Biomedical subjects

G Cocchini

Publications and source records attributed to G Cocchini.

5 recordsLinked to original sources

PubMed1999

Working memory and vigilance: evidence from normal aging and Alzheimer's disease.

Both single unit recording and neuroradiological studies suggest that frontal and executive processes are necessary for visual maintenance rehearsal. This observation is linked to the classic vigilance literature by the proposal that vigilance decrement is found when the subject is required to maintain a representation over a brief delay. Vigilance performance was therefore studied in a sample of elderly subjects who were tested over a 40-min period involving perceptual or memory-based tasks which were matched for initial level of performance. There was a significant interaction between task and delay, with only the memory-based task showing decrement. A second study used the same two tasks to investigate vigilance performance in patients suffering from probable Alzheimer's Disease. Over a 15-min delay period, an equivalent interaction effect occurred, again indicating substantially greater decrement for the memory-based task. The results are interpreted as consistent with a role for the executive processes of working memory in both visual rehearsal and vigilance performance.

Aged↗

PubMed1999

Neglect without extinction.

A patient, AB, is reported who showed clear signs of neglect but no extinction (N+ E-). Several hypotheses proposed to account for this dissociation were put to the test. The postulated association between motor neglect and extinction did not hold good, nor did the possibility that the N+ E- dissociation may be traced back to the difference in test requirements and therefore observed only in patients with object-centred neglect. Likewise, manipulating the physical features of the stimuli (relative size, exposure time, presentation synchrony) did not elicit extinction. However, when the task demands were modified by asking the patient to perform a further spatial analysis of the stimuli, rather than simply detect them, extinction emerged. Since AB performed well on several neglect tasks requiring parallel processing, while failing all tasks calling for serial processing, the hypothesis is put forward that AB's N+ E- dissociation could be interpreted within the parallel/serial distinction framework.

Aged↗

PubMed1997

What the eyes perceive, the brain ignores: a case of pure unilateral representational neglect.

Bisiach and Luzzatti (1978) provided evidence that unilateral spatial neglect is not only a disorder of visual perception, but also can affect mental representations such that patients fail to report the left side of scenes or objects in mental imagery. However in case reports of representational neglect generally it is accompanied by perceptual neglect. We report a rare occurrence of a patient (NL) who presents a persistent unilateral neglect which appears to be limited to visual imagery. The deficit appeared in tasks which require the formation and manipulation of new visuo-spatial representations as well as those which require access to information about familiar scenes. The patient, who had a lesion in the right parietal lobe, showed no evidence of perceptual or personal neglect, although there was some evidence of visual extinction. We argue that the concept of visuo-spatial working memory can provide a framework within which to interpret aspects of the representational form of neglect, whether or not it is accompanied by perceptual neglect.

Aged↗

PubMed1996

A case of simulated, psychogenic or focal pure retrograde amnesia: did an entire life become unconscious?

A case of pure retrograde amnesia following mild head injury is reported. Neuropsychological, psychodynamic and statistical approaches are employed in an attempt to disentangle the clinical picture presented by the patient. Focal retrograde amnesia, psychogenic retrograde amnesia and simulated amnesia are all taken into account. From a public events questionnaire and an inquiry about famous people, consistency analyses showed that the patient was able implicitly to use information she denied having, but at the same time, made us lower the probability of a simulated amnesia. Moreover, psychodynamic analysis showed that the patient's personality structure was compatible with hysterical patterns and we suggest that the patient's memory defect may be related to her personality. It seems less likely, though still possible, that the case may be explained in terms of deliberate simulation. In this case we conclude that the classification along the conscious/unconscious dimension seems more informative than the contrast between psychogenic and organic genesis.

Adult↗

PubMed1994

Alzheimer patients show a sensitivity decrement over time on a tonic alertness task.

Tonic alertness was investigated in Alzheimer patients and normal elderly subjects. Sensitivity and criterion shifts were investigated across 45 min of continuous testing using a high event rate test with very low target probability. Alzheimer patients showed a significant sensitivity decrement over time that was unrelated to dementia severity. These results suggest that tonic alertness is impaired by Alzheimer's disease even in its early stages.

Aged↗