Week 2 - Visual perception: from photons to phenomena Flashcards
(31 cards)
What is the primary function of the Parvocellular (P) Pathway?
Sensitive to colour & fine detail
Most input comes from cones and helps us see fine details and identify objects.
What is the main difference between the Parvocellular (P) Pathway and the Magnocellular (M) Pathway?
P pathway is for fine detail; M pathway is most sensitive to motion
P pathway has low temporal resolution, while M pathway has high temporal resolution.
What is the pathway from the eye to the brain?
Retina, Optic nerve, Optic chiasm, Lateral geniculate nucleus (LGN), Cortical V1
This pathway transmits visual information to the brain.
What is retinotopy?
Things that are near to each other in space are processed in cells that are physically near to one another.
What does lateral inhibition do?
Reduction of activity in one neuron caused by a neighbouring neuron
This is useful for enhancing contrast at the edges of objects.
What is the role of the Lateral Geniculate Nucleus (LGN)?
Part of the thalamus, a subcortical relay for sensory input & motor output
It maintains a retinotopic map and correlates signals from the retina.
What does the Primary Visual Cortex (V1) extract?
Basic information from the visual scene such as edges, orientations, wavelength of light.
What is blindsight?
Ability to make visual discriminations in blind area despite cortical blindness
This occurs due to other routes from the eye to the brain that are not involved in conscious vision.
What is the geniculostriate route?
The primary visual pathway that transmits visual information from the retina to V1 via LGN
It is essential for conscious visual perception.
What is the Functional Specialisation Theory?
Different parts of the visual cortex are specialised for different visual functions.
What did Zeki’s studies indicate about V4?
V4 is more active for coloured images than greyscale images
It is specialised for colour processing.
What condition is associated with damage to V5/MT?
Akinetopsia
Patients with this condition have deficits in motion perception.
What is the ‘Where’ pathway concerned with?
Movement processing (vision for action).
What is the ‘What’ pathway concerned with?
Colour & form processing (vision for perception).
Fill in the blank: The _______ is the colour centre of the brain.
V4
Fill in the blank: The _______ is the motion centre of the brain.
V5/MT
True or False: Blindsight occurs due to damage to the retina.
False
It occurs due to damage to the brain’s occipital cortex.
What is the significance of Hubel & Wiesel’s single-cell recordings?
Indicate that some cells respond to simple features while others combine those features into complex ones.
What is the Parvocellular (P) Pathway responsible for?
Colour and fine detail; slow processing; high spatial resolution; receives input from cones.
The P pathway is crucial for tasks requiring high visual acuity.
What is the Magnocellular (M) Pathway responsible for?
Motion detection; fast processing; low spatial resolution; receives input from rods.
The M pathway is essential for detecting movement and timing.
What is retinotopy?
The spatial organization of visual input where nearby stimuli are processed by nearby neurons.
Retinotopy allows for the mapping of visual input directly onto the visual cortex.
What is lateral inhibition?
A process where one neuron’s activity inhibits its neighbors, enhancing contrast at edges.
Lateral inhibition is important for visual perception of edges and contrasts.
What is the function of the Lateral Geniculate Nucleus (LGN)?
A relay center in the thalamus that maintains retinotopy and processes contrast and motion.
The LGN plays a critical role in visual processing before reaching the cortex.
What does the Primary Visual Cortex (V1) do?
Extracts basic visual features like edges and orientation; maintains retinotopy.
V1 is the first cortical area to process visual information.
