Neural activity

Ikeuchi Y, Hirai H, Okada Y, et al Excitatory and inhibitory effects of toluene on neural activity in guinea pig hippocampal slices. Neurosci Lett 138 63—66, 1993... 

Lasareff put forward a chemical theory in which each receptor was responsive to only a single taste, and that applied stimuli caused the decomposition of a material within the cell. This decomposition produced ions which then excited the nerve endings in the papillae, the concentration of the ionized products determining the magnitude of the neural activity. 

He reported that sensory neural-activity is a function of the region of innervation, and not of the nerve innervating that area. 

A PET scan requires a substance called a tracer. A suitable tracer must accumulate in the target organ, and it must be modified to contain unstable radioactive atoms that emit positrons. Glucose is used for brain imaging, because the brain processes glucose as the fuel for mental and neural activities. A common tracer for PET brain scans is glucose modified to contain radioactive fluorine atoms. Our molecular inset shows a simplified model of this modified glucose molecule. 

Xiao, B., Tu, J. C., and Worley, P. F., Homer a link between neural activity and glutamate receptor function, Curr. Opin. Neurobiol., 10(3), 370-374, 2000. 

FIGURE 5-14 Spatial buffering by astrocytes. This conceptual diagram indicates the pathways available for potassium ions to diffuse through the glial syncytium (light red) subsequent to their release from neuronal membranes (dark red) during neural activity. 

Fox, P. T., Raichle, M. E., Mintun, M. A. etal. Nonoxidative glucose consumption during focal physiologic neural activity. Science 241 462-464,1988. 

This chapter focuses on the neurochemical and molecular aspects of the influences of hormones on the nervous system and behavior, after first considering the chemical signals, behavioral events and underlying neural activity that regulate hormonal secretion. 

Regarding the adrenal steroids, the behavioral activation of hormonal secretion in stress is part of a mechanism for restoring homeostatic balance. For example, an encounter with a predator may require rapid evasive action, in which neural activity and rapidly mobilized hormones such as epinephrine play a role. Adrenal steroid secretion is slower, reaching a peak minutes after the stressful event, and therefore is not expected to play a role in coping with the immediate situation. If the evasive action is successful and... 

These 49 words have formed what now is known as Hebb s Learning Rule. Although some minor modifications have been required over the years, the essence of Hebb s rule remains unchanged a memory is produced by coincident neural activity when two connected nerve cells are active simultaneously, the strength of their synaptic connection increases this confers a basis for the persistence of memory. 

Electroencephalography allows real-time measurement of neural activity with millisecond temporal resolution. When coupled with the repeated presentation of a stimulus, the electroencephalograms can be averaged to produce an event-related potential (ERP), whose components develop and resolve within tens or hundreds of milliseconds. These potentials are designated by the millisecond lag between presentation of the stimulus and the appearance of the ERP, with the P50 (i.e. potential at 50 ms after... 

An important methodologic point about the majority of these studies is that they use a reduced preparation, in which the spinal cord is neurally isolated from the brain by a complete transection (129). The rationale for using this simplified preparation is that spinal reflex activity can be analyzed in the absence of supraspinal influences. However, transection may introduce other variables (i.e., ischemia, disruption of the blood-brain barrier, loss of tonic neural activity from supraspinal systems), which may result in drug effects on spinal reflexes that are quantitatively or even qualitatively different than those seen in the intact animal. Thus the following review of hallucinogen effects on spinal reflexes is organized into two main categories (a) studies in transected animals, and (b) those in decerebrate or intact preparations. 

Pioneering efforts to understand the nature of olfactory coding were reported by Adrian (24-27). His work introduced the ideas that different odors activate ORCs in different regions of the olfactory epithelium and that spatiotemporal patterns of ORC firing would suffice to encode different odors. Subsequent studies by many investigators and involving various recording methods (reviewed in refs. 13 and 28) led to the conclusion that, at various levels of the pathway, the olfactory system uses distributed neural activity to encode information about olfactory stimuli. 

Baraban, S.C., Taylor, M.R., Castro, P.A., and Baier, H., Pentylenetetrazole induced changes in zebrafish behavior, neural activity and c-fos expression, Neuroscience, 131, 759-768, 2005. 

Some functional neuroimaging studies have examined the effects of scopolamine in cognitive tasks. Although scopolamine inhibits increases in cerebral blood flow to somatosensory stimulation, it does not inhibit the neural response (Ogawa et al. 1994). Thus, cholinergic systems may be involved in coordination of cerebral blood flow increases to neural activation. Subjects performing an attentional auditory discrimination... 

Fig. 2 Neural activation in responses to smoking (vs, neutral) cues, showing the effects of expectancy to smoke and by abstinence states. Overall, the network of brain regions recruited by smoking-related cues was affected only slightly by abstinence, but was affected dramatically by expectancy, with greater activation observed when participants believed they would be allowed to smoke after the scan (top) (McBride et al. 2006)...

Table 4 Neural activation associated with sustained attention and working memory... 

Lawrence et al, (2002) 15 14 4.5 4.7 RVIP In smokers, nicotine improved task performance and increased neural activity in the parietal and occipital cortices, the thalamus and caudate, and decreased activity in left frontal, anterior and posterior cingulate, insula, and left parahippocampal regions. 

Xu et al. (2005) 8 NA 4.1 14.4 N-Back Task-related neural activity in the left DLPFC showed a significant interaction between test session working memory load. When smokers had smoked ad libitum, task-related activity in the left dorsolateral prefrontal cortex was relatively low for an easy task condition (1-back), and increased as task difficulty increased but when smokers were abstinent overnight, activity in the L-DLPFC was approximately as high at low task level as it was at more difficult levels. 

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