Dissociable Effects of Urgency and Evidence Accumulation during Reaching Revealed by Dynamic Multisensory Integration

Area of Science:

• Neuroscience
• Motor Control
• Human Perception

Background:

• Humans integrate multisensory information for perceptual decisions, influenced by uncertainty.
• The brain's integration of multisensory feedback during movement and influencing factors beyond sensory uncertainty are not fully understood.

Purpose of the Study:

• To investigate how movement corrections to combined visual and mechanical perturbations scale with visual uncertainty.
• To explore the dynamics of multimodal feedback responses by varying movement time and visual feedback duration.

Main Methods:

• Two reaching experiments were conducted on healthy adults.
• Movement corrections to visual and mechanical perturbations were analyzed.
• An optimal feedback control model was used to interpret results.

Main Results:

• Visual feedback contribution decreased with increasing visual uncertainty.
• Faster movements showed stronger visual feedback responses during a transient phase.
• Longer visual feedback duration increased visual contributions during slow movements.
• Muscle activity modulated with sensory uncertainty and movement speed.

Conclusions:

• Movement corrections are influenced by sensory uncertainty, movement speed, and feedback duration.
• Urgency-dependent control gains and sensory evidence accumulation play roles in reaching control.
• Reaching control and decision-making share mechanisms involving sensory evidence accumulation and response urgency.