Temporal asymmetry of neural representations predicts memory decisions

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Memory Research

Background:

• Stimulus familiarity can arise from recent encounters, similarity to recent experiences, or typical experiences.
• Understanding how the brain processes these similarity sources for memory decisions is a key challenge.

Purpose of the Study:

• To investigate how the brain computes neural similarity across different temporal windows.
• To determine the neural basis of memory decisions based on temporal similarity.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Neural similarity was computed between current stimuli and past/future events across various timescales (seconds to days).
• Behavioral memory decisions were recorded on a trial-by-trial basis.

Main Results:

• Memory decisions were predicted by the temporal asymmetry in neural similarity (difference between past and future similarity).
• This temporal asymmetry effect was observed in lateral parietal and occipitotemporal cortices.
• The effect was strongest for recent past events (minutes) and when veridical memory was weak.

Conclusions:

• The brain supports memory decisions by comparing actual past experiences with predicted future events.
• Temporal asymmetry in neural similarity plays a crucial role in distinguishing old from new stimuli.
• This mechanism is particularly important for guiding memory judgments under conditions of uncertainty.