Transformed Visual Working Memory Representations in Human Occipitotemporal and Posterior Parietal Cortices

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Brain Function

Background:

• Recent fMRI studies suggest transformed representations in early visual cortex (EVC) between perception and visual working memory (VWM).
• This contrasts with the traditional sensory account of VWM, which posits shared representations based on cross-decoding.
• Previous inconsistencies were attributed to experimental task differences, not inherent representational distinctions.

Purpose of the Study:

• To directly compare target and distractor representations during the VWM delay period within equated perceptual and VWM tasks.
• To investigate whether representations for perception and VWM are shared or transformed in the human brain, particularly in the occipitotemporal cortex (OTC) and posterior parietal cortex (PPC).

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) in human participants (both sexes).
• Employed a task design equating perceptual and VWM task conditions to compare target and distractor representations.
• Applied cross-decoding analyses to fMRI data from OTC (including EVC) and PPC.

Main Results:

• Significant representational differences were found between distractors (perception) and targets (VWM) in both OTC and PPC.
• Differences were also observed between target encoding (perception) and delay (VWM) phases.
• Target representations were more invariant in PPC compared to OTC, suggesting regional differences in representation stability.

Conclusions:

• The findings contradict the sensory account of VWM, supporting a task-driven transformed representation model.
• Transformed representations, influenced by task goals and associative areas like PPC, better explain VWM function.
• This revised understanding is crucial for comprehending VWM representation in the human brain, including the EVC.