Position and organization of thalamic cellular activity during diencephalic recording. II. Joint- and muscle-evoked...

With the aid of a computer graphic display technique, data gathered from exploratory diencephalic recordings in 130 stereotactic operative procedures are presented to show the differing topographical distribution of 'joint'- and 'muscle'-evoked cellular activity. In addition, the variable position of these responses in relation to common diencephalic landmarks is presented. Our findings indicate that response points lie in a sickle-shaped zone 14-19 mm lateral to the midline and 2-11 mm posterior to the midcommissural plane. This area correlates closely with the findings of others on the thalamic zone of 1A afferent projections and agrees with the anatomical position of the nucleus ventralis intermedius as plotted by others. When the response points are plotted against a common posterior commissure, a more compact grouping is obtained and 'muscle'- and 'joint'-evoked responses are noted to separate into different zones, with 'muscle' responses positioned slightly anterior and inferior to those for 'joint'. Somatotopographically, face responses were positioned posteriomedially and leg responses anterolaterally.