Frontoparietal involvement in passively guided shape and length discrimination: a comparison between subcortical stroke patients and healthy controls

Abstract

Fifty to 85 % of patients with sensorimotor hemiparesis following stroke encounter impaired tactile processing and proprioception. Sensory feedback is, however, paramount for motor recovery. Sensory feedback through passively guided somatosensory discrimination exercises has been used in therapy, but so far, no studies have investigated which brain areas are involved in this process. Therefore, we performed a study with functional magnetic resonance imaging (fMRI) to examine brain areas related to discriminating passively guided shape and length discrimination in stroke patients and evaluate whether they differed from healthy age-matched controls. Eight subcortical stroke patients discriminated different shapes or length based on passive finger movements provided by an fMRI compatible robot. The data were contrasted to a control condition whereby patients discriminated music fragments. Passively guided somatosensory discrimination versus music discrimination elicited activation in similar frontoparietal areas in stroke patients compared to the healthy control group. Still, patients had increased activation in the right angular gyrus, left superior lingual gyrus, and right cerebellar lobule VI compared to healthy volunteers. Conversely, healthy volunteers activated the right precentral gyrus to a greater extent than patients. In both groups, shape discrimination resulted in anterior intraparietal sulcus and premotor activation, while length discrimination elicited a more medially located parietal activation with mainly right-sided premotor activity. The current study is a first step in clarifying brain activations during passively guided shape and length discrimination in subcortical stroke patients. Research into the effects of the use of sensory discrimination exercises on brain reorganization and brain plasticity is encouraged.

A neurocognitive approach for recovering upper extremity movement following subacute stroke: a randomized controlled pilot study

“…This is consistent with Perfetti’s concept of the hand10, 11 ) , considered as an essential element for the interaction with the objects inside the action, in which the movements of the more proximal segments are involved and acquire their significance. To do so, it should be noted that the exercises proposed for the hands included kinesthetic and tactile information due to their importance concerning hand functionality25, 26 ) . The evolution of both groups supports the importance of starting treatment as soon as possible33,34,35 ) and maintaining it for at least 10 weeks.…”

“…Moreover, it would indicate that favorable progression in UE movement depends mainly on parameters such as accuracy, fluidity, coordination or correlation between joints7, 32, 39, 40 ) . All of these are qualitative aspects in which sensory discrimination has an important role25, 26 ) .…”

“…During UE mobilizations and the contact with different surfaces, EG participants received the proposal of sensory discrimination tasks organized in a hierarchy (from lower to higher difficulty)12, 13, 22, 25, 26 ) (Table 1…”

“…; What surface do you think it is?”). Resolution of these tasks involved cognitive activation of learning strategies such as observation, motor imagery, imitation, etc12, 13, 25,26,27 ) . Every task was proposed as a problem to be resolved with closed eyes13, 22, 25, 26 ) .…”

“…Resolution of these tasks involved cognitive activation of learning strategies such as observation, motor imagery, imitation, etc12, 13, 25,26,27 ) . Every task was proposed as a problem to be resolved with closed eyes13, 22, 25, 26 ) . The physical therapist began with the most suitable task for each participant and continued with the following one after the satisfactory completion of the first task5, 12, 13 ) .…”