Purpose: Examine the reliability of functional MRI activation over time in schizophrenic outpatients and non-patients while they complete WM tasks. Examine the outcome of Independent Components Analysis (ICA) denoising.

Methods: Participants: 8 schizophrenic outpatients and 9 non patient controlsIntersession interval: 6-7 weeksBehavioral Design: 0-back and 2-back working memory word and picture tasks fMRI Image Acquisition: Apparatus: Siemens 3T scanner with CP head coil, Styrofoam head cushion, and screen display 2 sec., 160 slice acquisitions, 3.5 mm slice thicknessfMRI Image Analysis: Pre-analysis: motion correction, smoothing, slice-timing correction ICA denoising: Manual removal of noise components visually identified as motion, physiological activity, and machine artifact Lower level analysis: Individual contrasts of 2-Back minus 0-Back with combined individual task contrasts Higher level analysis: General Linear Model

Discussion:Conclusions:Both groups had equally reliable behavioral performanceSchizophrenic patients had less reliable functional activation than non-patient participants. However, overall activation was greatly decreased for patientsICA denoising decreased reliability of activation for non- patients but increased it for patients. Therefore, noise may be more integrated with task activation in patients.

Implications and Future Directions:Need to compensate for difference in reliability of activation between schizophrenic patients and non-patient participantsCurrent ICA denoising method is inadequate; we need to develop better methods of noise identification and removalAnalyze reliability of activation for other tasks and regions

References:Aron, A. R., Gluck, M. A., & Poldrack, R. A. (2006). Long-term test-retest reliability of functional MRI in a classification learning task. NeuroImage, 29(3), 1000-1006.Manoach, D. S., Halpern, E. F., Kramer, T. S., Chang, Y., Goff, D. C., Rauch, S. L., et al. (2001). Test-retest reliability of a functional MRI working memory paradigm in normal and schizophrenic subjects. Am J Psychiatry, 158(6), 955-958.Raemaekers, M., Vink, M., Zandbelt, B., van Wezel, R. J. A., Kahn, R. S., & Ramsey, N. F. (2007). Test-retest reliability of fMRI activation during prosaccades and antisaccades. NeuroImage, 36(3), 532-542.Wei, X., Yoo, S.S., Dickey, C. C., Zou, K. H., Guttmann, C. R. G., & Panych, L. P. (2004). Functional MRI of auditory verbal working memory: long-term reproducibility analysis. NeuroImage, 21(3), 1000-1008.Winterer, G., Musso, F., Beckmann, C., Mattay, V., Egan, M. F., Jones, D. W., et al. (2006). Instability of prefrontal signal `processing in schizophrenia. American Journal of Psychiatry, 163(11), 1960-1968.

Acknowledgements:Research Mentor: Kristen Haut

Behavioral Results:Significantly reliable accuracy and d-prime between session one and session two for both patients and non-patients in both picture and word WM tasks

Test-retest reliability of fMRI in schizophrenic Test-retest reliability of fMRI in schizophrenic patientspatients

Maria C. PromMaria C. Prom Mentor: Angus MacDonald III, Ph.D. Mentor: Angus MacDonald III, Ph.D. Carleton CollegeCarleton College Department of Psychology, University of MN Department of Psychology, University of MN

Background:fMRI has become a central component in schizophrenia research, often with changes in brain activation over timefMRI activation in visual tasks and in auditory WM tasks has good test-retest reliability for non-patient participants (Aron, Gluck, & Poldrack, 2006; Wei et al., 2004).Test–retest reliability of activation during a WM task was found to be lower for schizophrenic patients than non-patient controls (Manoach et al., 2001).Low individual reliability is highly correlated with low signal to noise ratio (Raemaekers et al., 2007).Patients with schizophrenia have high-levels of residual noise variance which predicts their unstable and unreliable prefrontal activation (Winterer et al., 2006).

Hypotheses: Frontal activation will be less reliable for schizophrenic patients compared to non-patient participants. ICA noise removal will improve the reliability of activation for all participants and more-so for patients.

ICC 2-Back Picture

Controls: R= .660*

Patients: R= .841*

ICC 2-Back Word

Controls: R= .572*

Patients: R= .878*

* significant at p < .05

Imaging Results:Group-level voxel-based activation overlap: Picture WM Task (Voxel-based correction):Controls:

Before ICA denoising After ICA denoising Kappa derived = 0.67 Kappa derived = 0.74 Patients:

Before ICA denoising After ICA denoising Kappa derived = 0.06 Kappa derived = 0.00

Abstract:This research examined the test-retest reliability of fMRI activation in 8 schizophrenic outpatients and 9 non-patients. A 3T Siemens scanner measured brain activation while participants completed 0-back and 2-back working memory (WM) word and picture tasks. A manual ICA was completed to identify noise components for removal, those due to motion, physiological activity, and machine artifact. We examined the effect of ICA denoising on the reliability of activation. Group-level Region of Interest (ROI) percent overlaps demonstrated that schizophrenic patients have significantly less reliable activation in frontal regions than non-patients. Also, ICA denoising improved reliability of activation for non-patients but decreased it for patients.