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E32012 ACRM–ASNR Annual Conference Abstracts

Oral Presentations

Neuroscience Focus

Article 1 (NIDRR)Leg Preference Associated with Protective Stepping Responses toWaist-Pull Perturbations of Standing Balance in OlderAdults. Patricia M. Young (University of Maryland School ofMedicine, Baltimore, MD).

Disclosure: None disclosed.Objective: To determine whether leg preference influenced the

stepping response to a waist-pull perturbation of older adults at risk forfalls. Design: Non-randomized controlled trial. Setting: Balance and

alls Research Laboratory. Participants: Healthy, community-dwell-ng, older adult (� 65 years) volunteers (N � 59). Participants wererouped into low- and high-risk cohorts based on fall history in the 12onths prior to the study. More than one fall classified a participant as

high-risk”. Intervention: Participants received 60 lateral waist-pullerturbations of varying magnitude during quiet standing that evokedrotective stepping responses for balance recovery. Main Outcomeeasures: Number and type of steps taken following waist-pull

erturbation, leg preference defined by which leg was preferred ifsked to stand on one leg, minimum margins of balance stability atrst-step touchdown. Results: Mean number of recovery steps taken

increased in response to increased perturbation magnitude for allsubjects, regardless of whether the perturbation was to the preferred ornon-preferred side. Low fall-risk subjects took lateral side steps whenpulled to their preferred side and cross-over steps when pulled to theirnon-preferred side. In contrast, high fall-risk subjects frequently tookmore lateral steps when pulled to their non-preferred side. Variabilityof minimum margins of stability at first-step touchdown was greaterfor pulls to the non-preferred side for high fall-risk older adults.Conclusions: Leg preference may influence the protective steppingresponse to standing balance perturbations in older adults at risk forfalls. Such asymmetries in balance stability recovery may representa previously unrecognized precipitating factor for falls among olderindividuals and should be considered for rehabilitation interven-tions aimed at improving balance stability and reducing the riskof falls. Key Words: Diagnosis-independent; Motor function; Neu-roscience; Rehabilitation.

Article 2 (NIDRR)Differential Recruitment of Listening Strategies for AuditoryRhythms in Parkinson Disease. Nathaniel S. Miller (University ofMichigan, Ann Arbor, MI), Sariha I. Moyen, Rachael D. Seidler.Disclosure: None disclosed.

Objective: Impaired generation of an internal rhythm (or ‘beat’) ishypothesized to underlie the irregular timing of gait and speech inParkinson disease (PD; Freeman, Cody & Schady, 1993). Here, we testthis hypothesis by determining whether individuals with PD favor anon-beat, as opposed to beat-based, listening strategy for auditoryrhythms compared to controls. Design: Repeated-measures, group-comparison study. Setting: University research laboratory. Partici-

pants: A volunteer sample of 11 individuals with PD (ON medica-tion), 20 age-matched controls, and 14 young adult controls.

Interventions: Participants performed an auditory sequence timingtask shown to reveal individual differences in listening strategies foridentical rhythms in young adults (McAuley, Frater, Jancke & Miller,2006). For the task, participants heard tone sequences and judgedwhether the end of the sequence ‘sped up’ or ‘slowed down.’ Twosequence types were presented: 1) sequences for which participantsrecruit either a beat or non-beat listening strategy (test), as assessed bytheir proportion of ‘speeding up’ responses, and 2) sequences forwhich participants’ judgments are the same, regardless of listeningstrategy (control). Main Outcome Measure: Proportion of ‘speedingup’ responses for test and control sequences. Results: Individuals withPD recruit a non-beat based listening strategy more often than controls.Moreover, sequence discrimination thresholds do not explain thisdifference. Conclusions: These data provide additional support forimpairments in internal beat generation in PD. Additionally, this studylays the groundwork for the investigation of relationships betweentemporal processing strategies and the motor symptoms of PD thatmay inform rehabilitation. Key Words: Neurodegenerative disorder;Cognition and perception; Neuroscience; Rehabilitation.

Article 3 (NIDRR)Elucidating the Neurobiology of Self-Reported Fatigue in MultipleSclerosis (MS): The Interplay of Networks. Abhijit Das (KesslerFoundation Research center, West Orange, NJ).

Disclosure: None disclosed.Objective: To examine the correlation between fractional anisot-

ropy (FA), a measure of white matter integrity (WMI), and self-reported fatigue in patients with multiple sclerosis (MS). Back-ground: Fatigue – the most common and disabling symptom seen inpatients with MS – is a multifaceted and poorly understood phenom-enon; and likely to represent dysfunction of disparate neurocognitivenetworks. How different aspects of self-reported fatigue – psycholog-ical, cognitive or physical – correlates with WMI of the whole brain isunknown. Diffusion tensor imaging (DTI) allows evaluation of WMIin the whole brain. Participants and Methods: DTI data from 21patients (19 female) with relapsing remitting MS were processed usingFSL. Fatigue was assessed using the Modified Fatigue Impact Scale(MFIS), and each of its subscales – physical, cognitive and psychos-ocial – as well as the total score – were correlated with the FA mapsin a voxel-wise analysis. Results: The MFIS-physical subscore(21.2 � 8.1) correlated positively with FA scores in bilateral cingulate;and correlated negatively with bilateral precuneus. The MFIS-cogni-tive subscore (22.1 � 7.4) correlated positively with FA scores in WMtracts of bilateral basal ganglia; and correlated negatively with rightinsula. The MFIS-psychosocial subscore (4.3 � 1.9) correlated posi-tively with FA scores in WM tracts of right caudate; and correlatednegatively with right insula. Conclusions: These findings suggest that1) cognitive and psychosocial fatigue seem to rely on the samenetwork, and 2) this is different from the network underlying physicalfatigue. This fractionation represents a significant breakthrough inunderstanding the neurobiology of self-reported fatigue. Key Words:

Neurodegenerative disorder; Cognition and perception; Neuroscience;Rehabilitation.

Arch Phys Med Rehabil Vol 93, October 2012