Orienting system

The brain pathway that orients visual attention to a stimulus is referred to as the orienting system. There are two main types of visual orientations, covert (exogenous) which occurs when a salient environmental change causes a shift in attention and overt (endogenous) which occurs when the individual makes a conscious decision to orient attention to a stimuli[1] During a covert orientation of attention, the individual does not physically move, and during an overt orientation of attention the individual's eyes and head physically move in the direction of the stimulus.[2][1][3]

Information acquired through covert and overt visual orientations travels through the norepinephrine system, indirectly effecting the ventral visual pathway.[3] The four specific brain regions involved in this process are the frontal eye field, the temporoparietal junction, the pulvinar, and the superior colliculus.[3][2] The frontal eye field is involved in goal-driven eye movements and can inhibit stimulus driven eye movements.[2] The temporoparietal junction appears to be involved location-cueing tasks, and individuals with lesions in this area have difficulty with attentional reorienting.[2] The pulvinar is located posterior to the thalamus and its role in the orientating system is still being researched; however it is thought to be involved in covert orienting.[2] Finally, the superior colliculus provides information about the location of the stimuli to which attention is directed.[2]