Lecture 6 Flashcards
How is V1 organized?
an ‘electronic map’ of the retina
What does retinotropic mean?
two points that are close together on an object (and thus are also
close together on the retinal image formed by looking at the object) are also
represented in parts of the cortex that are close together
Describe cortical magnification
a small area
of the fovea is represented by a large
area on the visual cortex
• This is one of several mechanisms
that contribute to high-acuity vision
Describe IT neurons
e.g. neurons in the inferotemporal (IT) cortex respond to more complex stimuli than
neurons in V1
What is the FFA?
The fusiform face area (FFA) has neurons which tend to respond best to
faces (though the ‘specificity’ of this area is hotly contested!)
What is sensory coding?
refers to the way perceived objects are represented through
neural firing
What are the 3 types of sensory coding?
- Specificity Coding
- Population Coding
- Sparse Coding
Describe specificity coding
specific (individual)
neurons respond to specific stimuli
What is the grandmother cell hypothesis?
Describe Quiroga study
a unique research opportunity to
measure the response of individual
neurons in humans undergoing surgery
for epilepsy, finding neurons that
seemed to respond to the presentation
of specific faces (e.g. Steve Carell)
What is one problem with specificity coding?
• Too many different stimuli to assign specific neurons?
What is population coding?
pattern of
firing across many neurons codes
specific objects
Describe sparse coding
only a relatively
small number of neurons are
necessary to code for each
concept/identify, etc.
Describe the MTL
Medial temporal lobe (MTL) structures are extremely important for memory
(e.g. parahippocampal cortex, entorhinal cortex, hippocampus)
• Signals coming from IT cortex
project to MTL
Describe Quiroga 2005, 2008 study
Quiroga et al. (2005, 2008) reported results for a patient undergoing surgery for
epilepsy had the activity of individual neurons in their temporal lobe recorded
• Neurons were found that responded to images of one specific actor but not
others, which could potentially represent an example of specificity coding
(though there are other possibilities…)
