Electrostimulation mapping of comprehension of auditory and visual words

Cortex. 2015 Oct:71:398-408. doi: 10.1016/j.cortex.2015.07.001. Epub 2015 Jul 26.

Abstract

In order to spare functional areas during the removal of brain tumours, electrical stimulation mapping was used in 90 patients (77 in the left hemisphere and 13 in the right; 2754 cortical sites tested). Language functions were studied with a special focus on comprehension of auditory and visual words and the semantic system. In addition to naming, patients were asked to perform pointing tasks from auditory and visual stimuli (using sets of 4 different images controlled for familiarity), and also auditory object (sound recognition) and Token test tasks. Ninety-two auditory comprehension interference sites were observed. We found that the process of auditory comprehension involved a few, fine-grained, sub-centimetre cortical territories. Early stages of speech comprehension seem to relate to two posterior regions in the left superior temporal gyrus. Downstream lexical-semantic speech processing and sound analysis involved 2 pathways, along the anterior part of the left superior temporal gyrus, and posteriorly around the supramarginal and middle temporal gyri. Electrostimulation experimentally dissociated perceptual consciousness attached to speech comprehension. The initial word discrimination process can be considered as an "automatic" stage, the attention feedback not being impaired by stimulation as would be the case at the lexical-semantic stage. Multimodal organization of the superior temporal gyrus was also detected since some neurones could be involved in comprehension of visual material and naming. These findings demonstrate a fine graded, sub-centimetre, cortical representation of speech comprehension processing mainly in the left superior temporal gyrus and are in line with those described in dual stream models of language comprehension processing.

Keywords: Auditory cortex; Brain tumour; Cortical mapping; Speech comprehension.

MeSH terms

  • Acoustic Stimulation
  • Adolescent
  • Adult
  • Aged
  • Attention / physiology
  • Auditory Cortex / physiology
  • Auditory Perception / physiology*
  • Brain Mapping / methods*
  • Child
  • Comprehension / physiology*
  • Discrimination, Psychological / physiology
  • Electric Stimulation*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Neurosurgical Procedures
  • Photic Stimulation
  • Reading*
  • Recognition, Psychology / physiology
  • Temporal Lobe / physiology
  • Young Adult