Evaluation of cortical excitability by motor and phosphene thresholds in transcranial magnetic stimulation

Prefrontal TMS produces smaller EEG responses than motor-cortex TMS: implications for rTMS treatment in depression

“…The motor and visual cortices have been shown to react differently to TMS; the subjectively detected phosphene threshold (PT) is significantly higher than the MT determined with electromyographic recording from peripheral target muscle, with no correlation between them (Boroojerdi et al 2002;Gerwig et al 2003;Stewart et al 2001). In these studies, the MT was measured from peripheral muscles by EMG reflecting only indirectly the excitability of the motor cortex, because these responses might be modulated by spinal mechanisms Nielsen et al 1999).…”

Repetitive Transcranial Magnetic Stimulation over the Right Dorsolateral Prefrontal Cortex Disrupts Digit Span Task Performance

“…This is at 90% of the average motor threshold observed in a previous experiment from our laboratory [16] , also in a student population. The use of a single intensity for all subjects was based on previous studies [17,18] , and on the consideration that individualized motor thresholds might not reflect excitability of other cortical areas [19] .…”

Scotomas induced by multiple, spatially invariant TMS pulses have stable size and subjective contrast

“…remaining uninfluenced. This of course is different from what may be assumed when phosphenes (sensation of a brief flash that brings in new RS-independent qualities to visual experience) are produced by TMS (e.g., Kammer, 1999;Fernandez et al, 2002;Gerwig et al, 2003;Kammer et al, 2005a,b;Stewart et al, 2001). Since in case of phosphenes, new perceptible phenomena are generated, the noise-generation account could be preferred to explain phosphene production.…”

“…For example, impairment of visual perception by masking with TMS has been widely investigated (Kammer, 2007;Ro, 2008;Amassian et al, 1989Amassian et al, , 1993Chiang et al, 2004;Corthout et al, 2000;Harris et al, 2008;Kammer et al 2005a,b;Overgaard et al, 2004;Ro et al, 2003Ro et al, , 2004. In addition to masking, artificial visual sensations or percepts called phosphenes can be produced (Gerwig et al, 2003;Kammer et al, 2005b;Ramos-Estebanez et al, 2007).…”