2Declarative Memory Knowing that Explicit knowledge Tulving: Two subdivisionsi) Semanticii) Episodic
3Episodic Memory ***Typically disrupted in amnestic conditions Memories that depend on temporal, spatial or contextual cues in order the retrieve the information (= explicit memory)Consists of additional knowledge of personal experienceInvolves remembering specific events and episodes in the context in which they occur***Typically disrupted in amnestic conditions
10Material Specific Memory Disorder Reflection of lesion laterality – Pathology of the dominant V’s nondominant hemipshereTemporal Lobe Epilepsy (TLE)Milner (1958, 1962): Patients undergoing unilateral temporal lobe resection for relief of intractable complex partial seizuresTemporal lobectomy: Anterior portion (5cm) of temporal lobe removed including the anterior portion of the hippocampusMemory Disorder: Material specific not modality specific
11Left 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
14TLE – Case Example Case: KE Age: 19 years Sex: Female History: 6 month history of complex partial seizuresEduction: HSC graduate, Commenced first year of a degree in PE teaching – deferred due to memory problems
22Material Specific Disorders of Memory (con’t) 2. Cerebrovascular DisordersDisruption 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 disorderUnilateral thalamic infarction (secondary to PCA disturbance) may also produce a material specific disorder of memory.
23Specific Disorders of Memory Topographical disorientationDamage to the right tempero-parietal areas (MCA)Unable to find way around.Tactile MemoryImpairment reported in patients with unilateral temporal lobe lesion resulting from CVA with loss demonstrated in hand contralateral to the lesion.
24BS: Lateralised (R.Hem) Dysfunction 45 yo female9 years educationDSS (clerical) for 17 years3-4 months preceding ABI worked as a taxi driver1/1/02 assaulted during the course of her workPTA: several days duration (no recollection of visitors while in hospital, son receiving HSC results)
25CT (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 PTSDPsychiatrist noted that she intermittently complained of memory problems and geographical disorientation
26Case BD Assessment February 2007 Attended unaccompanied Fully cooperativec/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
27WAIS-IV Verbal IQ = 116 PIQ = 110 Working Memory = 117 Processing Speed = 104Full Scale IQ = 111General Ability = 113
28WMS-IV INDEX ACTUAL PREDICTED Auditory Mem 103 106 Visual Mem 75 Visual Working Mem108107Immediate Mem_Delayed Mem
31BD: Adaptive Abilities and Emotional Status Trail Making TestPart A = 26 seconds, 0 errorsPart B = 50 seconds, 0 errorsControlled Oral Words Association Test (COWAT)Words = 45, Errors = 3Wisconsin Card Sorting TestCategories = 6, Errors = 12Perseverative Responses = 6 (Above Average)Booklet Category TestErrors = 107 (Impaired)Depression, Anxiety, Stress ScalesDepression = 40 (Ex.S.),Anxiety = 36 (Ex.S.), Stress = 32 (Ex.S.)
32BD: OpinionThe 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.
33Neither 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.
34BD: Opinion (con’t)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.
35BD: Opinion (con’t)On a day to day level BD’s 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
36compromised 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.
39Frontal Amnesia A. Organisational Deficits Simple registration and recall not affected by frontal lesionsMemory problems may be secondary to an inability to organise material for the purpose of committing it to memoryi.e. failure to impose a meaningful structure on the information, to generate appropriate learning strategiesFrequent concomitant of traumatic brain injuryManifest on tests such as Rey Complex Figure, Rey Auditory Verbal Learning
42Frontal Amnesia B. Retrieval Problems Retrieval involves strategic problem-solving. Often disturbed following frontal lesionsPatient with a retrieval deficit will demonstrate a disturbance of free recallRecognition memory should, however, be intacteg. RAVLT: poor score on recall of list A (trials 1-6)recognition 15/15One advantage of WMS-III relative to WMS-R
43Frontal Amnesia C. Temporal Discrimination Increasing attention being devoted to this aspect of memoryPatients 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 pathologyTwo processes involved:Encoding of information needed for temporal memoryEffective processing of retrieved information regarding temporal orderIn 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)).
44General Amnesic Syndrome DefinitionA 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. PermanencyStabilityPervasivenessSpecificity
45Clinical Features of the Amnesic Syndrome Profound difficulty or total inability to acquire new material (anterograde amnesia)Preservation of immediate memory as measured by tasks such as digit spanPreservation of semantic memoryPreservation of procedural learningSome retrograde amnesia (variable across patients)
46Neuopathology Brain structures implicated: Bilateral damage to the mesial temporal lobes of both the right and left hemispheresWithin these areas the hippocampus has been seen to represent the crucial structure2. Structures within the diencephalon and specifically:Nuclei within the thalamusMamillary bodiesMamillo-thalamic tractFornixAll above structures represent part of the limbic system
48Aetiology GAS typically seen in association with Wernicke-Korsakoff SyndromeHerpes Simplex EncephalitisHypoxiaAnterior Communicating Artery AneurysmThalamic InfarctionTemporal Lobe ResectionOther causes:CVATumour
50Wernicke-Korsakoff Syndrome Typically the result of chronic alcoholismPrinciple cause: Thiamine deficiencyResults in damage to the subcortical structures and in particular the diencephalonMinimal requirement: Lesion of the mamillary bodies and dorsomedial nucleus of the thalamusTypically additional lesions in the frontal lobes (atrophy) due to alcohol neurotoxicity and often the medial temporal structures including the hippocampusTreatment. Thiamine. Amnesia often persists
51WKS: Characteristics Normal memory span Severe anterograde amnesia Normal rate of forgettingExtensive, temporally graded retrograde amnesiaConfabulation presentCued recall better than spontaneous recallRecognition relatively intactPoor at recency judgementsFrontal lobe dysfunction typically present