PSYCH 454 Lecture Notes - Lecture 22: Isoflurane, Propofol, Light Stage
24 May 2018
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Lect 22: Consciousness
What is consciousness?
●(Loose definition) Consciousness: awake state in which we have experiences that we are
able to report
●How can i tell if someone else is conscious?
○Monitor behaviors and their reported
experiences
○Do they behave like me?
○How can i tell if someone is conscious if their paralyzed? → may have awareness
experience, but unable to report physically so you would have record brain
activity and agree upon signatures of consciousness
●Machine conscious?
○Do they behave like humans
○Turing test: can the machine be distinguished from a human? → asks specific
questions, can you differentiate the two response? No easy answer
●Animal conscious?
○Mirror self recognition test: does subject respond to red dot placed on forehead
when looking @ self in mirror? (issues with this test → assuming all animals
know how mirrors work)
■Chimpanzees = pass the test
○Most mammals fail (ex:dogs) → does this mean their not conscious?
Loss of consciousness
●Sleep: involves cycles throughout night; @ start → light stage sleep (stage 1); as you
progress, deeper states (stage 4)
○Non-REM sleep (stages 1-4)
■@ start of sleep= dominates
○REM sleep→ closer to the level of consciousness
●General anesthesia:
○Caused by a number of drugs with different molecular mechanisms of action
(many different types of systems can lead to loss of consciousness)
■Ex: ketamine → NMDA (glutamate) receptor antagonist
●Sensory disconnection → different non-conscious state
■Ex: isoflurane→ inhibits voltage-sensitive Na channels
■Ex: propofol→ increases GABA-A receptor effects
●Influence inhibitory transmission of brain
■Each drug has different targets, but all give rise to loss of consciousness
●Disorders of consciousness
○Brain Stem death, coma, persistent vegetative state, minimally conscious state
Document Summary
(loose definition) consciousness: awake state in which we have experiences that we are. How can i tell if someone else is conscious? able to report. May have awareness experience, but unable to report physically so you would have record brain activity and agree upon signatures of consciousness. Mirror self recognition test : does subject respond to red dot placed on forehead when looking @ self in mirror? (issues with this test assuming all animals know how mirrors work) Sleep: involves cycles throughout night; @ start light stage sleep (stage 1); as you progress, deeper states (stage 4) Rem sleep closer to the level of consciousness. Caused by a number of drugs with different molecular mechanisms of action (many different types of systems can lead to loss of consciousness) Ex: ketamine nmda (glutamate) receptor antagonist. Each drug has different targets, but all give rise to loss of consciousness. Brain stem death, coma, persistent vegetative state, minimally conscious state.
