chapter 13 Flashcards by Cambell Meier

Occipital lobe is

posterior within the brain, and its major function is vision

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Occipital lobe contains many distinct

visual areas

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visual areas extend into the

temporal and parietal lobes

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Primary visual cortex (V1) surrounds the

calcarine sulcus and contains distinct layers and sublayers

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Within V1, “blobs”

process color information

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the cells between the blobs process

form and motion

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Thin stripes are involved in

color perception

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Thick stripes process

form information

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Pale stripes are involved in

motion perception

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Color perception enhances our ability to

detect form and motion

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Visual processing starts in

V1 and projects to all major visual areas

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V2 is the

secondary processing location, and it also projects onward to major visual areas

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V1 projects through V2 projects to

Dorsal stream, Ventral stream, STS stream

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STS stream

object perception and motion perception

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Ventral stream

object perception and motion perception

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Dorsal stream

visual guidance of movement

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V1 and V2 seem to be heterogeneous general areas processing

all types of visual information

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Higher visual areas are more

specialized but can still integrate information from multiple aspects of vision

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processes dynamic form, or the shapes of objects in motion

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predominantly processes color information

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involved in motion processing; also known as MT

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Damage to these higher visual areas results in

deficits specific to the functions of those areas

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People with damage to V1 report being

blind, but smaller projections from subcortical areas to higher visual areas provide some limited vision

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visual ventral pathway contains two parts,

one on the lateral surface and the other on the ventral surface of the temporal lobe

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Visual streams project to many higher visual areas throughout the

temporal, parietal, and frontal lobes, and these areas seem to have specific functions, although they interact

The lateral ventral pathway may be related to

language and tool use, so may be unique to humans

Lateral occipital region

object analysis

fusiform face area

face analysis

Extrastriate body area

body analysis

fusiform body area

body analysis

superior temporal sulcus

analysis of biological motion

superior temporal sulcus (posterior)

moving body analysis

Parahipocampal place area

analysis of landmarks

ventral stream regions (7)

LO, FFA, EBA, FBA, STS, STSp, PPA

dorsal stream regions

LIP, AIP, VIP, PRR, IPS

lateral intraparietal sulcus

voluntary eye movement

anterior intraparietal sulcus

object direct grasping

ventral intraparietal sulcus

visuomotor guidance

parietal reach region

visually guided reach

intraparietal sulcus

object-direct action

Dorsal stream regions (5)

LIP, AIP, VIP, PRR, IPS

Visual processing is necessary to direct

specific movements

directing specific movements can be done

with or without attention and awareness

Processing visual information about a moving target in order to catch it requires

the interaction of multiple visual areas, largely in the parietal lobe and part of the dorsal stream

When you look at an object, your visual system focuses on

only part of that object

When looking at a face, an observer focuses on the

eyes and mouth, particularly in the left visual field

This bias to the left visual field seems to be specific for viewing

Faces

When a subject performs a mental rotation task, the task is often accompanied by

eye movements

egocentric space

object in relation to the observer

allocentric space

objects in relation to each other

Vision’s primary function is to guide

movement, not to recognize objects

Information for visually guided movement projects from

V1 to parietal areas over the dorsal stream

Patient with damage to the lateral occipital area could

shape their hand to grasp an object they could not consciously see

Patients with dorsal stream damage can

see objects but cannot accurately reach for them

Dorsal stream provides

real-time visual control of action

Posterior parietal visual neurons are active only when the brain is

acting on visual information

Information about shape, movement, and location is sent to the

parietal lobe over different pathways

Parietal-cortex lesions that impact visual areas are typically characterized as

visuospatial or visuomotor

When asked to detect motion, area

V5 showed increased activity

When asked to detect color, area

V4 showed activity

Left side of each retina projects to the

left hemisphere

and right side of each retina projects to the

right hemisphere

Information from both eyes about a particular location in space is combined in

If a visual disturbance affects both eyes, the disturbance must be in

Visual disturbances that affect information from only one eye must occur at

the level of the eye, the retina, or the optic nerve

Damage to the visual cortex typically spares information from the

central part of the visual field (macular sparing)

Reason for macular sparing

could be because the region of the visual cortex corresponding to macular vision receives blood from multiple cerebral arteries, making a stroke in that area less likely

Scotomas

small blind spots that are often unnoticed because the eyes are constantly moving and the brain fills in the blind spots with information from the previous position of the eyes

A complete lesion of area V1 in the left hemisphere results in

hemianopia affecting the right visual field

A large lesion of the lower lip of the calcarine fissure produces a

quadrantanopia that affects most of the upper-right visual quadrant

A smaller lesion of the lower lip of the calcarine fissure results in a

smaller injury, a scotoma

Cortical blindness occurs when a patient has no

conscious awareness of visual stimuli but can accurately indicate locations, directions, forms, or colors of the stimuli

Following damage to area V5, patient was unable to

detect motion

Following damage to area V5, patient was unable to detect motion Pouring fluids was difficult because she could not see the level rise in the cup Interacting with people was disturbing because she could not see them move Vision was otherwise normal brain processes the movement of a form separate from

the form itself

Visual agnosia

is the inability to recognize objects or pictures of objects—or the inability to draw a copy of the objects

Optic ataxia

a deficit in visually guided movements, such as reaching

Optic ataxia Associated with damage to

posterior parietal lobe

Prosopagnosia

the inability to recognize familiar faces

Alexia

difficulty reading

Apperceptive agnosia is an object agnosia in which the patient fails to

recognize a basic feature of the object, such as color or motion

In simultagnosia

the patient is able to perceive an object, but is unable to perceive more than one object at a time

Apperceptive agnosia , simultagnosia typically result from

bilateral damage to the lateral aspects of the occipital lobe

associative agnosia

patient can perceive the object, but they cannot recognize the object

Associative agnosia is typically associated with damage to the

ventral stream

Prosopagnosia patients Rely on recognizing a person based on the

sound of their voice, their hair, or the way they walk

Alexia is the inability to read Associated with damage to the

left fusiform gyrus and lingual area

Left hemisphere is specialized to combine

letters to form words

Alexia can be considered a

visual agnosia where the patient is unable to combine parts (letters) into a whole (words)

Visualization is important to

problem solving and other thought processes

Research suggests that imagery results from

top-down activation of visual areas, and may be initiated by prefrontal areas

Mental rotation of visual images uses

ight-hemisphere dorsal stream areas