Princeton Insights

May 14, 2020May 14, 2020

Learning to control the brain

Review written by Eleni Papadoyannis (PNI)

How do humans control a complex system like the brain? Over the years, neuroscientists have discovered numerous methods to do exactly that. Applying chemicals, such as muscimol, can drive inhibition to shut down a brain region. Alternatively, shining light can selectively activate certain cell types through the photo-sensitive protein channelrhodopsin. Sending electrical impulses via electrodes in deep brain stimulation (DBS) can also control regional activity in humans. Causal manipulation of the brain not only offers incredible insight into hypotheses relating neural activity to behavior, but also serves as a clinical tool. Electrical and magnetic stimulation methods have been used as therapies for treating patients with a variety of diseases and disorders, such as using DBS to control motor disruption in Parkinson’s. A major limitation with many stimulation methods, however, is that the protocol is static while the brain is plastic—over time, brain responses to stimulation may no longer elicit what was intended as the brain naturally changes.

May 6, 2020May 6, 2020

Understanding visual navigation

Review written by Sara Camilli (QCB) and Adelaide Minerva (PNI)

As we go about our daily lives, we often do not consciously think about all the real-world landmarks that we use to position ourselves in space. Yet, as we walk to our local coffee shop or go for a jog in the park, our brain is continuously updating its internal representation of our location, which is critical to our ability to navigate the world. However, we also know that humans and a number of animals can update this internal representation of their position in space even in the absence of external cues. This phenomenon, known as path integration, involves interaction between the parietal cortex, medial entorhinal cortex (MEC), and hippocampus regions of the brain. Prior work has shown that grid cells in the MEC have firing fields that are arrayed in a hexagonal lattice, tiling an environment. Further, there is evidence of inputs to the MEC that encode the velocity at which an animal is moving, which can be used to update the animal’s internal representation of its position. Together, these features support a role of the MEC in path integration.

April 26, 2020May 5, 2020

How do our beliefs converge?

Review written by Crystal Lee (PSY) and Adelaide Minerva (PNI)

Recently, the term “fake news” has been solidified as a colloquial term. Indeed, it seems the world has seen an increase in the spread of misinformation. What is particularly troubling about this trend is that psychology studies show that increased exposure to information (both true and false) increases our beliefs about its truthfulness, and what we believe to be true impacts our behavior in important ways (e.g., voting). When we consider the spread of “fake news”, how do we know what is true, and how do we protect ourselves from misinformation?