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.

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.

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.

Gesture imitation with lower limbs following left hemisphere stroke.

Ideomotor apraxia (IMA) of lower limbs has rarely been investigated systematically. This is the aim of the current study. Thirty-five patients with a unilateral stroke in the left hemisphere were tested within 30 days from onset with an upper limb IMA test and with a newly devised test assessing leg IMA. Seventeen patients presented with arm apraxia, six of them also showed severe leg apraxia. Results suggest that IMA of lower limbs emerges in association with severe arm IMA in patients with large lesions, and is a sign of general severity of the patient's conditions.

Hemisphere asymmetry for imitation of hand and finger movements, Goldenberg's hypothesis reworked.

Goldenberg and co-workers put forward the hypothesis that coding of hand gestures with respect to body parts depends upon the functioning of the left hemisphere while the right hemisphere would be involved in imitation of finger postures. They supported this claim with experimental evidence from lesion studies, however, they failed to back it up with functional neuroimaging data. To verify Goldenberg's hypothesis on hemisphere asymmetries for hand/finger postures imitation, the performance of 35 patients with left hemisphere lesion (L/pts), of 24 patients with right hemisphere lesion (R/pts) and that of 41 matched controls was assessed in two imitation tasks, respectively, taxing hand or finger postures. The data, adjusted for the performance of the controls and for the effect of age were analysed using a multivariate, nonparametric approach. The outcome partly supports Goldenberg and colleagues' hypothesis: hand minus finger performance did differs between the R/pts and L/pts patients, even considering the pertinent hand-finger performances by control participants, however, in line with neuroimaging evidence, the left hemisphere's contribution is greater than that of the right for both finger and hand posture imitation.

A new account of face apraxia based on a longitudinal study.

The aim of this paper is to provide an interpretation of face apraxia which accounts also for the role of right hemisphere lesions. Thirty-one patients with left hemisphere (L/pts) and 31 patients with right hemisphere (R/pts) lesions entered a cross-sectional study to identify those presenting with either lower or upper face apraxia. The 16L/pts and 8R/pts who presented with face apraxia in the acute stage and could be retested 4 months later, were followed up longitudinally. The degree of recovery did not differ between the two groups of patients. The traditional hypothesis of face apraxia based on the presence of a left-sided praxis centre could not account for these findings. A new trade-off model of face praxis resources distributed across the two hemispheres is presented. This model, based on individual differences in the healthy brain, accounts for the presence and persistence of face apraxia in a proportion of R/pts.

[Dementias: mostly clinico-neuropsychological or mostly psychometric diagnosis?]. / Demenze: diagnostica prevalentemente clinico-neuropsicologica o prevalentemente psicometrica?

In this paper many critical reflections on diagnosis management of patients affected by dementia have been reported. In particular, the importance of clinico-neuropsychological evaluation of patients with respect to management prevalently based on neuropsychological tests is underlined. In this view a periodic diagnostic exercise with the objective of improving the diagnostic approach of dementias has been proposed to the Alzheimer's disease units (UVA) included in the Cronos Project.

The role of semantic knowledge on the cognitive estimation task--evidence from Alzheimer's disease and healthy adult aging.

The current study investigated the role of semantic knowledge on the Cognitive Estimation Task (CET). In an initial experiment, the CET performance of 21 patients with frontal lobe lesions was compared with 21 healthy controls. The CET was found to be sensitive to the effects of frontal lobe lesions. In Experiment 2, 175 participants aged between 18 and 87 years performed the CET to examine the effects of healthy adult aging on the task. No significant age effects were evident. In Experiment 3, 27 patients with Alzheimer's disease (AD) were compared with 27 healthy controls on the CET. AD patients produced significantly more extreme cognitive estimates than the controls. A significant correlation was found between CET performance and performance on the General Knowledge of the World Task, a task intended to assess semantic knowledge. The hypothesis is put forward that healthy older adults are able to use their intact semantic knowledge to compensate for problem-solving deficits when generating cognitive estimates. In contrast, owing to degradation in semantic abilities, AD patients are unable to benefit from semantic knowledge and instead tend to produce bizarre cognitive estimates.

Upper and lower face and ideomotor apraxia in patients with Alzheimer's disease.

INTRODUCTION: Apraxia of face movement in Alzheimer's disease (AD) has been rarely investigated. This study aimed at investigating the frequency of lower (mouth, tongue and throat) and upper (eyes and eyebrows) face apraxia, in AD and its relationship with limb apraxia and severity of dementia. METHODS: Fifty seven patients with AD were tested with a new standardised test of face apraxia including upper and lower face movements, which uses an item-difficulty weighted scoring procedure, the IMA test, a test of ideomotor apraxia and the M.O.D.A., a means to assess dementia severity. RESULTS: Thirteen (23%) and 19 (33%) participants were below cut-off respectively on the upper and lower face apraxia test. Both sections of the Face Apraxia Test correlated significantly with the Ideomotor Apraxia Test. However, double dissociations between different types of apraxia were observed. Both the upper and lower face apraxia tests correlated significantly with the measure of dementia severity. CONCLUSIONS: The finding show that a proportion of AD patients fails face apraxia tests. Their face apraxia is interlinked with ideomotor limb apraxia, although dissociations are possible. Severity of dementia deterioration accounts for a good proportion of the variability of AD patients' performance on face apraxia tests.

Covert person recognition: its fadeout in a case of temporal lobe degeneration.

Covert person recognition was investigated longitudinally over a three-year period in a patient suffering from "Crossmodal Familiar Person Agnosia", possibly due to a fronto-temporal dementia in its right temporal variant (Gentileschi et al., 2001). The progressive neuronal degeneration in the cortical regions critical for face recognition (viz., right infero-temporal areas) presented us with the opportunity to check Burton et al.'s (1991) and Farah et al.'s (1993) hypothesis on the dissociation between overt and covert face recognition in a neuropsychological condition which, however, is neurologically and cognitively different from that of focal "associative prosopagnosia". Covert person recognition starting from overtly unrecognised faces was assessed by means of learning tasks of face/name association involving celebrities. It was assumed that some unconsciously spared information would selectively enhance the relearning rates when famous faces were paired with their true names. In fact, the true-name advantage (i.e., selective saving for experimental relearning of true name pairings) reached significance at first assessment, carried out five years from clinical onset. Effect faded away two and three years later on, thus abolishing the overt/covert dissociation in face recognition. These findings support Burton et al.'s (1991) and Farah et al.'s (1993) hypothesis of covert face recognition as the consequence of partial and incomplete activation of person semantics, due, in the present case, to the impoverishment of Gentileschi et al.'s (2001) "exemplar semantics" storehouse. Moreover, it turned out that covert recognition does not imply a different learning slope, but an overall different level of the learning profile.

Utilisation behaviour consequent to bilateral SMA softening.

The case of patient CU, who presented with severe utilisation behaviour, eventually unaccompanied by psychometric signs of frontal involvement, is reported. He suffered from a bilateral stroke within the territory of the anterior cerebral artery. His arterial system was characterised by a unique variant, whereby the right anterior cerebral artery was missing and three trunks originated from the left anterior cerebral artery, each bifurcating into right and left branches. An occlusion of the middle trunk immediately before its partition gave rise to a symmetrical bilateral parasagittal lesion that damaged the supplementary motor areas (medial part of Brodmann's area 6), sparing the lateral regions including the premotor cortices, the corpus callosum and the gyri cinguli. The hypothesis is put forward that utilisation behaviour should be conceived as a double anarchic hand, and its interpretation should rest on the damaged balance between the premotor cortices, responsive to environmental triggers, and the supplementary motor areas, which modulate actions and inhibit them. The imbalance due to the lesion would result in the patients being left at the mercy of environmental stimuli, unable to inhibit inappropriate actions. This intra-frontal hypothesis accounts for the data presented and those from the literature better than the previously held fronto-parietal equipoise.