THE NERVOUS SYSTEM [ WORKING TOGETHER/SEEING THE BALL ( WHAT IS PLEASURE? )]

WORKING TOGETHER

How do all of these systems central and peripheral, somatic and autonomic and receptors work together in the symphony of the brain? From simple actions to complex ones, these systems must work in concert.

Consider the “simple” act of catching a ball. It’s an amazingly complex process that requires some basic anatomical structures and neural circuitry before it can be attempted. Obviously, most animals cannot toss an object. Nearly all lack hands with fingers and opposable thumbs, as well as the dexterity that has developed in human beings, across millennia of evolution, through the growth of increasingly complex neural circuits in the cerebellum and cerebral cortex. Thanks to evolution providing the basic tools of manual dexterity and the expansion of specialized brain functions such as those children develop when learning how to throw a ball, adults have basic skills ready to be activated when a ball comes their way.

SEEING THE BALL

The simplified version goes like this. When someone throws you a ball, photoreceptors in your eyes register the action and send it along afferent nerve fibers to specific portions of the frontal lobes of the cerebral cortex. Parallel processing of various sensations including the motion of the pitching arm, the path of the ball as it travels through the air, and its speed occurs within milliseconds. The cortex registers the perception “The ball has been thrown” and works with the cerebellum to calculate its likely point of arrival.

WHAT IS PLEASURE?

“OUR ENTIRE psychical activity is bent upon procuring pleasure and avoiding pain,” Sigmund Freud said in 1920. More than a century earlier, British philosopher Jeremy Bentham had a similar idea: What humans seek to do is maximize pleasure and minimize pain.

But what is pleasure? Bentham equated it with happiness. Freud named things (especially sex) that make us feel good. It’s not an abstract argument for neurochemists . So called recreational drugs affect the centers of the brain that register pleasure. How ironic that Freud championed cocaine as a treatment for neural disorders.

If it’s thrown particularly hard, say, and right at your head, the autonomic nervous system registers the action as a possible threat, sends out efferent signals that release a chemical soup of neurotransmitters, and may prompt you to duck. But if the ball arrives as an ordinary pitch you’ve experienced a thousand times, the motor areas of the cortex, which control voluntary movement, work with the cerebellum and basal ganglia to move your gloved hand to the right place for the catch.