Chapter summary imageCan understanding the brain help us understand human thought and behaviour?

WHAT CHARACTERISTICS DESCRIBE THE HUMAN BRAIN?

  • The human brain has three major characteristics: integration, sophistication, and adaptability.

HOW IS THE NERVOUS SYSTEM ORGANIZED?

  • The nervous system consists of the central nervous system (the brain and the spinal cord) and the peripheral nervous system (the neurons and nerves that serve every other part of the body).
  • The peripheral nervous system is divided into the somatic nervous system, which registers stimuli and regulates conscious actions, and the autonomic nervous system, which controls involuntary actions.
  • Within the autonomic nervous system, the sympathetic system stimulates organs and responds to stress, and the parasympathetic system calms the organs and maintains normal functioning.

HOW DOES THE NERVOUS SYSTEM OPERATE AT THE CELLULAR LEVEL?

  • The brain is made up of neurons and glial cells. Neurons are communication cells that receive, process, and pass on neural signals.
  • Glia support and insulate neurons.
  • Neuron signalling is an all-or-nothing event. When the number of positive inputs exceeds a certain threshold, the neuron fires an action potential—an electrochemical signal that travels down the axon. In the synapse, neurotransmitters pass on information to the next neuron or gland.
  • Communication within neurons is electrical. Communication between neurons is chemical.

WHAT ARE THE DIFFERENT PARTS OF THE HUMAN BRAIN, AND WHAT ROLE DOES EACH PART PLAY?

  • The brainstem is connected to the spinal cord and houses the structures that maintain basic life functions.
  • The limbic system regulates emotion, motivation, and social and emotional learning.
  • The cerebral cortex performs most information processing. It has four lobes: The occipital lobe processes visual information; the temporal lobe handles auditory input and language; the parietal lobe interprets sensory information; and the frontal lobe coordinates memory, reasoning, problem solving, social behaviour, language, and movement.
  • The brain is divided into two hemispheres that are connected by the corpus callosum. Language is most commonly processed in the left hemisphere. Spatial information is most commonly processed in the right hemisphere. Cutting the corpus callosum prevents communication between the right and left hemispheres.