week 4 - visual pathways Flashcards
electronic map on V1
primary visual cortex
retinotopic map
an electron map of the retina on the cortex
cortical magnification
a small area of the fovea is represented by a large area on the visual cortex
What techniques are used to research the retinotopic map and cortical magnification
brain imaging techniques such as PET and fMRI
What part of the eye contains more cortex/neurons?
fovea
Why do we have overrepresentation of the fovea on our visual cortex?
more detail and acuity is needed for more information
Do we have cortical over-representaiton in our other senses?
in the somatosensory system, we have certain body parts that receive more information such as hands and face
Why is the visual cortex also known as the striate cortex?
it is organized in columns
What type of columns does the visual cortex contain?
- location columns
- orientation columns
location columns
receptive fields at the same location on the retina are within the same column
orientation columns
- neurons within columns fire maximally to the same orientation of stimuli
- adjacent columns change preference in an orderly fashion
Describe Hubel’s and Weisel’s research regarding the primary visual cortex and columns.
- used recording electrodes to find neurons in the visual cortex
- pierced down from the surface of the cortex to showcase the receptor fields of each of the neurons they encountered
What did Hubel and Weisel conclude with their research regarding the primary visual cortex and location columns?
Our visual cortex is organized in location columns. The receptive fields of neurons are stacked on top of each other, meaning they were all in charge of the same area.
What did Hubel and Weisel discover after piercing through the surface in a vertical fashion?
Found that they were in a horizontal orientation
What occurred when Hubel and Weisel moved the electrode obliquely through the location column?
all of the potential light bars or orientation are represented by different simple cortical neurons within that single location column
hyper column
all the orientation columns within the location columns
What is the purpose of a hyper column?
- receives all possible information that could potentially light up a specific location of retina
- well-suited for processing information from a small area of your visual field
ocular dominance columns
neurons in the cortex respond preferentially to one eye
tiling
columns working together to cover the entire visual field
How do feature detectors respond to a scene?
tiling
dorsal pathways
visual information is sent to parietal lobe
ventral pathway
visual information is sent to temporal lobe
What are the differences in visual information processing between the parietal and temporal lobe?
- temporal lobe processes what the information is
- parietal lob processes where/how the information is
Describe Ungerleider and Mishkin experiment
- animal is shown object and presented with two choice task
- animal given reward for detecting target object
- specific lobe is removed and animal is unable to recognize correct target object
After the temporal lobe was removed, what ability did the animal lose?
was unable to recognize object discirmination
After the parietal lobe was removed, what ability did the animal lose?
was not able to locate where the food was hidden after learning it in repeated trials
What pathway is also called…
ventral pathway
Where pathway is also called…
dorsal pathway
What are similarities between the dorsal and ventral pathways?
- originate in retina and continue through two types of ganglion cells in LGN
- have some interconnection
- receive feedback from higher brain areas
If someone damaged their temporal lobe, would they have more trouble naming and object or determining its location?
naming the object
If someone damaged their parietal lobe, would they have more trouble naming and object or determining its location?
determining the object’s location
Explain the streams for information about what and how for the patient whose ventral pathway was damaged by gas leak.
- not able to match orientation of card with slot
- able to match orientation if she was placing card in a slot
- evidence shows double dissociation between ventral and dorsal pathways
module
a brain structure that processes information about a specific stimuli
What does damage to the temporal lobe result in?
prospagnosia aka “face blindness”
fusiform face area (FFA)
responds best to faces
parahippocampul place area (PPA)
responds best to spatial layout
extrasite body area (EBA)
responds best to pictures of full bodies and body parts
H.M. and hippocampus
- removal of hippocampus decreased seizures but eliminated ability to form new memories
- suggests that hippocampus is possibly in charge of recognizing/remembering objects
Greeble experiment
- training participants to Greeble results in an increase of areas of FFA response
- responds best to whatever someone is an expert in
