Cartographier la perception des phonèmes du français

Sans que nous en ayons conscience, notre cerveau accomplit un exploit chaque fois que nous écoutons quelqu'un parler : traduire le son perçu en une série d'unités linguistiques, les phonèmes, tout en faisant abstraction du bruit environnant. Mais sur quelles caractéristiques des sons de parole s’appuie-t-il pour réaliser cette tâche ? Par exemple : quels sont les indices acoustiques qui nous permettent de distinguer les mots bas, tas, pas, gars ou cas, ne différant que par leur phonème initial ?

La fabrique du sens : comment le cerveau compose-t-il des mots ?

Le décodage cérébral comme méthode de dissection du traitement du langage. 

Ces deux études utilisent une même méthode : celle du décodage de l'activité cérébrale par magnétoencéphalographie (MEG). Cette technique non-invasive permet de mesurer les champs magnétiques générés par l'activité neuronale dans le cortex: lorsque les neurones s’activent, les courants électriques génèrent instantanément des champs magnétiques.

Investigating the human binocular visual system using multi-modal magnetic resonance imaging

Seeing in stereoscopic depth relies on the slight differences in the images in the two eyes resulting from their horizonal separation. As the inputs from the eyes are first combined in the primary visual cortex (V1), human brain imaging can be used to investigate the earliest stages of processing. To perceive depth, binocular neurons in V1 need balanced input from the two eyes, likely established by mutual inhibition, whereby activation of one eye inhibits the other eye. Thus, when input from the two eyes is comparable, both will contribute equally to binocular vision to promote 3D vision.

Understanding the development of the human brain in the absence of vision 

In the rare case that both eyes fail to develop, there is a complete absence of light input to the visual system at all stages of development. This raises the question of how the brain utilises the cortical and subcortical areas that would usually process visual information. It has been shown in a number of studies that the ‘visual cortex’ of congenitally blind people is used to process ‘high-level’ auditory information such as language. In this talk I will present a series of fMRI studies in which we attempt to understand how auditory information reaches the occipital lobe.

The potential for visual rehabilitation following stroke to the visual cortex 

While damage to the primary visual cortex, often due to a stroke, leads to loss of the visual field contralateral to the damaged cortex, there are currently few opportunities for rehabilitation. In my previous talk I laid out how we have used multi-modal MRI to uncover the pathways likely to be carrying visual information after damage to primary visual cortex. The aim of this talk, therefore, is to consider the effects of visual training on both behavioural and neural structures.

Understanding ‘blindsight’: investigating the pathways that allow those who are clinically blind to ‘see’

Damage to the primary visual cortex leads to loss of the visual field contralateral to the damaged cortex. However, in spite of this loss, some patients are still able to detect visual information about stimuli presented within their blind field. A growing area of research aims to exploit this residual visual function to try to improve visual performance through rehabilitation programmes stimulating the blind field. However, to optimise such programmes it is important to understand the pathways through which this information is conveyed.

S'abonner à