How Does Our Brain Assign Value to Food?

Fig. 1: Schematic representation of how our brain incorporates perception of food items into willingness to pay [ref 3].How do we decide what and how much to eat and how much we are willing to pay for food? We may think about these questions sometimes, but apparently, our brains actually “compute” food values when we make decisions about what to eat. These value signals have been found to possess regional specificity and recent research demonstrates that sub-regions within the orbitofrontal cortex (OFC), play unique roles [1]. The OFC is involved in higher-order cognitive functions such as decision-making and human brain imaging studies have begun to illustrate functional contributions of the OFC in food value computation. For example, several studies have indicated that the medial OFC encodes generalized value signals, independent of direct experience or consideration of future rewards, while the lateral OFC encodes specific value [2].

Recent work has elucidated the “constituent attributes” that underlie the construction of food value and how they are both represented and integrated in the OFC [1]. By using a food-based decision task in human participants, researchers found that a subjective sense of nutrients are important in assigning value to food; nutritive aspects of our food, such as protein, fat, carbohydrates and vitamins, appear to be important predictors of the subjective value of food. Multi-voxel pattern analyses (MVPA) of functional magnetic resonance imaging (fMRI) data revealed that both the medial and lateral OFC represent food value signals with the lateral OFC encoding for the basic nutritional aspects of food. The results of effective connectivity analyses between OFC sub-regions indicated that information in relation to subjective nutrient factors from the lateral OFC are then integrated at the time of valuation within the medial OFC, which “computes” overall values. More simply, the lateral OFC estimates the amount of nutrients and the medial OFC works out a weighted sum value, influencing behavior.

Understanding how a subjective value signal is generated in the lateral OFC and how inter-regional signals relate to more involved network representations remains elusive, yet these studies provide new data for further study with important implications for understanding neural and psychological mechanisms underlying food-valuation processes, salient for diseases in which these processes are out of balance, such as in eating disorders [1]. Further, these studies represent a conceptual advance which may eventually be generalized to other value judgments [3].




1. Suzuki, S.; Cross, L.; O’Doherty, J. P., Elucidating the underlying components of food valuation in the human orbitofrontal cortex. Nat. Neurosci. 2017, 20 (12), 1780-1786.

2. (a) Barron, H. C.; Dolan, R. J.; Behrens, T. E. J., Online evaluation of novel choices by simultaneous representation of multiple memories. Nat. Neurosci. 2013, 16 (10), 1492-1498 ; (b) Howard, J. D.; Gottfried, J. A.; Tobler, P. N.; Kahnt, T., Identity-specific coding of future rewards in the human orbitofrontal cortex. Proceedings of the National Academy of Sciences of the United States of America 2015, 112 (16), 5195-5200.

3. Pessiglione, M.; Wiehler, A., Breaking down a meal. Nat. Neurosci. 2017, 20 (12), 1659-1660.


Exciting modification of CRISPR/Cas9 gene editing system leads to disease fighting gene activation

The CRISPR/Cas 9 gene editing technology has undergone ‘second generation’ advancement attempts towards the induction of gene activation, however these efforts have frequently been plagued by technical limitations for in vivo applications [1].  Researchers from the Belmonte lab at the Salk Institute have now successfully added a transcriptional activation domain [1,2,3].  This modification eschews the traditional editing system’s double strand breaks, which are cause for concern as breaks may lead to mutations, which in turn limit their potential use for human disease. The new approach effectively confers epigenetic changes in gene expression, as the DNA sequence remains unaltered – opening a pathway for eventual use in humans. 

The team tested individual packaging combinations of the discrete molecular components used in the conventional editing system, with some modifications, into the adenovirus vehicle required for delivery [1,2,3]. The fusion of CAS9 with the activator previously presented problems, as the resulting protein was too large for delivery into the vehicle. In this new work, the vehicle was separately packaged with either CAS9, or a ‘dead’ version CAS9 lacking nuclease activity, or with the guide RNAs required for genomic targeting along with molecular activation switches; the appropriate combination induced the activation of target genes. In very exciting functional experiments that followed, the group tested their system in mice and observed activation of genes involved in kidney disease, type 1 diabetes and muscular dystrophy. The reported results demonstrated physiological improvements. The team is working to improve this system and to increase the number of diseases they can target with their sights set on ultimately testing for safe use in humans.     




References and Sources

[1]H-K Liao, F Hatanaka, T Araoka, P Reddy, M-Z Wu, Yi Sui, T Yamauchi, M Sakurai, DD O’Keefe, E Núñez-Delicado, P Guillen, JM Campistol, C-J Wu, L-F Lu, CR Esteban, JCI Belmonte. In Vivo Target Gene Activation via CRISPR/Cas9-Mediated Trans -epigenetic Modulation. Cell, 2017; DOI: 10.1016/j.cell.2017.10.025

[2]Cell Press. (2017, December 7). CRISPR-Cas9 technique targeting epigenetics reverses disease in mice. ScienceDaily. Retrieved December 12, 2017 from



Graphical abstract from [1], illustrating target gene activation in mice.


Vertical limits of bat echolocation

Contrary to popular belief, bats are not actually blind—this misconception stems from the fact that more than half of the 900 species do rely upon echolocation to navigate during their nocturnal activities. Echolocation, the use of sonar (sound navigation and ranging) with special morphological and physiological adaptations, enables bats to “see” with sound! Bats emit high-frequency calls and listen for the returning echoes, which provide them with the information they need to negotiate complex terrain and track moving prey in the dark. This echolocation is so precise they can discriminate differences of less than one millimeter in surface textures [1]!

I was surprised to learn that this impressive capability has a big flaw. In a recently published paper [2], scientists found that bat echolocation has a tough time with some environmental features. Specifically, smooth, vertical surfaces (think metal or glass plates on a building) provide a false environmental cue to the bat, tricking the animal into sensing that it is actually flying into open air! As you can imagine, this does not end well for the bats. Sadly, bats are often found dead or injured near buildings and other smooth structures, and the false cues the bats pick up from the buildings may be a major culprit. 

The sensory trap that a smooth building may create is not the only one that bats can fall prey to. In fact, Dr. Stefan Grief demonstrated in a previous study [3] that smooth metal or plastic plates also act as a sensory trap when laid on the ground; bats mistook these surfaces for water. In his recent study [3] at the Max Planck Institute for Ornithology, Dr. Grief and his colleagues flew greater mouse-eared bats around a dark, rectangular flight tunnel. Near one of the tunnel’s corners, the researches placed a metal plate either on the ground or against the wall. The result? All but two of the bats out of 21 hit the vertical plate at least once, but none of the bats ever hit the horizontal plate of any other part of the tunnel.

However, as noted previously, bats are not blind and they do integrate echolocation and vision to navigate. Why then do smooth, vertical structures pose such a navigational hazard to bats? That is still a question pondered by bat biologists, and one that Dr. Greif aims to explore in the future.


  1. Simmons, J. A., Ferragamo, M. J., & Moss, C. F. (1998). Echo-delay resolution in sonar images of the big brown bat, Eptesicus fuscusProceedings of the National Academy of Sciences of the United States of America95(21), 12647–12652.
  2. Greif, S., Zsebok, S., Schmieder, D., & Siemers, BM. (2017). Acoustic mirrors as sensory traps for bats. Science, 357(6355), 1045-1047.
  3. Greif, S., & Siemers, B. M. (2010). Innate recognition of water bodies in echolocating bats. Nature Communications1, 107–.





Making insulin at Eli LillyWho am I to disagree? – Well I like sweet things but being a type I diabetic for 20 years, I remember times when technology wasn’t quite where it is today. March 5, 1997, southern Germany, a little kid drinks roughly 20 bottles of soda and feels dizzy at night. That was the day I was diagnosed with type I diabetes. I went to the hospital and was put on the top notch therapy available at the time. To test my blood sugar, I had to squeeze a huge drop of blood onto a little strip. After a minute, I wiped it down, checked the color indicating a rough estimate how my blood sugar was doing, and then inserted the strip into a little machine that would count down from 120, one count per second, to zero, when I would then learn that my sugar was out of range, or roughly 7-8 times the amount a healthy person has in their blood. I got insulin – the fancy kind that the founders of Genentech (a big pharma company!) developed in E.coli and made some of their riches with- not the old fashioned insulin that was isolated from pigs’ pancreases at the slaughterhouse. You know, it was way better than just staying alive, I would have a normal life, so I was told. That being said, my mum got up every night to check my blood sugar at midnight, 3 am, 6 am and then throughout the day of course. I had to inject two different insulins with syringes – one every time I ate, the other one every 4-6 hours. Yet it seemed so much better than the stories I heard from other people about not knowing their sugar levels most of the time, except the one time a week you got to see the doctor who had a meter. It also seemed better than the life of the child I was in a room with, who had 3 hours of dialysis every day because he had no working kidneys. And it was of course all free, because Germany has a working healthcare system.

I traveled the world and the seven seas… Fast forward 20 years to 2017. I live in the US and diabetes care has undergone quite a revolution. I test my blood sugar now with a barely visible drop of blood and get a result within five seconds – no wiping, no color codes. The meter directly sends the results to my insulin pump, which I carry 24/7. I only use one type of insulin, which basically works instantaneously, and I don’t need to worry about injecting it regularly because the pump is programmed to do that. My pump does basically everything for me, it actually learns how my blood sugar reacts to things I eat and does all the insulin dosing for me. I just tell it what I’m eating and hope I make good estimates. I’m in a priority access program for this “artificial pancreas” and can’t quite believe how we far we have come to get to this point. It comes with a price tag (since we’re in the US, where we haven’t figured out health insurance yet) but it is closer to a “normal” life than I’ve ever had. It is an amazing feeling to look back at how treatment has progressed for a condition that killed people mercilessly until the middle of the last century and still does in many parts of the world.

Everybody’s looking for something. I’ve also been looking at news articles about how we’ll be able to cure diabetes entirely for about as long as I have had the condition. Of course, it’s always only preclinical work and some mouse was successfully injected with an insulin producing cell or something along those lines, and to me the whole topic goes right along the lines of the many talks on science ethics I’ve been to, where misrepresentation or over-representation of results to the general public is always a topic. I’ve been called by many excited aunts who read in the newspaper that I was going to be cured but, I still think I’ll see a cure in my lifetime.

Some of them want to use you. I’m also sure that Big Pharma won’t be too excited when a cure is found. Diabetes is essentially a dream of any pharma company. Your life depends on their product, and it keeps you alive and paying for a long time. I sometimes wonder if that is part of why we’re still excited about a pump that manages your diabetes for you. It is time to push forward… we have come a very long way for sure from where we were 20 years ago, but I’m also a lot more cynical about it now.

- MGS -

image source:


Sophia Spencer and #BugsR4Girls

In a story that has traveled across the globe, Sophia Spencer, an eight year old girl, who loves insects but was teased for it by her peers, has since been connected to myriad entomologists in large part due to her co-author, Morgan Jackson’s use of social media. Sophia – whose love for insects was inspired by a visit to a butterfly conservatory at the age of two - is now published in Annals of the Entomological Society of America. The publication, entitled, “Engaging for a Good Cause: Sophia's Story and Why #BugsR4Girls” [1] discusses Sophia’s experience of being mocked and teased in school for her love of bugs and her subsequent loss of engagement , which prompted her mother to reach out to the Entomological Society of Canada. Jackson, a social media volunteer at the Society, used twitter to rally support.  The piece evaluates the social media and wider media response following Jackson’s tweet, which garnered an outpouring of encouragement for this young scientist, and highlights the potential for social media to make positive impact across multiple platforms. The paper also delves into important topics such as stereotypes often imposed upon women in the workplace, as well as the underrepresentation of women in science.

More to the point, the wide-scale response brought back Sophia’s confidence and “old funny self”.  Sophia’s story is as heartwarming as it is important, and is especially poignant amidst our currently divisive political climate.  Public encouragement and support transformed the haunting spectre of bullying into a message of hope – and it is my hope that this story continues on and inspires children who might feel that they are judged or shunned because they might be different, because the truth is, we are all different! How much better to celebrate our differences! This story has many refreshing messages including that of the love of knowledge at the heart of scientific inquiry, how people can work together to overcome serious obstacles, and how science and social media can actually bring out the best in people.



[1] Jackson, MD, Spencer S. Engaging for a good cause: Sophia’s story and Why #BugsR4Girls. Annals of the Entomological Society of America.2017 110(5), 2017, 439–448 doi: 10.1093/aesa/sax055