The Mind's Machine: Chapter 12

Psychopathology

Schizophrenia

A mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions.

Positive symptoms

Abnormal behavioral states that have been gained; includes hallucinations, delusions, and excited motor behavior.

Negative symptoms

Abnormalities resulting from the loss of normal functions; includes slow and impoverished thought and speech, emotional and social withdrawal, or blunted affect.

Heritability of schizophrenia

The mode of inheritance of schizophrenia does not involve a single recessive or dominant gene, multiple genes play a role. The more closely related a person is to someone with schizophrenia, the greater are that person’s chances of also developing schizophrenia.

Structural changes in brain & schizophrenia

Most people with schizophrenia have enlarged cerebral ventricles, especially the lateral ventricles. These must come at an expense of brain tissue. People with schizophrenia differ from controls in the structure and functional activity of the corpus callosum.

Hypofrontality

Hypothesis that the frontal lobes are underactive in people with schizophrenia.

Lobotomy

Surgical separation of a portion of the frontal lobes from the rest of the brain. Often used as a treatment for schizophrenia in the 1930s. Performed on some 40,000 people in the U.S. alone.

Dopamine hypothesis

People with schizophrenia have an excess of either dopamine release or dopamine receptors.

Typical (“first-generation”) neuroleptics

D2 receptor antagonists. The clinically effective dose of a 1st gen neuroleptic can be predicted from its affinity for D2 receptors.

Atypical (“second-generation”) neuroleptics

Developed to reduce motor side effects. These drugs generally have only moderate affinity for D2 dopamine receptors that are the principal site of action for 1st gen neuroleptics. Have the highest affinity for other transmitter receptors.

PCP

Phencyclidine. Found to be a potent psychotomimetic, or produces phenomena strongly resembling both the positive and negative symptoms of schizophrenia. Users often experience auditory hallucinations, strange depersonalization, and disorientation, and may become violent as a result of delusions. Acts as a NMDA receptor antagonist, blocking central calcium channel, preventing glutamate from having its usual effects.

Ketamine

NMDA receptor antagonist. Used as an anesthetic and a treatment for depression and pain.

Glutamate hypothesis

Schizophrenia results from an underactivation of glutamate receptors, which might account for the reduced activity in the frontal cortex.

Depression

Characterized by a combination of unhappy mood, loss of interests, reduced energy, changes in appetite and sleep patterns, and loss of pleasure in most things. Difficulty in concentration and restless agitation are common. The person may dwell on thoughts of death or contemplate suicide.

Neural activity (regions) & depression

When depressed people are compared with control individuals, increased activation in the amygdala is especially evident during emotional processing, and increased activity in the frontal lobes is evident during more cognitively demanding tasks. Decreased activity is evident in the parietal and posterior temporal cortex and in the anterior cingulate cortex (systems that have been implicated in attention)

Electroconvulsive shock therapy

Intentional induction of large-scale seizure. Can rapidly reverse severe depression.

rTMS

Repetitive transcranial magnetic stimulation. Electromagnetic coil delivers magnetic pulses that stimulate nerve cells in the region of your brain involved in mood control and depression.

MAO inhibitors

First antidepressants were these. Causes monoamine transmitters to accumulate higher levels in synapses. Researchers proposed depressed people don’t get enough stimulation at monoamine synapses.

Tricyclics

Second generation of antidepressants. Inhibit the reuptake of monoamines, which boosts synaptic activity.

SSRIs

Selective serotonin reuptake inhibitors. Act to increase synaptic serotonin levels in the brain.

Bipolar disorder

Characterized by periods of depression alternating with periods of excessively expansive mood (mania) that includes sustained overactivity, talkativeness, strange grandiosity, and increased energy. The rate at which the alternation occurs varies between individuals.

Lithium

Element that relieves symptoms of bipolar disorder in humans.

Anxiety disorders

Includes phobic disorders, panic disorder, and generalized anxiety disorder. Strong genetic contribution to each, and distinctive underlying neurobiological predispositions to the development of anxiety disorders.

Benzodiazepines

Class of drugs used to treat anxiety. Interact with binding sites that are part of GABA receptors (especially GABA4) where they act as noncompetitive agonists. When present, GABA produces a markedly enhanced hyperpolarization. Reduce excitability of postsynaptic neurons.