Neurons are the smallest units of the nervous system. Each neuron contains a cell nucleus (the cell body) surrounded by dendrites and axons. Dendrites receive messages from other neurons and send them back along axons. A single neuron can communicate with thousands of others through these connections. When a signal passes down an axon it triggers a release of chemicals called neurotransmitters into the synaptic cleft separating the two neurons. Neurotransmitters transmit nerve impulses from one neuron to another. Eighty percent of these neurons reside in the brain itself making them available to countless different pathways. The brain’s various functions—sensory experience, coordination and movement, ‘higher functions”, such as perception, comprehension, judgment, reasoning, and planning—each show particular patterns of neural activation across different areas of the cerebral cortex. Only recently have brain imaging techniques allowed neuroscientists the ability to examine these activities in great detail and it has become clear that we still have much to learn about the complexities of our brains.
Mind and brain
In many cultures around this world, there is the view that humans have a soul that exists independently of the physical body. For Greek philosophers, the soul was also viewed as the seat of our reasoning abilities - what we would call our minds today. While Aristotle...
