Limbic System
• Limbic SystemThe word “limbic” means “border.”
It means the border structures around the basal regions of the cerebrum
the functions of the limbic system, controls and supports a variety of functions including emotional behavior and motivational drives, long-term memory, fear, searching for food or drinking water , olfaction and other functions
A major parts of the limbic system are the cortical and subcortical structures
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limbic cortex Surrounding the subcortical limbic structures It is composed of a ring of cerebral cortex in each side of the brain (1) beginning in the orbitofrontal area is the portion over the orbits , (2) extending upward into the subcallosal gyrus, (3) then in the cingulate gyrus, and finally (4) to the parahippocampal gyrus and uncus.
• subcortical structures includes hypothalamus, the septum, the araolfactory area, the anterior nucleus of the thalamus, portions of the basal ganglia, the hippocampus, and the amygdala.
Thalamus
Function of the thalamusThalamus functions as sensory relay station, also play important role in emotions ,memory.
Hypothalamus its very small sizeAbove the pituitary gland and below the thalamusIn addition to their roles in behavioral control, these areas control many internal conditions of the body
send output signals in three directions(1) downward to the reticular formation of the brain stem from these areas into the peripheral nerves of the autonomic nervous system (2) upward to the thalamus and limbic cortex(3) to the hypothalamic infundibulum to control the posterior and the anterior pituitary glands by triggering the release of hormones.Also control body temperature, osmolality of the body fluids, and the drives to eat and drink
The Hippocampus
The hippocampus has numerous connections with the cerebral cortex as well as with the basal structures of the limbic system.Stimulation of the hippocampus can cause different behavioral patterns such as pleasure, anger
hippocampus is critically involved in memory.
The Amygdala
It is a complex of multiple small nuclei located in the anterior pole of each temporal lobe. with the hypothalamus and the other areas of the limbic system
the Amygdala concern with the fear and anxiety
Mental or physical stress can excite the sympathetic system, this is called the sympathetic stress response or alarm reaction. It is also called the fight or flight reaction.
Stimulation of the amygdala is believed to make the person’s behavioral response appropriate for each occasion
• Function of the Limbic Cortex
The most poorly understood portion of the limbic system is the limbic cortex that surrounds the subcortical limbic structures. the limbic cortex in effect functions as a cerebral association area for control of behaviorcingulate gyrus, responsible for satisfaction