Introduction

The Human Connectome Project is an National Institute of Health (NIH) initiative that is mapping all of the neural connections in the human brain. By mapping the circuitry of the brain, researchers could potentially identify anomalies in individual brains with conditions such as schizophrenia, dyslexia, and autism, conditions that have no certain origin or cause.

Since this is such a huge project and it is still ongoing, I will be analyzing data from the Budapest Reference Connectome. This is a much smaller subset of the entire project.

My intended research question is: Is there a noted difference in connectivity between the left and right hemisphere?

Why Should We Care?

There is a theory that right-handed individuals are “left-brain dominant”. This is called brain lateralization. And for a long time, the converse was also believed to be true: Left-handed individuals are “right-brain dominant”. However, this claim was later debunked. It turns out that most left-dominant humans, like right-handed people, are “left-brain dominant”. Thus, since the Human Connectome Projet is striving to create a model of a generic human brain, this left-brain dominance left hemisphere as compared to the right.

The Data

I have chosen to analyze the Budapest Reference Connectome because it is a subset of the much larger Human Connectome Project. The most up-to-date version of the data that I will be working with incorporates mappings of 477 human brains. There does not exist one generic version of human brain circuitry, thus the mappings were overlapped and the edges of the connections were averaged. Within the data, each node is identified by its region and parent node region and where it projects to. The connection between the origin node and the receiving node has an associated weight that is determined by the average length of all 477 brains. I will make the assumption that this weight is indicative of the strenght of the connection.

What Am I Gonna Do?

I will first dissect the data between nodes that project within the left and right hemisphere. I will remove any connections that project from one hemisphere to the other. Then, I will compare statistics on the right and left hemispheric connections. This will include summaries on the strength (weights) of the connections as well as the number of interconnections that exist in each hemisphere.

How Will This Help the Consumer?

The consumer in this scenario would be neuroscientists concerned with the anatomy and physiology of the brain. Many upper-level cognitive functions (i.e., language processing, motor control, etc.) are laterally distributed. That means that the most regions and the functions associated with those regions have a mirrored counterpart in the opposite hemisphere that has nearly identical functionality. My project is searching for the differences between the hemispheres. Thus, if there is a difference in connectivity between the left and right hemisphere, what does that imply about the lateralization of cognitive functions?