Vision And Touch Flashcards
Bundle?
Optic nerve
Resulting in gap in receptor layer - blind spot
Fovea
Centre of retina
High acuity vision
Two receptors in the retina
Rods - faint light
Cones - bright light
After optic chiasm…
Signals go through thalamus, and then to the primary visual cortex
Without eye movement, retinal images disappear after a few seconds … Why
Neurons in the visual system respond to change rather than steady input
How does colour vision work?
Wavelength between 400 and 700 nm are visible for humans
Component processing/trichromatic theory
3 types of cones
The photopigment in each cone makes it responsive to short/medium/long wavelengths
Perceived colour depends on activity of these 3 cones
Opponent processing?
Neurons respond in opposite directions to complementary colours
At all levels of visual pathway except for receptors
Explains why complementary colours can’t exist together
Colour blindness
Deficiency/absence of photopigments responsive to certain wavelengths
Most are red or green
X chromosome
Ishihara test
Briefly explain the eye
Light enters through Pupil
Regulated through iris
Through lens
Onto retina (which turns everything upside down)
Dorsal stream
‘Where’ stream, perception of where things are
Damage- still possible to describe an object, problems to imagine a location or recall it from memory
Ventral stream
‘What’ stream
Damage - difficulties to fully describe an object and imagine it
Binding problem idea 1
Sensory info converges into areas sensitive for more complex stimulus
However enviro too complex for each Neuron to have a single object
Binding problem idea 2
Binding requires simultaneous activity in brain/neurons involved in processing
Sensory pathway 1
Touch
Axons cross over side of brain stem, to thalamus
Most protect primary SI
