TASK 7 - CONSCIOUS OR UNCONSCIOUS?

Question 1

amnesia

Answer 1

= amnesic syndrome = deficit in memory

• caused by brain damage or disease
• several types:
  (1) anterograde amnesia, (2) retrograde amnesia, (3) post-traumatic amnesia (4) dissociative amnesia (5) lacunar amnesia (= loss of memory about one specific event) (6) childhood amnesia, (7) transient global amnesia, (8) source amnesia, (9) Korsakoff’s syndrome, (10) drug-induced amnesia, particularly by injection of amnestic drug, (11) situation-specific amnesia, (12) transient epileptic amnesia, (13) semantic amnesia

Question 2

amnesia

- anterograde amnesia

Answer 2

= inability to form new long-term memories

• -> when items leave WM, they are gone
• short-term memory remains intact
• patients can talk, play games, do calculations, remember a phone number long enough to dial it

Question 3

amnesia

- retrograde amnesia

Answer 3

= inability to recall memories before onset of amnesia; loss of long-term memory that stretches back into the past
- episodic memory remains good for the far past (gradient)

Question 4

amnesia

- dissociative amnesia

Answer 4

= resulting from a psychological cause and can include repressed memory, dissociative fugue, and posthypnotic amnesia

Question 5

amnesia

- Korsakoff’s syndrome

Answer 5

= characteristic symptom is confabulation, the production of fabricated, distorted, or misinterpreted memories about oneself or the world

• most common form of amnesic syndrome
• involves both anterograde and retrograde amnesia
• certain types of learning remain unimpaired: (1) classical conditioning (e.g. associating smells with lunchtime) (2) procedural learning (e.g. ability to learn new skills)
• results from long-term alcoholism or malnutrition
• -> caused by brain damage due to a vitamin B1 deficiency
• destruction of (1) mamillary bodies (2) dorsomedial nucleus of the thalamus (3) diffuse damage to frontal lobes

Question 6

amnesia and consciousness

Answer 6

• amnesic syndrome = dissociation between performance and consciousness
• conscious because they are awake, responsive, and able to converse, laugh and show emotion
• -> BUT unable to encode new memories = their self is trapped in the past
• create no memory (or illusion) of a continuous self who lives their life
• TMS can be used to briefly incapacitate small areas of brain tissue
• Wada test: entire hemisphere can be knocked out with barbiturate (= sleep-inducing drug)

Question 7

neglect

- anosognosia

Answer 7

= deficit of self-awareness; person with a disability is unaware of having it

• only occurs with damage to particular parts of right parietal lobe (not with damage to left)
• Damasio: leaving core consciousness intact while damaging extended consciousness that goes beyond here and now
• connections between autobiographical memory and body representation are destroyed

Question 8

anosognosia

- Anton’s syndrome

Answer 8

= patients are blind but insist they can see (confabulate, inventing ingenious range of excuses rather than concluding that they are blind)

• if parts of the visual system are gone there may be no neurones calling for information from the eyes or no neurones able to notice that no information is coming in
• -> perhaps involves no neurones which expect the information = experience no sign that anything is missing
• -> absence of information rather than information about absence e.g. losing the idea of seeing rather than losing the ability for sight

Question 9

neglect

- semi-spatial neglect

Answer 9

= deficit in attention to and awareness of one side of field of vision after damage to one hemisphere (very commonly contralateral to damaged hemisphere)

• do not realise that the left-hand side of the world even exists
• have not lost half of their vision
• deficit of attention: patients simply do not have their attention drawn to the left-hand side of the world

Question 10

neglect and consciousness

Answer 10

• stimuli that are not consciously seen can still affect behaviour
• unattended side is not completely blanked out –> emotional stimuli shown in neglected field can influence attention and stimuli not consciously seen can prime later responses
• house in flames: insisted that houses were identical but said they would prefer to line in the one that was not on flames
• superordinate “subject”: watches the workings of lower mechanism –> subject may not know it, but some part of the brain does
• Bisiach: task of monitoring inner activity is distributed throughout the brain, and when lower-level processors are damaged, higher ones may notice but when higher-level processors are gone there is nothing to notice the lack –> there is no such entity

Question 11

blindsight

Answer 11

= ability of people who are cortically blind to respond to visual stimuli that they do not consciously see; presence of unconscious vision

• due to lesions in their primary visual cortex (V1)
• challenges common belief that perceptions must enter consciousness to affect our behaviour
• converse of Anton’s syndrome
• through neural plasticity and practice, some blindsight patients gradually regain some conscious vision in the blind field, even when V1 is destroyed and the lesion occurs later in life

Question 12

types of blindsight

- type 1

Answer 12

= ability to guess aspects of a visual stimulus (such as location or type of movement) without any conscious awareness of any stimuli (levels significantly above chance)
- spared visual abilities are unaccompanied by any conscious experience

Question 13

types of blindsight

- type 2

Answer 13

= patients claim to have a feeling that there has been a change within their blind area (such as movement) but that it was not a visual percept
- patient reports some form of awareness, but the experience is merely a feeling rather than visual

Question 14

types of blindsight

- action blindsight

Answer 14

= being able to pre-shape and orient hands in flight to match dimensions and orientation of target object when they reach out to grasp it despite not being able to report object’s shape, dimensions, or orientation

Question 15

types of blindsight

- attention blindsight

Answer 15

= covert shifts of attention and aspects of spatial orienting in the absence of visual experience

Question 16

types of blindsight

- affective blindsight

Answer 16

= ability to correctly discriminate emotional stimuli presented within blind field

Question 17

blindsight

- hemianopia

Answer 17

= input from the right visual field goes to the left visual brain, removal of V1 on one side left the patient blind on the other

Question 18

blindsight

- facial expressions

Answer 18

• ability to discriminate between different facial expressions presented in his blind field –> depends on information running through superior colliculus and amygdala
• extensive damage to visual striate cortex on one side, which caused degeneration of cells down through the lateral geniculate nucleus and retina
• other non-cortical visual pathways were left intact

Question 19

blindsight

- detection

Answer 19

• can be detected even though subjects deny consciously seeing anything
  (1) make saccades (eye movement) towards stimuli
  (2) point to the location of objects
  (3) mimic the movement of light or objects in the blind field
  (4) show pupillary and other emotional responses to stimuli
• stimuli in blind field can also prime or bias detection of stimuli in the seeing field

Question 20

blindsight and consciousness

- philosophical zombie

Answer 20

= imaginary being that if did exist would disprove the idea that physical substance is all that is required to explain consciousness (non-materialist stance)

• suggest that consciousness is something separate from the ordinary processes of vision
• blindsight to argue that blindseer has vision without consciousness
• -> people with blindsight would be seen as partial zombies that can see functionally but have none of the visual qualia that go with normal seeing
• reinforces hope of finding a place in brain where consciousness happens (where visual qualia is produced)

Question 21

blindsight and consciousness

- Cartesian theatre/materialist idea

Answer 21

= Cartesian materialist idea of a threshold marking entry into consciousness involves a “magic” difference between those areas that are conscious and those that are not –> Cartesian Theatre where consciousness happens

• same troubles as philosophical zombie
• opponents of this stance have explored several possibilities of difficulties:
  1. blindsight does not exist: people suggest that light may have strayed from the blind field into the seeing field; but stray light cannot account for blindsight
  2. blindsight is nothing more than degraded normal vision: can be tested with prompting confidence ratings for guesses
  3. blindsight might depend on residual islands of cortical tissue: however no activity in V1 can be detected

Question 22

blindsight and consciousness

- functionalism

Answer 22

= whether blindsight disproves functionalism; as functions of vision are met but consciousness is not present

• blindsight experiments: patients are prompted to guess what they see
• -> train blindsight patients (giving them feedback on their guesses), they might realise that they have a useful ability
• -> train patients to make guesses without being prompted, they should be able to spontaneously use information (talk about, act upon) from the blind field, creating a super blind-seer.
• -> if blind seers could use the information about a stimulus in their blind field, does that mean they were conscious of it?
  1. functionalists: blindsight patients would be conscious because being conscious is using stimulus information (function)
  2. epiphenomenalists: blindsight patients would not be conscious because performing the functions and the qualia are separate things

Question 23

blindsight and consciousness

- Block

Answer 23

= blindsight and consciousness confuse (1) access consciousness, (2) phenomenal consciousness

• although blindsight appears to be access consciousness without phenomenal consciousness, it is not
• stimuli in blindsight are both phenomenally and access-unconscious –> because patient denies having any phenomenal experience and because the only access he has, comes from hearing his own voice when he has been forced to make a guess
• -> questions whether phenomenal awareness (what it is like to have an experience) includes whatever cognitive processes underlie access awareness (our ability to report the experience)

Question 24

Riddoch phenomenon

Answer 24

= be aware of certain kinds of stimuli in their blind field

• occurs because the minor visual pathway has projects to V5 (motion sensitive)
• PET activity in area V5: able to detect both slow and fast-moving stimuli but is only aware of fast-moving ones
• -> primary visual cortex is not needed for consciousness but is needed for binding the features of objects –> experience of movement in blindsight includes seeing movement that is not bound to a moving object

Question 25

scotoma

Answer 25

= discrete regions of cortical blindness due to damage to V1 - within these regions, conscious visual awareness is abolished - number of patients show spared visually driven behaviour in their scotoma, despite denial of any conscious visual experience

Question 26

neurological basis of blindsight | - pathways from eye to brain

Answer 26

- blindsight reflects the engagement of multiple pathways from the eye to the brain, many of which do not project towards V1 - -> blindsight occurs when V1 is destroyed but the other areas remain intact - visual middle temporal (MT/V5) area = key cortical area associated with the dorsal stream - there are ten separate parallel pathways from the eye to different parts of the brain

Question 27

blindsight early in life vs. late in life

Answer 27

1. V1 injury early in life: MT neurones continue to show vigorous activity after lesions of V1 in the developing brain - pulvinar afferents to MT outnumber V1 afferents early in life --> pulvinar nuclei more important - strong presence of MT within the developing brain makes it a prime candidate for facilitating visual input in the absence of V1 2. V1 injury later in life: typical MT neuronal responses are more attenuated and their activity for motion and contrast sensitivity resembles response patterns observed in healthy patients’ V1 areas - -> LGN more important

Question 28

pathways from eye to brain | 1. via LGN to V5

Answer 28

- involves the koniocellular layers (K layers) of the LGN - K layers receive visual information from superficial visual layers of the SC - injuries to V1 trigger degeneration of optic radiations and ultimately corresponding retinotopic regions of the LGN - LGN neurones in the K layers can survive V1 lesions - pathway is much smaller than the one projecting from the pulvinar to MT - surviving neurons can maintain connections with the extra-striate cortex (V2, V3, V4). - -> 85% of cells take the route through the lateral geniculate nucleus (LGN) to primary visual cortex (V1)

Question 29

pathways from eye to brain | 2. via pulvinar nuclei to V5

Answer 29

- involves the pulvinar nuclei (thalamus) - pulvinar receives direct retinal input - explains how area MT could receive instructive subcortical input during development (strengthening dorsal stream activity to visual stimuli before V1 input to MT is fully established) - interactions between SC, pulvinar and amygdala have been considered essential for the mediation of affective blindsight - -> support the notion of an unconscious visual pathway that can extract affective features without input from higher-order areas of the ventral visual system (involved in face and object recognition)

Question 30

pathways from eye to brain | 3. superior colliculus

Answer 30

- superior colliculus (SC) can be involved in several cases of blindsight - has connections to both LGN and pulvinar - SC projects directly to premotor neurones in the brainstem --> highly capable of driving residual function, particularly eye movements - -> 15% go via the superior colliculus to various cortical and subcortical areas, which are not affected by the destruction of V1