Subcortical correlates of the somatic, auditory and visual vertex activities. II. Referential EEG responses.

A systematic analysis of polarity, amplitude and latency of the referential EEG responses correlated to surface somatic (SVA), auditory (AVA) and visual (VVA) vertex activities (VA) was done in various subcortical structures of a non-specific system of the same group of patients with electrodes implanted and reported in a previous work. These structures included the caudal and rostral mesencephalic reticular formations (cttc and rttc), the subthalamic region (Sth), the centro-median (Ce), parafascicular (Pf), ventrolateral (VL), dorsolateral (DL) and reticularis (Rt) thalamic nuclei; the orbito-frontal cortex (GO), the anterior commissure (Acm), the pallidum medialis and lateralis (Pm and Pl), the putamen (Pt) and the amygdala (Am). Subcortical SVA, AVA and VVA were formed by 4 consecutive components O, A, B and C correlated to components P1, N1, P2 and N2 of the surface VA. Components A and B of the subcortical SVA reversed polarity 4 times when recorded in structures arranged in a caudo-rostral order: between rttc-Ce and VL, between Rt and GO, between GO and Acm and between Acm and Am. Components A and B of subcortical AVA and VVA reversed polarity two times each: AVA between cttc and rttc and between GO and Acm; while VVA between GO and Acm and between Acm and Pm. Components A and B of SVA and VVA attained maximal amplitudes and minimal latencies at GO. From here, their amplitude decreased and latency increased with distance along other structures rostrally and caudally located. Components A and B of AVA attained maximal amplitudes and minimal latencies at cttc.(ABSTRACT TRUNCATED AT 250 WORDS)