Biomedical subjects

Elisa Ciaramelli

Publications and source records attributed to Elisa Ciaramelli.

4 recordsLinked to original sources

PubMed2007

What are confabulators' memories made of? A study of subjective and objective measures of recollection in confabulation.

Confabulating patients claim to remember events that had not actually happened, suggesting a vivid subjective experience of false memories. The present study was aimed at examining the nature of subjective experience of retrieval in confabulators and its relation to the objective ability to recollect qualitative aspects of the original episode. In Experiment 1, 5 confabulators, 7 non-confabulating patients, and 12 control subjects studied words under shallow and deep encoding conditions and underwent a Remember (R)/Know (K) recognition task [Tulving, E. (1985). Memory and consciousness. Canadian Psychology, 26, 1-12]. For recognized words, they additionally indicated two qualitative features of the encoding context. Whereas subjective (i.e. R responses) and objective (i.e. source) measures of recollection were associated in normal controls and non-confabulating patients, they were dissociated in confabulators. In Experiment 2, participants explained the content of their R responses. We found that confabulators' recollections mainly included autobiographical information related to test items, but not to the study encounter. We conclude that remembering states in confabulators may be linked to a deficit in inhibiting irrelevant memories triggered by test items during retrieval attempts.

Adult↗

PubMed2006

Dissociating episodic from semantic access mode by mutual information measures: evidence from aging and Alzheimer's disease.

Re-thinking the semantic vs. episodic distinction with new experimental paradigms, we have designed a simple classification task to assess episodic and semantic access modes to memory for famous faces. The task requires to post 54 cards into nine mail boxes arranged in a 3x3 (nationality by field of activity) array, allowing for a quantitative analysis of the distribution of their responses, in particular of their classification errors. By using an information theoretical approach, we have developed an index of the concentration of errors, i.e. the metric content index. High levels of metric content indicate strong dependence of the classification performance on perceived relations among the set of stimuli, and therefore a preferred semantic access mode. We have found (1) a significant effect of age on the metric content, indicative of a shift from episodic to semantic access in older subjects (Experiment 1); (2) a significant correlation between the metric content and relevant measures assessing episodic and semantic retrieval mode in the Remember (R)/Know (K) paradigm introduced by Tulving [Tulving, E. 1985. Memory and consciousness. Can. Psychol. 26, 1-12] (Experiment 2); (3) a significant increase in metric content in early Alzheimer's disease patients compared to normal controls, consistent with their specific impairment in episodic access (Experiment 3).

Adult↗

PubMed2006

When true memory availability promotes false memory: evidence from confabulating patients.

We explored the extent to which confabulators are susceptible to false recall and false recognition, and whether false recognition is reduced when memory for studied items is experimentally enhanced. Five confabulating patients, nine non-confabulating amnesics--including patients with (F amnesics) and without frontal-lobe dysfunction (NF amnesics)--and 14 control subjects underwent the DRM paradigm [Roediger, H. L., & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory and Cognition, 21, 803-814.] in two experimental conditions. In both conditions participants studied eight lists of semantic associates, and free recall was tested after the presentation of each list. In the Standard condition recognition was tested after the presentation of all the lists, whereas in the Proximal condition patients were administered a six-item recognition task after the presentation of each list. Participants also provided remember or know judgements, and described the content of their recollections. All groups of patients recalled a lower proportion of targets and critical lures than did control subjects, but confabulators recalled more words unrelated to the studied lists than did NF amnesics and controls. All groups of participants improved true recognition across conditions. However, whereas normal controls suppressed false recognition to critical lures in the Proximal compared to the Standard condition, and non-confabulating amnesics showed comparable gist-based false recognition, confabulators showed increased levels of false recognition to critical lures across conditions. Furthermore, NF amnesics significantly reduced false recognition to unrelated lures in the Proximal compared to the Standard condition, whereas confabulators were unable to suppress false recognition to unrelated lures across conditions. Analysis of the phenomenological experience showed that, unlike non-confabulating amnesics, confabulators characterized true and false memories with irrelevant information related to test items. Results are interpreted in light of confabulators' monitoring deficits.

Adult↗

PubMed2006

Central executive system impairment in traumatic brain injury.

PRIMARY OBJECTIVE: This study investigated whether cognitive impairment after traumatic brain injury (TBI) can be considered a consequence of (1) a speed processing deficit or (2) an impairment of the Central Executive System (CES) of working memory. METHODS AND PROCEDURES: Thirty-seven TBI patients underwent a standardized battery of neuropsychological tests evaluating speed processing, sustained attention, short-term memory, working memory, divided attention, executive functions and long-term memory. MAIN OUTCOMES AND RESULTS: Patients showed severe deficits in working memory, divided attention, executive functions and long-term memory. Divided attention, long-term memory and executive functions deficits significantly correlated with working memory, but not with speed processing deficits. Moreover, multiple regression analyses showed that a CES impairment and not a speed processing deficit predicted divided attention, executive functions and long-term memory deficits. The severity and the site of brain lesions did not predict the level of CES or speed processing impairment. CONCLUSIONS: The cognitive impairment following TBI seem to be caused by an impairment of the Central Executive System, rather than a speed processing deficit.

Adolescent↗