Activation of the visual cortex imaged by 24-channel near-infrared spectroscopy

Abstract

Near-infrared spectroscopy (NIRS) is a noninvasive technique for continuous monitoring of the amounts of total hemoglobin (total-Hb), oxygenated hemoglobin, (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb). The purpose of the present study was to demonstrate the utility of NIRS in functional imaging of the human visual cortex. A new NIRS imaging system enabled measurements from 24 scalp locations covering a 9 cm sq area. Topographic images were obtained from interpolations of the concentration changes between measurement points. Five healthy subjects between 25 and 49 years of age were investigated. After a resting baseline period of 50 s, the subjects were exposed to a visual stimulus for 20 s, followed by a 50 s resting period in a dimly lit, sound attenuating room. The visual stimulus was a circular, black and white, alternating checkerboard. In four of five subjects the visual cortex was the most activated area during visual stimulation. This is the first reported use of a NIRS-imaging system for assessing hemodynamic changes in the human visual cortex. The typical hemodynamic changes expected were observed; the total-Hb and oxy-Hb increased just after the start of stimulation and plateaued after 10 s of the stimulation period.

Hemodynamic response to visual stimulation in newborn infants using functional near‐infrared spectroscopy

“…In fMRI and NIRS studies different types of stimuli were used for visual brain function in adults and infants [Born et al, 1998;Colier et al, 2001;Meek et al, 1998;Takahashi et al, 2000;Villringer et al, 1993]. In adults the size of the activated area depends on the type of the stimulus which was maximal for the checkerboard paradigm, but the physiological effect responsible for the observed stimulus dependence could not be clarified [Kruger et al, 1998].…”

Noninvasive optical imaging in the visual cortex in young infants

“…Various stimuli were used in previous NIRS studies on visual brain function in adults, including picture observation [Villringer et al, 1993], flashing light at a frequency of 8 Hz [Kato et al, 1993], a multicolored moving dodecahedron [Wenzel et al, 1996], a green-red checkerboard reversing at a frequency of 10 Hz [Heekeren et al, 1999], a checkerboard [Takahashi et al, 2000], and a hemi-field green-white checkerboard reversing at a frequency of 8 Hz [Colier et al, 2001]. Results of those studies showed that the typical response of visual cortex activation in adults is an increase in [oxyHb] and a slight decrease in [deoxyHb].…”

A Functional Near-infrared Spectroscopy Study to Detect Activation of Somatosensory Cortex by Peripheral Nerve Stimulation

“…The technique has also been designated as optical topography, diffuse optical tomography, and near-infrared imaging [6]. Recent studies have used the well-studied observation that regional cerebral blood flow increases in response to a stimulus or cognitive task and have applied NIRS in functional imaging and cortical brain mapping [7][8][9][10][11]. Although the spatial resolution of NIRS is not high, it offers distinctive advantages over functional magnetic resonance imaging (fMRI) including its portability (e.g., at the bedside), ability to separate oxy-, deoxy-, and total-Hb, and non-invasive nature while maintaining comparable spatial and temporal resolution [6].…”