Brain imaging methods

While PET and iMRI methods allow identification of neural areas activated by respiratory stimuli, these brain-imaging methods cannot discriminate between sensory and motor activation. The pattern of RREP peaks provides neural indicators of the temporal sequence of respiratory sensation. However, RREP studies provide limited information on the specific neural nuclei of the respiratory sensory pathways to the activated discriminative and affective cortices (Bloch-Salisbury and Harver 1994 Bloch-Salisbury et al. 1998 Davenport et al. 1986, 1996 Davenport and Hutchison 2002 Harver et al. 1995 Knafelc and Davenport 1997,1999 Logie et al. 1998 Revelette and Davenport 1990 Webster et al. 2002 Webster and Colrain 2000a, b Zhao et al. 2002). 

Since the early 90s, noninvasive functional brain imaging of humans using NIR methods have been slowly gaining momentum despite existence of more established imaging modailties, such as PET, fMRI, and EEG. Part of the reason as stated previously, is because of its relatively high temporal resolution and its ability to monitor multiple tissue chromophores. The technique has been applied to adult as well as infant studies. NIR method is particularly suited for infant studies as the equipment, at least the CW kind, are minimally restraining, relatively safe, and portable [67]. Most neonatal studies focus on sensory stimulation such as visual, auditory and olfactory stimulations [69] [101] [89] [115] [6] [5], and cerebral disfunction [70, 71]. Our review will focus primarily on adult studies with some emphasis on defense and security applications. 

In SUMMARY, it would appear that a detailed knowledge of the pharmacokinetics of the main groups of psychotropic drugs is only of very limited clinical use. This is due to limitations in the methods for the detection of some drugs (e.g. the neuroleptics), the presence of active metabolites which make an important contribution to the therapeutic effect, particularly after chronic administration (e.g. many antidepressants, neuroleptics and anxiolytics), and the lack of a direct correlation between the plasma concentration of the drug and its therapeutic effect. Perhaps the only real advances will be made in this area with the development of brain imaging techniques whereby the concentrations of the active drug in the... 

Another brain imaging technique is magne-toencephalography (MEG).C n It has been uniquely valuable in mapping the sensory regions of the human cerebral cortex. Looking ahead, optical methods, which include use of infrared radiation, are also under development.0 They may not be adequate for study of the human brain but can be used for smaller animals, for studies of embryonic development, etc. 

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