Concurrent maintenance of both veridical and transformed working memory representations within unique coding schemes

Area of Science:

• Cognitive Neuroscience
• Neuroscience

Background:

• Human working memory (WM) must continuously update limited information to guide behavior effectively.
• Previous research indicates WM representations transform before responses, removing irrelevant items.

Purpose of the Study:

• To investigate the neural representation of transformed WM information and its original, veridical form.
• To determine if discarded, task-irrelevant stimuli representations are fully removed or retained.

Main Methods:

• Multivariate pattern analysis (MVPA) applied to electroencephalographic (EEG) data.
• Perturbation of the representational network using a visual impulse stimulus during WM maintenance.
• Decoding of both veridical and mentally rotated orientation gratings from impulse-driven neural activity.

Main Results:

• Neural responses successfully decoded both veridical and transformed (mentally rotated) orientation gratings.
• Impulse response selectively reflected task-relevant (cued) items, indicating task-irrelevant (uncued) items were discarded.
• No-longer-task-relevant original stimuli representations persisted alongside transformed representations in distinct formats.

Conclusions:

• Working memory retains original stimulus representations even after transformation, alongside updated, task-relevant information.
• This dual representation, though seemingly inefficient, may enhance behavioral precision and flexibility in dynamic environments.
• Neural persistence of original representations suggests a more complex WM updating mechanism than simple removal of irrelevant information.