Taste and smell are intertwined in the rat brain

A recent paper in Current Biology titled “A Multisensory Network for Olfactory Processing” from the Katz Lab in Psychology tackles the question of where in rat brain the senses of taste and smell are processed, and just how distinct the two senses are. In addition to Katz, authors on the paper include former postdoctoral fellows Joost Maier and Jennifer Li, as well as Neuroscience graduate student Meredith Blankenship.

The paper discusses their finding that the tongue and the nose work together to help you decide what potential foods are actually good to eat. This intimate cooperation leads to an intertwining and interdependence of function; everyone who has had a cold knows that things don’t taste right when the sense of smell is blocked (by snot). They now show that the opposite is true as well–specifically, that the part of the cortex known to be responsible for taste is also required for the sense of smell.

Recordings from taste and olfactory cortex

First, they show that there is a strong neural connection between taste cortex (GC) and olfactory cortex (PC): this connection ensures that information about tastes in the mouth reaches the latter from the former, but also ensures that a constant chatter of action potentials (the language of the brain) flows between the two, even in the total absence of a substance on the tongue. Thus, switching those taste cortex neurons off both removes any evidence of taste information in olfactory cortex AND changes the way olfactory cortex deals with odor information arriving directly from the nose. The result of this impact is striking: a rat utterly fails to recognize a familiar odor when taste cortex is silent; the taste system is a part of the smell system.

The implications of this finding for neuroscience are far-reaching. It suggests a major breakdown of the basic dogma that the different sensory systems, each of which originate in distinct sense organs (the nose for smell, the tongue for taste) process their input independently. In fact, the brain likely doesn’t “see” tastes and smells as separate at all, but as unified parts of holistic objects…FOOD.

Maier JX, Blankenship ML, Li JX, Katz DB. A Multisensory Network for Olfactory Processing. Curr Biol. 2015.

7 Division of Science Faculty Recently Promoted

Congratulations to the following 7 Division of Science faculty members were recently promoted:

katz_dbDonald B. Katz (Psychology) has been promoted to Professor of Psychology. Don came to Brandeis as an Assistant Professor with a joint appointment in the Volen Center for Complex Systems in 2002 and was promoted to Associate Professor and awarded tenure in 2008. Don’s teaching and research serve central roles in both Psychology and the Neuroscience program. His systems approach to investigating gustation blends behavioral testing of awake rodents with multi-neuronal recording and pharmacological, optogenetic, and modelling techniques. Broad themes of the neural dynamics of perceptual coding, learning, social learning, decision making, and insight run through his work on gustation. For his research, Don has won the 2007 Polak Award and the 2004 Ajinomoto Young Investigator in Gustation Award, both from the Association for Chemoreception Sciences. Don has taught “Introduction to Behavioral Neuroscience” (NPSY11b), “Advanced Topics in Behavioral Neuroscience” (NPSY197a), “Neuroscience Proseminar” (NBIO250a), “Proseminar in Brain, Body, and Behavior II” (PSYC302a), “How Do We Know What We Know?” (SYS1c). For his excellence in teaching, Don has been recognized with the 2013 Jeanette Lerman-Neubauer ’69 and Joseph Neubauer Prize for Excellence in Teaching and Mentoring, the 2006 Brandeis Student Union Teaching Award, and the 2006 Michael L. Walzer Award for Teaching and Scholarship.

Nicolas RohlederNicolas Rohleder (Psychology) has been promoted to Associate Professor in Psychology. Nic is a member of the Volen Center for Complex Systems and on the faculty of the Neuroscience and Health, Science, Society and Policy programs. His course offerings include “Health Psychology” (PSYC38a), “Stress, Physiology and Health” (NPSY141a), and” Research Methods and Laboratory in Psychology” (PSYC52a). Nic’s research investigates how acute and chronic or repeated stress experiences affect human health across individuals and age groups. His laboratory performs studies with human participants using methods than span behavioral to molecular to understand how the hypothalamus-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) regulate peripheral immunological responses and how these processes mediate cardiovascular disease, type 2 diabetes, and cancer, and aging. His research and teaching fill unique niches for all his Brandeis departmental and program affiliations. Nic’s research excellence has been recognized outside Brandeis with awards including the 2013 Herbert Weiner Early Career Award of the American Psychosomatic Society and the 2011 Curt P. Richter Award of the International Society of Psychoneuroendocrinology.

Matthew HeadrickMatthew Headrick (Physics) has been promoted to Associate Professor of Physics. He works at the intersection of three areas of modern theoretical physics: quantum field theory, general relativity, and quantum information theory. In particular, he uses information-theoretic techniques to study the structure of entanglement — a fundamental and ubiquitous property of quantum systems — in various kinds of field theories. Much of his work is devoted to the study of so-called “holographic” field theories, which are equivalent, in a subtle and still mysterious way, to theories of gravity in higher-dimensional spacetimes. Holographic theories have revealed a deep connection between entanglement and spacetime geometry, and Headrick has made significant contributions to the elucidation of this connection. Understanding the role of entanglement in holographic theories, and in quantum gravity more generally, may eventually lead to an understanding of the microscopic origin of space and time themselves.

Isaac Krauss

Isaac Krauss (Chemistry) has been promoted to Associate Professor of Chemistry. He is an organic chemist and chemical biologist whose research is at the interface of carbohydrate chemistry and biology. His lab has devised tools for directed evolution of modified DNA and peptides as an approach to designing carbohydrate vaccines against HIV. Krauss is also a very popular teacher and the recipient of the 2015 Walzer prize in teaching for tenure-track faculty.

Xiaodong Liu (Psychology) has been promoted to Associate Professor in Psychology. Xiaodong provides statistical training for graduate students in Psychology, Heller School, IBS, Neuroscience, Biology, and Computer Science, he serves as a statistical consultant for Xiaodong LiuPsychology faculty and student projects, and he performs research on general & generalized linear modeling and longitudinal data analysis, which he applies to child development, including psychological adjustment and school performance. He teaches “Advanced Psychological Statistics I and II” (PSYC210a,b), “SAS Applications” (PSYC140a), “Multivariate Statistics I: Applied Structural Equation Modeling” (PSYC215a), and “Multivariate Statistics II: Applied Hierarchical Linear Models” (PSYC216a). He is developing a new course on “The R Statistical Package and Applied Bayes Analysis”, and he recently won a Provost’s Innovations in Teaching Grant for “Incorporating Project-based modules in Learning and Teaching of Applied Statistics”.

Gabriella SciollaGabriella Sciolla (Physics) has been promoted to Professor of Physics. She is a particle physicist working on the ATLAS experiment at CERN in Geneva, Switzerland. Sciolla and her group study the properties of the newly discovered Higgs Boson and search for Dark Matter particles produced in high-energy proton-proton collisions at the Large Hadron Collider. Sciolla is also responsible for the reconstruction and calibration of the muons produced in ATLAS. These particles are key to both Higgs studies and searches for New Physics.

Nianwen Xue (Computer Science) has been promoted to Associate Professor of Computer Science.  The Computer Science Department is pleased to annNianwen Xueounce the promotion of Nianwen (Bert) Xue to Associate Professor with tenure. Since joining Computer Science he has made significant contributions to the research and teaching efforts in Computational Linguistics, including growing a masters program from zero up to 18 students this year. His publications are very well regarded, and focus on the development and use of large corpora for natural language processing, especially in Chinese. He has built a sizable lab with diverse funding that students from around the world are vying to enter.

Thank you to the following department chairs for their contributions to this post:

  • Paul DiZio, Psychology
  • Jane Kondev, Physics
  • Jordan Pollack, Computer Science
  • Barry Snider, Chemistry

How does the brain decide whether you like what you eat?

When we encounter a taste, we appreciate both its chemosensory properties and its palatability—the degree to which the taste is pleasurable or aversive. Recent work suggests that the processing of this complex taste experience may involve coordination between multiple brain areas. Dissecting these interactions help understand the organization and working of the taste system.

F4.largeThe lateral hypothalamus (LH) is a region of the brain important for feeding. In a rodent, damage the LH, and the rodent may starve itself to death; stimulate it, and you get a curious mix of voracious eating and expressions of disgust over what is being eaten. Such data suggest that LH plays a complex game of balancing escape and avoidance, palatability and aversion, during the evaluation of a taste stimulus. Little is known, however, about how neurons in LH actually respond to tastes of different valences.

Brandeis postdocs Jennifer Li and Takashi Yoshida. undergraduate Kevin Monk ’13, and Associate Professor of Psychology Don Katz have recently published a study of neuronal reponses in LH in the Journal of Neuroscience. They have shown that taste-responsive neurons in LH break neatly down into two groups–one that responds preferentially to palatable tastes and one to aversive tastes. Virtually every taste neuron in LH could be identified as a palatable- or aversive-preferring neuron. In addition, even without considering the specific tastes to which a particular neuron responded, these two groups of neurons could be differentiated according to their baseline firing rate, shape of response, and tuning width. While these neurons were spatially intermingled, several pieces of data (functional connectivity analysis, relationship to responses in amygdala and cortex) suggest that they are parts of distinct neural circuits. These results offer insights into the multiple feeding-related processes that LH manages, and how the hypothalamus’ role in these processes might be related to its connection to other parts of the taste system.

Li JX, Yoshida T, Monk KJ, Katz DB. Lateral Hypothalamus Contains Two Types of Palatability-Related Taste Responses with Distinct Dynamics. J Neurosci. 2013;33(22):9462-73.

Taste affects your sense of smell in the olfactory cortex

Professor Don Katz’s lab is interested in learning and behavior related to the gustatory system (the sense of taste). In a new paper in Journal of Neuroscience, also covered by the Washington Post website, Katz and  postdoc Joost Maier together with Univ. of Utah professor Matt Wachowiak, studied how tastes affect the processing of odors.

When any animal eats, it both smells and tastes the food, and has to make a split-second decision — is it nutritious or poisonous? Do I swallow it or spit it out? Accordingly, there has to be a processing system in the brain to integrate the information and make rapid decisions. It has been known for some time that odors affect the processing of taste in gustatory cortex. In the new article, the researchers demonstrate the effects of taste inputs on olfactory cortex. According to Maier, “this means is that the different senses are really interacting with each other at a much earlier level than previously thought,”.

Dynamic Coding in Neural Signals Workshop on July 29

The Center of Excellence for Learning in Education, Science and Technology (CELEST) is holding a workshop on its cross-function initiative Dynamic Coding in Neural Signals at Boston University (677 Beacon Street, Room B02) on July 29, 2011. from 1:00 – 5:45 pm. The workshop is free and open to the public. There will be talks by invited speakers from 1 – 4:15, including presentations by Don Katz (“Perceptual processing via coherent sequences of ensemble states”) and Paul Miller (“Stochastic transitions between discrete states in models of taste processing and decision-making”). a student and postdoc poster session will follow, with ample opportunity for discussion between presenters and workshop attendees.

CELEST is a joint venture of scientists at four Boston-area universities including Brandeis and is sponspored by the National Science Foundation. Robert Sekuler, Louis and Frances Salvage Professor of Psychology at Brandeis, is a co-Principal Investigator, and Biology and Neuroscience faculty Gina Turrigiano and Paul Miller are also involved in the center.

Hey – Fred ate that and lived to tell the tale

Don Katz discusses the interactions between taste, smell, and learning in a new story on BrandeisNOW.

“Rats learn what food that they like from smelling the breath of other rats,” says Katz, an associate professor of psychology and neuroscience. “A rat will essentially say, ‘Hey – Fred ate that and lived to tell the tale’ so later, when that rat is offered a choice, he will gravitate toward the food that he smelled on the other rat’s breath.”

How to tell what a rat likes: look at his face.

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