Expectation modulates the response to subthalamic nucleus stimulation in Parkinsonian patients

Abstract

Expectations about future events are known to trigger neural mechanisms that affect both perception and action. Here we report that different and opposite expectations of bad and good motor performance modulate the therapeutic effects of subthalamic nucleus stimulation in Parkinsonian patients who had undergone chronic implantation of electrodes for deep brain stimulation. By analyzing the effects of subthalamic stimulation on the velocity of movement of the right hand, we found hand movement to be faster when the patients expected a good motor performance. The expectation of good performance was induced through a placebo-like procedure, thus indicating that placebo-induced expectations have influence on the treatment outcome. All these effects occurred within minutes, suggesting that expectations induce neural changes very quickly.

The psychology of neurofeedback: Clinical intervention even if applied placebo.

“…Placebo pills improve motor performance in Parkinsonian patients within minutes (Pollo et al, 2002) and sham-surgery can benefit patients for years (Moseley et al, 2002). Placebos can lift depression, inhibit pain, and even decrease antibody production in response to allergens (for a review of placebos, see Raz and Harris, 2016).…”

Unilateral subthalamic nucleus stimulation has a measurable ipsilateral effect on rigidity and bradykinesia in parkinson disease

“…Bradykinesia was quantified using the average of the middle ten seconds of rms velocity calculations for each fifteen-second trial (Pollo et al, 2002) using Origin statistical software (OriginLab, Northampton, MA). The rms velocity then was averaged for all three trials.…”

Placebo mechanisms across different conditions: from the clinical setting to physical performance

“…By manipulating the stimulator settings within 20 and 100 per cent of optimal values, and correctly or deceptively informing the patient about the stimulator condition, the experimenters observed better performance (i.e. faster movements) associated with positive expectation, thus validating DBS as an efficient tool to induce immediate motor placebo effects [46]. This knowledge was exploited in a subsequent work, taking advantage of the intra-operative need to ascertain the precise electrode localization by recording STN single-neuron electrical activity during implantation in awake patients.…”