title: Electroencephalographic lateralization, clinical correlates and pharmacological response in untreated Parkinson's disease.
abstract: BACKGROUND
  In Parkinson's disease (PD), different topographically defined cortical-subcortical oscillatory networks have been implicated in motor program dysfunction. Few studies have focused on clinical correlates of cortical activity asymmetry using quantitative electroencephalography.
  
  
  METHODS
  We retrospectively selected N = 34 L-dopa naïve PD subjects who had undergone standardized electroencephalography. We selected N = 18 subjects group-matched by age, sex and hand dominance with normal electroencephalography and no parkinsonism and/or cognitive decline as controls. A Welch's periodogram was applied to electroencephalographic signal epochs recorded from homologous pairs of electrodes over each hemisphere. An index of lateralization was then obtained as the absolute value of the electroencephalographic asymmetry index, computed by subtracting left from right-sided log power spectral density for each homologous site and frequency band. A standardized L-dopa acute challenge test was performed on all PD subjects to compute short-duration response magnitude.
  
  
  RESULTS
  In mid/lateral frontal regions higher index of lateralization for the beta band (p = 0.015) and lower index of lateralization for the theta band (p = 0.036) were found in PD subjects as compared to controls. Both parameters correlated with Hoehn-Yahr staging (beta: r = 0.428, p = 0.012; theta: r = -0.464, p = 0.006). In occipital region lower index of lateralization for the alpha band was found in PD correlating with L-dopa short-duration response magnitude (r = 0.456; p = 0.007).
  
  
  CONCLUSIONS
  Lateralization of frontal cortex beta electroencephalographic activity is associated with clinical disability. Occipital cortex alpha activity may relate to L-dopa responsiveness in untreated PD subjects.
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mostile
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Nicoletti
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Dibilio
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Antonina
authors.initials: A
authors.lastname: Luca
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Pappalardo
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Loretta
authors.initials: L
authors.lastname: Giuliano
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Calogero Edoardo
authors.initials: CE
authors.lastname: Cicero
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Sciacca
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Loredana
authors.initials: L
authors.lastname: Raciti
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Contrafatto
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Bruno
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy.
authors.forename: Vito
authors.initials: V
authors.lastname: Sofia
authors.affiliation: Dipartimento GF Ingrassia, Sezione di Neuroscienze, Università Degli Studi di Catania, Catania, Italy. Electronic address: m.zappia@unict.it.
authors.forename: Mario
authors.initials: M
authors.lastname: Zappia
mesh_terms: D000368:Aged; D000513:Alpha Rhythm / Q000502:physiology; D000978:Antiparkinson Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001611:Beta Rhythm / Q000502:physiology; D002230:Carbidopa / Q000008:administration & dosage / Q000494:pharmacology; D004338:Drug Combinations; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000503:physiopathology*; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D012720:Severity of Illness Index
chemical_list: D000978:Antiparkinson Agents; D004338:Drug Combinations; C009265:carbidopa, levodopa drug combination; D007980:Levodopa; D002230:Carbidopa
keywords: Oscillatory networks; Parkinson's disease; Quantitative EEG index of lateralization; Short-duration response; l-dopa acute challenge test