Deep brain stimulation for Parkinson's disease: where do we stand?

Phase synchronization of coupled bursting neurons and the generalized Kuramoto model

Bursting neurons fire rapid sequences of action potential spikes followed by a quiescent period. The basic dynamical mechanism of bursting is the slow currents that modulate a fast spiking activity caused by rapid ionic currents. Minimal models of bursting neurons must include both effects. We considered one of these models and its relation with a generalized Kuramoto model, thanks to the definition of a geometrical phase for bursting and a corresponding frequency. We considered neuronal networks with different connection topologies and investigated the transition from a non-synchronized to a partially phase-synchronized state as the coupling strength is varied. The numerically determined critical coupling strength value for this transition to occur is compared with theoretical results valid for the generalized Kuramoto model.

The effects of bilateral subthalamic nucleus stimulation on cognitive and neuropsychiatric functions in Parkinson's disease: a case-control study (#)

INTRODUCTION

Parkinson's disease is one of the most disabling diseases which by electrode implantation and stimulation of subthalamic nucleus (STN), much progress has been made in the treatment of drug resistant patient. This new method of neurosurgery may have some neuropsychological side effects on the patients. The main aim of this study is to evaluate the effects of this kind of treatment on the different neuropsychological aspect of patients.

METHODS

The case-control study designed for comparing two groups of patients with Parkinson's disease. Thirty patients, who underwent electrode implantation and Deep Brain Stimulation (DBS), compare with 60 patients treated with antiparkinson's drugs. These two groups matched in age, sex, Parkinson's disease duration and Parkinson's severity scores.

MEASUREMENTS

the UPDR scale was used to assess the severity of the Parkinson's severity. Beck Depression Inventory questionnaire (BDI) and Hamilton Anxiety Rating Scale questionnaire (HARS) were used to evaluate the depression and anxiety consequences of DBS. Mini Mental Status Examination (MMSE) and Clock Drawing Test (CDT) were used to evaluate the cognitive and executive function of the study subjects.

RESULTS

Patients with STN stimulation showed lower level of anxiety and depression, however, the cognitive status were more deteriorated in study subjects than control group.

DISCUSSION

Patient with DBS surgery have to be followed up for neuropsychiatric symptoms particularly for the cognitive deterioration in long term period.