Lecture 10 -Neurobiology of Consciousness

Question 1

What is one dimension of consciousness?

Answer 1

The ability to recognize oneself as a distinct entity

Question 2

How is self-recognition tested in animals?

Answer 2

Using the mirror recognition test. Animals who recognise themselves will touch their own bodies instead of the mirror.

Question 3

How do animals initially react to mirrors and what changes occur over time during the test?

Answer 3

Animals first react to mirrors as if facing another animal but, within 5-30 minutes, they start self-exploration, showing self-awareness.

Question 4

What does the behavior of prosopagnosia patients reveal about self-awareness?

Answer 4

Prosopagnosia patients show that self-awareness goes beyond visual self-recognition, as they can’t identify themselves in a mirror despite having a sense of self.

Question 5

What evidence suggests that certain bird species, like ravens and crows, possess consciousness?

Answer 5

• Ravens, crows, and jays exhibit abstraction, cause-and-effect understanding, tool use, and problem-solving.
• Unique tool use in isolated populations suggests cultural transmission, advanced cognition, and conscious adaptation.

Question 6

What does the delay in awareness of intention suggest about consciousness?

Answer 6

The delay suggests that there are different levels of consciousness, where the brain initiates motor movement before we become consciously aware of our own intentions.

Question 7

What key question about human behavior does the lag in awareness of intention raise?

Answer 7

It raises the question of “free will,” as the brain appears to “decide” actions before conscious awareness of the intention occurs.

Question 8

What experimental task did participants perform to study levels of consciousness?

Answer 8

Participants watched letters flash on a screen and could decide randomly when to press a button, while fMRI recorded brain activity before and after decisions were made.

Question 9

What brain activity occurs before a conscious decision is made?

Answer 9

Decision-making regions in the frontal cortex activate 5-10 seconds before the decision becomes conscious, followed by motor cortex activation just before the action.

Question 10

What condition did patient “GK” experience following a right parietal stroke?

Answer 10

Patient “GK” experienced “visual extinction,” claiming inability to consciously detect visual stimuli.

Question 11

What did BOLD imaging of V1 reveal in patients with right parietal cortex damage?

Answer 11

V1 processes visual input without awareness, but the parietal cortex is needed to make us consciously aware of it.

Question 12

How does brain activity change in the frontoparietal network during unconscious states?

Answer 12

1. During sleep: Downregulation begins in the dorsolateral prefrontal cortex and posterior parietal cortex.
2. During anesthesia: Deactivation areas expand to include regions like the medial frontal cortex.
3. In persistent vegetative state: Dramatic reduction in activity occurs across these regions, especially the parietal cortex and precuneus, show almost no activity, indicating these are essential for consciousness.

Question 13

What brain network and regions is primarily implicated in different levels of consciousness? How do they behave across different states of unconsciousness?

Answer 13

The frontoparietal network, including the dorsolateral prefrontal cortex and posterior parietal cortex, precuneus (Pr), and mid-frontal areas (MF) play a key role in maintaining consciousness

Question 14

What is the “binding problem” in consciousness?

Answer 14

It is the challenge of how the brain coordinates activity across different regions to combine sensory information into a unified perception.

Question 15

What is the role of gamma frequency (40Hz) in the brain?

Answer 15

Gamma frequency enables transient synchronization of neuron activity, facilitating the integration and binding of information across brain networks. (simply:Gamma frequency helps neurons briefly sync up, allowing different brain areas to “talk” to each other at the same time. This helps the brain connect and combine information from different sources and over time, like linking the sight of a dog with the sound of its bark)

Question 16

How do neurons create a unified representation of a sensory event?

Answer 16

Neurons representing the same event fire together to create a single, unified understanding of that event (e.g., seeing a dog and hearing it bark at the same time).

Question 17

How was fMRI used to assess consciousness in coma patients, and what mental tasks were involved?

Answer 17

fMRI was used to detect brain activity by asking patients to imagine playing tennis (activating the supplementary motor area, SMA) for “yes” and walking through a house (activating the parahippocampal place area, PPA) for “no.”

Question 18

What did the results of the fMRI study reveal about brain activity in coma patients compared to healthy controls?

Answer 18

The results showed a high overlap between brain activation patterns in control subjects and coma patients, suggesting that some coma patients retain a level of consciousness.

Question 19

What happens to the fusiform face area (FFA) and superior temporal sulcus (STS) responses when face perception is suppressed?

Answer 19

FFA response diminishes when face perception is suppressed, but the STS response remains active, particularly for fearful faces.

Question 20

What do the results of suppressed face perception studies suggest about emotional processing?

Answer 20

Emotional stimuli, such as fearful faces, can elicit responses in brain regions like the STS even without conscious awareness.

Question 21

What is the concept of binocular rivalry and how does it relate to changes in awareness?

Answer 21

• Occurs when each eye is presented with a different image, and the brain alternates between perceiving one image or the other.
• This shift in awareness demonstrates how our conscious perception can change when the brain faces competing stimuli.

Question 22

What brain areas are implicated in passive monitoring of conscious perception?

Answer 22

Posterior cortical areas are involved in passive monitoring of conscious perception.

Question 23

Which physiological measures correlate with perceptual dominance in binocular rivalry?

Answer 23

Pupil dilation and eye movements change when the brain focuses on one image, reflecting perceptual dominance.

Question 24

How does binocular rivalry help study shifts in consciousness, such as waking from sleep?

Answer 24

It allows researchers to observe how the brain handles spontaneous fluctuations in awareness.

Question 25

What does the state-specific task during REM and NREM sleep involve and what brain activity is associated with conscious dream experiences during REM and NREM sleep?

Answer 25

-Participants are awakened during REM/NREM sleep and asked about their dreams.

• High-frequency activity in the posterior parietal cortex is linked to conscious dreaming, especially for categories (e.g faces, spatial settings, movements)

Question 26

How does the “no reporting of seen vs. not seen” experiment work and what is its finding?

Answer 26

-Participants don’t report if they see the face; pupil dilation and eye movements are used to measure awareness.
- Temporo-occipital network is active during perception, regardless of reporting

Question 27

What does the “report of awareness” paradigm involve and what brain regions are involved in conscious face recognition

Answer 27

• Participants view faces with different levels of image noise and report if they see the face.
• Found that temporo-occipital- parietal areas are involved in conscious face recognition.

Question 28

Which brain area mediates binocular rivalry and what is its function?

Answer 28

• Binocular rivalry is mediated by neurons in the inferotemporal cortex.
• The inferotemporal cortex is involved in high-level visual processing.

Question 29

What was the setup of the monkey experiment to study inferotemporal cortex activity?

Answer 29

• The monkey was trained to pull left or right levers to indicate whether an object belonged to the left or right group.
• Neural recordings were taken from inferotemporal cortex neurons while the monkey performed the task

Question 30

How did binocular rivalry affect the monkey’s conscious awareness in the experiment?

Answer 30

• A starburst was presented to the left eye and a monkey face to the right eye, creating a rivalrous condition.
• This condition caused an alternation in conscious awareness between the two images.

Question 31

What was the relationship between IT neuron activity and the monkey’s perception during binocular rivalry?

Answer 31

• The IT neuron was excited by the monkey face but not the starburst.
  -The firing pattern of IT neurons matches the monkey’s perception of a face, showing its conscious awareness of it.

Question 32

What role does thalamic activity play in consciousness, and what happens with lesions in the intralaminar nuclei?

Answer 32

• Postulated that thalamic
  activity may be necessary for consciousness
• Lesions in the intralaminar nuclei of the thalamus can lead to coma

Question 33

How did thalamic stimulation affect comatose patients, and what was the duration of its effects?

Answer 33

• Thalamic stimulation improved arousal, limb control, and oral feedings in comatose patients.
• These effects were transient

Question 34

Where does the claustrum receive input from, and what role does it play in consciousness?

Answer 34

-Receives input from virtually all cortical regions and sends projections back, acting as an integrator.
- It provides the “gist” of sensory information to the cortex on a fast timescale. (e.g when ur in a room it combines what you see and hear, then quickly sends this information back to the brain, helping you stay aware of your surroundings)

Question 35

What did the experiment with an epileptic patient show about the claustrum’s role in coordinating consciousness? What happened when stimulation was turned off?

Answer 35

• Electrical stimulation of the claustrum caused the patient to lose consciousness.
• Consciousness resumed when the stimulation was turned off, suggesting the claustrum coordinates the stream of consciousness.

Question 36

How does visual imagery relate to visual consciousness?

Answer 36

• ## Visual imagery activates similar brain processes as external visual stimuli in the entorhinal cortex.

Question 37

What did the experiment on visual imagery and entorhinal cortex neurons reveal?

Answer 37

Entorhinal neurons selectively responded to a dolphin
-Imagining a dolphin elicited similar neural responses to actually seeing it.

Question 38

What causes Conduction Aphasia and which brain regions are involved?

Answer 38

Conduction Aphasia is caused by lesions in the arcuate fasciculus, disrupting communication between the frontal and parietal lobes.

Question 39

How does Conduction Aphasia affect language abilities? (3)

Answer 39

• Impairs word repetition
• Impairs ability to respond appropriately to heard communication
• Comprehension and spontaenous speech remain in tact

Question 40

What causes Wernicke’s Aphasia and how does it affect lanauge? (aka. sensory or receptive aphasia)

Answer 40

• Damage to Wernicke’s area, located in the posterior temporal lobe.
• Impaired comprehensinon despite producing fluent but nonsensical speech.

Question 41

What evidence suggests that animals have sophisticated communication abilities? (2)

Answer 41

1. Bees, birds, monkeys, and whales exhibit sophisticated communication.
2. Great apes like chimps can use sign language or manipulate symbols on keyboards.

Question 42

How do chimps’ communication abilities compare to humans?

Answer 42

Chimps communicate using gestures, facial expressions, and objects, with vocabularies comparable in complexity to those of young children.

Question 43

Which brain regions are activated in monkeys when processing conspecific calls, and how do they compare to human brain areas?

Answer 43

1. Frontal and temporal lobes are activated in response to conspecific calls.
2. These regions are homologous to Broca’s and Wernicke’s areas in humans.

Question 44

What does the activation of frontal and temporal lobes in monkeys suggest?

Answer 44

It suggests these areas play a role in communication, similar to their function in human speech production and comprehension.

Question 45

What is Aphasia and what does it result from?

Answer 45

• Disorder impairing language production or comprehension
• Caused by damage to the left hemisphere (e.g., Broca’s area)

Question 46

How did Paul Broca contribute to understanding language localization? (3)

Answer 46

1. Localized language production to ventroposterior frontal lobe (Broca’s area)
2. Showed left hemisphere damage leads to loss of meaningful language production
3. Evidence from patient “Tan,” who could only say “tan” despite understanding language