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Biomedical subjects

Roberto Cubelli

Publications and source records attributed to Roberto Cubelli.

9 recordsLinked to original sources
PubMed2006

List effect in apraxia assessment.

Imitation tests encompassing intermingled meaningful and meaningless items are normally used to assess ideomotor apraxia, implicitly assuming that they would test the lexical and the non-lexical route, respectively. However, these mixed lists might induce a "list composition" effect similar to that found in word recognition studies where familiar material can be processed via the non-lexical route. This hypothesis was put to test by examining praxis skills of 23 left-hemisphere damaged patients using the same gestures in two formats: pure and mixed lists (i.e., meaningless or meaningful gestures administered separately or intermingled, respectively). Results showed that patients performed better on the imitation task when pure lists were used. Moreover, asymmetries of performance were observed. Patient SL scored better in the imitation of meaningful gestures in the pure list than in the mixed list condition. Patient CA performed poorly in the imitation of meaningless gestures only in the mixed list condition. Dissociations observed in imitation tasks could be biased by the use of mixed lists. Also "pure" lists should be used for the diagnosis of imitation deficits in apraxia.

Adult↗
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.

Aged↗
PubMed2005

Is judgement of line orientation selectively impaired in right brain damaged patients?

The judgement of line orientation test (JLOT) is widely used to assess visuo-spatial processing. Most neuropsychological studies have shown that on this task right hemisphere damaged (RHD) patients are significantly more impaired than left hemisphere damaged (LHD) patients, suggesting a dominant role of the right hemisphere in discriminating line orientation. To investigate whether other factors can affect performance on JLOT, a modified version of the test, consisting of the 30 original test items and their mirror images, was employed. In Experiment 1 normal participants were more accurate in discriminating the left lines of the original items, and the right lines of the mirror-reversed items, thus indicating that in original JLOT the stimulus arrays comprise lines on the left side that are easier to judge than lines on the right. In Experiment 2, RHD patients with visual neglect were significantly more impaired than patients without neglect, who performed similarly independently from the side of the lesion. Among patients without neglect, however, LHD patients were more accurate than RHD patients without neglect with the original items, but produced more errors than RHD patients without neglect when faced with the mirror-reversed items. Overall, the results of the present study suggest that the greater impairment on standard JLOT shown by RHD patients has to be interpreted as the by-product of the presence of visual neglect, which is more frequent following right hemisphere damage, and of the uneven distribution of the stimulus lines, which are easier to discriminate in the left space. The clinical and theoretical implications of the results are discussed.

Adolescent↗
PubMed2005

Is handedness recognition automatic? A study using a Simon-like paradigm.

The authors used a modified Simon task (J. R. Simon, 1969) to assess the automatic recognition of handedness. Participants responded to the color of a circle in the center of the photograph of a right or a left hand, displayed in the center of the computer screen. A regular Simon effect was found for back views, whereas a reverse Simon effect was found for palm views. This pattern of results was found when the forearm was present (Experiment 2), when 1 finger at a time was rendered invisible (Experiment 3), and when the hands were connected to a body image (Experiment 4). When the hands were cut at the wrist, no effect emerged (Experiment 1). These findings suggest an automatic encoding of the relative position of the hand in relation to the body (imaginary or real) rather than the automatic encoding of handedness.

Automatism↗
PubMed2003

Impairments of trunk movements following left or right hemisphere lesions: dissociation between apraxic errors and postural instability.

Stroke patients present with apraxic or postural deficits involving trunk movements. Praxis and posture control have been associated with the functions of the left and the right hemisphere, respectively. For the first time, in this study the occurrence of apraxic and postural components in trunk movement deficits following right and left hemisphere lesions were investigated in the same participants. Twenty-three patients with left (L/pt), 12 with right (R/pt) hemisphere lesion, and 30 healthy controls were evaluated with a 21-item test assessing the imitation of meaningless, symbolic and reaching movements presented twice on visual or proprioceptive modality. Erroneous, motor responses of the trunk were classified as postural (compensations to overcome stability or asymmetry deficits) or apraxic (execution errors not due to biomechanical constraints). Postural instability reactions were significantly more frequent among the R/pts, whilst apraxic responses were overwhelming within the L/pts. The findings are consistent with the view that the left hemisphere is dominant for praxis and suggest that this dominance be extended to trunk praxis. The results also support the hypothesis that trunk postures are coded in relation to the environment by a representational system. A widespread network, mainly sitting in the right hemisphere, subserves this postural system. The distinction between praxic and postural deficits in executing trunk movements should be kept in mind when evaluating trunk movement difficulties shown by stroke patients, in following up their recovery or when tailoring rehabilitation programmes.

Adult↗
PubMed2003

On recognizing proper names: the orthographic cue hypothesis.

Five experiments investigated the recognition of proper names and common nouns using the lexical decision paradigm. In Experiments 1-3 the case of the initial letter of written stimuli was systematically varied. An advantage was consistently found for proper names written with the first letter in capital. Crucially, response times to proper names with the first letter in lowercase and to common nouns irrespective of the case of the first letter did not differ from each other. No difference between proper names and common nouns emerged in Experiment 4 where the stimuli were presented auditorily, and in Experiment 5 where a visual lexical decision task was performed with illegal non-words. The pattern of results shows that the proper name advantage is orthographic in nature and rules out an account in terms of semantic, morphological or other lexical variables. A model is proposed in which information about the case of the first letter is specified in the abstract multidimensional orthographic representation mediating written word recognition.

Adult↗