Investigation of Frontal Cortex, Motor Cortex and Systemic Haemodynamic Changes During Anagram Solving

We have previously reported changes in the concentrations of oxy-(delta[HbO2]) deoxy- (delta[HHb]) and total haemoglobin (delta[HbT] = delta[HbO2] + delta[HHb]) measured using near infrared spectroscopy (NIRS) over the frontal cortex (FC) during an anagram solving task. These changes were associated with a significant increase in both mean blood pressure (MBP) and heart rate (HR). The aim of this study was to investigate whether the changes in MBP previously recorded during an anagram solving task produces associated changes in scalp blood flow (flux) measured by laser Doppler and whether any changes are seen in NIRS haemodynamic measurements over a control region of the brain (motor cortex: MC). During the 4-Letter anagram task significant changes were observed in the delta[HbO2], delta[HHb] and delta[HbT] in both the frontal and motor cortex (n = 11, FC p < 0.01, MC p < 0.01). These changes were accompanied by significant changes in both MBP (n = 11, p < 0.01) and scalp flux (n = 9, p = 0.01). During the 7-Letter anagram task significant changes were observed in the delta[HbO2] and delta[HbT] (n = 11, FC p < 0.01, MC p < 0.01), which were accompanied by significant changes in both MBP (n = 11, p = 0.05) and flux (n = 9, p = 0.05). The task-related changes seen in MBP and flux in this study appear to contribute to the changes in the NIRS signals over both the activated and control regions of the cortex.