Degenerative Amnesia for Past Public Events: An Attempt to Measure Storage and Retrieval.

A still unsettled issue of amnesia concerns the differential contributions to recall impairment of the underlying retrieval and storage abilities. The aim of the present study was to disentangle and to measure such roles in the recall of past public events comparing patients with degenerative amnesia and healthy elderly. The experiment included 44 healthy elderly and two groups of participants with degenerative amnesia, namely 17 patients with amnestic mild cognitive impairment and 22 mild Alzheimer's disease patients. Recall of famous past public events was assessed by means of a 52-item questionnaire standardized for the Italian population. A latent-variable approach was adopted in order to infer the contributions of retrieval and storage to the recall performances. A stochastic model was adopted, which in a previous study of recall of recent and remote past public events in healthy elderly succeeded to prove reduced retrieval efficiency for more recent events. The results of the present study suggest that retrieval is more fragile than storage in all three experimental groups. A storage impairment turned out only in the Alzheimer's disease group, where it was limited to more recent memories. In view of the combined roles of the hippocampus and cortex in past memory processing, our results are consistent with the hypothesis that the degenerative process primarily impairs the strategic memory search. However, the sufficiency criterion of the adopted Markov model fell short of significance. Due to this statistical shortcoming, our conclusions, though consistent with the clinical predictions, are to be taken as provisional.

Long-term proper name anomia after removal of the uncinate fasciculus.

A previous study reporting on 44 patients who underwent awake surgery for a left frontal or temporal glioma resection demonstrated the removal of the uncinate fasciculus to have consequences on language 3 months post-surgery. At this time-point, patients with a temporal glioma who had undergone uncinate removal showed the worst overall performance with a significant impairment in naming of famous faces and objects compared to patients without removal. Also, verbal fluency was mildly impaired. We report a longer-term follow-up (9-12 months) in a selected group of 17 patients (six female, age range 27-64) who did not suffer any tumour recurrence in this timeframe. MRI and DTI were performed before and after surgery. While verbal fluency on categorical cue and object naming recovered to the same level as before surgery, proper naming remained significantly impaired even after 12 months (P = 0.032) in patients with uncinate removal, demonstrating this structure to be crucial for that function and supporting the hypothesis that subcortical connectivity is relevant to allow plasticity. We thus argued that the left frontal and temporal poles connected by means of the uncinate fasciculus constitute a dedicated circuit for naming of unique entities.

Autobiographical memory in amnestic Mild Cognitive Impairment.

Autobiographical memory (ABM) was evaluated in 19 patients with amnestic Mild Cognitive Impairment (aMCI) by means of the standardized enquiry developed by Borrini et al. (Psychol Med 19:215-224, 1989). Longitudinal assessments were carried out by re-testing participants at 9-month intervals up to three assessments over 18 months. Although aMCI patients performed significantly worse than age-, gender- and education-matched normal controls, all of them achieved above normal scores according to Italian norms. No evidence of disproportionate sparing of remote memories (i.e., classical temporal gradient, TG) was found. These findings contrast with the previously reported significant impairment of memory for public events (Bizzozero et al. in J Clin Exp Neuropsychol 31:48-56, 2009). Such a discrepancy might be attributed to the adopted ABM enquiry tapping "personal semantics", presumed to rely largely on prefrontal functions, in contrast with the mainly episodic qualification of memory for past public events, which is mostly dependent on hippocampal structures. Our results also support the hypothesis that the contents of remote memory archives may be differentially affected in aMCI.

Ambiguous idiom comprehension in Alzheimer's disease.

Ambiguous idiom comprehension was examined in 15 patients with mild probable Alzheimer's disease (AD) by means of two tasks: a string-to-picture matching task and a string-to-word matching task. In the first, patients had to choose among four pictures, while in the second they chose among four words. For both tasks the alternatives were the picture/word corresponding to the figurative meaning, a semantic associate (picture/word) to the last word of the idiom, and two unrelated alternatives, which were, in the case of words, an unrelated foil preserving the semantic class and a literal continuation foil (a word that can follow the verb in that sentence), while in the case of pictures the first was substituted by an unrealistic foil. The patients were also submitted to three language, one visuo-perceptual, and two executive tasks. Idiom comprehension was poor, particularly when the string-to-picture matching task was used, and correlated with executive tests. We confirm that linguistic and extralinguistic factors must be taken into account to explain ambiguous idiom interpretation, and we underline the role of the testing modality in the case of pathological populations.

Mild cognitive impairment does entail retrograde amnesia for public events.

In this study memory for public events was evaluated in 15 amnesic mild cognitive impairment (aMCI) patients, whose clinical diagnosis was refined through a stringent selection procedure. A total of 9 patients were longitudinally reassessed over an 18-month period. About half of the participants were impaired at baseline and nearly 80% at the end of the 18-month follow-up. Moreover, retrograde memory declined significantly over time. Evidence of a pathological Ribot-type temporal gradient was found in about half of the aMCI patients. This is the first report of a remote memory deficit in aMCI. It highlights amnesia for public events as a frequent accompaniment of this condition. The findings tie in with the hypothesized role of the hippocampal complex in long-term memory.

Recollection of public events in healthy people: a latent-variable stochastic approach to disentangling retrieval and storage.

Recollection of media-mediated past events was examined in 96 healthy participants to investigate the interaction between the age of the subject and the "age" of memories. The results provided evidence that people older than 75 years recall recent events significantly worse than remote ones. Younger participants (47-60 years old) showed the reverse pattern. The implementation of a Markov chains latent-variable stochastic model suggested that reduced efficiency of retrieval rather than storage processes accounts for these results. The findings were interpreted with reference to models of memory trace consolidation, assuming that memory for past public events is dependent on hippocampal structures.

A reappraisal of person recognition and identification.

In the last years an increasing number of cases (Gainotti et al., 2008, this issue) have been reported in whom difficulty to recognise and identify familiar people occurs in everyday multimodal settings, differently from unimodal face-specific impairments (i.e., prosopagnosia). A reappraisal of current person processing models is presented in order to account for such deficits as well as for the common slips of recognition occurring in healthy subjects. The model we propose is based upon three main modifications of current models, namely: (1) the role of PINs as stores of multimodal perceptual knowledge; (2) the richness of perceptual nuances characterizing PINs of most familiar people; (3) the PINs' addressing of Exemplar Semantics by a provisional Gestalt guessing and an analytical check, to be negotiated whenever a conflict arises. A single case report of Capgras delusion is presented as a crossmodal person processing disorder in everyday settings for whom the proposed model allows a cognitive interpretation.

Phonological recoding, visual short-term store and the effect of unattended speech: evidence from a case of slowly progressive anarthria.

Phonological processing and short-term memory were investigated in a patient with slowly progressive anarthria. The patient, who had an auditory-verbal span in the lower unimpaired range, showed preserved phonological similarity and word length effects with auditory presentation. These phonological effects of immediate retention were absent with visual input. The patient was also unable to perform phonological judgments on written verbal material. Under unattended speech interference her visual span improved, with an increase of visual confusion errors. In the light of a model including a main auditory-verbal storage component (the phonological short-term input store, STS), and a rehearsal process, that, after phonological recoding, conveys visually presented verbal material to the phonological STS, the patient's pattern of impairment is interpreted as a selective deficit in the process of phonological recoding. This prevents visual-verbal material from accessing the phonological STS, that is, therefore, insulated from visual inputs.

Is slowly progressive anarthria a "pure" motor-speech disorder? Evidence from writing performance.

It is usually assumed that writing is normal in patients with anarthria, but a careful examination of the literature shows that they produce deletions, transpositions and insertions. Indeed, a matter of debate concerns the distinction between primary progressive aphasia (PPA) and slowly progressive anarthria (SPA). If writing deficits were purely linguistic errors, then there would be no reason to consider slowly progressive anarthria as distinct from non-fluent PPA. We report the case of a patient with SPA in whom writing abilities were specifically assessed. No lexical-semantic deficits were detected, but errors were deletions, substitutions or transpositions, with no frequency, length or lexicality effect; moreover, controls produced the same kind of errors during articulatory suppression. It is suggested that subvocal rehearsal plays a role in writing, allowing the conversion/assembly of the phonological string in a graphemic representation. Therefore, writing deficits do not appear to have a linguistic basis and SPA seems distinguishable from nonfluent forms of aphasia.

Idiom comprehension in Alzheimer's disease: the role of the central executive.

Idiom comprehension of 15 patients with mild probable Alzheimer's disease was examined by means of a sentence-to-picture matching task. Patients had to choose between two pictures, one representing the figurative and the other the literal interpretation. They were also submitted to a literal sentence comprehension test and to a pencil-and-paper dual task. Whereas literal comprehension was normal in seven subjects and mildly impaired in the others, idiom comprehension was very poor in all of them and correlated with the performance on the dual task. When the idiom test was repeated using an unrelated situation as an alternative to the picture representing the figurative meaning, performance significantly improved. It was hypothesized that the response in the sentence-to-picture matching task in the case of idioms requires sentence processing followed by the suppression of the literal interpretation. Alzheimer's disease patients proved to be unable to inhibit the literal meaning, although they had not lost the idiomatic meaning. In a second experiment, 15 Alzheimer's disease patients with a comparable level of cognitive impairment were submitted to the same idiom comprehension test, and to a test of verbal explanation of the idioms. The results showed significantly better performance in the oral task than in the sentence-to-picture matching task. In oral explanation, however, Alzheimer's disease patients also produced some literal interpretation whenever this represented a possible situation in the real world. We suggest that, during idiom interpretation, the literal meaning needs to be suppressed in order to activate the figurative meaning, and we stress the fact that both linguistic and extralinguistic factors must be taken into account to explain idiom interpretation.