Multisensory integration under visual target uncertainty during planning of reaching movements

by Lukas Karl-Heinz Amann
Doctoral thesis
Date of Examination:2024-11-06
Date of issue:2025-02-25
Advisor:Prof. Dr. Alexander Gail
Referee:Prof. Dr. Alexander Gail
Referee:Prof. Dr. Hansjörg Scherberger
Persistent Address: http://dx.doi.org/10.53846/goediss-11096

 

 

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Abstract

English

Movements are fundamental to human interaction and everyday function, relying on the integration of multiple sensory inputs for precise planning and execution. However, sensory uncertainty, particularly in the visual domain, can impair motor control, and the loss of proprioception due to injury or disease further exacerbates these deficits. Understanding how the brain integrates uncertain sensory information is essential for advancing the development of assistive technologies. This thesis addresses two main questions. The first question examines whether artificial vibrotactile stimulation can compensate for visual uncertainty in goal-directed reaching. By providing additional sensory cues about target location, I show that human participants integrate artificial somatosensory signals in a manner consistent with Bayesian optimal integration, improving movement accuracy despite unreliable vision. The second question focuses on the neural consequences of visual uncertainty by recording electrophysiological activity in the motor cortex of nonhuman primates. High uncertainty in target position disrupted motor goal encoding during movement planning, while feedback uncertainty impairs motor goal representations only when it is task critical, i.e., when having to rely on the sensory feedback and no other more reliable sensory modalities are available. Additionally, target uncertainty is encoded along near-orthogonal neural dimensions, potentially enabling separation of decision-making and movement-related processes. Together, these studies provide novel insights into the neural mechanisms of multisensory integration and motor planning under visual uncertainty.
Keywords: Movement planning; Visual uncertainty; Multisensory integration; Psychophysics; Electrophysiology; Vibrotactile stimulation; Motor cortex
 
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