Visual system iii dorsal pathway: introduction to the dorsal pathway. The dorsal pathway processes depth and motion. Components of the dorsal pathway are v1, v2, v3, middle temporal (mt), medial superior temporal (mst), intraparietal regions (lat. , vent. , med. , ant. Lesions in the human parietal cortex can cause. Attentional hemineglect: neglect of contralateral space, also manifested in memory. Constructional apraxia: inability to reproduce complex objects. V1, v2: lower level processing of stereoscopic vision. 3d depth perception is achieved by stereopsis: there is a slight disparity between the images on the two retinas. Both v1 and v2 are tuned to binocular image disparity and motion direction. Mt cells respond to motion direction and speed, as well as to binocular disparity. Mt receptive fields are larger than in lower levels. Mt columns are organized in smooth gradients of direction preference and stereoscopic depth. Microstimulation of mt cells can bias perception of motion direction and depth.