converging geniculate on- or off-center fibres with either excitatory or inhibitory action and variable overlap of their receptive fields. This was tested in a simple computer model. — Most neurones with pronounced reactions to movement or with direction specific movement sensitivity (about half of the neurones investigated) had an excitatory contact with an off-center fibre, which seemed to be mainly responsible for the movement reaction.- The findings suggest that from each eye less than 5 geniculo-cortical afferent converging fibres have a major effect on the activity of one cortical cell. Inhibitory afferents may be indirect and relayed through another cortical pyramidal cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233183
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The origin of cerebellar-induced inhibition of Deiters neurones II. Temporal correlation between the trans-synaptic activation of Purkinje cells and the inhibition of Deiters neurones (1966)
    Springer
    Experimental brain research 2 (1966), S. 350-364 
    Details
    ISSN: 1432-1106
    Keywords: Deiters neurones ; Inhibition ; Climbing fibre responses ; Inferior olive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracellular recording with microelectrodes has been employed to reveal the causal relationship between the trans-synaptic activation of cerebellar Purkinje cells and the postsynaptic inhibition of Deiters neurones. Cerebellar stimulation produced in Deiters neurones not only monosynaptic IPSPs with latency of 0.9–1.5 msec, but also the delayed IPSPs at 1.5–9 msec. Correspondng to the latter, Purkinje cells were found to be activated orthodromically with the characteristic climbing fibre responses (CFRs), the latency varying from 0.8 up to 10 msec. On the other hand, stimulation of the inferior olive first induced EPSPs in Deiters neurones, presumably monosynaptically, then with a short delay of less than a millisecond CRFs in Purkinje cells of the anterior lobe, which in turn were succeeded by IPSPs in Deiters neurones after a further delay of a millisecond. Spinal stimulation activated the inferior olive trans-synaptically and thereby produced CFRs in Purkinje cells and a sequence of EPSPs and IPSPs in Deiters neurones. Close correlation between these spinal-induced events in both neurone species was further indicated by the concurrence of their fluctuations in intensity, these fluctuations being characteristic of the spino-olivary transmission mechanism. These results strongly support the postulate that the cerebellar Purkinje cells are inhibitory in their action upon Deiters neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234780
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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