Late emergence of synchronized oscillatory activity in the pallidum during progressive parkinsonism
European Journal of Neuroscience. 2007-09-14; 26(6): 1701-1713
DOI: 10.1111/j.1460-9568.2007.05777.x
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Leblois A, Meissner W, Bioulac B, Gross CE, Hansel D, Boraud T.
Parkinson’s disease is known to result from basal ganglia dysfunction.
Electrophysiological recordings in parkinsonian patients and animals have shown
the emergence of abnormal synchronous oscillatory activity in the cortico-basal
ganglia network in the pathological condition. In addition, previous studies
pointed out an altered response pattern during movement execution in the pallidum
of parkinsonian animals. To investigate the dynamics of these changes during
disease progression and to relate them to the onset of the motor symptoms, we
recorded spontaneous and movement-related neuronal activity in the internal
pallidum of nonhuman primates during a progressive dopamine depletion process.
Parkinsonian motor symptoms appeared progressively during the intoxication
protocol, at the end of which both animals displayed severe akinesia, rigidity
and postural abnormalities. Spontaneous firing rates did not vary significantly
after intoxication. During the early phase of the protocol, voluntary movements
were significantly slowed down and delayed. At the same time, the neuronal
response to movement execution was modified and inhibitory responses disappeared.
In contrast, the unitary and collective dynamic properties of spontaneous
neuronal activity, as revealed by spectral and correlation analysis, remained
unchanged during this period. Spontaneous correlated activity increased later,
after animals became severely bradykinetic, whereas synchronous oscillatory
activity appeared only after major motor symptoms developed. Thus, a causality
between the emergence of synchronous oscillations in the pallidum and main
parkinsonian motor symptoms seems unlikely. The pathological disruption of
movement-related activity in the basal ganglia appears to be a better correlate
at least to bradykinesia and stands as the best candidate to account for this
motor symptom.
DOI: 10.1111/j.1460-9568.2007.05777.x
PMID: 17880401 [Indexed for MEDLINE]