Schizophrenia and the Dopamine Hypothesis Vocabulary

A collection of vocabulary terms and definitions regarding the biological explanations and symptoms of schizophrenia, as discussed in the lecture notes.

Schizophrenia Hallucinations

Sensory experiences where a person sees or hears something that is not there, such as voices telling them they are useless.

Schizophrenia Delusions

Firmly held beliefs that are not true, such as the paranoid belief that the government is spying on one's movements.

Schizophrenia Negative Symptoms

Behaviors such as poor motivation, social withdrawal, lack of self-care (skipping showers), and poverty of speech.

Synaptic Transmission

The process by which one neuron communicates with another via an electrical impulse known as an action potential that crosses the synaptic gap.

Neurotransmitters

Chemical messengers contained in synaptic vesicles at the axon terminal that transmit signals across the synaptic gap to receptor sites on a post-synaptic cell.

Dopamine

An excitatory neurotransmitter associated with pleasure, reward centers, movement regulation, and emotional responses.

Hyperdopaminergia

Abnormally high dopamine levels in subcortical areas, associated with positive symptoms like delusions and hallucinations.

Hypodopaminergia

Abnormally low dopamine levels in the pre-frontal cortex, associated with negative symptoms of schizophrenia.

Mesolimbic Pathway

The brain pathway where an excess of dopamine is linked to the development of positive symptoms.

Mesocortical Pathway

The brain pathway where a deficit of dopamine is linked to the development of negative symptoms.

$D2$ Receptors

Specific dopamine receptors that play a key role in guiding attention; schizophrenic brains may have more than twice the density of these receptors.

Phenothiazines

A class of anti-psychotic drugs, such as chlorpromazine, that reduce symptoms by temporarily blocking $D2$ receptors.

Clozapine

An anti-psychotic medication that reduces both dopamine and serotonin ($5-HT$) levels, often used for patients who do not improve with other treatments.

Amphetamines

Drugs that increase dopamine levels and can produce delusions and hallucinations, or worsen symptoms in schizophrenic patients.

PCP ('Angel Dust')

A drug that inhibits glutamate and produces psychotic symptoms, suggesting glutamate imbalance contributes to schizophrenia.

$$L-dopa$$

A medication used to raise dopamine activity in Parkinson's sufferers, which can cause schizophrenic symptoms if taken in excess.

Drug Aetiology Fallacy

The logical error of assuming that because a drug reduces symptoms of a disorder by changing neurotransmitter levels, the disorder must be caused by a lack or excess of that neurotransmitter.

Randrup and Munkvad ($1966$)

Researchers who found that injecting rats with amphetamines to increase dopamine activity led to behavioral indicators of schizophrenia, such as stereotypical movements.

Gjedde and Wong ($1987$)

Researchers who used PET scans to find that there are more than twice as many dopamine receptors in schizophrenics compared to controls.

Walter ($2009$)

A researcher who used MRI scans to find dopamine overactivity in the mesolimbic pathways of schizophrenics.

Diathesis-stress Model

The theory that schizophrenia develops from a combination of biological factors, such as neurochemical imbalance, and significant psychological stressors.

Reductionism

In this context, the criticism that the dopamine hypothesis explains a complex disorder through the action of a single neurotransmitter, ignoring social and psychological factors.