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Encoding taste and place in the hippocampus

February 20, 2019 By

The ambience of a good meal can sometimes be as memorable as the taste of the food itself. A new study from Shantanu Jadhav and Donald Katz’s labs, published in the February 18 edition of The Journal of Neuroscience, may help explain why. This research identified a subset of neurons in the hippocampus of rats that respond to both places and tastes.

The hippocampus is a brain region that has long been implicated in learning and memory, especially in the spatial domain. Neurons in this area called “place cells” respond to specific locations as animals explore their environments. The hippocampus is also connected to the taste system and active during taste learning. However, little is known about taste processing in the hippocampus. Can place cells help demarcate the locations of food?

To test this hypothesis, Neuroscience PhD student Linnea Herzog, together with staff member Leila May Pascual and Brandeis undergraduates Seneca Scott and Elon Mathieson, recorded from neurons in the hippocampus of rats as the rats explored a chamber. At the same time, different tastes were delivered directly onto the rats’ tongues.

Analyzing how place cells responded to tastes delivered inside or outside of their place field

The researchers found that about 20% of hippocampal neurons responded to tastes, and could discriminate between tastes based on palatability. Of these taste-responsive neurons, place cells only responded to tastes that were consumed within that cell’s preferred location. These results suggest that taste responses are overlaid onto existing mental maps. These place- and taste-responsive cells form a cognitive “taste map” that may help animals remember the locations of food.

Read more:  So close, rats can almost taste it

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Taste and smell are intertwined in the rat brain

October 7, 2015 By

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.

Filed Under: labs, Neuroscience, Psychology Tagged With: , , , ,

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

May 31, 2013 By

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.

Filed Under: labs, Neuroscience, postdocs, Psychology, Undergrads Tagged With: , , , , ,

Taste affects your sense of smell in the olfactory cortex

December 6, 2012 By

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,”.

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Hey – Fred ate that and lived to tell the tale

July 7, 2011 By

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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A Taste of Don

October 25, 2010 By

Even when we are trying to take a break from lab and chemosensory research on the weekends, it somehow ends up right in our laps. Riding the T we found in one of the ubiquitous discarded papers this article about the science of taste that highlights our own Don Katz, doing his part to mix business and pleasure this week at one of Boston’s premier cocktail destinations:

http://digboston.com/taste/2010/10/science-of-taste/

– Yaihara Fortis and Benjamin Rubin


(editor’s note: the fundraiser is on Wed, Oct 27, see http://lupecboston.com/2010/10/14/science-of-taste-seminar/)

Filed Under: Neuroscience, Psychology Tagged With: , , , ,

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