The reticular formation is a region in the brainstem that regulates consciousness and brain activity. It consists of three columns of nuclei extending from the spinal cord to the thalamus. The reticular formation receives all peripheral sensory information and is capable of activating large areas of the thalamus and cortex. It regulates levels of alertness and consciousness based on sensory information received, elevating brain activity during wakefulness and allowing sleep when input is diminished.

1. The Reticular Formation– the “connection”
This formation regulates brain activity
reaching the cerebral cortex by way
of the thalamus.

2. The Reticular Formation– the “connection”
The reticular formation consists of three
columns of organized nuclei extending
from the upper limits of the spinal cord to
the thalamus.

3. The Reticular Formation– the “connection”
It receives all of the peripheral
ascending afferent sensory
information.

4. The Reticular Formation– the “connection”
Its organization is so efficient, that a
single neuron is capable of activating
large areas of the thalamus and, in
turn, the cerebral cortex.
One of its neurons can excite up to
25,000 other neurons.

5. The Reticular Formation– the “connection”
• Consciousness
It is a vital contributor to our
conscious system. Based upon the
sensory information received, it
regulates how “alert” we are.

6. The Reticular Formation– the “connection”
• Consciousness
Based upon the information it receives
(both efferently from the brain and
afferently from the peripheral system) it
elevates the degree of brain activity.
Similar to the operator of an automobile.
(steering, braking, accelerating)

7. The Reticular Formation– the “connection”
• Consciousness/Alert
During the awake state of a human,
sensory information from both the internal
body stimulus and the external
environment is projected to the thalamus.
This contributes to alert behavior.

8. The Reticular Formation– the “connection”
• Consciousness/Sleep
As input to the brain is diminished, the
level of consciousness decreases until the
level of sleep is reached.
Sleep is not a state of unconsciousness.
The body is sleeping but the brain is
awake.

9. The Reticular Formation– the “connection”
• Consciousness/Sleep
This sleep condition can be quickly
reversed by the reticular system—
usually after about eight hours.
Various internal body functions and
external environmental stimuli occur.

10. The Reticular Formation– the “connection”
It receives information from a variety
of sources—from the efferent motor
senses of the brain, to the peripheral
sensory nerves.
One of its most vital sources of
“decision making” stimulus is from the
eighth nerve—it never sleeps!