PhD in Neuroscience

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Phd thesis

Deep brain stimulation and cognition in Parkinson’s Disease: towards an integrative neurophysiological model.

Deep Brain Stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for advanced Parkinson’s Disease (PD). Some evidence indicates a possible mild impairment of specific cognitive tasks (executive functions and verbal fluencies) with high frequency stimulation (HFS). Conversely, low frequency stimulation (LFS) is not associated with cognitive side effects, hence suggesting that, depending on the frequency of stimulation, STN-DBS may act not only on the motor basal ganglia networks, whose dysfunction is responsible for PD cardinal symptoms, but also on neural circuitries involved in cognition. The aim of this study is to better define the role of frequency of stimulation on cognitive outcomes. Furthermore, by means of quantitative EEG (qEEG) and event-related evoked potential (ERP), it will be investigated how different frequencies of stimulation modify spontaneous and evoked cerebral activity potentially related to cognition.

The research questions to address by the present project are: a) has low-frequency STN-DBS a different effect on cognitive functions than high-frequency STN-DBS?; b) are ERP and qEEG reliable objective measures for a quantitative, objective assessment of cognition-related brain activity in patients treated with STN stimulation at different frequencies?

Given these experimental questions, aims of the study will be the following: a) to identify and analyse differences in neuropsychological tests between low- and high-frequency STN stimulation conditions; b) to analyse and correlate qEEG and ERP with neuropsychological tests in different conditions of stimulation (i.e., low- and high-frequency STN stimulation conditions).

In order to address the research questions, the aims of the study will be pursued as follows: 

1. a) PD patients treated with STN-DBS will undergo a neuropsychological evaluation at both high- (130-185 Hz) and low-frequency (< 100 Hz) stimulation.
2. b) qEEG and P300 will be recorded from each patient at the same stimulation conditions, and data will be analysed according to neuropsychological tests and possible clinical or demographic confounders.

Research activities