Domain-specific reorganization of semantic processing after extensive damage to the left temporal lobe.
We investigated with fMRI the cortical correlates of recovery of semantic processing in a patient (DL) with left temporal damage. Names of animals, plant, and artifacts (semantic conditions) and reversed words (baseline condition) were auditorily presented to the patient and nine control subjects in a category monitoring task. Data analyses showed large differences between the patterns of domain-specific semantic activation observed in DL and the control subjects, which could be attributed to a cortical reorganization compensating for the damaged part of the semantic processing system in DL. Such reorganization relied on three main mechanisms, first, upholding of a subset of the structurally intact domain-specific regions, second, functional changes (both decreases and increases) of the domain specificity in several structurally intact regions that are normally engaged in the domain-specific network and, third, recruitment of supplementary domain-specific areas. Thus, in DL, animal-specific processing engaged supplementary areas in the left lingual gyrus and right cuneus, which correspond to animal-specific regions usually engaged in more demanding semantic tasks whereas the supplementary areas recruited for artifact-specific processing within the left superior/middle occipital lobe and right angular gyrus probably are endowed with a related but not domain-specific, semantic function. In contrast, no supplementary area contributed to plant-specific processing in DL. These findings suggest that the pattern of cortical reorganization consecutive to damage to the semantic processing network depends on the particular domain-specific function sustained by the damaged areas and the capacity of the remaining areas to assume this function.
Léonard
Bénédicte
B
Université catholique de Louvain, Louvain-la-Neuve, Belgium.
de Partz
Marie-Pierre
MP
Grandin
Cécile
C
Pillon
Agnesa
A
D001307:Auditory Perception; D001931:Brain Mapping; D004660:Encephalitis / Q000503:physiopathology*; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D012660:Semantics; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000503:physiopathology*