Christopher I. Moore on Gamma Oscillations
New Hot Paper Commentary, September 2010
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Figure 1: View larger image with description in tab below. |
Article: Driving fast-spiking cells induces gamma rhythm and controls sensory responses
Authors: Cardin, JA;Carlen, M;Meletis, K;Knoblich, U;Zhang,
F;Deisseroth, K;Tsai, LH;Moore, CI |
Christopher I. Moore talks with ScienceWatch.com and answers a few questions about this month's New Hot Papers paper in the field of Neuroscience & Behavior.
Why do you think your paper is highly
cited? Does it describe a new discovery, methodology,
or synthesis of knowledge?
The paper showed that driving a specific kind of cell (fast-spiking interneurons) with light pulses induces gamma oscillations. This finding is potentially highly cited for 3 reasons. First, it uses a relatively new technology (optogenetics) in the in vivo brain to allow us to control brain circuits with light. Second, it provides causal evidence for a key hypothesis in our field, that these interneurons help mediate gamma rhythm emergence.
Third, gamma oscillations are thought by many to be key for optimal information processing in the brain (some have even gone so far as to think they are important to consciousness). However, this theory is controversial. As such, the ability to induce this rhythm at will is an interesting advance as a method in itself.
Would you summarize the significance of your paper
in layman's terms?
Gamma oscillations—rhythmic changes in brain activity at a rate of ~40 times per second—are thought by many to be important for communication in the brain, facilitating processes like attention or even consciousness. This conclusion, however, is highly debated in neuroscience. This paper provides useful data as to how these rhythms emerge in the brain, and uses light pulses to control cells, an interesting method of brain control.
How did you become involved in this research, and
how would you describe the particular challenges, setbacks, and
successes that you've encountered along the way?
My laboratory studies how dynamics in the brain—fluctuations in its processing ability on millisecond to second time scales—influences information flow. Specifically, we study the neocortex and its role in perception. Gamma oscillations are a key signature of dynamics in neocortex and they vary with perceptual state and task, so working on this problem was a natural extension of our work.
Where do you see your research leading in the
future?
This initial study is limited by the fact that we induced brain states in anesthetized animals. Because the techniques used are non-painful, we are now seeing how awake behavior (for example, if the mouse is sleepy or actively engaged in sensing) influences our ability to induce gamma.
Do you foresee any social or political
implications for your research?
Gamma oscillations are altered in a variety of diseases, including autism
and schizophrenia. Understanding how these rhythms emerge—and knowing
how to control them—could provide useful information on these
maladies and ultimately in how we should treat them.
Christopher I. Moore
Associate Professor
McGovern Institute for Brain Research
MIT
Cambridge, MA, USA
KEYWORDS: FAST-SPIKING CELLS, GAMMA RHYTHM, SENSORY RESPONSES, NEURONAL SYNCHRONIZATION, ELECTRICAL SYNAPSES, CORTICAL NETWORKS, FAST OSCILLATIONS, CORTEX, INTERNEURONS, BRAIN, SCHIZOPHRENIA, GENERATION, ATTENTION.
Figure 1:
Figure 1: In this study, the researchers made specific cell types sensitive to light, so that shining a blue laser on the brain selectively activated only those neurons. One cell type they engineered to be sensitive to light was 'fast-spiking' (FS) inhibitory interneurons of the neocortex (shown in yellow in 'a'). When these cells were activated--but not when excitatory cells were similarly driven--the cortex showed an enhanced 'gamma' rhythm at 40 cycles per second (Hz). An example of this kind of optically induced electrical rhythm is shown for local field potential recordings (LFP) from the neocortex in panel 'b.' The gamma rhythm is typically associated with heightened attention, and alterations in this rhythm are a hallmark of neurologic and psychiatric diseases such as schizophrenia. This new approach not only advances our understanding of function in the normal brain, but also provides a powerful model system for probing alterations in brain dynamics in models of disease.