Abstract
Purpose::
Understand how the brain processes visual information related to visually-guided mating behavior.
Methods::
We used in situ preparation to record responses of the single brain cell to stimulation of the eye. We removed intestine, heart and legs, and put the brain with optic nerve connection to eyes onto the perfusion chamber inserted in the body. We recorded the brain cells response from the second visual ganglion, medulla, with a glass microelectrode filled with fluorescent dye, Lucifer yellow. We classified the cells with the response to objects and a natural scene movie displayed on the LCD monitor put in front of the lateral eye.
Results::
We detected three types of visually responsive cells in the Limulus brain. 1: contrast cell that responds to the contrast of objects. The receptive fields are located throughout the visual field. 2: binocular cells that respond to illumination of either or both eyes. Their receptive fields were symmetrically mapped on both sides of the body. 3: motor control cell that sends nerve fibers toward the motor ganglia innervating the leg muscle.
Conclusions::
The three cells may have important roles in the brain processing information related to the visually-guided mating behavior. The response of contrast cells is consistent with known behavior in which a horseshoe crab approaches female-like objects having either negative or positive contrast which respect to the surround. Such contrast cells may provide the first step of visual processing. With the symmetrical arrangement of receptive fields on the both sides of the body, binocular cells may locate females by subtracting information from two eyes. The motor control cell in the medulla indicates that this region of the brain directory innervates the motor system controlling location and this is the final step of visual processing for mate detection.
Keywords: electrophysiology: non-clinical • receptive fields