Mike A Sambrook

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The 2-deoxyglucose metabolic mapping technique has been used to investigate the neural mechanisms which underlie the symptoms of Parkinsonism in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine primate model of Parkinson's disease. In six cynomolgus monkeys, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine was either (a) administered intravenously to induce(More)
Central to the neural mechanism of MPTP-induced parkinsonism is overactivity of the subthalamic nucleus. Lesion of the subthalamic nucleus has therefore been performed in two primates with this condition and found to produce a remarkable amelioration of the disorder.
The neural mechanisms that underlie both the anti-parkinsonian effects of dopamine agonists and dopamine agonist-induced dyskinesia were studied in parkinsonian primates, using the regional brain uptake of [3H]2-deoxyglucose (2-DG). Parkinsonian symptoms were induced in monkeys by the administration of the neurotoxin(More)
Experiments are described in which the gamma-aminobutyric acid (GABA) antagonist bicuculline was injected into the lentiform complex of conscious monkeys. Injections into either the lateral segment of the globus pallidus, or the medial part of the putamen, gave rise to chorea of the contralateral limbs and/or orofacial region. Control injections of vehicle(More)
OBJECTIVE Motor and cognitive function were compared in patients with Lewy body dementia, Parkinson's disease, or Alzheimer's disease, to identify features that may be clinically useful in differentiating Lewy body dementia from Alzheimer's disease and Parkinson's disease. METHODS A range of neuropsychological function and extrapyrimidal signs (EPS) was(More)
Dopamine D1 and D2 receptors located within the striatum (caudate nucleus and putamen) were studied autoradiographically, using [3H]SCH 23390 and [3H]sulpiride respectively, in (i) seven monkeys rendered parkinsonian by the systemic administration of MPTP, four of which were chronically exposed to anti-parkinsonian drugs (levodopa or apomorphine), (ii) two(More)
Antagonists of the neurotransmitter gamma aminobutyric acid (GABA) were injected at seventy intracerebral sites in the conscious monkey. Injections located in or near to the subthalamic nucleus provoked involuntary movements of the contralateral limbs. These movements had the characteristics of chorea and, when severe, resembled hemiballismus as seen(More)
Research into the neural mechanisms underlying the symptoms of parkinsonism utilizing the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-exposed primate model have shown that the subthalamic nucleus (STN) occupies a central role. As a logical development of this theory, we have studied the effects of thermocoagulative lesions of the STN in the primate(More)
Recent experimental data has made possible the description of the pathophysiological circuitry that mediates parkinsonism. This work has shown that dopamine-denervated striatal cells discharge abnormally and that this ultimately causes cells in the medial segment of the globus pallidus to become abnormally overactive. The main driving force behind the(More)
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces a profound parkinsonian state when systemically administered in monkeys and man. Previous studies have shown MPTP to be toxic to only the dopamine (DA) cells in the substantia nigra pars compacta and not to other catecholamine (CA)-containing cells. The data presented here suggest that MPTP also(More)