visual encoding
the neural processes by which stimuli seen in the external world are converted into internal (mental) representations that can subsequently be processed and stored in memory. For example, when a person looks at a photograph, photoreceptors in the individual’s retina receive the visual sensory information and convey it to additional neurons, which in turn convey the information to populations of retinal ganglion cells. The cylindrical extensions (axons) of the retinal ganglion cells form the optic nerve, which projects to the lateral geniculate nucleus in the thalamus and the superior colliculus in the midbrain. The sensory input reaches visual areas in the cerebral cortex and ultimately the hippocampus within the medial temporal lobe, where—by mechanisms yet to be explained—it is analyzed and combined with input from the amygdala, entorhinal cortex, and other brain regions into a single abstract representation of the visual experience that is suitable for incorporation into short-term and possibly long-term memory. In other words, visual encoding may be conceptualized as a process intermediate to the extraction of meaning. Parallel neural conversion processes occur for stimuli that are heard (acoustic encoding), smelled (olfactory encoding), tasted (gustatory encoding), or felt (tactile encoding).