Microstimulation-induced inhibition as a tool to aid targeting the ventral border of the subthalamic nucleus
Bibliographic record
Abstract
Object The aim of the current study was to examine and compare the aftereffects of local high-frequency microstimulation through the recording electrode on the firing of neurons in the subthalamic nucleus (STN) and the substantia nigra pars reticulata (SNr) in patients undergoing surgery for deep brain stimulation. Deep brain stimulation has been playing an increasing role in the treatment of Parkinson disease, with the subthalamic nucleus (STN) being the preferred implantation target. Changes in cellular activity indicative of the borders of the STN are typically used during surgery to determine the extent of the STN and locate the optimal target, but in some cases borders may be difficult to identify. In this study the authors compared the effects of microstimulation in the SNr and STN. In previous studies they have shown that microstimulation in the internal globus pallidus, which is functionally similar to the SNr, inhibits firing, whereas similar microstimulation in the STN has minimal effect. The presence of inhibition in the SNr but not in the STN could be used as an additional criterion to help identify the location of the border between the STN and SNr. Methods Dual microelectrode recordings were performed during stereotactic surgery in 4 patients. Well-isolated high-amplitude units were stimulated extracellularly through the recording microelectrode with 0.5-second trains of high frequency (200 Hz) and low current (≤ 5 μA). Results In the majority (92%) of SNr neurons, this type of stimulation led to a period of inhibition lasting several hundreds of milliseconds following the end of the train. In contrast, only 1 neuron of 70 judged to be in the STN by other criteria was inhibited by this type of microstimulation, and this neuron was located at the ventral border of the STN. Conclusions These findings indicate that prolonged inhibition of firing following low-amplitude high-frequency microstimulation via the recording electrode is a consistent feature of almost all SNr neurons and rarely if ever occurs in STN neurons. This feature therefore provides a useful additional finding that can be used to help identify the border between the STN and SNr.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".