Brain activity studies with high-Tc SQUID based focal MEG
The brain is the organ that is perhaps most fundamental to our humanity and yet it remains frustratingly mysterious to even the most knowledgeable researchers and clinical practitioners. MedTech West is developing a new tool for studying the human brain that can be used to expand our understanding of it while improving diagnosis and intervention of brain diseases and pathologies.
Our high-Tc SQUIDs are a new generation of MEG sensors that improve signal-to-noise ratios and enable a more fine-grained study of brain activity when compared to the state-of-the-art in MEG. The passive and non-contact nature of the recording system makes it easier to implement than EEG. Our technology is also more than a 100 times faster than fMRI when it comes to following rapid brain signals and activity. In the future, neuroscientists will be able to safely and effectively explore new frontiers of the functioning brain while neurosurgeons will be able to treat their patients with improved interventions and higher confidence in the safety of invasive surgical interventions.
Magnetoencephalography (MEG) is a technique that is being used increasingly in research and emerging in clinical practice for recording brain activity by sensing the weak magnetic fields generated by the flow of neural currents in the brain. The method is non-invasive, safe (as opposed to PET that requires radioactive tracers), and has exceptional temporal resolution, typically less than 1 ms (in contrast to the seconds required for fMRI). Unlike the liquid-helium cooled low-Tc superconducting quantum interference devices (SQUIDs) that have been at the heart of modern MEG systems since their invention, high-Tc SQUIDs can operate with liquid nitrogen cooling. The relaxation of thermal insulation requirements allows for a reduction in the stand-off distance between the sensor and the room-temperature environment from a few centimeters to less than a millimeter, where MEG signal strength is significantly higher. Despite this advantage, high-Tc SQUIDs have yet to be exploited to their full potential in clinical or academic MEG systems.
We are presently exploring the capabilities high-Tc SQUID-based MEG may have in providing new information about brain activity due to the close proximity of the sensors to the head. We have performed novel single- and two-channel high-Tc SQUID MEG recordings of spontaneous brain activity in human subjects. The activity observed consists of modulation of two well-known brain rhythms: the occipital alpha rhythm and the mu rhythm found in the motor cortex. Furthermore, we have recorded unusually high-amplitude occipital theta-rhythm activity. Despite higher noise-levels compared to their low-Tc counterparts our high-Tc SQUIDs demonstrate excellent signal-to-noise-ratios in these MEG recordings. We anticipate our measurements to be a starting point for more sophisticated investigations with e.g. a closely-spaced array of high-Tc SQUIDs that could be used to better localize brain activity. Our results indicate the utility of high-Tc technology in MEG recordings of a broad range of brain activity.
Because they come closer to the head, high-Tc SQUIDs improve spatial resolution and sensitivity during recordings of the functional brain. These focal and high-sensitivity capabilities open the door to a host of novel neuroscience applications while potentially revolutionizing the way doctors and clinicians diagnose and treat diseases of the brain.
MedTech West partner
Dr. Justin F. Schneiderman, Department of Clinical Neuroscience and Rehabilitation, University of Gothenburg.
Prof. Mikael Elam, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital.
Dr. Anders Hedström, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital.
For more information on this project, contact Henrik Mindedal at firstname.lastname@example.org
Öisjöen, F., Schneiderman, J.F., Figueras, G.A., Chukharkin, M.L., Kalabukhov, A., Hedström, A., Elam, M., & Winkler, D. High-Tc superconducting quantum interference device recordings of spontaneous brain activity: Towards high-Tc magnetoencephalography. Applied Physics Letters, 2012, 100(13), p 132601. http://dx.doi.org/10.1063/1.3698152