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.

Six scientists secure fellowships

One current undergraduate, and five alumni, from the Brandeis Sciences were honored with offers of National Science Foundation Graduate Research Fellowships in 2012. The fellowships, which are awarded based on a national competition, provide three full years of support for Ph.D. research and are highly valued by students and institutions. These students are:

  • Samuel McCandlish ’12 (Physics) , a current student who did research with Michael Hagan and Aparna Baskaran, resulting in a paper “Spontaneous segregation of self-propelled particles with different motilities” in Soft Matter (as a junior). He then switched to work with Albion Lawrence for his senior thesis research. Sam will speak about “Bending and Breaking Time Contours: a World Line Approach to Quantum Field Theory” at the Berko Symposium on May 14.  Sam has been offered a couple of other fellowships as well, so he’ll have a nice choice to make. Sam will be heading to Stanford in the fall to continue his studies in theoretical physics.
  • Briana Abrahms ’08 (Physics). After graduating from Brandeis, Briana followed her interests in ecological and conversation issues, and  in Africa as a research assistant with the Botswana Predator Conservation Trust, Briana previously described some of her experiences here in “Three Leopards and a Shower“. Briana plans to pursue as Ph.D. in Ecology at UC Davis.
  • Sarah Robinson ’07 (Chemistry). Sarah did undergraduate research with Irving Epstein on “Pattern formation in a coupled layer reaction-diffusion system”. After graduating, Sarah spent time with the Peace Corps in Tanzania, returning to study Neurosciene at UCSF.
  • Si Hui Pan ’10 (Physics) participated in a summer REU program at Harvard, and continued doing her honors thesis in collaboration with the labs at Harvard. Her award is to study condensed matter physics at MIT.
  • Elizabeth Setren ’10 was a Mathematics and Economics double major who worked together with Donald Shepard (Heller School) on the cost of hunger in the US. She has worked as an Assistant Economist at the Federal Reserve Bank of New York and her award is to study Economics at Harvard.
  • Michael Ari Cohen ’01 (Psychology) worked as a technology specialist for several years before returning to academia as  PhD student in the Energy and Resources Group at UC Berkeley.

Congratulations to all the winners!

Older Adults are Better at Spotting Fake Smiles

Studies of aging and the ability to recognize others’ emotional states tend to show that older adults are worse than younger adults at recognizing facial expressions of emotion, a pattern that parallels findings on non-social types of perception. Most of the previous research focused on the recognition of negative emotions such as anger and fear. In a study “Recognition of Posed and Spontaneous Dynamic Smiles in Young and Older Adults” recently published in Psychology and Aging, Derek Isaacowitz’s Emotion Laboratory set out to investigate possible aging effects in recognizing positive emotions; specifically, the ability to discriminate between posed or “fake” smiles and genuine smiles. They video-recorded different types of smiles (posed and genuine) from younger adults (mean age = 22) and older adults (mean age = 70). Then we showed those smiles to participants who judged whether the smiles were posed or genuine.

Across two studies, older adults were actually better at discriminating between posed and genuine smiles compared to younger adults. This is one of the only findings in the social perception literature suggesting an age difference favoring older individuals. One plausible reason why older adults may be better at distinguishing posed and spontaneous smiles is due to their greater experience in making these nuanced social judgments across the life span; this may then be a case where life experience can offset the effects of negative age-related change in cognition and perception.

This was the first known study to present younger and older adult videotaped smiles to both younger and older adult participants; using dynamic stimuli provides a more ecologically valid method of assessing social perception than using static pictures of faces. The findings are exciting because they suggest that while older adults may lose some ability to recognize the negative emotions of others, their ability to discriminate posed and genuine positive emotions may remain intact, or even improve.

The Emotion Laboratory is located in the Volen Center at Brandeis. First author Dr. Nora Murphy (now Assistant Professor of Psychology at Loyola Marymount University) conducted the research as a postdoctoral research fellow, under the supervision of Dr. Isaacowitz, and second author Jonathan Lehrfeld (Brandeis class of 2008) completed his Psychology senior honors thesis as part of the project. The research was funded by the National Institute of Aging.

Protected by Akismet
Blog with WordPress

Welcome Guest | Login (Brandeis Members Only)