Class Notes (810,844)
Canada (494,281)
Psychology (6,045)
Lecture 9

Lecture 9 Neural damage and disorders.pdf

10 Pages
Unlock Document

Western University
Psychology 2220A/B
Beth Mac Dougall- Shackleton

Lecture 9 March-22-12 10:18 AM Psychology2220B Week 10 March 22, 2012 Neurodevelopmentaldisorders, brain damage, amnesias Outline • disorders of neurodevelopment(9.5) • causes of brain damage (10.1) • neuropsychologicaldiseases (10.2) • neuroplastic responses to brain damage (10.4, 10.5) • amnesic effects of MTL damage (11.1) Disorders of brain development • Autism • Williams Syndrome Disorders of Brain Development • Autism – complex disorder widely considered as a spectrum of disorders • core symptoms – reduced ability to interpret emotionsand intentions of others – reduced social communication – preoccupations with single activity/object • core symptomsdisplayed in most, but not all cases (in varying forms) • Aspergers is an example of high functioning autism spectrum disorder • a group of related disorders ranging in symptoms • e.g. Asperger’s syndromemay be considered a mild autistic disorder with preserved cognition and language abilities – Can have a normal or above normal IQ abilities • early signs (seen at a young age) – delayed language development – delayed social interaction • Not looking in the eye, etc • overall most prevalent childhood neurological disorder – increasing prevalency • increasing numbers or better detection and awareness? • Could be changes in environmentalsurrounding that lead to it • Or it could be that in the olden days, kids weren't diagnosed as autistic • So not sure which one it is Deficits indicate that the brain and cognition is really modular autism: a heterogeneous disorder • deficits are often quite specific • General IQ tests might be quite low – But at the same time, they can do things quite well, but don't have proper comprehension • Just one type of the deficit • e.g. mental impairment, but unimpaired art, music and memorization • reveals modular nature of cognition with specific deficits only in particular modules • reveals modular nature of cognition with specific deficits only in particular modules autistic savants • savant: intellectually impaired but displaying amazing highly specific abilities - highly specific cognitive ability – about 10% of autistic individuals have somesavantism • e.g. naming day of week of any date – see text for amazing examples • savant abilities seem to emergespontaneously • Have savant ability to do one kinds of thing • Autism and 'savantism' aren't overlapping - but about 50% of savants are autistic (not the same the other way around) autism and genetics • clearly underlying genetic contribution, but large environmentalinfluences also – Know that genes play a part, but that's not the only things • sibling with autism: 5% risk (versus approx ½% risk at large) • identical twin with autism: 60% risk – Even with all their genes in common,but there might be slight differences in early epigenetics – See this even when identical twins grow up in the exact same environment – So can see that many things effect autism, just not sure how and to what extent - interactionism • classic case of interactionism:inherited predisposition to develop autism in particular environments Neural Mechanisms of Autism • Understanding of brain structures involved in autism is still limited, so far implicated: – Cerebellum – Amygdala – Frontal cortex • Two lines of research on cortical involvementin autism: – Abnormal response to faces in autistic patients • Spend less time than non-autistic subjects looking at faces, especially eyes □ Others spend a lot more time looking at eyes • Low fMRI activity in fusiform face area – Possibly deficient in mirror neuron function Williams Syndrome - Fully intact and profound social skills • similar to autism in heterogeneity • however,very different impairments • highly sociable, empathic and talkative, sometimesgifted musically • Higher vocabulary and language usage • severe impedimentin spatial reasoning and mathematicalabilities, very low IQ • much rarer (1 in 7,500) • typically cardiac health issues • Evidence for a role of chromosome7 (as in autism) • General thinning of cortex at juncture of occipital and parietal lobes, and at the orbitofrontal cortex • “Elfin” appearance – short, small upturned noses, oval ears, broad mouths Brain Damage • brain damage can result from developmentaldisorder, or from a variety of causes in • brain damage can result from developmentaldisorder, or from a variety of causes in adulthood • Have a thinner cortex Autism is more common,but considered together, b/c they contrast so much in the symptomsand impairments (social vs. non) Causes of Brain Damage • Brain tumors • Cerebrovasculardisorders • Closed-head injuries (skull isn't broken - no direct cutting into the brain) • Infections of the brain • Neurotoxins • Genetic factors Brain Tumors • A tumor (neoplasm)is a mass of cells that grows independently of the rest of the body – a cancer • 20% of brain tumors are meningiomas – encased in meninges – Encapsulated, growing within their own membranes – Usually benign (b/c all of the cancers growth is within the case and nowhere else), surgically removable – Will have motorand cognitive deficits that are relative to where the tumor is growing • Reason for this is tumors grow and damage the brain through to pressure and infringince on other parts of the brain • Most brain tumors are infiltrating – Grow diffusely through surrounding tissue – Malignant, difficult to removeor destroy • About 10% of brain tumors are metastatic – they originate elsewhere, usually the lungs - and then move CerebrovascularDisorders • Stroke – a sudden-onset cerebrovascular event that causes brain damage – Cerebral hemorrhage – bleeding in the brain caused by a broken blood vessel – Cerebral ischemia – disruption of blood supply - b/c of blockage in a blood vessel and oxygen can't get to the brain • Third leading cause of death in the U.S. and most commoncause of adult disability – Disability is relative to area of brain affected • Cerebral Hemorrhage – blood vessel ruptures – Aneurysm – a weakened point in a blood vessel that makes a stroke more likely; may be congenital (present at birth) or due to poison or infection • Cerebral Ischemia – disruption of blood supply – Thrombosis – a plug forms in the brain – Embolism – a plug forms elsewhere and movesto the brain – Arteriosclerosis– wall of blood vessels thicken, usually due to fat deposits Damage Due to Cerebral Ischemia • Does not develop immediately - – It’s a slow and unfolding process – Will have responses of the neurons to the ischemia and eventual stroke – One neuron damage will effect the others through over release of glutamate - chain reaction • Most damage is a consequence of excess neurotransmitterrelease – especially glutamate • Blood-deprived neurons becomeoveractiveand release glutamate • Glutamate overactivatesits receptors, especially NMDA receptorsleading to an influx of Na + • Glutamate overactivatesits receptors, especially NMDA receptorsleading to an influx of Na + 2+ and Ca • lnflux of Na and Ca triggers – the release of still more glutamate – a sequence of internal reactions that ultimately kill the neuron • Ischemia-induced brain damage – takes time – does not occur equally in all parts of the brain – mechanismsof damage vary with the brain structure affected Closed-Head Injuries • Brain injuries due to blows that do not penetrate the skull – the brain collides with the skull – Contrecoup injuries – contusions are often on the side of the brain opposite to the blow • Contusions – closed-head injuries that involve damage to the cerebral circulatory system; hematoma(bruise) forms • Concussions – when there is disturbance of consciousness following a blow to the head and no evidence of structural damage – But can cause long term neurological effects Types of damage Hit on one side of the head and end up having an injury on the opposite side (on the inside) - contrecoup Can have damage through the brain moving around back and forth - tortion Have swelling and bleeding • While there is no apparent brain damage with a single concussion, multiple concussions may result in a dementia referred to as “punch-drunk syndrome” -causes dementia/intellectual deterioration • cumulative concussions –depression or anxiety – higher risk for future concussions Infections of the Brain • Encephalitis – the resulting inflammationof the brain by an invasion of microorganisms – Bacterial infections • Often lead to abscesses, pockets of pus • May inflame meninges, creating meningitis - which then effects activity of the underlying nervous tissue • Treat with penicillin and other antibiotics – Viral infections • Some preferentially attack neural tissues • Some can lie dormant for years • syphillis syphilis • sexually transmittedvia genital sores • after dormancy bacteria (spirchetes) attack several tissues including the brain resulting in dementia – general paresis Many diseases have the ability to cause brain damage if the infection gets into the brain Most commonhere is meningitis Neurotoxins • May enter general circulation from the GI (gastrointestinal) tract or lungs, or through the skin • Toxic psychosis – chronic insanity produced by a neurotoxin • 'mad hatter' = hat makers were exposed to high levels of mercury that eventually caused brain • 'mad hatter' = hat makers were exposed to high levels of mercury that eventually caused brain damage Genetic Factors • Most neuropsychologicaldiseases of genetic origin are associated with recessivegenes – think about Evolution here… – Natural selectionwill select for the healthier gene • Down syndrome – 0.15% of births, probability increases with advancing maternal age – Extra chromosome21 created during ovulation – Characteristic facial development,impaired mental developmentand other health problems Programmed Cell Death • All causes of brain damage discussed above produce damage, in part, by activating apoptosis NeuropsychologicalDiseases • Epilepsy • Parkinson’s disease • Huntington’s disease • Multiple sclerosis • Alzheimer’s disease Epilepsy • Primary symptomis seizures, but not all who have seizures have epilepsy • Epileptics have seizures generated by their own brain dysfunction • Affects about 1% of the population • Difficult to diagnose due to the diversity and complexity of epileptic seizures • Types of seizures – Convulsions – motor seizures = loss of rigidity, tremorsand motor balance impairment – Some are merely subtle changes of thought, mood, or behavior • Causes – Brain damage – Genes – over 70 known so far – Faults at inhibitory synapses - prevents muscles from relaxing • Diagnosis – EEG – electroencephalogram – Seizures associated with high amplitude spikes – Where the seizure starts is called the locus • Seizures often preceded by an aura, such as a smell, hallucination, or feeling – Aura’s nature suggests the epileptic focus - what causes the seizure – Warns epileptic of an impending seizure • involves whole brain: generalized epilepsy - spreads across the brain • involves part of the brain: partial epilepsy - limited to specific regions of the brain Partial Seizures Simple vs complexrefers to symptomsand not cognitive activity • Simple – Symptomsare primarily sensory or motoror both (Jacksonian seizures) – Symptomsspread as epileptic discharge spreads • Complex – often restricted to the temporallobes (temporallobe epilepsy) – Patient engages in compulsive and repetitivesimple behaviors (automatisms)(aren't aware of it) – More complex behaviors that seem normal Generalized Seizures - involvesthe whole brain Generalized Seizures - involvesthe whole brain • Grand mal – Loss of consciousness
More Less

Related notes for Psychology 2220A/B

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.