Diabetic peripheral neuropathy (DPN) (i.e., Type 2 Diabetes Mellitus and lower-extremity somatosensory impairments) is associated with a 15-fold increase in falls due to loss of balance. Our studies indicate that while some individuals with DPN can adapt and maintain balance, others cannot. Our project will examine the source of this adaptive capacity by determining the contribution of executive function (i.e., higher cognitive processes that modify information from other brain regions to modulate behavior) and the underlying prefrontal cortex to standing balance. ..We will recruit three groups of subjects: 1) older adults with DPN, 2) older adults with type 2 diabetes mellitus, but without somatosensory impairment, and 3) healthy age- and gender-matched controls. Subjects will complete neurophysiological and clinical tests of somatosensation, a balance assessment, cognitive exam, and structural and functional MR imaging of the brain at 3 Tesla. ..Aim 1 will determine if executive function and prefrontal cortex volume modify the effect of DPN on balance. We hypothesize that older adults with DPN will have worse balance than those without DPN; yet, in subjects with DPN, those with better executive function or larger prefrontal cortex volume will have better balance. ..Aim 2 will then provide a neural mechanism through which executive function may compensate for somatosensory impairment associated with DPN. Subjects will undergo functional MRI to determine regions of brain activation during pressure stimulation of the foot sole, both with and without the simultaneous performance of a cognitive task that challenges executive function. We hypothesize that 1) performing a cognitive task will reduce somatosensory cortical activation in response to foot sole stimulation in all subjects, and 2) the degree of somatosensory cortical activation during foot sole stimulation will correlate with measures of standing balance. ..These discoveries will indicate that older adults with DPN may utilize executive function and related brain regions to compensate for reduced sensory input via augmentation of the somatosensory cortical response to foot sole pressure stimuli. Rehabilitations strategies designed to exploit this compensatory mechanism and enhance the executive-based modulation of afferent input may minimize the deleterious effects of DPN on balance and fall risk.