Reticular Formation
A series of long slim nerve tracts positioned in much of the length of the brain
stem. The reticular formation detects incoming sensory information from many sources
and passes activating signals up through the midbrain to regions of the cerebral
cortex. It is a part of the brain that is involved in actions such as:
- The awaking - sleeping cycle.
- Filtering incoming stimuli to discriminate irrelevant background stimuli. [1]
The reticular formation consists of more than 100 small neural networks, with varied
functions such as:
Somatic motor control - Some motor neurons send their axons to the reticular formation
nuclei, giving rise to the reticulospinal tracts of the spinal cord. These tracts
function in maintaining:
- Tone.
- Balance.
- Posture (especially during body movements).
The reticular formation relays eye and ear signals to the cerebellum so that the
cerebellum can integrate visual, auditory, and vestibular stimuli in motor coordination.
Other motor nuclei include:
- Gaze centres, which enable the eyes to track and fixate objects.
- Central pattern generators, which produce rhythmic signals to the muscles of breathing
and swallowing.
Cardiovascular control - The reticular formation includes the cardiac and vasomotor
centres of the medulla oblongata.
Pain modulation - The reticular formation is one means by which pain signals from
the lower body reach the cerebral cortex. It is also the origin of the descending
analgesic pathways. The nerve fibres in these pathways act in the spinal cord to
block the transmission of some pain signals to the brain.
Sleep and consciousness - The reticular formation has projections to the thalamus
and cerebral cortex that allow it to exert some control over which sensory signals
reach the cerebrum and come to our conscious attention. It plays a central role in
states of consciousness like alertness and sleep.
Habituation - The process in which the brain learns to ignore repetitive, meaningless
stimuli while remaining sensitive to others.
[2] [3]
1. thebrain.mcgill
2. biology.about.com
3. wapedia.mobi
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