1. 8: Attention and Consciousness
Cognitive Neuroscience
David Eagleman
Jonathan Downar

2. 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

3. Chapter Outline
Coma and Vegetative State: Anatomy of the Conscious State
Anesthesia and Sleep: Rhythms of Consciousness
Theories of Consciousness

4. Awareness Requires Attention
Change Blindness
Inattentional Blindness

5. 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.

6. Change Blindness
FIGURE 8.3 Change blindness. Can you see the difference between the two images?
If you don’t see it, look at the tail of the airplane.

7. 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.

8. 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.

9. Inattentional Blindness
FIGURE 8.5 Illustration of the “gorillas in our midst” experiment. Nearly half of all subjects completely failed to notice the gorilla.

10. 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

11. 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.

12. Attentional Orienting Paradigms
FIGURE 8.7 The Posner orienting paradigm. These figures show the sequence of events for this experiment. First, the subject fixates on a “+” sign in the middle of the screen. Then, a cue (an arrow) predicts where the stimulus will appear, followed by a return to the basic fixation condition. Finally, the stimulus appears in one of the two boxes and the subject responds. (a) A valid cue and (b) an invalid cue.

13. 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.

14. 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.

15. 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.

16. Uncoupling Sensory Input from Perception
FIGURE 8.8 Perceptual variance. This image can look like a young woman or an old woman. Hint: The young woman is looking away from you, toward the back of the left side of the picture, and you can see her left ear. The old woman is looking out of the picture, toward the bottom left of the image, and you can see her left eye and her nose and her mouth.

17. 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?

18. 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.

19. Seeking the Correlates of Consciousness
FIGURE 8.9 Brain activity associated with (a) perceived changes or (b) changes that were not perceived.

20. 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.

21. Hemineglect: A Disorder of Attention and Awareness
FIGURE 8.11 Regions of the brain commonly damaged in patients who display hemineglect. Most often, the damage is around the border between the parietal and temporal lobes of the right hemisphere. Less commonly, hemineglect results from damage to the medial motor areas.

22. 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.

23. 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.

24. Neural Correlation of Attention: A Single Network or Many?
FIGURE 8.14 Brain regions activated by exogenous and endogenous shifts of attention. Research suggests that this network of areas is important for both types of attentional shifts.

25. 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

26. 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.

27. The Biased-Competition Model of Attention
FIGURE 8.16 The biased-competition model of attention. (a) When presented alone, a given type of sensory stimulus (such as a face or a house) will activate a specific representation, or pattern of activity, within the lower-level sensory cortex. (b) When a mixture of stimuli are presented, the representations will compete with one another in a "bottom-up" fashion, each attempting to dominate the activity of the lower-level sensory cortex. (c) Top-down influences from higher cortical areas, such as the prefrontal cortex, can bias the competition to enhance one representation and suppress the others. Top-down influences include cognitive factors, such as context.

28. 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.

29. Attention and Single Neurons: Enhancing the Signal
FIGURE 8.17 Microelectrode recording from a monkey performing a visual task.

30. Attention and Single Neurons: Enhancing the Signal
FIGURE 8.18 Effects of attention on neural activity. The neuronal response depends on which stimulus within the receptive field is attended to. This graph represents the level of activity of a cell within V4 to a preferred (face) and nonpreferred (house) stimulus. When both stimuli are presented at the same time and the subject is told to attend to just one of the two objects, the response after about 150 milliseconds resembles the response by the subject to the attended object, regardless of whether the attended object is preferred or nonpreferred.

31. 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.

32. 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.

33. Synchronization, Attention, and Awareness
FIGURE 8.19 Attention affects populations of neurons. (a) In this experiment, researchers recorded the brain activity of a population of neurons in V4 while the monkeys attended to a spatial location to detect a change in the orientation of the presented lines. (b) Results showed that the monkeys’ performance was significantly more accurate for stimuli presented to the attended region as opposed to stimuli presented in the unattended region, but that (c) this difference was not the result of significant changes in the response rate of individual neurons. (d) Rather, there was a significant decrease in the correlated noise within the population of neurons for the attended stimulus as opposed to the unattended stimulus.

34. Synchronization, Attention, and Awareness
FIGURE 8.20 Synchronization of input is important for attention. (a) If several sources of input to a neuron synchronize their activity, it is more likely that they will be able to depolarize the target neuron. (b) If their activity is not synchronized, it is less likely that they will be able to depolarize the target.

35. 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

36. 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.

37. Why Should Synchronization Matter?
FIGURE 8.21 EEG waves associated with different states of consciousness.

38. 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.

39. Why Should Synchronization Matter?
FIGURE 8.22 The effects of synchronization. (a) If the activity of different units in a network can be synchronized, the network can carry patterns of useful information, such as a sequence of letters. (b) If they are not synchronized, no information can be carried.

40. 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.

41. Unconsciousness: Coma and Vegetative State
FIGURE 8.24 Brain activity associated with varying levels of consciousness. The activity in the medial parietal cortex (outlined as a red or blue triangle) is high for conscious subjects, but low for patients in a vegetative state. There is also increasing activity in the medial prefrontal cortex as subjects return to consciousness.

42. 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.

43. 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.

44. Midbrain and Thalamus: Key Players in the Conscious State
FIGURE 8.26 The reticular formation. The reticular formation is a collection of nuclei in the brainstem that project up to the thalamus and cortex and are important for attention and arousal.

45. Anesthesia and Sleep: Rhythms of Consciousness
Sleep: Unraveling the Rhythm of Consciousness
Anesthesia: Reversible, Artificial Unconsciousness

46. 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

47. Sleep: Unraveling the Rhythm of Consciousness
FIGURE 8.27 Characteristic EEG recordings for different phases of sleep.

48. 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.

49. Sleep: Unraveling the Rhythm of Consciousness
FIGURE 8.30 Differences in connectivity between a waking state, light sleep, and deep sleep. (a) Typical connectivity between the medial prefrontal/anterior cingulate cortex (MF), the left and right inferior parietal cortex (IP), and the posterior cingulate (PC) during wakefulness. (b) Connectivity actually increases during light sleep. (c) Connectivity during deep sleep is significantly reduced compared to the waking state.

50. 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.

51. Anesthesia: Reversible, Artificial Unconsciousness
FIGURE 8.31 Brain areas that show decreased activity with anesthesia. The most pronounced reductions are in the thalamus, medial prefrontal cortex, precuneus, and lateral parietal lobe.

52. Theories of Consciousness
Dualism: The Mind-Body Problem
Functionalist Theories of Consciousness
Consciousness and the Integration of Information

53. 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.

54. 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

55. Functionalist Theories of Consciousness
FIGURE 8.32 Brain activation during consciously perceived versus unnoticed changes in visual scenes. If a change in the visual environment activates only the visual cortex, the change does not reach conscious awareness. however, if the activation spreads to a larger network of frontal and parietal areas, then the visual change reaches conscious awareness.

56. 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.

57. Functionalist Theories of Consciousness
FIGURE 8.33 The global workspace theory of consciousness. The brain contains separate systems for sensation, memory, evaluation, attention, and action. The global workspace model coordinates the activity of all these systems.

58. Consciousness and the Integration of Information
The integrated information theory of consciousness suggests:
Consciousness is informative.
Consciousness is highly integrated.

59. Consciousness and the Integration of Information
FIGURE 8.35 Examples of information content and integration. (a) A high-information, low-integration system, such as a large number of people who are each speaking to only one other person. (b) A low-information, high-integration system, such as a large number of people chanting in unison. (c) A moderate-integration, moderate-integration system, such as committees of people reporting to leadership. The possible brain equivalents of these levels of information content and integration are shown below. From left to right: default-mode brain activity in an anesthetized brain, a brain having a seizure, and a working brain.