Sensory Systems Vision And Touch Flashcards
What is perception?
Higher order process of integrating, recognising and interpreting sensation
What’s the hierarchical organisation of sensory processing?
Association cortex Secondary sensory cortex Primary sensory cortex Thalamic nuclei Receptors
How does the eye take in light?
Light enters the eye through the pupil
Light then goes through the lens
Turns everything upside down
How are Neurons arranged?
In layers the receptor cells are the innermost layer
What’s a bundle of axons?
Optic nerve
What’s the fovea?
Specialised for high acuity vision
What’s the blind spot?
Gap in receptor layer
What are the receptors in the retina called?
Ross and cones
What are the rods?
Respond best to faint light
More rods than cones
Come together to make a ganglion cell
What are cones?
Respond best to bright light
Essential for colour vision
Each come associated with one ganglion cell
What do rods and cones contain?
Photo pigments
What happens when photo pigments are struck by light?
Release energy
What happens in the primary visual cortex?
Signals from left visual field reach right visual cortex and vice versa
What’s the optic chiasm?
Part where axons cross over
What happens after the optic chiasm?
Signals then go through thalamus and then to primary visual cortex
What does it mean that the visual pathway is retinotopic?
Each level of the system is organised like the retina
What’s the summary pathway?
Eye - retina - brain
How do we perceive edges?
Edge perception = contrast perception
Why do we need to move our eyes?
Critical for high acuity and so retinal images don’t disappear
What are saccades?
Brief eye movements
What does perception of an objects colour depend on?
Mixture of wavelengths
What are the 2 principles of colour vision?
Component and opponent processing
What are component processing “thrichromatic theory”?
3 different types of cones
Perceived colour depends on the relative activity of the 3 cones
What’s opponent processing?
Neurons respond in opposite directions to complementary colours
Such as red-green and blue-yellow
What’s the colour blindness test?
Isihara colour test
Why does colour blindness happen?
Deficiency or absence of photopigments responsive to a certain wavelength
What gene is colour blindness carried on?
X chromosome
What is the process called in colour constancy?
Top down processing
What is the primary sensory cortex?
Striate cortex
What are the secondary sensory cortexes? (2)
Prestriate cortex
Inferotemporal cortex
What is the posterior parietal cortex?
The association cortex
What are the 2 major pathways/streams in visual system?
Dorsal and ventral
What’s the binding problem?
How the visual areas produce a perception of a single object
What’s one idea of the binding problem?
Sensory information converges into areas sensitive for more complex stimulus characteristics
What’s the alternative idea of the binding process?
Binding of a percept requires simultaneous activity in the brain areas
Assembly of Neurons
Touch and pain are aspects of which system?
Somatosensory system
What’s the first pathway carrying receptors to the brain?
Carries info of touch and proprioception (position of the body)
What’s the second pathway carrying receptors to the brain?
Carries info of pain and temperature
What’s the s1?
Postcentral gyrus
What’s the s2?
The secondary somatosensory cortex
Which 2 neurotransmitters are released during pain?
Mild pain : glutamate
Strong pain : glutamate and substance P
What happens in pain relief?
Body produces own opiates and endocrines
Which block release of substance P
When are endorphins released?
Pleasant and unpleasant stimuli
MOODLE
The optic nerves from the right and left eye initially meet at the _______
Optic chiasm
The blind spot in each eye is blind because _______
There are no receptors there
MOODLE
The fact that all colours on older televisions were created by combining only three different colours of light supports the _______ theory of colour vision
Trichromatic
MOODLE
the enhancement of contrast at the edge of an object is the result of _____
Lateral inhibition in the retina
MOODLE
Damage to the dorsal stream may interfere with _______
Reaching out to grasp an object
MOODLE
Colour blindness results from _____
Deficiency or absence of photopigments responsive to a certain wavelength
What is sensation?
Process of detecting the presence of a stimulus
MOODLE
Studies with placebos and studies using hypnotism suggests that much of the reduction in pain is the result of decreased activation in the _______
Somatosensory areas of the cortex
MOODLE
What processes is predicted by the gate-control theory of pain?
Pain information grows more intense as it passes each synapse on its way to the brain
