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Brain substrates of language functions: advances and limitations of neuroimaging| old_uid | 6564 |
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| title | Brain substrates of language functions: advances and limitations of neuroimaging |
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| start_date | 2009/03/23 |
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| schedule | 11h-12h30 |
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| online | no |
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| summary | The explosion of new brain imaging techniques and methods has revolutionized our knowledge of the brain substrates of language functions and even the earlier clinical anatomical method in aphasic patients can now be renewed by complementing the study of lesion topography with that of possibly compensatory processes in spared territories. In addition, brain imaging has made it possible to explore the biological substrates of language disorders apparently not associated with any visible lesion such as developmental disorders (eg dyslexia). In spite of these spectacular advances we are still very far from approaching the fine-grained neurophysiology of language processes and the ability to study language in close-to-natural conditions. Some limitations are technological, ie the spatial resolution is limited even with high-field MRI magnets and there is no technique able to resolve space and time at the desirable level. It follows that meta-analyses of literature data frequently end up with a pattern of great overlap of diverse functions in relatively narrow regions eg ‘Broca’s area’. An even more challenging difficulty is linked to inter-subject variability in the measured signals in a given experiment. Yet another difficulty is linked to the distribution over large and distant territories of fugacious events related to processes at stake; studying this connectivity in real time remains a difficult challenge.
Beyond these technical difficulties, there are also limitations linked to our ignorance of the ‘neural code’ that might be active in key-regions for a given language-related process ; indeed the current methods only allow us to record weak signals from the brain activity that are somewhat modulated by experimental conditions. It follows that one important feature for cognitive neuroscience is to study in a systematic way the relationships between the variation of cognitive performance and those of brain activity.
Rather than being a source of discouragement, these current limitations allow one to sketch out (probably) endless future research programs. |
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| responsibles | Waszak |
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