title: Time dependent subthalamic local field potential changes after DBS surgery in Parkinson's disease.
abstract: Local field potentials (LFPs) recorded through electrodes implanted in patients with Parkinson's disease (PD) for deep brain stimulation (DBS) provided physiological information about the human basal ganglia. However, LFPs were always recorded 2-7 days after electrode implantation ("acute" condition). Because changes in the tissue surrounding the electrode occur after DBS surgery and could be relevant for LFPs, in this work we assessed whether impedance and LFP pattern are a function of the time interval between the electrode implant and the recordings. LFPs and impedances were recorded from 11 patients with PD immediately after (T-0h), 2 h after (T-2h), 2 days after (T-48h), and 1 month after (T-30d, "chronic" condition) surgery. Impedances at T-0h were significantly higher than at all the other time intervals (T-2h, p=0.0005; T-48h, p=0.0002; T-30d, p=0.003). Correlated with this change (p=0.005), the low-frequency band (2-7 Hz) decreased at all time intervals (p=0.0005). Conversely, the low- (8-20 Hz) and the high-beta (21-35 Hz) bands increased in time (low-beta, p=0.003; high beta, p=0.022), but did not change between T-48h and T-30d. Our results suggest that DBS electrode impedance and LFP pattern are a function of the time interval between electrode implant and LFP recordings. Impedance decrease could be related to changes in the electrode/tissue interface and in the low-frequency band. Conversely, beta band modulations could raise from the adaptation of the neural circuit. These findings confirm that results from LFP analysis in the acute condition can be extended to the chronic condition and that LFPs can be used in novel closed-loop DBS systems.
authors.affiliation: Centro Clinico per le Neuronanotecnologie e la Neurostimolazione, Fondazione IRCCS Ospedale Maggiore, Policlinico, Mangiagalli e Regina Elena, Università degli Studi di Milano, Milano, 20122 Milano, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Rosa
authors.forename: Sara
authors.initials: S
authors.lastname: Marceglia
authors.forename: Domenico
authors.initials: D
authors.lastname: Servello
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Foffani
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Rossi
authors.forename: Marco
authors.initials: M
authors.lastname: Sassi
authors.forename: Simona
authors.initials: S
authors.lastname: Mrakic-Sposta
authors.forename: Roberta
authors.initials: R
authors.lastname: Zangaglia
authors.forename: Claudio
authors.initials: C
authors.lastname: Pacchetti
authors.forename: Mauro
authors.initials: M
authors.lastname: Porta
authors.forename: Alberto
authors.initials: A
authors.lastname: Priori
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001703:Biophysics; D046690:Deep Brain Stimulation / Q000379:methods*; D004558:Electric Stimulation / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy*; D013057:Spectrum Analysis / Q000379:methods; D013223:Statistics as Topic; D020530:Subthalamus / Q000502:physiology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods