Induced movement in a patient is detected and correlated with a TMS
stimulating pulse so as to determine the patient's motor threshold
stimulation level. Direct visual or audible feedback is provided to the
operator indicating that a valid stimulation has occurred so that the
operator may adjust the stimulation accordingly. A search algorithm may
be used to direct a convergence to the motor threshold stimulation level
with or without operator intervention. A motion detector is used or,
alternatively, the motion detector is replaced with a direct motor evoked
potential (MEP) measurement device that measures induced neurological
voltage and correlates the measured neurological change to the TMS
stimulus. Other signals indicative of motor threshold may be detected and
correlated to the TMS stimulus pulses. For example, left/right asymmetry
changes in a narrow subset of EEG leads placed on the forehead of the
patient or fast autonomic responses, such as skin conductivity,
modulation of respiration, reflex responses, and the like, may be
detected. The appropriate stimulation level for TMS studies are also
determined using techniques other than motor cortex motor threshold
methods. For example, a localized ultrasound probe may be used to
determine the depth of cortical tissue at the treatment site. When
considered along with neuronal excitability, the stimulation level for
treatment may be determined. Alternatively, a localized impedance probe
or coil and detection circuit whose Q factor changes with tissue loading
may be used to detect cortical depth.