Learning

Question 1

What is perceptual learning?

Answer 1

An increase in the ability to extract information from the environment as a result of experience and practice with stimulation coming from it

Defined by Eleanor Gibson in 1969.

Question 2

What does the phrase ‘Practice-makes perfect’ imply in the context of perceptual learning?

Answer 2

With practice, individuals can achieve high levels of perceptual expertise in detecting and distinguishing sensory stimulation

Attributed to William James, 1890.

Question 3

What are the key principles governing perceptual learning?

Answer 3

• Specificity
• Generalisation
• Consolidation

These principles help understand how perceptual learning occurs and its effects.

Question 4

What role do regulatory factors like sleep and attention play in perceptual learning?

Answer 4

They are crucial for enhancing and consolidating perceptual learning

Sleep is particularly important for consolidation.

Question 5

List examples of perceptual learning in the natural world.

Answer 5

• Identifying injury and disease in x-rays and brain scans
• Bird watching (visual and auditory learning)
• Categorical discriminations (e.g., faces of different races, color categories)

These examples illustrate how perceptual learning is prevalent in everyday life.

Question 6

What determines the amount of learning in perceptual tasks?

Answer 6

Initial performance levels

The poorer the initial performance, the more learning that occurs.

Question 7

True or False: Perceptual learning requires error-correcting feedback.

Answer 7

False

Improvement can occur even without external error feedback.

Question 8

What is the significance of sleep in perceptual learning?

Answer 8

Sleep is critical for consolidation of perceptual learning

Deprivation of sleep can nullify learning on perceptual tasks.

Question 9

Fill in the blank: Perceptual learning is often specific to the _______ and _______ used during training.

Answer 9

[trained task] and [stimuli]

Question 10

What are the three potential outcomes of transfer experiments in perceptual learning?

Answer 10

• No transfer of learning
• Partial transfer of learning
• Full transfer of learning

These outcomes help assess the generalization of learned skills.

Question 11

What did Fiorentini & Berardi (1980) demonstrate about perceptual learning?

Answer 11

Practice improved grating phase discrimination, but learning did not transfer to gratings rotated by 90 degrees

This shows the specificity of perceptual learning.

Question 12

What is the relationship between task difficulty and learning transfer?

Answer 12

The amount of transfer is determined by the difficulty of the task

Easier tasks tend to show more transfer of learning.

Question 13

What did Ahissar and Hochstein (1997) find regarding visual search tasks?

Answer 13

Full transfer of learning occurred between ‘easy’ initial training and subsequent ‘easy’ transfer tests

No transfer occurred between two difficult tasks.

Question 14

What are the two models for consolidation during sleep?

Answer 14

• Synaptic Homeostasis Model
• Reactivation Model

Each model explains different mechanisms by which sleep aids in consolidating learning.

Question 15

What is ‘task-irrelevant perceptual learning’?

Answer 15

Subjects learn to discriminate between stimuli to which they are exposed but upon which they perform no task

Proposed by Watanabe et al. (2001).

Question 16

Describe the role of top-down attention in perceptual learning.

Answer 16

It activates cognitive strategies, voluntarily biasing attention towards important visual features

Essential for producing perceptual learning according to Ahissar and Hochstein.

Question 17

Describe the role of bottom-up attention in perceptual learning.

Answer 17

Involuntary shifts of attention induced by the presentation of a salient feature

Suggests that perceptual learning can occur without top-down attention.

Question 18

What was found in the study by Frenkel et al. (2006) regarding bottom-up attention?

Answer 18

Repeated presentations of grating stimuli resulted in a persistent enhancement of visual evoked potentials in mouse visual cortex

This suggests that bottom-up attention may contribute to perceptual learning.

Question 19

What is the effect of sleep deprivation on perceptual learning?

Answer 19

It nullifies learning on perceptual tasks

Highlighted by studies from Karni et al. and Gais et al.

Question 20

What is the relationship between the complexity of tasks and the extent of perceptual learning?

Answer 20

More perceptual learning occurs on complex tasks

Tasks requiring multiple perceptual dimensions show greater learning.

Question 21

How long can learned improvements in perceptual tasks be retained?

Answer 21

For 2-3 years

This indicates the relatively permanent nature of perceptual learning.

Question 22

practice on very simple perceptual tasks improve with practice, such as

Answer 22

• vernier discrimination
• orientation discrimination
• stereoscopic depth discrimination

in 1970s-80s, improvements in this were attributed to cognitive changes

• Vernier: display where ask ppts to fixate on centre of screen. Present 2 bars, top and bottom, displaced from each other. Is top bar on left or right of bottom. Find JND
• Orientation: 2 orientated patterns. Is the one on the right tilted to left or right compared to target. Find minimum orientation to detect a difference (concept of JND)
• Stereoscopic: centre positioned to front or back
• all hyperacuity tasks
• cortical level of brain rather than retina

Question 23

there is more perceptual learning on complex tasks

Answer 23

• fine & jacobs (2002) compared amount of learning in 16 human studies
• tasks using stimuli with external noise showed more learning than low level tasks
• complex tasks that required discriminations along more perceptual dimensions showed more learning

the more complex a task is, the more learning that is involved

Question 24

amount of learning inversely related to initial performance levels

Answer 24

• fahle & henke-fahle (1996) measured the relationship between subjects initial level of performance on a vernier discrimination task and the amount they learnt of the task
• the poorer the performance was before training the more they learnt on the task

starting threshold impacts how much you improve

Question 25

amount of learning inversely related to initial performance levels

Answer 25

* astle et al. (2012) tested whether the same factors that limit performance on a task limit learning on the same task * prior to learning, vernier discrimination performance was either unmatched or equated in 2 different ways * the magnitude of learning was a constant proportion of initial performance levels

Question 26

perceptual learning is specific to the trained task and stimuli

Answer 26

* subjects repeatedly practice and improve their visual performance on a task over several training sessions * after a period of time, the task or stimulus is changed to test for transfer of learning * there are three potential outcomes: no transfer of learning, partial transfer, full transfer

Question 27

perceptual benefits of learning are retained over many years

Answer 27

* with sufficient training, there is very little forgetting of the learned improvements on a visual discrimination task * learned improvement on a figure-ground texture discrimination task were retained for 2-3yrs ## Footnote * % correct and stimulus onset asynchrony: through training, to reach 80% the SOA decreases in terms of milliseconds * test again after 32 months: retaining of learning throughout time, not exactly the same but still close * retained performance

Question 28

sleep has a critical role in the consolidation of learning

Answer 28

* learning is often so fragile immediately after training, it is necessary to allow processing time - period known as consolidation to make it permanent * sleep has a critical role in the consolidation of perceptual learning * depriving subjects of slow-wave sleep and rapid eye movement sleep nulifies learning on perceptual tasks * critical time window for consolidation is less than 30 hours after training on a perceptual task ## Footnote * sleep identified through different levels (cyclic way) * disrupt sleep during REM or slow wave period - retaining of perceptual learning during the way is completely gone: learning vanishes * in order for learning to remain over time, sleep has to happen within 30 hours

Question 29

2 models for consolidation during sleep

Answer 29

1. synaptic homeostasis model - slow-wave sleep scales down strength of all synaptic connections excessively strengthened by learning during wakefulness, leaving only synapses strengthened most by learning after sleep 2. reactivation model - neurons involved in learning during wakefulness are reactivated during sleep to strengthen neural connections

Question 30

the role of attention in perceptual learning

Answer 30

* the role of attention in perceptual learning is not completely understood * there is controversy over whether attention to the feature to be learned is necessary for perceptual learning to occur * to understand the role of attention in perceptual learning, we have to distinguish between: perceptual learning with top-down attention; perceptual learning with bottom-up attention; perceptual learning as a result of exposure to a stimulus

Question 31

perceptual learning with top-down attention

Answer 31

* practicing one task did not improve performance in the other task, event though both task used exactly the same visual stimuli * top down attention to the features that are relevant for performing the task appear essential for producing perceptual learning ## Footnote * grid, target stimulus with different orientation * is there a target in that grid? * long edge horizontal or vertical? * told which task to perform * train on local but switch to global: no transfer, top-down attention

Question 32

perceptual learning with bottom-up attention

Answer 32

* recorded VEPs in visual cortex while an awake mouse passively viewed a flickering grating over consecutive days * repeated presentations of grating stimuli of a single orientation resulted in a persistent enhancement of visual evoked potentials in mouse cortex * response potentiations developed gradually over the course of several training sessions and was specific to the orientation of the test stimulus * these results dont dupport the hypothesis that top-down attention is essential for perceptual learning, but suggest that bottom up attention may have a role to play

Question 33

perceptual learning after passive exposure to a stimulus

Answer 33

1. test stage: 5% or 10% coherent motion in 1 of 8 different directions 2. exposure stage: repeated presentation of 5% coherent motion direction, while performing a letter identification task centrally to engage subjects' attention 3. same as number 1 * exposure improved the accuracy with which subjects identified the direction of exposed motion when it was above the threshold of visibility * the authors claim that a frequently presented visual feature sensitises the visual system for learning, even when the stimulus is not relevant or salient * this work led to the concept of task irrelevant perceptual learning

Question 34

What is the aim of the lecture on perceptual learning?

Answer 34

To understand the neural mechanisms of perceptual learning.

Question 35

What are the main learning objectives of this lecture?

Answer 35

1. Understand how visual information is represented in the visual cortex and read-out to form decisions. 2. Evaluate evidence that perceptual learning changes visual representation in the cortex. 3. Evaluate evidence that perceptual learning changes the way visual information is read-out to form decisions.

Question 36

How is visual input represented in the brain?

Answer 36

Visual input is represented at different levels of the cortical visual hierarchy.

Question 37

What brain areas decode neural signals in the visual cortex to make decisions?

Answer 37

Lateral intraparietal (LIP), frontal eye fields (FEF), and prefrontal cortex (area 46)

Question 38

What does the typical neural model of visual discrimination involve?

Answer 38

A population of neurons encodes the visual input and projects onto a single output, which determines behavior

Question 39

How do neurons represent visual input?

Answer 39

by the pattern of firing across a population of neurons

Question 40

What does perceptual learning potentially change in the brain?

Answer 40

Either the representation of visual stimuli in the visual cortex or the read-out by decision-making brain areas

Question 41

What is an alternative explanation for the specificity of perceptual learning?

Answer 41

It could indicate changes in how visual information is read-out rather than how it is represented

Question 42

How can perceptual learning change neural representations?

Answer 42

By altering individual neuron responses, tuning preferences, tuning function width, slope, or response amplitude

Question 43

What did Schoups et al. (2001) find about perceptual learning?

Answer 43

Improvement in orientation discrimination correlated with subtle changes in orientation tuning curves in primary visual cortex

Question 44

What did Ghose et al. (2002) conclude about perceptual learning?

Answer 44

There were no significant changes in tuning curves in V1 or V2 despite improved discrimination performance

Question 45

What did Yang & Maunsell (2004) find regarding extrastriate cortex (V4)?

Answer 45

Neurons in V4 at trained locations had stronger responses and narrower tuning curves.

Question 46

What role do correlated neuronal responses play in perceptual learning?

Answer 46

Changes in correlated responses among neurons may enhance information encoding

Question 47

What did Gu et al. (2011) discover about perceptual learning in the MST area?

Answer 47

Training weakened correlated responses in MST neurons but did not fully account for perceptual learning.

Question 48

How does perceptual learning optimise read-out?

Answer 48

By giving more weight to neurons providing the most reliable information

Question 49

What did Law & Gold (2008) demonstrate about perceptual learning?

Answer 49

LIP neurons became more responsive to visual motion, while MT neurons remained stable, suggesting learning affects read-out rather than representation

Question 50

How does learning a new task affect previously learned tasks?

Answer 50

Training on one task can alter the causal contribution of a brain area to another related task without changing visual representation.

Question 51

What did Chowdhury & DeAngelis (2009) show regarding task learning?

Answer 51

After training on fine depth discrimination, inactivating MT no longer affected coarse or fine depth discrimination but abolished direction discrimination.

Question 52

What is the overall conclusion regarding perceptual learning?

Answer 52

Learning changes how visual information is read-out rather than how it is represented in the visual cortex, explaining perceptual improvements

Question 54

the visual field range

Answer 54

* the full horizontal range >180 degrees * horizontal range in one eye is 160 degrees * vertical range in 135 degrees

Question 55

mapping the visual field

Answer 55

* visual field test uses static or kinetic perimetry to detect dysfunction in central and peripheral vision caused by various medical conditions * present static light target of different intensity at different intensity at different positions in visual field (static perimetry) or moving light towards centre of vision from periphery (kinetic perimetry) * determine threshold for detecting light at different positions or visualfield sensitivity boundaries

Question 56

lesion of right optic nerve causes

Answer 56

total loss of vision in right eye

Question 57

bilateral hemianopia

Answer 57

lesion of optic chiasm causes loss of vision in temporal halves of both visual fields

Question 58

contraletral hemianopia

Answer 58

lesion of optic tract causes complete loss of vision in opposite half of visual field

Question 59

upper contraleral quadratic anopia

Answer 59

lesion of optic radiation (Meyer's loop) causes loss of vision in upper quadrant of opposite half of visual field of both eyes

Question 60

partial lesions of visual cortex lead to

Answer 60

partial visual field deficits on opposite

Question 61

damage to primary visual cortex can cause cortical blindness

Answer 61

* lesions that destroy V1 cause dense cortical blindness by depriving cortex of bottom-up sensory information * BUT cortical blind individuals dont lose all visual abilities within their blind field * some patients have residual sensitivity without consciousness = blindsight * residual visual functions vary considerably among cortically blind patients, most likely due to amount and location of damage * despite residual visual processing abilities in blind field, cortically blind patients still severely impaired at everyday visual functions such as reading and navigating in unfamiliar environments * these visual impairments are primarily responsinle for the significant decrease in quality of life reported

Question 62

prosopagnosia

Answer 62

* cannot identify faces, even familiar ones, but can recognise a face as a face * acquired and congenital forms exist * lesion site is fusiform gyrus, predominantly in right hemisphere * no therapies have demonstrated lasting real-world improvements

Question 63

cerebral akinetopisa

Answer 63

* lose ability to perceived visual motion following lesion to extrastriate cortex * V5 or MT+ * motion blindness from damage to dorsal stream

Question 64

visual agnosia

Answer 64

impaired ability to visually recognised objects (apperceptive and associative) caused by damage to ventral stream

Question 65

cerebral achromotopsia

Answer 65

colour blindness caused by damage to cortex in ventral stream

Question 66

balints syndrome

Answer 66

* inability to perceive the visual field as a whole * difficulty in fixating the eyes * inability to move hand towards objects under visual guidance

Question 67

phase 1 after brain injury

Answer 67

* primary insult or injury, typically including: * direct tissue damage * impaired cerebral blood flow * impaired metabolic activity * leading to edemea dormation * cytoarchitecture changes

Question 68

phase 2 after brian injury

Answer 68

* secondary injury, setting in motion a cascade of pathophysiological processes, including * loss of cell homeostasis * calcium and sodium ion release * neurotransmitter release * excitoxicity * breakdown of blood-brain barrier

Question 69

2 stage process to recovery from acquired brain damage

Answer 69

1. spontaneous recovery 2. training-induced recovery

Question 70

spontaneous recovery | plasticity after acquired visual brain injury

Answer 70

* recovery that occurs in the absence of training or rehab & can be "true" recovery or compensation * injury resolution within 3-6 months after injury * diachisis reversal * changes in kinematics * cortical reorganisation

Question 71

diachisis reversal

Answer 71

inflammation, blood flow, metabolic changes begin to subside

Question 72

changes in kinematics

Answer 72

compensatory eye movements towards affected hemifield

Question 73

cortical reorganisation

Answer 73

within-area and between-area rewiring of brain circuits

Question 74

training induced recovery | plasticity after acquired visual brain injury

Answer 74

* recovery that occurs as a result of training and rehabilitation and is considered compensation * compensatory plasticity from 6 months after injury * recruitment * retraining

Question 75

recruitment | training induced recovery

Answer 75

brain areas not involved pre-injury contribute to function post-injury

Question 76

retraining | training-induced recovery

Answer 76

training of residual brain areas, cortical reorganisation, and compensation

Question 77

spontaneous plasticity after damage to primary visual cortex

Answer 77

* damage to V1 (like damage to any part of the brain) is usually followed by some amount of spontaneous recovery * in visual field deficits, 50-60% probability of spontaneous visual improvements in first month after lesion, but little improvement after 3 months and none after 6 months * most of the spontaneous recovery is thought to be due to reduction in inflammation and edema around the lesion and reactivation of partially damaged tissue near the lesion * patients compensate for vision loss with gaze strategies that are both normal and abnormal and biased toward the affected hemi-field

Question 78

training-induced plasticity after visual brain damage

Answer 78

* visual restoration therapy (VRT) * requires ppts to detect bright light on monitor in one of 500 locations on border between blind and sighted fields * showed that detection accuracy improves with training and reduces size of blind field and increases size of visual field (Kasten et al., 1998) * failed to be replicated - patients trained on the VRT detection task learned to make small rapid eye movements towards the targets to be detected (Reihnard et al., 2005) * more recent work - adults with stroke-induced damage to V1 learned to discriminate global direction of random dot motion coherence (Huxlin et al., 2009) * initially, they could not detect visual stimuli in blind field and were unable to discriminate global motion direction * after training at single location, recovered ability to discriminate global motion and visual recovery generalised to contrast sensitivity and motion

Question 79

potential mechanisms of training-induced visual recovery after V1 damage

Answer 79

* training induces plasticity in spared cortex proximal to lesion * training strengthens neural pathways that bypass V1 and project to extrastriate cortex * training recruits or inhibits visual areas in the intact hemisphere

Question 80

responsiveness of spared islands of cortex within V1

Answer 80

* spared of islands of cortex in V1 could mediate blindsight * individual variability on how visual input drives spared cortex

Question 81

training induces plasticity in spared cortex proximal to lesion

Answer 81

* lesion in left hemisphere * present flashing checkboards: expanding and contracting * some part that was still spared * trained to detect some changes in luminance * over sessions, ability to correctly detect improves * look at islands that are still spared to improve with the left hemisphere deficits

Question 82

visual discrimination training recovers visual functions in chronic cortically-blind fields | Barbot et al. (2021)

Answer 82

* train the participant until they reach top performance at that specific location of the visual field, and then they move the training area further into the scotoma * when we compare the intact hemifield in grey and the damaged before and after training the performance in the latter condition, following training, is largely the same as the intact hemifield * true also for motion discrimination tasks * almost all show improvement at the edges of the scotoma, even though some subjects instead show blue colours, which means a loss of sensitivity ## Footnote Again, as a reminder and to ensure that data and results are valid, it’s important to note that measures were made in the lab using eye trackers to control for eye movements, so there’s no change in ocular motor strategy that underlie these results.

Question 83

training strengthes neural pathways that bypass V1 and project to extrastriate cortex

Answer 83

* Huxlin et al. (2009) studied one patient (VC3) who had a complete V1 lesion * before training, VC3 could point to and detect, but not discriminate, visual motion in the upper right quadrant of his blind field * over 80 training sessions, they recover visual motion discrimination in his blind field, suggesting that recovery did not involve residual V1 * training probably recruited functions in pathways that bypass V1 and project to extrastriate cortex

Question 84

training recruits or inhibits visual areas in the intact hemisphere

Answer 84

* some ev that visual areas in intact brain hemisphere have a role in residual and trained vision in blind field (Henriksson et al., 2007) * 61yo patient with homonymous hemianopia trained on flicker detection in blind hemifield * extensive damage in occipital lobe, including V1 * training started 22mths after stroke, twice weekly for 2yrs * at the start of training MEG field patterns from blind hemifield abnormal, but very similar to the unaffected hemifield by end of training * fMRI used to localise where in cortex changes have taken place * after training, visual info from both hemifields was processed mainly in the intact hemisphere * activity remapped to intact hemisphere in V5, V1, V2, V3 and V3a * images show axial and sagittal slices * ipsilateral representation of the blind hemifield occurs across several visual areas, including V1 * intensive training can induce cortical re-organisation across cerebral hemisphere