________________
Perceiving--Touching/Pain, Seeing and Hearing
Since the sense-organ of touch is also the instrument of experiencing pain, all one-sensed organisms must experience pain also. Pain and pleasure are the results of the vedniya or feeling-producing karman which has two sub-species (a) pleasure-producing and (b) pain or suffering-producing. These feelings are experienced by all organisms from one-sensed to five-sensed. We shall discuss the mechanism and programs of touching, seeing, caring as well as experiencing pain in this chapter. 1. Programs for Perceiving
Without a continua) flow of information from specialized sense receptors, the brain would be cut off, not only from the external environment but also from an awareness of the body's internal states. Out of the traditional 'five senses', sense of touch, which includes pain, is a 'near sense' wbile seeing and hearing are 'distance senses' equipped with distance receptors. Though thousands of sensory messages are received by the brain every second, only those which are important are 'perceived' wbile the rest are ignored. Thus, there is a remarkable distinction between sensation and perception. The messages or signals may come from events far away as in seeing, or at the surface of the body as by touching, or actually within it as when feeling pain. 2. The Cerebral Cortex and Perception
The cerebral cortex is an immense folded sheet of layers of nerve-cells arranged in columns. The nerve-fibres bringing signals from the sense-organs, via tbe thalamus, enter the sheet from the inside. They are arranged in a regular pattern or map, which exactly reproduces every xoint of the receptive surface of the body, in the correct relations with its reighbors. Thus there are cortical maps for vision, for hearing, and for ouch. It is interesting tbat there are no such detailed maps for smell or aste, which do not have the same power to detect 'shape', at least in man. t is the cortex that asks meaningful questions and so dictates the whole xerceptual process through its connections with the mid-brain. But more nteresting problem is to find out bow the cortex uses the messages it gets rom the sense-organs to answer its questions and ask more questions. This is the serial process that we call perception.
