Seminaire: Ingo Hertrich, GIPSA-Lab, Grenoble, 11 avril 2013

[Thierry Hamon]

Date: Thu, 7 Mar 2013 16:53:16 +0100
From: Rosario Signorello <rosario.signorello at gipsa-lab.grenoble-inp.fr>
Message-ID: <CAGxnMbWtC35-6tk-bYEGehpafY6pUbr=rGvk9iMJ4PWwNF-uCA at mail.gmail.com>
X-url: http://www.gipsa-lab.grenoble-inp.fr/animation/seminaires.php?id_sem=416


Bonjour à tous,

Monsieur Ingo Hertrich du Hertie Institute for Clinical Brain Research,
Dpt of General Neurology, University of Tuebingen, viendra nous
présenter ses travaux sur :

"Speech perception in the brain and the contribution of audiovisual
pathways to speed up this process"

Date : Jeudi  11/04/2013 à 13h30
Lieu : GIPSA-lab, Département Parole & Cognition, salle B314 du site
Ampère
Plan d'accès : http://www.gipsa-lab.grenoble-inp.fr/plan-d-acces.php

Résumé :
Blind subjects show visual cortex activation during the perception of
accelerated speech (> 16 syllables/s) largely unintelligible to sighted
subjects. This activation seems to be functionally relevant for speech
understanding, improving the temporal resolution of speech
perception. Furthermore, it seems to reflect an early perceptual
processing mechanism since it is time-locked to the syllable onsets of
the incoming speech signal. In sighted individuals, the "bottleneck" for
time-compressed speech comprehension is located in frontal rather than
temporoparietal cortex whereby the supplementary motor area (SMA) seems
to play a particular role. Thus, we have to build up a model of speech
perception that includes the SMA as an interface of perceptual input
processing with frontal speech generation and working memory
structures. Considering the function of the SMA in speech motor control,
this signal seems to be a kind of prosodic pacemaker. In normal speech
perception, presumably, a syllabic pacing signal can easily be derived
from a phase-locked representation of the speech envelope in right
auditory cortex, synchronizing predictive and incoming phonological
information. This mechanism might have a temporal limit at ca. 15 Hz,
i.e. approximately the frequency at which periodic events become
attributed with an audible pitch percept. Blind subjects seem to
overcome this limit of the auditory system by using right visual cortex
to provide the SMA with a syllabic trigger signal.  This early
signal-related syllabic representation seems to be transferred to visual
cortex directly from the afferent auditory pathway via superior
colliculus and pulvinar. In sighted individuals, this pathway might not
be available since it is engaged in actual audiovisual functions.

Voici l'affichage virtuel du séminaire de M Ingo Hertrich :
http://www.gipsa-lab.grenoble-inp.fr/animation/seminaires.php?id_sem=416

Pour plus d'informations sur les séminaires du Département parole et
cognition du GIPSA-lab :
http://www.gipsa-lab.grenoble-inp.fr/animation/seminaires.php?dep=dpc

Rosario Signorello
pour l'équipe séminaire du Département Parole et Cognition du GIPSA-lab

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