Biomedical subjects

Chris J A Moulin

Publications and source records attributed to Chris J A Moulin.

4 recordsLinked to original sources

PubMed2007

Brain function during multi-trial learning in mild cognitive impairment: a PET activation study.

We explored functional brain changes with positron emission tomography (PET) in mild cognitive impairment (MCI) patients and elderly normal controls by employing an episodic memory task that included two successive encoding trials of semantically related word-pairs and final retrieval. Both groups demonstrated significant learning across the two trials. The control group showed predominantly left frontal activity during encoding, and right frontal plus left temporal activity during retrieval. However, the MCI patients recruited partly different brain regions. They failed to activate right frontal and left temporal areas during retrieval, and failed to show any different activation for encoding on the first and second trials, whereas the controls activated a region of posterior cingulate. There was indication of compensatory increases in rCBF of the occipital cortex during incremental learning and the left frontal lobe during retrieval in the patients. These results suggest different episodic memory processing in the MCI group, and a possible over-reliance on semantic processing. Subtle functional changes occur in the pre-Alzheimer brain before there are marked structural or behavioural abnormalities.

Aged↗

PubMed2006

Diminished episodic memory awareness in older adults: evidence from feeling-of-knowing and recollection.

The ability to reflect on and monitor memory processes is one of the most investigated metamemory functions, and one of the important ways consciousnesses interacts with memory. The feeling-of-knowing (FOK) is one task used to evaluate individual's capacity to monitor their memory. We examined this reflective function of metacognition in older adults. We explored the contribution of metacognition to episodic memory impairment, in relation to the idea that older adults show a reduction in memory awareness characteristic of episodic memory. A first experiment showed that age affects the accuracy of FOK when predictions are made on an episodic memory task but not on a semantic memory task, suggesting a particular role for episodic memory awareness in metacognitive evaluations. A second experiment showed that the age-difference in episodic FOK accuracy was removed if one took into account subjective reports of memory awareness, or recollection. We argue that the FOK deficit specific to episodic memory is based on a lack of memory awareness manifest as a recollection deficit.

Adult↗

PubMed2006

Are people with mild cognitive impairment aware of the benefits of errorless learning?

Mild cognitive impairment (MCI) has been described as a memory deficit in the absence of other cognitive dysfunction. It can be thought of as a pre-clinical dementia. Memory impairment in this group is not as severe as in early dementia and thus learning is still possible. We were interested to see if errorless learning, a widely used rehabilitation technique, was of benefit to people with MCI. Since it has been shown that successful rehabilitation is somewhat contingent on awareness of function, we were also interested to see if people with MCI were aware of the benefits of errorless learning. The present study employed an errorless learning procedure on 16 people with MCI and 16 older adult controls to learn two lists of 10 words in errorless and errorful learning conditions. We adopted a metacognitive approach measuring people's memory monitoring through judgements of learning (JOLs) a prediction of future memory performance. The results revealed errorless learning is an effective memory rehabilitation tool for people with MCI, with significant increases in recall performance for both groups relative to errorful learning. Most interestingly participants were aware of the benefits of errorless learning in their JOLs. MCI participants and controls both had significantly higher JOLs for words studied under errorless learning conditions. The learning performance in MCI and theories of metacognitive awareness are discussed.

Aged↗

PubMed2002

Retrieval-induced forgetting in Alzheimer's disease.

It is claimed that Alzheimer's disease (AD) patients show reduced inhibitory processing and this has been put forward as a reason why AD patients make intrusion errors at recall. However, the evidence to date has been equivocal, because non-inhibitory mechanisms can account for the pattern of findings. Recently, however, a paradigm has been developed that is claimed to give a purer measure of inhibitory processing in episodic memory, the retrieval-induced forgetting (RIF) paradigm [Inhibitory Processes in Attention, Memory and Language, Academic Press, San Diego, 1994, p. 265; J. Exp. Psychol.: Learning, Memory Cognition 20 (1994) 1063; Psychol. Rev. 102 (1995) 68]. Thus, we were interested whether AD patients would show a deficit in inhibitory processing using this procedure. Participants studied lists of category cue-exemplar pairs (e.g. fruit-orange) then practised retrieval for a subset of items from a subset of categories before taking a final memory test for all studied items. As in previous work, inhibition was measured as the difference between final memory performance for unpractised items from practised categories, and unpractised items from unpractised categories. The results show that AD patients showed normal levels of inhibition with both tests of cued recall and category generation (CG). This suggests that a deficit in inhibitory processes during retrieval is not behind the high levels of intrusion errors made in recall in AD.

Aged↗