Reticular Formation Notes

Lecture 46

Reticular Formation

• Location

  • Midbrain- Mesencephalic RF (neurons scattered around here)

  • Pons- Pontine RF (adjacent to 4^th ventricle)

  • Medulla- Medullary RF

• Afferent/Efferent

  • Afferent

    • Sensory pathways (optic, auditory, olfactory)

    • Thalamus

    • Cerebellum

    • Corpus striatum

    • SC (touch, pain, temperature)

    • Cortex

  • Efferent

    • Cortex (main)

    • Cerebellum

    • Substantia nigra; Red nucleus

    • Tectum

    • SC

    • Thalamus/hypothalamus

• Connections

  • Local projections

    • Local-circuit interneurons

    • Functions

      • Reflexice and stereotyped behaviours of head and face

        • Chewing, swallowing, vomiting

        • Respiratory (coughing, hiccups, sneezing)

        • CVS responses (heart rate, BP)

  • Long projection systems

    • Ascending to cortex (reticular activating system)

      • Functions

        • Sleep-wake cycle

        • Alertness and consciousness

        • Wakefulness

    • Descending to spinal cord

      • Functions

        • Posture and ANS activity

        • Sensory (pain) & motor modulation (target for anaesthetics)

        • Info from hypothalamus (connected to endocrine systems)

• Functions

  • SENSORY & MOTOR FUNCTIONS

    • Gating and modulating info transfer

    • Organising, co-ordinating and regulating reflexes

    • Reticulospinal tracts

  • AUTONOMIC AND VITAL FUNCTIONS

    • Regulations of ANS (input on everything innervated by ANS)

    • CVS regulation

    • Control respiration

• Neurotransmitter systems

  • Specific group of CNS neurons use monoamines and ACh as neurotransmitters

    • NA; A; DA; 5HT; Histamine= MA

    • ACh

  • Cell bodies can be localised and axons traced

  • Monoamine pathways (where cell bodies lie)

    • Lateral Tegmental system

      • To the hypothalamus, cord and BG

      • Function= autonomic, endocrine, eating

      • NA

    • Locus ceruleus

      • To cerebellum, thalamus, cerebral cortex & cord

      • Function= aletness, attention

      • NA

    • Raphe

      • To cerebellum, BG, Th, cerebral cortex and cord

      • Function= Sleep, mood/motivation, autonomic, pain

      • 5HT

    • Sunstantia Nigra & Ventral Tegmental Area

      • To pituitary, nucleus accumbens, frontal cortex & limbic system, BG

      • Function= Drive/motivation, pleasure

      • Loss= PD

      • DA

  • Acetylcholine pathways

    • Basal Forebrain Nucleus & Septal Nuclei and Septal Nuclei to Hippocampus

      • To cortex, Th

      • Function= Alertness/sleep, memory

      • ACh

• Functions of reticular formation

  • CVS

    • Organised in medullary and lower pontine reticular formation

    • Control (blood pressure, heart rate)

      • Inputs

        • Baro/Chemoreceptors; Vagus; Cord; PAG; Hypothalamus; Cerebellum

        • Nerves IX, X

      • Output

        • Dorsal motor nucleus vagus; Intermediolateral column in cord (SNS)

        • Nerve X

  • Generation of ventilator pattern

    • Integration of neural signals by respiratory control centres in medulla & pons

      • Medulla (reticular formation)

        • Ventral respiratory group (forced exhalation, increased insp.)

        • Dorsal resp. group/Nucleus tractus solitairius...

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