M. A. J. Lourens

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OBJECTIVE Characterization of the functional neuronal activity and connectivity within the subthalamic nucleus (STN) in patients with Parkinson's disease (PD). METHODS Single units were extracted from micro-electrode recording (MER) of 18 PD patients who underwent STN deep brain stimulation (DBS) surgery. The firing rate and pattern of simultaneously(More)
OBJECTIVE The aim of this study was to investigate whether directional steering through a novel 32-contact electrode is safe and can modulate the thresholds for beneficial and side effects of stimulation. METHODS The study is a single-center, performance and safety study. Double-blind intraoperative evaluations of the thresholds for therapeutic benefit(More)
We present a computational model of a thalamocortical relay neuron for exploring basal ganglia thalamocortical loop behavior in relation to Parkinson's disease and deep brain stimulation (DBS). Previous microelectrode, single-unit recording studies demonstrated that oscillatory interaction within and between basal ganglia nuclei is very often accompanied by(More)
The motor disorder of Parkinson’s disease (PD) results from injury of the basal ganglia (BG). Understanding of the pathophysiology came late, especially with regard to the involvement of the substantia nigra. The description of ’shaking palsy’ or ’paralysis agitans’ (Parkinson, 1817) did not bring forward the recognition of its pathological origin. Lewy(More)
BACKGROUND A new 32-contacts deep brain stimulation (DBS) lead, capable of directionally steering stimulation, was tested intraoperatively. OBJECTIVE The aim of this pilot study was to perform recordings from the multidirectional contacts and to investigate the effect of directional current steering on the local field potentials (LFPs). METHODS In eight(More)
OBJECTIVE Continuous application of high-frequency deep brain stimulation (DBS) often effectively reduces motor symptoms of Parkinson's disease patients. While there is a growing need for more effective and less traumatic stimulation, the exact mechanism of DBS is still unknown. Here, we present a methodology to exploit the plasticity of GABAergic synapses(More)
In advanced Parkinson’s disease (PD), deep brain stimulation (DBS) can be used to disrupt the pathological activity in the basal ganglia, thereby reducing the PDmotor symptoms. The standard protocol for DBS, continuous high frequency stimulation of target cells, is applied notably in subthalamic nucleus (STN) or globus pallidus pars interna. It is proposed(More)
Two field trials, one with suckling Merino ewe lambs and the other with yearling Dohne Merino rams, are described. In these the anthelmintic efficacy of febantel (a benzimidazole), ivermectin, levamisole and morantel are compared, using the 1st stage larval reduction test. The mean natural log (+1 for zero values) of the post treatment larval counts of the(More)
The pedunculopontine nucleus has been suggested as a target for DBS. In this paper we propose a single compartment computational model for a PPN Type I cell and compare its dynamic behavior with experimental data. The model shows bursts after a period of hyperpolarization and spontaneous firing at 8 Hz. Bifurcation analysis of the single PPN cell shows(More)
Introduction In advanced Parkinson’s disease (PD), deep brain stimulation (DBS) can be used to disrupt pathological activity in the basal ganglia, thereby reducing PD motor symptoms. The standard protocol for DBS, continuous high frequency stimulation of target cells, is applied notably in subthalamic nucleus (STN) or globus pallidus pars interna. It is(More)