Lecture 15: Neural Mechanisms for
Consciousness
Neural Correlates of Consciousness
The problems with identifying a neural correlate/substrate is under defined is because of the word
‘consciousness’ – hard to know what question we are asking
Various meanings of consciousness
Aspects of consciousness
• Wakeful vs inanimate state – whether you are up and walking around and engaging in
behaviour – most critical in a clinical setting
o In everyday life you go through an ordinary sleep between consciousness and
unconsciousness (sleep)
o Dream could be considered its own sense of consciousness
o Anaesthesia – deliberate depression of consciousness, or for the purpose of
vaoiding pain
o A minimally conscious (vegetative)state as a result of a brain injury – used to be
classified on the basis of outward symptoms, but locked-in syndrome (outward
impression of unconsciousness, but aware internally)
§ How much does overt behaviour actually tell us about someone’s state
of consciousness? – Often not nearly as much as we think it should
§ There has been a lot of research to come up with assessing someone’s
subjective state of consciousness (that relies on other measurable
variables)
• Awareness
o Conscious vs unconscious processing
§ Your day is not just considered by careful conscious consideration but
routines, habits, reflexes and cognitive biases (unconscious processing)
o Attention vs inattention (Psychology gorilla experiment) Commented [IM292]: Count how many passes / order the
students made
§ Many stimuli are detected by our nervous system that never reaches our -Paid so much attention to that to do the task, most subjects
conscious awareness – because our attention is focused elsewhere didn’t notice a guy in the gorilla suit walking directly
thorugh the frame
-Most subjects had no recall of the guy in the gorilla suit
Therefore, even when you are globally conscious generally the specific content of your
consciousness is constrained Conclusion: Attention counts quite a bit with regards to the
content of our conciousness
• Unity – any intuitive sense of consciousness always involves some sense of a unity of
experience i.e. you don’t have to make an effort to fuse all the different kinds of
information streams going on in your head
Commented [IM293]: All of these kinds of information are
o The binding problem – we assemble multiple streams of sensory stimuli into entering your NS and being processed through discrete (may be
event spatially separate) circuits – and coming together as an
ecologically relevant understandable events understood object with a predictable future, at a much later state of
cognitive processing
This is typical of how consciousness feels – if it didn’t your day to day
reality would be choppy and distressing
, o Agency, intention, free will – we have a strong intuition about how we act on
the world, implying a sequence: I see something, I think about it, I make a
decision about what to do next, I output some behaviour
§ This perceived sequence (which is actually somewhat illusory[sic])
creates a sense of agency and free will
o Ownership, ‘embodied cognition’ – our consciousness has a place, it belongs to
us (We feel like we exercise some control over it) and it seems to be co-located
with our bodies – which tends to lead us to the dualistic fallacy Commented [IM294]: ‘im in here – you are all out there’
feeling
o Cartesian duality, the sense of self
These things are about what components combine in to a sense of self – it is related by separate
phenomenon
• Subjectivity
o Most famously described by philosopher Thomas Nagel (70s): What is it like to
be a bat? Commented [IM295]: They are similar in some ways
Some feature sof there day to day life will be fantastically different
§ Qualia – refers to the subjective experience of a sensory stimulus e.g. form ours just because of the ecological niche they inhabit
nociception vs pain
Different from just being conscious, This subjective quality of
§ John Searle (Philosopher) revisited and expanded upon this, as a major consciousness is a separate thing unto itself – that may or may not
problem for neurosciences – ‘the hard problem’ – that may or may not be describable in terms applied to the brain
be addressable by neuroscience Commented [IM296]: What happens at the sensory nerve
ending sthat are detecting either imminent or actual tissue damage
§ To find, in the brain the correlate of consciousness, in this – there are multiple types of specialised receptors (e.g.
burning/temperature, mechanical damage)
subjective sense
§ The Hard Problem – set out many qualifiers for how brain When you touch a stove and jerk your hand away – the action
occurs before your consciousness registers what the pain was
scientists should go about tackling this problem (unconciouss reflex)
§ Inspired disagreements about whether there is a hard problem
It was an unconscious reflex for a reason – axons of thermal pain
at all or if this is an illusory problem that comes down to receptors are Unmyelinated (signal travels slowly) and so it reached
the spinal reflex circuit long before it reached your brain (aware
semantics
thinking cortex)
Whereas the experience of pain itself is a complex feeling involving
not just the painful stimulus and nociception, but also your
emotional reaction – and your perception of what the pain stimulus
Neural Correlates of Consciousness (NCC) is (e.g. miss-identifying extreme cold for burning, because there is an
issue of cognitive cept[sic)
Following Searle’s paper in the 1990s, attempted to give this (consciousness, in the subjective sense)
Pain can vary in how it is perceived subjectively i.e. famously,
a formal definitions and develop framework for its scientific study that would address these people’s pain threshold change under different circumstances
difficulties:
Subjective feeling versus just detecting your own thoughts via
consciousness (nociception)
This framework distinguishes between:
• Background requirements for consciousness
• Global neural correlates of consciousness
• Content-specific neural correlates of consciousness
All of which are addressable by different experimental approaches
Consciousness
Neural Correlates of Consciousness
The problems with identifying a neural correlate/substrate is under defined is because of the word
‘consciousness’ – hard to know what question we are asking
Various meanings of consciousness
Aspects of consciousness
• Wakeful vs inanimate state – whether you are up and walking around and engaging in
behaviour – most critical in a clinical setting
o In everyday life you go through an ordinary sleep between consciousness and
unconsciousness (sleep)
o Dream could be considered its own sense of consciousness
o Anaesthesia – deliberate depression of consciousness, or for the purpose of
vaoiding pain
o A minimally conscious (vegetative)state as a result of a brain injury – used to be
classified on the basis of outward symptoms, but locked-in syndrome (outward
impression of unconsciousness, but aware internally)
§ How much does overt behaviour actually tell us about someone’s state
of consciousness? – Often not nearly as much as we think it should
§ There has been a lot of research to come up with assessing someone’s
subjective state of consciousness (that relies on other measurable
variables)
• Awareness
o Conscious vs unconscious processing
§ Your day is not just considered by careful conscious consideration but
routines, habits, reflexes and cognitive biases (unconscious processing)
o Attention vs inattention (Psychology gorilla experiment) Commented [IM292]: Count how many passes / order the
students made
§ Many stimuli are detected by our nervous system that never reaches our -Paid so much attention to that to do the task, most subjects
conscious awareness – because our attention is focused elsewhere didn’t notice a guy in the gorilla suit walking directly
thorugh the frame
-Most subjects had no recall of the guy in the gorilla suit
Therefore, even when you are globally conscious generally the specific content of your
consciousness is constrained Conclusion: Attention counts quite a bit with regards to the
content of our conciousness
• Unity – any intuitive sense of consciousness always involves some sense of a unity of
experience i.e. you don’t have to make an effort to fuse all the different kinds of
information streams going on in your head
Commented [IM293]: All of these kinds of information are
o The binding problem – we assemble multiple streams of sensory stimuli into entering your NS and being processed through discrete (may be
event spatially separate) circuits – and coming together as an
ecologically relevant understandable events understood object with a predictable future, at a much later state of
cognitive processing
This is typical of how consciousness feels – if it didn’t your day to day
reality would be choppy and distressing
, o Agency, intention, free will – we have a strong intuition about how we act on
the world, implying a sequence: I see something, I think about it, I make a
decision about what to do next, I output some behaviour
§ This perceived sequence (which is actually somewhat illusory[sic])
creates a sense of agency and free will
o Ownership, ‘embodied cognition’ – our consciousness has a place, it belongs to
us (We feel like we exercise some control over it) and it seems to be co-located
with our bodies – which tends to lead us to the dualistic fallacy Commented [IM294]: ‘im in here – you are all out there’
feeling
o Cartesian duality, the sense of self
These things are about what components combine in to a sense of self – it is related by separate
phenomenon
• Subjectivity
o Most famously described by philosopher Thomas Nagel (70s): What is it like to
be a bat? Commented [IM295]: They are similar in some ways
Some feature sof there day to day life will be fantastically different
§ Qualia – refers to the subjective experience of a sensory stimulus e.g. form ours just because of the ecological niche they inhabit
nociception vs pain
Different from just being conscious, This subjective quality of
§ John Searle (Philosopher) revisited and expanded upon this, as a major consciousness is a separate thing unto itself – that may or may not
problem for neurosciences – ‘the hard problem’ – that may or may not be describable in terms applied to the brain
be addressable by neuroscience Commented [IM296]: What happens at the sensory nerve
ending sthat are detecting either imminent or actual tissue damage
§ To find, in the brain the correlate of consciousness, in this – there are multiple types of specialised receptors (e.g.
burning/temperature, mechanical damage)
subjective sense
§ The Hard Problem – set out many qualifiers for how brain When you touch a stove and jerk your hand away – the action
occurs before your consciousness registers what the pain was
scientists should go about tackling this problem (unconciouss reflex)
§ Inspired disagreements about whether there is a hard problem
It was an unconscious reflex for a reason – axons of thermal pain
at all or if this is an illusory problem that comes down to receptors are Unmyelinated (signal travels slowly) and so it reached
the spinal reflex circuit long before it reached your brain (aware
semantics
thinking cortex)
Whereas the experience of pain itself is a complex feeling involving
not just the painful stimulus and nociception, but also your
emotional reaction – and your perception of what the pain stimulus
Neural Correlates of Consciousness (NCC) is (e.g. miss-identifying extreme cold for burning, because there is an
issue of cognitive cept[sic)
Following Searle’s paper in the 1990s, attempted to give this (consciousness, in the subjective sense)
Pain can vary in how it is perceived subjectively i.e. famously,
a formal definitions and develop framework for its scientific study that would address these people’s pain threshold change under different circumstances
difficulties:
Subjective feeling versus just detecting your own thoughts via
consciousness (nociception)
This framework distinguishes between:
• Background requirements for consciousness
• Global neural correlates of consciousness
• Content-specific neural correlates of consciousness
All of which are addressable by different experimental approaches
