THE BEREITSCHAFTSPOTENTIAL PRECEDING SIMPLE FOOT MOVEMENT AND INITIATION OF GAIT IN PARKINSONS-DISEASE

We compared the Bereitschaftspotential preceding a simple foot movemen t while sitting and a stepping movement while standing in a group of n ormal subjects and seven patients with mild to moderate Parkinson's di sease (PD) while off medication. None had major difficulties stepping to initiate gait. Electromyographic signals from tibialis anterior tri ggered the averaging of electroencephalographic signals from the scalp . Bereitschaftspotentials preceding a standing stepping movement were larger than those before a foot movement while sitting in normal subje cts, but no difference was observed in patients with PD. The absence o f an increase in the Bereitschaftspotential when stepping in PD may re flect an impairment of the preparation and assembly of the complex seq uences of movement necessary to initiate walking, even in the early st ages of the illness.