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Disorders of memory made simple John O’Donovan Functional anatomy of cognitive functions Distributed • Consciousness • Memory • Higher order intellectual functions, personality and executive functioning Focal • Dominant versus non dominant hemisphere Attention • • • • ARAS Thalamus Hypothalamus Multimodal association cortex • Right parietal cortex Tests of attention • Orientation • Digit span • Recitation of months of year or days of weeks • Words forwards and backwards • Serial 7s • Remember, if attention does not work then neither does anything else. Memory • Very messy-need to know it inside out. • You will have questions on memory as it covers psychology, neurology and psychiatry. Episodic Episodic Semantic Memory divisions Explicit or declarative • Available to conciousness Implicit or procedural • Not available to consciousness Explicit memory Epidodic • Personal events • Autobiographical events Semantic • General knowledge • • • • • Capital of France? • Who wrote War and Peace? • Distance from Exeter to Plymouth? Birthday last year? First kiss? First job? What was on TV last night? Memory divisions Episodic • Hippocampal formation • Limbic system • Diencephalic system: basal forebrain and thalamus. Semantic • Temporal neocortex with perhaps more verbal semantic memory on left and more visual semantic memory on right. Implicit • • • • Motor skills Basal ganglia Cerebellum Riding a bike, car, playing the piano, motor skills. Short versus long term memory • Avoid the term short term memory, it’s a mess. • Think instead in terms of working memory and long term memory. • Simple concept of working memory, remembering information for 5-30 minutes • Working memory is better as a concept. Working memory and loops • Central executive probably based in frontal lobes • Phonological loop to verbal area in dominant hemisphere and visuospatial loop to non dominant loop • Ongoing simultaneously and not completely independent of long term memory Retrograde and anterograde memory • Retrograde: recall of previously learnt material. • Anterograde: acquisition of new memories. Where is memory stored? • Seems that verbal memory is dominant hemisphere • Seems that visual memory also known as iconic memory is non dominant. The amnesic syndrome • Pure deficit in memory. • All other areas more or less intact. Amnesic syndrome Acute and transient • TGA • Epilepsy • Closed head injury • Drugs • Psychogenic Chronic • • • • • • • Hippocampal Herpes simplex Anoxia Surgical resection of temporal lobes Bilateral posterior cerebral artery occlusion Closed head injury Alzheimer’s disease • • • • Diencephalic Korsakoff’s 3rd ventricle tumours SAH-ACAM anuerysm Amnesic syndrome • 1 generally preserved IQ. • 2 preserved short term/working memory for example digit span. • 3 anterograde amnesia • 4 retrograde amnesia which is generally more severe in diencephalic amnesia • 5 preserved procedural/implicit memory Amnesic syndrome Diencephalic • Problems with encoding • Problems with retrieval of memory from long term storage Hippocampal • The main problem is either encoding or consolidation, unlikely to be retrieval. Memory MCQs Semantic memory • Is constantly acquired • Is intact in Korsakoff’s • Is intact in Alzheimer’s Disease • Is intact in semantic dementia • Non dominant temporal lobe lesions can result in prosopagnosia for famous faces Episodic memory • Is impaired in Alzheimer’s. • Is the same as autobiographical memory. • Is normal in poorly controlled epilepsy • Is intact in Korsakofff’s • Is normal in psychogenic fugue. Memory MCQs Implicit memory • If brought into consciousness, is then explicit. • Is affected by cerebellar disease. • Also has an autobiographical element. • Is intact in the amnesic syndrome • Cannot be tested Short term memory • Has a time limit of 30 minutes • Is the same as working memory • Is intact in Korsakoff’s • Is a term best avoided due to imprecision. • Is intact in Alzheimer’s disease.