Describe serial processing?
it's when you have the 1st order neuorn activating the 2nd, which activate sthe 3rd, etc.
it's basically the basis of the labelled line mechanism for transmitting information
Describe parallel processing?
It's where the signal diverges and you get input from one primary neuron onto multiple secondary neurons
thus, the signal travels thorugh multiple strings of neurons instead of just one as in series processing
What is convergence?
it's where input form 2 cells synapses on one post-synaptic cell
note this can occur across modalities
What are the facotors affecting an individua's awareness of a sensory input?
1. the set of receptors they have
2. the functionality of the receptors they have
3. the receptor mechanism itself
4. selective attention
5. emotions and experiences
Through what mechanism are ganglion cells able to detect contract?
through lateral inhibition
what cells provide the lateral inhibition for the ganglion cells?
the amacrine cells
How do the receptive fields of photoreceptors differ from the receptive fields of the gannglion cells?
photoreceptors just have round recetive fields
ganglion cells have bigger receptive fields and they have a surround and a center (like a doughnut)
How will "on" GCs differ from "off" GCs?
on GCs will depolarize in response to bright light (of their preferred color) hitting their center and will hyperpolarize in response to light hitting their surround
OFF GCs will depolarize in response to light hitting their surround and will hyperpolarize in response to light hitting their center
What will the bipolar cells do to the signal for an ON gangion cell? How about for an OFF ganglion cell?
remember that photoreceptors hyperpolarize
so...for an ON ganglion cell, the bipolar cell will flip the signal to cause depolarizaiton in the center
for an OFF ganglion cell, the bipolar cell will just send the hyperpolarizaiton as it, causing hyperpolarization in the center
How can an amacrine lead to depolarization in the surround of an OFF ganglion cell?
it's thoruhg lateral inhibition
when activated, the amacrine cells will inhibit the inhibition of hyperpolarization in the surround, causing a depolarization
In the visual cortex you basically get a reconstruction of the visual image. What are the 3 dimensions of this?
1. first dimension of organization is where you select fFEATURES of the visual field
- occurs with alternating eye representation lending itself to ocular dominance
2. in the second dimension you have orientaiton columns, which give you line orientation AND motion
3. Int he third dimensions you have the blob reigons that give you color
What dimension of the visual cortex organization gives you depth perception?
the ocular dominance columnar organization
How do the ganglion cell responses ultimately lead to motion perception?
1. ganglion cells converge into simple cell responses, which respond to only a specific orientation of a line
2. the simple cell responses combine into complex cell responses, which respond to motion of the line via each simple cell responding to a specific orientation of a line
Within the primary visual cortex, what areas are overrepresented?
the fovea is overrepresented relative to the periphery, which makes sense because that's where the most photoreceptors are
what's the fancy word for depth perception?
Since the fovea is overrepresented, is has ____ convergence/
What is strabismus?
It's an EOM muscle imbalance that results in a misalignment of the axis of the two eyes
What will strabismus result in if it occurs before 6 onths of age? After 6 months of age?
before 6 months of age, the cortex basically suppresses the image of the weaker eye, causing a permanent decrease in visual acuity (amblyopia)
after 6 months, the cortex can't suppress it, so you get a diplopia because the image falls on different parts of the two retinas
In terms of wavelength, what color is short and which is long?
blue has short wabelenths, green is medium, red is long wavelengths
In color perception, what gives you luminescence?
activity of both long and medium wavelengths - red and green cones plus rods
In color perception, what radoi gives you red/green contrast?
the ratio between long and medium wavelengtsh
In color perception, what gives you blue/yellow differences?
short wavelength - (long and medium wavelength)
Do we all see color the same?
probably not - everyone has unique distributions of photorecepors on the retina
what we know as perception of color is actually a learned process involving figuring out what "red" is based on our own photoreceptor conglomerate
Visual cortex output gets segregated into what two pathways?
ventral stream - to the inferior temporal cortex - the "what" stream
dorsal stream - to the posterior parietal - the "where" stream
In terms of vision, what info does the ventral stream provide?
form - object identification
For vision, what info is provided by the dorsal stream?
motion and depth perception
What will a lesion in the ventral stream cause? dorsal stream?
ventral = achromatopsia and agnosia
dorsal stream = ideomotor apraxia - can't execute movements that depend on sight