Hemi-Parkinson's disease: differential alterations during tactile perception

Abstract

The initial clinical manifestation of Parkinson's disease (PD) is frequently unilateral, with symptoms predominantly affecting the left (LPD) or right-side of the body (RPD). Although asymmetric affectation is characteristic of this disease, few studies have investigated its effects on non-motor systems. In the current fMRI study, we examined two tactile discrimination tasks in 24 PD patients ('ON') and 18 healthy-controls (HCs). Half of the patients were LPD and half RPD. The task consisted of separately applying pairs of sinusoidal vibratory stimuli at four locations on the index finger of both hands. Subjects were required to identify either the proximal or distal stimulus location, the simultaneous or successive presentation or simply respond to stimulus detection. Behavioural results revealed that the LPD differed from the HCs by exhibiting   poorer   performance.   In   contrast,   RPD patients behaved in similar manner to the HCs. Image data analysis revealed decreased cortical activity in the right intraparietal sulcus which was associated to lower performance in the LPD patients. These findings suggest that the LPD patients exhibited mild generalized perceptual inattention.  Our results demonstrate abnormal brain activity during tactile processing in PD patients depending upon clinical initiation onset.