Figure 3: Simultaneous recording with a broad coverage for tracking the spatiotemporal profiles of activity of populations of neurons during a particular cognitive task.

In a group of subjects simultaneous recordings in the lateral parietal and inferior temporal regions tracked HFB responses in each electrode site while the subjects were making true/false judgments on an arithmetic task in which operands (numerals 1–9) and operators (+. =) were visually presented one symbol at a time (e.g. “2”, “+”, “2”, “=”, “4”). Non-selective HFB responses in lateral occipital gyrus (LOG) and medial fusiform gyrus (mFG) contrasted the selective HFB responses to numerals in the posterior inferior temporal gyrus (pITG, red) and anterior intraparietal sulcus region (aIPS, upper left panel). Note the stronger responses in the pITG and aIPS after the presentation of the second numeral following the “+” sign and the opposite profile of HFB responses in the LOG and mFG sites. Also, of interest was the finding of HFB response selectivity across the three adjacent pITG sites (left lower panel). Neuronal populations that are ~5mm apart show clearly different profiles of responses. Note the most selective responses to numbers in the number form area (NFA) that has previously been reported in a different set of subjects¹⁰⁰. Adapted from Daitch et al 2016.