Table 1.
Dopaminergic Effect of Brain Stimulation in Animals
| Article | Subjects (N) | Stimulation Parameters
|
Target Region | Methodology | Regional Changes | Findings | |||
|---|---|---|---|---|---|---|---|---|---|
| Method | Frequency | Intensity | Total pulses | ||||||
| Taber and Fibiger (1995) | Awake rats (6) | Electrical stimulation | 60 Hz | 50 μA 100 μA |
6420 | Bilateral PFC | Microdialysis | NAc | 38% ↑DA over 0–20 min 69% ↑DA over 0–20 min |
| Keck and others (2002) | Anesthetized rats (7) | rTMS (round coil) | 20 Hz | 130% RMT, 4.0 T | 1000 | Left frontal cortex | Microdialysis | Right dorsal HC | ~120% ↑DA over 0–30 min |
| Anesthetized rats (7) | Right NAc | ~30% ↑DA over 60–120 min | |||||||
| Anesthetized rats (6) | Right dorsal striatum | ~70% ↑DA over 30–120 min | |||||||
| Awake rats (6) | 300 | Right dorsal HC | ~120% ↑DA over 60–150 min | ||||||
| Awake rats (8) | Right NAc | ~40% ↑DA over 0–150 min | |||||||
| Zangen and Hyodo (2002) | Awake rats (8) | rTMS (round coil) | 2 Hz | 98% of max | 200 | Frontal cortex | Microdialysis | NAc | ~20% ↑DA, but returned to baseline at 30 min |
| Awake rats (8) | Caudal cortex | ~41% ↑DA, but returned to baseline at 30 min | |||||||
| Ben-Shachar and others (1997) | Rats (16–20) | rTMS (round coil) | 25 Hz | 2.3 T | 50 | Head | HPLC (decapitation at 10 s after rTMS) | HC Striatum Midbrain Frontal cortex |
18% ↑DA 25% ↑DA NS 26% ↓DA |
| Kanno and others (2004) | Awake rats (6) | rTMS (figure-of-eight coil) | 25 Hz | 60% of max (0.6 T), 110% RMT | 500 | PFC | Microdialysis | Right dorsolateral striatum | ~30% ↑DA over 0–110 min |
| Right PFC | NS | ||||||||
| 20% of max (0.2 T), 36% RMT | Right dorsolateral striatum | NS | |||||||
| 80% of max (0.8 T), 149% RMT | Right dorsolateral striatum | NS | |||||||
| Erhardt and others (2004) | Morphine-sensitized awake rats (8) | rTMS (round coil) | 20 Hz | 130% RMT, 4.0 T | 300 | Left frontal cortex | Microdialysis | Right NAc | ~55% ↑DA over 0–100 min |
| Control awake rats (8) | ~25% ↑DA, but returned to baseline at 40 min | ||||||||
| Ohnishi and others (2004) | Anesthetized monkeys (8) | rTMS (double coned coil) | 5 Hz | 35% of max | 2000 | Right M1 | [11C]raclopride PET | Left NAc Right NAc Right putamen |
8.2% ↓BP (↑DA) 8.12% ↓BP (↑DA) 10.51% ↑BP (↓DA) |
BP = binding potential; ↓ = decrease; DA = dopamine; HC = hippocampus; HPLC = high-performance liquid chromatography; ↑ = increase; NS = not significant; NAc = nucleus accumbens; PFC = prefrontal cortex; M1 = primary motor cortex; rTMS = repetitive transcranial magnetic stimulation; RMT = resting motor threshold. For microdialysis, the time shown in the Findings column reflects the time of measurement after the end of stimulation (e.g., 0 min refers immediately after the delivery of rTMS). For [11C]raclopride PET, the search region was limited to the striatum. Only those regions with a significant effect are shown in the table.