Very slow potentials in the lateral geniculate complex and primary visual cortex during different illumination changes in freely moving rats.

ABSTRACT

Previous literature has shown different forms of very slow oscillatory phenomena (0-0.5 Hz) in the structures of brain visual system. It was demonstrated in aforementioned publications that this infraslow activity might be sensitive to the level of environmental illumination. This study was performed to test the hypothesis that extracellular very slow brain potential (VSBP) oscillations or fluctuations in lateral geniculate complex (LGC) and primary visual cortex (PVC) are responding specifically and concurrently to different illumination changes. Experiments were conducted on five albino rats with chronically implanted stereotaxic electrodes in LGC and PVC brain sites. Our results support the aforementioned suggestion and revealed significant and similar patterns of VSBP modification within a frequency domain of seconds (0.1-0.25 Hz) in both the LGC and PVC in response to darkness, illumination and photostimulation. It is also documented here that significant and similar changes of multisecond activity (0.02-0.04 Hz) occur in both investigated brain sites in response to photostimulation only. Based on these findings, we propose that a possible role for VSBP oscillations in the LGC and PVC should be strongly considered in the CNS mechanisms of visual information processing.