Brain function,study techniques

Neurochemists continue to improve the methods they use to measure and analyze chemicals of the brain. They have also developed techniques to study how neurons transmit messages across synapses to other neurons, and how these messages affect the recipients. Synaptic transmission is critical in brain function, and neurotransmitter imbalances have been associated with disorders such as depression and schizophrenia as well as drug abuse. Although the cause or causes of these conditions are not necessarily as simple as too much or too little of a certain neurotransmitter, chemicals such as dopamine and serotonin are undoubtedly involved. Neurotransmitters have been excellent starting points for further, ongoing studies into these issues. 

The last two decades have seen the introduction of several distinct functional imaging techniques that can be used to investigate centrally active compounds working in the brain in vivo. These techniques provide windows through which to observe phenomena in the intact and fully functional central nervous system. When applied to studies with human volunteers or patients one can obtain information that cannot be extrapolated from animal models, and from areas such as the brain and neurotransmitter systems that would otherwise be inaccessible in vivo. When combined with peripheral measurements and objective and subjective assessments of behavior, these methods can be used to explore how psychopharmaceuticals influence central nervous svtem activity and behavior. Moreover, compounds with a known mechanism of action can be employed as tools to understand how different elements of the central nervous system work. 

A relatively new technique that uses radioactivity to study body processes and diagnose malfunctions is commonly called positron emission tomography (PET). In this technique radionuclides that decay by positron emission are incorporated into compounds. For example, brain function can be studied by incorporating 1gC into glucose, which is the main source of energy for the brain. By studying how this labeled glucose is metabolized in the brain, doctors can discover abnormalities caused by diseases such as cancer, Parkinson s disease, and epilepsy. 

The wide variety of morphological, physiological, and biochemical information available from the multitude of MR techniques, which allow sophisticated combinations of methods to be applied to individual neurological studies. This is one reason that MRI is often the best choice for neuroimaging studies, as the combination of multiple methods in one study can provide a wide array of coregistered information on the effects of disease and experimental therapies on brain function and biochemistry. 

Whittaker, V. P. (1965) The application of subcellular fractionation techniques to the study of brain function. Progr. Biophys. molec. Biol., 15,39-96. 

NMR can be used for the accurate determination of nuclear moments. It can also be used in a sensitive form of magnetometer to measure magnetic fields. In medicine, magnetic resonance Imaging (MRI) has been developed, in which images of tissue are produced by magnetic-resonance techniques. Functional MRI (fMRI) can detect changes in blood flow that accompany neural activity and is therefore used to study brain function. See Feature. 

Thus, fMRI activation has a potential for the study of brain function in brain AVMs, but larger series are necessary to evaluate the liability of this technique. 

Neurophysiological techniques have achieved less prominence as investigational tools for study of trace elements in neurobiology, but such work is described here in relation to deficiencies of iron and zinc and for analysis of the toxic consequences of lead and mercuiy. As mentioned previously, behavioral measures provide very sensitive monitors for early changes in brain function and several chapters deal specifically with such measurements. 

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