Fig 2.

Neurochemistry of vision. Input from the retina (1) reaches the lateral geniculate nucleus of the thalamus (2). This structure and the adjacent pulvinar of the thalamus (3), an accessory visual structure that may act to filter out eye-movement “noise,” act as a junction between retino-geniculo-calcarine and ascending brain stem circuits, receiving inhibitory serotonergic input from the raphe nuclei (6) and excitatory cholinergic input from the pedunculopontine and parabrachial nuclei (7). The reticular nucleus of the thalamus (8) also provides inhibitory GABAergic innervation to the geniculate, which is itself modulated by the same ascending cholinergic and serotonergic input. The glutamatergic excitatory circuits from the geniculate to the occipital cortex (5) are also modulated by the superior colliculus (4). Reproduced with permission from Dr. Ramon Mocellin.