unit 2c

Question 1

Sensation

Answer 1

the 1st stage in the func. of the senses, starting w/ info @ the peripheral sensory receptors

Question 2

Perception

Answer 2

the process of recognizing, organizing, & interpreting sensory info

Question 3

Dorsal Visual Pathway

Answer 3

made up of multiple visual areas, it is 1 of 2 main visual processing streams after primary visual cortex (V1).

Involved in perception for ACTION

Question 4

Ventral Visual Pathway

Answer 4

made up of multiple visual areas, it is 1 of 2 main visual processing streams after primary visual cortex (V1).

Involved in perception for RECOGNITION

Question 5

Cortical magnification

Answer 5

a property of sensory & motor syst. in which 1 part of a topographical rep. is larger than the rest, producing a region w/ higher acuity (better sensitivity) in the magnified region.

In the visual system, cortical magnification describes how many neurons in an area of visual cortex are ‘responsible’ for processing stimulus , as a func. of visual files location.

In center of visual field, corresp. to center of fovea of retina, a v large number of neurons processes into f/ small region of the visual field. If same stimulus is seen peripherally, it would be processed by much smaller # of neurons. Incr. # of neurons devoted to processing central vision helps make our central vision more sensitive than peripheral vision.

Magnification of central (ex: foveal) is achieved in steps along the visual pathway, starting in fovea w/ densely packed cones + midget retinal gang. cells of parvocellular pathway & contin. to large region of cortex that received info f/ central vision.

Ex: Expansion of face & hand representations in somatosensory + motor cortical regions. (Have sensitive touch + ^ motor ctrl)

Question 6

Blindsight

Answer 6

a phenomenon where ppl who are perceptually blind demonstrate some response to visual stimuli (bc only part of visual syst. is impaired, other parts- involved w/ motion perception- may still func.

Question 7

Visual agnosia

Answer 7

a disorder in which the patient suffers f/ inability recognize + identify obj., features of objects or scenes, faces or persons despite having knowledge of charact. of the objects, senses, faces or persons.

Can be loosely divided into 2 types by severity: Apperceptive & Associative

Question 8

Apperceptive visual agnosia

Answer 8

disorder characterized by inability to name, copy, or recog. visually presented objects.

Shape perception + figure-ground segregation is impaired, but basic visual func (color, luminance, disc., visual acuity) & object identification based on non-visual cues are preserved.

Question 9

Associative visual agnosia

Answer 9

a disorder in which visual object recog. is impaired (ex; naming of visually presented obj., categorization, matching by func.) but elementary visual perception is more or less preserved.

This is how object agnosia is typically described, as this is more common.

Question 10

Visual object agnosia

Answer 10

a disorder in which visual object recognition is impaired ( ex; naming visually presented objects, categorization, matching by function) but elementary visual perception is more or less preserved. (matching. copying of visually presented obj., drawing objects from memory, and non-visual obj. recognition.

Question 11

Fusiform face area

Answer 11

a bilateral visual processing area that is thought to specialize in face processing (argued)

Dam to this area can cause face perception deficits.

Question 12

Prosopagnosia

Answer 12

a disorder in which faces can’t be recognized, but other forms of obj. recog. are unimpaired

• Apperceptive & Associative(amnesic)

Question 13

Apperceptive (Prosopagnosia)

Answer 13

problems w/ recognizing a face v. other objects (CANT tell by vision alone whether something is a face or not)

Question 14

Associative (amnesic) type [Prosopagnosia]

Answer 14

problems w/ recog. FAMILIAR faces
(can tell its a face BUT NOT whose face it is)

Question 15

Capers syndrome

Answer 15

delusional belief that an acquaintance has been replaced by doppelgänger.

Its 1 of delusional misidentification syndromes more common in schizo., dementia, & brain trauma. May arise f/ abnormal emot. response to faces → disconnect b/t temporal & limbic cortex; possible ex. of really high -oder face processing issue

Question 16

Fregoli syndrome

Answer 16

delusional belief that diff. ppl are a single person, who changes appearance/disguise

Generally viewed w/ paranoia (“shapeshifting” person out to get them). Rare delusional misidentification syndrome.

Appears to arise f/ damage to left frontal + right temporoparietal regions, possibly due to disconnec. b/t hemispheres, that affect high-order face processing.

Patients may inaccurately recall places, objects, events→ theory that associations among stored memories may be messed up - w/ image of one face (or objects) ending up being improperly assoc. w/ another one

Question 17

Simultagnosia

Answer 17

a deficit in scene perception, w/ normal visual fields + normal lower-lvl (elementary) visual perception.

Svrl theories proposed to account for simultagnoisc symptoms: some focus on disruption of specific process, such as speed of attentional processing, others focus on the disruption of representational structure

2 kinds : DORSAL & VENTRAL

Question 18

Dorsal Simultagnosia

Answer 18

deficit in scene perception, where patient an only preserve 1 stimulus at a time (more severe)

Question 19

Ventral simultagnosia

Answer 19

deficit in scene perception, where patient can see mult. objects, but can’t recog. them (can navigate + count, BUT can’t read)

Question 20

Central/Cerebral Achromatopsia ( AKA Cortical color blindnes)

Answer 20

impairment of color vision in entire visual field

arises f/ cortical lesions on the VENTRAL SURFACE OF TEMPORAL-OCCIPITAL LOBES.

Loss of color vision in full visual field is rare, as lesions would need to affect color processing in BOTH hemispheres

2 kinds: HEMIACHROMATOPSIA & TRANSIENT ACHROMATOPSIA

Question 21

Hemiachromatopsia (C. Achromatopsia)

Answer 21

Loss of color vision is restrict. to one half of visual field. Rest of visual field has normal color visions
(color vision can even be lost for 1 quarter of visual field)

Question 22

Transient Achromatopsia (C. Achromatopsia)

Answer 22

temp. loss of color vision in any part of visual field, usually from a TIA (transient ischemic attack)

Question 23

Akinetopsia

Answer 23

Inability to perceive motion that arises f/ damage to V5/MT-the area of cortex resp. for visual motion: patients exp. a strobe-light effect of vision.

Can be caused by damage such as stroke, trauma, & rarely f/ some antidepressants.