Cerebrum

The brain is the integrative portion of the nervous system that serves to receive, process, and store sensory information and then plan and orchestrate the appropriate motor response. It is divided into several anatomically and functionally distinct regions (see Table 6.2). The forebrain consists of the cerebrum, basal ganglia, thalamus, and hypothalamus. The midbrain, along with the pons and the medulla of the hindbrain, composes the functional region referred to as the brainstem. The cerebellum is also considered a component of the hindbrain but is functionally distinct from the brainstem. 

The gray matter, which contains the cell bodies of neurons, is on the outer surface of the cerebrum and forms the cerebral cortex. The white matter, composed of the myelinated axons of neurons, is found underlying the cortex in the core of the cerebrum. These axons are bundled together according to function and organized into units referred to as tracts. The three types of tracts in the cerebrum are  

Both hemispheres of the cerebrum consist of four lobes, including  

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Gross-him, n. cerebrum- -himrinde,/. cerebral cortex. -Industrie,/. = Grossgewerbe. grossl hrig, a. of age. 

The barbiturates are effective against convulsions induced experimentally from all central locations, the cerebrum, medulla, or spinal cord. They may be used clinically as well as experimentally to suppress most, if not all, varieties of convulsions of central origin (3). Since they are effective in the prevention of the tremors, tonic and clonic convulsions, and in the restoration of normal respiration from the Cheyne-Stokes type, produced by chlordan, it appears that these symptoms may have their origin in the central nervous system. 

Cerebrum and cerebral Processes, integrates, and analyzes information... 

The spinal cord is the most anatomically inferior portion of the CNS and its functions are at the lowest level of sophistication (see Table 6.1). As mentioned earlier, the spinal cord receives sensory input from the periphery of the body and contains the cell bodies of motor neurons responsible for voluntary and involuntary movements. Once again, the involuntary and neurologically simple reflexes are processed entirely at the level of the spinal cord. Voluntary, deliberate movements are initiated and controlled by thought processes in the cerebrum. The second important function of the spinal cord is to transmit nerve impulses to and from the brain. Ascending pathways carry sensory input to higher levels of the CNS and descending pathways carry impulses from the brain to motor neurons in the spinal cord. 

The cerebrum is composed of two hemispheres, left and right, that are anatomically connected to ensure communication between them. Two types of tissue compose each hemisphere (see Figure 6.2) ... 

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).

Named for the bones of the cranium under which they lie, the lobes are conspicuously defined by prominent sulci of the cortex, which have a relatively constant position in human brains. Each lobe is specialized for different activities (see Figure 6.3). Located in the anterior portions of the hemispheres, the frontal lobes are responsible for voluntary motor activity, speaking ability, and higher intellectual activities. The parietal lobes, which are posterior to the frontal lobes, process and integrate sensory information. The occipital lobes, located in the posterior-most aspects of the cerebrum, process visual information, and the temporal lobes, located laterally, process auditory information. 

The gray matter is composed of nerve cell bodies and unmyelinated intemeuron fibers. The location of the gray matter in the spinal cord is opposite to that of the brain. In the brain, the gray matter of the cerebrum and the cerebellum is found externally forming a cortex, or covering, over the internally located white matter. In the spinal cord, the gray matter is found internally and is surrounded by the white matter. 

FIGURE 14.3 (a) Achiral separation of NBD-alanine in the rat cerebrum, (b) The chiral... 

Fig. 9.4 Evolutionary change in the zones of vertebrate brains. Note that the figures are related here to the cerebrum cortex so that in man the hindbrain appears twisted downwards to allow for human upright stance.

Fig. 9.5 A midsagittal section through the human brain. Note that in this type of section half of the brain is cut away so that structures normally covered by the cerebrum are exposed.

In Forest Steppe biogeochemical province with Eutric Phaerozems and Distric Chernozems, enriched in all trace metals, such illnesses as lung and stomach cancer, tumor of cerebrum and spinal cord, and nephritis are predominant, whereas the Addison-Bearmer anemia, progressive myopia and glaucoma are relatively seldom. 

It may be noted that the retina represents an outlying portion of the brain itself. It arises as a protrusion from the prosencephalon (anterior portion of the cerebrum), and, being a constituent part of the brain, presents the same anatomical and physiological problems as does the central nervous system elsewhere. The more or less complete spatial separation of the synapses from the cell bodies makes the retina eminently suitable for finding out whether a known biochemical constituent is located in the cell bodies, axons, dendrites or at the synapses, and the information so obtained may perhaps be applicable to other parts of the nervous system, where the cell bodies and the synapses are all too intimately mingled for a proper analysis. 

Cerebrovascular Pertaining to the blood vessels of the cerebrum, or brain. [EU]... 

Cerebrospinal fluid is produced in chambers within the brain called ventricles. Two lateral ventricles and a midline third ventricle are contained within the cerebrum, while the fourth ventricle exists within the brain stem. CSF is produced by the choroid plexus in the lateral and third ventricles. It flows out through the ventricles by a series of aqueducts and into subarachnoid space. CSF supports the brain and spinal cord, ab-... 

The cerebrum is composed of four lobes covered by cerebral cortex frontal, parietal, temporal, and occipital (figure 2.9). The cortical surface... 

CYPl 1B2 mRNA in rat hypothalamus, hippocampus, amygdala, cerebrum, and cerebellum by RT-PCR and Southern blot (Gomez-Sanchez et al., 1997). 

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