Abstract
Hyper-adaptability, the ability to adapt to changes in the internal environment caused by neurological disorders, is necessary to recover from various disabilities, such as motor paralysis and sensory impairment. In the recovery from motor paralysis, the pre-existing neural pathway of the ipsilateral descending pathway, which is normally suppressed and preserved in the course of development, is activated to contribute to the motor control of the paretic limb. Conversely, in sensory pathways, it remains unclear whether there are compensatory pathways which are beneficial for the recovery of sensory impairment due to damaged unilateral somatosensory pathways, such as thalamic hemorrhage. Here, we investigated the interaction between the left and right somatosensory pathways in healthy humans using paired median nerve somatosensory evoked potentials (SEPs). Paired median nerve SEPs were recorded at CP3 and CP4 with a reference of Fz in the International 10–20 System. The paired median nerve stimulation with different interstimulus intervals (ISIs; 1, 2, 3, 5, 10, 20, 40, 60, and 100 ms) was performed to test the influence of the first stimulus (to the right median nerve) on the P14, P14/N20, and N20/P25 components induced by the second stimulus (left side). Results showed that the first stimulation had no effect on SEP amplitudes (P14, P14/N20, and N20/P25) evoked by the second stimulation in all ISI conditions, suggesting that there might not be a neural connectivity formed by a small number of synapses in the left–right interaction of the somatosensory pathway. Additionally, the somatosensory pathway may be less diverse in healthy participants.
Highlights
Hyper-adaptability can be defined as the ability to adapt to changes in the internal environment caused by neurological disorders; it is essential for recovery from various disabilities
Left–Right Interactions in Somatosensory Pathway cord-lesions showed that the sprouting of midline-crossing axons of the corticospinal tract occurs in the spinal cord rostral to the lesion, and the sprouting was associated with improvement in hand function and locomotion (Courtine et al, 2005; Rosenzweig et al, 2010)
We investigated the interaction between contralateral and ipsilateral somatosensory pathways in healthy humans
Summary
Hyper-adaptability can be defined as the ability to adapt to changes in the internal environment caused by neurological disorders (e.g., stroke and spinal cord injury); it is essential for recovery from various disabilities. Brodie et al showed that the first stimulation to the right median nerve decreased the SEP amplitudes (P14/N20 and N20/P25) evoked by the second stimulation to the left median nerve with ISIs of 25–35 and 15–35 ms, respectively (Brodie et al, 2014) These studies indicate that interhemispheric inhibitory interactions in the SI occur between the two hemispheres through the corpus callosum in the critical time interval of 20–25 ms or 15–35 ms after median nerve stimulation (Ragert et al, 2011; Brodie et al, 2014). P-SEP recordings were obtained at nine different ISIs (1, 2, 3, 5, 10, 20, 40, 60, and 100 ms) to investigate the interaction between contralateral and ipsilateral activations at various levels in healthy humans
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
