title: Practice-related changes in neural activation patterns investigated via wavelet-based clustering analysis.
abstract: OBJECTIVE
  To evaluate brain activation using functional magnetic resonance imaging (fMRI) and specifically, activation changes across time associated with practice-related cognitive control during eye movement tasks.
  
  
  METHODS
  Participants were engaged in antisaccade performance (generating a glance away from a cue) while fMR images were acquired during two separate test sessions: (1) at pre-test before any exposure to the task and (2) at post-test, after 1 week of daily practice on antisaccades, prosaccades (glancing toward a target), or fixation (maintaining gaze on a target).
  
  
  RESULTS
  The three practice groups were compared across the two test sessions, and analyses were conducted via the application of a model-free clustering technique based on wavelet analysis. This series of procedures was developed to avoid analysis problems inherent in fMRI data and was composed of several steps: detrending, data aggregation, wavelet transform and thresholding, no trend test, principal component analysis (PCA), and K-means clustering. The main clustering algorithm was built in the wavelet domain to account for temporal correlation. We applied a no trend test based on wavelets to significantly reduce the high dimension of the data. We clustered the thresholded wavelet coefficients of the remaining voxels using PCA K-means clustering.
  
  
  CONCLUSIONS
  Over the series of analyses, we found that the antisaccade practice group was the only group to show decreased activation from pre-test to post-test in saccadic circuitry, particularly evident in supplementary eye field, frontal eye fields, superior parietal lobe, and cuneus.
authors.affiliation: Department of Statistics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Jinae
authors.initials: J
authors.lastname: Lee
authors.forename: Cheolwoo
authors.initials: C
authors.lastname: Park
authors.forename: Kara A
authors.initials: KA
authors.lastname: Dyckman
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Lazar
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Austin
authors.forename: Qingyang
authors.initials: Q
authors.lastname: Li
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: McDowell
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D055815:Young Adult