Measuring the haemodynamic responses elicited in the visual cortex from various spatial and temporal frequencies using NIRS

Thomas Bridge

Abstract


 

Previous research has found the optimum spatial and temporal frequency of a stimulus can elicit peak activation in the visual cortex. In this study eight participants looked at bullseye gratings with low and high spatial frequencies (0.5 & 3 c/deg) at varying temporal frequencies (1, 4, 8 & 30Hz). Their haemoglobin response in the visual cortex was recorded using Near Infra-red Spectroscopy (NIRS). Insignificant results were found in all measures, including oxygenated haemoglobin which reported F (1, 8, 5.63) = .75, p<.44. Trigonometric regression did illustrate increased visual activation when the bullseye grating was presented. It appears different frequencies can cause different haemodynamic response, but a larger sample and the elimination of disadvantages in NIRS is required to obtain significance.


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