Download Eagleman Ch 8. Attention and Consciousness

8: Attention 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
 Sites of Attentional Modulation
 Synchronization, 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 stages
 Not associated with dreaming
 Overall 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 representation
 A higher-order representation
 A 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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