Table 1. Details of Electrical Stimulation Procedure and Subjective Reports.
Maximum stimulation settings, with patient responses of electrode pairs which induced a forced thought reponses, and adjacent electrode pairs. Electric stimulation was delivered using biphasic square wave pulses between 2 adjacent electrode contacts. Stimulation occurred between 1-15 mA using a 500 μs width pulse at a frequency of 50 Hz, with a maximum train duration of 2-5 seconds. The stimulating current was manually controlled during the stimulation, starting at 1 mA and gradually increasing in increments of 1-4 mA until a minimum of 10 mA was achieved (with a maximum threshold of 15 mA), a functional response (i.e. loss or gain of function) was observed, or prolonged afterdischarges were detected. Patients were asked to describe any cognitive, perceptual, sensory, or motor phenomena they experienced during or after each stimulation trial.
| Stimulation Location (Brodmann Area) |
Electrode 1 | Electrode 2 | Stim Intensity (mA) |
Stim Duration (sec) |
Patient Response |
|---|---|---|---|---|---|
| Patient 1 | |||||
| Left dorsolateral prefrontal cortex/ Rostral middle frontal gyrus (BA 9, 46) | GA1 | GA2 | 11.7 | 1-3.3 | Visual naming impairment |
| GA3 | −GA4 | 11.9 | 1.5-3.9 | Forced thought about a game show “she used to watch on TV but had not seen in years.” | |
| GA5 | GA6 | 6.0 | 1.7 | No response | |
| GA9 | GA10 | 12.7 | 1.7 | Visual naming impairment | |
| GA11 | GA12 | 11.9 | 1.6-2.7 | No response | |
| GA13 | GA14 | 6.0 | 2.6 | Motor response (rightward tongue deviation) | |
| Patient 2 | |||||
| Left dorsolateral prefrontal cortex/ Rostral middle frontal gyrus (BA 9, 46) | GA1 | GA2 | 11.6 | 1.0-4.9 | Visual naming impairment |
| GA3 | GA 4 | 11.7 | 1.0-3.7 |
Forced thought about an [unfamiliar] individual, unable to report name, physical characteristics, or relationship. Visual naming impairment |
|
| GA5 | GA6 | 5.0 | 1.0 | No response | |
| GA9 | GA10 | 11.7 | 1.0-4.9 | No response | |
| GA11 | GA12 | 6.8 | 1.0 | Speech arrest | |
| GA13 | GA14 | 5.8 | 1.6 | Motor response (rightward tongue deviation) | |
| Patient 3 | |||||
| Pars triangularis (BA 45) | G17 | G18 | 14.4 | 1.5-5.0 | “Memory of something that I can’t describe.” |
| Pars orbitalis (BA 47) | G25 | G26 | 11.6 | 1.0-5.0 | Memory of a child’s game. “I had a thought about a game that kids play in the summer, I can’t think of the exact game.” |
| G3 | G11 | 12.5 | 1.0-5.0 | Visual naming impairment | |
| G17 | G25 | 11.5 | 1.0-4.9 | Complex auditory phenomena | |
| G18 | G26 | 14.6 | 1.0-4.5 | Hears unfamiliar voice as an echo | |
| G19 | G27 | 5.8 | 2.2 | Ipsilateral pain | |
| G34 | G42 | 12.1 | 1.0-4.3 | Auditory hallucination (hears a familiar song playing) | |
| G41 | G42 | 11.6 | 1.0-4.9 | Language (comprehension) | |