To determine how task goals dynamically modulate sensory representations in the human ventral temporal cortex (VTC) and identify the cortical mechanisms supporting such flexible reorganization.
While VTC has traditionally been viewed as encoding stable visual category representations, animal studies have shown that sensory cortices can be modulated by top-down contextual signals. How dynamic modulation is implemented within the human sensory cortex to support cognitive flexibility and how higher-order regions such as dorsal anterior cingulate cortex (dACC) coordinate this process, remain unknown.
We recorded activity from 773 single neurons and local field potentials (LFPs) across six brain regions, including VTC and dACC, in 11 patients with medically refractory epilepsy undergoing intracranial monitoring. Participants performed a flexible visual decision-making task where identical stimuli were presented either with or without task goals, allowing sensory input to be dissociated from contextual information. Neural selectivity and inter-areal dynamics were characterized using a combination of statistical, decoding, and spike-field coherence analyses.
VTC neurons showed robust category selectivity, and a subgroup of the neurons exhibited mixed selectivity for both category and task goals. Population activity in VTC during the stimulus window reliably distinguished the presence of task goals, with sharpened category representations when goals were specified in advance. dACC and hippocampus carried stronger contextual signals compared to VTC, consistent with a hierarchical gradient of top-down control. dACC-VTC coherence increased under uncertainty (when task goals not given early) and higher cognitive demand (complex task goals), particularly in beta (12-32 Hz) and theta (4-7 Hz) frequency bands, and coupling strength predicted correct task performance.
These findings reveal that human sensory codes are not fixed but dynamically reshaped by medial frontal (dACC) modulation, offering potential therapeutic targets for cognitive dysfunction following acute brain injury, such as post-stroke cognitive impairment.