Declarative Memory Knowing that Explicit knowledge Tulving: Two subdivisions i)Semantic ii)Episodic
Episodic Memory Memories that depend on temporal, spatial or contextual cues in order the retrieve the information (= explicit memory) Consists of additional knowledge of personal experience Involves remembering specific events and episodes in the context in which they occur ***Typically disrupted in amnestic conditions
Measures of Episodic Memory Numerous Examples: WMS-IV/WMS-III: Paired Associates, Logical Memory, Visual Reproduction, Designs Rey Complex Figure RAVLT/CVLT/SRT
Selective Reminding Test
A taxonomy of memory disorders AMNESIA Neurological Permanent Progressive Stable Material Specific Global Frontal Amnesia Amnesic Syndrome Transient Global Amnesia Post-Traumatic Amnesia Post ECT or Convulsion Psychogenic Selective Amnesia Psychotic Conditions
Material Specific Memory Disorder Reflection of lesion laterality – Pathology of the dominant Vs nondominant hemipshere 1. Temporal Lobe Epilepsy (TLE) Milner (1958, 1962): Patients undergoing unilateral temporal lobe resection for relief of intractable complex partial seizures Temporal lobectomy: Anterior portion (5cm) of temporal lobe removed including the anterior portion of the hippocampus Memory Disorder: Material specific not modality specific
Left TL resection: Verbal Memory Deficit (logical memory, word lists) Right TL resection: Nonverbal Memory Deficit (maze learning, design recall, recall of faces) Hippocampus thought to be the important structure
TLE – Case Example Case: KE Age:19 years Sex: Female History:6 month history of complex partial seizures Eduction: HSC graduate, Commenced first year of a degree in PE teaching – deferred due to memory problems
IndexIndex Score Verbal Comprehension101 Perceptual Reasoning108 Working Memory109 Processing Speed95 Full Scale101 General Ability1`05
KA: Wechsler Memory Scale-IV (WMS-IV) Index Score Auditory Memory 87 Visual Memory105 Visual Working Memory 109 Immediate Memory 95 Delayed Memory 71
KA: Further Memory Testing Selective Reminding Test CLTR = 50 (Mean = 115, SD = 15.5) Recognition Memory Test Scale Score Words 5 Faces11 15-Item Visual Memory Test Raw score = 15/15
15-Item Visual Memory Test ABC IIIIII abc 123
KA: Assessment of adaptive abilities Controlled Oral Word Association Test (COWAT) Words = 39 (Mean = 41.5, SD = 6.7) Wisconsin Card Sorting Test Categories = 6 Perseverative Responses = 11 Rey Complex Figure Test Copy = 34, Recall = 22 Booklet Category Test Errors = 23
KA: Rey Figure Copy
KA: Rey Figure Recall
Material Specific Disorders of Memory (cont) 2. Cerebrovascular Disorders Disruption of brain function secondary to vascular pathology (includes haemorrhage (rupture), narrowing (stenosis) and occlusion due to presence of an obstructing clot (thrombus or embolus) Branches of the posterior cerebral artery supply the inferior and medial surfaces of the temporal lobes and posterior sections of the hippocampus. Thus, infarction (tissue death) may result from occlusion and produce a material specific memory disorder Unilateral thalamic infarction (secondary to PCA disturbance) may also produce a material specific disorder of memory.
Specific Disorders of Memory Topographical disorientation Damage to the right tempero- parietal areas (MCA) Unable to find way around. Tactile Memory Impairment reported in patients with unilateral temporal lobe lesion resulting from CVA with loss demonstrated in hand contralateral to the lesion.
BS: Lateralised (R.Hem) Dysfunction 45 yo female 9 years education DSS (clerical) for 17 years 3-4 months preceding ABI worked as a taxi driver 1/1/02 assaulted during the course of her work PTA: several days duration (no recollection of visitors while in hospital, son receiving HSC results)
CT (2006): Local area of enlargement of the temporal horn of the right lateral ventricle, enlargement of the right Sylvian fissure. Appearances consistent with an area of local atrophy. Psych Tx for PTSD Psychiatrist noted that she intermittently complained of memory problems and geographical disorientation
Case BD Assessment February 2007 Attended unaccompanied Fully cooperative c/o - memory problems (eg. Forgets where she is meant to be driving to, gets lost even when driving to familiar places, misplaces her personal belongings) - irritability
WAIS-IV Verbal IQ = 116 PIQ = 110 Working Memory = 117 Processing Speed = 104 Full Scale IQ = 111 General Ability = 113
WMS-IV INDEXACTUALPREDICTED Auditory Mem Visual Mem75106 Visual Working Mem Immediate Mem_107 Delayed Mem_106
Base Rates (General Ability) AM - >25% VM - <1%
BD: Additional Memory Tests Selective Reminding Test Consistent Long-Term Retrieval – Average Rey Complex Figure Test Copy = 25 Recall = 4.5 (<1 st percentile)
BD: Adaptive Abilities and Emotional Status Trail Making Test Part A = 26 seconds, 0 errors Part B = 50 seconds, 0 errors Controlled Oral Words Association Test (COWAT) Words = 45, Errors = 3 Wisconsin Card Sorting Test Categories = 6, Errors = 12 Perseverative Responses = 6 (Above Average) Booklet Category Test Errors = 107 (Impaired) Depression, Anxiety, Stress Scales Depression = 40 (Ex.S.), Anxiety = 36 (Ex.S.), Stress = 32 (Ex.S.)
BD: Opinion The results of the assessment revealed clear evidence of cognitive impairment. Although generally able to achieve at an average to high average level on measures of verbal ability, her nonverbal skills proved markedly disordered. Specifically, she demonstrated difficulty in acquiring, retaining and processing visuospatial material. Although she is clearly suffering significant levels of emotional distress, reference to these factors alone would not appear to be sufficient to account for all of the deficits seen on testing.
Neither depression nor anxiety would be expected to produce a material-specific disorder of memory and adaptive ability. A disparity between performance on measures of verbal and nonverbal ability, when of the magnitude that was evident in the present case, is strongly suggestive of lateralised cerebral pathology. The profile of performances returned on testing would suggest that there has been damage to the frontal and temporal lobes of the nondominant (right) hemisphere. The CT report provides independent evidence of focal damage to these areas.
BD: Opinion (cont) Given the results of the assessment it is not surprising to learn that BD complains of a tendency to get lost while driving and occasion geographic disorientation. The ability to remember routes and to understand spatial relations is known to be mediated by the right hemisphere. Recalling the temporal detail of various events is thought to represent one of the functions that is subserved by the frontal lobes. As stated above, the results would suggest that these areas have been damaged.
BD: Opinion (cont) On a day to day level BDs deficits are most likely to manifest as a difficulty in recalling visual information (scenes, routes, faces etc), a difficulty in planning her approach to nonverbal tasks (eg. when assembling an item or dealing with procedures that involve a number of steps) and an inability to reason and problem-solve in the nonverbal modality. She may experience difficulty in learning the requirements of any new position, particularly if the work involves nonverbal displays or tasks. She should be encouraged to verbalise information and to make written note of new procedures. Her ability to operate a computer may be
compromised in that she is likely to find it difficult to remember the meaning of various symbols and the full range of responses that a particular visual cue is designed to elicit. Even when her mistakes are drawn to her attention she is likely to have difficulty in generating some alternative method of response. Modelling of the correct procedure would be of use. Flow-charts or other nonverbal displays are unlikely to be of assistance.
Frontal Amnesia A. Organisational Deficits Simple registration and recall not affected by frontal lesions Memory problems may be secondary to an inability to organise material for the purpose of committing it to memory i.e. failure to impose a meaningful structure on the information, to generate appropriate learning strategies Frequent concomitant of traumatic brain injury Manifest on tests such as Rey Complex Figure, Rey Auditory Verbal Learning
Frontal Amnesia B. Retrieval Problems Retrieval involves strategic problem-solving. Often disturbed following frontal lesions Patient with a retrieval deficit will demonstrate a disturbance of free recall Recognition memory should, however, be intact eg. RAVLT: poor score on recall of list A (trials 1- 6) recognition 15/15 One advantage of WMS-III relative to WMS-R
Frontal Amnesia C. Temporal Discrimination Increasing attention being devoted to this aspect of memory Patients with frontal lesions are markedly impaired in making temporal discriminations. Great difficulty in judging recency and temporal order and in reconstructing sequences. Note, deficits of temporal ordering may be seen in the absence of fontal lobe pathology Two processes involved: a) Encoding of information needed for temporal memory b) Effective processing of retrieved information regarding temporal order In patients with lesions of the frontal lobes deficit lies in b) ie. Is one of faulty processing (c.f. WKS patients where the deficit lies in a)).
General Amnesic Syndrome Definition A permanent, stable and global disorder of memory due to organic brain dysfunction which occurs in the absence of any other extensive perceptual or cognitive disturbance. NB. Permanency Stability Pervasiveness Specificity
Clinical Features of the Amnesic Syndrome 1. Profound difficulty or total inability to acquire new material (anterograde amnesia) 2. Preservation of immediate memory as measured by tasks such as digit span 3. Preservation of semantic memory 4. Preservation of procedural learning 5. Some retrograde amnesia (variable across patients)
Neuopathology Brain structures implicated: 1. Bilateral damage to the mesial temporal lobes of both the right and left hemispheres Within these areas the hippocampus has been seen to represent the crucial structure 2. Structures within the diencephalon and specifically: Nuclei within the thalamus Mamillary bodies Mamillo-thalamic tract Fornix All above structures represent part of the limbic system
Aetiology GAS typically seen in association with 1. Wernicke-Korsakoff Syndrome 2. Herpes Simplex Encephalitis 3. Hypoxia 4. Anterior Communicating Artery Aneurysm 5. Thalamic Infarction 6. Temporal Lobe Resection Other causes: CVA Tumour
Wernicke-Korsakoff Syndrome Typically the result of chronic alcoholism Principle cause: Thiamine deficiency Results in damage to the subcortical structures and in particular the diencephalon Minimal requirement: Lesion of the mamillary bodies and dorsomedial nucleus of the thalamus Typically additional lesions in the frontal lobes (atrophy) due to alcohol neurotoxicity and often the medial temporal structures including the hippocampus Treatment. Thiamine. Amnesia often persists
WKS: Characteristics 1. Normal memory span 2. Severe anterograde amnesia 3. Normal rate of forgetting 4. Extensive, temporally graded retrograde amnesia 5. Confabulation present 6. Cued recall better than spontaneous recall 7. Recognition relatively intact 8. Poor at recency judgements 9. Frontal lobe dysfunction typically present