Lateral view

Retinogeniculate visual pathway

Ventral view

optic nerve

optic chiasm

optic tract

LGN

optic radiation

primary visual cortex

Retinogeniculate visual pathway

verticalmeridian

horizontalmeridian

fixationpoint

blindspot

foveaoptic disc

Left eye visual field Right eye visual field

Lateralization

Visual field deficits

R optic nerve damage

Puncture in lower temporal retina of right eye

Cut right optic tract

LE VF RE VF

Lateral Geniculate Nucleus (LGN)

LGN1

23

45

6

Retina LGN

Parallel pathways

Midget (parvocellular)

Parasol (magnocellular)

magno

parvo

LGN retinotopic map

LGN physiology

Center-surround receptive field

+−

electrode

V1

V2

V3

V4

V3a

V7

Primary visual cortex (V1)

V1 physiology: orientation selectivity

Neu

ral r

espo

nse

(spi

kes/

sec)

Stimulus orientation (deg)

V1 physiology: direction selectivity

Simple cell

No stimulus in receptive field, no response

Non-preferred stimulus, no response

Orientation selectivity theory

Preferred stimulus, large response

Simple cell sums LGN inputs

Complex cell

Length summation in simple cells and complex cells

Hypercomplex cell

V1 physiology

Simple cells:• orientation selective• some are direction selective• some are disparity selective• monocular or binocular• separate ON and OFF subregions• length summation(best response to long bar)

Complex cells:• orientation selective• some are direction selective• some are disparity selective• nearly all are binocular• no separate ON and OFF subregions• length summation

Hypercomplex cells:end-stopping (best response to short bar)

Hubel & Wiesel movie