Figure 2 | Scientific Reports

Figure 2

From: When light hurts: Comparative Morphometry of Human Brainstem in Traumatic Photalgia

Figure 2

Photalgia circuits. (1) Ganglion cells project light-related signaling to the olivary pretectal nucleus (OPN) that activate superior salivatory nucleus (SSN), which via pterygopalatine ganglion, causes ocular vasodilation and activation of ocular trigeminal afferents (orange) that are heavily expressed on blood vessels. These afferents, with cell bodies in the trigeminal ganglion, project to trigeminal nucleus caudalis, ventroposteromedial thalamus (VPM) and cortex. (2) Intrinsically photosensitive retinal ganglion cells (mRGCs) project directly to thalamic neurons (blue), which also receive intracranial nociceptive afferent signal from neurons in trigeminal ganglion and trigeminal nucleus caudalis of the brainstem (TNC; yellow). (3) VPM neurons, which fire in response to light and pain stimuli, project diffusely to sensory and association cortex (from12, with permission; promotional and commercial use of the material in print, digital or mobile device format is prohibited without the permission from the publisher Wolters Kluwer. Please contact healthpermissions@wolterskluwer.com for further information).