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Biomedical subjects

Raffaella I Rumiati

Publications and source records attributed to Raffaella I Rumiati.

11 recordsLinked to original sources
PubMed2006

Learning hierarchically structured action sequences is unaffected by prefrontal-cortex lesion.

This study tested the impact of prefrontal-cortex lesion on learning hierarchically structured action sequences. Using a visual-manual serial reaction time task, we had subjects first perform five blocks of trials with a hierarchically structured 14-element action sequence and then tested for sequence-specific learning by introducing a pseudo-random transfer sequence. Relative to control subjects (N = 39), we found that both lateral frontal (N = 16) and medial frontal (N = 18) patients showed reduced overall performance benefits across the training phase. In contrast, the negative transfer test showed significantly increased reaction times in all patient groups, indicating robust sequence-specific learning. This learning was not significantly different from that of the control group. Taken together, the data suggest that learning hierarchically structured action sequences is unimpaired in patients with prefrontal-cortex lesion.

Adult↗
PubMed2005

Task-set inertia and memory-consolidation bottleneck in dual tasks.

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations ("ignore" trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC --> BC vs. BC --> BC) in Experiment 3.

Attention↗
PubMed2005

Common and differential neural mechanisms supporting imitation of meaningful and meaningless actions.

Neuropsychological studies indicate that, after brain damage, the ability to imitate meaningful or meaningless actions can be selectively impaired. However, the neural bases supporting the imitation of these two types of action are still poorly understood. Using PET, we investigated in 10 healthy individuals the neural mechanisms of imitating novel, meaningless actions and familiar, meaningful actions. Data were analyzed using SPM99. During imitation, a significant positive correlation (p < .05, corrected) of regional cerebral blood flow with the amount of meaningful actions was observed in the left inferior temporal gyrus only. In contrast, a significant positive correlation (p < .05, corrected) with the amount of meaningless movements was observed in the right parieto-occipital junction. The direct categorical comparison of imitating meaningful (100%) relative to meaningless (100%) actions showed differential increases in neural activity (p < .001, uncorrected) in the left inferior temporal gyrus, the left parahippocampal gyrus, and the left angular gyrus. The reverse categorical comparison of imitating meaningless (100%) relative to meaningful (100%) actions revealed differential increases in neural activity (p < .001, uncorrected) in the superior parietal cortex bilaterally, in the right parieto-occipital junction, in the right occipital-temporal junction (MT, V5), and in the left superior temporal gyrus. Increased neural activity common to imitation of meaningless and meaningful actions compared to action observation was observed in a network of areas known to be involved in imitation of actions including the primary sensorimotor cortex, the supplementary motor area, and the ventral premotor cortex. These results are compatible with the two-route model of action imitation which suggests that there are at least two mechanisms involved in imitation of actions: a direct mechanism transforming a novel action into a motor output, and a semantic mechanism, on the basis of stored memories, that allows reproductions of known actions. Our results indicate that, in addition to shared neural processes, the direct and the semantic mechanisms that underlie action imitation also draw upon differential neural mechanisms. The direct mechanism underlying imitation of meaningless actions differentially involves visuospatial transformation processes as evidenced by activation of areas belonging to the dorsal stream. In contrast, imitation of meaningful actions differentially involves semantic processing as evidenced by activation of areas belonging to the ventral stream.

Adult↗
PubMed2004

Neural basis of pantomiming the use of visually presented objects.

UNLABELLED: Neuropsychological studies of patients suffering from apraxia strongly imply a left hemisphere basis for skillful object use, the neural mechanisms of which, however, remain to be elucidated. We therefore carried out a PET study in 14 healthy human volunteers with the aim to isolate the neural mechanisms underlying the sensorimotor transformation of object-triggers into skilled actions. We employed a factorial design with two factors ( RESPONSE: naming, pantomiming; and TRIGGER: actions, objects) and four conditions (IA: imitating the observed pantomime; IO: pantomiming the use of the object shown; NA: naming the observed pantomime; NO: naming the object shown). The design thus mainly aims at investigating the interaction [i.e. (IO-IA)-(NO-NA)] which allows the assessment of increased neural activity specific to the sensorimotor transformation of object-triggers into skilled actions. The results (P < 0.05, corrected) showed that producing a wide range of skilled actions triggered by objects (controlled for perceptual, motor, semantic, and lexical effects) activated left inferior parietal cortex. The data provide an explanation for why patients with lesions including left parietal cortex suffer from ideational apraxia as assessed by impaired object use and pantomining to visually presented objects.

Adult↗
PubMed2004

Praxic skills in down and mentally retarded adults: evidence for multiple action routes.

Functional relationships between praxic performance and visual recognition ability of mentally retarded adults are discussed, in an attempt to integrate findings from developmental disorders of action with those described in the adult literature. Three groups of participants took part in the study: adults with Down's syndrome (D), Mentally Retarded adults (MR), and mental age-matched controls (C). Three experiments were conducted. A gesture production task (Experiment 1) aimed to test ability to demonstrate the object use under three different experimental conditions: first, participants could only see the objects; second, they were allowed to see as well as to touch the objects; and third, participants were presented with the object names. An object decision task (Experiment 2) assessed the participants' ability to access structural descriptions of objects from vision. An imitation task (Experiment 3) was administered in order to test for the presence of Ideomotor Apraxia. Our results suggest that the two pathological samples may use different processing routes to action.

Adult↗
PubMed2004

Effects of strategies on mental rotation and hemispheric lateralization: neuropsychological evidence.

We can predict how an object would look if we were to see it from different viewpoints by imagining its rotation. This essential human ability, called mental rotation (MR), guides individuals' actions by constantly updating their environmental consequences. It is, however, still under debate whether the way in which our brain accomplishes this operation is determined by the type of stimulus or rather by a mental strategy. Here we present neuropsychological evidence sustaining the view that what matters is the type of strategy adopted in MR. Thus, independently of the type of stimulus, patients with left hemisphere lesions showed a selective deficit in MR as a consequence of their manual activity, whereas patients with right hemisphere lesions were found impaired in MR by means of a visual strategy. We conclude that MR is achieved by recruiting different strategies, implicitly triggered or prompted at will, each sustained by a unilateral brain network.

Adult↗
PubMed2003

Dissociation between the mental rotation of visual images and motor images in unilateral brain-damaged patients.

Deficits in the mental rotation of body parts and of external objects can be doubly dissociated (Rumiati, Tomasino, Vorano, Umiltà, & De Luce, 2001; Sirigu & Duhamel, 2001; Tomasino, Rumiati, & Umità, in press). The aim of this study was to replicate this finding and to then investigate the relevance of the specific hemispheres in these deficits. Nine patients with unilateral lesions (five in the Left Hemisphere and four in the Right) and 20 control subjects, performed a single task requiring mental rotation of hands, and two tasks requiring mental rotation of external objects. RH patients were impaired in the rotation of external objects, but showed intact performance on the rotation of hands; the opposite pattern was found for LH patients. These results support the view that the LH contributes to the mental rotation of hands, recruiting processes specific to motor preparation, while the RH is specialized for mental rotation of external objects.

Adult↗
PubMed2002

Imitation without awareness.

Imitation is a characteristic but little-understood function of the human brain and of some higher animals. The direct matching hypothesis suggests that a specialised brain circuit is able to extract and directly copy the motor commands of another person's observed actions. Here we investigate how conscious people are of this kind of imitation. We first showed that imitation reactions are faster than simple visual reaction times, consistent with a direct matching circuit in the CNS. We next compared the perceived time of imitation reactions in 17 healthy subjects with other kinds of actions. We found a significant delay in subjects' awareness of their own imitation reactions. Thus, while imitation reactions are unusually fast, subjects are not aware of this. The brain's direct-matching circuit for imitation partly bypasses conscious awareness.

Adult↗
PubMed2002

Action sequencing deficit following frontal lobe lesion.

Frontal lobe patients carried out temporal sequencing tasks related to actions that differed in terms of their abstractness using both verbal and pictorial presentations. A generalized impairment was found: neither a type of action effect nor a modality of item presentation effect was present. The patients also carried out a corresponding action production task and produced actions quickly and without errors. The frontal lobe patients were also spared in generating verbal descriptions of actions: they were as accurate as normal controls both in terms of the details reported and in maintaining the temporal sequence. It has been argued that the difficulty in processing the temporal dimensions of actions following frontal lobe lesions is due to some form of disruption of the action representation. However, no action representational deficits were present in our frontal lobe patients. Thus, they cannot account for our findings. On the contrary, we suggest that the action sequencing deficit was a consequence of the difficulties patients experienced in rejecting wrong alternatives presented by the stimulus situation.

Activities of Daily Living↗
PubMed2002

Executive function profile of children with attention deficit hyperactivity disorder.

We explored the neuropsychological profile for executive functions of children with attention deficit hyperactivity disorder (ADHD) to assess whether problems associated with the two most cited relevant processes--inhibition and attentional problems--were the core of any executive function difficulty. A battery of executive function tests was administered to 31 children with a clinical diagnosis of ADHD and to 33 normal control participants, all aged between 7 and 12. The executive function battery encompassed a number of tasks, selected because each had multiple measures: a sustained attention reaction time task, a related vigilance task, an adaptation of the Hayling Sentence Completion Test, an adaptation of the Brixton Spatial Rule Attainment Test, a Letter Fluency task, a number Stroop task, and an "n-back" working memory task. The overall pattern of the results fit well with those obtained in previous studies as far as abnormalities of the ADHD group in the domain of inhibitory processes, attentional functions, and executive functions. The children with ADHD, although performing well on baseline tasks, performed more poorly than the controls on all the experimental tasks with one borderline exception: Letter Fluency, where the children with ADHD showed a very different pattern than most adult frontal lobe subgroups. However, there was no specific impairment on measures of inhibitory processes. In addition, strategy generation and use were severely affected in the ADHD group. Particular findings fitted well with disorders of a high-level effort system and of a monitoring system.

Analysis of Variance↗