NEUR30003 Lecture Notes - Lecture 28: Encephalization, Advantageous, Microarchitecture
18 Jun 2018
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Lecture 28
1. Despite the efficacy of some drugs in treating symptoms of mental disease, their
biological basis is poorly understood (but clealry complex). Not knowing how the mind is
created by the activity of the brain, and not knowing the etiology and neurobiological basis of
mental disease has not prevent the development of effective treatments.
2. Although non-drug treatments are still used and have varying efficacy, the dominant
treatment paradigm is pharmacological. The drugs that have proved to be effective in
management of schizophrenia and depression have a rational basis in the modulation of
neurotransmitter levels at central synapses (particularly those of diffuse modulatory
systems), but their slow onset of effect is hard to explain.
3. The distribution of the molecular targets of these drugs seem to be much broader that the
regions of abnormal activity in these disorders: The drugs that have proved to be effective in
management of schizophrenia and depression have a rational basis in the modulation of
neurotransmitter levels at central synapses (particularly those of diffuse modulatory
systems), but many aspects of drug action and drug treatments suggest a much more
complicated picture.
4. More consistent with the known pharmacology are the effects of abused or recreational
drugs on the nervous system. Drugs with serotonergic actions appear to modulate cortical
function to produce psychedelic experiences. Opiates act on a different part of the reward
pathway, probably on the dopaminergic neurons in the ventral tegmental area of the
brainstem, and produce hedonic experiences and vegetative behaviour.
5. Alcohol (ethanol) has a number of actions on the brain - at a behavioural level it produces
relaxation and disinhibition, it is a powerful depresant and can casue confusion, memory
loss, and unconsciousness and death. It seems to act on GABA receptors as an agonist, but
is also know to effect glutamte, serotonin, dopamine and opioid neurotransmission. Long-
term abuse kills neurons in cortex (esp. pfc), hypothalamus and cerebellum.
6. Little agents (like drugs) can have large, and largely coherent effects, but the suggestion
that some global brain property (or mental state) is associated with the action of a single
neurotransmitter is wrong. The connection between these components / agents / lesions and
their effects on mental state is complex because they are mediated by the most complex
structure in the known universe: the brain.
- Disorders of thought and mood
- Mental disorders have complex aetiologies that involve interactions among multiple
genetic and non-genetic risk factors.
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- Major Depressive Episode:
- In major depressive disorder affective or mood symptoms include depressed mood
and feelings of worthlessness or guilt, cognitive and somatic symptoms but also
behavioral symptoms including social withdrawal and agitation.
- Manic Depression:
- Manic episodes greatly elevated mood, creativity, profusion of thought and pressured
speech. May manifest as grandiosity and confidence or anxiety and aggression.
Feeling of increased or limitless energy, including reduced need for sleep. Typically
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highly distractible, irritable, and exhibiting poor judgment. Extreme mania may
include disordered (psychotic) thought.
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- Depression - increased activity in medial ventral region, mediodorsal thalamus
- Abnormally high blood flow abates with resolution of depression, regardless of the
treatment (or lack of) associated with remission
- Treatment of Depression: Electroconvulsive therapy; psychotherapy; antidepressant
drugs (Tricyclics; SSRIs NERIs; Monoamine oxidase inhibitors)
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Document Summary
Lecture 28: despite the efficacy of some drugs in treating symptoms of mental disease, their biological basis is poorly understood (but clealry complex). Drugs with serotonergic actions appear to modulate cortical function to produce psychedelic experiences. It seems to act on gaba receptors as an agonist, but is also know to effect glutamte, serotonin, dopamine and opioid neurotransmission. The connection between these components / agents / lesions and their effects on mental state is complex because they are mediated by the most complex structure in the known universe: the brain. Mental disorders have complex aetiologies that involve interactions among multiple genetic and non-genetic risk factors. In major depressive disorder affective or mood symptoms include depressed mood and feelings of worthlessness or guilt, cognitive and somatic symptoms but also behavioral symptoms including social withdrawal and agitation. Manic episodes greatly elevated mood, creativity, profusion of thought and pressured speech. May manifest as grandiosity and confidence or anxiety and aggression.
