Neural mechanisms underlying human cognitive control and working memory

Abstract

Cognitive control involves flexibly combining multiple sensory inputs with task-dependent goals during decision making. Several tasks involving distinct sensory inputs and motor outputs have been proposed to examine cognitive control, including the Stroop, the Eriksen-flanker, and the multi-source interference task. It remains unclear whether neural signals during cognitive control extrapolate across different conditions within each task. Furthermore, because these tasks have mostly been studied independently, it remains elusive whether the neural signatures of cognitive control reflect an abstract control mechanism or specific combinations of sensory and behavioral aspects of each task. To address these questions, we recorded invasive neurophysiological signals from 16 subjects and directly compared neural responses within and across tasks. Neural activity patterns in the theta (4-8 Hz) and high-gamma (70-120 Hz) frequency bands differed between incongruent and congruent conditions, revealing strong modulation by conflict. These neural signals were specific to each task, generalizing within a task but not across tasks. These results highlight the complex interplay between sensory inputs, motor outputs, and task demands underlying cognitive control processes. Working memory is an essential cognitive function that is important for every aspect of life. In this study we implemented a well-known memory matching game to investigate complex human working memory behaviors under rich contexts. Subjects were initially presented with covered images on a board and were instructed to reveal any two images each time, until all matching pairs of images were located. We recorded intracranial field potentials from 20 pharmacologically-intractable epilepsy patients while they were playing the game. Leveraging generalized linear models to assess the relative contribution of multiple parameters on the neural responses simultaneously, we found that neural activities in the gamma band (30-150 Hz) captured a wide array of working memory status including novelty, familiarity, or recency. The ability to represent the recency of pair existed only during successful associative recall, which was forecasted by distinctive gamma responses.