Showing papers by "Scott Peltier published in 2012"

Resting state cortico-cerebellar functional connectivity networks: a comparison of anatomical and self-organizing map approaches.

Abstract: The cerebellum plays a role in a wide variety of complex behaviors. In order to better understand the role of the cerebellum in human behavior, it is important to know how this structure interacts with cortical and other subcortical regions of the brain. To date, several studies have investigated the cerebellum using resting-state functional connectivity magnetic resonance imaging (fcMRI; Buckner et al., 2011; Krienen & Buckner, 2009; O’Reilly et al., 2009). However, none of this work has taken an anatomically-driven approach. Furthermore, though detailed maps of cerebral cortex and cerebellum networks have been proposed using different network solutions based on the cerebral cortex (Buckner et al., 2011), it remains unknown whether or not an anatomical lobular breakdown best encompasses the networks of the cerebellum. Here, we used fcMRI to create an anatomically-driven cerebellar connectivity atlas. Timecourses were extracted from the lobules of the right hemisphere and vermis. We found distinct networks for the individual lobules with a clear division into “motor” and “non-motor” regions. We also used a self-organizing map algorithm to parcellate the cerebellum. This allowed us to investigate redundancy and independence of the anatomically identified cerebellar networks. We found that while anatomical boundaries in the anterior cerebellum provide functional subdivisions of a larger motor grouping defined using our self-organizing map algorithm, in the posterior cerebellum, the lobules were made up of sub-regions associated with distinct functional networks. Together, our results indicate that the lobular boundaries of the human cerebellum are not indicative of functional boundaries, though anatomical divisions can be useful, as is the case of the anterior cerebellum. Additionally, driving the analyses from the cerebellum is key to determining the complete picture of functional connectivity within the structure.

Altered functional connectivity between the insula and the cingulate cortex in patients with temporomandibular disorder: A pilot study

Abstract: Background.- Among the most common chronic pain conditions, yet poorly understood, are temporomandibular disorders (TMDs), with a prevalence estimate of 3-15% for Western populations. Although it is increasingly acknowledged that central nervous system mechanisms contribute to pain amplification and chronicity in TMDs, further research is needed to unravel neural correlates that might abet the development of chronic pain. Objective.- The insular cortex (IC) and cingulate cortex (CC) are both critically involved in the experience of pain. The current study sought specifically to investigate IC-CC functional connectivity in TMD patients and healthy controls (HCs), both during resting state and during the application of a painful stimulus. Methods.- Eight patients with TMD, and 8 age- and sex-matched HCs were enrolled in the present study. Functional magnetic resonance imaging data during resting state and during the performance of a pressure pain stimulus to the temple were acquired. Predefined seed regions were placed in the IC (anterior and posterior insular cortices) and the extracted signal was correlated with brain activity throughout the whole brain. Specifically, we were interested whether TMD patients and HCs would show differences in IC-CC connectivity, both during resting state and during the application of a painful stimulus to the face. Results.- As a main finding, functional connectivity analyses revealed an increased functional connectivity between the left anterior IC and pregenual anterior cingulate cortex (ACC) in TMD patients, during both resting state and applied pressure pain. Within the patient group, there was a negative correlation between the anterior IC-ACC connectivity and clinical pain intensity as measured by a visual analog scale. Conclusions.- Since the pregenual region of the ACC is critically involved in antinociception, we hypothesize that an increase in anterior IC-ACC connectivity is indicative of an adaptation of the pain modulatory system early in the chronification process. (Less)

L-DOPA changes spontaneous low-frequency BOLD signal oscillations in Parkinson's disease: a resting state fMRI study

Abstract: Analysis of the amplitude of low frequency BOLD signal fluctuations (ALFF) in the resting state has recently been used to study the dynamics of intrinsic neural activity. Several studies have also suggested its potential as a biomarker for neuropsychiatric disease. In the current study, we quantified ALFF to determine changes in intrinsic neural oscillations in patients with Parkinson's disease (PD) on and off L-DOPA. Twenty-four PD patients and 24 healthy age-matched controls participated in the study. PD patients underwent two resting state fMRI sessions, either ON a controlled dose of L-DOPA or following a placebo pill (OFF). Control participants underwent one test session. We found that there was increased amplitude of low frequency BOLD signal oscillations for PD patients OFF L-DOPA in the primary and secondary motor areas, and in the middle and medial prefrontal cortices. L-DOPA significantly reduced the amplitude of low frequency oscillations within these regions. The degree of ALFF in the premotor cortex predicted patients' motor performance as measured by the Grooved Pegboard task, such that greater ALFF was associated with poorer performance. These results are in line with the pathophysiology of PD, which shows changes in neural oscillations. Thus, frequency domain analyses of resting state BOLD fMRI signals may provide a useful means to study the pathophysiology of PD and the physiology of the brain's dopaminergic pathways.

Abstract S6-3: Neurocognitive impact in adjuvant chemotherapy for breast cancer linked to fatigue: A Prospective functional MRI study

Abstract: Background: Our previous research showed evidence of compromised cognitive function prior to adjuvant chemotherapy for breast cancer, with fatigue as a contributory factor. Fatigue is a common symptom reported by women treated for breast cancer, yet its association with neurocognitive function has not been systematically examined. In this prospective study, we examined possible alterations in neurocognitive responses, namely, working memory, from pre- to post- adjuvant treatment during functional magnetic resonance imaging (fMRI) and further investigated whether early fatigue might be linked to cognitive alterations over time. Methods: Women treated with either adjuvant chemotherapy (anthracyline-based combination regimen, n=29) or radiotherapy (n = 37) for localized breast cancer (Stages 0-IIIa) and age-matched healthy controls (n = 32) were enrolled. Participants performed a verbal working memory task (VWMT) with varying levels of demand for cognitive control during fMRI scanning and provided self-reports of fatigue (FACT-F) at two time points coincident with pre- and one-month post chemotherapy assessments. Imaging data were analyzed with general linear models using SPM5; comparative statistics were used to determine group differences, and correlational analyses addressed relationships of fatigue and neurocognitive measures. Findings: The chemotherapy group reported significantly greater severity of fatigue (p Discussion: Neurocognitive alterations during a working memory task and greater fatigue were evident before any adjuvant chemotherapy for breast cancer. Notably, functional alterations in working memory processes were evident with fMRI before adjuvant chemotherapy and predicted severity of post-treatment fatigue. Importantly, across all participants, greater fatigue over time was correlated with reduced cognitive performance. Taken together, these findings indicate that pre-treatment neurocognitive compromise and fatigue are key contributors to the cognitive impact often attributed solely to chemotherapy. Early therapeutic interventions targeting fatigue may improve cognitive function and reduce the distress of “chemo brain” throughout the course of adjuvant treatment. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S6-3.

Brief communication Differential relationships between transcallosal structural and functional connectivity in young and older adults

Abstract: Numerous studies have identified age differences in brain structure and function that correlate with declines in motor performance. While these investigations have typically focused on activity in isolated regions of the brain, resting state functional connectivity magnetic resonance imaging (MRI) and diffusion tensor imaging allow for more integrative assessments of spatially disparate neural networks. The novel contribution of the current study is to combine both resting state functional connectivity and diffusion tensor imaging to examine motor corticocortical circuits in young and older adults. We find that relatively greater functional connectivity between the primary motor cortices was strongly associated with decreased structural connectivity and poorer motor performance solely in older adults. We suggest that greater functional connectivity in older adults may be reflective of a release from the normally predominantly inhibitory interhemispheric communication associated with the primary motor cortices.