Firing rates of pallidal neurons are similar in Huntington's and Parkinson's disease patients

• Published in: Experimental brain research Vol. 166; no. 2; pp. 230 - 236
• Main Authors: TANG, Joyce K. H, MORO, Elena, LOZANO, Andres M, LANG, Anthony E, HUTCHISON, William D, MAHANT, Neil, DOSTROVSKY, Jonathan O
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.10.2005; Springer Nature B.V
• Subjects: Action Potentials - physiology; Adult; Biological and medical sciences; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Female; Fundamental and applied biological sciences. Psychology; Globus Pallidus - cytology; Globus Pallidus - physiopathology; Humans; Huntington Disease - physiopathology; Male; Medical sciences; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Neurology; Neurons - physiology; Parkinson Disease - physiopathology; Periodicity; Vertebrates: nervous system and sense organs; Human; Nervous system diseases; Basal ganglia; Parkinson's disease; Central nervous system; Discharge pattern; Electrophysiology; Parkinson disease; Globus pallidus; Basal ganglion; Huntington's disease; Cerebral disorder; Neuron; Central nervous system disease; Degenerative disease; Single-unit recordings; Extrapyramidal syndrome
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-005-2359-x

According to the now classical basal ganglia-thalamocortical circuitry model, the chorea of Huntington's disease (HD) and the hypokinesia in Parkinson's disease (PD) are explained by a decrease in the inhibitory output (reduced firing rates) from the globus pallidus internus (GPi) in HD and increased output in PD. Differences between firing patterns might also be a factor contributing to the different symptoms, however. To test the predictions of the model we examined neuronal firing rates and patterns in two HD patients and 14 PD patients. Single-cell, microelectrode recordings were obtained from awake patients undergoing stereotactic surgery for implantation of deep brain stimulating (DBS) electrodes in the GPi. The mean neuronal firing rate in the GPi of HD patients was 81.8+/-4.3 Hz (mean+/-SEM), which was not significantly different from that in PD patients (89.9+/-3.0 Hz). Firing pattern analyses using measurements of burst index, coefficient of variation, and percentage participation of spikes in bursts revealed, however, that GPi neurons in HD patients fired in a more regular pattern (fewer "bursts") than in PD patients. These results suggest that the rate-based model does not adequately explain the motor abnormalities present in the two HD patients studied. Furthermore, the findings did reveal a difference between firing patterns in the HD and PD groups, thereby supporting the role of altered firing patterns in the pathophysiology of these diseases.