Brain frontal

Textbooks on neuroscience often describe the location and function of hundreds of individual brain regions (see references above). However, for current purposes these will be kept to a minimum (Figure 2.1). Anatomically, the brain can be subdivided into the forebrain containing the telencephalon and diencephalon, the midbrain or mesencephalon and the hindbrain (metencephalon and myelencephalon). The telencephalon includes the left and right cerebral hemispheres encompassed by the cerebral cortex (neocortex). Cortex is a translation of the word bark and is so-called because its surface, made up of numerous sulci (grooves or invaginations) and gyri (raised areas), is on the outer surface of the brain like the bark of a tree. Each hemisphere is divided into four lobes, named from the front (rostral) to back (caudal) of the brain frontal, temporal, parietal and occipital. 

In REM sleep we see this reciprocity at the brain function level. The emotional brain (amygdala) is hyperactive. The executive brain (frontal cortex) is hypoactive. Result emotion is in the saddle. Rational thought is struggling—and failing—to get control of the runaway horse that is the dream. "Don t lose your temper, you say to yourself. This mantra says it all. If you can t maintain top-down control, your emotional brain will get the better of you. 

Ki values for human brain frontal lobe sites labelled by [ H]-mepyramine... 

Fluvoxamine and clovoxamine are nontricyclic monoamine uptake inhibitors structurally related to the tricyclic smtidepressant noxiptiline (fig. 3). Both fluvoxamine and dovoxamine are trans isomers. Clovoxamine is a potent but nonselective inhibitor of the 5-HT and NE transporter in a synaptosomal preparation of the rat brain frontal cortex (Kj=5.9 and 7.0 nM respectively) and a weak (KjS 720 nM) inhibitor of the DA transporter in synaptosomes of the corpus striatum [26]. 

Positron emission tomography studies using "C-toluene in nonhuman primates and mice showed a rapid uptake of radioactivity into striatal and frontal brain regions (Gerasimov et al. 2002). Maximal uptake of the radiotracer by these structures occurred 1 minutes after intravenous administration. Subsequently, clearance of the radiotracer from the striatal and frontal areas occurred rapidly, with a clearance half-life from peak uptake of 10—20 minutes. Radiotracer clearance from white matter appears to be slower... 

Many brain areas are innervated by neurons projecting from both the locus coeruleus and the lateral tegmental system but there are exceptions (Fig. 8.3). The frontal cortex, hippocampus and olfactory bulb seem to be innervated entirely by neurons with cell bodies in the locus coeruleus whereas most hypothalamic nuclei are innervated almost exclusively by neurons projecting from the lateral tegmental system. The paraventricular nucleus (and possibly the suprachiasmatic nucleus, also) is an exception and receives an innervation from both systems. 

Figure 8.11 Noradrenaline efflux, measured by microdialysis, in the rat frontal cortex and hypothalamus, (a) Repeated exposure to a tone, alone, has no effect on noradrenaline efflux in either brain region, (b) After repeated pairing of the tone with transfer of the rat to a brightly lit (aversive) arena, the sound of the tone alone triggers a significant ( P<0.05, cf last basal sample) increase in noradrenaline efflux in the frontal cortex, but not the hypothalamus. (Based on a figure from McQuade and Stanford 2000)...

PAN Y, ANTHONY M, CLARKSON T B (1999b) Evidence for up-regulation of brain-derived neurotrophic factor mRNA by soy phytoestrogens in the frontal cortex of retired breeder female rats. Neurosci Lett. 261 17-20. 

Ryan, L.J. Tepper, J.M. Young, S.J. and Groves, P.M. Frontal cortex stimulation evoked neostriatal potentials in rats Intraeellular and extraeellular analysis. Brain Res Bull 17 751-758, 1986a. 

Mesocortical A neural pathway that connects the ventral tegmentum to the cortex, particularly the frontal lobes. It is one of the major dopamine pathways in the brain. 

Arora, R. C. Meltzer, H. Y. (1989). Serotonergic measures in the brains of suicide victims 5-HT(2) binding sites in the frontal cortex of suicide victims and control subjects. Am. J. Psychiatry, 146, 730-6. 

Figure 6.2 Frontal section of the brain. The cerebrum is composed of two types of tissue internal white matter and external gray matter which forms the cerebral cortex. Embedded within the cerebral hemispheres are other masses of gray matter, basal ganglia, and thalamus. The ventricles are filled with cerebrospinal fluid (CSF).

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