L to R: Our demonstration of TMS; demonstration of tDCS; and our brain cake! (Click for larger images)
Can neurons do the electric slide? Well, probably not, but they are dancing a complex biochemical ballet and this results in electrical signals traveling all through the brain. At the close of yesterday afternoon, and all day today we learned how neuroscientists measure, modify, and manipulate those neuronal signals.
Hands-down the winner for most creative element of boot camp so far was our “brain cake” (see photo above). The cake was served at the end of the day, during our “applied psychopharmacology” session (read: beer hour). We were also exposed to some amazing uses of the Brain Computer Interface (BCI). BCI can already be used to have a monkey control a robotic arm, play the game Pong, and other amazing things. To understand how this is done, and what might happen in the future, continue reading. (Click below for more).
I. Play-by-Play
Fatigue is starting to set in a bit, and it was good that our schedule today involved multiple breakout sessions and a field trip. All of today’s presentations concerned aspects of electrophysiology. We ended Wednesday talking about both how you measure electrical activity in the brain (with EER, ERP, and MEG), and how you stimulate electrical activity (with TMS, DCS, and DBS). Today we started with a journal-club style breakout session to talk about an electrophysiology article. Similar to our breakout sessions on fMRI research, our goal was to become better consumers of electrophysiology research. After the breakout session, we took a field trip to see David Wolk’s lab, to see Transcranial magnetic stimulation (TMS) and Transcranial direct current stimulation (tDCS) in action. The morning ended with a forward-looking lecture by bioengineering professor Ken Foster. Ken talked to us about a number of ideas – some already in action, some fanciful – related to Brain Computer Interface (BCI).
The regular lunch break was replaced with a working lunch to discuss the controversial paper “Voodoo correlations in social neuroscience”. The paper has drawn considerable attention both within and outside of neuroscience, and it provided for good discussion of neuroscience methodology. After lunch we settled down for some of the nitty-gritty on neuronal biochemical processes. This neurochemistry lesson focused on the chemical reactions necessary to create neuron activations. Once the basic chemistry was covered, we then talked about how drugs could be used to affect neuronal activity. Psychopharmacology, as the field is known, is exploring many ways in which drugs may improve behavioral outcomes, e.g. countering the effects of Parkinson’s Disease. We ended the day with a second breakout session, and had four different session options covering:
- Controversies in pediatric psychopharmacology
- Controversies in the pharmacologic treatment of pain
- The chemistry of love
- Behind the scenes of a psychopharmaceutical launch
II. Important Lessons
The mind, we were reminded once again, is mind-boggling. Consider this (which we learned this afternoon). The brain has somewhere between 100 billion to 1 trillion neurons. These neurons communicate with one another through synapses, and there are a thousand synapses per neuron. Those are a lot of signals to keep straight. But we’re not finished yet. If we go down another level, to the biochemical reactions that allow for neuronal communication, then we have to consider an incredibly large number of ion channels and receptors. In short, to use Dr. Kaplan’s very scientific terminology, this adds up to a “completely ridiculous” number of connections in the brain. Indeed, even our best analogies for how the brain works (e.g. like an amazing super-computer) don’t begin to capture its capabilities.
Nevertheless, neuroscientists are making strides in improving our understanding of at least some parts of this insanely complex system. It’s helpful to start with the neurobiology and neurochemistry, and for easy to access introductions you might look here or here, and for a more detailed course see this from MIT. These chemical processes produce electrical signals which can be measured by researchers. Researchers can measure activity either via the scalp with Event-Related Potential (ERP) [measured using
Electroencephalography (EEG)], or in a separate machine using Magnetoencephalography (MEG). ERP measures the electrical field emanating from the brain, and MEG measures the magnetic field. Both methods are aiming to help us understand what parts of the brain are emitting certain electrical or magnetic fields. In this way, we can more directly see when parts of the brain are ‘activated’.
A challenge with these approaches of course is that they are outside the scalp. Because signals are moving through many layers of tissue and eventually the scalp, the signals can be difficult to measure with precision. In general, EEG is most sensitive to brain areas that are parallel to the scalp, and MEG is most sensitive to those areas that are perpendicular.
Measuring brain activity is only one aspect of electrophysiology. The flip-side is electrical stimulation: using external stimuli to get certain neurons (or more precisely - ensembles of neurons) to fire. Brain stimulation is done through one of three ways: Transcranial magnetic stimulation (TMS), Transcranial direct current stimulations (tDCS), or Deep brain stimulation (DBS). To get a sense of what these mean, check out this short article on TMS, this video for TMS, this video for tDCS, and this video for DBS. The logic behind all three methods is the same: stimulate part of the brain, hypothesizing or expecting to produce a particular behavioral outcome. One of the clinical applications of TMS is for the treatment of depression, and the NeuroStar TMS therapy for depression has gained FDA approval.
The clinical applications of stimulation, as well as the tDCS methods, are still new and evolving. The message we received today was a mix of hope and caution. Be hopeful that we may learn a lot about how the brain works (and in turn make it work better), but be cautious that such knowledge may take a long time to accumulate.
III. Who’s at boot camp with me?
Tomorrow one of my fellow boot camp attendees, Denise Clegg, will be leading a meditation session based on principles from positive psychology. Denise is the Contract Program Officer for the Positive Neuroscience program at the University of Pennsylvania, and is an editor for PositivePsychologyNews.com. Positive psychology is a growing field, and you can learn more from the Penn Positive Psychology Center. It will be interesting to see how positive psychology extends into positive neuroscience in the years to come.
