Sensory Modalities Flashcards
When can humans see colour?
Bright light (Cones)
What causes colour vision defects?
X-chromosome recombination
What do colour blind people have in terms of vision?
Dichromatic
What do most mammals lack?
M cone
What are the neural correlates and mechanism of the retina?
Small optical projection of scattered light of different wavelengths on the retina
- Signals from 2 or more photoreceptor types enable comparison of wavelength distributions in each point of the visual field
- Colour coding interneurons in P-pathway
- Colour-sensitive neutrons in V4/IT
What does the colour vision pathway consist of?
S,M and L cones in retina and bipolar cells
Colour coding P ganglion cells in retina and P-cell layers in LGN
Colour sensitive neutrons and networks in visual cortices 1, 2 and 4
What project colour to different layers in the LGN?
P- and M- ganglion cells
What are the features of P-ganglion cells?
Small rfs, slower conduction speed, high acuity, poor response to transient stimuli, colour-sensitive
What are the features of M-ganglion cells?
Large rfs, higher conduction speed, sensitive to motion, low acuity, no colour discrimination
What is sound measured by?
Sound frequency (reciprocal of wavelength
Amplitude (Loudness)
What does the ear not do?
Spatially map locations of sound
What does the ear do?
Sorts sounds by wavelengths via tonotopic mapping in the inner ear
Where are vibrations amplified?
Middle ear bones -> transmits stimulus to inner ear
What are used to stretch ion channels?
Bending of sterecilia
What is the process of stereocilia?
Bending allows opening of nonselective ion channels that allow influx of K+ and Ca2+ ions
- Hair cell is depolarised, opening voltage gated Ca2+ channels in the base of hair cell
- Neurotransmitter is released to excite afferent auditory interneurons
What is the pathway from the receptor to the primary cortex?
Superior olivary nuclei of the brainstem receives inputs from both cochlear nuclei for binaural coding of location of sound
- Further tonotopic/spatial mapping in inferior colliculi located in medial geniculate nuclei of thalamus and primary auditory cortex
What makes performance better?
Binaural stimulation (both ears listen)
What is the cocktail party effect?
Ability to drive attention towards one stimulus filtered out from the noisy environment
