Biology subjects

Hackney, M. E.

Publications and source records attributed to Hackney, M. E..

7 recordsLinked to original sources

bioRxiv2026

Functional Reorganization of Motor Subcircuits in Parkinson's disease

Parkinsons disease disrupts motor control across multiple body parts, yet the neural mechanisms underlying these impairments remain incompletely defined. We compared resting-state functional connectivity in people with mild-to-moderate Parkinsons disease (n = 58) and neurotypical older adults (n = 24), focusing on regions implicated in internally generated (IG) and externally generated (EG) movement pathways. For our analysis, we leveraged the reproducible NeuroMark independent component template and motor effector-specific mapping of primary motor cortex (M1). Our results reveal both increased and decreased connectivity patterns in Parkinsons disease: M1 subregions associated with control of the leg, hand, and larynx showed robust increases in connectivity exclusively with cerebellar territories, particularly Crus II and Lobules VIIIa/VIIIb. The postcentral gyrus (primary somatosensory cortex) showed primarily increased connectivity with cerebellar regions and the insula. In contrast, the caudate nucleus displayed a mixed profile, with increased connectivity to the superior temporal gyrus and decreased connectivity to the superior medial frontal gyrus and cerebellar Crus II. Our motor effector-specific analysis of disease severity scores (MDS-UPDRS) in people with Parkinsons disease revealed mild impairments across all categories (leg, hand, larynx) but disproportionately greater hand-related deficits, suggesting that some of the observed M1 connectivity differences may be influenced by these behavioral asymmetries. These anatomically precise, effector-specific alterations suggest compensatory recruitment of cerebellar circuits in Parkinsons disease and provide a framework for targeting motor subcircuits in rehabilitation, including dance-based interventions.

neuroscience↗

bioRxiv2023

Associations between music and dance relationships, rhythmic proficiency, and spatiotemporal movement modulation ability in adults with and without mild cognitive impairment

BackgroundPersonalized dance-based movement therapies may improve cognitive and motor function in individuals with mild cognitive impairment (MCI), a precursor to Alzheimers disease. While age- and MCI-related deficits reduce individuals abilities to perform dance-like rhythmic movement sequences (RMS)--spatial and temporal modifications to movement--it remains unclear how individuals relationships to dance and music affect their ability to perform RMS. ObjectiveCharacterize associations between RMS performance and music or dance relationships, as well as the ability to perceive rhythm and meter (rhythmic proficiency) in adults with and without MCI. MethodsWe used wearable inertial sensors to evaluate the ability of 12 young adults (YA; age=23.9{+/-}4.2 yrs; 9F), 26 older adults without MCI (OA; age=68.1{+/-}8.5 yrs; 16F), and 18 adults with MCI (MCI; age=70.8{+/-}6.2 yrs; 10F) to accurately perform spatial, temporal, and spatiotemporal RMS. To quantify self-reported music and dance relationships and rhythmic proficiency, we developed Music (MRQ) and Dance Relationship Questionnaires (DRQ), and a rhythm assessment (RA), respectively. We correlated MRQ, DRQ, and RA scores against RMS performance for each group separately. ResultsThe OA and YA groups exhibited better MRQ and RA scores than the MCI group (p<0.006). Better MRQ and RA scores were associated with better temporal RMS performance for only the YA and OA groups (r2=0.18-0.41; p<0.045). DRQ scores were not associated with RMS performance in any group. ConclusionsCognitive deficits in adults with MCI likely limit the extent to which music relationships or rhythmic proficiency improve the ability to perform temporal aspects of movements performed during dance-based therapies.

neuroscience↗

bioRxiv2022

Motor and cognitive deficits limit the ability to flexibly modulate spatiotemporal gait features in older adults with mild cognitive impairment

IntroductionDance-based therapies are an emerging form of movement therapy aiming to improve motor and cognitive function in older adults with mild cognitive impairments (MCIs). Despite promising effects of dance-based therapies on function, it remains unclear how age-related declines in motor and cognitive function affect movement capacity and influence which movements and rhythms maximize dance therapy efficacy. Here, we evaluated the effects of age and MCI on the ability to accurately modulate spatial (i.e., joint kinematics), temporal (i.e., step timing), and spatiotemporal features of gait to achieve spatial and temporal targets during walking. MethodsWe developed novel rhythmic movement sequences - nine spatial, nine temporal, and four spatiotemporal - that deviated from typical spatial and temporal features of walking. Healthy young adults (HYA), healthy older adults (HOA), and adults with MCI were trained on each gait modification before performing the modification overground, with kinematic data recorded using wearable sensors. ResultsHOA performed spatial (p = 0.010) and spatiotemporal (p = 0.048) gait modifications less accurately than HYA. Individuals with MCI performed spatiotemporal gait modifications less accurately than HOA (p = 0.017). Spatial modifications to the swing phase of gait (p = 0.006, Cohens d = -1.3), and four- and six-step Duple rhythms during temporal modifications (p < 0.030, Cohens d > 0.9) elicited the largest differences in gait performance in HYA vs. HOA and HOA vs. MCI, respectively. DiscussionThese findings suggest that age-related declines in strength and balance reduce the ability to accurately modulate spatial gait features, while declines in working memory in individuals with MCI may reduce the ability to perform longer temporal gait modification sequences. Differences in rhythmic movement sequence performance highlight motor and cognitive factors potentially underlying deficits in gait modulation capacity, which may guide therapy personalization and provide more sensitive indices to track intervention efficacy.

synthetic biology↗

bioRxiv2020

Abnormal center of mass control during balance is associated with falls in Parkinson's disease

Although Parkinson disease (PD) causes profound balance impairments, we know very little about how PD impacts the sensorimotor networks we rely on for automatically maintaining balance control. In young healthy people and animals, muscles are activated in a precise temporal and spatial organization when the center of body mass (CoM) is unexpectedly moved that is largely automatic and determined by feedback of CoM motion. Here, we show that PD alters the sensitivity of the sensorimotor feedback transformation. Importantly, sensorimotor feedback transformations for balance in PD remain temporally precise, but become spatially diffuse by recruiting additional muscle activity in antagonist muscles during balance responses. The abnormal antagonist muscle activity remains precisely time-locked to sensorimotor feedback signals encoding undesirable motion of the body in space. Further, among people with PD, the sensitivity of abnormal antagonist muscle activity to CoM motion varies directly with the number of recent falls. Our work shows that in people with PD, sensorimotor feedback transformations for balance are intact but disinhibited in antagonist muscles, likely contributing to balance deficits and falls.

neuroscience↗

bioRxiv2019

Lower-limb rigidity is associated with frequent falls in Parkinson disease

BACKGROUND AND OBJECTIVEThe role of muscle rigidity as an etiological factor of falls in Parkinson disease (PD) is poorly understood. Our objective was to determine whether lower leg rigidity was differentially associated with frequent falls in PD compared to upper limb, neck, and total rigidity measures. METHODS: We examined associations between UPDRS-III (motor) rigidity subscores and history of monthly or more frequent falls in N=216 individuals with PD (age, 66{+/-}10 y; 36% female, disease duration, 7{+/-}5 y) with logistic regression. RESULTS: N=35 individuals were frequent fallers. Significant associations were identified between lower limb rigidity and frequent falls (P=0.01) after controlling for age, sex, PD duration, total UPDRS-III score, and presence of FOG. No significant associations (P[≥]0.14) were identified for total, arm, or neck rigidity. CONCLUSION: Lower limb rigidity is related to frequent falls in people with PD. Further investigation may be warranted into how parkinsonian rigidity could cause falls.\n\nFinancial Disclosures/Conflict of Interest concerning the research related to the manuscript: None\n\nFundingNIH K25HD086276, R01HD046922, R21HD075612, UL1TR002378, UL1TR000454; Department of Veterans Affairs R&D Service Career Development Awards E7108M and N0870W, Consolidated Anti-Aging Foundation, and the Sartain Lanier Family Foundation.

neuroscience↗

bioRxiv2018

Antagonist muscle activity during reactive balance responses is elevated in Parkinson’s disease and in balance impairment

BACKGROUND: Abnormal antagonist leg muscle activity could indicate increased muscle co-contraction and clarify mechanisms of balance impairments in Parkinsons disease (PD). Prior studies in carefully selected patients showed PD patients demonstrate earlier, longer, and larger antagonist muscle activation during reactive balance responses to perturbations. RESEARCH QUESTION: Here, we tested whether antagonist leg muscle activity was abnormal in a group of PD patients who were not selected for phenotype, and most of whom had volunteered for exercise-based rehabilitation. METHODS: We compared antagonist activation during reactive balance responses to multidirectional support-surface translation perturbations in 31 patients with mild-moderate PD (age 68{+/-}9; H&Y 1-3; UPDRS -III 32{+/-}10) and 13 matched individuals (age 65{+/-}9). We quantified modulation of muscle activity (i.e., the ability to activate and inhibit muscles appropriately according to the perturbation direction) using modulation indices (MI) derived from minimum and maximum EMG activation levels observed across perturbation directions. RESULTS: Antagonist leg muscle activity was abnormal in unselected PD patients compared to controls. Linear mixed models identified significant associations between impaired modulation and PD (P<0.05), PD severity (P<0.01), and balance ability (P<0.05), but not age (P=0.10). SIGNIFICANCE: Antagonist activity is increased during reactive balance responses in PD patients of varying phenotypes who are candidates for rehabilitation. Abnormal antagonist activity may contribute to balance impairments in PD and be a potential rehabilitation target or outcome measure.\n\nFunding SourcesThis work was supported by the National Institutes of Health (NIH) KL2 TR000455, K25 HD086276, R01 HD46922, R21 HD075612, TL1TR000456, and UL1 TR000424. The study sponsors had no role in study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.\n\nDeclaration of InterestConflicts of interest: None.\n\nAuthor ContributionsResearch project: Conception, JLM, LHT, MEH; Organization, JLM, KCL, LHT, MEH; Execution, JLM, KCL, LHT, MEH.\n\nStatistical Analysis: Design and Execution, JLM, KCL; Review and Critique, LHT, MEH. Manuscript Preparation: Writing of the first draft, KCL; Review and Critique: JLM, LHT, MEH.\n\nHighlights O_LIWe quantified abnormal antagonist muscle activation during balance in PD.\nC_LIO_LIAbnormalities were related to PD severity as well as to overall balance ability.\nC_LIO_LIAbnormalities were similar across PD phenotypes with and without tremor.\nC_LIO_LIBalance antagonist activation may be a useful rehabilitative outcome measure.\nC_LI

neuroscience↗

bioRxiv2017

The Influence of Parkinson’s Disease and Neurotypical Aging on Cognitive Performance Among Volunteers for an Exercise-based Rehabilitative Intervention

PURPOSETo determine the impact of aging versus combined aging and disease on cognition in older adults with and without Parkinsons disease (PD) who were volunteers for exercise based rehabilitation research.\n\nMETHODSWe used a multiple linear regression approach to analyze cognitive outcome measures of rehabilitation volunteers with and without PD.\n\nRESULTSSignificant associations were identified between increased age and decreased performance on 8 of the 14 outcomes analyzed after controlling for false discovery rate. Of those 8 outcomes, multivariate regression analyses demonstrated an effect of disease on performance in only 4/8. In all cases, PD was associated with superior, rather than decreased performance after controlling for age. Results were unaffected by sex and education. Post-hoc comparison with available age norms demonstrated that differences between PD and Non-PD volunteers could be primarily attributed to the Non-PD group substantially underperforming versus age norms.\n\nCONCLUSIONSIn rehabilitative exercise studies using volunteers, many cognitive domains decline with increasing age, consistent with previous neuropsychological studies without a rehabilitation component. However, older \"neurotypical\" volunteers may potentially underperform PD volunteers after controlling for age. This may be an important design consideration for rehabilitation studies with cognitive outcomes.\n\nIMPLICATIONS FOR REHABILITATIONO_LIAn increasing number of rehabilitation studies incorporate cognitive outcomes.\nC_LIO_LIWhether the overall cognitive profile of rehabilitation volunteers differs from that of neurotypical aging remains to be established.\nC_LIO_LIRehabilitation volunteers with Parkinsons disease may outperform putatively neurotypical volunteers after controlling for covariates.\nC_LIO_LICognitive impairments associated with PD in neuropsychological studies may not generalize to exercise rehabilitation volunteers.\nC_LI

neuroscience↗