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Impact of Retinal Stimulation on Neuromodulation
Published in Yu Chen, Babak Kateb, Neurophotonics and Brain Mapping, 2017
As they begin the journey to the visual cortex, the vast majority of signals (approximately 90%) leaving the optic nerve travel through the lateral geniculate nucleus (LGN) of the thalamus (Goldstein 2010) for further processing in the visual cortex as part of the central and peripheral eyesight pathways. Those signals lead toward attention on a selected target. Some signals branch off at the LGN to other subcortical structures involved with neurological circuitry and others modulating chemical circuitry as discussed in “Subcortical neurological circuitry” and “Subcortical chemical circuitry.” Some of these subcortical structures include the intergeniculate leaflet, the superior colliculus in the midbrain, the suprachiasmatic nucleus of the hypothalamus, the pineal gland, and the habenula (part of the limbic system connecting with motor circuitry). New research also has demonstrated a direct retinal pathway in humans to the brain’s pulvinar region (another portion of the thalamus) (Arcaro et al. 2015). Many of those locations send signals back to the LGN through feedback loops. Signals continue from the LGN through the optic radiations that traverse the parietal and temporal lobes.
Effects of Temporal Light Modulation on Cognitive Performance,Eye Movements, and Brain Function
Published in LEUKOS, 2023
Jennifer A. Veitch, Patricia Van Roon, Amedeo D’Angiulli, Arnold Wilkins, Brad Lehman, Greg J. Burns, E. Erhan Dikel
The dipole analysis showed two consistent patterns of results. First, the analysis showed the upper portion of the cerebellum (culmen and tuber of vermis) as the main source of activity for the entire ERP epoch, indicating cross-hemisphere communication. Concurrently, the analysis identified less intense but clear sources in the left hemisphere, notably, the pulvinar for congruent trials, and the caudate nucleus in the basal ganglia and the lateral dorsal nucleus of the thalamus for incongruent trials. Further analyses showed a consistent pattern of sources during the time intervals of early activation (between 60 and 340 ms after stimulus presentation) parallel to the generators for the overall epoch. For both congruent and incongruent trials, dipole activations were localized to the striate and extrastriate occipital and inferotemporal areas in the left and right hemisphere. (See Appendix D for the full results, including the tests that were not statistically significant, in Tables D18 to D21.)