Research 

Research Overview

My program of research focuses on understanding the neural basis of olfactory perception and how olfactory perception is modulated by learning and normal or pathological aging. We are also interested in how olfaction can modulate affective function such as anxiety. 

Research 

Odorants play an important role in many aspects of life such as social interactions (mother–infant attachment, sexual behavior), navigation, alarm signals detection and recognition (smoke, rotten food, predators), or food intake. I am investigating how the brain responds to olfactory experiences in order to guide the behavior. To achieve this, we use a variety of methods ranging from behavioral tests, optogenetics, brain imaging, morphological 3D analysis of neurons… 

The main ongoing projects: 

1- Understanding the neural basis of odor hedonics

One major aspect of olfactory perception is hedonics. Indeed, as you smell an odorant, your first reaction will certainly be either I like or I dislike this smell. This primary function of olfaction guides approach or avoidance to stimuli. We investigate how our brain dictates us to like and thus approach an odorant. We reported that the olfactory bulb, the first cortical relay of olfactory information processing, carries a neural signature of odor hedonic value. We are now investigated in how this hedonic information is processed in higher olfactory centers and reward system to drive behavior. We also study how the  experience-dependent changes in hedonic value are encoded in the olfactory pathway. 

Impairments in odor hedonics with normal aging may affect quality of life in a way that is not anecdotal. They affect social interactions, impair hedonic responses to food odors and decrease the pleasure of eating and food intake. This can lead to social isolation and bodily wasting disorders (common in aging and age-related dementias) and represents a major public health problem. We are working on the mechanisms responsible for the alteration of brain odor hedonics with aging. 

2- Why the odor of Rose is such attractive? 

Roses have been domesticated since Antiquity for their perfume. Greeks, Romans, Persians, and Chineses grow roses since at least 2000 years. All over the world, no other plant has followed the human history for this hedonic reason. Indeed, this is the only example of plant domestication for the human delight, all the others being domesticated for food (rice, corn, wheat…). For the plant itself, this is an evolution success. So why the odor of roses is able to induce such strong positive emotional reaction? Why and how our brain dictates us to like rose perfume? In this project, we investigate the odorant molecules that are the most attractive in the rose odor and we will look for whether the reward circuit is involved in odor attractiveness. 

3- Understanding the neural mechanisms underlying odor impairment by early life adversity

A major risk factor of depression in adults is childhood trauma. Indeed, neglect early in life causes developmental brain disorders that have a long term effect on the emotional state. There is a mouse model that mimics this pathology: the model of early life adversity induced by maternal separation. In this project, we will investigate the neural bases underlying impairments in olfactory perception after early life adversity-induced and how olfactory remediation can improve olfactory perception and well beeing. 

5- The "Proust effect": how do olfactory memories of childhood persist in adults? 

Marcel Proust, in his book Swann’s Way, describes the smell of a madeleine dipped in a lime blossom infusion as triggering intense joy and childhood memories. It appears that autobiographical memory associated with odors is older, that is, it goes back further into childhood than memory associated with other sensory modalities such as visual or auditory ones, and that it is generally linked to positive events.

This project has two main objectives. First, we will set up a participatory survey on a national and then international scale in order to study the emergence of the earliest olfactory memories, their positive nature, or the memories with which they are associated. Second, in order to understand how this olfactory memory is formed in childhood and maintained into adulthood, we will develop an animal model.

We hypothesize that the olfactory bulb, a key structure in olfactory information processing and olfactory memory, is a hub of this memory. We will focus particularly on a population of neurons known to be highly plastic and to persist throughout life, whereas others are replaced. Thus, this project will help us better understand how the brain underlies the persistence of this very powerful olfactory memory.

phD students and post-docs

Dr. Kevin Bath (Columbia Univ.)

Drs. Sylvie Baudino and Jean-Claude Caissard (Univ. Jean Monnet)

Dr Didier (Neuropop)

Dr. Christiane Linster (Cornell Univ.)

Dr Bensafi (Neuropop)

Dr. Olivier Raineteau (SBRI)

Dr Richard (Neuropop)

Dr. Dan Wesson (Univ. of Florida)

Dr. Pierre-Hervé Luppi (CRNL)

Dr Jérome Brunelin (CRNL)

Research supported by

CNRS; Inserm; Lyon 1 University; Région Rhône Alpes (APP Ambition Recherche), Labex Cortex, NrJ Fondation, IRP CNRS, FRM, B2V, ANR