Professor Mike Dash of the psychology department explores the question, how does the brain generate our consciousness? He studies this difficult concept by examining learning and memory in rats, observing how the coordinated activities of groups of neurons affect cognition and the brain.
“As these groups of neurons come together and coordinate activity,” Dash asked, “how does this help support functions we’re interested in and how does this support the brain itself?”
The field of neuroscience research mostly focuses on two broad areas at either end of consciousness. There are cellular/molecular neuroscientists, who explore the details behind the individual mechanisms responsible for the communication of neurons. There are also systems neuroscientists, who draw larger conclusions about function in various brain areas. Dash considers himself between these two areas.
“There are comparably fewer individuals who sit in that middle ground and in order to link the cellular/molecular mechanisms with the systems,” Dash said. “We have to look at the coordination of the activity of the neurons.”
This year, Dash’s lab includes four seniors pursuing two different projects to study this coordinated neuronal activity. Stella Lentzou ’18 and Josh Goldenberg ’18 are working on a project about how competing neurons communicate so that when there are several valid responses available, one response wins out.
Kisha Kalra ’18 and Deniz Bingul ’18 are studying how inducing learning through long-term potentiation (LTP) affects metabolic energy changes in the brain.
LTP is the strengthening of synapses, the communication site between two different neurons, that occurs following the use of the synapse. Strengthening the connections of some synapses and not others will bias which groups of neuronal connections form.
Lentzou and Goldenberg’s project builds on the findings of a previous lab group that observed two different strategies adopted by rats to learn where to find food in a T-maze. Food was consistently placed in one arm of the maze (e.g. the left arm) and the rats adopted either a place strategy or a body strategy.
Some rats learned to follow certain external cues, such as posters on the wall, in order to reach the food, a place strategy. Other rats learned to turn their bodies to the left to find the food, a body strategy.
Although the rats all came from the same strain, meaning they are genetically identical, 50% adopted the place strategy and 50% adopted the body strategy. Lentzou and Goldenberg seek to address why these seemingly identical rats become biased towards one strategy over the other.
Existing literature on the subject indicates that the hippocampus is responsible for place strategy, while the dorsal striatum is responsible for body strategy. To examine what is happening in the brain, Lentzou and Goldenberg record the electromagnetic activity of groups of neurons in these two areas, plus the prefrontal cortex, before, during, and after maze learning.
As the team begins to analyze the data, Lentzou said they are looking for answers to questions such as, “Is there a correlation between brain activity before and after maze exposure? Is one area more active than the other? Is there any kind of synchronous activity? For example, if we see that the hippocampus and dorsal striatum have synchronous activity, it means that they’re talking to each other.”
“How might this brain activity produce cognition and are the rats conscious of their actions in the maze?” Lentzou asked, indicating this as the central question of their research.
On the other hand, Kalra’s and Bingul’s project asks what sort of metabolic demand the strengthening of synaptic connections imposes on the brain.
“We know the brain is incredibly greedy,” Dash said. “The brain is two percent of our body mass, but it uses 20 percent of our energy supply. Neuronal activity is the major driver of energy consumption within the brain.”
By inducing learning through a brief electrical stimulation, Kalra and Bingul can measure the strength of the synaptic connections before, during and after learning. Simultaneously, they are able to record the concentrations of glucose, oxygen, and lactate in these connections.
“Lactate is a byproduct of glycolysis and our hypothesis is that the brain increasingly relies on glycolysis, [the breakdown of glucose to provide energy for the brain], when under energetic strain,” Kalra said.
“Is learning like running a marathon for the brain?” Dash asked, putting the question in less technical terms.
By measuring the concentrations of glucose, oxygen and lactate, the lab can explore how does availability of glucose, used for energy, changes as a consequence of strengthened synapses. The researchers also gained insight into how the energy needs of stimulation cause the brain to compensate.
Answers to these challenging questions do not come easily or quickly. The students often spend hours in lab. Handling the demands of lab and their own class work and extracurricular activities is a true balancing act. Nonetheless, it is an experience the students describe as very rewarding.
Kalra remembered first entering the lab and thinking, “how will I ever be able to do any of this?”
Now, she finds herself getting excited over lactate levels that were previously meaningless to her. Lentzou has also enjoyed being involved with every step of the lab process, which allows her to understand all the components of the experiments.
“The Dash lab helped me realize that I want to make it my life purpose to answer the questions I have about how the brain works,” said Lentzou. “I am applying for a PhD program in this area to gain the tools I need to answer those questions.”