Functional magnetic resonance imaging (fMRI) studies have identified consistent age-related changes during various cognitive tasks such that older individuals display more positive and less unfavorable task-related activity than young adults. these groups in comparison to a young adult sample. Participants underwent fMRI during semantic fluency and transcranial magnetic stimulation to collect the ipsilateral silent period a measure of interhemispheric inhibition. Results indicated that sedentary older adults displayed reductions KPNA3 in unfavorable task-related activity compared to the active old group in areas of the attention network. Longer interhemispheric inhibition was associated with more unfavorable task-related activity in the right and left posterior perisylvian cortex suggesting that sedentary aging may result in losses in task facilitatory cortical inhibition. However these losses may be mitigated by regular engagement in physical exercise. advertisements. Younger participants were recruited from the University of Florida and the Gainesville community AG-1478 advertisements. Older adults were divided into Physically Active Older (PAO) and Sedentary Older (SO) groups based on self-reported physical activity level during a phone interview (refer to the Physical Activity Assessment and Group Assignment section). There were 15 participants in the PAO group (ages 60-85) and 12 in the SO group (ages 63-81) which was matched for age AG-1478 and education to the PAO group. Fourteen young adults (ages 19-37) comprised the Young Adult (YA) comparison group. Signed informed consent was obtained from all participants according to guidelines established by the Health Science Center’s Institutional Review Board at the University of Florida. Participants were compensated for their participation in the study. Refer to Table 1 for participants’ demographic and physical activity/fitness characteristics. Table 1 Participant demographics and behavioral characteristics AG-1478 Inclusion Criteria All participants were right-handed native English speakers who were deemed eligible for MRI AG-1478 scanning following an extensive screening protocol (e.g. no cardiac pacemaker ferrous metal implants or claustrophobia). Participants were apparently healthy and reported no history of diagnosed neurological conditions head trauma with loss of consciousness cardiac conditions learning disabilities attention deficit disorder alcohol or drug abuse or psychiatric conditions. Older adults currently prescribed beta-blockers for hypertension management and those with a AG-1478 resting heart rate >120 beats/min a systolic blood pressure >180 or a diastolic blood pressure >100 were excluded from the study. All participants scored ≥27 around the Mini-Mental State Examination [MMSE; (Folstein Folstein & McHugh 1975 Forty-nine participants were originally enrolled in the study; out of which 47 completed participation (2 were withdrawn due to inability to complete the imaging protocol). Of the remaining 47 1 SO participant was removed from analyses due to evidence of an ischemic event on MRI scan; 1 YA was excluded for non-compliance during the imaging session and 4 participants were removed due to image artifacts (1 YA 2 SO 1 PAO). The total sample comprised 41 participants (15 PAO 12 SO 14 YA) with 38 having iSP measures. Physical Activity Assessment and Group Assignment As we were interested in physical activity level over time (years) we chose to use self-report to differentiate groups rather than only a single direct fitness assessment (which was instead used as a validating measure). Participants were enrolled into the physically active group (PAO) if they reported continuous engagement of moderate to strenuous activity (at least 3 weekly 45-min exercise sessions) on a regular basis for more than 3 years contiguous to the report. Participants were enrolled into the sedentary group (SO) if they reported fewer than 45 min/week of moderate to strenuous weekly physical exercise. All younger participants were assigned to the young adult (YA) comparison group irrespective of their self-reported physical activity levels. To confirm self-reported physical activity levels and group assignment all participants were asked to undergo a 12-min distance challenge and to monitor their physical activity levels over a period of 7 days using a modified version of the Leisure-Time Exercise Questionnaire [LTEQ; (Godin Jobin & Bouillon 1986 Godin & Shephard 1985 The LTEQ is usually AG-1478 a three-item scale that asks participants to rate how often they.