Jevin W Zhang1,2, Condon Lau1,2, Matthew M. Cheung1,2, Kyle Xing1,2, Iris Y. Zhou1,2, Kevin C. Chan1,2, Ed X. Wu1,2
1Laboratory of Biomedical Imaging & Signal Processing, the University of Hong Kong, Hong Kong, Hong Kong SAR, China, People's Republic of; 2Department of Electrical & Electronic Engineering, the University of Hong Kong, Hong Kong, Hong Kong SAR, China, People's Republic of
In rats, the superior colliculus (SC) is the main destination for retinal ganglion cells and is an important subcortical structure for vision. Its light intensity dependence has not been extensively studied with functional imaging. BOLD fMRI is used to measure the SCs hemodynamic response, in Sprague-Dawley rats, to visual stimulation at five intensity levels (4.2x10-3 to 0.74W/m2). Significant responses are observed at all intensity levels. Less of the SC responds to 4.2x10-3W/m2 stimulation than to higher intensity stimuli (p<0.05). The response amplitude during 4.2x10-3W/m2 stimulation is also significantly lower than during 7.6x10-2 and 0.23W/m2 stimulation (p<0.05).