Biomedical subjects

Denis LeBihan

Publications and source records attributed to Denis LeBihan.

4 recordsLinked to original sources

PubMed2006

Brain structure predicts the learning of foreign speech sounds.

Previous work has shown a relationship between parietal lobe anatomy and nonnative speech sound learning. We scanned a new group of phonetic learners using structural magnetic resonance imaging and diffusion tensor imaging. Voxel-based morphometry indicated higher white matter (WM) density in left Heschl's gyrus (HG) in faster compared with slower learners, and manual segmentation of this structure confirmed that the WM volume of left HG is larger in the former compared with the latter group. This finding was replicated in a reanalysis of the original groups tested in Golestani and others (2002, Anatomical correlates of learning novel speech sounds. Neuron 35:997-1010). We also found that faster learners have a greater asymmetry (left > right) in parietal lobe volumes than slower learners and that the right insula and HG are more superiorly located in slower compared with faster learners. These results suggest that left auditory cortex WM anatomy, which likely reflects auditory processing efficiency, partly predicts individual differences in an aspect of language learning that relies on rapid temporal processing. It also appears that a global displacement of components of a right hemispheric language network, possibly reflecting individual differences in the functional anatomy and lateralization of language processing, is predictive of speech sound learning.

Adolescent↗

PubMed2004

Reference frames for spatial cognition: different brain areas are involved in viewer-, object-, and landmark-centered judgments about object location.

Functional magnetic resonance imaging was used to compare the neural correlates of three different types of spatial coding, which are implicated in crucial cognitive functions of our everyday life, such as visuomotor coordination and orientation in topographical space. By manipulating the requested spatial reference during a task of relative distance estimation, we directly compared viewer-centered, object-centered, and landmark-centered spatial coding of the same realistic 3-D information. Common activation was found in bilateral parietal, occipital, and right frontal premotor regions. The retrosplenial and ventromedial occipital-temporal cortex (and parts of the parietal and occipital cortex) were significantly more activated during the landmark-centered condition. The ventrolateral occipital-temporal cortex was particularly involved in object-centered coding. Results strongly demonstrate that viewer-centered (egocentric) coding is restricted to the dorsal stream and connected frontal regions, whereas a coding centered on external references requires both dorsal and ventral regions, depending on the reference being a movable object or a landmark.

Adult↗

PubMed2003

Phonological grammar shapes the auditory cortex: a functional magnetic resonance imaging study.

Languages differ depending on the set of basic sounds they use (the inventory of consonants and vowels) and on the way in which these sounds can be combined to make up words and phrases (phonological grammar). Previous research has shown that our inventory of consonants and vowels affects the way in which our brains decode foreign sounds (Goto, 1971; Näätänen et al., 1997; Kuhl, 2000). Here, we show that phonological grammar has an equally potent effect. We build on previous research, which shows that stimuli that are phonologically ungrammatical are assimilated to the closest grammatical form in the language (Dupoux et al., 1999). In a cross-linguistic design using French and Japanese participants and a fast event-related functional magnetic resonance imaging (fMRI) paradigm, we show that phonological grammar involves the left superior temporal and the left anterior supramarginal gyri, two regions previously associated with the processing of human vocal sounds.

Acoustic Stimulation↗

PubMed2002

Monitoring disease progression in CADASIL with diffusion magnetic resonance imaging: a study with whole brain histogram analysis.

BACKGROUND AND PURPOSE: In cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a large increase in water diffusion has been found both inside and outside the cerebral lesions as detected on conventional MRI. The aim of the present study was to assess the sensitivity of diffusion tensor imaging for monitoring the progression of cerebral tissue damage during the course of CADASIL. METHODS: With the use of diffusion tensor imaging, whole brain trace of the diffusion tensor [Trace(D)] histograms were obtained in 22 CADASIL patients and 12 age-matched controls at baseline, in 14 patients after a mean delay of 21 months, and in 5 controls after a mean delay of 29 months. Parameters derived from these histograms (mean value, peak height, and peak location) were analyzed at baseline and during the follow-up. RESULTS: At baseline, all the histogram parameters differed between patients and controls and were found to be significantly correlated with both the Mini-Mental State Examination score and Rankin Scale score in the patient group. The follow-up study showed a decrease in the peak height associated with an increase in the mean value of whole brain Trace(D) histograms in the 14 CADASIL patients scanned twice. The diffusion changes appeared larger in the patients whose Rankin score increased during the study period. CONCLUSIONS: These results suggest that the measurement of water diffusion over time is a sensitive marker for the progression of tissue damage in the brain. Thus, quantitative diffusion MRI can be used to monitor disease progression in CADASIL and possibly in other types of small-vessel brain disorders.

Adult↗