Neural bases of social contact

axis coordinated by Nathalie George

 

One of our lines of research focuses on the neural mechanisms of the processing of social signals, with a particular emphasis on the social signals conveyed by faces. Faces convey a wealth of information on others’ identity, emotional state, attention, intentions, and thoughts. The decoding of this social information is essential for adaptive behaviour in the context of interindividual interactions. How is this information coded by the human brain? How do social signals regulate human cognition and behaviour? Our studies focus on: i) The neural mechanisms of gaze perception, ii) The neural coding of emotional and social information associated with faces, iii) The sensitivity to social signals in normal and pathological conditions (e.g. depression), and iv) The impact of social contact on self consciousness and self representation.

 

Affective influence on vision

axis coordinated by Stéphanie Dubal

 

Affective stimuli enhance and facilitate perceptual processing of information. The identification of emotional stimuli is enhanced and their speed of detection shortened. Neuroimaging studies have found that emotional stimuli elicit greater activation across widespread regions in the ventral visual system than neutral pictures do. Event-Related Potentials (ERPs) studies show that some amplitude enhancement for emotional stimuli are generated in visual cortical areas in the first 100 ms post-stimulus. Such facilitation is consensually viewed as a prioritization mechanism of relevant information in the perceptual analysis to facilitate immediate and appropriate behaviour.

This raises the issue of the level(s) of interaction between affective and perceptual processing of information, and how sensory variables modulate emotional processing. The effects of emotion on perception could arise at different stages of visual processing, and more specifically, they could contribute to enhance visual discrimination. Reciprocally, sensory variables such as contrast may impact on affective experience.

We investigate the sensory contribution to affective processing, in normal controls and subjects with affective disorders. For example, we use visual contrast and make it interact with the emotional content of picture stimuli (Rey et al., 2010b). Such studies point out that not only higher level processes are modulated by affective states such as anhedonia,  but perception might also be literally coloured by affective states. Affective states may also entail modifications of early perceptual processing.

 

Biomarkers of social acceptance in depression

axis coordinated by Philippe Fossati

 

Social exclusion and sensitivity to social rejection is a risk factor for depression. One major research theme of our group is to define the biological and brain set of responses to social evaluation and to elucidate their role on the onset and maintenance of major depression.  We suggest at the neural level, that social exclusion  engages a specific  impaired cooperation of three networks (central executive network, default mode network and salience network) leading to cognitive and emotional impairment. By using pharmacological manipulation, animal model and brain imaging experiments,  we are deciphering the role of each network in the pathophysiology of major depression. Our ultimate goal is to define major depression at the biological level  in order to provide personalized treatment to depressed patients.

 

 

Brain stimulation techniques in psychiatric disorders

axis coordinated by Bruno Millet

 

We aim at articulating ICM research activity with our innovative therapeutic approach in resistant Obsessive Compulsive Disorder (OCD), in Treatment Resistant Depression (TRD) as well as potentially in addictive disorders within the new Brain Stimulation Unit (STOCAD) recently promoted and built by the Assistance Publique des Hopitaux de Paris (AP-HP). In OCD, our recent works (Millet et al. 2013; Nauczyciel et al. 2014) allow us to propose the orbito-frontal cortex (OFC) as a plausible target for rTMS. We will try to identify for each patient a neuroimaging marker (potentially prefrontal activity), in order to potentialize the efficacy of rTMS. In depression, a similar work will be driven using EEG signal as a potential marker for a better use of the neuronavigated–rTMS.  In TRD as well as in ROC (resistant OCD) we are still continuing inclusion in different randomized control trials (RCTs) of high frequency DBS assessing nucleus accumbens (Millet et al. 2014), ventral striatum and sub-thalamic nucleus (STN) as potential neuroanatomical targets. Those RCTs will be associated with Local Field Potentials recording discharge of neurons secondary to emotional auditory and facial recognition tasks as well as other cognitive tasks. These findings make crucial an improvement of implantation material, especially a great need for improvement of electrodes with more selective use in either the limbic or motor areas.