Encoding of stimulus probability in macaque inferior temporal cortex.

Journal article

Optimal perceptual decisions require sensory signals to be combined with prior information about stimulus probability. Although several theories propose that probabilistic information about stimulus occurrence is encoded in sensory cortex, evidence from neuronal recordings has not yet fully supported this view. We recorded activity from single neurons in inferior temporal cortex (IT) whilst monkeys performed a task that involved discriminating degraded images of faces and fruit. The relative probability of the cue being a face vs. a fruit was manipulated by a latent variable that was not revealed to the monkeys, and which changed unpredictably over the course of each recording session. In addition to responding to stimulus identity (face or fruit), population responses in IT encoded the long-term stimulus probability of whether a face or a fruit stimulus was more likely to occur. Face-responsive neurons showed reduced firing rates to expected faces, an effect consistent with “expectation suppression”, but expected stimuli were decoded from multivariate population signals with greater accuracy. These findings support ‘predictive coding’ theories, whereby neural signals in the mammalian visual system actively encode and update predictions about the local sensory environment.

Authors: Bell, A; Summerfield, C; Morin, E; Malecek, N; Ungerleider, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Current Biology
• Volume: 26
• Issue: 17
• Pages: 2280-2290
• Publication date: 2016-08-01
• Acceptance date: 2016-07-06
• DOI: 10.1016/j.cub.2016.07.007
• EISSN: 1879-0445
• ISSN: 0960-9822
• Pmid: 27524483
• Language: English
• Keywords: decision making; neuron; monkey; predictive coding; decision-making; expectation suppression