Functional neuroimaging has led to important advances in our understanding of the neural events that support behavior and has emerged as an important technique in the study of psychiatric and neurological disorders such as schizophrenia, dementia, depression, and epilepsy. Magnetoencephalography (MEG) is a particularly valuable neuroimaging tool because it achieves sub-centimeter spatial and millisecond temporal resolution by directly measuring magnetic fields produced by neural currents, typically on the order of 100 femtotesla. MEG has traditionally been performed with highly sensitive superconducting quantum interference devices (SQUIDs). Traditional SQUID systems require large capital expenditure and high maintenance costs because they must be maintained at liquid helium temperatures. As a result, MEG’s potential as a research and clinical tool has yet to be realized. Atomic magnetometers (AMs) are a potential noncryogenic alternative to SQUIDs and have recently demonstrated sub-femtotesla sensitivities [1]. In AMs, a vapor cell of alkali metal is heated to 200ºC producing a high density atomic cloud. Circularly polarized laser light aligns the electron spins of the cloud to create a collective magnetic moment. The interaction of this moment with an external magnetic field changes the optical properties of the vapor. A probe laser beam monitors this change to produce an output signal proportional to the magnetic field. Although MEG with atomic magnetometers has been demonstrated [2], little effort has been spent to develop AMs that could be packaged in a whole head MEG system. With this goal in mind, we have designed a small-profile, rubidium-based AM that operates inside a fiberglass vacuum vessel. This allows packing and placement of the AMs in configurations similar to those in current SQUID based MEG systems. The current sensitivity of the magnetometer is 15 fT/sqrt(Hz) between 5-50 Hz and < 25 fT/sqrt(Hz) out to 100 Hz. Additional near term work includes the implementation of gradiometry to remove common mode noise, measurements in human subjects, and comparison of AMs to a SQUID-based commercial MEG system.
[1] I. K. Kominis, T. W. Kornack, J. C. Allred, and M. V. Romalis, Nature 422, 596-599 (2003).
[2] H. Xia, A.B. Baranga, D. Hoffman, M.V. Romalis, Appl. Phys. Lett. 89, 211104/1-3 (2006).
Refreshments will be available before the seminar at 3:00 pm, in the PandA lobby.
Individuals with disabilities who need an auxiliary aid or service to attend or participate in P&A events should contact Daniel Sandoval (phone: 505-277-2616, email: daswerto@unm.edu) well in advance to ensure your needs are accommodated. Event handouts can be provided in alternative accessible formats upon request. Please contact Mr. Sandoval if you need written information in an alternative format.
University of New Mexico Department of Physics and Astronomy -
MSC07 4220 -
800 Yale Blvd NE
Albuquerque, New Mexico 87131-0001
Phone: (505) 277-2616
Fax: (505) 277-1520
Comments/questions about this web page? Email webmaster@phys.unm.edu
Spring 2009
Individuals with disabilities who need an auxiliary aid or service to attend or participate in P&A events should contact Daniel Sandoval (phone: 505-277-2616, email: 
People
Faculty