wk3: ND - Agnosia, Neglect, Dyslexia Flashcards

1
Q

When are the 3 parallel pathways no longer segregated?

A

at the striate cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does damage to the dorsal visual pathway lead to? (symptom)

A

impaired goal-directed “action” (dorsal is “where” pathway)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does damage to the ventral visual pathway lead to? (symptom)

A

Agnosia (inability to perceive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Can patients with visual agnosia see objects? Explain

A

yes, however even though they see the object, they don’t understand what it is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Can patients with visual agnosia copy drawings?

A

No, however they can draw from memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define optic ataxia

A

a high order deficit in reaching (i.e. reaching with their arms) visual goals that occurs with posterior parietal cortex (PPC) lesions. Is a problem with dorsal pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a classic test you can use to test for problems with dorsal stream (optic ataxia)?

A

Hold out an oval with a rectangular slit in it at arms length from the subject and ask them to extend their arm and match the orientation of the slit with their hand and spatially have their arm in the same spatial plane as the slit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do patients with optic ataxia fair with orientation matching?

A

Generally not too much worse than normal. Not too many errors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do patients with optic ataxia fare with spatial matching or “posting”?

A

Much worse. People with optic ataxia make more spatial errors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is “posting”? in the context of the dorsal test in this lecture

A

posting = putting the card in the rectangular slit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are parallel channels integrated into visual processing?

A

carry visual signals from retina into thalamus and thence into cortex (Magno-, parvo- and konio- cellular pathways)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe top-down feedback

A

modulation of afferent signals by processes such as attention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Functional Localisation?

A

Different attributes of each object being processed in different cortical areas; different modalities (e.g. sensory, cognitive) processed independently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 3 parallel pathways from retina to primary visual cortex

A

Magnocellular
Parvocellular
Koniocellular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name 4 other functions of the posterior parietal cortex

A

Central role in directing attention to spatial locations
Helps bind different attributes of an object together
Gating inputs into ventral stream
Important for reading? (dyslexia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How can visual neglect occur?

A

via primary cortex damage. If this occurs, visual neglect will affect the contralateral visual field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

True/False: Visual neglect leads to the same type of constructional disability

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which visual hemifield is visual neglect most common in? Why?

A

Left hemifield. This is because the right parietal cortex controls attention in both hemifields while the left parietal cortex controls attention in only the right hemifield. So if the right parietal cortex is damaged, the other side can’t compensate for the left hemifield.

19
Q

Is there an association between pre-reading phonological skills and reading ability?

A

Yes. Pre-reading phonological skills can predict later reading failure (Goswamy & Bryant, 1990; Richardson et al. 2003)

20
Q

What did Ahissar, Temple, and Breier (2000, 2000, 2002) find dyslexic patients have trouble with?

A

difficulties in discriminating syllables and rapid acoustic stimuli

21
Q

What are the 2 routes in the dual-route model of reading

A

Route A: direct lexical
Route B: phonological

22
Q

What is “Dysphoneidesia” and what proportion of dyslexics have it/are it?

A

Phonological dyslexia. 28%.

23
Q

What did (Castles & Coltheart, 1993, 2004) find in relation to dyslexia and phonology?

A

In some dyslexics, the errors are for irregular words and in others, the impairment is not matched by deficits in phonological awareness

24
Q

What did (Ramus &Szenkovits, 2008; Boets et al., 2013) find in relation to dyslexia and phonology?

A

Phonological representations themselves are normal in dyslexics; it is access to them that is defective

25
Q

What did (Stuart, 1990) find in relation to dyslexia and phonology?

A

Reading affects auditory perception (e.g., r-i-ch, p-i-t-ch)

26
Q

What did (Ehri, 1989; Castro-Caldas et al., 1998; Mann & Wimmer, 2002) find in relation to dyslexia and phonology?

A

Orthographic training (reading) improves phonemic awareness

27
Q

What is MEG?

A

Magnetoencephalography: a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers.

28
Q

Where does activation occur in MEG during reading? (3)

A

Starts in occipital poles at the back on both sides/(visual cortex)
(By 170ms) it extends to the left occipito-temporal region
Then it goes to other areas

29
Q

What is the role of the occipito-temporal region of the brain

A

is the brain’s “letterbox” that extracts word forms from the visual scene

30
Q

Name 4 potential biological deficits in dyslexia

A

Gene translocation on chromosome 6 in the HLA region
Abnormal hemispheric symmetry of the planum temporale?
Neuronal ectopias and architectonic dysplasias located mainly in perisylvian regions and affecting predominantly the left hemisphere
Abnormal magnocellular pathway

31
Q

List 4 magnocellular defects that have been shown in dyslexics

A

Poorer contrast sensitivity at lower spatial frequencies (Lovegrove et al., 1980)
Low contrast stimuli elicit poorer visual evoked potentials (Livingstone et al., 1991)
Magnocellular layers in the LGN are abnormal (Livingstone et al., 1991)

Impaired visual motion sensitivity both psychophysically and in fMRI (Eden et al., 1996).

32
Q

In what contrast would dylexics have poorer visual evoked potentials? Why?

A

Lower contrasts. Low contrast gratings activate only M cells, and the magnocellular pathway is messed with in dyslexics

33
Q

How would you describe learning to read? (as a process)

A

probably a process of training the attentional spotlight to move sequentially along the visual scene.

34
Q

True or False: Visual search mechanisms are random and have memory

A

False. Visual search mechanisms ARE random BUT DON’T have memory

35
Q

On the integrity of what visual pathway does the attentional spotlight depend on?

A

M pathway and dorsal stream. Therefore, any impairment of the M pathway or the parietal cortex can lead to reading problems

36
Q

How well do we expect dyslexics to perform in visual search tasks?

A

poorly

Both attentional engagement and disengagement are poorer in dyslexic children. (Facoetti et al., 2008).

37
Q

What have FMRI studies found in terms of brain activation when reading? (2.5) What does this suggest? (1)

A

poorer activation in temporal lobe and posterior cortical areas concerned with grapheme-phoneme correspondence and phonological processing. – this provides evidence for the classic phonological theory of dyslexia

38
Q

What might FMRI brain activation results for subjects reading be due to? (other than what was concluded) (2)

A

the poorer activation of these areas may be downstream effects due to lack of a fluent temporal sequence of graphemes being shunted into the “letterbox” areas for word recognition and further grapheme-phoneme correspondence.

39
Q

Does reading influence brain structure?

A

There is a correlation that suggests that Left superior longitudinal
fasciculus and the left arcutae fasciculus show correlation of their
size (fractional anisotropy) with reading scores.

40
Q

What is the main role of the Left superior longitudinal
fasciculus and the left arcutae fasciculus?

A

are the two main pathways connecting brain regions involved in reading.

41
Q

Does language exposure change Left superior longitudinal
fasciculus and the left arcutae fasciculus?

A

Yes. Makes profound changes to these tracts [Romeo et al., J.
Neuroscience (2018) ].

42
Q

Define Synesthesia

A

stimulus in one sensory modality (or submodality) causing perception in another sensory modality (or submodality) - e.g. hearing music accompanied by seeing colours

43
Q

What might synaesthesia be due to?

A

may be due to lack of pruning during development between cortical areas processing different modalities or submodalities