Distinct Functional and Macrostructural Brain Changes in Parkinson's Disease and Multiple System Atrophy →

ABSTRACT: Parkinson's disease (PD) and the parkinsonian variant of multiple system atrophy (MSAp) are neurodegenerative disorders that can be difficult to differentiate clinically. This study provides the first characterization of the patterns of task-related functional magnetic resonance imaging (fMRI) changes across the whole brain in MSAp. We used fMRI during a precision grip force task and also performed voxel-based morphometry (VBM) on T1-weighted images in MSAp patients, PD patients, and healthy controls. All groups were matched on age, and the patient groups had comparable motor symptom durations and severities. There were three main findings. First, MSAp and PD had reduced fMRI activation in motor control areas, including the basal ganglia, thalamus, insula, primary sensorimotor and prefrontal cortices, and cerebellum compared with controls. Second, there were no activation differences among the disease groups in the basal ganglia, thalamus, insula, or primary sensorimotor cortices, but PD had more extensive activation deficits throughout the cerebrum compared with MSAp and controls. Third, VBM revealed reduced volume in the basal ganglia, middle and inferior cerebellar peduncles, pons, and throughout the cerebrum in MSAp compared with controls and PD, and additionally throughout the cerebellar cortex and vermis in MSAp compared with controls. Collectively, these results provide the first evidence that fMRI activation is abnormal in the basal ganglia, cerebellum, and cerebrum in MSAp, and that a key distinguishing feature between MSAp and PD is the extensive and widespread volume loss throughout the brain in MSAp.

Human Brain Mapping 03/2015; DOI:10.1002/hbm.22694  · 5.97 Impact Factor

Subthalamic nucleus-sensorimotor cortex functional connectivity in de novo and moderate Parkinson's disease →

ABSTRACT: Previous research has indicated increased functional connectivity between subthalamic nucleus (STN) and sensorimotor cortex in off-medication Parkinson's disease (PD) compared with control subjects. It is not clear if the increase in functional connectivity between STN and sensorimotor cortex occurs in de novo PD, which is before patients begin dopamine therapy. Resting-state functional magnetic resonance imaging was carried out in 20 de novo (drug naïve) patients with PD (Hoehn and Yahr stage: I-II), 19 patients with moderate PD (Hoehn and Yahr stage: II-III), and 19 healthy controls. The functional con-nectivity analysis in de novo and moderate PD patients focused on the connectivity of the more affected STN and the sensorimotor cortex. Using resting-state functional connectivity analysis, we provide new evidence that people with de novo PD and off-medicated moderate PD have increased functional con-nectivity between the more affected STN and different regions within the sensorimotor cortex. The overlapping sensorimotor cortex found in both de novo and moderate PD had functional connectivity values that correlated positively with the Unified Parkinson's Disease Rating Scale part III. This key finding suggests that changes in functional connectivity between STN and sensorimotor cortex occur early in the disease following diagnosis and before dopamine therapy.

Neurobiology of Aging 07/2014; 36(1). DOI:10.1016/j.neurobiolaging.2014.07.004  · 5.01 Impact Factor

Functional Brain Activity Relates to 0-3 and 3-8 Hz Force Oscillations in Essential Tremor →

ABSTRACT: It is well-established that during goal-directed motor tasks, patients with essential tremor have increased oscillations in the 0-3 and 3-8 Hz bands. It remains unclear if these increased oscillations relate to activity in specific brain regions. This study used task-based functional magnetic resonance imaging to compare the brain activity associated with oscillations in grip force output between patients with essential tremor, patients with Parkinson's disease who had clinically evident tremor, and healthy controls. The findings demonstrate that patients with essential tremor have increased brain activity in the motor cortex and supplementary motor area compared with controls, and this activity correlated positively with 3-8 Hz force oscillations. Brain activity in cerebellar lobules I-V was reduced in essential tremor compared with controls and correlated negatively with 0-3 Hz force oscillations. Widespread differences in brain activity were observed between essential tremor and Parkinson's disease. Using functional connectivity analyses during the task evidenced reduced cerebellar-cortical functional connectivity in patients with essential tremor compared with controls and Parkinson's disease. This study provides new evidence that in essential tremor 3-8 Hz force oscillations relate to hyperactivity in motor cortex, 0-3 Hz force oscillations relate to the hypoactivity in the cerebellum, and cerebellar-cortical functional connectivity is impaired.

Cerebral Cortex 06/2014; 25(11). DOI:10.1093/cercor/bhu142  · 8.67 Impact Factor

Differences in Brain Activation Between Tremor- and Nontremor-Dominant Parkinson Disease →

ABSTRACT: OBJECTIVE To compare differences in functional brain activity between tremor- and nontremor-dominant subtypes of Parkinson disease (PD) using functional magnetic resonance imaging. DESIGN In our study, patients with tremor-dominant PD and those with nontremor-dominant PD performed a grip task, and the results obtained were compared using voxelwise analysis. Areas of the brain that were significantly different were then examined using a region-of-interest analysis to compare these patients with healthy controls. Voxel-based morphometry was used to determine macroscopic differences insz gray and white matter volume between patient groups. SETTING University-affiliated research institution. PARTICIPANTS A total of 20 drug-naive patients with PD (10 with tremor-dominant PD and 10 with nontremor-dominant PD) and a total of 20 healthy controls. MAIN OUTCOME MEASURES Blood oxygenation level-dependent activation and percent signal change. RESULTS Robust findings across both voxelwise and region-of-interest analyses showed that, compared with patients with tremor-dominant PD, patients with nontremor-dominant PD had reduced activation in the ipsilateral dorsolateral prefrontal cortex, the globus pallidus interna, and the globus pallidus externa. Region-of-interest analyses confirmed that patients with nontremor-dominant PD had reduced activity in the ipsilateral dorsolateral prefrontal cortex, the globus pallidus interna, and the globus pallidus externa compared with patients with tremor-dominant PD and healthy controls. Patients with tremor-dominant PD had increased activity in the contralateral dorsolateral prefrontal cortex compared with patients with nontremor-dominant PD and healthy controls. These results could not be explained by differences in gray or white matter volume. CONCLUSIONS Reduced brain activity occurs in the prefrontal cortex and globus pallidus of patients with nontremor-dominant PD compared with both patients with tremor-dominant PD and healthy controls, which suggests that functional magnetic resonance imaging is a promising technique to understand differences in brain activation between subtypes of PD.

JAMA Neurology 01/2013; 70(1):100-6. DOI:10.1001/jamaneurol.2013.582· 7.27 Impact Factor

Specific cerebellar regions are related to force amplitude and rate of force development →

ABSTRACT: The human cerebellum has been implicated in the control of a wide variety of motor control parameters, such as force amplitude, movement extent, and movement velocity. These parameters often covary in both movement and isometric force production tasks, so it is difficult to resolve whether specific regions of the cerebellum relate to specific parameters. In order to address this issue, the current study used two experiments and SUIT normalization to determine whether BOLD activation in the cerebellum scales with the amplitude or rate of change of isometric force production or both. In the first experiment, subjects produced isometric pinch-grip force over a range of force amplitudes without any constraints on the rate of force development. In the second experiment, subjects varied the rate of force production, but the target force amplitude remained constant. The data demonstrate that BOLD activation in separate sub-areas of cerebellar regions lobule VI and Crus I/II scales with both force amplitude and force rate. In addition, BOLD activation in cerebellar lobule V and vermis VI was specific to force amplitude, whereas BOLD activation in lobule VIIb was specific to force rate. Overall, cerebellar activity related to force amplitude was located superior and medial, whereas activity related to force rate was inferior and lateral. These findings suggest that specific circuitry in the cerebellum may be dedicated to specific motor control parameters such as force amplitude and force rate.

NeuroImage 09/2011; 59(2):1647-56. DOI:10.1016/j.neuroimage.2011.09.019· 6.25 Impact Factor