Structural Damage and Functional Reorganization in Ipsilesional M1 in Well-Recovered Patients With Subcortical Stroke

Abstract

Background and Purpose-Both structural atrophy and functional reorganization of the primary motor cortex (M1) have been reported in patients with subcortical infarctions affecting the motor pathway. However, the relationship between structural impairment and functional reorganization in M1 remains unclear. Methods-Twenty-six patients exhibiting significant recovery after subcortical infarctions were investigated using multimodal MRI techniques. Structural impairment was assessed via cortical thickness, and functional reorganization was analyzed using task-evoked activation, amplitude of low-frequency fluctuation, and resting-state functional connectivity. Results-Compared with healthy controls, patients with stroke exhibited reduced cortical thickness in the ipsilesional M1; however, this region exhibited increased task-evoked activation, amplitude of low-frequency fluctuation, and resting-state functional connectivity in these patients. Patients with stroke demonstrated increased task-evoked activation in another ipsilesional M1 region, in which increased amplitude of low-frequency fluctuation and resting-state functional connectivity were observed. The structural and functional changes in M1 were located selectively in the ipsilesional hemisphere. Conclusions-We

Structural and functional hyperconnectivity within the sensorimotor system in xenomelia

“…However, if structural hyperconnectivity has the same potential to break down a network's functioning as has a structurally hypoconnected network, then functional hyperconnectivity might be interpreted as a sign of functional compensation in response to the structural network impairments. Exactly this pattern of connectivity dissociation has been reported previously in healthy subjects notably in fronto‐parietal networks (Eickhoff et al., 2010) and in pathological conditions such as major and late life depression (de Kwaasteniet et al., 2013; Steffens, Taylor, Denny, Bergman, & Wang, 2011; Wu et al., 2011) and stroke (Zhang et al., 2014). Alternatively, however, an increase in functional connectivity may reflect a pathological loss of inhibitory neural activity within structurally damaged cortical networks as has been shown in patients suffering from amyotrophic lateral sclerosis (Douaud, Filippini, Knight, Talbot, & Turner, 2011).…”

Enhancing Rehabilitative Therapies with Vagus Nerve Stimulation

“…Rehabilitation can yield some functional gains, but recovery is often incomplete and the majority of patients are left with chronic disability [52][53][54]. Motor networks in surviving peri-infarct regions, as well as the undamaged contralateral homotopic cortex and subcortical structures, demonstrate significant reorganization after stroke [55][56][57]. Plasticity in these areas is believed to support functional recovery [58].…”

Changes in functional connectivity correlate with behavioral gains in stroke patients after therapy using a brain-computer interface device

“…With regard to stroke rehabilitation, the understanding of the FC changes that result from stroke and those observed during the recovery process is a growing area of interest that may be used to guide future therapeutic approaches (James et al, 2009; Grefkes and Fink, 2011; Westlake and Nagarajan, 2011; Jiang et al, 2013; Varkuti et al, 2013). One study of subcortical stroke survivors has shown reorganization in the ipsilesional motor cortex to be strongly associated with post stroke recovery (Zhang et al, 2014). However, another study of subcortical stroke patients found different patterns of increased resting-state FC in the sensorimotor network in those with right hemisphere strokes compared to those with strokes in the left hemisphere (Wang et al, 2014).…”