Certain drugs produce psychological effects by increasing or decreasing the quantity of neurotransmitters at the synapse. Other drugs work at the receptor sites, blocking the receptors or interfering with the removal or reabsorption of the neurotransmitters. Drugs that block the dopamine receptors, for example, reduce the symptoms of schizophrenia.

The brain has plasticity, that is, it can be physically and chemically altered by experience. In a pioneering study of the influence of the environment on the brain, researchers found that rats that had been raised in a stimulating environment had more synaptic connections than rats that had been raised in cages that offered them no opportunities to explore or to manipulate objects.

Select Page 1) Neurons, The Messengers 2) The Neural Impulse 3) The Synapse 5) The Central Nervous System 6) The Brain 7) Hemispheric Specialization 8) The Limbic System 9) The Spinal Cord 10) Tools for Studying the Nervous System 11) The Peripheral Nervous System 12) The Endocrine System 13) Behavior Genetics and Our Human Heritage 14) Genetics and Behavior