title: Theta and alpha oscillations reflect differences in memory strategy and visual discrimination performance in patients with Parkinson's disease.
abstract: The aim of the present study was to investigate alterations in brain oscillatory activity during transient intentional encoding of abstract novel shapes in patients with Parkinson's disease (PD). Combined time-frequency analyses of alpha and theta power revealed a clear dissociation between PD patients (N=10) and age-matched healthy controls (N=10). PD patients used sub-optimal stimulus encoding strategies for subsequent maintenance and recall, whereas the controls mainly used categorization processes. In contrast to controls, PD patients showed significantly less theta increase and upper alpha suppression at frontal locations and significant laterality of early posterior theta and lower-2 alpha oscillations at right posterior locations. These findings suggest that the fronto-striatal circuits participate in visual categorization processes. Furthermore, theta and alpha oscillations appear to be involved in mediating the integration processes in mnemonic networks underlying visual categorization.
authors.affiliation: Institute for Psychology and Cognition Research, University of Bremen, Grazer Str. 4, Bremen D-28359, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Schmiedt
authors.forename: Anette
authors.initials: A
authors.lastname: Meistrowitz
authors.forename: Günter
authors.initials: G
authors.lastname: Schwendemann
authors.forename: Manfred
authors.initials: M
authors.lastname: Herrmann
authors.forename: Canan
authors.initials: C
authors.lastname: Basar-Eroglu
mesh_terms: D000368:Aged; D000513:Alpha Rhythm; D001683:Biological Clocks; D003342:Corpus Striatum / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008569:Memory Disorders / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010469:Perceptual Distortion / Q000502:physiology*; D010775:Photic Stimulation; D013826:Theta Rhythm; D014793:Visual Cortex / Q000503:physiopathology