Neural activity reveals perceptual grouping in working memory

Area of Science:

• Cognitive Neuroscience
• Neuroscience
• Psychology

Background:

• The contralateral delay activity (CDA) is a well-established neural marker for visual object working memory capacity.
• Previous research has primarily linked CDA amplitude to the quantity of information held in visual working memory.

Purpose of the Study:

• To investigate whether the CDA also serves as an index for spatial working memory.
• To examine how different encoding strategies influence CDA modulation during spatial working memory tasks.
• To explore the neural basis of representing multiple spatial locations.

Main Methods:

• Scalp-recorded event-related potentials, specifically the CDA, were measured in participants performing spatial working memory tasks.
• Participants were instructed to encode either individual locations or grouped locations (constellations).
• Analysis focused on CDA amplitude and its modulation in relation to memory load and encoding strategy.

Main Results:

• CDA amplitude increased monotonically with the number of individual locations held in spatial working memory, mirroring findings for visual object memory.
• When locations were encoded as a constellation, the CDA showed a prolonged pattern and plateaued at a capacity of two locations.
• This suggests a shift in neural representation when spatial information is grouped.

Conclusions:

• The CDA is a versatile neural index reflecting the capacity of both visual object and spatial working memory.
• Encoding strategies significantly modulate CDA activity, providing neural evidence for the formation of unitary representations of multiple spatial locations.
• These findings advance our understanding of how the brain represents and manipulates spatial information in working memory.