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The Reticular Formation– the The Reticular Formation– the “connection”“connection”
This formation regulates brain This formation regulates brain activity reaching the cerebral activity reaching the cerebral cortex by way of the thalamus.cortex by way of the thalamus.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
The reticular formation consists of The reticular formation consists of three columns of organized nuclei three columns of organized nuclei extending from the upper limits of extending from the upper limits of the spinal cord to the thalamus.the spinal cord to the thalamus.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
It receives all of the peripheral It receives all of the peripheral ascending afferent sensory ascending afferent sensory information. information.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
Its organization is so efficient, that Its organization is so efficient, that a single neuron is capable of a single neuron is capable of activating large areas of the activating large areas of the thalamus and, in turn, the cerebral thalamus and, in turn, the cerebral cortex.cortex.
One of its neurons can excite up to One of its neurons can excite up to 25,000 other neurons.25,000 other neurons.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
•ConsciousnessConsciousness
It is a vital contributor to our It is a vital contributor to our conscious system. Based upon conscious system. Based upon the sensory information the sensory information received, it regulates how “alert” received, it regulates how “alert” we are. we are.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
• ConsciousnessConsciousness
Based upon the information it receives Based upon the information it receives (both efferently from the brain and (both efferently from the brain and afferently from the peripheral system) it afferently from the peripheral system) it elevates the degree of brain activity.elevates the degree of brain activity.
Similar to the operator of an Similar to the operator of an automobile.automobile.
(steering, braking, accelerating)(steering, braking, accelerating)
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
•Consciousness/AlertConsciousness/Alert
During the awake state of a human, During the awake state of a human, sensory information from both the sensory information from both the internal body stimulus and the internal body stimulus and the external environment is projected to external environment is projected to the thalamus.the thalamus.
This contributes to alert behavior. This contributes to alert behavior.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
• Consciousness/SleepConsciousness/Sleep
As input to the brain is diminished, the As input to the brain is diminished, the level of consciousness decreases until level of consciousness decreases until the level of sleep is reached. the level of sleep is reached.
Sleep is not a state of unconsciousness.Sleep is not a state of unconsciousness.
The body is sleeping but the brain is The body is sleeping but the brain is awake.awake.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
• Consciousness/SleepConsciousness/Sleep
This sleep condition can be quickly This sleep condition can be quickly reversed by the reticular system—reversed by the reticular system—usually after about eight hours.usually after about eight hours.
Various internal body functions and Various internal body functions and external environmental stimuli external environmental stimuli occur.occur.
The Reticular Formation– the The Reticular Formation– the “connection”“connection”
It receives information from a It receives information from a variety of sources—from the variety of sources—from the efferent motor senses of the brain, efferent motor senses of the brain, to the peripheral sensory nerves.to the peripheral sensory nerves.
One of its most vital sources of One of its most vital sources of “decision making” stimulus is from “decision making” stimulus is from the eighth nerve—it never sleeps!the eighth nerve—it never sleeps!
