Differential cortical hemodynamics during standard and reversed visually guided navigation: An fNIRS-based investigation

Abstract

Visuospatial perception, which is based on the comprehension of objects and space, requires spatial attention to the surrounding environment. Stimulus-related elements that affect visuospatial tasks include object geometry, familiarity, complexity, and picture plane versus depth rotation. The dorsal stream pathway from the visual cortex, which is implicated in spatial processing, reflects the spatial component needed to orient the focus of attention to the location of the expected target stimulus. It is activated during spatial localization. While processing spatial information, visual, somatosensory, and auditory information is received from the inferotemporal cortex, medial and superior parietal cortices, and transverse temporal gyrus, and is projected directly toward the prefrontal cortex, which includes the premotor cortex. In this study 10 volunteers performed standard and reverse visually guided weight-shifting training tasks. This study aimed to investigate the hemodynamic response of the parietal to occipital cortex during these tasks using a 41-channel functional near-infrared spectroscopy system. During the standard navigation task, the right supramarginal gyrus showed a significant increase in oxy-hemoglobin (HbO) and total-hemoglobin (HbT) values. In contrast, the reverse navigation task showed significant increments in HbO values in the right angular gyrus (AG) and left somatosensory association cortex (SAC) and in HbT values in the left SAC and both AG. Thus, according to our results, spatial processing based on reversal may be different. Moreover, a difference in the amount of oxygen was observed. Further studies are required to understand the activated neural mechanisms when sensory inputs differ during spatial information processing.