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1.
Article in English | MEDLINE | ID: mdl-31231311

ABSTRACT

Purpose: Studies on long-term sustainability of low-carbohydrate approaches to treat diabetes are limited. We previously reported the effectiveness of a novel digitally-monitored continuous care intervention (CCI) including nutritional ketosis in improving weight, glycemic outcomes, lipid, and liver marker changes at 1 year. Here, we assess the effects of the CCI at 2 years. Materials and methods: An open label, non-randomized, controlled study with 262 and 87 participants with T2D were enrolled in the CCI and usual care (UC) groups, respectively. Primary outcomes were retention, glycemic control, and weight changes at 2 years. Secondary outcomes included changes in body composition, liver, cardiovascular, kidney, thyroid and inflammatory markers, diabetes medication use and disease status. Results: Reductions from baseline to 2 years in the CCI group resulting from intent-to-treat analyses included: HbA1c, fasting glucose, fasting insulin, weight, systolic blood pressure, diastolic blood pressure, triglycerides, and liver alanine transaminase, and HDL-C increased. Spine bone mineral density in the CCI group was unchanged. Use of any glycemic control medication (excluding metformin) among CCI participants declined (from 55.7 to 26.8%) including insulin (-62%) and sulfonylureas (-100%). The UC group had no changes in these parameters (except uric acid and anion gap) or diabetes medication use. There was also resolution of diabetes (reversal, 53.5%; remission, 17.6%) in the CCI group but not in UC. All the reported improvements had p < 0.00012. Conclusion: The CCI group sustained long-term beneficial effects on multiple clinical markers of diabetes and cardiometabolic health at 2 years while utilizing less medication. The intervention was also effective in the resolution of diabetes and visceral obesity with no adverse effect on bone health. Clinical Trial Registration: Clinicaltrials.gov NCT02519309.

2.
Sleep Med ; 55: 92-99, 2019 03.
Article in English | MEDLINE | ID: mdl-30772699

ABSTRACT

OBJECTIVE: Sleep disruption is frequently associated with type 2 diabetes (T2D) and hyperglycemia. We recently reported the effectiveness of a continuous care intervention (CCI) emphasizing nutritional ketosis for improving HbA1c, body weight and cardiovascular risk factors in T2D patients. The present study assessed the effect of this CCI approach on sleep quality using a subjective patient-reported sleep questionnaire. METHODS: A non-randomized, controlled longitudinal study; 262 T2D and 116 prediabetes patients enrolled in the CCI and 87 separately recruited T2D patients continued usual care (UC) treatment. Patients completed the Pittsburgh Sleep Quality Index (PSQI) questionnaire. A PSQI score of >5 (scale 0 to 21) was used to identify poor sleepers. RESULTS: Global sleep quality improved in the CCI T2D (p < 0.001) and prediabetes (p < 0.001) patients after one year of intervention. Subjective sleep quality (component 1), sleep disturbance (component 5) and daytime dysfunction (component 7), also showed improvements in the CCI T2D (p < 0.01 for sleep quality and sleep disturbance; and p < 0.001 for daytime dysfunction) and prediabetes patients (p < 0.001 for all three components); compared to the UC T2D group after one year. The proportion of patients with poor sleep quality was significantly reduced after one year of CCI (T2D; from 68.3% at baseline to 56.5% at one year, p = 0.001 and prediabetes; from 77.9% at baseline to 48.7% at one year, p < 0.001). CONCLUSION: This study demonstrates improved sleep quality as assessed by PSQI in patients with T2D and prediabetes undergoing CCI including nutritional ketosis but not in T2D patients receiving UC. The dietary intervention benefited both sleep quality and the severity of T2D symptoms suggesting that nutritional ketosis improves overall health via multiple mechanisms.


Subject(s)
Diabetes Mellitus, Type 2/diet therapy , Diabetes Mellitus, Type 2/diagnosis , Diet, Ketogenic/methods , Prediabetic State/diet therapy , Prediabetic State/diagnosis , Sleep Wake Disorders/diet therapy , Sleep Wake Disorders/diagnosis , Adult , Aged , Blood Glucose/metabolism , Diabetes Mellitus, Type 2/metabolism , Humans , Longitudinal Studies , Middle Aged , Prediabetic State/metabolism , Risk Factors , Sleep/physiology , Sleep Wake Disorders/metabolism , Young Adult
3.
BMJ Open ; 9(2): e023597, 2019 02 25.
Article in English | MEDLINE | ID: mdl-30803948

ABSTRACT

OBJECTIVE: One year of comprehensive continuous care intervention (CCI) through nutritional ketosis improves glycosylated haemoglobin(HbA1c), body weight and liver enzymes among patients with type 2 diabetes (T2D). Here, we report the effect of the CCI on surrogate scores of non-alcoholic fatty liver disease (NAFLD) and liver fibrosis. METHODS: This was a non-randomised longitudinal study, including adults with T2D who were self-enrolled to the CCI (n=262) or to receive usual care (UC, n=87) during 1 year. An NAFLD liver fat score (N-LFS) >-0.640 defined the presence of fatty liver. An NAFLD fibrosis score (NFS) of >0.675 identified subjects with advanced fibrosis. Changes in N-LFS and NFS at 1 year were the main endpoints. RESULTS: At baseline, NAFLD was present in 95% of patients in the CCI and 90% of patients in the UC. At 1 year, weight loss of ≥5% was achieved in 79% of patients in the CCI versus 19% of patients in UC (p<0.001). N-LFS mean score was reduced in the CCI group (-1.95±0.22, p<0.001), whereas it was not changed in the UC (0.47±0.41, p=0.26) (CCI vs UC, p<0.001). NFS was reduced in the CCI group (-0.65±0.06, p<0.001) compared with UC (0.26±0.11, p=0.02) (p<0.001 between two groups). In the CCI group, the percentage of individuals with a low probability of advanced fibrosis increased from 18% at baseline to 33% at 1 year (p<0.001). CONCLUSIONS: One year of a digitally supported CCI significantly improved surrogates of NAFLD and advanced fibrosis in patients with T2D. TRIAL REGISTRATION NUMBER: NCT02519309; Results.


Subject(s)
Diabetes Mellitus, Type 2/complications , Liver Cirrhosis/blood , Non-alcoholic Fatty Liver Disease/blood , Biomarkers/blood , Diabetes Mellitus, Type 2/diet therapy , Diet, High-Protein Low-Carbohydrate , Female , Humans , Liver Cirrhosis/diagnosis , Longitudinal Studies , Male , Middle Aged , Non-Randomized Controlled Trials as Topic , Non-alcoholic Fatty Liver Disease/diagnosis , Severity of Illness Index , Young Adult
4.
Cardiovasc Diabetol ; 17(1): 56, 2018 05 01.
Article in English | MEDLINE | ID: mdl-29712560

ABSTRACT

BACKGROUND: Cardiovascular disease (CVD) is a leading cause of death among adults with type 2 diabetes mellitus (T2D). We recently reported that glycemic control in patients with T2D can be significantly improved through a continuous care intervention (CCI) including nutritional ketosis. The purpose of this study was to examine CVD risk factors in this cohort. METHODS: We investigated CVD risk factors in patients with T2D who participated in a 1 year open label, non-randomized, controlled study. The CCI group (n = 262) received treatment from a health coach and medical provider. A usual care (UC) group (n = 87) was independently recruited to track customary T2D progression. Circulating biomarkers of cholesterol metabolism and inflammation, blood pressure (BP), carotid intima media thickness (cIMT), multi-factorial risk scores and medication use were examined. A significance level of P < 0.0019 ensured two-tailed significance at the 5% level when Bonferroni adjusted for multiple comparisons. RESULTS: The CCI group consisted of 262 participants (baseline mean (SD): age 54 (8) year, BMI 40.4 (8.8) kg m-2). Intention-to-treat analysis (% change) revealed the following at 1-year: total LDL-particles (LDL-P) (- 4.9%, P = 0.02), small LDL-P (- 20.8%, P = 1.2 × 10-12), LDL-P size (+ 1.1%, P = 6.0 × 10-10), ApoB (- 1.6%, P = 0.37), ApoA1 (+ 9.8%, P < 10-16), ApoB/ApoA1 ratio (- 9.5%, P = 1.9 × 10-7), triglyceride/HDL-C ratio (- 29.1%, P < 10-16), large VLDL-P (- 38.9%, P = 4.2 × 10-15), and LDL-C (+ 9.9%, P = 4.9 × 10-5). Additional effects were reductions in blood pressure, high sensitivity C-reactive protein, and white blood cell count (all P < 1 × 10-7) while cIMT was unchanged. The 10-year atherosclerotic cardiovascular disease (ASCVD) risk score decreased - 11.9% (P = 4.9 × 10-5). Antihypertensive medication use was discontinued in 11.4% of CCI participants (P = 5.3 × 10-5). The UC group of 87 participants [baseline mean (SD): age 52 (10) year, BMI 36.7 (7.2) kg m-2] showed no significant changes. After adjusting for baseline differences when comparing CCI and UC groups, significant improvements for the CCI group included small LDL-P, ApoA1, triglyceride/HDL-C ratio, HDL-C, hsCRP, and LP-IR score in addition to other biomarkers that were previously reported. The CCI group showed a greater rise in LDL-C. CONCLUSIONS: A continuous care treatment including nutritional ketosis in patients with T2D improved most biomarkers of CVD risk after 1 year. The increase in LDL-cholesterol appeared limited to the large LDL subfraction. LDL particle size increased, total LDL-P and ApoB were unchanged, and inflammation and blood pressure decreased. Trial registration Clinicaltrials.gov: NCT02519309. Registered 10 August 2015.


Subject(s)
Cardiovascular Diseases/prevention & control , Delivery of Health Care, Integrated , Diabetes Mellitus, Type 2/diet therapy , Diabetic Ketoacidosis/diet therapy , Diet, Carbohydrate-Restricted , Diet, Diabetic , Nutritional Status , 3-Hydroxybutyric Acid/blood , Adult , Biomarkers/blood , Blood Glucose/metabolism , Blood Pressure , Cardiovascular Diseases/blood , Cardiovascular Diseases/diagnosis , Cardiovascular Diseases/physiopathology , Combined Modality Therapy , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/diagnosis , Diabetes Mellitus, Type 2/physiopathology , Diabetic Ketoacidosis/blood , Diabetic Ketoacidosis/diagnosis , Diabetic Ketoacidosis/physiopathology , Diet, Carbohydrate-Restricted/adverse effects , Diet, Diabetic/adverse effects , Female , Humans , Hypoglycemic Agents/therapeutic use , Indiana , Inflammation Mediators/blood , Lipids/blood , Male , Middle Aged , Prospective Studies , Risk Factors , Time Factors , Treatment Outcome
6.
Diabetes Ther ; 9(2): 583-612, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29417495

ABSTRACT

INTRODUCTION: Carbohydrate restriction markedly improves glycemic control in patients with type 2 diabetes (T2D) but necessitates prompt medication changes. Therefore, we assessed the effectiveness and safety of a novel care model providing continuous remote care with medication management based on biometric feedback combined with the metabolic approach of nutritional ketosis for T2D management. METHODS: We conducted an open-label, non-randomized, controlled, before-and-after 1-year study of this continuous care intervention (CCI) and usual care (UC). Primary outcomes were glycosylated hemoglobin (HbA1c), weight, and medication use. Secondary outcomes included fasting serum glucose and insulin, HOMA-IR, blood lipids and lipoproteins, liver and kidney function markers, and high-sensitivity C-reactive protein (hsCRP). RESULTS: 349 adults with T2D enrolled: CCI: n = 262 [mean (SD); 54 (8) years, 116.5 (25.9) kg, 40.4 (8.8) kg m2, 92% obese, 88% prescribed T2D medication]; UC: n = 87 (52 (10) years, 105.6 (22.15) kg, 36.72 (7.26) kg m2, 82% obese, 87% prescribed T2D medication]. 218 participants (83%) remained enrolled in the CCI at 1 year. Intention-to-treat analysis of the CCI (mean ± SE) revealed HbA1c declined from 59.6 ± 1.0 to 45.2 ± 0.8 mmol mol-1 (7.6 ± 0.09% to 6.3 ± 0.07%, P < 1.0 × 10-16), weight declined 13.8 ± 0.71 kg (P < 1.0 × 10-16), and T2D medication prescription other than metformin declined from 56.9 ± 3.1% to 29.7 ± 3.0% (P < 1.0 × 10-16). Insulin therapy was reduced or eliminated in 94% of users; sulfonylureas were entirely eliminated in the CCI. No adverse events were attributed to the CCI. Additional CCI 1-year effects were HOMA-IR - 55% (P = 3.2 × 10-5), hsCRP - 39% (P < 1.0 × 10-16), triglycerides - 24% (P < 1.0 × 10-16), HDL-cholesterol + 18% (P < 1.0 × 10-16), and LDL-cholesterol + 10% (P = 5.1 × 10-5); serum creatinine and liver enzymes (ALT, AST, and ALP) declined (P ≤ 0.0001), and apolipoprotein B was unchanged (P = 0.37). UC participants had no significant changes in biomarkers or T2D medication prescription at 1 year. CONCLUSIONS: These results demonstrate that a novel metabolic and continuous remote care model can support adults with T2D to safely improve HbA1c, weight, and other biomarkers while reducing diabetes medication use. CLINICALTRIALS. GOV IDENTIFIER: NCT02519309. FUNDING: Virta Health Corp.


Treatments for type 2 diabetes (T2D) have improved, yet T2D and being overweight are still significant public health concerns. Blood sugar in patients with T2D can improve quickly when patients eat significantly fewer dietary carbohydrates. However, this demands careful medicine management by doctors, and patients need support and frequent contact with health providers to sustain this way of living. The purpose of this study was to evaluate if a new care model with very low dietary carbohydrate intake and continuous supervision by a health coach and doctor could safely lower HbA1c, weight and need for medicines after 1 year in adults with T2D. 262 adults with T2D volunteered to participate in this continuous care intervention (CCI) along with 87 adults with T2D receiving usual care (UC) from their doctors and diabetes education program. After 1 year, patients in the CCI, on average, lowered HbA1c from 7.6 to 6.3%, lost 12% of their body weight, and reduced diabetes medicine use. 94% of patients who were prescribed insulin reduced or stopped their insulin use, and sulfonylureas were eliminated in all patients. Participants in the UC group had no changes to HbA1c, weight or diabetes medicine use over the year. These changes in CCI participants happened safely while dyslipidemia and markers of inflammation and liver function improved. This suggests the novel care model studied here using dietary carbohydrate restriction and continuous remote care can safely support adults with T2D to lower HbA1c, weight, and medicine use.

7.
J Child Neurol ; 32(2): 161-169, 2017 02.
Article in English | MEDLINE | ID: mdl-27798370

ABSTRACT

Vibratory feedback can be a useful tool for rehabilitation. We examined its use in children with dystonia to understand how it affects muscle activity in a population that does not respond well to standard rehabilitation. We predicted scaled vibration (ie, vibration that was directly or inversely proportional to muscle activity) would increase use of the vibrated muscle because of task-relevant sensory information, whereas nonscaled vibration would not change muscle use. The study was conducted on 11 subjects with dystonia and 14 controls. Each subject underwent 4 different types of vibration on the more dystonic biceps muscle (or nondominant arm in controls) in a 1-dimensional, bimanual myocontrol task. Our results showed that only scaled vibratory feedback could bias muscle use without changing overall performance in children with dystonia. We believe there may be a role in rehabilitation for scaled vibratory feedback to retrain abnormal muscle patterns.


Subject(s)
Dystonia/physiopathology , Dystonia/rehabilitation , Feedback, Sensory , Motor Activity/physiology , Muscle, Skeletal/physiopathology , Vibration/therapeutic use , Adolescent , Arm/physiopathology , Child , Dystonic Disorders/physiopathology , Dystonic Disorders/rehabilitation , Female , Humans , Linear Models , Male , Young Adult
8.
PLoS One ; 10(10): e0139988, 2015.
Article in English | MEDLINE | ID: mdl-26447874

ABSTRACT

Fitts' Law describes the speed-accuracy trade-off of human movements, and it is an elegant strategy that compensates for random and uncontrollable noise in the motor system. The control strategy during targeted movements may also take into account the rewards or costs of any outcomes that may occur. The aim of this study was to test the hypothesis that movement time in Fitts' Law emerges not only from the accuracy constraints of the task, but also depends on the perceived cost of error for missing the targets. Subjects were asked to touch targets on an iPad® screen with different costs for missed targets. We manipulated the probability of error by comparing children with dystonia (who are characterized by increased intrinsic motor variability) to typically developing children. The results show a strong effect of the cost of error on the Fitts' Law relationship characterized by an increase in movement time as cost increased. In addition, we observed a greater sensitivity to increased cost for children with dystonia, and this behavior appears to minimize the average cost. The findings support a proposed mathematical model that explains how movement time in a Fitts-like task is related to perceived risk.


Subject(s)
Dystonia/physiopathology , Adolescent , Case-Control Studies , Child , Discrimination, Psychological , Dystonia/psychology , Female , Humans , Male , Motor Skills , Movement
9.
J Child Neurol ; 30(12): 1604-15, 2015 Oct.
Article in English | MEDLINE | ID: mdl-25792428

ABSTRACT

Abnormal motor cortex activity is common in dystonia. Cathodal transcranial direct current stimulation may alter cortical activity by decreasing excitability while anodal stimulation may increase motor learning. Previous results showed that a single session of cathodal transcranial direct current stimulation can improve symptoms in childhood dystonia. Here we performed a 5-day, sham-controlled, double-blind, crossover study, where we measured tracking and muscle overflow in a myocontrol-based task. We applied cathodal and anodal transcranial direct current stimulation (2 mA, 9 minutes per day). For cathodal transcranial direct current stimulation (7 participants), 3 subjects showed improvements whereas 2 showed worsening in overflow or tracking error. The effect size was small (about 1% of maximum voluntary contraction) and not clinically meaningful. For anodal transcranial direct current stimulation (6 participants), none showed improvement, whereas 5 showed worsening. Thus, multiday cathodal transcranial direct current stimulation reduced symptoms in some children but not to a clinically meaningful extent, whereas anodal transcranial direct current stimulation worsened symptoms. Our results do not support transcranial direct current stimulation as clinically viable for treating childhood dystonia.


Subject(s)
Dystonic Disorders/physiopathology , Dystonic Disorders/therapy , Motor Cortex/physiopathology , Transcranial Direct Current Stimulation/methods , Adolescent , Cerebral Palsy/physiopathology , Cerebral Palsy/therapy , Child , Cross-Over Studies , Double-Blind Method , Electromyography , Female , Hand/physiopathology , Humans , Male , Motor Activity/physiology , Muscle, Skeletal/physiopathology , Pilot Projects , Treatment Outcome , Young Adult
10.
Brain Stimul ; 7(5): 718-26, 2014.
Article in English | MEDLINE | ID: mdl-25088460

ABSTRACT

BACKGROUND: Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a treatment for severe childhood-onset dystonia. A common challenge for clinicians is determining which contacts of the DBS electrode to stimulate in order to provide maximum future benefit to the patient. OBJECTIVE: To characterize how the cortical responses to DBS relate to stimulation parameters (i.e. electrode contacts, voltage, and pulse width) and clinical outcomes. METHODS: We examined 11 patients with dystonia undergoing DBS therapy (9-21 years old when implanted). We varied the active contacts, voltage, and pulse width of the stimulating electrode and analyzed the deep-brain stimulator evoked potentials (DBSEPs) measured with electroencephalogram, and assessed symptoms with the Barry-Albright dystonia scale. Statistical tests included: Repeated measures ANOVA, Mann-Whitney U test and paired t-test. RESULTS: DBSEPs near sensorimotor areas were larger ipsilaterally than contralaterally (P = 0.007). The rate of DBSEP amplitude increase with respect to stimulator voltage (voltage gain) and pulse width (pulse width gain) varied across subjects and stimulating contacts. Voltage gains were significantly higher among patients who showed larger improvements with DBS (P = 0.038). Additionally, a within-subject comparison of all patients showed that voltage gains were higher for contacts chosen for chronic stimulation as compared to those that were not (P = 0.007). CONCLUSIONS: DBSEPs may be good predictors of therapeutic response to stimulation at different electrode contacts. Furthermore, effective DBS therapy appears to modulate sensorimotor cortex. These findings may help clinicians optimize stimulator programming and may eventually lead to improved targeting during implantation.


Subject(s)
Deep Brain Stimulation/methods , Dystonic Disorders/physiopathology , Dystonic Disorders/therapy , Electrodes, Implanted , Evoked Potentials/physiology , Adolescent , Child , Dystonic Disorders/diagnosis , Electroencephalography/methods , Female , Globus Pallidus/physiology , Humans , Male , Treatment Outcome , Young Adult
11.
Brain ; 137(Pt 7): 1931-44, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24812203

ABSTRACT

Cerebellar damage results in uncoordinated, variable and dysmetric movements known as ataxia. Here we show that we can reliably model single-joint reaching trajectories of patients (n = 10), reproduce patient-like deficits in the behaviour of controls (n = 11), and apply patient-specific compensations that improve reaching accuracy (P < 0.02). Our approach was motivated by the theory that the cerebellum is essential for updating and/or storing an internal dynamic model that relates motor commands to changes in body state (e.g. arm position and velocity). We hypothesized that cerebellar damage causes a mismatch between the brain's modelled dynamics and the actual body dynamics, resulting in ataxia. We used both behavioural and computational approaches to demonstrate that specific cerebellar patient deficits result from biased internal models. Our results strongly support the idea that an intact cerebellum is critical for maintaining accurate internal models of dynamics. Importantly, we demonstrate how subject-specific compensation can improve movement in cerebellar patients, who are notoriously unresponsive to treatment.


Subject(s)
Cerebellar Ataxia/pathology , Cerebellar Ataxia/physiopathology , Cerebellum/pathology , Cerebellum/physiopathology , Adult , Aged , Biomechanical Phenomena , Computer Simulation , Female , Functional Laterality/physiology , Humans , Male , Middle Aged , Models, Biological , Movement/physiology , Predictive Value of Tests , Psychomotor Performance
12.
J Neurosci ; 33(36): 14301-6, 2013 Sep 04.
Article in English | MEDLINE | ID: mdl-24005283

ABSTRACT

Because sensation is delayed, real-time movement control requires not just sensing, but also predicting limb position, a function hypothesized for the cerebellum. Such cerebellar predictions could contribute to perception of limb position (i.e., proprioception), particularly when a person actively moves the limb. Here we show that human cerebellar patients have proprioceptive deficits compared with controls during active movement, but not when the arm is moved passively. Furthermore, when healthy subjects move in a force field with unpredictable dynamics, they have active proprioceptive deficits similar to cerebellar patients. Therefore, muscle activity alone is likely insufficient to enhance proprioception and predictability (i.e., an internal model of the body and environment) is important for active movement to benefit proprioception. We conclude that cerebellar patients have an active proprioceptive deficit consistent with disrupted movement prediction rather than an inability to generally enhance peripheral proprioceptive signals during action and suggest that active proprioceptive deficits should be considered a fundamental cerebellar impairment of clinical importance.


Subject(s)
Cerebellum/physiopathology , Proprioception , Spinocerebellar Ataxias/physiopathology , Aged , Arm , Case-Control Studies , Female , Humans , Male , Middle Aged , Movement , Psychomotor Performance
13.
J Neurophysiol ; 109(8): 2228-41, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23390311

ABSTRACT

Damage to the cerebellum can cause significant problems in the coordination of voluntary arm movements. One prominent idea is that incoordination stems from an inability to predictively account for the complex mechanical interactions between the arm's several joints. Motivated by growing evidence that corrective feedback control shares important capabilities and neural substrates with feedforward control, we asked whether cerebellar damage impacts feedback stabilization of the multijoint arm appropriate for the arm's intersegmental dynamics. Specifically, we tested whether cerebellar dysfunction impacts the ability of posterior deltoid to incorporate elbow motion in its long-latency response (R2 = 45-75 ms and R3 = 75-100 ms after perturbation) to an unexpected torque perturbation. Healthy and cerebellar-damaged subjects were exposed to a selected pattern of shoulder-elbow displacements to probe the response pattern from this shoulder extensor muscle. The healthy elderly subjects expressed a long-latency response linked to both shoulder and elbow motion, including an increase/decrease in shoulder extensor activity with elbow flexion/extension. Critically, cerebellar-damaged subjects displayed the normal pattern of activity in the R3 period indicating an intact ability to rapidly integrate multijoint motion appropriate to the arm's intersegmental dynamics. However, cerebellar-damaged subjects had a lower magnitude of activity that was specific to the long-latency period (both R2 and R3) and a slightly delayed onset of multijoint sensitivity. Taken together, our results suggest that the basic motor pattern of the long-latency response is housed outside the cerebellum and is scaled by processes within the cerebellum.


Subject(s)
Cerebellar Ataxia/physiopathology , Joints/physiopathology , Muscle, Skeletal/physiopathology , Reaction Time , Adult , Aged , Case-Control Studies , Cerebellum , Feedback, Physiological , Humans , Joints/innervation , Middle Aged , Motion , Movement , Muscle, Skeletal/innervation , Torque , Upper Extremity/innervation , Upper Extremity/physiopathology
14.
J Neurophysiol ; 107(6): 1612-20, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22190620

ABSTRACT

Damage to the cerebellum causes characteristic movement abnormalities but is thought to have minimal impact on somatosensory perception. Traditional clinical assessments of patients with cerebellar lesions reveal no perceptual deficits despite the fact that the cerebellum receives substantial somatosensory information. Given that abnormalities have been reported in predicting the visual consequences of movement, we suspect that the cerebellum broadly participates in perception when motor output is required (i.e., active perception). Thus we hypothesize that cerebellar integrity is essential for somatosensory perception that requires motor activity, but not passive somatosensory perception. We compared the perceptual acuity of human cerebellar patients to that of healthy control subjects in several different somatosensory perception tasks with minimal visual information. We found that patients were worse at active force and stiffness discrimination but similar to control subjects with regard to passive cutaneous force detection, passive proprioceptive detection, and passive proprioceptive discrimination. Furthermore, the severity of movement symptoms as assessed by a clinical exam was positively correlated with impairment of active force perception. Notably, within the context of these perceptual tasks, control subjects and cerebellar patients displayed similar movement characteristics, and hence differing movement strategies are unlikely to underlie the differences in perception. Our results are consistent with the hypothesis that the cerebellum is vital to sensory prediction of self-generated movement and suggest a general role for the cerebellum in multiple forms of active perception.


Subject(s)
Cerebellar Diseases/physiopathology , Cerebellum/physiopathology , Discrimination, Psychological/physiology , Perception/physiology , Proprioception/physiology , Adult , Aged , Electromyography , Female , Humans , Male , Middle Aged , Muscle, Skeletal/physiopathology , Torque
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