Maria Cristina Saetti

Associative agnosia and optic aphasia: qualitative or quantitative difference?

We report a patient who, following the partial removal of a tentorial meningioma, suffered a hematoma in the left occipital lobe, which was resected. He showed severe anomia for visually presented stimuli, while naming was normal when they were presented in the tactile, auditory and verbal modality. His performance on visuo-perceptual tests, not requiring meaning identification, provided evidence that he was able to access the stored representations of stimuli. When recognition was assessed with non-verbal tasks, a mixed pattern of findings emerged and the patient showed features of both associative agnosia and optic aphasia. He was severely impaired in producing pantomimes in response to pictures, but only marginally impaired in sorting figures from the same superordinate category into fine-grained subcategories. He performed within the normal range on an associative task, in which the distractors bore no semantic relation to the target, but made many errors when the distractors and the target were semantically related. We propose that the interpretation advanced by Coslett and Saffran (Brain, 1989) for optic aphasia also holds for associative agnosia and argue that both syndromes reflect the impaired access of structured representations to left hemisphere semantics, but differ in terms of the degree of compensation provided by the semantic resources of the right hemisphere. Since the anatomical basis of the two syndromes may be very similar, we submit that what makes the difference is the semantic potential of the patients right hemisphere.

Learning and forgetting processes in Parkinson's disease:: A model-based approach to disentangling storage, retention and retrieval contributions

Learning and forgetting a prose passage was studied in 20 patients with Parkinsons disease and in 20 normal control subjects by means of stochastic models, with the aim of identifying the learning and retaining abilities that are affected by Parkinsons disease. Results suggested that Parkinsons disease patients are impaired in developing automatic processing both during learning and retaining, while functions that require active attention are spared. The automatic/intentional dissociation, which is the hallmark of motor disturbance in Parkinsons disease, extends to memory abilities, and, on the grounds of neuroanatomical, neurochemical and neurophysiological correlates, suggests that the memory deficit in Parkinsons disease may be contingent on a dysfunction of the medial prefrontal-cingulate cortex.

The nature of the disorder underlying the inability to retrieve proper names.

Two patients with the syndrome of proper name anomia were investigated. Both patients were only able to produce around 50% of the names of contemporary celebrities, but performed significantly better on a task calling for naming of historical figures. The names of relatives and friends were spared in one patient, while the other retrieved names of people known since childhood much better than those of people familiar to him since the age of 25. Geographical names, names of monuments and masterpieces were preserved. The above dissociations are taken to imply that in moderately impaired patients, a temporal gradient effect concurs to modulate the severity of the naming block. A similar impairment was found in both patients when they attempted to retrieve or relearn familiar telephone numbers. This finding suggests that the core of the disorder resides in the inability to gain access to words used to identify a single entity, regardless of whether they belong to the class of proper or common names.

Mirror asymmetry of Category and Letter fluency in traumatic brain injury and Alzheimer's patients

In this study we contrasted the Category fluency and Letter fluency performance of 198 normal subjects, 57 Alzheimers patients and 57 patients affected by traumatic brain injury (TBI). The aim was to check whether, besides the prevalence of Category fluency deficit often reported among Alzheimers patients, the TBI group presented the opposite dissociation. According to some recent claims, in fact, the deficit of TBI would be equally severe for both fluency types. The inquiry followed different approaches for data analysis, including the evaluation of a unique index (Fluency Type Index or FTI), independent of the overall fluency and aimed at expressing at individual subject level the relationship between Category and Letter fluency. The results confirmed that Alzheimers patients are more defective on Category than Letter fluency, and also clearly indicated that an opposite pattern applies to TBI patients. TBI seems to cause a relatively more severe impairment of Letter than Category fluency, probably due to its impact on the frontal lobe structures. We discuss whether, on the basis of the statistical distribution of our data, it is worth considering as homogeneous populations broadly defined groups as Alzheimers or TBI patients.

Who is who: Italian norms for visual recognition and identification of celebrities

Age-, education- and sex-adjusted norms are provided for two new neuropsychological tests, namely (i) Face Recognition (guess of familiarity) and (ii) Person Identification (biographical contextualisation). Sixty-three pictures of celebrities and 63 of unknown people were selected following two interwoven criteria1: the realm of their celebrity (i. e., entertainment, culture and politics) and the period of celebrity acquisition (i. e., pre-war, post-war and contemporary). Both media- and education-dependent knowledge of celebrity were considered. Ninety-eight unpaid healthy participants aged between 50 and 93 years and with at least 8 years of formal education took part in this study. Reference is made to serial models of familiar face/persons processing. Recognition is held to tackle the activity of Personal Identity Nodes (PINs) and identification of the Exemplar Semantics Archives. Given the seriality of the reference model, the Identification Test is embedded in the Recognition test. This entailed that only previously recognised faces were employed to achieve norms for identification.

What do you know about Ho Chi Minh? Italian norms of proper name comprehension.

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.

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.

Tactile morphagnosia secondary to spatial deficits

A 73-year old man showed visual and tactile agnosia following bilateral haemorrhagic stroke. Tactile agnosia was present in both hands, as shown by his impaired recognition of objects, geometrical shapes, letters and nonsense shapes. Basic somatosensory functions and the appreciation of substance qualities (hylognosis) were preserved. The patients inability to identify the stimulus shape (morphagnosia) was associated with a striking impairment in detecting the orientation of a line or a rod in two- and three-dimensional space. This spatial deficit was thought to underlie morphagnosia, since in the tactile modality form recognition is built upon the integration of the successive changes of orientation in space made by the hand as it explores the stimulus. Indirect support for this hypothesis was provided by the location of the lesions, which could not account for the severe impairment of both hands. Only those located in the right hemisphere encroached upon the posterior parietal cortex, which is the region assumed to be specialised in shape recognition. The left hemisphere damage spared the corresponding area and could not, therefore, be held responsible for the right hand tactile agnosia. We submit that tactile agnosia can result from the disruption of two discrete mechanisms and has different features. It may arise from a parietal lesion damaging the high level processing of somatosensory information that culminates in the structured description of the object. In this case, tactile recognition is impaired in the hand contralateral to the side of the lesion. Alternatively, it may be caused by a profound derangement of spatial skills, particularly those involved in detecting the orientation in space of lines, segments and complex patterns. This deficit results in morphagnosia, which affects both hands to the same degree.

What do you remember about Chernobyl? A new test of memory for media-mediated events

Abstract.We devised a new test for assessing remote memory for media–mediated events, i.e. events that are reported by and known through the media. The test consists of a verbal questionnaire covering famous events that occurred over a long period of time, from 1976 to 2000, specifically designed for use with the Italian population. A free recall procedure was adopted which makes use of progressive cues. The test can be easily updated for inclusion of future events. Normative and testretest reliability data are presented. The test provides a new tool for assessing media–mediated memory whenever an extensive assessment of retrograde memory performance is required, both in normal people and in brain–damaged patients.

Whose face is this?: Italian norms of naming celebrities.

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.