and Consciousness Cognitive Neuroscience David Eagleman Jonathan Downar Chapter Outline Awareness Requires Attention Approaches to Studying Attention and Awareness Neural Mechanisms of Attention and Awareness ID: 549867
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8: Attention and Consciousness
Cognitive Neuroscience
David Eagleman
Jonathan
DownarSlide2
Chapter Outline
Awareness Requires Attention
Approaches to Studying Attention and Awareness
Neural Mechanisms of Attention and AwarenessSites of Attentional ModulationSynchronization, Attention, and Awareness
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Chapter Outline
Coma and Vegetative State: Anatomy of the Conscious State
Anesthesia and Sleep: Rhythms of Consciousness
Theories of Consciousness
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Awareness Requires Attention
Change Blindness
Inattentional
Blindness
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Change Blindness
It has long been known that there is a connection between attention and awareness.
Stage magicians use covert misdirection to accomplish their craft.
Change blindness is when a person does not notice even a major change in a scene.
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Change Blindness
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Change Blindness
In many real-world examples, people are blind to the changes around them.
People fail to notice when the person they were talking to changes in mid conversation.
People fail to notice differences between two images, such as the tail of the airplane in the previous image.
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Inattentional Blindness
In one experiment, subjects were instructed to count the number of passes one team made in a basketball game.
An actor in a gorilla costume walked through the middle of the game.
Only half the subjects noticed the gorilla.In a more difficult version, only 8% noticed the gorilla.
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Inattentional Blindness
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Approaches to Studying Attention and Awareness
Attentional Orienting Paradigms: Aiming the “Spotlight” of Attention
The Oddball Paradigm: Monitoring a Physiological Measure of Attention
Uncoupling Sensory Input from Perception: Sensory Rivalry
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Attentional Orienting Paradigms
The subject maintains their attention on a fixation cross while the stimulus appears on one of two nearby boxes.
The subject presses a button to indicate where the stimulus is as soon as they notice the stimulus.
A cue may suggest where the stimulus will appear.
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Attentional Orienting Paradigms
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Attentional Orienting Paradigms
If the cue correctly predicts the stimulus, there is a reaction time benefit.
If the cue incorrectly predicts the stimulus, there is a reaction time cost.
Top-down mechanisms focus voluntary (endogenous) attention.Bottom-up mechanisms focus involuntary (exogenous) attention.
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The Oddball Paradigm
The subject is presented with a series of stimuli that are all then same, then a novel stimulus (“oddball”) is presented.
A physiological measure, such as fMRI or EEG, is used to monitor the response to the oddball.
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Uncoupling Sensory Input from Perception
Perceptual rivalry occurs when the stimulus can be interpreted in one that one way.
If you present a different image to each eye, the precept alternates between the two.
Ambiguous figures can also be used.Precepts can often be reversed voluntarily.
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Uncoupling Sensory Input from Perception
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Neural Mechanisms of Attention and Awareness
Seeking the Correlates of Consciousness
Hemineglect: A Disorder of Attention and Awareness
Neural Correlation of Attention: A Single Network or Many?
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Seeking the Correlates of Consciousness
Attention and awareness both involve widespread networks.
If subjects are not attending to a particular stimulus, activation does not spread beyond sensory areas.
If subjects are aware of a stimulus, the activity spreads beyond sensory areas, into frontal and parietal areas.
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Seeking the Correlates of Consciousness
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Hemineglect: A Disorder of Attention and Awareness
Damage to right lateral parietal, lateral premotor, or medial motor areas can cause hemineglect.
In hemineglect, the patient fails to attend to stimuli presented in one side of space, typically the right side.
These deficits are not due to sensory problems.
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Hemineglect: A Disorder of Attention and Awareness
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Hemineglect: A Disorder of Attention and Awareness
The attentional deficit covers multiple sensory modalities
Pointing out the deficits to the patient does not help resolve the problem for more than a brief time.
The unattended stimuli do activate the primary sensory cortices, but the activation does not spread.
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Neural Correlation of Attention: A Single Network or Many?
There are several attentional networks.
Spatial attention involves lateral superior parietal regions.
Nonspatial attention involves lateral inferior temporal regions.
Internally guided spatial tasks involve medial prefrontal and parietal regions.
Attending to the emotions of others involves medial prefrontal cortex and
precuneus
.
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Neural Correlation of Attention: A Single Network or Many?
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Sites of Attentional Modulation: Neurons and Neural Populations
The Biased-Competition Model of Attention
Attention and Single Neurons: Enhancing the Signal
Attention and Local Groups of Neurons
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The Biased-Competition Model of Attention
Different stimuli are represented by activity within large populations of neurons.
Multiple different populations compete to influence behavior and attention selects among these different populations.
Both bottom-up and top-down factors influence which population is selected.
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The Biased-Competition Model of Attention
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Attention and Single Neurons: Enhancing the Signal
In V4, the activity of the neurons is modulated by attention.
The attended stimulus get greater control over the activity of the neuron, increasing the gain of the neuron’s response.
Attention can also decrease the threshold needed to activate a neuron.Attention can increase signal-to-noise ratio.
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Attention and Single Neurons: Enhancing the Signal
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Attention and Single Neurons: Enhancing the Signal
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Attention and Local Groups of Neurons
Researchers record local field potentials to summarize the activity of large groups of neurons.
Attention seems to reduce the correlated noise in a population of neurons, making the signal more apparent and obvious.
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Synchronization, Attention, and Awareness
Synchronization links the activity of different neurons in different parts of the brain.
This may provide a solution to the binding problem.
Attention can increase synchronization in pairs and in populations of neurons.
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Synchronization, Attention, and Awareness
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Synchronization, Attention, and Awareness
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Coma and Vegetative State: Anatomy of the Conscious State
Why Should Synchronization Matter?
Unconsciousness: Coma and Vegetative State
Midbrain and Thalamus: Key Players in the Conscious State
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Why Should Synchronization Matter?
Sleep, coma, and vegetative state are altered states of consciousness.
Synchronization at high frequencies (about 40 Hz) leads to attention.
Synchronization at lower frequencies (about 10 Hz) does not produce attention.
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Why Should Synchronization Matter?
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Why Should Synchronization Matter?
One proposal is that synchronization is just the means to communicate more efficiently.
By synchronizing the activity of different neurons, useful patterns of information emerge.
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Why Should Synchronization Matter?
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Unconsciousness: Coma and Vegetative State
Brain activity differs in different levels of consciousness.
Activity in low level sensory areas is similar in comatose and recovered patients.
In recovered patients, activity increases in the lateral and medial prefrontal and parietal cortex.
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Unconsciousness: Coma and Vegetative State
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Midbrain and Thalamus: Key Players in the Conscious State
Neurons in the midbrain reticular activating system project throughout the cortex.
When the organism is alert, these neurons fire at a high rate.
The firing rate slows down when the organism is asleep.Activity within the reticular activating system helps maintain consciousness.
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Midbrain and Thalamus: Key Players in the Conscious State
The
intralaminar
nuclei of the thalamus interact with the reticular activating system to maintain awareness.These nuclei are particularly vulnerable to oxygen deprivation.Deep brain stimulation of the
intralaminar
nuclei is a potential treatment to restore consciousness.
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Midbrain and Thalamus: Key Players in the Conscious State
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Anesthesia and Sleep: Rhythms of Consciousness
Sleep: Unraveling the Rhythm of Consciousness
Anesthesia: Reversible, Artificial Unconsciousness
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Sleep: Unraveling the Rhythm of Consciousness
Sleep is divided into multiple stages.
Non-Rapid Eye Movement (NREM)
Three stagesNot associated with dreamingOverall reduction in metabolic activity
Rapid Eye Movement (REM)
This stage is where dreams typically occur
Metabolic activity similar to awake state
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Sleep: Unraveling the Rhythm of Consciousness
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Sleep: Unraveling the Rhythm of Consciousness
During sleep, the activity of different areas is desynchronized.
When awake, TMS stimulation activates a wide network of areas.
When asleep, TMS stimulation fades out without spreading widely.
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Sleep: Unraveling the Rhythm of Consciousness
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Anesthesia: Reversible, Artificial Unconsciousness
Anesthetics inhibit neuronal activity.
As anesthetic dose is increased, metabolic activity in the brain decreases.
At some point, consciousness is abruptly lost.Activity in high order association areas is reduced.
Significant decrease in thalamic activity.
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Anesthesia: Reversible, Artificial Unconsciousness
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Theories of Consciousness
Dualism: The Mind-Body Problem
Functionalist Theories of Consciousness
Consciousness and the Integration of Information
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Dualism: The Mind-Body Problem
Dualism is the idea proposed by Descartes that the mind and the brain are two different things.
Today, few accept this as correct.
Nonmaterial faculties such as memory or emotion are now understood to be outgrowths of the brain.
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Functionalist Theories of Consciousness
Mental states depend on the functional role they play.
The higher-order theory of consciousness suggests that a conscious perception requires:
A lower-order representationA higher-order representationA functional link that connects the two
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Functionalist Theories of Consciousness
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Functionalist Theories of Consciousness
The global-workspace theory of consciousness suggests
There are many separate subunits within the brain.
Consciousness involves coordinating activity with these subunits.
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Functionalist Theories of Consciousness
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Consciousness and the Integration of Information
The integrated information theory of consciousness suggests:
Consciousness is informative.
Consciousness is highly integrated.
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Consciousness and the Integration of Information
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