Journal Article


S Coyle
T. Ward
C. Markham
R. O'Neill
S Lebid



visual cortex evoked potentials visual brain stimulation time measurements frequency domain multi functional electronic engineering optical systems

Multi-timescale measurements of brain responses in visual cortex during functional stimulation using time-resolved spectroscopy (2005)

Abstract Studies of neurovascular coupling (hemodynamic changes and neuronal activation) in the visual cortex using a timedomain single photon counting system have been undertaken. The system operates in near infrared (NIR) range of spectrum and allows functional brain monitoring to be done non-invasively. The detection system employs a photomultiplier and multi-channel scaler to detect and record emerging photons with sub-microsecond resolution (the effective collection time per curve point is ~ 200 ns). Localisation of the visual evoked potentials in the brain was done using knowledge obtained from electroencephalographic (EEG) studies and previous frequency-domain optical NIR spectroscopic systems. The well-known approach of visual stimulation of the human brain, which consists of an alternating black and white checkerboard pattern used previously for the EEG study of neural responses, is applied here. The checkerboard pattern is synchronized with the multi-channel scaler system and allows the analysis of time variation in back-scattered light, at different stimulation frequencies. Slow hemodynamic changes in the human brain due to Hb- HbO2 changes in the blood flow were observed, which is evidence of the system’s capability to monitor these changes. Monocular visual tests were undertaken and compared with those done with an EEG system. In some subjects a fast optical response on a time scale commensurate with the neural activity associated with the visual cortex was detected. Future work will concentrate on improved experimental protocols and apparatus to confirm the existence of this important physiological signal.
Collections Ireland -> Maynooth University -> Subject = Science & Engineering: Electronic Engineering
Ireland -> Maynooth University -> Subject = Science & Engineering
Ireland -> Maynooth University -> Type = Article
Ireland -> Maynooth University -> Academic Unit = Faculty of Science and Engineering
Ireland -> Maynooth University -> Academic Unit = Faculty of Science and Engineering: Electronic Engineering
Ireland -> Maynooth University -> Status = Published
Ireland -> Maynooth University -> Open Access DRIVERset

Full list of authors on original publication

S Coyle, T. Ward, C. Markham, R. O'Neill, S Lebid

Experts in our system

Shirley Coyle
Dublin City University
Total Publications: 86
Tomas Ward
Maynooth University
Total Publications: 189
Charles Markham
Maynooth University
Total Publications: 64