Ch 3 - Spatial frequency + receptive fields in striate cortex

Minimum Discriminable Acuity

he smallest angular difference (size, position, or orientation) in a feature that the human eye can distinguish.

vernier acuity

ability to discern the smallest misalignment between lines

visual performance

resolution is 10 times finer than the smallest details detected by the retinal cones.

otto schade’s experiment

He explored how changes in the contrast of these stripes affect our ability to detect them.

Spatial Frequency

The number of cycles (repetitions) of a pattern per degree of visual

what does high spatial frequency mean?

more cycles in a given angle

orientation tuning

the tendency of neurons in striate cortex to respond optimally to certain orientations and less to others

selective responsiveness to line or edge at just the right orientation.

hardly at all when line is tilted more than 30 degrees from optimal orientation

ocular dominance

property of the receptive fields of striate cortex neurons by which they demonstrate a preference

what does ocular dominance respond more rapidly to?

when a stimulus is presented in one eye than the other

what do humans have lower visual acuity and contrast sensitivity to than horizontal/vertical targets

oblique targets

cortical cells

like retinal ganglion cells, they respond best to grating that have just he right spatial frequency to fill the receptive field center

simple cells

cortical neurons whose receptive fields have clearly defined excitatory and inhibitory regions

when is an edge detector most highly excited

when there is light on one side of its receptive field and darkness on the otherside

complex cells

cortical neurons whose receptive fields do not have clearly defined inhibitory regions

WILL respond regardless where a stripe is present as long as somehwere on cell’s receptive field