Functional Topography of Auditory Areas Derived From the Combination of Electrophysiological Recordings and Cortical Electrical Stimulation

Abstract

The posterior part of the superior temporal gyrus (STG) has long been known to be a crucial hub for auditory and language processing, at the crossroad of the functionally defined ventral and dorsal pathways. Anatomical studies have shown that this “auditory cortex” is composed of several cytoarchitectonic areas whose limits do not consistently match macro-anatomic landmarks like gyral and sulcal borders. The only method to record and accurately distinguish neuronal activity from the different auditory sub-fields of primary auditory cortex, located in the tip of Heschl and deeply buried in the Sylvian fissure, is to use stereotaxically implanted depth electrodes (Stereo-EEG) for pre-surgical evaluation of patients with epilepsy. In this prospective, we focused on how anatomo-functional delineation in Heschl’s gyrus (HG), Planum Temporale (PT), the posterior part of the STG anterior to HG, the posterior superior temporal sulcus (STS), and the region at the parietal-temporal boundary commonly labeled “SPT” can be achieved using data from electrical cortical stimulation combined with electrophysiological recordings during listening to pure tones and syllables. We show the differences in functional roles between the primary and non-primary auditory areas, in the left and the right hemispheres. We discuss how these findings help understanding the auditory semiology of certain epileptic seizures and, more generally, the neural substrate of hemispheric specialization for language.

New stimulation procedures for language mapping in stereo‐EEG

“…Regarding notable regional aspects, in the PLR, the IFS showed an increased capacity to induce a language deficit without confounding auditory phenomena associated with AD, which is particularly valuable in mapping this specific region. In the PLR, the repetition task emerged as highly useful (clinical deficit detection 66.7%, followed by naming 57.1%, or reading 50.8%), concordant with the observations of other authors, 4,5,15 despite this region being widely recognized as a comprehension hub.…”

“…Anatomically, language regions were defined as follows: 4,12,13,14 Anterior language region (ALR): pars opercularis or triangularis. Posterior language region (PLR): (1) superior temporal gyrus, from the end of the central sulcus extending posteriorly until the end of the sylvian fissure, including the sylvian‐parietotemporal region 15 ; and (2) posterior temporal sulcus with the same anteroposterior limits. We did not include contacts in Heschl gyrus, invariably associated with auditory phenomena, neither in the planum temporale 15 Basal language region (BLR): fusiform gyrus and the surrounding mesial and lateral sulci, anteriorly from the pole, and posteriorly to the temporo‐occipital junction (1–9 cm from the tip of the temporal pole) 13,14 …”

Tinnitus Perception in Light of a Parietal Operculo–Insular Involvement: A Review

“…This technique provides a direct link between perception and anatomical location, as long as the emergence of perceptions occurs. It has been used in vivo to help delineate the precise boundaries of the human primary auditory cortex on Heschl's Gyrus [46].…”