Ce que les réponses sensorielles nous enseignent sur l’anorexie mentale

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Pleasure for visual and olfactory stimuli evoking energy-dense foods is decreased in anorexia nervosa.

International audienceAlthough patients with anorexia nervosa have been suggested to be anhedonic, few experiments have directly measured their sensory pleasure for a range of food and non-food stimuli. This study aimed to examine whether restrictive anorexia nervosa (AN-R) patients displayed: i) a generalized decline in sensory pleasure or only in food-related sensory pleasure; ii) a modification of hedonic responses to food cues (liking) and of the desire to eat foods (wanting) as a function of their motivational state (hunger vs. satiety) and energy density of foods (high vs. low). Forty-six female participants (AN-R n=17; healthy controls (HC) n=29) reported before/after lunch their pleasure for pictures/odorants representing foods of different energy density and non-food objects. They also reported their desire to eat the foods evoked by the sensory stimuli, and completed the Physical Anhedonia Scale and the Beck Depression Inventory. AN-R and HC participants did not differ on liking ratings when exposed to low energy-density food or to non-food stimuli. The two groups also had similar physical anhedonia scores. However, compared to HC, AN-R reported lower liking ratings for high energy food pictures regardless of their motivational state. Olfactory pleasure was reduced only during the pre-prandial state in the AN-R group. The wanting ratings showed a distinct pattern since AN-R participants reported less desire to eat the foods representing both low and high energy densities, but the effect was restricted to the pre-prandial state. Taken together these results reflect more the influence of core symptoms in anorexia nervosa (fear of gaining weight) than an overall inability to experience pleasure

Neural correlates of food odors: "liking" and "wanting" reward network

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Hedonic reactivity to visual and olfactory cues: rapid facial electromyographic reactions are altered in anorexia nervosa.

IDS Number: 745AYInternational audienceThough it has been suggested that hedonic processing is altered in anorexia nervosa (AN), few studies have used objective measures to assess affective processes in this eating disorder. Accordingly, we investigated facial electromyographic, autonomic and subjective reactivity to the smell and sight of food and non-food stimuli, and assessed more particularly rapid facial reactions reflecting automatic processing of pleasantness. AN and healthy control (HC) women were exposed, before and after a standardized lunch, to pictures and odorants of foods differing in energy density, as well as to non-food sensory cues. Whereas the temporal profile of zygomatic activity in AN patients was typified by a fast drop to sensory cues within the 1000 ms following stimulus onset, HC showed a larger EMG reactivity to pictures in a 800-1000 ms time window. In contrast, pleasantness ratings discriminated the two groups only for high energy density food cues suggesting a partial dissociation between objective and subjective measures of hedonic processes in AN patients. The findings suggest that the automatic processing of pleasantness might be altered in AN, with the sensitivity to reward being modulated by controlled processes

The Neural networks underlying the liking and wanting responses to food odors are modified in anorexia nervosa

International audienc

The Neural networks underlying the liking and wanting responses to food odors are modified in anorexia nervosa

International audienc

Schéma d'amplification d'impulsions femtosecondes dans une fibre multicœur par combinaison spectrale cohérente

National audienceUn schéma compact pour l'amplification d'impulsions femtosecondes par une fibre amplificatrice multicoeur est proposé ici. Un élément dispersif sépare spatialement les différentes composantes spectrales qui sont amplifiées séparément dans les coeurs d'une même fibre optique avant d'être recombinées en sortie du dispositif à l'aide d'un second élément dispersif. L'amplification en parallèle de bandes spectrales étroites permet de diminuer le rétrécissement spectral par le gain et ainsi de pouvoir obtenir des impulsions brèves et énergétiques. Un contrôle de la phase des différentes bandes spectrales par un élément actif permet de retrouver une durée d'impulsion proche de celle de l'impulsion initiale. Ainsi, nous démontrons la reconstruction d'une impulsion brève de 250fs après propagation de ses composantes spectrales dans les 5 coeurs indépendants d'une même fibre

Spatially dispersive scheme for transmission and synthesis of femtosecond pulses through a multicore fiber

International audienceA new scheme is presented for fiber transmission of ultrashort laser pulses. A dispersive device divides the input pulses into spatially separated spectral components which are individually launched in the different channels of a multicore fiber before being recombined at the output by a second dispersive device. The parallel transmission of narrow spectral bands avoids self-phase modulation and could be appropriate to deliver high peak power pulses. Phase management of the spectral bands by an active element offers recovery of the seed pulse duration at the fiber output as well as pulse shaping capabilities. Both are reported in a proof of concept experiment using 190 fs input pulses and a 5 cores polarization maintaining fiber. Extension of the concept to femtosecond pulses amplification is suggested