Figure 4. Recording sites in the inferior frontal lobe of both monkeys.

(A) Lateral view of the left hemisphere indicating the recording area: parts of the rostroventral premotor cortex (PMrv of area 6), the fundus of the inferior arcuate sulcus (ASi) encompassing area 44, and the ventral pre-arcuate region containing parts of area 45. The inferior arcuate sulcus is unfolded, with dotted lines marking the transition from the cortical surface to the gyral walls. PS, principal sulcus; ASi, inferior arcuate sulcus; ASs, superior arcuate sulcus (B, C) Precise recording sites inside each recording chamber (dotted circles). Recording sites with a depth >6 mm were defined as ASi sites. For better overview, recording sites within the fundus of the inferior AS (area 44) are depicted offset on the right side of each chamber. The proportion of vocalization-correlated neurons (B) in relation to all neurons recorded at a specific recording site is coded with different shades of blue. Similarly, the proportion of hand-correlated neurons (C) in relation to all neurons recorded at a specific recording site is coded with different shades of green color.