Face neurons in human visual cortex

Abstract

The exquisite capacity of primates to detect and recognize faces is crucial for social interactions. Although disentangling the neural basis of human face recognition remains a key goal in neuroscience, direct evidence at the single-neuron level is virtually nonexistent. We recorded from face-selective neurons in human visual cortex, in a region characterized by functional magnetic resonance imaging (fMRI) activations for faces compared to objects (i.e. the occipital face area, OFA). The majority of visually responsive neurons in this fMRI activation showed strong selectivity at short latencies for faces compared to objects. Feature scrambled faces and face-like objects could also drive these neurons, suggesting that the OFA is not tightly-tuned to the visual attributes that typically define whole human faces. These single-cell recordings within the human face processing system provide vital experimental evidence linking previous imaging studies in humans and invasive studies in animal models.

Face neurons encode nonsemantic features

“…Second, we predominantly studied multi- and single-unit spiking activity, whereas semantic information may be more relevantly encoded at the population level. Studies have generally found the same category selectivity in face patches using noninvasive imaging, single-unit activity, or multiunit activity ( 8 , 29 ), but detailed tuning patterns likely differ, as they do even among face neurons. Thus, it is conceivable that single neurons may respond to face-related features at the same time that population activity encodes semantic categories ( 11 ).…”

“…Face-selective neural signals have also been found in humans by intracranial field potential recordings ( 6 ); subsequently, by noninvasive measurements (e.g., ref. 7 ); and recently, with unit recordings ( 8 ).…”