Moving sounds within the peripersonal space modulate the motor system

Area of Science:

• Neuroscience
• Motor Control
• Sensory Integration

Background:

• The peripersonal space (PPS) is a multisensory representation of space around the body, crucial for interacting with the external world.
• The PPS integrates tactile, visual, and auditory information, particularly concerning the hand, and influences motor actions.
• It is unclear if PPS influences motor control only at specific locations or within a continuous action space.

Purpose of the Study:

• To determine the critical distance at which auditory stimuli affect hand corticospinal excitability.
• To investigate whether moving sounds approaching or receding from the hand have differential effects on motor control.
• To test if PPS representation affects the motor system within a continuous action space or only at specific locations.

Main Methods:

• Utilized Transcranial Magnetic Stimulation (TMS) to assess hand corticospinal excitability.
• Delivered TMS single pulses while participants perceived sounds at varying distances (15 cm to 90 cm) from their hand.
• Manipulated sound direction (approaching/receding) to evaluate its impact on motor responses.

Main Results:

• Hand corticospinal excitability (measured by MEPs amplitude) was significantly enhanced for sounds within approximately 60 cm of the hand.
• This enhancement occurred regardless of whether the sound was approaching or receding from the hand.
• The observed effect indicates a specific spatial boundary for PPS modulation of hand motor excitability.

Conclusions:

• Peripersonal space (PPS) representation creates a spatially defined zone that directly modulates hand motor system excitability.
• This modulation is distance-dependent, with a critical boundary around 60 cm, supporting a continuous action space rather than discrete locations.
• Findings highlight a strong link between multisensory spatial representation and the motor system's preparation for actions within that space.