NIRS Measurement of Hemodynamic Evoked Responses in the Primary Sensorimotor Cortex

Abstract

To investigate the relationship between neuronal activity and hemodynamics, we carried out a near-infrared spectroscopy (NIRS) study to measure the regional changes of hemoglobin concentration associated with cortical activation in the human sensorimotor cortex (SMI) to both voluntary and nonvoluntary tasks. We measured the hemodynamic evoked responses to voluntary finger movement and nonvoluntary electrical stimulation applied on the fingers (thumb and ring finger, respectively). Measurements were performed on 6 healthy right-handed volunteers using block paradigms and we analyzed both the spatial/temporal features and the magnitude of the optical signal induced by cerebral activation during these protocols. We constantly observed an increase in the cerebral concentration of oxygenated hemoglobin at the cortical side contralateral to the stimulated side. Our findings are in agreement with results in positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and EEG (Electroencephalogram).

Task complexity relates to activation of cortical motor areas during uni- and bimanual performance: A functional NIRS study

“…HHb concentration increases or decreases after stimulus onset. Similar discrepancies have been described further as partial volume effect (Boas et al, 2001, Strangman et al, 2002b, Huppert et al, 2006, Xu et al, 2007. Partial volume effect is the effect wherein insufficient image resolution leads to a mixing of different tissue types.…”

Cortical activation change induced by neuromuscular electrical stimulation during hand movements: a functional NIRS study

“…In addition, several studies have reported that NMES has a direct effect on the cortical activation [16-19]. On the other hand, some studies have reported changes of cortical activation with functional recovery of the hemiparetic hand after long-term intensive treatment by NEMS [20,21]. However, little is known about the short-term effect on the changes of cortical activation during motor performance after application of NMES.…”

“…Several functional neuroimaging techniques, such as functional MRI, magnetoencephalography, Positron Emission Tomography, and functional near infrared spectroscopy (fNIRS) are available for use in studies of brain activation induced by NMES [18,20-23]. Among these techniques, fNIRS, a new emerging distinguished optical instrument, based on the intrinsic optical absorption of blood, enables noninvasive measurement of regional relative hemodynamic responses associated with cortical activation [24-28].…”

“…Compared with other functional neuroimaging techniques, fNIRS system has certain advantages, including lower price and portability [27]. In particular, due to less sensitivity to electrical current and metallic effect of the NMES machine, fNIRS could be appropriate for research on brain activation patterns by NMES [17,20,24-26]. …”