How the Brain Works The Facts Visually Explained by DK (z-lib.org)

68

BRAIN FUNCTIONS AND THE SENSES

The Visual Cortex 69

IN

TE

RI

OR

CO

RT

EX

Animals such as primates have

a large field of stereoscopic

vision and can judge distances

better than herbivores or most

birds. However, they have a

blind zone behind them that

can be seen only by turning the

head. Animals with eyes on the

sides and top of the head have

a wider field of 2-D vision and

greater all-around awareness.

FIELDS OF VISION

AREAS OF THE VISUAL CORTEX

V1 Responds to visual stimuli.

Passes on information and responds

to complex shapes.

BA

CK

O

F^ B

RA

IN

Registers angles and symmetry and

combines motion and direction.

Responds to color, orientation, form,

and movement.

Responds to movement.

Detects motion in periphery of

visual field.

Involved in perception of symmetry.

Probably involved in processing of color.

V2

V3A, V3D,

VP

V4D, V4V

V5

V6

V7

V8

AREA FUNCTION

THE VISUAL CORTEX

IS VERY THIN—

JUST 0.08 IN (2 MM)

RABBIT HUMAN

Visual field of left eye Visual field of right eye Binocular visual field Blind zone

The visual cortex

Nerve signals progress

through the various layers of

the cortex, each adding more

information to the image. It

takes half a second for the

image to be assessed and

become a conscious perception.

2

V1

V3A

V3D

V2

V2

V4V

V8

V6

VP

V3

V7

V3A

V2

V1

Some visual-

processing areas

curve around back of

brain into groove

between hemispheres

Visual cortex,

located in

occipital lobe

Image formed by brain

after it combines images

from left and right eyes’

visual fields

V4D

BINOCULAR VISUAL FIELD

VISUAL FIELD OF LEFT EYE

VISUAL FIELD OF RIGHT EYE

US_068-069_The_Visual_Cortex.indd 69 20/09/2019 12:33