Characteristic properties of spontaneous discharges synchronized with heart beat in thalamic ventrobasal complex / 全日本鍼灸学会雑誌

ABSTRACT

A total of 681 unitary activities were recorded extracellularly in the thalamic ventrobasal complex (VB) of anesthetized and immobilized cats, of which 67 units were synchronized with heart beat (HB) with some relative latency. HB discharges were divided into six types according to the shape in their post Rwave time histogram (PRTH) analysis, however some HB changed in both the number and relative latency of the discharge, and were identified their receptive fields (Rfs) on or in the bodies, of 35 units of the 681 (5.1%). These HB Rfs were distributed widely from the tip of auricula to the toe of hindlimb. The lateralities of their HB Rfs were all contralateral to recording sites in the thalamic VB. In general, the HB Rfs of the thalamic VB were distributed on upper half of the bodies much more than the lower half; especially on the upper cervix, the chest and the forelimbs. The somatotopic organization of HB units in thalamic VB showed the same tendency. The relative latencies between the R-wave of ECG and HB activities showed the tendency to be dependent on the distances from the Rfs to the recording sites in thalamic VB. Some HB activity was followed by a silent period when the background activities disappeared during several tens of milliseconds which was presumably caused by a feedback inhibitory mechanism consisting of the axon collateral of the thalamocortical cell and the inhibitory interneuron.