The left inferior frontal gyrus under focus: an fMRI study of the production of deixis via syntactic extraction and prosodic focus: An fMRI study of the production of deixis

International audienceThe left inferior frontal gyrus (LIFG, BA 44, 45, 47) has been associated with linguistic processing (from sentence- to syllable- parsing) as well as action analysis. We hypothesize that the function of the LIFG may be the monitoring of action, a function well adapted to agent deixis (verbal pointing at the agent of an action). The aim of this fMRI study was therefore to test the hypothesis that the LIFG is involved during the production of agent deixis. We performed an experiment whereby three kinds of deictic sentences were pronounced, involving prosodic focus, syntactic extraction and prosodic focus with syntactic extraction. A common pattern of activation was found for the three deixis conditions in the LIFG (BA 45 and/or 47), the left insula and the bilateral premotor (BA 6) cortex. Prosodic deixis additionally activated the left anterior cingulate gyrus (BA 24, 32), the left supramarginal gyrus (LSMG, BA 40) and Wernicke's area (BA 22). Our results suggest that the LIFG is involved during agent deixis, through either prosody or syntax, and that the LSMG and Wernicke's area are additionally required in prosody-driven deixis. Once grammaticalized, deixis would be handled solely by the LIFG, without the LSMG and Wernicke's area

Réorganisation du conduit vocal et réorganisation corticale de la parole : de la perturbation aux lèvres à la glossectomie. Études acoustiques et IRMf

21 pagesRetrouver l'usage de la langue - articulateur central de la parole - pour produire les dix voyelles du français, et ce après une opération de glossectomie suivie d'une reconstruction linguale à base d'un muscle de la cuisse (le gracilis), tel était le difficile problème que le patient K.H. (53 ans) a su résoudre au bout de neuf mois. Comment a-t-il pu apprendre à contrôler sa nouvelle " langue" pour produire les différentes voyelles de façon distincte ? C'est ce que nous avons cherché à comprendre dans cette étude. Nous avons mis en place un suivi expérimental longitudinal du patient en enregistrant ses productions acoustiques et son activité cérébrale juste avant l'opération, un mois après l'opération et neuf mois après l'opération. Nous avons ainsi pu suivre la récupération corticale du sujet, en l'occurrence la re-latéralisation dans l'hémisphère gauche pour l'articulation des catégories vocaliques de sa langue, en relation avec l'amélioration de ses performances articulatoires et acoustiques. Plus fondamentalement, cette prouesse atteste de la plasticité corticale phonologique via l'équifinalité compensatoire du système de la langue, en l'occurrence par le jeu des équivalence motrices et acoustiques

Cerebral correlates of multimodal pointing: An fmri study of prosodic focus, syntactic extraction, digital- and ocular- pointing

International audienceDeixis or pointing plays a crucial role in language acquisition and speech communication and can be conveyed in several modalities. The aim of this paper is to explore the cerebral substrate of multimodal pointing actions. We present an fMRI study of pointing including: 1) index finger pointing, 2) eye pointing, 3) prosodic focus production, 4) syntactic extraction (during speech production). Fifteen subjects were examined while they gave digital, ocular and oral responses inside the 3T imager. Results of a random effect group analysis show that digital and prosodic pointings recruit the parietal lobe bilaterally, while ocular and syntactic pointings do not. A grammaticalization process is suggested to explain the lack of parietal activation in the syntactic condition. Further analyses are carried out on the link between digital and prosodic parietal activations

Abnormal cortical sensorimotor activity during “Target” sound detection in subjects with acute acoustic trauma sequelae: an fMRI study

The most common consequences of acute acoustic trauma (AAT) are hearing loss at frequencies above 3 kHz and tinnitus. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to visualize neuronal activation patterns in military adults with AAT and various tinnitus sequelae during an auditory “oddball” attention task. AAT subjects displayed overactivities principally during reflex of target sound detection, in sensorimotor areas and in emotion-related areas such as the insula, anterior cingulate and prefrontal cortex, in premotor area, in cross-modal sensory associative areas, and, interestingly, in a region of the Rolandic operculum that has recently been shown to be involved in tympanic movements due to air pressure. We propose further investigations of this brain area and fine middle ear investigations, because our results might suggest a model in which AAT tinnitus may arise as a proprioceptive illusion caused by abnormal excitability of middle-ear muscle spindles possibly link with the acoustic reflex and associated with emotional and sensorimotor disturbances

Identifying Neural Drivers with Functional MRI: An Electrophysiological Validation

Whether functional magnetic resonance imaging (fMRI) allows the identification of neural drivers remains an open question of particular importance to refine physiological and neuropsychological models of the brain, and/or to understand neurophysiopathology. Here, in a rat model of absence epilepsy showing spontaneous spike-and-wave discharges originating from the first somatosensory cortex (S1BF), we performed simultaneous electroencephalographic (EEG) and fMRI measurements, and subsequent intracerebral EEG (iEEG) recordings in regions strongly activated in fMRI (S1BF, thalamus, and striatum). fMRI connectivity was determined from fMRI time series directly and from hidden state variables using a measure of Granger causality and Dynamic Causal Modelling that relates synaptic activity to fMRI. fMRI connectivity was compared to directed functional coupling estimated from iEEG using asymmetry in generalised synchronisation metrics. The neural driver of spike-and-wave discharges was estimated in S1BF from iEEG, and from fMRI only when hemodynamic effects were explicitly removed. Functional connectivity analysis applied directly on fMRI signals failed because hemodynamics varied between regions, rendering temporal precedence irrelevant. This paper provides the first experimental substantiation of the theoretical possibility to improve interregional coupling estimation from hidden neural states of fMRI. As such, it has important implications for future studies on brain connectivity using functional neuroimaging

Human in-vivo localized MR spectroscopy: Approaches and various results

SCOPUS: cp.jinfo:eu-repo/semantics/publishe

Spin thermodynamics in solids: Pulse techniques in pure nuclear-quadrupole-resonance spectroscopy of NaClO3

Spin thermodynamics is used to predict relations between various aspects of pulsed spectroscopy in the case of pure nuclear quadrupole resonance (NQR) of spins 32: pulse response for states of quadrupolar or dipolar order, and efficiency of transfer of quadrupolar into dipolar order by a pulse pair. Experimental results are presented on the NQR resonance of Cl35 in NaClO3 single crystals. Although there is a very satisfactory overall agreement between the observations and the predictions based on the usual assumptions underlying spin thermodynamics, experiments suggest that the choice of the quasiinvariant(s) related to the spin-spin interactions in sodium chlorate should be reconsidered. © 1984 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe