Abnormal Psychology

Understanding Psychological Disorders: The Neuropsychosocial Approach 47

of friends will be somewhat determined by your genes, and those friends will then

affect you in certain ways depending on their own characteristics.

3.Active interaction. Each of us actively seeks out some environments and avoids

others, and our genes infl uence which environments feel most comfortable to

us. For example, a person who is sensitive to environmental stimulation might

prefer spending a quiet evening at home curled up with a good book instead of

going to a loud, crowded party at a friend’s house.

The interactions between genes and the environment involve all of the factors

considered by the neuropsychosocial approach, and hence create complex feed-

back loops. Once the environment (including social factors, such as one’s choice of

friends) has been infl uenced by genes, the environment affects the genes (as well as

one’s knowledge, beliefs, attitudes, and so on).

Again, the import of these observations for psychological disorders is clear.

Genes can make a person at risk for a particular psychological disorder, but other

factors—psychological and social—can infl uence the expression of the genes. And

the specifi c psychological and social factors that affect a person arise, in part, from

that person’s genes (which affect, for example, aspects of his or her appearance).

Thus, even though genes may make some people vulnerable to specifi c kinds of men-

tal illness, the path from genes to illness is neither straight nor inevitable.

Key Concepts and Facts About Neurological Factors in Psychological Disorders

• The nervous system has two major parts: the central nervous
  system (CNS), which is composed of the brain and spinal cord,
  and the peripheral nervous system (PNS), which is composed
  of the sensory-somatic nervous system and the autonomic ner-
  vous system (ANS).


• The ANS controls many involuntary functions, such as those of
  the heart, blood vessels, and digestive tract. The ANS has two
  major components:
  
  
  • The sympathetic nervous system, which produces more
    adaptive bodily functioning in an emergency with the fi ght-or-
    fl ight response. As part of this response, the hypothalamic-
    pituitary-adrenal axis (HPA axis) manages the production of
    cortisol, which helps the muscles prepare for physical exer-
    tion. The HPA axis and high levels of cortisol are involved in
    depression and stress-related psychological disorders.
  
  
  • The parasympathetic nervous system, which typically brings
    the body back to its normal state after a fight-or-flight
    response. The parasympathetic system typically counteracts
    the effects of the sympathetic nervous system, and psycho-
    pathology may arise if it fails to do so effectively.
  
  
  
  


• The brain is divided into two hemispheres; the lobes of which
  (along with their key functions) are: occipital lobe (involved in
  vision), parietal lobe (involved in processing spatial informa-
  tion and self-awareness), temporal lobe (involved in processing
  auditory information, including speech, and memory), and fron-
  tal lobe (site of executive functioning).


• Subcortical (beneath the cortex) areas of importance (along
  with their key functions) are as follows:
  
  
  • The limbic system, which plays a key role in emotions and
    includes the hypothalamus (involved in controlling eating,
  
  
  
  

drinking, temperature, and emotions), the amygdala (central

to producing and perceiving strong emotions), and the hip-

pocampus (involved in storing new information in memory);

• The thalamus (involved in controlling sleep and maintaining
  attention);


• The nucleus accumbens (involved in registering reward and
  learning from experience);


• The basal ganglia (involved in automatic responses); and


• The cerebellum (involved in physical coordination and auto-
  matic motions).


• There are three types of neurons: sensory neurons, motor
  neurons, and interneurons (most neurons are interneurons).
  Neurons communicate with each other to create patterns of
  activation in brain circuits, which in turn are organized into large
  brain systems; these systems may be disrupted in cases of
  psychopathology.


• A neuron has a cell body, an axon that ends in terminal but-
  tons, and dendrites that receive signals from other neurons.
  The neuron is covered by a cell membrane that has channels
  that open when the neuron fi res.


• When a neuron fi res, neurotransmitters released from the
  terminal buttons travel across the synaptic cleft to receptors
  on the dendrite or cell body of another neuron. Neuromod-
  ulators may affect the functioning of neurotransmitters by
  altering events at the synapse.


• Neurotransmitter substances include dopamine (involved in re-
  ward, motivation, and executive functioning), serotonin (involved
  in mood, sleep, and motivation), acetylcholine (involved in memory
  and the fi ght-or-fl ight response), adrenaline and noradrenaline
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