Electrocortical and behavioral responses produced by acute electrical stimulation of the human centromedian thalamic nucleus.
Incremental, desynchronizing and spike-wave electrocortical responses and concomitant symptoms to acute electrical stimulation of the centromedian thalamic nucleus (CM) were studied in 12 patients with intractable complex partial and tonic-clonic generalized seizures. Low-frequency (6/s), 320-800 microA stimulation of the caudal-basal and central portions of CM elicited incremental recruiting and augmenting-like responses with a bilateral regional scalp distribution, with emphasis at the ipsilateral frontal (recruiting) and central (augmenting) regions, while ventral-basal CM stimulation elicited primary-like responses with a focal distribution at the ipsilateral parietal region. High-frequency (60/s), 320-800 microA stimulation of caudal-basal and central, but not ventral-basal CM, elicited EEG desynchronization and a slow negative shift of the EEG baseline with scalp distribution similar to that showed by recruiting- and augmenting-like responses. Neither incremental nor desynchronization EEG responses were accompanied by evident patient sensory or motor responses. Low-frequency (3/s), high-intensity (30 V = 2400 microA) combined stimulation of the right CM and left non-specific mesencephalic ascending pathways elicited a response similar to the typical absence attack with all EEG and clinical ingredients: S1, S2, P1 and W components of the individual spike-wave complex and generalized spike-wave discharges followed by sleep spindle EEG afterdischarges, accompanied by motionless stare, 3/s eye blinking, lip smacking and total failure to respond to visual stimuli in patients under a simple responding task.
Velasco
M
M
U.M.R. Neurophysiology Unit, National Medical Center, IMSS, Mexico City, Mexico.
Velasco
F
F
Velasco
A L
AL
Brito
F
F
Jiménez
F
F
Marquez
I
I
Rojas
B
B
D001519:Behavior / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D017029:Epilepsy, Complex Partial / Q000175:diagnosis / Q000503:physiopathology*; D004829:Epilepsy, Generalized / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D008636:Mesencephalon / Q000502:physiology; D013787:Thalamic Nuclei / Q000502:physiology*