Neural Representations of Sensorimotor Memory- and Digit Position-Based Load Force Adjustments Before the Onset of...

Area of Science:

• Neuroscience
• Motor Control
• Human Sensorimotor Systems

Background:

• Dexterous object manipulation relies on anticipatory grip force adjustments.
• These adjustments are influenced by visual cues, sensorimotor memories, and digit positioning.
• Neural mechanisms underlying these separate anticipatory processes remain unclear.

Purpose of the Study:

• To identify distinct neural representations of sensorimotor memories and digit position integration during anticipatory grip force control.
• To investigate how the brain modulates forces based on recalled object properties versus real-time digit position sensing.
• To isolate and localize brain regions involved in these specific anticipatory mechanisms before object lift.

Main Methods:

• Functional magnetic resonance imaging (fMRI) and representational similarity analysis were employed.
• Human subjects performed a task requiring manipulation of an object with a concealed center of mass.
• Digit position was either constrained or unconstrained to vary reliance on sensorimotor memory versus online sensing.

Main Results:

• Cerebellar lobule regions (CrusII, VIIIa), ventral premotor cortex (PMv), and somatosensory areas showed sensitivity to sensorimotor memory content.
• Cerebellar lobule I-IV, Broca area 44, and PMv were sensitive to digit position variability, indicating integration of sensed position with force modulation.
• Voxel pattern differences correlated with matched/unmatched center of mass and constrained/unconstrained grasping conditions.

Conclusions:

• Neural representations for sensorimotor memory and digit position integration in anticipatory grip force control have been localized.
• Specific brain regions, including cerebellum and premotor cortex, play distinct roles in utilizing sensorimotor memory and adapting to digit position variability.
• This research advances understanding of the neural basis for adaptive, dexterous object manipulation.