10 janvier 2017 (DEC-Ling)

Marie Coppola (University of Connecticut)
Sign language and language emergence

21 février 2017 (LNC)

Emeran Mayer (UCLA)
The emerging science of brain gut microbiome communication

Résumé :

Preclinical studies published during the past decade have clearly established an important role of the gut microbiota in behavior and in the modulation of key components of the gut brain axis, including brain structure and function. However, there is limited evidence from studies in human subjects to demonstrate a causative role of gut microbiota brain interactions in health and disease. Our group has published the first evidence that perturbation of the gut microbiome in healthy individuals can lead to altered brain responses to emotional stimuli. This effect was likely mediated by alterations in gut microbial metabolites, as no effect of the probiotic intervention on gut microbial composition was observed. A number of clinical studies have identified associations of altered gut microbial composition with clinical symptoms of patients with major depressive disorder, Parkinson’s disease, hepatic encephalopathy, and autism spectrum disorders. Fecal microbial transfer from some of these patients alters emotional behavior in rodents. Associations of gut microbial composition and metabolites with brain parameters have also been shown in patients with irritable bowel syndrome and in healthy subjects. We have been using multimodal brain imaging of healthy human subjects and disease populations (irritable bowel syndrome, obesity) to identify correlations between a multitude of structural and functional brain parameters with gut microbial composition and microbial metabolites. Early results demonstrate cross sectional correlations between gut microbial composition and grey and white matter changes primarily within sensory processing regions of the brain. In ongoing studies, we are looking at the involvement of gut microbiota and their metabolites in brain changes in mediating the therapeutic effects of bariatric surgery in obesity, and of mind based therapies (cognitive behavioral therapy, mindfulness based stress reduction) in chronic visceral pain

A propos d'Emeran Mayer :
Emeran A Mayer is a Gastroenterologist, Neuroscientist and Professor in the Departments of Medicine, Physiology and Psychiatry at the David Geffen School of Medicine at UCLA. He is the Executive Director of the G. Oppenheimer Center for Neurobiology of Stress and Resilience at UCLA, and co-director of the CURE: Digestive Diseases Research Center. As one of the pioneers and leading researchers in the role of mind-brain-body interactions in health and chronic disease, his scientific contributions to U.S. national and international communities in the broad area of basic and translational enteric neurobiology with wide-ranging applications in clinical GI diseases and disorders is unparalleled. He has published more than 300 scientific papers, and co edited 3 books. He is the recipient of the 2016 David McLean award from the American Psychosomatic Society. His most recent work has focused on the dialogue between the gut microbiota and the brain, the role of food addiction in obesity, and the role of the brain in chronic inflammatory diseases of the gut.

Mayer has a longstanding interest in ancient healing traditions and affords them a level of respect rarely found in Western Medicine. He has been involved in documentary film productions about the Yanomami people in the Orinoco region of Venezuela, and the Asmat people in Irian Jaya, and has recently co produced the award winning documentary “In Search of Balance”.

Dr. Mayer has been interviewed on National Public Radio, PBS and by many national and international media outlets including the Los AngelesTimes, Atlantic magazine and Stern and Spiegel Online. He has spoken at UCLA TEDx on the Mysterious Origins of Gut Feelings in 2015, and his book The Mind Gut Connection was published by Harper&Collins in July of 2016 and has been translated into 10 languages.

21 mars 2017 (IJN)

Peter Carruthers (University of Maryland)
The conscious mind as marionette

Résumé :

We tend to think that our conscious minds that are in control, much of the time; or at any rate, that our conscious minds are capable of taking control. When we pause to reflect, and act on our reflections, it is our conscious thoughts -- our conscious beliefs, goals, and decisions -- that get to control what we do. Or so we think. But this sense of self-control is an illusion. In reality our conscious minds are controlled and manipulated by unconscious processes. We decide what to pay attention to, what to remember, what to think of, what to imagine, and what sentences to rehearse in inner speech, thereby determining the conscious contents of working memory. There is control, of course, and it is a form of self-control. But is not control by a conscious self. Rather, what we take to be the conscious self is a puppet manipulated by our unconscious goals, beliefs, and decisions. This account is supported by a raft of evidence from across cognitive science.

25 avril 2017 (LNC)

Thomas Preat
Memory dynamics and energy metabolism in drosophila

Résumé :

The drosophila brain of is an exciting biological object: although it consists of a small number of neurons (about 100,000), it is highly structured and controls sophisticated behavior. Interestingly, the brain of drosophila works with the same basic components as that of mammals (neurotransmitters, receptors, signal transduction cascades, transcription factors...), and most of the molecular mechanisms underlying memory processes were preserved during evolution. Our team investigates the mechanisms of olfactory learning and memory, and we are especially interested in the mechanisms involved in the formation of long-term memory. Efficient energy use has constrained the evolution of nervous systems. However, it is unresolved whether energy metabolism may resultantly regulate major brain functions. Our observation that drosophila flies double their sucrose intake at an early stage of long-term memory formation initiated the investigation of how energy metabolism intervenes in this process. Cellular-resolution imaging of energy metabolism reveals a concurrent elevation of energy consumption in neurons of the mushroom body, the fly’s major memory center. Strikingly, upregulation of mushroom body energy flux is both necessary and sufficient to drive long-term memory formation. This effect is triggered by a specific pair of dopaminergic neurons afferent to the mushroom bodies. Hence, dopamine signaling mediates an energy switch in the mushroom body that controls long-term memory encoding. Our data thus point to an instructional role for energy flux in the execution of demanding higher brain functions.

23 mai 2017 (LSCP)

Daniel Margoliash (University of Chicago)
"New concepts in motor control and sensorimotor learning: lessons from birdsong"

Résumé :
Birdsong is a classic model in neuroethology, and continues to provide valuable insights into organization of brain and complex learned behavior. Here we address two central issues: the organization of the motor system for song production, and the realtime representation of feedback. A popular model in birdsong reflects a top-down command-control view, the standard for motor control. Instead, we show that activity in the “HVC” premotor cortical structure has information of the fine-grained dynamics of vocal movements, including near-zero delay relative to muscle movements. These results can be explained by interactions between top down and bottom up influences on motor control, analyzed from the perspective of nonlinear dynamics. To understand how changes in singing behavior are represented in realtime, we turned to an unlikely preparation, HVC whole cell slice recordings. We show that the intrinsic somatic neuronal properties of a class of HVC neurons show unanticipated homogeneity within individual birds and variation between individuals. The distribution of intrinsic properties are regulated during song development, are modified in adults by changes in singing that are driven by abnormal auditory feedback, and in adults these changes occur rapidly, at most taking hours and perhaps only seconds. These data provide compelling evidence that intrinsic somatic electrophysiological properties contribute to behavioral plasticity in a fashion previously conceptualized only for synapses. Collectively, these results have broad implications for neural coding.