ABSTRACT
The superior colliculus is a laminated structure that consisted with superficial and deep layers in the roof of midbrain and the center of visual information and sensorimotor intergration. The deep layers of the mammalian superior colliculus are concerned with generation of eye movements. Serotonin is a neurotransmitter of the central nervous system and its binding sites can be classified into serotonin-1 receptor, serotonin-2 receptor and serotonin-3 receptor according to their pharmacological characteristics. The serotonin-2 receptors in the human brain presents in the motor cortex(area 4 of Brodmann) which role for the control of ocular motor activity and in the primary and secondary visual areas(areas 17 and 18 of Brodmann). Some of them presents in the limbic system role for the control of emotive activity, memory and other limbic functions. We performed this experiment to identify the anatomical distribution of the serotonergic nerve terminals in the superior colliculus of the rat by microscopicautography. It has been demonstrated that the serotonin-2 receptors of the superior colliculus are concerned with generation of saccade eye movements.