Disorders of memory made simple John O’Donovan

Functional anatomy of cognitive functions Distributed Focal Consciousness Memory Higher order intellectual functions, personality and executive functioning 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 Implicit or procedural Available to conciousness Not available to consciousness

Explicit memory Epidodic Semantic Personal events Autobiographical events Birthday last year? First kiss? First job? What was on TV last night? General knowledge Capital of France? Who wrote War and Peace? Distance from Exeter to Plymouth?

Memory divisions Episodic Semantic Hippocampal formation Limbic system Diencephalic system: basal forebrain and thalamus. 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 Chronic TGA Epilepsy Closed head injury Drugs Psychogenic 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 Hippocampal Problems with encoding Problems with retrieval of memory from long term storage The main problem is either encoding or consolidation, unlikely to be retrieval.

Memory MCQs Semantic memory Episodic 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 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 Short term 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 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.