Task-specific role of ipsilateral pathways

Abstract

Task-specific neural coupling during cooperative hand movements has been described in healthy volunteers, manifested by bilateral reflex electromyographic responses in forearm muscles following unilateral ulnar nerve stimulation and by task-specific activation of secondary somatosensory cortical areas (S2) in functional MRI. The aim of this study was to investigate the role of sensory input to the ipsilateral and contralateral cortex during a cooperative task. Somatosensory evoked potentials from the ulnar nerve were recorded over the ipsilateral and contralateral cortex during resting and during cooperative and noncooperative hand movements. Ipsilateral potentials with smaller amplitude were present under all conditions in almost all participants. In relation to the resting condition, the amplitudes of both the ipsilateral and the contralateral potential were reduced during the cooperative and the noncooperative tasks. Nevertheless, the reduction in amplitude was similar for the ipsilateral and the contralateral potentials in the noncooperative task, but less on the ipsilateral compared with the contralateral side during the cooperative task. The ratio of ipsilateral/contralateral somatosensory evoked potential amplitude was thus significantly larger during the cooperative task compared with the control task and the resting condition. This indicates a functional role of ipsilateral pathways connecting the cervical spinal cord with the cortex during the cooperative task. These observations favor the idea of a task-specific mediation of sensory input from both hands to the ipsilateral and contralateral hemispheres as the basis of neuronal coupling.

Neural Consequences of Increasing Body Weight: Evidence from Somatosensory Evoked Potentials and the Frequency-Specificity of Brain Oscillations

“…In addition, the bilateral activation of S2 could witness the neural coupling of cooperative foot pressure as it was shown in cooperative hand movement (Dietz et al, 2015 ). For example Schrafl-Altermatt and Dietz ( 2014 ) have shown after unilateral forearm nerve stimulation a bilateral activation of S2 solely in cooperative hand movement and not during bilateral hand movements (i.e., non-cooperative). Since S2 is suggested to be involved in the integration of information from the both sides of the body (Lin and Forss, 2002 ), we hypothesized that S2 is involved in the neural processing of cooperative foot pressures onto the support surface.…”

Automatic gain control of neural coupling during cooperative hand movements

“…1 ) during cooperative hand movements in fifteen healthy subjects (age: 27.0 ± 6.2 years; 10 female/5 male). For the cooperative movement tasks a device was used that allowed counteractive rotations of handles, similar to that described previously 8 , 17 . With this device, movements were performed with rhythmic alternating antiphase wrist extension and flexion mimicking a “bottle opening” task (Fig.…”

Movement predictability modulates sensorimotor processing

“…A rest condition as well as three movement tasks–a predictable coupling task (COOP), an uncoupled task (NON), and an unpredictable coupling task (EXT)–were compared in all three experiments ( Figure 1 ). Participants were seated comfortably at a desk and performed rhythmic reciprocal (i.e., anti-phasic) wrist extension and flexion movements using one or two copies of a custom-built device described previously ( Schrafl-Altermatt and Dietz, 2014 ; Thomas et al, 2018 ). In short, it consists of two handles connected over a shoe-type brake and is mounted on a support.…”