Dynamic modulation of corticospinal excitability and short-latency afferent inhibition during onset and maintenance phase of selective finger movement

Abstract

Objective During highly selective finger movement, corticospinal excitability is reduced in surrounding muscles at the onset of movement but this phenomenon has not been demonstrated during maintenance of movement. Sensorimotor integration may play an important role in selective movement. We sought to investigate how corticospinal excitability and short-latency afferent inhibition changes in active and surrounding muscles during onset and maintenance of selective finger movement. Methods Using transcranial magnetic stimulation (TMS) and paired peripheral stimulation, input-output recruitment curve and short-latency afferent inhibition (SAI) were measured in the first dorsal interosseus and abductor digiti minimi muscles during selective index finger flexion. Results: Motor surround inhibition was present only at the onset phase, but not at the maintenance phase of movement. SAI was reduced at onset but not at the maintenance phase of movement in both active and surrounding muscles. Conclusions Our study showed dynamic changes in corticospinal excitability and sensorimotor modulation for active and surrounding muscles in different movement states. SAI does not appear to contribute to motor surround inhibition at the movement onset phase. Also, there seems to be different inhibitory circuit(s) other than SAI for the movement maintenance phase in order to delineate the motor output selectively when corticospinal excitability is increased in both active and surrounding muscles. Significance This study enhances our knowledge of dynamic changes in corticospinal excitability and sensorimotor interaction in different movement states to understand normal and disordered movements.

Centre-surround organization of fast sensorimotor integration in human motor hand area

“…This finding indicates that fast cortical sensory-to-motor interactions are blocked in relaxed surrounding muscle during tonic contraction of a single hand muscle. This finding confirms previous single-site TMS studies which show a dynamically modification of SAI during movement preparation and execution (Asmussen et al, 2014(Asmussen et al, , 2013Cho et al, 2016;Classen et al, 2000). The context-dependent loss of homotopic SAI and heterotopic SAF in the surrounding muscle during an isolated tonic contraction may have a stabilizing function for feedforward control of tonic contraction, rendering the M1 HAND less sensitive to transient sensory input from the hand.…”

Effects of lorazepam and baclofen on short‐ and long‐latency afferent inhibition

“…, ; Cho et al . ). We recently reported that there is no significant relationship between afferent inhibition and tactile or motor performance (Turco et al .…”

“…J Physiol 596.21 movement planning (Voller et al 2005(Voller et al , 2006Richardson et al 2008;Ni et al 2011;Asmussen et al 2013Asmussen et al , 2014Cho et al 2016). We recently reported that there is no significant relationship between afferent inhibition and tactile or motor performance (Turco et al 2018b).…”

Fast Intracortical Sensory-Motor Integration: A Window Into the Pathophysiology of Parkinson’s Disease

“…In healthy individuals, SAI is consistently expressed at rest, but attenuated during finger movements (Dubbioso et al, 2017c). In the active target muscle, SAI was reduced at movement initiation during both mixed and homotopic cutaneous nerve stimulation (Asmussen et al, 2013; Cho et al, 2016), whereas SAI was reduced during the maintenance phase of the movement (Asmussen et al, 2013) or found to be normal (Cho et al, 2016). Accordingly, SAI and SAF by homotopic or heterotopic stimulation were abolished during the tonic contraction of the target muscle (Dubbioso et al, 2017c).…”