8.2.1 Consciousness Flashcards
What is consciousness?
Awareness of both external world and internal states
What is arousal?
Emotional state associated with a goal or avoidance of something noxious
What neural components are required for consciousness?
Cerebral cortex
Reticular formation
What is the function of the cerebral cortex in conciousness?
Site where conscious thoughts arise, receives many inputs, including from reticular formation
What is the function of the reticular formation?
Keeps the cortex awake, receives many inputs, including from the cortex and sensory systems
How are the cerebral cortex and reticular formation connected?
Connected by reciprocal excitatory projections
Forms a positive feedback loop, seen when there is a binary outcome e.g. sleep/awake, ovulating/not ovulating
What are the 3 major relay nuclei from the reticular formation to the cortex?
Basal forebrain nuclei
Hypothalamus
Thalamus
What type of projections does the reticular formation send to the cerebral cortex?
Cholinergic, excitatory projections
Outline the Basal forebrain nuclei projections
First order sensory neurones synapse with second order
Second order decussate and arise to the reticular formation
Reticular formation sends projections to the basal forebrain nuclei
Basal forebrain nuclei send ACh excitatory projections to the cortex
Outline the Hypothalamus excitatory fibre projection to the cortex
First order sensory neurones synapse with second order
Second order decussate and arise to the reticular formation
Reticular formation sends projections to the Hypothalamus
Hypothalamus sends histaminergic excitatory projections to the cortex
Hence why anti-histamines have a sedative effect
Outline the Thalamus excitatory fibre projection to the cortex
First order sensory neurones synapse with second order
Second order decussate and arise to the reticular formation
Reticular formation sends projections to the Thalamus
Thalamus sends glutamatergic excitatory projections to the cortex
Where else does the reticular formation also send projections?
Down the cord, responsible for maintaining muscle tone
What is the reticular activating system?
Large part of the reticular formation devoted to arousal
Contains the fibre projections from the reticular formation to the basal forebrain, hypothalamus and thalamus
How is consciousness assessed?
Glasgow coma scale
What are the 3 parts used by the GCS to assess conciousness?
Eyes- 4(eyes 4 letters so 4)
Motor response- 6(muscle 6 letters so 6)
Verbal response- 5 (voice 5 letters so 5)
Score out of 15 (higher the better)