Neurophysiology of cognitive process
How does the brain represent space?
Many goal-directed behaviours of everyday life require individuals to find their way towards specific locations and ask: “Where am I?”, “Where is it?” and “How do I get there?”. We aim to address how does the brain constructs a representation of space in primates which have a very different visual system from rodents, and especially, a fovea with a high acuity at the centre of their visual field. We conduct electrophysiological recordings in the experimental model closest to human, the macaque monkey. We employ behavioural testing paradigm that uses virtual reality technology for real-time spatial navigation. Using these techniques, we showed that neurons are active for precise positions and actions related to the landmarks gazed at by the animals. Our findings indicate that counterparts of rodent place cells in primates embody multidimensional, task situated knowledge pertaining to the target of gaze. Current research focuses on neural processing beyond the hippocampus and navigation in real world.
How does the brain represent social stimuli?
To process faces, the cerebral cortex of humans and other primates has evolved dedicated areas, especially in occipito-temporal areas, in which face-selective cells underlie face identification or discrimination. Some neurons responding to faces have also been described beyond this core face processing areas. In the human hippocampus, neurons responding to faces are thought to underlie identity relevant information. Less well understood face-responsive neurons are present in the orbitofrontal cortex. We focus on different aspects of face processing in the hippocampus and the orbitofrontal cortex shedding light on the role of regions beyond the core occipito-temporal regions processing faces. For example, we showed how the activity of face selective cells in the orbitofrontal cortex encode several face dimensions that provide information about social categories and emotions. We now explore how these activities are modulated during live interactions.
Social emotions and communication
Many brain regions that have classically been associated with the evaluation of pleasant and unpleasant experiences, like the orbitofrontal cortex, insula and amygdala, also play a role in social information processing. In our laboratory, we study live social interactions between monkeys, using simple decision-making tasks in which subjects must take into account their own as well as their partner’s welfare. We also measure proxies of social communication (eye gaze patterns) and emotions (eye blinking), while recording neuronal activity in different brain regions.
Our results show that populations of neurons respond selectively to observed stimuli (such as juice rewards or unpleasant air puffs) that are delivered to a partner but not to self, other neurons exhibit the opposite selectivity, still other neurons encode stimuli delivered to both self and others. These results contribute to our understanding of the neural mechanisms underlying social emotions like empathy and provide evidence for both shared and separate substrates for representing information about self and others.
Bridging neurophysiology and ethology
The cerebral networks important for social behavior include several cortical areas within the temporal and prefrontal lobes, structures like the amygdala and hippocampus, as well as areas involved in motor processing like the premotor cortex, which are linked to the mirror neuron system. However, the fine-grained mechanisms at play within these circuits remain elusive, in large part because we lack tools to investigate brain function in a naturalistic, ethologically valid context in which social interactions could take place. We are currently developing techniques to wirelessly record brain activity in freely-moving monkeys as they perform goal-directed actions and also as they observe the actions of a conspecific or as they interact with them. Our objective is to achieve, through this novel approach bridging neurophysiology and ethology, a new understanding of how information about the social environment is acquired and represented at the neuronal and circuit levels.
Our laboratory is hosted in the Institute of Cognitive Sciences Marc Jeannerod (CNRS) in Lyon, France. It investigates the neural mechanisms underlying the spatial and social representation of the world. We use experimental tools such as intracranial electrophysiological recordings and pharmacological manipulations in non human primates to understand the computations at work during live behavior. The processes we study are at play in numerous pathological diseases from Alzheimer disease to autism.