[Phys-seminars] 2011-03-01 Lasers Seminar
ibar at bgu.ac.il
Wed Feb 23 08:23:11 IST 2011
TIME: 3:30pm (Tue)
PLACE: Physics building (#54) room 207
Depicting brain's activity with an atomic magnetometer
Dr. Andrei Ben-Amar Baranga, Department of Electrical Eng., Ben Gurion
University, and Nuclear Research Center - Negev
Extensive scientific effort is underway worldwide towards the
understanding of one of the most intriguing human attributes, the mind.
The past decade has seen fascinating developments in human brain
activity imaging that have enabled researchers and clinicians to
specify which brain systems take part in generating thoughts,
emotions and actions. Yet, despite the progress to date, the
complexity of brain functioning require huge scientific and technical
efforts still to be done for brain imaging.
Stimulation of a neuron involves ion flux across the cytoplasmic
membrane, followed by a rapid change in membrane potential and
propagation of an electric pulse along the neuronal cell. The
resulting electric potential may be measured on the scalp by
electroencephalography (EEG), and the resulting magnetic field, by
magnetoencephalography (MEG). These two totally non-invasive techniques,
which provide complementary information, are sufficiently fast to
study the temporal aspect of the mental operations. Magnetic fields,
unlike electric potentials, are not affected by surrounding conducting
tissues and thus may reflect more accurately their source. However
the brain magnetic field monitored outside the scalp is very weak, a
milliard times weaker than earth magnetic field, and ultra high sensitive
magnetometers are required. MEG systems based on liquid-He Superconducting
Quantum Interference Device (SQUID) are commercially available today.
A pioneering technology for MEG based on a Spin-Exchange Relaxation
Free (SERF) atomic magnetometer was developed and published lately.
The atomic magnetometer does not require cryogenic cooling and is
therefore more reliable and substantially less expensive than the
SQUIDs, opening the way to lower cost machines. A SERF atomic
magnetometer operates at the BGU Physics Department and three-dimensional
magnetic field measurements in a single magnetometer cell was
demonstrated for the first time. The SERF capability of functioning
as scalar and vector magnetometer has been demonstrated too.
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