n Syndromes leading to Organic Amnesia u Wernicke-Korsakoff syndrome u Alzheimer’s u Anoxia, tumors, accidents, everything that damages or blocks the blood flow to certain regions n What regions? u Medial temporal lobe u Basal forebrain F Medial diencephalon F Frontal lobes
Tracelink Modeling consolidation and amnesia M Meeter
The TraceLink model
Simulation model n Stochastic neurons, firing likelihood determined by input and inhibition n Both layers connected to itself and each-other n Hebbian learning n Patterns consist of a random collection of trace nodes and link nodes
Scheme of a simulation n Learning phase: acquisition of 15 patterns n After acquisition of a pattern, 3 consolidation trials n Consolidation: one random attractor strengthened
Simulated with TraceLink n Retrograde amnesia with Ribot gradient (damage to link structures) n Anterograde amnesia correlated with RA (damage to link structures) n Anterograde amnesia without RA (damage to modulatory structures) n Temporary amnesia (TGA) (hypo-perfusion of link structures) n Isolated retrograde amnesia (damage to trace-link connections) n Implicit memory in amnesia n Consolidation of arousing stimuli n Levels of processing n Semantic dementia (damage to trace connectivity)
Simulating retrograde amnesia through a lesion of the link system
Simulating semantic dementia through diminished trace connectivity
Empirical claims n Lesions to link structures (e.g., medial temporal lobe) produce u correlated AA and RA, with u the RA showing a Ribot gradient n Discrete lesions to modulatory structures (e.g., basal forebrain) produce AA without RA n Lesions involving both the link and modulatory system produce lowly correlated AA and RA n Only strong patterns are consolidated
Meten & vergeten Meetinstrumenten voor retrograde amnesie
Two forms of amnesia
Measuring retrograde amnesia (RA) RA can only be measured indirectly, by comparing memory of patient with what is normal u Items must assess memories that every respondent has u Items must be dateable: it must be clear which period is assessed
Three test types n Public events tests u AMV: Amsterdamse Media Vragenlijst u DNMT: Daily News Memory Test n Autobiographical tests u AGI: Autobiografisch Geheugeninterview n Vocabulary tests u NVT: Nieuwe Vocabulairetest
Public events tests I n Amsterdamse Media Vragenlijst u I.c.w. Paulien Klomps & Denny Borsboom u Questions from ’70s, ’80s and ’90s, that at least 70% of controls have correct u Has been tested on normal controls n Example from ’70s: u Waardoor komt het Drentse plaatsje Beilen in december 1975 in het nieuws?
Public events tests II n Daily News Memory Test (in prep.) u I.c.w. Steve Janssen & Jaap Murre u Available on internet (http://memory.uva.nl) u Questions about news events u Selected from daily expanding database n Example from Feb. 9 th u NL: tegen wat botste de Amerikaanse onderzeeer USS Greeneville op 9 februari? u Int.: with what did the American submarine USS Greeneville collide on February 9, 2001?
Autobiographical Tests n AGI, Autobiografisch Geheugeninterview u I.c.w. Jaap Murre u Adaptation from AMI (Kopelman, Wilson & Baddeley, 1989) u Questions about life events u Is being tested in normal controls n Example (recent period): u Waar heeft u het afgelopen jaar kerstmis gevierd?
Vocabulary test n Nieuwe Vocabulaire Test (in prep.) u I.c.w. Eveline de Wilde u Consists of neologisms from ’70s, ’80s and ’90s u Participant has to define the neologisms, and later choose correct definition from 3 distracters n Example (’90s): u Wat betekent Euro
Goals of the battery n Practical goals u Offer doctors tests for retrograde amnesia that may be helpful in diagnosis u Developing memory test portal for neuropsychologists n Theoretical goals u Open up Dutch amnesic populations for research on retrograde amnesia u Characterize remote memory in given patient populations in precise ways u Test for Ribot gradients on short time scales in patients with limited retrograde amnesia.