Consciousness & the Reticular Formation

• What is the reticular formation?

  Complex matrix of neurons in the brainstem
• Where does the reticular formation project to?

  Into the cerebral hemispheres and spinal cord
• What are some well-defined nuclei in the reticular formation?

  Respiratory and cardiac centres
• What is the source of input to the reticular formation?

  All parts of the CNS
• Which structures provide influential input to the reticular formation?

  Spinal cord, cranial nerves, cerebellum, forebrain
• What type of outputs does the reticular formation have?

  Connections to virtually all brainstem nuclei
• What are the basic functions of the reticular formation?

  Sleep, consciousness, motor control, cardiovascular control
• What is the role of the ascending reticular activating system?

  Influences mood, learning, memory, and arousal
• What are the four groups of nuclei in the ascending activating system?

  Locus coeruleus, raphe nucleus, VTA, basal forebrain
• What functions are associated with the locus coeruleus?

  Attention, arousal, sleep-wake cycle, mood
• What neurotransmitter is associated with the locus coeruleus?

  Noradrenaline
• What functions are associated with the raphe nucleus?

  Sleep-wake, mood control, emotional behavior
• What neurotransmitter is associated with the raphe nucleus?

  Serotonin
• What are the functions of the ventral tegmental area (VTA)?

  Reward behavior, attention, mood
• What pathways are linked to the VTA?

  Mesolimbic and mesocortical pathways
• What is the role of acetylcholine in the basal forebrain?

  Linked to memory and learning
• What is the primary regulator of REM sleep?

  Pontine reticular formation
• What is the function of the medial reticulospinal tract?

  Enhances antigravity reflexes
• What does the lateral reticulospinal tract do?

  Liberates antigravity muscles from reflex control
• What are the collective functions of reticulospinal fibres?

  • Modulate muscle tone
  • Regulate posture
  • Participate in automatic reflexes
• What are the key functions of the reticular formation?

  • Sleep and consciousness
  • Somatic motor control
  • Cardiovascular control
  • Pain modulation
• What are the main components of the ascending reticular activating system?

  • Locus coeruleus
  • Raphe nucleus
  • Ventral tegmental area
  • Basal forebrain
• What are the effects of degeneration of acetylcholine neurons?

  • Linked to Alzheimer's disease
  • Impacts memory and learning
• What is the relationship between serotonin levels and mood?

  • Low levels associated with depression
  • SSRIs prevent serotonin reuptake
• What is conciousness?

  Awareness of self and surroundings with the ability to react to these
• What is reduced/altered consciousness?

  Partial/complete loss of awareness of self/surroundings OR the inability to react to them
• What is unconsciousness?

  Global dysfunction of the brain (that is not sleep)
• What two things does consciousness require?

  Wakefulness & awareness
• What is wakefulness?

  A state in which the eyes are open and there is a degree of motor arousal/response
• What is awareness?

  The ability to have an experience of any kind. Knowledge and understanding of things happening. Complex thought processes.
• What is the definition of coma?

  Absent wakefulness and awareness
• What characterizes unrousable unresponsiveness in coma?

  The patient cannot be awakened
• How long must a coma last to be classified as such?

  More than 6 hours
• What does it mean if a patient lacks a normal sleep-wake cycle in coma?

  The patient does not exhibit sleep patterns
• How does a patient in a coma respond to painful stimuli?

  Fails to respond normally
• What is Unresponsive Wakefulness Syndrome (UWS)?

  Wakefulness but absent awareness
• What is another name for Unresponsive Wakefulness Syndrome?

  Vegetative state
• What does it mean when a patient shows no awareness in UWS?

  No recognition of self or environment
• What signs indicate a patient is awake in UWS?

  Spontaneous or stimulus-induced response
• What is a characteristic of the sleep-wake cycle in UWS?

  The patient exhibits a sleep-wake cycle