PMID-18701754[0] Neuronal activity of the human subthalamic nucleus in the parkinsonian and nonparkinsonian state
- Recorded from the STN in both PD and ET patients -- with the ET patients acting as a control (sorta; as good as we'll get).
- ET is common neuromotor condition that involves intention tremor and movement overshoot; progresses over many years.
- Malfunction of the olivocerebellar pathways.
- no involvement of Dopamine-dependent pathways.
- 65 PD patients!
- Classified single units based on ISI & the asymmetry index, the ratio of the mode to the mean of the ISI histogram.
- bursting or burstlike firing, intermitten grouped firing separated by periods of pauses.
- Further analyzed for burstlike features via 'burst surprise method' Salcman 1985).
- irregular, broad ISI CV > 85.
- Regular tonic firing, bell shaped ISI, CV < 90.
- PD patients had more burst-like neurons; ET patients had more irregular neurons.
- Neurons with theta and beta characteristics predominated in bursting neurons (71/81); gamma oscillationgs were commonly found in nonbursting cells (8/11).
- Only found synchronized beta activity in SUAs recorded from PD patients.
- Levy: emphasized the importance of tremor for beta-band oscillations because the majority of synchronous cells were recorded from five patients with resting tremor in the operating room, whereas no synchronous pairs were found in nontremulous patients.
- aha! a limitation of our study, however, is the lack of tremor recordings during surgeries // we were therefore not able to determine the amount of tremor-locked activity within the 3-10 Hz or transient changes in response to intermittent tremor.
- Another limitation: no movements, attention could have wandered.
- Still, STN firing rate increased, as per MPTP model.
- Shift toward bursting type activity in PD.
- Did not find differences in the proportion of neurons exhibiting intrinsic oscillatory activity or interneuronal synchronization.
- Large proportion of neurons exhibiting theta-band activity around 4Hz in PD patients; c.f. monkeys, 10 Hz activity dominates.
- Tremor is not an accurate reporter of pathology.
____References____
[0] Steigerwald F, Pötter M, Herzog J, Pinsker M, Kopper F, Mehdorn H, Deuschl G, Volkmann J, Neuronal activity of the human subthalamic nucleus in the parkinsonian and nonparkinsonian state.J Neurophysiol 100:5, 2515-24 (2008 Nov) |
|