Paper introduction: 9/25/2012

Source monitoring in Alzheimer's Disease. Brain and Cognition 2012

Transcript

1. Source monitoring in Alzheimer’s Disease Haj, Fasotti, and Allain Brain and Cognition 80 (2012) 185-191 Paper introduction on lab meeting 9/25/2012 Presented by Tzling Liu
2. Source monitoring • The idea of source monitoring  memory re-construction than memory representation • There are three kinds of source monitoring – Reality monitoring – External source monitoring – Internal source monitoring • Neural substrates involve in source monitoring – Medial Temporal Lobes – Prefrontal cortex – Parietal Cortex and other posterior brain areas
3. AD patients in source monitoring • Introduction to AD – Introduction to AD: http://ppt.cc/Bd0H – AD patients are known to have progressive brain damage, which predominantly affects temporoparietal regions at the early stages of the disease, whith more temporal neocortex damage as the disease procresses – Frontally dysfunctioning in AD patients is thought to be related to their source monitoring failures
4. AD patients in source monitoring • Source monitoring of AD patients – Reality Monitoring • AD patients have difficulties attributing words to sources of self- and others-generated sentences – External Monitoring • AD patients were found to be intact in external monitoring – Internal Monitoring • AD patients have no difficulty distriminating materials self- generated or self-read • Significant correlations was found between source monitoring and executive function in elders and AD patients
5. Method • Participants – AD patients (mild stage of demential, MMSE score 21- 26) – older normal (matched in age and social cultural level with AD patients, MMSE score 26-30) – young adults • Materials – 36 daily objects and their corresponding word. These objects were assigned into three sets. – Order of pairing between lists and conditions (internal/external/reality) was counterbalanced
6. Method • Procedures – Source monitoring – Executive assessment • Shifting (Plus-Minus) • Updating (2-back task) • Inhibition (Stroop task) • Spontaneous flexibility (eg. Generate as many word as possible start with P in 2 min) • Bindings D A P D
7. Results • Source monitoring • Executive assessment •Main effect of group •Main effect of condition •Marginal significant interaction (greater decline between conditions in AD)
8. Results • Correlations between source monitoring and executive function assessments • Stepwies regression – After control the affection of age and education, only the score of Stroop task significantly contributing to external monitoring (24.9%)
9. Discussion • Incongruent findings – Worse external monitoring rather than reality monitoring which was found previously – Passivity • Correlation between source monitoring and inhibition function – Listig, Hasher, and Zacks (2007) • Limit the range of information entering the focus of attention • Suppress irrelevant information from working memory • Restrain strong but inappropriate response
10. Discussion • However, the inhibition deficit does not explain failure in external source monitoring… – Shallow encoding in external task – Better to use suppression related task, e.g. directed forgetting • Overlap neural substrates in Stroop and AD – Correlation between Stroop task and left inferior frontal junction (BA6, BA44) – Mitchell et al (2008) found activation in both areas in external source monitoring task.  ventrolateral prefrontal cortex as controlling specific source features during encoding (Mitchell and Johnson, 2009)