PSYB65H3 Chapter Notes - Chapter 16: Limb Music, Soltyrei, Phenytoin

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Chapter 16 notes: What happens When the Brain Misbehaves?
Research Focus 16-1: Posttraumatic Stress Disorder
patients have reductions in the hippocampus and amygdala of the temporal lobes
and the frontal cortex
this is associated with reduced cortical thickness
The search for neural markers:
Freud believed that mental illness results from the failure of the repressive
processes: the result from the emergence of unconscious drives into voluntary,
conscious behaviour
The components of the mind:
oId: “Instinctual drives” of sex and aggression; part of mind that is
unconscious
oEgo: the rational part of mind that has conscious experience
oSuperego: part of mind that tries to suppress the id
Psychoanalysis aims to trace symptoms back to their unconscious roots and thus
expose them to rational judgement
Limbic system and brainstem have properties akin to the id (emotional and
motivated behaviours)
Neocortex has properties akin to the ego (allows us to learn and solve everyday
problems)
Frontal cortex has properties akin to the superego (enables to us to be aware of
others and learn to follow social norms)
Neuropsychoanalysis: “movement within neuroscience and psychoanalysis to
combine the insights of both to yield a unified understanding of mind and brain”
16.1: Multidisciplinary Research on Brain and Behavioural Disorders
Cause of Abnormal Behaviour:
For neurological disorders:
oGenetic errors (like in huntington’s disease)
oEpigenetic mechanisms at work prenatally, later in life, and in succeeding
generations
oProgressive cell death b/c of neurodegenerative causes (Parkinson’s or
Alzheimers)
oRapid cell death (strokes or traumatic brain injury)
oLoss of neural function and connections (multiple sclerosis and
myasthenia gravis)
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Less known about behavioural-psychiatric disorders
oTable 16-1 on specific behavioural disorders (pdf page 597, textbook page
569)
oMicroscopic level= genetic error (eg. Those responsible for Tay-Sachs
disease and Huntington’s disease); probably linked to hormonal or
developmental anomalies
oGenetic vulnerability to stress, infection, or pollution may be the immediate
cause of some abnormal conditions: but not all cases:
oAbnormal behaviour can arise strictly from epigenetic factors that
influence gene expression and function:
Some possible environmental triggers: poor nutrition; exposure to
toxins, manufactured chemicals, naturally occurring toxins, and
infectious agents; negative experiences (developmental
deprivation, extreme psychosocial neglect, traumas); chronic stress
later in later life
Investigating the Neurobiology of Behavioural Disorders:
Phenylketonuria (PKU): “Behavioural disorder caused by elevated levels of the
amino acid phenylalanine in the blood and resulting from a defect in the gene for
the enzyme phenylalanine hydroxylase; the major symptom is severe mental
retardation”
oEasily treated by restricting the dietary intake of phenylalanine (foods with
high protein eg. Beef, fish, cheese, and soy)
oExpecting mothers with PKU provide high phenylalanine levels in utero
environment but can also be controlled by dietary restrictions
oTable 16-2 PKU: Known Neurobiological Pathogenesis of a Behavioural
Disorder (pdf page 598, textbook page 570)
For most psychiatric disease the underlying pathology is unknown (unlike PKU)
Diagnosis Challenges:
oMost diagnostic info is collected by individual and their family but can often
be notices selectively (eg. You believe someone has a memory problem,
so you notice every memory mistake they make that could really be
normal)
oInfo often not specific enough when identifying symptoms (eg. Forgetting
words, places, habits all have different underlying pathologies in brain
system: saying “memory problems” isn’t enough)
oDiagnosis evaluators with different conceptual biases shape and filter the
questions they ask and info they gather (biases!)
Research Challenges:
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oThe nervous system is more complicated than other body systems: brain
has more variety of cell types than any other organ
oBrain has multiple receptor systems: “no clear demonstration of a single
receptor system with a specific relation to a specific behaviour has been
made”
oNeural plasticity makes it hard to tie certain things to behaviour
o“compensatory plasticity”- people can change their behaviour to adapt to
neural change, and they can display abnormal behaviour without obvious
brain pathology
oResolution of technology may lack detail to detect subtle neuronal change
(eg, drop in dendritic-spine density)
oWhen using animals (like rats) as a model for humans, it is often
oversimplifying the neurobiology behind abnormal behaviour
Also causes limitations when looking at possible cures or
medication
Review 16-1: (I copied the answers from the back of the book, including the short
answer for number 5)
1. Neural correlates of Freud’s id, eg, and super ego could be, respectively, the
brainstem and limbic system, ventral frontal and posterior cortex, and dorsal
frontal cortex.
2. Causes pf abnormal behaviour include, genetic errors, epigenetic mechanisms,
progressive cell death, rapid cell death, and loss of neural connections.
3. For most psychiatric disorders, the causes are unknown, but PKU
(phenylketonuria) is an exception.
4. A major challenge in diagnosing disorders is that diagnosis tends to be
subjective.
5. Describe a research challenge for understanding brain injury:
Brain pathology can exist without obvious clinical symptoms and clinical
symptoms without obvious pathology.
16.2: Classifying and Treating Brain and Behavioural Disorders
About ¼ people in U.S. suffer with a mental disorder, but only some of them
receive treatment
Identifying and Classifying Behavioural Disorders:
Epidemiology=the study of the distribution and causes of diseases in human
populations
Diagnostic and Statistical Manual of Mental Disorders (DSM)= the American
Psychiatric Association’s classification system for psychiatric disorders:
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Document Summary

Research focus 16-1: posttraumatic stress disorder: patients have reductions in the hippocampus and amygdala of the temporal lobes and the frontal cortex this is associated with reduced cortical thickness. 16. 1: multidisciplinary research on brain and behavioural disorders. Cause of abnormal behaviour: for neurological disorders, genetic errors (like in huntington"s disease, epigenetic mechanisms at work prenatally, later in life, and in succeeding generations, progressive cell death b/c of neurodegenerative causes (parkinson"s or. Alzheimers: rapid cell death (strokes or traumatic brain injury, loss of neural function and connections (multiple sclerosis and myasthenia gravis, less known about behavioural-psychiatric disorders, table 16-1 on specific behavioural disorders (pdf page 597, textbook page. Some possible environmental triggers: poor nutrition; exposure to toxins, manufactured chemicals, naturally occurring toxins, and infectious agents; negative experiences (developmental deprivation, extreme psychosocial neglect, traumas); chronic stress later in later life. Also causes limitations when looking at possible cures or medication.

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