Biomedical subjects

Laura Piccardi

Publications and source records attributed to Laura Piccardi.

6 recordsLinked to original sources

PubMed2006

Neural bases of personal and extrapersonal neglect in humans.

Human awareness of left space may be disrupted by cerebral lesions to the right hemisphere (hemispatial neglect). Current knowledge on the anatomical bases of this complex syndrome is based on the results of group studies that investigated primarily the best known aspect of the syndrome, which is visual neglect for near extrapersonal (or peripersonal) space. However, another component-neglect for personal space-is more often associated with, than double-dissociated from, extrapersonal neglect, especially, in chronic patients. The present investigation aimed at exploring the anatomical substrate of both extrapersonal and personal neglect by using different advanced methodological approaches to lesion-function correlation. Fifty-two right ischaemic patients were submitted to neuropsychological assessment and in-depth MRI evaluation. The borders of each patient's lesion were delimited onto its own high-resolution anatomical image and then submitted to an automated spatial normalization algorithm. Besides conventional lesion density plots and subtraction analysis, region-based statistical analyses were performed on percentage values of the lesioned tissue also using a new parcellation of the white matter (WM). Data were finally submitted to voxelwise statistical analysis using a recently proposed method (voxel-based lesion-symptom mapping). Results converged in showing that awareness of extrapersonal space is based on the integrity of a circuit of right frontal (ventral premotor cortex and middle frontal gyrus) and superior temporal regions, whereas awareness of personal space is rooted in right inferior parietal regions (supramarginal gyrus, post-central gyrus and especially the WM medial to them). Common but less crucial regions for both neglect sub-types were located in the temporo-peri-Sylvian cortex. We suggest that extrapersonal space awareness critically involves a ventral circuit recently described for the exogenous allocation and reorienting of attention in space. Disruption of personal space awareness, instead, seems to be due to a functional disconnection between regions important for coding proprioceptive and somatosensory inputs, and regions coding more abstract egocentric representations of the body in space. In conclusion, present data strongly support a segregation of personal and extrapersonal spatial awareness in humans, both from a functional and an anatomical point of view.

Adult↗

PubMed2006

Efficacy of visuo-spatial training in right-brain damaged patients with spatial hemineglect and attention disorders.

Several rehabilitative approaches have been used to reduce neglect disorders. Some studies tried to demonstrate that hemineglect can be ameliorated by using tasks promoting attentional activation towards the neglected hemispace (Robertson et al., 1995, 2001). As a consequence, a functional link between level of attention and disorders of space exploration has been proposed. For this reason we tried to explore the possible role of attentional deficits on the efficacy of a standard neglect treatment based on visuo spatial rehabilitation. In this study we then examined the performances of a selected group of seven right brain damaged patients, suffering from both severe hemineglect and attentional deficits (of both phasic and tonic components of attention), to several tasks before and after a visuo-spatial training (VST) whose efficacy has been already demonstrated (Pizzamiglio et al., 1992). Results showed that VST induces a significant remission of hemineglect symptoms independently from disorders of attention. Moreover, after visuo-spatial rehabilitation, no improvement of attentional deficits is detectable.

Aged↗

PubMed2005

Representational neglect and navigation in real space.

Topographical orientation relies on several cognitive strategies adopted by humans to move within the environment. In the present study, we investigate whether mental representation disorders affect specific cognitive mechanisms subserving human orientation. In order to differentiate distinct cognitive mechanisms involved in topographical orientation, we created a human version of the well-known "Morris Water Maze" and tested left and right brain damaged patients in a place-learning task. The test required the subjects to explore an experimental room in which no visual cues were present, find a target location, and then reach it in different conditions. The ability to memorize target locations in short- and long-term memory was also assessed. We found that all participants were able to reach the target location by using idiothetic cues (vestibular inputs, motor efferent copy, etc.). On the other hand, when starting position changed and re-orientation was necessary to reach the target location, in order to compute a new trajectory, only patients affected by representational neglect got lost. These results provide the first neuropsychological evidence of involvement of mental representation in a specific cognitive process allowing humans to reach a target place from any location in the environment.

Adult↗

PubMed2005

Lack of orientation due to a congenital brain malformation: a case study.

Topographical disorientation is usually described in patients who have lost the ability to orient themselves as a consequence of acquired focal brain damage. Here, we describe the case of a 20-year-old woman with a congenital brain malformation who has never been able to orient herself within the environment. We addressed in detail her ability to orient and navigate within the environment by administering a number of tasks in both ecological and experimental surroundings. The results indicate a complete inability to use any kind of strategy useful for orientation.

Adolescent↗

PubMed2004

Language disorder in a child with early left thalamic lesion.

In this paper we present the case of a child with early left thalamic vascular damage who subsequently developed a language disorder. At 3 years and 8 months, her language was poor and unintelligible and showed phonetic, phonological and morpho-syntactic disorders. She did not exhibit any signs of mental retardation. After specific speech therapy, she improved in all linguistic skills. Given the lack of reports on thalamic lesions in children, this paper describes the effect of a thalamic injury in the earliest phases of language acquisition in a child who showed consistent phonological disorders. This case seems to confirm early hemispheric specialisation and the importance of a timely therapy.

Cognition↗

PubMed2003

Dissociation between personal and extrapersonal neglect in a crossed aphasia study.

Abstract Several reports document crossed aphasia following a right cerebral infarct. However, few of them provide a detailed investigation of associated neuropsychological disorders. A personal neglect disorder with no difficulty in orienting attention in the contralesional space has not been frequently reported independently of lesion side for the language deficit. In most cases, the deficit is described in the acute period. We report the case of a patient who showed severe crossed aphasia several months after cerebral damage. In addition to his language deficit, he suffered from finger agnosia, acalculia, and right/left confusion. Although he was able to orient attention in the contralesional space, he had a persistent personal neglect disorder with severe difficulty in attending to his own body. Results suggest that right hemisphere language dominance does not preclude ipsilateral specialisation for other functions. Furthermore, the dissociation between the two spatial functions provides further confirmation that they are subserved by two independent systems.

Agnosia↗