It’s not every day that foundational physiological understandings of an organ system are reconsidered, overturned, or even added to in a significant way. Yet, when it does happen, it questions how we could have ever assumed that there wasn’t “more going on.” This week there have been 2 extraordinary discoveries using a 2-photon fluorescent imaging technique, 1 that utilizes fluorescent proteins to trace the movements of various cell types and processes. Activities, which have not been able to be mapped previously, are now becoming elucidated. In another article, we reported on the recent discovery of the hematopoietic ability of the lungs. But in addition, this week Stanford University Medical School researchers have discovered a new role, which the cerebellum plays in cognition.2
More Than Structural
The cerebellum has largely been considered a brain structure primarily responsible for more subconscious and “background” neural functions, such as patterned movement, and balance. This has been largely the belief because when the cerebellum becomes injured; these are the types of deficits that occur – loss of gait control and motor function. But this is currently under question.
Shining a Light on the Cerebellum
Granule cells consolidated in the cerebellum make up 80% of the neurons in the brain, but only 10 percent of its total volume. Because of their size, they have been extremely difficult to study. Recently, with the help of 2-photon calcium imaging utilizing fluorescent microscopy, a mouse model was able to show that granule cells become active during various types of reward response contexts, and also during reward anticipation.
Anticipation Activation
Mice were put into a situation where they were rewarded with sugar water after pushing a button. It was expected the granule cells would light up with the movement of their forearms, but the study revealed that granule cells also lit up in response to the anticipation, as well as the reward given. These were also different clusters of granule cells, indicating deeper cognitive operations occurring in the cerebellum in response to reward. After several days of learning, granule cell activity became more predictive, and entrenched. This discovery adds contextual richness to overall cognitive processing in regards to cerebellar/cerebral connections.
Sources:
- Looney, M. R. et al. Stabilized imaging of immune surveillance in the mouse lung. Nat. Methods 8, 91–96 (2011)
- Wagner MJ, Kim TH, Savall J, Schnitzer MJ, Luo L. Cerebellar granule cells encode the expectation of reward. Nature. 2017
Node Smith, associate editor for NDNR, is a fifth year naturopathic medical student at NUNM, where he has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine amongst the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend campout where naturopathic medicine and medical philosophy are experienced in nature. Three years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision.
