How Do Biological Theorists Explain Abnormal Behavior?
Biological theorists view abnormal behavior as an illness brought about by malfunctioning parts of the organism. They typically point to problems in brain anatomy or brain chemistry as the cause of the problem.
- Brain Anatomy and Abnormal Behavior -
The brain is made up of approximately 100 billion nerve cells, called neurons, and thousands of billions of support cells, called glia. Within the brain, large groups of neurons form distinct brain areas, one of which is known as the cerebrum. The cerebrum includes the cortex, corpus callosum, basal ganglia, hippocampus, and amygdala. Each of these brain regions control important functions:
• The cortex is the outer layer of the brain.
• The corpus callosum connects the brain’s two cerebral hemispheres.
• The basal ganglia plays a crucial role in planning and producing movement.
• The hippocampus helps regulate emotions and memory.
• The amygdala plays a key role in emotional memory.
Researchers have found links between certain psychological disorders and problems in specific areas of the brain. One disorder is Huntington’s disease, which is a disorder marked by violent emotional outbursts, memory loss, suicidal thinking, involuntary body movements, and absurd beliefs. It has been traced to a loss of cells in the basal ganglia and cortex.
- Brain Chemistry and Abnormal Behavior -
Psychological disorders can also be related to problems in the transmission of messages from neuron to neuron. Information is communicated throughout the brain in the form of electrical impulses that travel from one neuron to one or more others. An impulse is received by a neuron’s dendrites, which then travels down the neuron’s axon, until it is finally transmitted through the nerve ending at the end of the axon to the dendrites of other neurons.
• Dendrites are antenna-like extensions located at one end of the neuron.
• The axon is a long fiber extending from the neuron’s body.
Since the neuron’s don’t actually touch each other, you may wonder how the messages get from the nerve ending of one neuron to the dendrites of another. A tiny space called the synapse is what separates one neuron from the next. When an electrical impulse reaches a neuron’s ending, the nerve ending is stimulated to release a chemical known as a neurotransmitter, which travels across the synaptic space to receptors on the dendrites of the neighboring neurons. After binding to the receiving neuron’s receptors, the neurotransmitters can either have an excitatory or inhibitory response. Some neurotransmitters give a message to the neurons to “fire” or trigger their own electrical impulse, while others tell receiving neurons to stop all firing.
Studies have shown that abnormal activity by some neurotransmitters can lead to certain mental disorders. For example, depression is linked to low activity of the neurotransmitters serotonin and norepinephrine.
Abnormal chemical activity in the endocrine system has also been shown to be related to mental disorders. Endocrine glands, located throughout the body, work with neurons to control vital activities such as growth, reproduction, sexual activity, heart rate, body temperature, energy, and stress response. The glands release chemicals known as hormones into the bloodstream that propel body organs into action. During times of stress, for example, the adrenal glands, located on top of the kidneys, secrete the hormone cortisol to help the body deal with the stress. Abnormal secretion of this chemical has been linked to anxiety and mood disorders.
(Comer, R. J. (2004). Abnormal psychology (8th ed.). New York: Worth.)