Visuoconstructive Functioning

Question 1

Visual Agnosia

Answer 1

Inability to recognize familiar objects not related to loss of visual acuity – familiar objects can be seen but not recognized

Question 2

Prosopagnosia

Answer 2

special case of agnosia in which recognition deficits specific to faces

Question 3

Object Vision Pathway

Answer 3

VENTRAL; primary visual cortex; secondary visual cortex; inferior longitudinal fasciculus; posterior inferotemporal cortex

Question 4

Spatial Vision Pathway

Answer 4

DORSAL; superior longitudinal fasciculus;; posterior parietal lobe

Question 5

Temporal route

Answer 5

important for recognizing objects

Question 6

Parietal route

Answer 6

important for spatial location of objects

Question 7

Monkey Double Dissociation

Answer 7

temporal lobe- impaired time in object discrimination but could do the spatial task
parietal lobe- could not do spatial task as quickly but could do object recognition

Question 8

Methods of Monkey Double Dissociation?

Answer 8

Monkeys had to either learn to choose an unfamiliar object or choose object nearest a “landmark”–> removed parts of brain in either temporal or parietal lobe–> dictated the difficulties in performance

Question 9

Parietal lobe neurons

Answer 9

60% of neurons are responsive to peripheral (non-foveal) parts of visual field–> spatial location

Question 10

Temporal lobe neurons

Answer 10

receptive field always includes fovea; differential sensitivity to various objects; 41% excited by various stimuli, 59% demonstrated selectivity

Question 11

How are objects defined?

Answer 11

object constancy; color & texture; variability in sensory information

Question 12

object constancy

Answer 12

recognize objects in infinite orientations

Question 13

color & texture

Answer 13

even when inappropriate, still able to recognize things

Question 14

variability in sensory information

Answer 14

viewing position; distance from retina (size constancy even though they appear different sizes bc of distance); rarely seen in isolation

Question 15

Viewer centered recognition

Answer 15

perception depends on recognizing objects from a variety of perspectives: stored representations for each perspective, match templates in memory to stimulus

Question 16

Problems with viewer centered recognition

Answer 16

need template for each object, need multiple templates for each object, driven by a single cell (grandmother cells &; gnostic units), loss of cell, novel objects

Question 17

grandmother cells

Answer 17

coined to convey the notion that recognition arises from the activation of neurons that are finely tuned to specific stimuli

Question 18

gnostic unit

Answer 18

type of neuron that can recognize a complex object (Greek “of knowledge”), cell (or cells) signal the presence of a known stimulus

Question 19

object-centered recognition

Answer 19

sensory input gives basic properties: objects defined on relationship among basic properties; major/minor axis

Question 20

object-centered recognition occurs by parts

Answer 20

basic building blocks analyzed; ensemble hypothesis says recognition results from specific combination of core features; explains confusion of visually similar objects; allows for recognition of novel objects

Question 21

geons

Answer 21

attempts to try and define building blocks

Question 22

apperceptive visual agnosia

Answer 22

failure in object recognition with basic visual functions (acuity, color, motion) preserved; difficulty with copying; deficits in object constancy;

Question 23

how to test for apperceptive visual agnosia?

Answer 23

unusual views test; incomplete figures test—> difficulty with perceptual categorization, thus cannot recognize from usual views based on constancy

Question 24

associative agnosia

Answer 24

not attributed to perceptual difficulties; can copy & perform subtle shape discriminations; can perform unusual views test; still can’t name it

Question 25

Warrington Model

Answer 25

left hemisphere systems: semantic categorization & visual analysis; right hemisphere systems: perceptual categorization & visual analysis

Question 26

lesion in left-hemisphere causes?

Answer 26

associative agnosia

Question 27

lesion in right-hemisphere causes?

Answer 27

apperceptive agnosia

Question 28

problem with warrington model

Answer 28

fails to capture difficulty with integration

Question 29

integrative agnosia

Answer 29

to recognize objects, individuals examine each piece in isolation and put together; appears to be a core deficit underlying many agnosias

Question 30

Behrmann et al 2006

Answer 30

These results
suggest that encoding the spatial arrangements of parts of an object requires a mechanism that is different
from that required for encoding the shape of individual parts, with the former selectively compromised in integrative agnosia

Question 31

prosopagnosia

Answer 31

isolated deficits in facial recognition

Question 32

damage causing prosopagnosia

Answer 32

most frequent following bilateral lesions; possible following right lesions; rare following left lesions; tend to be focused in occipital temporal regions