Neuroanatomical substrates underlying contrast sensitivity

Contrast sensitivity (CS), a measurement of the ability to discriminate an object from its background, is an essential domain of visual functions (1,2). CS decline or impairment indicates one’s disability to discern an object in low contrast, which has been related to poor performance in driving (3,4), face recognition (5), real-world mobility tasks (6,7), postural stability (8), reading processes (9,10), and other functions of everyday life (11). Aging or lesions in the eye (including the retina) as well as in thalamic or cortical locations are usually responsible for this decline or impairment (12,13). Previous studies in animals have suggested that lesions in medial posterior thalamus and striate cortex significantly depress CS (14,15). However, whether neuroanatomical substrates are underlying CS in humans is largely unknown. Furthermore, there is evidence that CS deficits are associated with several neurological and psychiatric disorders, such as Alzheimer’s disease (16,17), Parkinson’s disease (18) and depression (19). Thus, a better understanding of the neural mechanism of CS may have some clinical significance in understanding these brain diseases