The Analysis Of Brain Activation And Functional Networks In Post-Stroke Cognitive Impairment Patients: An FNIRS Study

ObjectivePost-stroke cognitive impairment(PSCI),a frequent stroke complication,interferes with limb function recovery and dramatically reduces patients’ quality of life and survival time.As a result,one of the primary goals of the entire therapeutic management program should be to assess and restore cognitive function in stroke patients.The purpose of this study was to compare the brain functional connectivity and activation characteristics of patients with post-stroke cognitive impairment to healthy subjects in resting state and during verbal fluency task,with the goal of better understanding the pathological mechanisms of stroke-induced cognitive impairment and investigating the potential of fNIRS as an objective tool for identifying individuals at risk of stroke.MethodsThe study included 32 stroke patients who met the inclusion and exclusion criteria and were divided into two groups based on clinical presentation and Montreal Cognitive Assessment Scale scores: post-stroke cognitive impairment and non-PSCI(PSCI and NPSCI groups).As a control group,sixteen healthy older adults with no history of stroke were recruited(Healthy control group,HC group).All subjects underwent neuropsychological scale evaluation along with fNIRS measurements.The neuropsychological scales used included the Mini-mental State Examination(MMSE)and the Montreal Cognitive Assessment(MoCA),which evaluated each subject’s general cognitive functioning.fNIRS was used to collect hemodynamic data from subjects during a 6-minute resting state and a verbal fluency task(both phonological and semantic fluency tasks)in the bilateral prefrontal cortex(PFC),premotor cortex and supplementary motor area(PMC/SMA),and sensorimotor cortex(SMC).Observations were made to compare differences in functional connectivity between the three groups in the resting state,as well as brain activation characteristics between populations(between-group comparisons)and between tasks(within-group comparisons)under a verbal fluency task.Results1.A comparison of the individuals’ general demographic and clinical features revealed no statistical differences in age,gender,or education between the PSCI,NPSCI,and HC groups(P>0.05).There were no substantial differences in stroke type(ischaemic or hemorrhagic),stroke duration,stroke hemisphere,or lesion site between the PSCI and NPSCI groups(P> 0.05).The PSCI group’s MMSE and MoCA scores were significantly lower than those of the HC and NPSCI groups,with statistically significant differences(p<0.001).2.The comparison of resting-state functional connectivity in the PSCI,NPSCI,and HC groups revealed that interhemispheric functional connectivity and right intrahemispheric functional connectivity were lower in the PSCI group than in the HC group(p<0.05).Further analysis of the brain regions of interest revealed that PSCI patients had significantly reduced functional connectivity between S1.L-S1.R,S1.L-DLPFC.R,S1.RDLPFC.R,and S1.R-MPFC brain regions than HCs(p<0.05).However,there was no significant difference in functional connectivity between the PSCI and NPSCI groups(P>0.05).Furthermore,there was no significant change in functional connectivity based on oxyhaemoglobin and total haemoglobin concentrations(P>0.05).3.The comparison of brain activation during the verbal fluency task between the PSCI and HC groups revealed that: during the phonological fluency task,the activation of the right OFC was significantly higher in the PSCI group than in the HC group(P<0.05);during the semantic fluency task,there was no significant difference in the activation of the OFC brain area between the two groups(p>0.05);and for the HC and PSCI groups,the activation of OFC did not change substantially(P>0.05)between the phonological fluency task and the semantic fluency task.The activation of the MPFC during the two tasks did not differ significantly between the HC and PSCI groups(P>0.05);however,the activation of the MPFC was significantly greater in the HC group during the semantic fluency task than during the phonological fluency task(P<0.05);the activation of the MPFC during the two tasks did not differ significantly in the PSCI group(P>0.05).ConclusionWhen compared to the healthy population,patients with post-stroke cognitive impairment have abnormalities in functional brain connectivity at rest and brain region activation during verbal fluency tasks,and these differences may be potential biomarkers to assist in diagnosing PSCI.The current investigation discovered decreased inter-and right intra-hemispheric functional connectivity in PSCI patients,specifically between S1.L-S1.R,S1.L-DLPFC.R,S1.R-DLPFC.R,and S1.R-MPFC brain areas,and changes in these FCs may play a crucial role in the pathogenic mechanisms of PSCI.During the phonological fluency task,activation in the right OFC brain region was significantly higher in the PSCI group than in the HC group,which could be attributed to neural compensation and restructuring.The HC group activated the MPFC significantly more during the semantic fluency task than during the phonological fluency task,indicating differences in the anatomical and cognitive processes involved in the two tasks,whereas no such differences were observed in the PSCI group.fNIRS has unique benefits in studying the changes in cognitive function after stroke and its pathophysiological mechanisms;however,larger studies with more complex and refined analyses of poststroke cognitive impairment are required to gain a comprehensive understanding of the alterations and recovery of cognitive function in stroke patients.