Cognition and Reward Flashcards
What are positive symptoms?
distorted or excess of normal functioning
What are positive symptoms of Schizophrenia?
delusions, hallucinations and thought disorders
What are negative symptoms?
deficit or decrease in normal functioning
What are negative symptoms of Schizophrenia?
flattened emotional response, poverty of speech, social withdrawal and anhedonia
What is the early neurodevelopment model of Schizophrenia?
during the second trimester lesions appear which lie dormant until the brain matures and required these areas (Murray and Lewis 1987)
What is the late neurodevelopment model of Schizophrenia?
an abnormality in peri-adolescent synaptic pruning (Feinberg 1983)
What is the 2 hit model of Schizophrenia?
the combination of both early and late developmental problems
What physical brain change is observed in Schizophrenia?
ventricular enlargement, loss of grey matter reduced temporal, frontal and subcortical matter
What is hypofrontality?
a decrease in blood flow to the prefrontal cortex (mesocortical area) leading to decreased brain activity during high cognitive load
What neurocognitive deficits are observed in Schizophrenia?
lower IQ, attentional deficit, working memory deficit, planning and information processing deficit, lack of filtering out irrelevant information
What neurophysiological deficits are observed in Schizophrenia?
pre-pulse inhibition and oculomotor functions
What is pre-pulse inhibition?
schizophrenics are unable to inhibit a startle response despite being given a preceding stimulus
What are oculomotor functions?
tracking a spot smoothly and suppression of looking at a target
What does the mesolimbic system consist of?
ventral tegmentum and nucleus accumbens
How is the mesolimbic system related to Schizophrenia?
an overactive mesolimbic system (increased dopamine) leads to positive symptoms
How is the mesocortical system related to Schizophrenia?
reduced activity in the mesocortical (reduced dopamine) leads to negative symptoms
What does the mesocortical system consist of?
ventral tegmentum and prefrontal cortex
What is some evidence for the role of dopamine in Schizophrenia?
effectiveness of dopamine antagonists, drugs boosting dopamine can induce positive symptoms, increased dopamine in caudate putamen
What are some problems with the dopamine hypothesis?
only explains positive symptoms, dopamine antagonists exacerbate negative symptoms
What is the glutamate hypofunctioning theory?
positive symptoms in Schizophrenia such as delusions and hallucinations are the result of decreased glutamate
What evidence is there for glutamate hypofunctioning theory?
NMDA receptor antagonists (ketamine) can induce hypo function and glutamate agonists improve both positive and negative symptoms
How does glutamate affect dopamine?
glutamate excites GABA which then causes the inhibition of dopamine
How can glutamate affect neurodevelopment?
excitotoxicity can cause problems with neural pathways, migration, plasticity and pruning
What can glutamate excitotoxicity lead to in later life?
glutamate hypofunctioning