From Perception to Consciousness
Lectures Summary Interim 1
Inhoud
Lecture 1 – The Retina ............................................................................................................................ 2
Lecture 2-3-4 – Visual Cortex ................................................................................................................ 30
Lecture 5 – Perceptual Organisation..................................................................................................... 83
Lecture 6 – Are Faces Special? ............................................................................................................ 112
Lecture 7 – Object Recognition ........................................................................................................... 126
Lecture 8 – Action ............................................................................................................................... 141
,Lecture 1 – The Retina
Rods and Cones sample the image
The retina pre-processes the rod an cone signals via bipolar cells to ganglion cells.
,The ganglion cells pass the pre-processed signals to the brain.
So, the retina is already processing the visual information.
Rods and cones are sensitive to different wavelengths. You’ve got red, green, and blue cones.
Although the red cones are more sensitive to yellow.
Rods also have sensitivity to certain wavelengths.
Rhodopsin (a protein) translates light into the closing of Na+ channels so that the membrane
hyperpolarizes > neural signal that is sent to bipolar > ganglion cell.
, Different versions of Rhodopsin (or photopsin) are sensitive to different wavelengths. Many varieties
in animal kingdom. Humans have 4 types (3 for cones, 1 for rods), goldfish and many birds have 5,
dogs and mice 3, etc.
The proteins have different shapes which makes them sensitive to different wavelengths.
When the channel closes, hyperpolarization happens.
The channels are open when there’s no colours.
(photoreceptors don’t have action potentials, meaning they don’t fire. Instead they have a
graded potential.)
Dogs can’t tell the difference between orange balls and green grass.
Rhodopsin changes it shape depending on colour.
Retinal Colour Blindness: Absence of a particular cone type
Colour blindness among humans is not
uncommon. In males 8 out of 100 Caucasians, 5
out of 100 Asians, and 3 out of 100 Africans are
colour blind. The probability is 10 times less in
females. There are many tests to assess colour
blindness. One of the best known is the Ishihara
plates. People with normal colour vision see an
8 here.
Colour vision seems to be present for the whole visual field, yet cones are almost exclusively
confined to the central part of the visual field
(the fovea)
This means that in the periphery, colour discrimination is actually a lot worse.
Although, rods are more present in the periphery than cones.
Lectures Summary Interim 1
Inhoud
Lecture 1 – The Retina ............................................................................................................................ 2
Lecture 2-3-4 – Visual Cortex ................................................................................................................ 30
Lecture 5 – Perceptual Organisation..................................................................................................... 83
Lecture 6 – Are Faces Special? ............................................................................................................ 112
Lecture 7 – Object Recognition ........................................................................................................... 126
Lecture 8 – Action ............................................................................................................................... 141
,Lecture 1 – The Retina
Rods and Cones sample the image
The retina pre-processes the rod an cone signals via bipolar cells to ganglion cells.
,The ganglion cells pass the pre-processed signals to the brain.
So, the retina is already processing the visual information.
Rods and cones are sensitive to different wavelengths. You’ve got red, green, and blue cones.
Although the red cones are more sensitive to yellow.
Rods also have sensitivity to certain wavelengths.
Rhodopsin (a protein) translates light into the closing of Na+ channels so that the membrane
hyperpolarizes > neural signal that is sent to bipolar > ganglion cell.
, Different versions of Rhodopsin (or photopsin) are sensitive to different wavelengths. Many varieties
in animal kingdom. Humans have 4 types (3 for cones, 1 for rods), goldfish and many birds have 5,
dogs and mice 3, etc.
The proteins have different shapes which makes them sensitive to different wavelengths.
When the channel closes, hyperpolarization happens.
The channels are open when there’s no colours.
(photoreceptors don’t have action potentials, meaning they don’t fire. Instead they have a
graded potential.)
Dogs can’t tell the difference between orange balls and green grass.
Rhodopsin changes it shape depending on colour.
Retinal Colour Blindness: Absence of a particular cone type
Colour blindness among humans is not
uncommon. In males 8 out of 100 Caucasians, 5
out of 100 Asians, and 3 out of 100 Africans are
colour blind. The probability is 10 times less in
females. There are many tests to assess colour
blindness. One of the best known is the Ishihara
plates. People with normal colour vision see an
8 here.
Colour vision seems to be present for the whole visual field, yet cones are almost exclusively
confined to the central part of the visual field
(the fovea)
This means that in the periphery, colour discrimination is actually a lot worse.
Although, rods are more present in the periphery than cones.
