Neurobiology of Abnormal Mood Flashcards
What skills do we need to be able to survive?
To identify stimuli predicting appetitive or aversive consequences and to generate then integrate behaviour or other psychological consequences to these stimuli
What is the function of the appetitive system?
To mediate seeking and approach behaviours
What does the appetitive system involve?
Ascending dopamine systems
What are the components of the ascending dopamine systems involved in the appetitive system?
Mesolimbic/cortical projections (ventral striatum)
Dorsal striatum = movement
Amygdala = conditioning and learning
Anterior cingulate = attention, conflict, response selection
Orbitofrontal cortex = relative reward preference, rule learning
What is the function of the aversive system?
Promote survival in event of threat
What is involved in the aversive system?
Ascending serotonin systems NA/CRF/peptide neurotransmitters Central nucleus of amygdala Hippocampus Ventroanterior and medial hypothalamus Periaqueductal grey matter
What is depression?
Altered sensitivity/accuracy of brain systems evaluating rewards and cues predicting reward within the environment
What is anxiety?
Altered sensitivity/accuracy of brain systems evaluating threat and cues predicting threat within the environment
What are some reasons why mood disorders are recurrent?
Abnormal brain development, endocrine/metabolic causes, genetic and developmental effects, adverse life effects, lack of psychological resilience, cultural aspects
Deficiency of which neurotransmitters are linked with depression?
Serotonin, norepinephrine, dopamine, GABA, BDNF, somatostatin
Excess of which neurotransmitters are linked with depression?
Acetylcholine, substance P, CRH
How does serotonin influence depression?
Decrease in receptor binding through cortical and subcortical regions
Reduction in reuptake sites
Blunting of serotonin-mediated endocrine responses
How does norepinephrine influence depression?
Decrease neurotransmission leading to anergia, anhedonia and decreased libido
How does dopamine influence depression?
Hypoactive D1 receptor
Increase binding of D2/D3 receptors in striatal regions
Low levels of HVA in CSF
What effect do antidepressants have on GABA?
Receptors are upregulated
What happens to the HPA axis in depression?
Its upregulated with a down regulation of its negative feedback controls
What happens to CRF in depression?
It’s hypersecreted from the hypothalamus and induces release of ACTH from the pituitary
What is the action of ACTH in depression?
Interacts with receptors on adrenocortical cells and cortisol is released from adrenal glands = may cause adrenal hypertrophy
What happens to negative feedback of cortisol in depression?
It is impaired = leads to continual activation of HPA axis and excess cortisol release
What effect does excess cortisol have in depression?
Receptors become desensitised leading to increased activity of pro-inflammatory immune mediators and disturbances in neurotransmitter transmission
What is serotonin function like in depression?
Abnormal before, during and after episodes = may explain why 80% of patients have recurrences of major depressive episodes
What receptor plays a major role in how serotonin communicates with the rest of the brain?
5-HT1A = involved in pathology of mood disorders and action of antidepressants
What happens to the norepinephrine system in depression?
Seems hyperactive but since there are fewer noradrenergic neurons, this can lead to deficiency
How can adverse childhood experiences influence the norepinephrine system?
Produce overactive responsiveness that persists into adulthood = adult will deplete NE in stressful situations
