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NEUR3302 > Wk4 Space & Action > Flashcards

Wk4 Space & Action Flashcards

1
Q

perception drives action, but also action__

A

preparation can drive perception

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2
Q

what are basic characteristics of visual information at the primary visual cortex? 2

A

simple features eg. orientation

retinotopic

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3
Q

what are the two ‘sides’ of visual field on the retina in each eye

A

nasal and temporal

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4
Q

what are the two visual pathways from the retina?

A

retinotectal pathway

geniculostriate pathway

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5
Q

which visual pathway would be involved in reflexively detecting sudden visual stimuli?

A

retinotectal pathway (from the retina to the superior colliculus on the tectum/midbrain)

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6
Q

what are the two pathways within the geniculostriate visual pathway? how are they oriented? what type of processing does each concern?

A

magnocellular (Dorsal): fast efficient processing

parvocellular (ventral): slow effortful processing

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7
Q

where does the dorsal stream terminate?

A

parietal lobe

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8
Q

where does the ventral stream terminate?

A

inferior temporal lobe

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9
Q

at what level (biologically and developmentally; 2) do dorsal and ventral streams start?

A

at the retinal level

in place in embryo

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10
Q

what type of cells have been found to diverge into M and P types in macaque monkey embryos?

A

retinal ganglion cells

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11
Q

where are parvo cells found in the retina? how about magno cells?

A 
magno = peripheral
parvo = closer to fovea
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12
Q

How is information from the left and right eyes organised in the LGN, with M and P cells ?

A

M cells connect to two layers of LGN
P cells connect to 4 LGN layers

contralateral and ipsilateral connections are interweaved at each layer, meaning information from both visual fields is combined

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13
Q

midget and parasol cells are a.k.a __

A

parvo cells and magno cells, respectively

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14
Q

what are particular properties of visual information in parvocellular pathway? 4

A

color
high spatial resolution
slower
sustained response

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15
Q

what are particular properties of visual information in magnocellular pathway? 4

A

monochrome
low spatial resolution
faster
transient reponse

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16
Q

which type of visual cells are used more at night?

A

magno cells

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17
Q

which type of visual cells detect higher details? what is the functional property that allows this?

A

parvo

smaller receptive fields

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18
Q

which type of visual pathway cells detect motion better? what is functional property that allows this?

A

magno

larger receptive fields

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19
Q

what type of neurological dysfunction may explain dyslexia? what functional deficit does it explain?

A

reduced mangocellular density in dyslexic autopsies

impaired ability to read and visually flick between bits of information

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20
Q

what could the failure of giving coloured glasses to dyslexics indicate about neurological pathways?

A

we do more with vision than relying either of the M and P pathways

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21
Q

what was a hypothesis about how visual processing could explain social deficits in autistic infants?

A

they might have trouble putting together high and low spatial contrast images of faces due to magnocellular dysfunction, leading to poor social development

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22
Q

at a higher cognitive level, the magnocellular pathway primarily allows us to ___ by coding for ___

A

work out where things are

location

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23
Q

what evidence links selectivity for orientation and visual guided action in macaque studies?

A

neurons in area 7 (parietal) were selectively activate for 45 deg orientation and direction of reach. when lesioned, results were poorly directed reaches

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24
Q

by 64 weeks or 16 months 3 dimensional reach profiles are almost as refined __ . showing?

A

as adults are

selectivity is fine-tuned early in development

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25
Q

lesions in the dorsal stream of cortex can result in __

A

ataxia

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26
Q

symptoms of ataxia

A

inability to use visual info to guide movement of hands with deficits more severe in periphery

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27
Q

why does ataxia result in more sever deficits in the visual periphery, eg picking things up with directly looking at them ?

A

magno cells form the dorsal stream and are located more in the periphery of the retina

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28
Q

in ataxia, or damage to dorsal stream of the cortex, ____ is preserved

A

ability to fixate (foveate)

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29
Q

over or undershooting movements such as reaching for objects is could reflect a diagnosis of ___

A

ataxia (damage to dorsal stream)

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30
Q

what results would a patient with ataxia give on a task where they had to reach and point to a display of lights while only foveating on the central light? 2

A 
smaller range (degrees) of accuracy in pointing to lights 
hypometria or shortened underreaching of the goal
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31
Q

what does the ventral stream largely concern? what type of information processing happens here?

A

‘what’ / gnosis / knowledge

semantic

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32
Q

what is the inferotemporal cortex (a later stage of the ventral pathway) finely tuned to ? what is not tuned to? 3

A

complex shapes

retinal image size, spatial location, and orientation in the picture plane

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33
Q

monkey lesions to inferotemporal cortex produce __ deficits

A

visual discrimination

34
Q

def visual object agnosia

A

impaired recognition of familiar objects through vision

35
Q

what is visual object agnosia not due to? 3

A

loss of low-level visual process (acuity, luminance, colour sensitivity are normal)
general intellectual loss (e.g dementia)
loss of semantic info about objects

36
Q

visual object agnosics are still able to recognise objects __

A

via other modalities like audition (sounds they make) and touch

37
Q

visual agnosics recognise ___ more poorly than __ , and both more poorly than ____

A

line drawings
photographs
real objects

38
Q

a patient with visual agnosia was worse at drawing objects from ___ than from ___

A

a copy

her memory of the object

39
Q

how can dorsal and ventral streams be dissociated in a simple physical task?

A

ventral stream: perceptual matching of the orientation of an aperture with a book-like object
dorsal stream: visuomotor ‘posting’, where the object is put through the angled aperture

40
Q

how does grasping unrecognised objects dissociate visual agnosics and optic ataxics?

A

controls will pick up the object with grasps that centre the mass of the object.
ataxics pick up the object without often centring its mass symetrically
agnosics can pick it up similar to controls

41
Q

what does it suggest that a visual agnosic can successfully grasp an unrecognised object?

A

they can pre-shape their grasp using info from the intact dorsal stream (they still ‘see’ how)

42
Q

where was grasp shaping found to activate in fMRI?

A

parietal lobe / dorsal stream

43
Q

parietal cortex contains the ___ cortex

A

sensory

44
Q

damage to subregions in parietal cortex can distort different ___

A

aspects of body representation

45
Q

in what way is the parietal cortex an association hub? what is combined here? 5

A

all lower and higher level sensory information is combined, including body and object info
vision, audition, touch, kinaesthesis and proprioception

46
Q

somatosensory cortex is the main sensory receptive area for __

A

the sense of touch

47
Q

somatosensory cortex is layed out / organised __

A

proportional to relative density of tactile receptors on each body part

48
Q

what two problems must be solved in making an action?

A

where’s the object?

where are our body parts?

49
Q

def reference frames

A

coordinates / set of axes describing the location of an object relative to body parts

50
Q

initial coding of references frames are based on ___

A

relevant sensory organ (eye, ear, touch)

51
Q

how does coding for reference frames change over time? 2

A

initial coding centred on relevant sensory organ (whatever first picks up the signal; eye, ear, touch)
subsequent coding based on the effector that is to be used to interact with the object (eg hand)

52
Q

what are three things/models a reference frame for an object could be centered against?

A

position of the body, the head, the eyes

53
Q

what 3 areas in the parietal lobe are involved in translating reference frames?

A
  1. parietal reach region (PRR)
  2. lateral intraparietal are (LIP)
  3. anterior intraparietal area (AIP)
54
Q

what particular body part action does the lateral intraparietal area translate coordinates for?

A

saccadic eye movements: activate to immediate as a well as delayed responses

55
Q

what particular body part action does the parietal reach region translate coordinates for?

A

reaching: activates to immediate as well as delayed responses

56
Q

what particular body part action does the anterior intraparietal area translate coordinates for?

A

grasp planning: grasp shaping to different shapes and sizes

57
Q

what is the consequence of depressing activity in the anterior intraparietal area (AIP) with GABA?

A

reaching but no grasp ( grasp shape is distorted)

58
Q

what types of info are inputs to parietal region and are important in transforming reference frames? 6

A 
auditory signals 
visual signal 
eye position 
head position 
limb position
efference copy
59
Q

how would a neurone encoding reference frames differ when a sensory target is eye-centred, compared to head centred? 2

A

eyecentred coordinates involve a shifting and a recalculation activation distributions

60
Q

which parietal regions take info from body-related signals to transform coordinates? 2

A

LIP (lateral intraparietal area)

PRR (posterior reach region)

61
Q

what type of reference frame is necessary for the process of reaching?

A

creating an intermediate reference frame where the coordinates are recalculated relative to a limb

62
Q

how were batista et al 1999 able to demonstrate they had found a neurone encoding reaches to visual targets in an eye-centred reference frame? (study used monkeys pressing a green light and fixating a red light)

A

when hand location remained constant (same light position) and eye movement shifted, the response profile shifted

also, when the hand varied and eye position was constant the response was constant

63
Q

visually guided action is an interaction between ___

A

visual object info and body part perception

64
Q

what does it mean that we develop a sense of agency through actions?

A

we come to learn (as kids) that we cause events in the environment by doing things with our body

65
Q

body representation schemas are essential for __ 2

A

selecting relevant visual info

guide planning and execution of actions

66
Q

sense of self depends on ___ information

A

multisensory

67
Q

sense of self is ___ 3

A

dynamic, malleable, plastic

68
Q

left sided neglect can involve losing representation of both __ 2

A

body parts

environment

69
Q

left-sided neglct happens after ___ lesions

A

right-side parietal lobe

70
Q

what is happening functionally in left-sided neglect?

A

patients fail (or are slow) to process info coming from the left side of environment

71
Q

2 cognitive things happen in left-sided neglect?

A

excessive engagement of attention on items in right-side of space
reduce disengagement of attention away from items in right-side space

72
Q

what are three simple behavioural task that could demonstrate hemispatial neglect? 3
what are the typical results in these tasks?

A

line bisection
line crossing
spontaneous and copied drawings

Ps can only draw or cross the right side of images

73
Q

3 behavioural consequences of left-sided neglect

A

fewer eye movements
altered reaching trajectories to left hemispace
bumping left side of body into obstacles

74
Q

what can eye tracking reveal about visual scanning in hemispatial neglect? 3

A

they make less movements than controls
they gaze very little at the left side
although this improves over time and gaze goes into the left side

75
Q

what does 3d capture of hemispatial neglect patients reveal? 2

A

their reach is curved away from the left and it is less direct than controls

76
Q

def intrinsic spatial coding

A

knowing what our own body parts are doing

77
Q

when is intrinsic spatial coding essential?

A

when a body part is going to be obscured from vision at some stage in movement planning and execution

78
Q

where is intrinsic coding happening?

A

parietal lobe

79
Q

what could happen if sensorimotor integration is affected by damage to unilateral parietal lobe? why?

A

perceive arm and leg of one side to drift and fade when unseen (as in DF case study)
internal representation of the body’s state may not be maintained without vision

80
Q

most out of body experiences are reported when ___ . why?

A 
lying down (eg in a hospital bed) 
the parietal lobe also incorporates visual and gravitational cues (vestibular)

NEUR3302 (7 decks)

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