Showing papers by "Eraldo Paulesu published in 2005"
TL;DR: Denial was associated with lesions in areas related to the programming of motor acts, particularly Brodmann's premotor areas 6 and 44, motor area 4, and the somatosensory cortex, suggesting that monitoring systems may be implemented within the same cortical network that is responsible for the primary function that has to be monitored.
Abstract: In everyday life, the successful monitoring of behavior requires continuous updating of the effectiveness of motor acts; one crucial step is becoming aware of the movements one is performing. We studied the anatomical distribution of lesions in right-brain-damaged hemiplegic patients, who obstinately denied their motor impairment, claiming that they could move their paralyzed limbs. Denial was associated with lesions in areas related to the programming of motor acts, particularly Brodmann's premotor areas 6 and 44, motor area 4, and the somatosensory cortex. This association suggests that monitoring systems may be implemented within the same cortical network that is responsible for the primary function that has to be monitored.
309 citations
TL;DR: Evidence is provided that altered activation observed within the reading system is associated with altered density of grey and white matter of specific brain regions, such as the left middle and inferior temporal gyri and the left arcuate fasciculus, which supports the view that dyslexia isassociated with both local grey matter dysfunction and with altered connectivity among phonological/reading areas.
Abstract: Voxel-based morphometry was used to assess the consistency among functional imaging and brain morphometry data in developmental dyslexia. Subjects, from three different cultural contexts (UK, France and Italy), were the same as those described in a previous PET activation paper, which revealed a common pattern of reduced activation during reading tasks in the left temporal and occipital lobes. We provide evidence that altered activation observed within the reading system is associated with altered density of grey and white matter of specific brain regions, such as the left middle and inferior temporal gyri and the left arcuate fasciculus. This supports the view that dyslexia is associated with both local grey matter dysfunction and with altered connectivity among phonological/reading areas. The differences were replicable across samples confirming that the neurological disorder underlying dyslexia is the same across the cultures investigated in the study.
248 citations
TL;DR: Left caloric vestibular stimulation is effective on both left and right hemianesthesia because it modulates the hemisphere that has a more complete representation of, or is capable to attend to, the whole somatosensory surface of the body.
Abstract: Background: Left caloric vestibular stimulation (CVS) transiently reduces impairments of right-brain-damaged patients with left unilateral neglect, including left hemianesthesia, contralateral to the side of the lesion (contralesional). Conversely, no effect on right contralesional hemianesthesia in left-brain-damaged patients is seen with right CVS. This discrepancy is unexplained. Methods: The authors explored the effect of CVS on right- and left-brain-damaged patients with hemianesthesia. One left-brain-damaged patient had an fMRI study during tactile stimulation before and after left CVS. The same fMRI touch study, without CVS, was performed in neurologically unimpaired subjects. Results: A transient remission of right hemianesthesia associated with left brain damage was observed, provided that cold CVS was administered to the left ear. In the left-brain-damaged patient studied with fMRI, left CVS modulated the neural response to right hand tactile stimuli of a portion of the secondary somatosensory area (SII) of the right hemisphere. In neurologically unimpaired subjects, fMRI scans showed that the same part of area SII in the right hemisphere was activated by ipsilateral right-sided touches and to a larger extent than area SII in the left hemisphere by left-sided touches. Conclusions: Left caloric vestibular stimulation is effective on both left and right hemianesthesia because it modulates the hemisphere that has a more complete representation of, or is capable to attend to, the whole somatosensory surface of the body. These results suggest a hardwired hemispheric asymmetry in hand representation, starting from a somatotopically organized brain region such as area SII.
78 citations
01 Jan 2005
TL;DR: FMRI can greatly enhance knowledge about the functioning of the mind-brain system, provided that scientists are aware of its constrains and take into account that each experimental decision, from parameter setting to statistical analysis, has specific consequences and thus has to be considered in the result interpretation.
Abstract: Looking at the Mind through the Lens of Functional Magnetic Resonance Imaging: Chances and Challenges Steven Small (small@uchicago.edu) Department of Neurology and Brain Research Imaging Center, University of Chicago 5841 S. Maryland Ave., MC-2030 - Chicago, IL 60637 USA Katiuscia Sacco (sacco@psych.unito.it) Center for Cognitive Science, University of Turin via Po 14 - 10123 Torino, Italy Methodological Issues and Technical What’s Hidden behind a Brain Map? Summary Advances in non-invasive brain scanning and imaging technologies over the last ten years have opened up promising new methods of work for researchers. Neuroimaging techniques has enabled scientists to look for the first time into the human brain in vivo, to literally watch it while it works. This has revealed exciting insights into the spatial and temporal changes underlying a broad range of brain functions, including perceptual and motor abilities (e.g. Di Salle et al., 2003; Hlustik et al., 2001), normal and abnormal language processes (e.g. Paulesu et al., 2001; Perani, et al., 2003; Small & Nusbaum, 2004) and higher cognitive processes (for a discussion of neuroimaging results of higher level cognition see Cappa & Grafman, Functional magnetic resonance imaging (hereafter fMRI), being the least invasive of brain imaging techniques, has gained an increasing popularity among cognitive scientists and in the last decade it appeared that its use was alone a good reason for assuring publication. At present, once the glamour of the novelty has cooled down, it is time to seriously assess its real contribution in the study of cognitive processes: can fMRI really challenge some of the remaining frontiers in neuroscience? To what extent can we trust what we see? In our view, fMRI can greatly enhance our knowledge about the functioning of the mind-brain system, provided that scientists are aware of its constrains and take into account that each experimental decision, from parameter setting to statistical analysis, has specific consequences and thus has to be considered in the result interpretation. The goal of this symposia is to discuss the advantages and limitations of fMRI at the epistemological, methodological and technical levels. Tricks: Francesco Di Salle, University of Pisa (Italy) Cognitive Neuroscience and Functional Imaging: What can be Learned from Patient Studies Eraldo Paulesu, University of Milan (Italy) What Can fMRI Show us and what Cannot Stefano Cappa, University of Milan (Italy) Beyond Localization: Cortical Circuit Analysis of fMRI Data Ana Solodkin, University of Chicago (USA) References Cappa, S. F., Grafman, J. (2004). Neuroimaging of higher cognitive function. Cortex, 40(4-5), 591-592. Di Salle, F., Esposito, F., Scarabino, T., Formisano, E., Marciano, E., Saulino, C., Cirillo, S., Elefante, R., Scheffler, K., Seifritz, E. (2003). fMRI of the auditory system: understanding the neural basis of auditory gestalt. Magnetic Resonance Imaging, 21(10),1213-24. Hlustik, P., Solodkin, A., Gullapalli, R. P., Noll, D. C, Small, S. L. (2001). Somatotopy in human primary motor and somatosensory hand representations revisited. Cerebral Cortex,11(4), 312-21. Paulesu, E., Demonet, J. F., Fazio F., McCrory, E., Chanoine, V., Brunswick, N., Cappa, S. F., Cossu, G., Habib M., Frith C. D. & Frith U. (2001). Dyslexia: cultural diversity and biological unity. Science, Perani, D., Cappa, S. F., Tettamanti, M., Rosa M., Scifo, P., Mozzo, A., Basso, A. & Fazio, F. (2003). A fMRI study of word retrieval in aphasia. Brain and Language, Small S. L., Nusbaum H. C. (2004). On the neurobiological investigation of language understanding in context. Brain and Language, 89(2):300-11. List of speakers and talks Moderator: Steven Small Introduction Steven Small and Katiuscia Sacco