Breakthrough had the privilege of listening to Dr. Jasanoff and Dr. Boyden speak at Sidney Pacific Presidential Fellows Distinguished Lecture at MIT, where they introduced the history of neuroimaging, limits and challenges of the current techniques, and the future role they hope neurobiological engineering will take in order to deepen our understanding of the brain. Part one will introduce the professors and give an overview of the history of neuroimaging and the limits of the current techniques, while Part two of this article will focus on the current challenges and the future roles Dr. Jasanoff and Dr. Boyden see as pivotal for neurobiological engineers.
Introduction of the Professors
Dr. Jasanoff is the Professor of Biological Engineering, Brain & Cognitive Sciences, Nuclear Science & Engineering at MIT. He is focused on the design and application of new contrast agents of the functional magnetic resonance imaging (fMRI) that may help define spatiotemporal patterns of neural activity with far better precision and resolution than current techniques allow. His hope is to combine the specificity of cellular neuroimaging with the whole brain coverage and noninvasiveness of conventional fMRI, which will allow one to build explanatory models of neural network function in animals.
Dr. Boyden is the professor of biological engineering and brain and cognitive sciences and leads the Synthetic Neurobiology group, which not only develops tools for analyzing complex biological systems such as the brain, but also applies them systematically to reveal ground truth principles of biological function as well as to repair these systems. These technologies, created often in interdisciplinary collaborations, include expansion microscopy, which enables complex biological systems to be imaged with nanoscale precision, optogenetic tools, which enable the activation and silencing of neural activity with light, and optical, nanofabricated, and robotic interfaces that enable recording and control of neural dynamics.
History of Neuroimaging
When one reflects on the progresses made in neuroimaging, one could start from Ramón y Cajal’s beautiful artistry (cf. Butterflies of the soul) and take pride in how far we have come since then.
The new neuroimaging tools, such as functional magnetic resonance imaging (fMRI), computerized tomography (CT) and positron emission tomography (PET) are commonly used for medical diagnosis for neural spatial map data and have been used to comprehensively delineate the brain. For the anatomy of the connections between the neural tissue architecture, the diffusion tensor imaging (DTI) technique utilizes the white fat tissue called myelin, which insulates the neuronal communicating fibers. Because water and fat do not mix, diffusing water molecules throughout the brain allows the scientists to isolate the neural connections for neuroimaging.
Moreover, not only do we have impressive neural spatial map data, the current techniques also allows us to measure amount of activity happening within each area of the brain through electroencephalogram (EEG), which measures the electrical activity of the brain in real time.
Limitations of Current Neuroimaging Techniques
We have evidently come far compared to what we had a mere century ago, but Dr. Jasanoff, one of the program directors of MIT’s Neurobiological engineering lab, has remarked that there is much more we don’t know than what we do know.
This may come as a surprise to those who see current neuroimaging techniques as the finishing product to uncover all the mysteries of the brain. While they did uncover a significant amount of knowledge about what is happening inside of our brain, Dr. Jasanoff noted the lack of specificity of the current techniques. With the current state of arts, one cannot have high spatial and temporal resolution.
This means that we cannot identify the patterns of activity that underlie the neural pathways with the current neuroimaging techniques because they have a poor temporal resolution, which means that the flashes of activity we see do not tell us of exactly which neurons are interacting. For example, if you saw a city from a satellite in the outer space, you may see that there is life at the city, but have no idea exactly what is going on within the city. If we chose to use EEG that has a high temporal resolution, we have no idea which areas are firing because we are only getting the action potential with an ambiguous source. It is like standing outside a hall and hearing people fight in a foreign language. Without seeing inside the room, we do not know whether they are indeed fighting, practicing for a performance, or simply prefer to talk in a loud voice. Hence, Dr. Jasanoff has called for the need of neurobioloigcal engineering to create tools that could extract more data about our brain to deepen our understanding of the neural pathways that underlie our behavior and make us who we are.