H. Robert Horvitz has devoted much of his career to studying the nematode worm Caenorhabditis elegans. Only 1 mm long and containing fewer than 1000 cells, C. elegans has proved to be remarkably informative for studying many biological problems, including the genetic control of development and behavior and the mechanisms that underlie neurodegenerative disease.
Author: Julie Pryor
2012 MEG Symposium: Applications to Cognitive Neuroscience
2012 Scolnick Prize Lecture: Roger Nicoll, MD
Dr. Roger Nicoll of the University of California, San Francisco delivered the 2012 Scolnick Prize lecture, entitled “Deconstructing and reconstructing an excitatory synapse,” at the McGovern Institute for Brain Research at MIT on Thursday April 19. 2012.
Understanding the brain basis of autism
Autism Speaks at the McGovern Institute
Dr. Okihide Hikosaka: 2012 Sharp Lecture in Neural Circuits
The inaugural Sharp Lecture was given on March 1, 2012 by Okihide Hikosaka of the NIH, a leading expert on brain mechanisms of motivation and learning.
Many objects around us have values which have been acquired through our life-long history. This suggests that the values of individual objects are stored in the brain as long-term memories. Our recent experiments suggest that such object-value memories are represented in part of the basal ganglia including the tail of the caudate nucleus (CDt) and the substantia nigra pars reticulata (SNr). We had monkeys look at many visual objects repeatedly in association with different but consistent reward values: half of the objects associated with a large reward (good objects) and the other half associated with a small reward (bad objects). Initially there was little effect of the object-reward association learning. However, after learning sessions across several days, CDt and SNr neurons started showing differential responses to the good and bad objects. In the end, SNr neurons reliably classified surprisingly many visual objects (nearly 300 in each monkey, so far tested) into good and bad objects. This neuronal bias remained intact even after >100 days of no training, even though the monkey continued to learn many other objects. The object value signals in the CDt and SNr are likely used for controlling saccadic eye movements, because many of the SNr neurons projected to the superior colliculus and electrical stimulation in the CDt induced saccades. Our results suggest that choosing good objects among many depends on the basal ganglia-mediated long-term memories. This basal ganglia mechanism may play an underlying role in visuomotor and cognitive skills.
Video Profile: Michale Fee
Michale Fee, an investigator at the McGovern Institute for Brain Research, studies birdsong in order to understand how the brain learns and generates complex sequences of behavior.
Detecting the brain’s magnetic signals with MEG
Magnetoencephalography (MEG) is a noninvasive technique for measuring neuronal activity in the human brain. Electrical currents flowing through neurons generate weak magnetic fields that can be recorded at the surface of the head using very sensitive magnetic detectors known as superconducting quantum interference devices (SQUIDs).
MEG is a purely passive method that relies on detection of signals that are produced naturally by the brain. It does not involve exposure to radiation or strong magnetic fields, and there are no known hazards associated with MEG.
Magnetic signals from the brain are very small compared to the magnetic fluctuations that are produced by interfering sources such as nearby electrical equipment or moving metal objects. Therefore MEG scans are typically performed within a special magnetically shielded room that blocks this external interference.
It is fitting that MIT should have a state-of-the-art MEG scanner, since the MEG technology was pioneered by David Cohen in the early 1970s while he was a member of MIT’s Francis Bitter Magnet Laboratory.
MEG can detect the timing of magnetic signals with millisecond precision. This is the timescale on which neurons communicate, and MEG is thus well suited to measuring the rapid signals that reflect communication between different parts of the human brain.
MEG is complementary to other brain imaging modalities such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), which depend on changes in blood flow, and which have higher spatial resolution but much lower temporal resolution than MEG.
Our MEG scanner, an Elekta Neuromag Triux with 306 channels plus 128 channels for EEG, was installed in 2011 and is the first of its kind in North America. It is housed within a magnetically shielded room to reduce background noise.
The MEG lab is part of the Martinos Imaging Center at MIT, operating as a core facility, and accessible to all members of the local research community. Potential users should contact Dimitrios Pantazis for more information.
The MEG Lab was made possible through a grant from the National Science Foundation and through the generous support of the following donors: Thomas F. Peterson, Jr. ’57; Edward and Kay Poitras; The Simons Foundation; and an anonymous donor.
Video Profile: Yingxi Lin
Yingxi Lin, a member of the McGovern Institute for Brain Research, uses molecular, genetic, and electrophysiological methods to understand how inhibitory circuits form within the brain, and how they are shaped by activity and experience.