Abnormal Resting-State Functional Connectivity in Progressive Supranuclear Palsy and Corticobasal Syndrome

Abstract

BackgroundPathological and MRI-based evidence suggests that multiple brain structures are likely to be involved in functional disconnection between brain areas. Few studies have investigated resting-state functional connectivity (rsFC) in progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). In this study, we investigated within- and between-network rsFC abnormalities in these two conditions.MethodsTwenty patients with PSP, 11 patients with CBS, and 16 healthy subjects (HS) underwent a resting-state fMRI study. Resting-state networks (RSNs) were extracted to evaluate within- and between-network rsFC using the Melodic and FSLNets software packages.ResultsIncreased within-network rsFC was observed in both PSP and CBS patients, with a larger number of RSNs being involved in CBS. Within-network cerebellar rsFC positively correlated with mini-mental state examination scores in patients with PSP. Compared to healthy volunteers, PSP and CBS patients exhibit reduced functional connectivity between the lateral visual and auditory RSNs, with PSP patients additionally showing lower functional connectivity between the cerebellar and insular RSNs. Moreover, rsFC between the salience and executive-control RSNs was increased in patients with CBS compared to HS.ConclusionThis study provides evidence of functional brain reorganization in both PSP and CBS. Increased within-network rsFC could represent a higher degree of synchronization in damaged brain areas, while between-network rsFC abnormalities may mainly reflect degeneration of long-range white matter fibers.

Resting‐state Functional MRI in Parkinsonian Syndromes

“…Resting‐state functional connectivity studies in CBS patients are very few and quite inconsistent in their findings . Compared to healthy patients, CBS patients had increased connectivity in the default mode, executive‐control, sensorimotor, insular, and cerebellar networks and between the salience and executive‐control networks .…”

Non-Invasive Brain Stimulation in Dementia: A Complex Network Story

“…Similarly, posterior cortical atrophy, a condition characterized by predominant visuospatial dysfunctions [25] is associated with lower connectivity in the higher visual network [20]. Network abnormalities in Parkinson’s disease (PD) and corticobasal syndrome (CBS), two disorders of the motor spectrum, seem to involve the cerebello-thalamo-cortical and sensorimotor networks, respectively [14, 26]. While this evidence points to a clear correspondence between functional networks and syndrome-specific core symptoms, network dysfunction is not limited to a single circuit but generally involves several networks [17].…”

Corticobasal syndrome: neuroimaging and neurophysiological advances

“…Furthermore, functional MRI studies have disclosed marked differences in FC between patients with CBS and those with PSP. Functional disconnection of the thalamus with various cortical and cerebellar areas was evident in both syndromes, whilst FC of the dentate nucleus decreased in subcortical and prefrontal cortical areas in PSP but increased asymmetrically in the frontal cortex in CBS .…”

“…Besides structural MRI findings, several authors have investigated possible functional connectivity (FC) changes in patients with CBS using resting‐state functional MRI . Bharti et al .…”

“… showed that patients with CBS had increased within‐network FC than healthy subjects in the default mode, cerebellum, sensorimotor, executive‐control and insular networks suggesting global intrinsic hyperconnectivity amongst brain regions deputed to motor and cognitive/affective functions. Increased FC has been interpreted as a plasticity‐related shift in neuronal activity from atrophic to intact brain structures or as a direct consequence of disrupted neuronal activity caused by neurodegeneration . Upadhyay et al .…”