title: Plastic phase-locking and magnetic mismatch response to auditory deviants in temporal lobe epilepsy.
abstract: The magnetic equivalent (MMNm) of mismatch negativity may reflect auditory discrimination and sensory memory. To study whether temporal lobe epilepsy (TLE) affects automatic central auditory-change processing, we recorded magnetoencephalographic (MEG) responses to standard and duration-deviant sounds in 12 TLE patients and 12 age-matched controls, and repeated MEG measurement in 8 patients 6-30 months following epilepsy surgery and in 6 controls 3-8 months after their first measurement. We compared the MMNm between patients and controls, and also evaluated intertrial phase coherences as indexed by phase-locking factors (PLF) using wavelet-based analyses. We observed longer MMNm latencies for patients than for controls. Dipole modeling and minimum-current estimates together showed bi-frontotemporal sources for MMNm. The phase locking across trials was dominant at the 4- to 14-Hz band, and the main difference in PLF between deviant- and standard-evoked responses occurred in the time frame of 150-250 ms after stimulus onset. Notably, in the 5 patients who became seizure free after removal of right temporal epileptic focus, the phase-locking phenomena resulting from deviant stimuli were enhanced, and even more distributed in the frontotemporal regions. We conclude that mesial TLE might affect auditory-change detection, and a successful surgery causes a possible plastic change in phase locking of deviant-evoked signals.
authors.affiliation: Institute of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan. yylin@vghtpe.gov.tw
authors.forename: Yung-Yang
authors.initials: YY
authors.lastname: Lin
authors.forename: Fu-Jung
authors.initials: FJ
authors.lastname: Hsiao
authors.forename: Yang-Hsin
authors.initials: YH
authors.lastname: Shih
authors.forename: Chun-Hing
authors.initials: CH
authors.lastname: Yiu
authors.forename: Der-Jen
authors.initials: DJ
authors.lastname: Yen
authors.forename: Sheong-Yeong
authors.initials: SY
authors.lastname: Kwan
authors.forename: Tai-Tong
authors.initials: TT
authors.lastname: Wong
authors.forename: Zin-An
authors.initials: ZA
authors.lastname: Wu
authors.forename: Low-Tone
authors.initials: LT
authors.lastname: Ho
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000293:Adolescent; D001303:Auditory Cortex / Q000503:physiopathology*; D001307:Auditory Perception; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology*; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008568:Memory; D009473:Neuronal Plasticity; D046709:Pattern Recognition, Physiological