Neural Evidence for Different Types of Position Coding Strategies in Spatial Working Memory

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Brain Function

Background:

• Sustained neural activity in spatial working memory tasks suggests information maintenance but lacks mechanistic detail.
• This activity may represent stimulus position or motor response planning.
• Understanding spatial coding mechanisms requires examining different task demands.

Purpose of the Study:

• To investigate neural evidence for distinct spatial coding strategies in working memory.
• To differentiate between prospective motor coding and retrospective sensory coding.
• To explore how task characteristics influence these coding strategies.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used in two experiments with 75 participants.
• Participants performed a spatial working memory task involving remembering a target position.
• Task design manipulated response predictability independently of difficulty and retrieval.

Main Results:

• Prospective motor coding engaged somatomotor, premotor, and motor cortices with increased network integration.
• Retrospective sensory coding involved parietal regions and enhanced connectivity within visual and attentional networks.
• Differences in activation, dynamics, and network integration supported complementary coding strategies.

Conclusions:

• The brain employs distinct, complementary strategies for spatial working memory based on task demands.
• Prospective and retrospective coding mechanisms are neurally dissociable.
• These findings offer insights into the flexible neural basis of spatial information processing.