Stimulus frequency affects c-fos expression in the rat visual system

We have characterised the c-fos expression patterns in various centers of t he visual pathway of adult rats monocularly stimulated either by continuous or flickering light at different frequencies. Results show different immun ocytochemical patterns in all centers studied, the geniculate lateral compl ex (LGC), superior colliculus (SC) and primary visual cortex (Oc1), dependi ng on the physical characteristics of the stimulus (blinking frequency and light wavelength). After stimulation of the left eye, the ipsilateral pathw ay presents a substantial density of immunoresponsive cells, which is great er than expected with respect to the number of fibers that project ipsilate rally from the retina to the LGC and the superficial layers of the SC. A su rprisingly high positive immunoresponsiveness is obtained in all cases with coherent light stimulation in the red spectrum (634 nm). (C) 2000 Elsevier Science B.V. All rights reserved.