Keyoumars Ashkan

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OBJECTIVE Brain-computer interfaces (BCIs) could potentially be used to interact with pathological brain signals to intervene and ameliorate their effects in disease states. Here, we provide proof-of-principle of this approach by using a BCI to interpret pathological brain activity in patients with advanced Parkinson disease (PD) and to use this feedback to(More)
OBJECTIVES To determine the effect of electrode contact location on efficacy of bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) for primary generalised dystonia (PGD). SUBJECTS AND METHODS A consecutive series of 15 patients with PGD (10 females, mean age 42 years, seven DYT1) who underwent bilateral GPi DBS, were assessed using the(More)
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) can be a highly effective treatment for Parkinson's disease (PD). However, therapeutic efficacy is limited by difficulties in consistently and correctly targeting this nucleus. Increasing evidence suggests that there is abnormal synchronization of beta frequency band activity (approximately 20(More)
We have examined dopaminergic cell survival after alteration of the subthalamic nucleus (STN) in methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. The STN was lesioned with kainic acid (B series) or underwent deep brain stimulation (DBS) at high frequency (C series). In another series, MPTP-treated and non-MPTP-treated monkeys had no STN(More)
BACKGROUND Although deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a highly effective therapeutic intervention in severe Parkinson's disease, its mechanism of action remains unclear. One possibility is that DBS suppresses local pathologically synchronised oscillatory activity. METHODS To explore this, the authors recorded from DBS(More)
Because of concerns about direct visualization of the subthalamic nucleus (STN) on magnetic resonance imaging (MRI), many functional neurosurgeons continue to rely on atlas-based coordinates to reach this target. T2-weighted MRI does allow direct visualisation of the STN. In order to compare the coordinates of the target point within the visualised STN with(More)
We report two cases of papillary glioneuronal tumour (PGNT). One was located in the supratentorial parenchyma and the other was intraventricular. Both patients underwent gross total resection of their tumour and have returned to normal lifestyle. Papillary glioneuronal tumor is a recently described rare cerebral neoplasm. Recently classified by the World(More)
We present a case of primary B-cell, large-cell, lymphoma of the skull vault in a 50-year-old HIV-positive male, who presented with a history of unilateral headache and a swelling on the scalp. Primary non-Hodgkin's lymphoma of the skull is rare, with only ten such cases in adults previously described. We suggest that this is the second reported case in an(More)
The subthalamic nucleus (STN) is thought to play a central role in modulating responses during conflict. Computational models have suggested that the location of the STN in the basal ganglia, as well as its numerous connections to conflict-related cortical structures, allows it to be ideally situated to act as a global inhibitor during conflict.(More)