The brain is the apparatus that is responsible for the dynamic of the levels. It carries out this work with diverse components, the most noteworthy of which are the following:
Sensitive Pathway (Classic). A nerve bundle that ascends along the stem, carrying sensory impulses directly to the Cortex. During its ascent it branches out toward the cerebellum and the FRF, which process the information, distributing it in the sub-cortex before sending it, via the thalamus, also to the cortex.
Brain Stem. Connects the spinal cord (collector of impulses from the entire organism) to the brain, which in turn is connected to the cerebellum. Anatomically contains the reticular formation and, functionally, the centers that regulate vegetative functions such as heartbeat, breathing and digestion.
Firing Reticular Formation (FRF). Does not constitute an anatomical unit, but rather a mass of tissue formed by a fine network of fibers and neurons of structures that are very different amongst themselves. They are located longitudinally in the center of the stem and in the midbrain. All the fibers that come from the senses go through the FRF, which in turn connects with all the parts of the subcortex (via the hypothalamus) and the cortex (via the thalamus). Analyzes and assesses sensory information. In combination with the other subcortical centers, it transmits “nonspecific” (sensory) impulses, which modify the reactivity of the cortex. From our interest, it appears as the center of gravity of the alternating circuit of the levels of consciousness.
Hypothalamus. Located above the stem, it is a nervous-endocrine nucleus connected to the cortex through the thalamus and to the hypophysis through numerous capillaries and nerve fibers. With these last, a structure of neurohormonal interstimulation is formed,through which the hypothalamus integrates and coordinates diverse autonomous vegetative functions conjointly with the entire hormonal system. In itself it coordinates the information (especially cenesthetic information) among the different encephalic zones.
Hypophysis. Endocrine gland composed of an anterior pituitary lobe, an intermediary part (both made of glandular tissue) and a posterior lobe (of nervous tissue), each performing different functions. It is stimulated and regulated by hypothalamic hormones. Through the hypothalamus (feedback), it connects with the cerebrum and the nervous system in general. On the other hand, it regulates and controls the entire hormonal system through the blood (and more specifically, stimulates the thyroid, gonads and suprarenals, and such functions as growth, diuresis and vascular pressure, among others).
Thalamus. This is a transmitter of information coming from the cortex and sub-cortex. A center of control and integration of impulses, and re-elevator of tension
Limbic System. Old system of nervous regions located in the subcortex, seat of the emotion al functions and of vital functions such as nutrition,, the vegetative function in general and, in part, the sexual function. This structure of emotion al-vegetative functions is the explanation for psychosomasis. It includes the hypothalamus, aside from other structures of importance.
Cortex. The most external brain layer (two millimeters thick) or grey matter (neuronal bodies). Controls the limbic center, sensation and movement in general (motor localization) and is the base of the “superior or thinking functions” (intellectual) given by multi-related localizations of response control and coordination, based on the recovery of present sensorial and memory information.
The subcortex encompasses the limbic system, hypothalamus, thalamus and midbrain. The white matter is a mass of connective fibers (axons) between the subcortex and the cortex (gray matter).