[Phys-seminars] 2011-03-01 Lasers Seminar

ilana ibar at bgu.ac.il
Wed Feb 23 08:23:11 IST 2011


Lasers Seminar 

  DATE: 01-03-2011 

  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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