Résumé
Objective: The present study aimed to elucidate the neural correlates of
the deafferentation cognitive model of verbal perseveration (VP) by
analyzing the connectomics of the sites where electrical stimulation
elicited VP during awake left glioma surgery. Methods: We retrospectively
reviewed the anatomical sites that generated VP when electrically
stimulated, in a series of 21 patients operated on while awake for a left
glioma. Each stimulation point was manually located on the postoperative
MRI and then registered to the Montreal Neurological Institute template.
Connectomics of these sites were further analyzed using Tractotron and
disconnectome maps. Results: VP stimulation sites were located within the
white matter surrounding the postero-superior head of the caudate nucleus,
as well as within the white matter of the external capsule and the
supero-lateral wall of the temporal horn of the ventricle. Furthermore,
tractotron and disconnectome maps revealed the connectome of these
stimulation sites: the inferior fronto-occipital fasciculus,
fronto-striatal tract, and anterior thalamic radiations. Conclusion: Based
on these results and other data, we propose the following anatomical
implementation of the deafferentation cognitive model: the lexico-semantic
system – comprising different areas linked together through direct
cortico-cortical connections – sends information to the striatum; the
striato-thalamic system acts as a tunable filter of this lexico-semantic
input; and the thalamus projects back to the lexico-semantic system,
amplifying the targeted response and inhibiting its competitors.