A simplified in vivo near infrared spectroscopy
(NIRS) system for functional brain analysis and a protocol for the
study of visual evoked potentials in the human brain is presented.
A novel NIRS system bases on a simple photon counting technique
using a CW light source (laser diode at 780 nm), fibre optodes
delivering light to the subject and from the subject to detector, a
photomultiplier tube (PMT) for high infra-red (IR) response and
the 800 MHz Gated Photon Counter/multichannel scaler (MCS) for
data acquisition. A chequerboard stimulus was used to elicit a
response signal from the visual cortex. This photon signal arising
from the cortical systems of the brain was processed to detect
features indicative of the neural processing systems involved