Dimensional overlap between arrows as cueing stimuli and responses?. Evidence from contra-ipsilateral differences in...

Area of Science:

• Cognitive Neuroscience
• Human Motor Control
• Electrophysiology

Background:

• The lateralization at 400 ms (L-400) is an EEG potential difference observed after an arrow stimulus.
• Previous interpretations suggested L-400 indicates automatic manual response activation due to dimensional overlap.
• Kornblum et al.'s theory posits automatic priming requires responses within the response set.

Purpose of the Study:

• To investigate whether L-400 reflects automatic manual response activation based on Kornblum et al.'s theory.
• To examine the origin and function of L-400 by comparing manual and saccadic response tasks.
• To delineate the temporal and topographical characteristics of L-400.

Main Methods:

• Participants performed tasks requiring either key-press (manual) or saccadic (eye) responses to a second stimulus (S2) after an initial arrow stimulus (S1).
• EEG was recorded across the entire scalp, not just central sites over the hand-motor area.
• The lateralization at 400 ms (L-400) and lateralized readiness potential (LRP) were analyzed.

Main Results:

• L-400 was observed over the hand-motor area in manual response blocks, but was equally prominent in eye movement blocks.
• The topographical maximum of L-400 was anterior to the hand-motor-related negativity (LRP).
• L-400 did not align with the criteria for automatic manual response activation as defined by Kornblum et al.

Conclusions:

• L-400 does not signify automatic activation of manual responses.
• The findings suggest L-400 originates beyond the primary hand-motor cortex, potentially in the lateral premotor cortex.
• L-400 likely reflects the encoding of spatial arrow information for subsequent action preparation.