0 0 2 ▁by ▁Sam er ▁H att ar , ▁David ▁B erson ▁and ▁colle agues , ▁where ▁they ▁were ▁shown ▁to ▁be ▁mel an ops in ▁express ing ▁gang l ion ▁cells ▁that ▁possessed ▁an ▁intr insic ▁light ▁response ▁and ▁project ed ▁to ▁a ▁number ▁of ▁brain ▁areas ▁involved ▁in ▁non - image - form ing ▁vision . ▁ ▁In ▁ 2 0 0 5 , ▁P anda , ▁M ely an , ▁Q iu , ▁and ▁colle agues ▁demonstrated ▁that ▁the ▁mel an ops in ▁phot op ig ment ▁was ▁the ▁phot otr ans du ction ▁p ig ment ▁in ▁gang l ion ▁cells . ▁Dennis ▁D ace y ▁and ▁colle agues ▁showed ▁in ▁a ▁species ▁of ▁Old ▁World ▁mon key ▁that ▁giant ▁gang l ion ▁cells ▁express ing ▁mel an ops in ▁project ed ▁to ▁the ▁later al ▁gen ic ulate ▁nucle us ▁( L GN ). ▁Pre viously ▁only ▁pro jections ▁to ▁the ▁mid bra in ▁( pre - te ct al ▁nucle us ) ▁and ▁hypoth al am us ▁( sup ra - ch ias m atic ▁nuc lei , ▁SC N ) ▁had ▁been ▁shown . ▁However , ▁a ▁visual ▁role ▁for ▁the ▁re ceptor ▁was ▁still ▁uns us pected ▁and ▁un pro ven . ▁ ▁Research ▁ ▁Research ▁in ▁humans ▁▁ ▁Att empt s ▁were ▁made ▁to ▁h unt ▁down ▁the ▁re ceptor ▁in ▁humans , ▁but ▁humans ▁pos ed ▁special ▁challeng es ▁and ▁demanded ▁a ▁new ▁model . ▁Un like ▁in ▁other ▁animals , ▁research