Cortical haemodynamic response measured by functional near infrared spectroscopy during fine motor task performance in patients with mild cognitive impairment

To investigate differences in cortical haemodynamic responses and the relationship between cognitive and motor functions in patients with MCI and healthy older adults during fine motor task performance using fNIRS.

Seventy participants (30 patients with MCI, 40 HC) completed the nine hole peg test (NHPT) while fNIRS signals were recorded from the bilateral somatosensory cortex (SMC), premotor cortex (PMC), frontal area (FA) and Visual cortex (V). Additionally, all participants underwent comprehensive neuropsychological assessments, including the montreal cognitive assessment (MoCA), the auditory verbal learning test-Huashan version (AVLT-H), the shape trail test-a-Chinese version (STT-A-C), and the shape trail test-b-Chinese version (STT-B-C).

Compared to HC, patients with MCI exhibited significantly reduced haemodynamic responses in the right SMC, bilateral PMC, and FA during the NHPT task (all p 0.05, FDR corrected). Superior fine motor performance was positively correlated with higher AVLT-Recall scores and shorter reaction times on STT_A_C and STT_B_C (all p 0.05, FDR corrected). Additionally, higher haemodynamic activity in the right FA and SMC was significantly associated with shorter reaction times on STT_A_C and STT_B_C (all p 0.05, FDR corrected). Furthermore, we conducted mediation analyses to investigate the effect of mean oxy-haemoglobin on the relationship between cognitive functions and NHPT. The results revealed that the mean oxy-haemoglobin of the right FA mediated the relationship between STT_A_C and NHPT performance, while the mean oxy-haemoglobin of the left PMC mediated the association between STT_B_C and NHPT outcomes (all p 0.05).

These findings indicate that cognitive impairments in memory and executive function in patients with MCI are associated with declines in fine motor control and reduced cerebral haemodynamic responses in the right FA and SMC. Furthermore, the oxy-haemoglobin levels in the right FA and left PMC were found to mediate the relationship between executive function and motor performance. 

The haemodynamic responses in the right FA, SMC, and left PMC may serve as potential neural biomarkers for identifying motor-cognitive dysfunction, particularly in the context of fine motor tasks.