1. Autism Spectrum Disorder (ASD) is characterized by socio- communicative impairments, repetitive behaviors, and restricted interests with cases ranging from mild to severe. 2 Studies have found differences in psychophysiological activity such as heart rate and respiration in individuals with ASD compared to typically developing (TD) individuals during task performance. 1,3 This may be related to findings that individuals with ASD may be more sensitive to sensory stimuli due to attention abnormalities and may be slower to habituate to stimuli, thus incrementing the autonomic response. 4,5 In addition, psychophysiological activity has been found to index stress and anxiety, and in some fMRI studies has been associated with amygdala activation. 6,7 Average Heart Rate During the MRI Scan Average Respiration Rate During the MRI Scan 1.Althaus, M., et al.(2004). Autonomic response patterns observed during the performance of an attention-demanding task in two groups of children with autistic-type difficulties in social adjustment. Psychophysiology, 41: 893–904. 2.American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author. 3.Bal, E., et al. (2010). Emotion recognition in children with autism spectrum disorders: Relations to eye gaze and autonomic state. Journal of Autism and Developmental Disorders, 40(3), 358-370. 4.Hirstein, W., Iversen, P., & Ramachandran, V. S. (2001). Autonomic responses of autistic children to people and objects. Proceedings of the Royal Society of London Series B-Biological Sciences, 268, 1883– 1888. 5.Liss, M.; Saulnier, C.; Fein, D; Kinsbourne, M. (2006). Sensory and attention abnormalities in autistic spectrum disorders. Autism, 10, 155–172 6.Monk, C.S., et al. (2008). Amygdala and ventrolateral prefrontal cortex activation to masked angry faces in children and adolescents with generalized anxiety disorder. Archives of General Psychiatry. 2008;65(5):568-576. 7.Monk, C. S., et al. (2010). Neural circuitry of emotional face processing in autism spectrum disorders. Journal of psychiatry & neuroscience, 35(2), 105-114.  Experimental Design: o During resting state fMRI scanning, participants were instructed to stare at a fixation cross and not to think about anything in particular. o During task condition, participants participated in a task that examined top-down versus bottom-up processing in attention.  Psychophysiological Activity Acquisition: o Cardiac signal was obtained using a pulse oximeter placed on each participant’s finger and respiratory signal was obtained using a pressure belt around the abdomen during the fMRI study. o Physiological data were parceled out from fMRI data using MATLAB (2010B, The Mathworks, Natick, MA).  Data Analysis: o A two-way mixed factorial analysis of variance (ANOVA) was performed. The between-subject factor was group (ASD & TD) and within-subject factor was condition (resting state & task). o The statistical analysis was performed in SPSS.  No differences (condition X group) in heart beat emerged during the MRI scan.  No differences (condition X group) in respiration rate emerged during the MRI scan.  The results suggest that high-functioning adolescents with ASD do not display physiological signs of stress or anxiety during task-free resting periods.  They also suggest that high-functioning adolescents with ASD do not display increased physiological activity than TD adolescents during task conditions.  There is thus no evidence of effects of hypersensitivity on physiological activity during fMRI task performance.  Physiological differences therefore probably do not present a critical confound for fMRI task or resting state studies in high-functioning participants with ASD. Seventeen TD adolescents and sixteen adolescents with confirmed diagnosis of ASD (using DSM-IV, ADOS, and ADI). Groups were matched on age and IQ. Table 1 Participant Characteristics Note. Values are presented as mean (standard deviation) and range. Significance value, p, from two-sample independent t-tests for differences between the TD and ASD groups. Groups TD (n=17)ASD (n=16)p Age in years 14.0 (1.7) 12-17 14.31 (1.5) 12-17.58 Verbal IQ 105 (11.6) 83-126 108 (18.3) 72-147.66 Nonverbal IQ 107 (14.1) 77-129 110 (13.3) 84-140.49 Full scale IQ 107 (13.0) 78-126 110 (16.2) 81-141.50 The present study looked at possible psychophysiological differences influenced by hypersensitivity to stimuli between ASD and TD participants during an fMRI study. We specifically examined whether individuals with ASD would exhibit less psychophysiological activity during resting state condition compared to TD individuals, and whether such actvity would increase during task performance in ASD individuals. Funded by the SDSU MBRS-IMSD Program NIH/NIGMS Grant 2R25GM058906 ‐ 09A2, and by R01-MH081023. For correspondence or to obtain a copy of this poster, please e-mail omaximo88@gmail.com F(1, 29) =.420, p =.552 F(1, 29) = 1.305, p =.263