Laser evoked potential recording from intracerebral deep electrodes.
OBJECTIVE
To investigate whether recording from deep intracerebral (IC) electrodes can disclose laser evoked potential (LEP) components generated under the cerebral cortex.


METHODS
LEPs were recorded to hand and/or perioral region stimulation from 7 patients suffering from Parkinson's disease, who underwent implant of IC electrodes in the globus pallidum pars interna (GPi), in the subthalamic nucleus (STN) and in the pedunculopontine nucleus (PPN). LEPs were obtained from the IC electrode contacts and from the Cz vertex, referred to the nose.


RESULTS
The scalp traces showed a triphasic response (P1-N2-P2). The IC electrodes recorded two main components (ICP2 and ICN2), showing the same latencies as the scalp N2 and P2 potentials, respectively. The ICP2-ICN2 complex was sometimes preceded by a ICP1 wave at the same latency of the scalp P1 response.


CONCLUSIONS
The LEP components recorded from the IC electrodes mirrored the ones picked up from the Cz lead, thus suggesting that they are probably generated by the opposite pole of the same cortical sources producing the scalp responses.


CONCLUSIONS
In the IC traces, there was no evidence of earlier potentials possibly generated within the thalamus or of subcortical far-field responses. This means that the nociceptive signal amplification occurring within the cerebral cortex is necessary to produce identifiable LEP components.
Valeriani
Massimiliano
M
Division of Neurology, Ospedale Pediatrico Bambino Gesù, IRCCS, Piazza Sant'Onofrio 4, 00165 Rome, Italy. m.valeriani@tiscali.it
Truini
Andrea
A
Le Pera
Domenica
D
Insola
Angelo
A
Galeotti
Francesca
F
Petrachi
Corrado
C
Mazzone
Paolo
P
Cruccu
Giorgio
G
D000368:Aged; D000704:Analysis of Variance; D001931:Brain Mapping; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D005917:Globus Pallidus / Q000503:physiopathology; D006225:Hand / Q000294:innervation / Q000528:radiation effects; D006801:Humans; D007834:Lasers; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000473:pathology; D011149:Pons / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000503:physiopathology