Dopamine Hypothesis Explanations Flashcards
What was the orignal hypothesis?
-suffered from an excessive amount of dopamine
-causes neurones to fire too often
-message overload = schizophrenic symptoms
What does the updated version state?
-not an excess of DA but there are too many receptors
-high amount of D2 receptors = more dopamine binding
-supported by Comer
What did Comer state?
-disturbances with dopamine may lead to problems with attention and perception
-both linked to schizophrenia
What do anti-psychotic drugs do?
-block activity of dopamine in the brain
-by reducing stimulation of dopamine system
What does anti-psychotic drugs use to support this explanation?
-the fact that they block the action of dopamine, which results in symptoms being alleviated
-suggests that dopamine is involved in schizophrenia
Outline the dopamine hypothesis
-original suffered from an excessive amount of dopamine
-which causes neurones to fire too often
-updated version = not an excess of DA but there are too many receptors
-high D2 receptors results in more dopamine binding
What did David and Khan study?
-PET scans
-excess dopamine activity has been discovered via PET scans in the brains of S especially those with + symptoms
-high dopamine activity in sub cortex associated with poverty of speech
What does hypodopaminergia show?
-more recent versions of hypothesis have focused on low levels of dopamine in the prefrontal cortex
-responsible for thinking and decision making
What did Patel find about neural imaging?
-PET scans reveal lower dopamine levels in dorsolateral prefrontal cortex
What did Wang and Deutch find out about animal studies?
-depletion of dopamine in prefrontal cortex of rats
-resulted in cognitive impairment which they reversed with an antipsychotic drug
What did Weinberger find out about neural correlates?
-prefrontal cortex is the area involved in executive control
-like focus and attention
-this is impaired in S patients
Grey matter - neural correlates
-individuals with S have reduced volume of grey matter
-people displaying negative symptoms have enlarged ventricles
-a consequence of the loss of grey matter in nearby parts of the brain
White matter - neural correlates
-Du found reduced myelination of white matter pathways in schizophrenic patients
-particularly the case in neural pathways between the PFC and hippocampus
What is support for the dopamine hypothesis?
-Patel used PET scans to reveal lower dopamine in dorsolateral prefrontal cortex
-not as simple as low dopamine leading to S, but low or high dopamine in certain areas of the brain
What is a contradiction for the dopamine hypothesis?
-extrapolation
-some studies support the revised hypothesis such as Wang and Deutch use animals in their studies
-hard to apply studies from animals to humans as they are physiologically different
