ISSN:
1573-899X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. Intracellular postsynaptic potentials (PSPs) generated in 67 neurons of the anterior and posterior sigmoid gyri of the cat were investigated under chloralose anesthesia (60–80 mg/kg) in response to presentation of somesthetic, photic and acoustic stimuli. 2. In each neuron, in response to all stimuli tested, PSPs of fairly similar shape and with similar properties were recorded. 3. In most neurons the response consisted of a primary EPSP, followed by a long (100–500 msec) IPSP. The primary EPSPs had a duration of 5–50 msec and they usually led to generation of 1–10 spikes. In three cells somesthetic stimulation evoked spike discharges, while photic and acoustic stimulation evoked only subthreshold EPSPs. The IPSP effectively inhibited spontaneous activity and “injury” discharges, while if KCl electrodes were used, it was converted into a depolarizing potential. The latent periods of the responses to electrodermal stimulation of the contralateral rorelimb varied for different neurons between 9 and 32 msec (mean 18 msec), to stimulation of the ipsilateral hindlimb they varied from 13 to 30 msec (mean 22 msec), to clicks from 10 to 65 msec (mean 21 msec), and to flashes from 12 to 50 msec (mean 31 msec). A valid correlation was found between the values of the latent periods for different stimuli. 4. On passing a current through the intracellular microelectrode, regular changes were observed in the PSPs, identical for responses to all stimuli. During hyperpolarization of the membrane the EPSPs increased in amplitude, while during depolarization they decreased, and with currents of 2−4×10−9a, they changed their sign. The IPSPs behaved in the opposite manner. 5. The results obtained are regarded as confirmation of the view that primary convergence of stimuli of different modalities for the motor cortex does not occur to any great degree at the cortical neuron. It is postulated that these stimuli enter the cortex along pathways basically similar in their organization, or even along the same pathways, forming powerful synaptic connections terminating near the cell bodies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01125919
