Olfactory preference conditioning changes the reward value of reinforced and non-reinforced odors

International audienceOlfaction is determinant for the organization of rodent behavior. In a feeding context, rodents must quickly discriminate whether a nutrient can be ingested or whether it represents a potential danger to them. To understand the learning processes that support food choice, aversive olfactory learning and flavor appetitive learning have been extensively studied. In contrast, little is currently known about olfactory appetitive learning and its mechanisms. We designed a new paradigm to study conditioned olfactory preference in rats. After 8 days of exposure to a pair of odors (one paired with sucrose and the other with water), rats developed a strong and stable preference for the odor associated with the sucrose solution. A series of experiments were conducted to further analyze changes in reward value induced by this paradigm for both stimuli. As expected, the reward value of the reinforced odor changed positively. Interestingly, the reward value of the alternative odor decreased. This devaluation had an impact on further odor comparisons that the animal had to make. This result suggests that appetitive conditioning involving a comparison between two odors not only leads to a change in the reward value of the reinforced odor, but also induces a stable devaluation of the non-reinforced stimulus

Réalisation d'un système d'émission-réception 4 canaux dédié au cerveau de rat pour un système RM à 7T

International audienceUn système ainsi qu'une bobine d'émission-réception ont été réalisés pour un système RM à 7 T. Ce système d'émission-réception 4 canaux permet de créer un champ magnétique RF B1+ polarisé circulairement. La combinaison constructive des phases des 4 canaux a été démontrée par des images RM

Parallel Odor Processing by Two Anatomically Distinct Olfactory Bulb Target Structures

The olfactory cortex encompasses several anatomically distinct regions each hypothesized to provide differential representation and processing of specific odors. Studies exploring whether or not the diversity of olfactory bulb input to olfactory cortices has functional meaning, however, are lacking. Here we tested whether two anatomically major olfactory cortical structures, the olfactory tubercle (OT) and piriform cortex (PCX), differ in their neural representation and processing dynamics of a small set of diverse odors by performing in vivo extracellular recordings from the OT and PCX of anesthetized mice. We found a wealth of similarities between structures, including odor-evoked response magnitudes, breadth of odor tuning, and odor-evoked firing latencies. In contrast, only few differences between structures were found, including spontaneous activity rates and odor signal-to-noise ratios. These results suggest that despite major anatomical differences in innervation by olfactory bulb mitral/tufted cells, the basic features of odor representation and processing, at least within this limited odor set, are similar within the OT and PCX. We predict that the olfactory code follows a distributed processing stream in transmitting behaviorally and perceptually-relevant information from low-level stations

Cerebral cortex expression of Gli3 is required for normal development of the lateral olfactory tract

<div><p>Formation of the lateral olfactory tract (LOT) and innervation of the piriform cortex represent fundamental steps to allow the transmission of olfactory information to the cerebral cortex. Several transcription factors, including the zinc finger transcription factor Gli3, influence LOT formation by controlling the development of mitral cells from which LOT axons emanate and/or by specifying the environment through which these axons navigate. <i>Gli3</i> null and hypomorphic mutants display severe defects throughout the territory covered by the developing lateral olfactory tract, making it difficult to identify specific roles for <i>Gli3</i> in its development. Here, we used <i>Emx1Cre</i>;<i>Gli3</i>^<i>fl/fl</i> conditional mutants to investigate LOT formation and colonization of the olfactory cortex in embryos in which loss of <i>Gli3</i> function is restricted to the dorsal telencephalon. These mutants form an olfactory bulb like structure which does not protrude from the telencephalic surface. Nevertheless, mitral cells are formed and their axons enter the piriform cortex though the LOT is shifted medially. Mitral axons also innervate a larger target area consistent with an enlargement of the piriform cortex and form aberrant projections into the deeper layers of the piriform cortex. No obvious differences were found in the expression patterns of key guidance cues. However, we found that an expansion of the piriform cortex temporally coincides with the arrival of LOT axons, suggesting that <i>Gli3</i> affects LOT positioning and target area innervation through controlling the development of the piriform cortex.</p></div

Elucidating Poor Decision-Making in a Rat Gambling Task

Although poor decision-making is a hallmark of psychiatric conditions such as attention deficit/hyperactivity disorder, pathological gambling or substance abuse, a fraction of healthy individuals exhibit similar poor decision-making performances in everyday life and specific laboratory tasks such as the Iowa Gambling Task. These particular individuals may provide information on risk factors or common endophenotypes of these mental disorders. In a rodent version of the Iowa gambling task – the Rat Gambling Task (RGT), we identified a population of poor decision makers, and assessed how these rats scored for several behavioral traits relevant to executive disorders: risk taking, reward seeking, behavioral inflexibility, and several aspects of impulsivity. First, we found that poor decision-making could not be well predicted by single behavioral and cognitive characteristics when considered separately. By contrast, a combination of independent traits in the same individual, namely risk taking, reward seeking, behavioral inflexibility, as well as motor impulsivity, was highly predictive of poor decision-making. Second, using a reinforcement-learning model of the RGT, we confirmed that only the combination of extreme scores on these traits could induce maladaptive decision-making. Third, the model suggested that a combination of these behavioral traits results in an inaccurate representation of rewards and penalties and inefficient learning of the environment. Poor decision-making appears as a consequence of the over-valuation of high-reward-high-risk options in the task. Such a specific psychological profile could greatly impair clinically healthy individuals in decision-making tasks and may predispose to mental disorders with similar symptoms

Le systeme cholinergique afferent au bulbe olfactif : etude anatomo-fonctionnelle chez le rat

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Passages de vie... passages de cerveau

Nervous cells have anatomic features which give them great communication capacities. After a brief overview of these functional units, we shall see they are at the heart of the paths that criss-cross our brains. Far from being a box of rigid connections, that network of cerebral communications is perpetually reorganised in relation to our environment. That brain plasticity is particularly solicited in the process that leads to the construction of the memory circuits, to the storage of our memories and their remembrance.Les cellules nerveuses possèdent des particularités anatomiques qui leur confèrent de grandes capacités de communication. Après un bref survol de ces unités fonctionnelles, nous verrons qu'elles sont à la base des chemins qui sillonnent notre cerveau. Loin d'être une boîte de connexions rigides, ce réseau de communications cérébrales est en perpétuel remaniement, en interaction avec notre environnement. Cette plasticité cérébrale est particulièrement sollicitée dans les processus qui conduisent à la construction des circuits de la mémoire, au stockage de nos souvenirs et à leur rappel.Ravel Nadine. Passages de vie... passages de cerveau. In: Les Cahiers du Musée des Confluences. Revue thématique Sciences et Sociétés du Musée des Confluences, tome 6, 2010. Passages. pp. 65-74

P5.60 Encoding vs retrieval of episodic memory in rats: different theta oscillatory signatures in hippocampo-cortical networks according to individual episodic memory profile

International audienceA: Posterior piriform cortex raw signal Aquisition through a wireless neural headstage system (TBSI) (sampling rate of 15KHz, bandpass filter 0,8-7000 Hz) B: Time frequency map of corresponding signal Morlet Wavelet Transform and wavelet ridge extraction C: Signal filtered in the 15-40 Hz frequency band and calculated envelope 2,5ms at 0,4 Khz sampling rate D: Behavioral markers Odor is triggered for 10 seconds by the rat nosepoke 3 seconds after the nosepoke, the pipette becomes accessible and the rat has to make a choice (either licking or avoiding) E: Time course of the trial Changes in power envelope are extracted on five 500msperiods (from PRE to POST6) and normalized (ratio) by the same signal extracted on a reference period (REF:-1500 to-1000 ms before the nosepoke

P5.60 Encoding vs retrieval of episodic memory in rats: different theta oscillatory signatures in hippocampo-cortical networks according to individual episodic memory profile

International audienceA: Posterior piriform cortex raw signal Aquisition through a wireless neural headstage system (TBSI) (sampling rate of 15KHz, bandpass filter 0,8-7000 Hz) B: Time frequency map of corresponding signal Morlet Wavelet Transform and wavelet ridge extraction C: Signal filtered in the 15-40 Hz frequency band and calculated envelope 2,5ms at 0,4 Khz sampling rate D: Behavioral markers Odor is triggered for 10 seconds by the rat nosepoke 3 seconds after the nosepoke, the pipette becomes accessible and the rat has to make a choice (either licking or avoiding) E: Time course of the trial Changes in power envelope are extracted on five 500msperiods (from PRE to POST6) and normalized (ratio) by the same signal extracted on a reference period (REF:-1500 to-1000 ms before the nosepoke

P5.60 Encoding vs retrieval of episodic memory in rats: different theta oscillatory signatures in hippocampo-cortical networks according to individual episodic memory profile

International audienceA: Posterior piriform cortex raw signal Aquisition through a wireless neural headstage system (TBSI) (sampling rate of 15KHz, bandpass filter 0,8-7000 Hz) B: Time frequency map of corresponding signal Morlet Wavelet Transform and wavelet ridge extraction C: Signal filtered in the 15-40 Hz frequency band and calculated envelope 2,5ms at 0,4 Khz sampling rate D: Behavioral markers Odor is triggered for 10 seconds by the rat nosepoke 3 seconds after the nosepoke, the pipette becomes accessible and the rat has to make a choice (either licking or avoiding) E: Time course of the trial Changes in power envelope are extracted on five 500msperiods (from PRE to POST6) and normalized (ratio) by the same signal extracted on a reference period (REF:-1500 to-1000 ms before the nosepoke