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Biomedical subjects

S Della Sala

Publications and source records attributed to S Della Sala.

At least 19 recordsLinked to original sources
PubMed2005

Neuropsychological evidence for separating components of visuo-spatial working memory.

There is increasing evidence to support the idea that visuo-spatial working memory can be segregated into separate cognitive subsystems. However, the nature of these systems remains unclear. In this paper we report data from two brain injured patients suggesting that information about visual appearance is retained in a different subsystem from information about spatial location, and that this differential processing can be observed when the style of presentation (sequential or simultaneous) is controlled.

Adolescent↗
PubMed2004

Walking difficulties in patients with Alzheimer's disease might originate from gait apraxia.

OBJECTIVES: To investigate whether gait apraxia is a possible cause for some of the walking abnormalities shown by patients with Alzheimer's disease. METHODS: 60 patients with Alzheimer's disease, selected as being free from overt extrapyramidal impairment or other potential causes of walking deficits, were assessed with a new test evaluating aspects of walking and related movements. Norms for this test were collected from a sample of 182 healthy volunteers. RESULTS: 40% of the Alzheimer group performed below the cut off score on this test, and half performed poorly. Performance of the Alzheimer group in the walking skills test correlated highly with scores in a test assessing limb apraxia and with dementia severity. CONCLUSIONS: Gait apraxia may be the cause of walking disorders found in a subgroup of patients with Alzheimer's disease. Its detection is made easier by the use of a standardised test, but still relies heavily on the exclusion of other causes of walking deficits. It is a recognisable and independent form of apraxia.

Adult↗
PubMed2004

Dual task effects of walking when talking in Alzheimer's disease.

Previous studies with Alzheimer Disease (AD) patients have suggested that speed and accuracy in walking can be dramatically affected by a simultaneous secondary cognitive task, such as holding a conversation. Two experiments examined the impact on AD patients and age matched elderly controls of cognitive demands while walking. In Experiment 1 walking for AD patients was more affected than it was for the normal elderly by a concurrent cognitive demand. Experiment 2 demonstrated that both groups were equally impaired under dual task conditions when the demands of the cognitive tasks were adjusted for individual levels of ability. We conclude that walking may draw on general executive resources, that walking relies more heavily on these executive resources in the elderly, and on a damaged executive system for AD patients.

Aged↗
PubMed2003

How many camels are there in Italy? Cognitive estimates standardised on the Italian population.

OBJECTIVE: We provided the standardisation of a new Cognitive Estimation Task (CET). PARTICIPANTS: the test was administered to 175 healthy subjects. RESULTS: performance on the Cognitive Estimation Task (CET) is associated with gender (where women show poorer performance than men) and education (where more highly educated individuals show better performance compared to individuals with lower levels of education). However,CET performance is not associated with age. DISCUSSION: the lack of age effects on the CET may be explained by the task dependence on "crystallised intelligence", which is less affected by healthy adult ageing than "fluid intelligence".

Adolescent↗
PubMed2003

Pantomimes are special gestures which rely on working memory.

The case of a patient is reported who presented consistently with overt deficits in producing pantomimes in the absence of any other deficits in producing meaningful gestures. This pattern of spared and impaired abilities is difficult to reconcile with the current layout of cognitive models for praxis. This patient also showed clear impairment in a dual-task paradigm, a test taxing the co-ordination aspect of working memory, though performed normally in a series of other neuropsychological measures assessing language, visuo-spatial functions, reasoning function, and executive function. A specific working memory impairment associated with a deficit of pantomiming in the absence of any other disorders in the production of meaningful gestures suggested a way to modify the model to account for the data. Pantomimes are a particular category of gestures, meaningful, yet novel. We posit that by their very nature they call for the intervention of a mechanism to integrate and synthesise perceptual inputs together with information made available from the action semantics (knowledge about objects and functions) and the output lexicon (stored procedural programmes). This processing stage conceived as a temporary workspace where gesture information is actively manipulated, would generate new motor programmes to carry out pantomimes. The model of gesture production is refined to include this workspace.

Aged↗
PubMed2002

Gait apraxia after bilateral supplementary motor area lesion.

OBJECTIVES: The study aimed at addressing the issue of the precise nature of gait apraxia and the cerebral dysfunction responsible for it. METHODS: The case of a patient, affected by a bilateral infarction limited to a portion of the anterior cerebral artery territory is reported. The patient's ability to walk was formally assessed by means of a new standardised test. RESULTS: Due to an anomaly within the anterior cerebral artery system, the patient's lesion was centred on the supplementary motor regions of both hemispheres. He presented with clear signs of gait apraxia that could not be accounted for by paresis or other neurological deficits. No signs of any other form of apraxia were detected. CONCLUSIONS: The clinical profile of the patient and the analysis of 49 cases from previous literature suggest that gait apraxia should be considered a clinical entity in its own right and lesions to the supplementary motor areas are responsible for it.

Apraxias↗
PubMed2002

Object recognition and object orientation in Alzheimer's disease.

There are a wide variety of neuropsychological deficits in Alzheimer's disease (AD), among which are disorders of visual perception and spatial cognition. The present study investigated the ability of 20 mildly to moderately deteriorated patients with AD (and 174 age- and education-matched controls) on tasks that required them to visually identify, provide the canonical orientation of, and mentally rotate common objects. Some 85% of the AD patients performed poorly on all tasks. The authors were able to identify a small number of individual patients whose pattern of performance represented double dissociations between recognizing objects and knowing their canonical orientation. These findings are interpreted in the context of previous findings, especially as to whether information relating to an object's orientation and identity is independently coded.

Adult↗
PubMed2001

Memory-driven movements in limb apraxia: is there evidence for impaired communication between the dorsal and the ventral streams?

Memory-driven reaching and grasping movements were analysed in patients with left cerebral hemispheric damage and impaired gesture imitation. The dorsal and ventral streams of the visual pathway model of Milner and Goodale (Milner and Goodale, The Visual Brain in Action, 1995) are thought to operate relatively independently. However, cross-connections between the areas of each pathway are likely to enable interactions essential for higher-level praxis. Apraxic errors such as seen in gesture imitation can possibly be understood as arising from a disconnection of the two visual pathways. If the integrated action of the perceptual and visuomotor systems in patients with apraxia is compromised, then we would expect to find indications of impaired motor programming and misreaching in these patients when making movements driven by stored representations. Such a pattern, however, was not found in our sample of apraxic patients. Patients with limb apraxia produced normal movement kinematics and normal end-point accuracy when making memory-driven reaching movements with or without visual guidance of movement. Furthermore, perceptual information about object size and object distance were incorporated as normal in memory-driven grasping movements of these patients.

Aged↗
PubMed2000

Cognition in action: testing a model of limb apraxia.

Assessment of limb apraxia is still suffering from Liepmann's legacy and performance in gesture-processing tests is generally rendered by classifying patients' profile according to the classic clinical labels of ideomotor and ideational apraxia. At odds with other cognitive functions, interpretation of apraxia has suffered from a lack of a reliable model which does justice to its complexity. Recently such a model has been proposed (Rothi et al., 1991, 1997). In this article a modified version of this model is presented and predictions are made according to its functional architecture. Five different patterns of impairment of gesture processing are postulated. To validate the predicted performance profiles, 19 left-hemisphere-damaged patients were assessed by means of an ad hoc battery of four praxis tests. Four of the five predicted apraxia patterns were observed, the fifth being more equivocal. These results support the need to overcome the simplistic dichotomous view of apraxia and confirm the fruitfulness of a model of normal gesture processing in order to understand dissociations in apraxia.

Aged↗
PubMed2000

Perceiving left and imagining right: dissociation in neglect.

Signor Piazza, a patient with a left parieto-occipital haemorrhage and a right thalamic stroke, showed severe right personal neglect (e.g. touching own body parts) and right perceptual neglect in tasks with (e.g. cancelling tasks) or without (e.g. description of a complex picture) motor response. He had also right-sided neglect dyslexia (including single words), without language impairments. However, the patient also presented with a clear left-sided deficit in the representational domain (e.g. imagery tasks). Signor Piazza's pattern of performance suggests dissociation between imagery and perception within the neglect syndrome.

Aged↗
PubMed2000

Nurturing syndrome: a form of pathological bereavement with delusions in Alzheimer's disease.

We report the history and neuroimaging profile of two patients, CS and KC who developed an unusual bereavement reaction with delusions following the deaths of their husbands. Their neuropsychological profiles met criteria for dementia of Alzheimer type. The delusions about their husbands' existence were persistent despite a considerable passage of time after their deaths. SPECT investigation showed reduction of blood flow in the frontal area in both patients when compared with demented controls and in particular a significant reduction in perfusion was observed in the right frontal regions. We argue that this significant reduction of blood flow in the right frontal area, in the context of severe cognitive deterioration, might be responsible for their delusional reaction to bereavement which we interpret as result of reality monitoring and episodic memory failure.

Aged↗
PubMed2000

Intrusion errors in numerical transcoding by Alzheimer patients.

The errors made by brain-damaged patients when they attempt numerical transcoding tasks have recently been considered as a possible aid to early diagnosis of the disease. The transcoding errors of 20 Alzheimer's disease patients are described, and the incidence of each kind of error compared with norms from healthy subjects. Tegnér and Nybäck (Tegnér R, Nybäck H. "To hundred and twenty4our": a study of transcoding in dementia. Acta Neurologica Scandinavia 1990; 81: 177-178) reported that Alzheimer patients often express numerical information in a mixture of verbal and digital codes and Kessler and Kalbe (Kessler J, Kalbe E. Written numerical transcoding in patients with Alzheimer's disease. Cortex 1996; 32: 755-761) suggested that such intrusions of the source code into the target code may not only be largely absent from the responses of the healthy population, but also from the transcoding operations of patients with other kinds of brain damage, such as aphasia. It was found that intrusion errors occurred much more frequently in the transcoding protocols of some of the Alzheimer patients than they do in those of healthy subjects. On the other hand, they were entirely absent from the protocols of other Alzheimer patients. The implications of the findings for the early diagnosis of Alzheimer's disease are discussed, and the phenomenon of intrusion errors is considered in terms of some of the models of arithmetical processing that have been proposed.

Aged↗
PubMed2000

Color-to-figure matching in Alzheimer's disease.

Thirty-three patients with probable Alzheimer's disease were examined on a standardized Color-to-Figure Matching Test (CFMT) for which patients select appropriate colors from a set of colored pencils to match outline pictures of common objects. Seven patients performing below the CFMT cut-off score were further assessed using other tests investigating the naming of these outline pictures of common objects as well as the naming and sorting of colors: One patient performed badly in all tests; three other patients could not be considered true cases of poor object-color retrieval because of their inability to name the objects; and in the remaining three patients with unimpaired object naming (although two of them had word-finding difficulties), their impaired object-color retrieval was found to dissociate from both color sorting and color naming. These findings support the notion of a separation of pure color processing from object-color knowledge. Thus for patients with Alzheimer's disease, there is evidence in a few instances for a dissociation between object-color retrieval and both color sorting and color naming.

Journal Article↗
PubMed2000

Prospective and retrospective memory in normal ageing and dementia: a questionnaire study.

Frequency of prospective memory and retrospective memory failures was rated on a 16-item questionnaire by 862 volunteers, from five groups: patients with Alzheimer Disease (rated by carers), carers of Alzheimer Disease patients, elderly, young, and a group of married couples. Reported memory failures were highest for Alzheimer Disease patients, and lowest for carers, with elderly and young controls in between. More prospective memory than retrospective memory failures were reported in all groups, although the difference was small for Alzheimer Disease patients who were rated near ceiling for both. Prospective memory failures of Alzheimer Disease patients were reported as more frustrating for carers than retrospective memory failures; prospective memory and retrospective memory failures frustrated Alzheimer Disease patients equally. Data from the couples indicated that there were no biases resulting from rating on behalf of someone else. These results suggest that: (1) normal ageing has no greater effect on self-reported retrospective memory than prospective memory failures, (2) the relatively small number of memory failures reported by carers may result from comparing themselves with the Alzheimer Disease patients in their care, and (3) prospective memory failures have a greater impact on the lives of the carers and are therefore more likely to be reported as early indicants of the disease.

Adolescent↗