Global / local integration and corpus callosum : anatomical and behavioural study of case of allgrove syndrome (triple-a syndrome)
Mr Stuart NASHa, Prof Gilles RODEa, Mrs Annik CHARNALLETb
a Hôpital Henry Gabrielle, Hospices Civiles de Lyon, b CMRR et Neuropsychologie, Pôle de psychiatrie et neurologie, CHU de Grenoble
Visuospatial perception is a complex ability, with various aspects. We are continuously integrating different information, like when our brain processes visual information from left and right hemisphere, in order to form a single and unitary image. The processing of visuospatial information, and more specifically its global / local aspect, has led to many studies, indicating the active involvement of the corpus callosum.
Objective: to study the influence of an alteration of the corpus callosum on the integration of global / local information
Methods: C.M. presents an Allgrove syndrome1, likely a pathology of white matter fibres. This patient, with a singular neuropsychological profile, is partially impaired in global and local information integration and shows a corpus callosum alteration. This research, a case-study with a group of 6 matched control subjects, relied on a two-level approach, anatomical (MRI-DTI) and behavioural, using a hierarchical letter paradigme2
Results: despite all the precautions needed regarding the interpretation of our results, some specificities are emphasized : at an anatomical level, we note, for C.M., a microscopic alteration of her corpus callosum ; the results from our behavioural protocol show, for C.M., a higher precedence effect, a greater sensibility to interference and a facilitation effect more important
Discussion: these different results, never reported before in this pathology, indicates, for C.M., an impairment in global / local integration associated with a corpus callosum alteration. This alteration, probably part of a more global degenerative process linked to her pathology, shows the relevance of an extended neuropsychological assessment coupled to a DTI study, in order to better understand impairments generally appearing in neuropsychological rehabilitation.
1 - Allgrove, J., Clayden, G., Grant, D. & Macauley, J. Familial glucocorticoid deficiency with achalasia of the cardia and deficient tear production. Lancet 1978;8077 ;1284-1286
2- Mueller-Oehring, E., Schulte, T., Raassi, C., Pfefferbaum, A., Sullivan, E. Local-global interference is modulated by age, sex and anterior corpus callosum size. Brain Research 2007; 1142:189-205
Keywords : Visuospatial processing, global / local integration, corpus callosum, Allgrove syndrome, Diffusion tensor imaging (DTI)