Attention & Consciousness

Question 1

Describe endogenous and exogenous attention and be able to give an example of each

Answer 1

endogenous: voluntary, goal-directed, prior knowledge, top-down
exogenous: reflexive, automatic, naturally salient, bottom-up
ex: Posner Orienting Paradigm

—> subject looks at screen with 2 boxes and cross in center
—> told to maintain fixation on center cross
—> target stimulus will appear at random in one of the two squares —> subject must press button as quickly as possible
—> voluntary/endogenous cues = arrow
—> involuntary/exogenous cues = blinking

(arrow is endogenous because the subject still must choose to focus on the box it points to/or can ignore)

(blinking is exogenous because it causes the subject to be drawn to the salience of the cue not on his/her own accord)

—> ORIENTING PARADIGM ALLOWS US TO STUDY TWO MECHANISMS OF ATTENTION:

TOP-DOWN ENDOGENOUS MECHANISMS (BY WHICH WE DELIBERATELY FOCUS ON A SUBJECT—coming from within)

BOTTOM-UP EXOGENOUS MECHANISMS (BY WHICH OUR ATTENTION JUMPS TO SALIENT FEATURES OF ENVIRONMENT—coming from outside)

traffic light=top-down
pedestrian running in street

Question 2

Define arousal, awareness, and attention

Answer 2

arousal: arousal: a global state of alertness; awake and stimulated to action or readiness to act

attention: knowledge or perception of a situation
or fact

awareness: selective allocation of resources to
certain stimuli, usually at the expense of others

Question 3

Describe the cocktail party effect and what this illustrates about attention

Answer 3

being able to focus one’s auditory attention on a particular stimulus while filtering out a range of other stimuli

much the same way that a partygoer can focus on a single conversation in a noisy room

“tune into” a single voice and “tune out” all others

Question 4

Describe how dichotic listening tasks work and some experimental findings associated with these tasks, e.g., what aspects of the sounds coming in to the unattended ear can people perceive vs. not perceive

Answer 4

studying selective attention

observer pay attention to one of two different messages, each delivered to one ear over stereo earphones

ignore one side’s prose, listen and repeat the other side

observers repeat the shadowed message in a stiff voice, showing that they are putting out quite a bit of effort to do the shadowing well

did not notice if ignored voice changed sex or language…SUGGESTING THAT THE SELECTIVITY OF CONSCIOUSNESS CAN WORK TO TUNE INTO SOME INFORMATION

Question 5

Describe inattentional blindness and give an example of it

Answer 5

phenomenon where subjects fail to notice a stimulus when their attention is focused elsewhere
ex: gorilla in our midst

Question 6

Describe change blindness, give an example of it, and describe fMRI findings regarding activity in our brains

Answer 6

————————-
WHAT IS IT
inability to tell the difference between two similar visual scenes when presented sequentially, with a brief interruption or distraction at the time of change

if we distract attention with a flicker in the scene, a page turn, or an eye movement, major changes in the scene may completely escape our awareness
mudsplashes: things that draw our attention elsewhere

————————-
EXAMPLES
ex: ask for direction —> interrupted by movers —> asker is replaced —> only about half of subjects noticed a change

ex: series of photos with brief interruption

————————-
MRI TESTS
—> MRI: present subjects with subtle change in an image and compare brain activation when patient detects and does not detect change

—> VISUAL CORTICES ACTIVE when changes occurred, but widespread activation (lateral prefrontal and parietal) only took place when subjects were aware of change

————————-
IMPLICATIONS
—> we are actually aware of much less of the world than we might think

Question 7

What is change blindness

Answer 7

inability to tell the difference between two similar visual scenes when presented sequentially, with a brief interruption or distraction at the time of change

Question 8

Describe how masking works and the differences in brain activity we see when people consciously vs. unconsciously perceive a stimulus

Answer 8

manipulating conscious perception by flashing a target stimulus and then replacing or “masking” it with another, so that the first is not consciously received

ex: subjects viewed words flashed on screen before being masked by another stimulus—if flash duration was brief, subjects recorded they were not aware of a word appearing—however, if asked to guess the word from a list, they tended to guess correctly, far more than chance

—>still had unconscious perception of the word, although conscious perception absent

in fMRI, the masked words activated visual cortices even when not consciously reported—when aware of flashed word, widespread activation occurred (lateral prefrontal and parietal)

Question 9

What is masking

Answer 9

manipulating conscious perception by flashing a target stimulus and then replacing or “masking” it with another, so that the first is not consciously received

Question 10

What does perception versus activation in different brain areas implicate?

Answer 10

visual cortices activation in unaware patients, widespread activation in aware patients

—>activation of visual cortex alone is not sufficient for conscious perception

—>what is needed is activation in a widespread network of brain regions in the FRONTAL, PARIETAL, AND TEMPORAL cortices

Question 11

Describe how binocular rivalry works, what we typically see, and changes in brain activity that occur when we “flip” from seeing the stimulus coming into one eye vs. the other

Answer 11

when two different images are presented to the two eyes—you don’t see both simultaneously nor do you see a fusion—instead, you perceive one image alternating sporadically with the other

visual system locked in a battle with two conflicting interpretations

fMRI implications: network of lateral prefrontal, medial prefrontal, parietal and temporal areas show increased activity during changes in perceived image, suggesting activity in these areas important for conscious perception

ex: stereoscope — creates 3D scene by presenting slightly different 2D perspectives of the same image
ex: old and young woman

Question 12

Describe hemispatial neglect and some behavioral results associated with it. Identify where the damage in the brain typically occurs and describe what happens behaviorally and in terms of brain activity when people with hemispatial neglect are presented with
objects in their unattended (usually left) visual field

Answer 12

a disregard of one half of the world, typically on left side

caused by damage to the right parietal lobe
nothing wrong with visual system, issue is being able to place attention on left side of world

——> fMRI STUDIES: while person with hemineglect is presented with an object in their left visual field — they report not seeing the object — but primary and secondary visual cortices seem to have processed it

being aware of deficit doesn’t seem to alter them

Question 13

Describe Balint’s syndrome

Answer 13

Balint’s Syndrome:
damage to parietal lobes (dorsal stream) on both sides

—patients have a functioning ventral stream (therefore can recognize objects) but damage to the dorsal stream (parietal lobes) causes them to loose attention to the big picture of a scene

—when looking at complex visual scenes, patients will see details, not understanding the big picture

—major symptom: SIMULTAGNOSIA inability to recognize multiple elements in a scene ~~ aka when looking at scene, they will see details, not understanding the bigger picture

Question 14

Describe the results of the fMRI experiment in which participants were shown pictures of faces and scenes and in different blocks told to passively view them, attend to faces and ignore scenes, and attend to scenes and ignore faces

Answer 14

biased competition model:

— at the neural level, different ensembles compete to control behavior—the winner depends on intrinsic, bottom-up factors such as pitch, volume, etc. and top-down biases such as current behavioral context

— when presented alone, a given stimulus (such as a face or house) will activate a specific representation or pattern of activity in the lower-level sensory cortex

—when a mixture of stimuli are presented, the representations compete in a bottom-up fashion to dominate the lower-level sensory cortex

—top-down influences from higher cortical areas, such as the prefrontal cortex, can bias the competition to enhance on representation over another—top-approaches can be cognitive factors, such as context

Question 15

Describe synchronization and what happens when there is too much synchronization in
the brain

Answer 15

synchronization: simultaneous firing of neurons in different areas, allows the brain to communicate more efficiently

if several sources of input to a neuron synchronize their activity, it is more likely the they will be able to depolarize the target neuron — if activity is not synchronized, it is less likely that they will be able to depolarize target

can link together the activity of distant neurons — possible solution to the binding problem

too much synchronization =

synchronized activity throughout the entire cortex —> epileptic seizure —> when all of the neurons of the cortex are firing together, the patient completely looses consciousness, and afterwards, are severely disoriented and have no recollection of their experiences during the seizure

Question 16

Identify what PET scans look like of people who are conscious and in a resting state, brain death, vegetative state, minimally conscious state, and locked-in syndrome

Answer 16

increased activity in MEDIAL PARIETAL and PREFRONTAL cortex = greater consciousness

EEG shows flatline for brain dead patients

Question 17

What area of the brain implicates high consciousness

Answer 17

medial parietal cortex

prefrontal cortex, precuneus, and thalamus

Question 18

Roughly locate and describe the role of the midbrain’s reticular formation

Answer 18

reticular formation of brainstem:
collection of nuclei in the brainstem that project up to the thalamus and cortex and are important for attention and arousal

neurons in the reticular formation fire up arousal levels — rather than sending outputs down the spinal cord, they send them up to the thalamus and cortex
constant, high firing = wakefulness, low frequency firing

Question 19

Describe the function of the intralaminar nuclei in thalamus and how it relates to consciousness

Answer 19

intralaminar nuclei: part of thalamus; relay input from brainstem pertaining to alert and arousal, such as the reticular formation

damage to intralaminar nuclei (asphyxiation/loss of oxygen) —> coma

Question 20

Describe how brain activity changes during sleep

Answer 20

— reduction in brain activity during sleep in lateral prefrontal and parietal cortex, medial prefrontal, and precuneus; also reduced activity in pons, caudate nucleus, hypothalamus, thalamus

— in other words, many areas with reduced activity during sleep are areas we discussed as important for awareness and attention

— brainstem reticular neurons switch from continuous/tonic firing to bursting/phasic firing (in thalamus too)

while awake, the distant areas of the brain communicate through long-range cocortical connections —> connections disrupted during deep sleep (coordinated discussion to a million separate conversations) and strengthened during light sleep

Question 21

Roughly identify a few key regions of the default mode network and explain what we’re doing/thinking when we’re in this default mode

Answer 21

• “default state” of mind wandering: thinking about the
  FUTURE, PAST, HYPOTHETICALS, or HERE-AND-NOW
• medial prefrontal, parietal, hippocampus (damage)
• patients with hippocampal lesions had amnesia, but also could not imagine new hypothetical events
  functionally connected areas that seem to be most active when we’re awake but not engaged in a specific task
• tend to be active when we’re thinking about future or past, imagining hypothetical events, and other activities associated with “mind wandering”
• hippocampal cortex, paracampal cortex…medial prefrontal cortex, inferior parietal lobe, posterior cingulate and precuneus, medial temporal lobe

Question 22

Describe changes in brain activity that occur during anesthesia and explain how it makes sense that these regions – prefrontal cortex, thalamus, precuneus – show less activity

Answer 22

• under anesthesia see dramatically reduced activity in these same key regions:

PREFRONTAL CORTEX, PRECUNEUS, THALAMUS

• the cortical areas affected by anesthesia match up with the cortical areas involved in the conscious state and its contents, as seen in studies of coma and neglect
• we see pronounced decrease in thalamic activity as we shift into unconsciousness

Question 23

Precuneus

Answer 23

medial part of the parietal lobe, along midline of brain

important for memory formation and retrieval and orientation to time and place

Question 24

“My experience is what I attend to”

Answer 24

although it appears that we are conscious of everything around us, in fact, we are only perceiving a tiny fraction of the world —> this tiny fraction is the focus of our attention

Question 25

Discuss ideas suggested in the Radiolab episode about how consciousness is achieved and Frick and Koch’s hypothesized role of the claustrum

Answer 25

Is the claustrum the seat of consciousness, as Koch & Frick posit?

Christof Koch asks: who conducts the brain chorus?

no “little conductor” — places in the brain that act akin to a conductor that synchronize and coordinate the various parts of the brain that work independently

everything’s integrated — you need some sort of entity that pulls all of this together

claustrum = “hidden away” this structure receives input from almost every cortical area, seems to be in an ideal position for synchronization

PROOF? too soon to know, but…

• consciousness on-off switch in the brain — woman with epilepsy, electrodes in the brain — when electrodes near a region called the claustrum were stimulated in the woman’s brain, she lost consciousness
• Koch uncovered three giant neurons stemming from the claustrum and connecting to many regions in both hemispheres of the brain — one of those neurons wraps around the entire brain like a “crown of thorns”
• Koch believes that the giant neuron may be coordinating signals from different brain regions to create consciousness

Question 26

Explain how synchronization might be related to consciousness, but why we cannot simply say that the lack of synchronization causes unconsciousness

Answer 26

when we say that conscious perception involves widespread synchronization, it is tempting to jump to neural synchronization=attention=consiousness

synchronization is simply a mechanism that allows the brain to communicate information more efficiently among neurons

it is not synchronization itself that accounts for consciousness, but the information states it allows to be relayed

(a) normal connections in wakefulness
(b) strengthened connections in light sleep
(c) decreased connections in deep sleep

Question 27

Describe broadly what would happen if you TMS’d an area of the brain like the prefrontal cortex during wakefulness vs. during anesthesia

Answer 27

send electrical signal through brain—> see how it echoes

more spread=stronger cortical connections

anesthesia: pronounced reduction

Question 28

Explain how researchers cleverly used fMRI to discover that a patient who seemed to be in a vegetative state was actually minimally conscious

Answer 28

unlike with vegetative state, patients with MCS have partial preservation of conscious awareness

• A MCS also has a poor prognosis, but it is better than a PV state
• may also experience pain and therefore require pain medication

Question 29

locked-in syndrome

Answer 29

Locked-in syndrome (LIS) is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for vertical eye movements and blinking