Biomedical subjects

Nicoletta Beschin

Publications and source records attributed to Nicoletta Beschin.

7 recordsLinked to original sources

PubMed2006

Representing target motion: the role of the right hemisphere in the forward displacement bias.

Patients with left spatial neglect, patients with right hemisphere damage but no neglect, and a control group were asked to judge the final position of a series of moving targets. Both patient groups showed attentional deficits. All 3 groups demonstrated a forward displacement bias, overestimating the final target position along the object trajectory. However, in both patient groups the size of this forward displacement bias decreased as the distance the target traveled before vanishing increased. For horizontally moving targets, at the maximum distance only the control group showed significant forward displacement. For all 3 groups, the direction in which the target traveled had no influence, but the size of the forward displacement increased as target speed increased. Several attentional explanations of these results are considered, including the differential allocation of spatial attention between central and peripheral locations, differences between exogenous and endogenous attention, and deficits in sustained attention.

Aged↗

PubMed2005

The processing of the right-sided accent mark in left neglect dyslexia.

Italian polysyllabic words with stress falling on the last syllable are written with a diacritic sign on the last vowel. It allows discrimination between two words with the same orthographic segments (e.g., papa [pope], papà [dad]). The effect of the accent mark in left neglect dyslexia has never been investigated. In the current study, six patients with neglect dyslexia were asked to read aloud homographic words and non-words, with or without the accent mark. The presence of the accent improved reading performance of three patients but only with real words. In contrast, two patients ignored the accent mark, even if it relied on the right ipsilesional space. We conclude that the accent mark is computed separately from letter identity and that it can act as an important cue for lexical access.

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PubMed2004

Verbal recall in amnesiacs under conditions of diminished retroactive interference.

In amnesiacs, stimuli that at first can be recalled are usually forgotten within 1 min, but the conditions required for this severe forgetting have remained unknown. To examine this, six patients with amnesia due to head injury or stroke and six normal controls heard lists of words (Experiment 1) and stories (Experiment 2). These stimuli were to be recalled immediately or after an extended test delay (10 min in Experiment 1; 1 h in Experiment 2). Although severe forgetting occurred in the amnesiacs following activity-filled delays, much less forgetting occurred in four of these patients after delays spent in a dark, quiet room. This was true even when the patients appeared to sleep during the delays. The results show, in a novel manner, that one deficit underlying their amnesias is vulnerability to retroactive interference.

Adult↗

PubMed2004

Preserved visuo-spatial transformations in representational neglect.

Patients with representational unilateral neglect were impaired in immediate recall of novel material on the neglected side as presented (viewed and removed or verbally described) or following mental rotation. Transforming material from the neglected (left) side to the non-neglected (right) side resulted in no additional loss; patients were unimpaired in directing attention to the neglected side of their representation in order to perform the mental rotation. These findings cannot be explained by the widely adopted attention deficit hypothesis for representational neglect. It is suggested that the disorder arises from damage to temporary storage functions of visuo-spatial working memory.

Adult↗

PubMed2002

Chronic anosognosia: a case report and theoretical account.

Unawareness of motor disorders (anosognosia) has often been reported after brain lesions, and it has been considered a temporary condition common in the acute and post-acute phases. The presence of anosognosia in a chronic phase (i.e. lasting more than few weeks) is a rare occurrence, thought to be the result of reasoning deficits which prevent patients from performing an adequate check of reality. Although this assumption is widely shared amongst researchers, only a few studies have actually addressed this issue. We report on the case of a patient (NS) who was still showing anosognosia for hemiplegia 1 year after a traumatic brain-head injury, while his reasoning abilities were well preserved. By means of a series of tests and experiments, we evaluated the main theoretical approaches. NS's long-lasting anosognosia is discussed in terms of a combination of clinical manifestations, whereby personal neglect and motor-sensory information play a key role in preventing awareness, whereas memory difficulties in updating pre-existing personal schema may be crucial in maintaining NS's anosognosic status.

Adult↗

PubMed2002

Agnosia for object orientation: naming and mental rotation evidence.

We have previously reported the performance of a patient (NL) who could recognize objects, but appeared to lack knowledge of their orientation. These results were interpreted as evidence that NL had isolated access to a viewpoint-independent (ventral stream) object recognition system. However, because NL's responses on naming tasks were not timed, it was not possible to establish whether he showed the same pattern of reaction time performance generally accepted as evidence of a 'mental rotation' strategy in neurologically normal subjects. Here we report NL's performance on two reaction time tasks, testing his ability to transform images when naming, and discriminating between rotated mirror image objects. As predicted, and in contrast to normal volunteers, NL showed no 'mental rotation' effect in his naming of misoriented objects. Paradoxically, he performed well on a traditional Shepard and Metzler mental rotation task. He also showed a normal orientation effect when dealing with misoriented faces. These findings offer further support for viewpoint-independent theories of object recognition, and bolster the claim that object orientation knowledge can be regarded as, in some respects, a special class of spatial information.

Aged↗

PubMedDate not supplied

Just lying there, remembering: improving recall of prose in amnesic patients with mild cognitive impairment by minimising interference.

The hallmark of amnesia is poor explicit long-term memory along with normal short-term memory. It is often stated that information encountered by amnesic patients is forgotten within 1 minute of presentation. However, previous work has not distinguished between forgetting as a function of time versus the interfering material occupying that time. We show that there is a marked benefit of reduced interference in amnesic patients with mild cognitive impairment (MCI), a condition that is characterised by anterograde amnesia in the absence of other neuropsychological deficits and carries an increased risk for Alzheimer's disease. The result suggests that long-term memory is encoded in these patients to a greater extent than had been realised but that their memory is highly vulnerable to interference.

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