Postsynaptische Potentiale von Nervenzellen des motorischen Cortex nach elektrischer Reizung spezifischer und unspezifischer Thalamuskerne

  • A. C. Nacimiento
  • H. D. Lux
  • O. D. Creutzfeldt


1. Postsynaptic potentials (PSP) of motor cortex nerve cells after electrical stimulation of specific (VL and VPL) and non-specific (CM, reuniens, VA) thalamic nuclei were investigated with intracellular microelectrodes. After VL-stimulation compound PSPs with primary fast and secondary slow EPSP and subsequent IPSP were found in all pyramidal tract cells and many unidentified cells mostly located in deep cortical layers. Cells with primary IPSP were mainly found in superficial layers (down to 600 μ). After CM-stimulation long EPSPs were recorded from the same cells which showed compound VL-PSPs.

2. The different components of compound VL-PSPs showed different behaviour regarding stimulus strength and frequency. With weak single stimuli the secondary EPSP was more prominent whereas after strong stimuli only the primary EPSP and the IPSP could be identified. The secondary EPSP was cut off by the IPSP and could be recognized only as a notch on its rising phase. With increasing frequency the secondary EPSP became more prominent whereas the IPSP disappears at frequencies above 5–8/sec.

3. The mean time constant (± S.E.) of decay of compound VL-EPSP's at 8/sec was 10.5 ± 1.0 msec thus being slightly above the neuron time constant of 8.5 ± 0.7 msec, the decay time constant of CM-EPSP's was 14.0 ± 1.1 msec and that of VL-IPSP's 56.1 ± 7.8 msec.

4. The current underlying different PSPs showed only little or no residual current in VL-EPSPs, but long lasting delayed currents during CM-EPSPs and VL-IPSPs.

5. Comparison between PSPs and evoked potentials showed a close relationship between surface negative waves and both the secondary VL-EPSP and the CM-EPSP, especially during recruiting and augmenting responses.

6. The differences between specific and non-specific PSPs were interpreted as being due to topographic differences of the corresponding synaptic inputs. On the basis of findings reported here and in a different communication (Creutzfeldt and Lux 1964) it was suggested that non-specific afferents have axodendritic synaptic contacts much more distant from the soma than specific afferents.


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Copyright information

© Springer-Verlag 1964

Authors and Affiliations

  • A. C. Nacimiento
    • 1
  • H. D. Lux
    • 1
  • O. D. Creutzfeldt
    • 1
  1. 1.Aus der Abteilung für Experimentelle Neurophysiologie der Deutschen Forschungsanstalt für Psychiatrie (Max Planck-Institut)München

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