Stable Modality-Specific Activity Flows As Reflected by the Neuroenergetic Approach to the fMRI Weighted Maps

This article uses the ideas of neuroenergetic and neural field theories to detect stimulation-driven energy flows in the brain during face and auditory word processing. In this analysis, energy flows are thought to create the stable gradients of the fMRI weighted summary images. The sources, from which activity spreads in the brain during face processing, were detected in the occipital cortex. The following direction of energy flows in the frontal cortex was described: the right inferior frontal = >the left inferior frontal = >the triangular part of the left inferior frontal cortex = >the left operculum. In the left operculum, a localized circuit was described. For auditory word processing, the sources of activity flows were detected bilaterally in the middle superior temporal regions, they were also detected in the left posterior superior temporal cortex. Thus, neuroenergetic assumptions may give a novel perspective for the analysis of neuroimaging data

Effect of Audiovisual Training on Monaural Spatial Hearing in Horizontal Plane

The article aims to test the hypothesis that audiovisual integration can improve spatial hearing in monaural conditions when interaural difference cues are not available. We trained one group of subjects with an audiovisual task, where a flash was presented in parallel with the sound and another group in an auditory task, where only sound from different spatial locations was presented. To check whether the observed audiovisual effect was similar to feedback, the third group was trained using the visual feedback paradigm. Training sessions were administered once per day, for 5 days. The performance level in each group was compared for auditory only stimulation on the first and the last day of practice. Improvement after audiovisual training was several times higher than after auditory practice. The group trained with visual feedback demonstrated a different effect of training with the improvement smaller than the group with audiovisual training. We conclude that cross-modal facilitation is highly important to improve spatial hearing in monaural conditions and may be applied to the rehabilitation of patients with unilateral deafness and after unilateral cochlear implantation

Can mismatch negativity be linked to synaptic processes? A glutamatergic approach to deviance detection.

International audienceThis article aims to provide a theoretical framework to elucidate the neurophysiological underpinnings of deviance detection as reflected by mismatch negativity. A six-step model of the information processing necessary for deviance detection is proposed. In this model, predictive coding of learned regularities is realized by means of long-term potentiation with a crucial role for NMDA receptors. Mismatch negativity occurs at the last stage of the model, reflecting the increase in free energy associated with the switching on of silent synapses and the formation of new neural circuits required for adaptation to the environmental deviance. The model is discussed with regard to the pathological states most studied in relation to mismatch negativity: alcohol intoxication, alcohol withdrawal, and schizophrenia

Face categorization

categorization of social features based on face informatio

Sensory stimulation induces tensor fields, which specifically transform brain activity.

International audience: It was recently shown that brain activity can be represented as a stimulation-specific vector field. Since the vector field of brain activity is specifically transformed by sensory input, we suggested that a tensor field that transforms brain activity reflects sensory input. We calculated the tensor fields that transform brain activity between visual baseline and auditory word processing in PET data and between environmental sounds and auditory word processing in fMRI data. In the first comparison, significant clusters formed a distributed network over the brain cortex. In the second comparison, clusters that were more localised in the temporo-frontal network of speech processing. Our study therefore demonstrated that tensor fields reflect the sensory input that specifically transforms brain activity

Schizophrenia and language - Shall we look for a deficit of deviance detection?

International audienceIn this article, we consider the view on schizophrenia that asserts this disease originates from a deficit in the hemispheric specialization for language. We suggest that a deficit in the hemispheric specialization for language may be a consequence of the other recently shown neurophysiological deficit of schizophrenia, namely deviance detection. We hypothesise that a deficit of deviance detection related to the dysfunction of NMDA receptors in schizophrenia leads to the abnormal interaction between the parallel and sequential streams of speech processing in the brain. This hypothesis opens perspectives for genetic, molecular and pharmacological studies of the deficit of deviance detection in schizophrenia, as reflected by event-related potentials and neuroimaging during speech processing

Data

Data from the stop-signal experiment in the auditory, visual and audiovisual modaliies

Neuroimaging and neuroenergetics: Brain activations as information-driven reorganization of energy flows.

International audienceThere is increasing focus on the neurophysiological underpinnings of brain activations, giving birth to an emerging branch of neuroscience - neuroenergetics. However, no common definition of "brain activation" exists thus far. In this article, we define brain activation as the information-driven reorganization of energy flows in a population of neuroglial units that leads to an overall increase in energy utilization in this population. On the basis of this definition, the key aspects of modern biochemical and biophysical approaches to neuroenergetics are considered from the perspective of the links between these approaches within the context of the free energy minimization principle and the neurophysiological conception of deviance detection. In this light, we consider brain basal activity as subserving internal representations of the environment (predictive coding), and brain activation as reflecting the level of deviance from predictive coding

Activation-verification in continuous speech processing: Interaction of cognitive strategies as a possible theoretical approach

International audienceThis article presents an activation–verification approach to the problem of continuous speech processing in the brain. The presented model consists of two streams of processing: sequential and parallel. The sequential stream is strictly modular; the parallel stream is highly interactive and creates predictive coding variants based on initially missing linguistic information. The parallel stream predictions are incrementally verified, accepted, or rejected on the basis of the actual linguistic information perceived by the sequential stream. In this model, the brain's continuous speech processing, regarded as a whole, remains uninterrupted due to the functioning of the parallel stream. We discuss the possible application of the model to the problem of hemispheric asymmetry as reflected by studies of brain lesions and functional neuroimaging

A deficit in deviance detection is not specific but plays a key role in schizophrenia: Reply to Van den Noort et al.

International audienc