[د/سمير المليجى]

Prof. Dr. Robert Turner


Physics in neuroscience

neuroPhysics


In recent years, the physics played a major role in the rapid development in the field of

Cognitive Neuroscience. Early nineties were by scientists in the United States, especially here
in Boston, Minneapolis, Murray Hill and Washington, develops methods to make visible brain functions can. This, now widely used, methods using magnetic resonance imaging (MRI) and functional MRI are called (fMRI). Also succeeded physicists the interpretation of measurements of the magnetic field which is generated by brain activity to improve (MEG) to a great extent. The physics of electromagnetic fields, nuclear spins and the biophysics of blood and brain tissue were pooled to provide non-invasive methods that can detect brain activity spatially and temporally within a millimeter within a millisecond. The methods allow the exploration of profound neuropsychological issues, such as the organization of human brain functions and the relationship between mind and brain. An improved understanding of normal brain functions is hoped that the development of empirically based treatment approaches for a number of neurological and psychiatric disorders.
For this reason the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig was established the Department of Neuro Physics at. In order to advance to the limits of imaging techniques in neuroscience (and possibly beyond), it is necessary to combine the power of MR physicists with those of neuroanatomists, experts in image analysis, engineers, and neuropsychologists. The department has an ultra-modern high-field magnetic resonance imaging. This tomograph is approved for human studies and has a field strength of 7 Tesla. This is more than twice the field strength of the strongest magnetic resonance imaging in clinical use. In addition, scientists use the facilities of the institution, such as a MEG device and two 3 Tesla MRI scanner.
Cartography of the brain, functional and anatomic
The main challenge is to answer the following question: What new insights into the structure and function of the human brain we gain by using new method of magnetic resonance imaging? Because of the excellent safety record of magnetic resonance imaging their techniques can be easily explored with volunteers. The high field strength allows the use of very high spatial resolution, so that structures can be distinguished under a millimeter in size. In addition, the arrangement of the white matter in the brain that consists of long main nerve cords that connect the various brain regions together, are explored with greater accuracy. The changes in the MR image signal generated by local brain activity can be measured with greater sensitivity and spatial resolution. So there is the possibility of an improved and more detailed scientific understanding of the interplay between functions and structures in the brain.
To most suitable answers to the question "Which neural area has what function?" To find the imaging neuroscience has so far rely on the relatively loose connection between spatial location, structure of the cortex and the histological analysis of the cell structure in brain samples (such as Brodmann (1909)). Now we know that many areas of gray matter when scanning using magnetic resonance imaging show a characteristic appearance. So we are permitted with great precision to find the neural carrier of certain brain processes. The aim of mapping many of these areas, to explore the individual structure of the gray matter, is in sight.
In addition, changes in brain structure, such as the thickness of the gray matter, which is known to change with repeated experience and practice, much easier than at lower magnetic fields are investigated.
Technical Requirements
The best use of these powerful devices requires new imaging techniques, new hardware and great caution with regard to the safety of the subjects. In normal field strength there are recognized and highly effective safety standards. The contact with magnetic fields of high intensity shows no harmful side effects. This has been tested with a large number of subjects worldwide extensively and there is no physical reason to expect side effects. At high magnetic fields, but there is a safety issue for the medical technology still needs to develop an appropriate course of action. To produce images using magnetic resonance imaging, magnetization of the spins of protons in the water molecules in the tissue should be encouraged. These high frequency pulses are needed which can heat the brain tissue in principle. The careful precautions on the part of the manufacturers of medical technology have to be at high field strength complemented by calculations of the electromagnetic field to ensure the safe use of magnetic resonance imaging. These calculations also help to identify the most effective techniques to study. The department Neurophysics are to achieve their full resources and experts for radio frequency modeling and hardware.