1. DISSOCIATION BETWEEN RECALL AND RECOGNITION MEMORY IN AMNESIA: The case of a patient with hippocampal damage following carbon monoxide poisoning Christine BASTIN 1, Martial VAN DER LINDEN 1,2, Annik CHARNALLET 3, Christine DENBY 4, Daniela MONTALDI 4, Neil ROBERTS 5, & Andrew MAYES 4 1 Department of Cognitive Sciences, University of Liège, Belgium; 2 Cognitive Psychopathology Unit, University of Geneva, Switzerland; 3 University Hospital of Grenoble, France; 4 Department of Psychology, University of Liverpool, U.K.; 5 MARIARC, University of Liverpool, U.K. Introduction There are currently two opposing views regarding the status of recall and recognition memory in amnesia: - Recall and recognition memory are measures of declarative memory, which depends on the integrity of the medial temporal lobe (MTL) and diencephalic structures 1. Evidence: proportionate deficits of recall and recognition memory in amnesic patients following damage to the MTL, even when limited to the hippocampus. - Two systems: (a) hippocampal system (hippocampus, fornix, mamillary bodies, anterior nuclei of thalamus): crucial for associating the components of an episode and involved in recall and recollection-based recognition; (b) perirhinal cortex-medial dorsal thalamus system: supports familiarity-based recognition 2. Evidence: in amnesic patients with damage limited to the hippocampus, impaired recall and recollection, but preserved familiarity-based recognition memory 3,4. The present study explored recall and recognition memory in a patient (MR) who became amnesic following CO poisoning, an aetiology associated with bilateral hippocampal damage. Case description -Patient MR, right-handed man, 65 y.o. -CO poisoning at age 48 -The neuropsychological examination revealed memory disorders, which have remained stable since the accident (e.g. General Memory Quotient, WMS-R: 83). In contrast, intellectual function (WAIS-R IQ: 122), visuo-spatial abilities, language, executive functions are normal. References (1) Squire, L.R., Stark, C.E.L., & Clark, R.E. (2004). The medial temporal lobe. Annual Review of Neuroscience, 27, 279-306. (2) Aggleton, J. P. & Brown, M. W. (1999). Episodic memory, amnesia, and the hippocampal-anterior thalamic axis. Behavioral and Brain Sciences, 22, 425-489. (3) Holdstock, J. S. et al. (2002). Under what conditions is recognition spared relative to recall following selective hippocampal damage in humans? Hippocampus, 12, 341-351 (4) Yonelinas, A. P. et al. (2002). Effects of extensive temporal lobe damage or mild hypoxia on recollection and familiarity. Nature Neuroscience, 5, 1236-1241. (5) Baddeley, A. D., Emslie, H., & Nimmo-Smith, I. (1994). Doors and People : A test of visual and verbal recall and recognition. Bury St. Edmunds, England: Thames Valley Test Co. (6) Bastin, C. & Van der Linden, M. (2003). The contribution of recollection and familiarity to recognition memory: A study of the effects of test format and aging. Neuropsychology, 17, 14- 24. (7) Jennings, J. M. & Jacoby, L. L. (1997). An opposition procedure for detecting age-related deficits in recollection : Telling effects of repetition. Psychology and Aging, 12, 352-361. Christine Bastin is a post-doctoral scientific collaborator of the National Funds for Scientific Research (FNRS), Belgium. Discussion - MR presents with a dissociation between recall and recognition memory. His recall performance is more dramatically impaired than his recognition performance. This was observed on verbal as well as non-verbal materials, and when recognition memory was at least as difficult as recall (Calev’s procedure, Doors and People test). - Evidence for impaired recollection and relatively preserved familiarity. - This pattern was observed in the context of bilateral atrophy of the hippocampus, despite parietal and temporal lobe atrophy. - These data support the 2-system point of view, suggesting that the hippocampus is crucial for recall and recollection, but not for familiarity. Bilateral volume reduction of the hippocampus, and intact appearance of the perirhinal cortex. Frontal lobes are normal. 1. Verbal recall and recognition memory. Calev’s matched-task procedure Verbal recall: study of 24 words from 6 semantic categories, presented for 4 s each, blocked by category, followed by free recall. Verbal recognition: study of 40 unrelated words, presented for 4 s each. Then, recognition test: the 40 target words and 40 distractor words are presented in random order one at a time. The subjects must say for each item whether he has seen it or not. These tasks are of comparable levels of difficulty. Magnetic resonance imaging examination (volumetric analysis) Atrophy of the parietal and temporal lobes and the hippocampi. The volume of the hippocampus is reduced by 57% on the right and 67% on the left. Experimental investigations 2. Non-verbal recall and recognition memory. Doors and Shapes subtests from the Doors and People test 5 Shapes (recall): study of 4 simple line drawings, immediate free recall (max. 3 trials if not correct) and delayed recall. Doors (recognition): study of 12 photographs of doors, and recognition of the studied doors in a four-alternative forced-choice test. Set A: the distractor doors are relatively different from the target door. Set B: the distractor doors are very similar to the target one. MR’s recall is severely impaired, whereas his recognition memory is within the normal range. MR’s deficit on recall of the Shapes is much more severe than his deficit on recognition of the Doors (t(17) = 3.41, p <.01). On the set A, MR’s recognition memory was normal, but it was impaired on set B. 3. Yes/no and forced-choice recognition memory. Forced-choice task: study of 18 unfamiliar faces, 1.5 s per face; recognition test: 18 target-distractor pairs (which one has been presented?) Yes/no task: study of 18 unfamiliar faces, 1.5 s per face; recognition test: 18 target + 18 distractor faces presented one at a time (seen or not?) Previous work has showed that familiarity is recruited to a greater extent by the forced-choice task than the yes/no task 6. Preserved recognition memory. MR tended to perform better on the forced- choice task than on the yes/no task. 4. Process-dissociation procedure 7. Inclusion condition: Study: 40 words, 3 s each; Test: 40 targets + 40 distractors, repeated either immediately, after 3 intervening items or after 12 intervening items; yes/no recognition: say “yes” to all items that have been seen at least once before (targets and repeated distractors) Exclusion condition: Study: 40 words, 3 s each; Test: 40 targets + 40 distractors, repeated at lag 0, lag 3 and lag 12; yes/no recognition: say “yes” to target items only and say “no” to distractors even when repeated. In the exclusion condition, MR said erroneously “yes” to repeated distractors more often than the controls. The computation of process estimates shows that recollection is impaired, whereas familiarity is preserved in MR.