Lecture 21: Finishing Vision and Hearing 1 Flashcards
What is the retina responsible for?
for converting light energy into patterned changes of membrane potential
Information from photoreceptors and interneurons is combined so that what?
So that the output from ________ cells depends critically on the _______ and _________ pattern of light _________ on the _______
the output from ganglion cells depend critically on the spatial and temporal pattern of light stimulation on the retina.
Where are receptive fields large and small?
in the fovea very small, in the periphery of the retina much bigger
Where are there no photoreceptors?
in the optic disc
Where are objects in and out of their visual context analysed?
in the visual cortex
For analysis of form, cells in the visual cortex are responding to what?
edges and corners
For analysis of movement, there are cells in the visual cortex responding to what?
direction of movement and direction of movement in relation to the background
For analysis of colour, there are cells in the visual cortex responding to what?
wavelengths coming from an object in relation to wavelengths coming from objects nearby, and an average of wavelengths from objects in other parts of the field of view
Information processed in the visual cortex is used for what?
To discriminate between ______ and _______, to tell us ______ objects are, ______ they are, and where they are ________
to discriminate between objects and background, to tell us what objects are, where they are, and where they are moving
What are the two halves of each retina called and where are these?
the nasal retina (the half of each retina that is closest to the nose) and the temporal retina (the half of each retina that is closest to the temples)
Objects from the left visual space are processed where?
in the right brain, and vice versa
Information is sent from the eye to ______ ________ in the brain in such as way as to preserve what?
_______ relationships between ______ stimuli
visual centres
spatial relationships between visual stimuli
Describe the pathway of information being sent from the eye to the brain due to something being detected in the left visual space of the left eye?
If is it detected in the left visual space of the left eye, it will be detected on right of the retina in the left eye. The information will be sent down the optic nerve behind the left eye into the brain and cross over onto the right side of the brain at the optic chiasm. It it then projected down the optic tract of the right side of the brain until it reaches the Lateral geniculate nucleus. It then travels to the right side of the occipital lobe to the visual cortex
Describe the pathway of information being sent from the eye to the brain due to something being detected in the left visual space of the right eye?
If is it detected in the left visual space of the right eye, it will be detected on right of the retina in the right eye. The information will be sent down the optic nerve behind the right eye into the brain but remain on the right hand side of the brain after travelling to the optic chiasm. It it then projected down the optic tract of the right side of the brain until it reaches the lateral geniculate nucleus. It then travels to the right side of the occipital lobe to the visual cortex
Describe the pathway of information being sent from the eye to the brain due to something being detected in the right visual space of the left eye?
If is it detected in the right visual space of the left eye, it will be detected on left of the retina in the left eye. The information will be sent down the optic nerve behind the left eye into the brain but stay on the left side of the brain at the optic chiasm. It it then projected down the optic tract of the left side of the brain until it reaches the Lateral geniculate nucleus. It then travels to the left side of the occipital lobe to the visual cortex
Describe the pathway of information being sent from the eye to the brain due to something being detected in the right visual space of the right eye?
If is it detected in the right visual space of the right eye, it will be detected on left of the retina in the right eye. The information will be sent down the optic nerve behind the right eye into the brain and cross over onto the right side of the brain at the optic chiasm. It it then projected down the optic tract of the left side of the brain until it reaches the Lateral geniculate nucleus. It then travels to the left side of the occipital lobe to the visual cortex
Does information from the nasal retina cross over or stay on the same side? What is the name for this?
crosses over to the other side
contralateral
Does information from the temporal retina cross over or stay on the same side? What is the name for this?
stays on the same side
ipsilateral
Where do axons leave the retina?
at the optic disc
Where is the blind spot on the eye? Why is this?
at the optic disk because there are no photoreceptors at this point
Axons from ganglion cells in the nasal retina cross at the optic chiasm to project ___________
contralaterally
Axons from ganglion cells in the temporal retina do not cross at the optic chiasm to project _________
ipsilaterally
Ganglion cell axons project to what four main subcortical visual areas?
- superior colliculus
- lateral geniculate nucleus
- pretectum
- suprachiasmatic nucleus
What is the role of the superior colliculus?
it is concerned with eye movements and orientation to visual stimuli
What is the role of the lateral geniculate nucleus?
it is concerned with the sensation of vision
What is the role the protectum?
control of the pupils contsricting
What is the role of the suprachiasmatic nucleus?
day and night vision (control of diurnal rhythms)
Cells of the LGN send axons where?
into the visual cortex
After processing in the visual cortex, information can be sent to what three places?
temporal lobe and parietal lobe
and frontal cortex
What happens to the visual information in the temporal lobe?
it is used for identification of objects in the visual space (the “what”)
What happens to the visual information in the parietal lobe?
it is used for processing of information regarding the location of objects in space (the “where”)
What is information that passes to the frontal cortex used for?
to help direct actions
What is sound?
different pressure waves in the atmosphere
What are zones of compression?
areas of high pressure
What are zones of rarefaction?
areas of low pressure
areas of low pressure are called zones of what?
rarefaction
Areas of high pressure are called zones of what?
compression
What is a sound wave?
alternating zones of high and low and high pressure`
What is the frequency of a sound wave?
the number of waves per second
What does the frequency alter? What is it measured in?
the pitch
Hz
What is the amplitude of a sound wave?
the height of the sound wave
What does the amplitude change? What is it measured in?
the loudness
decibels
What two things does the threshold of hearing depend on?
the stimulus frequency and the amplitude
What is the normal hearing threshold? Why is this?
between 50Hz and 10000Hz and 0 and above decibels because this is the range of a normal human voice
What is the amplitude of normal speech?
60dB
