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.
Background: Reading impairment is frequently associated with neurodegenerative diseases, such as Alzheimer disease (AD), primary progressive aphasia (PPA), and posterior cortical atrophy (PCA). Notwithstanding the clinical relevance of reading processes in these conditions, only a relatively small number of studies have been published on this topic so far.Aims: We investigated the reading impairment in patients with different types of neurodegenerative diseases. In the light of the marked variability in pathological changes affecting brain areas potentially relevant to reading, it could be hypothesised that these neurodegenerative conditions may lead to different patterns of reading impairment.Methods & Procedures: Three groups of patients (AD, PPA, and PCA) and a control sample of neurologically healthy participants were examined with five tasks to test the ability to read and to repeat words and nonwords, as well as with an auditory and visual lexical decision task.Outcomes & Results: No specific pattern emerged as strongly diagnostic of a specific degenerative disease. Overall, AD and PPA patients were significantly more impaired in reading nonwords than words. Lexical decision impairment in the visual modality appears to be related to PCA, while a similar deficit in the auditory modality is more suggestive of AD. A multiple single-case analysis on the reading performance was run to identify the distribution of different kinds of dyslexia: phonological dyslexia occurred in 50% of patients affected by PCA: it occurred less often in patients affected by AD (15.8%) and PPA (16.7%). Surface dyslexia occurred only in one case of AD. Age of acquisition was predictive of the reading performance for AD patients, but not for PCA and PPA patients.Conclusions: Phonological dyslexia predominates in PCA. Surface dyslexia occurred only in one AD patient. Reading nonwords was predominantly impaired in AD and PPA cases. Impairment in visual lexical decision was associated with PCA, whereas a lexical decision deficit in the auditory modality emerged in AD. Data indicate the importance of extensive testing of reading and input lexical abilities in neurodegenerative diseases.
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 (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.
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.
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.
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.
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.
This detailed clinical report of a typical Capgras delusion (CD) in a demented patient is presented in order to foster future descriptions in neurological cases. In the framework of a recently developed model of familiar person processing, it is suggested that CD might be due to a dysfunction at the level of Person Identity Nodes. Prefrontal impairment is held to represent a critical factor leading to a failure of belief evaluation.
Naming celebrities from visual input (i.e., face presentation) was examined in 98 healthy participants. Normative data are provided both for a 12-and a 63-item test. The first one is a brief screening tool, while the latter is to be administered whenever a pathological performance turns out in the former. Age adversely affected both performances. In both tests the most frequent errors were no responses, followed by semantic errors. The study makes explicit reference to current serial models of familiar person processing and naming. Findings allow to complement previously reported testing procedures, with the specific aim of qualifying proper name anomia by identifying the cognitive locus of lesion.
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.
Ninety-eight healthy participants were examined with a new test of Famous Name Comprehension which, in the framework of a serial model of person processing, sequentially assessed Name Recognition (i.e., the ability to classify items as familiar or unfamiliar) and Person Identification (i.e., the ability to provide biographical knowledge of recognised items). Names were presented in a written format. A perfectly equivalent face version of the test allowed a comparison of familiarity and identification of people from name and from face input. Furthermore, the effect of the "age" of the items, i.e. the time elapsed from the presumed first exposure to the stimulus to the time of testing, was also investigated. Normative data are provided. Education was the only significant variable for recognition, while education, age and gender turned out to be significant for identification. Recognition was significantly better with name than with face input, while on identification names and faces did not differ significantly. "Oldest" items were both recognised and identified significantly worse than recent ones. The results of face-name comparison are interpreted in terms of the different opportunities to be exposed to names and faces, the relevance of visuoperceptual attributes linked to faces and the evidence of shared knowledge from different inputs. The relative advantage of recent celebrities supports the semantic characterisation of knowledge of famous people.