Transcript Lecture 5 - TeachLine

‫ניורוביולוגיה ומדעי המח‬
‫ – מערכת הראייה‬2 ‫חלק‬
Introduction to Neurobiology
Part 2 – The Visual System
Shaul Hochstein
‫ניורוביולוגיה ומדעי המח‬
Introduction to Neurobiology
Introduction to Sensory Systems
The Visual Cortex
“From Neuron to Brain”: Chapters 20 & 21:
pages 411-433;
Signaling in the LGN & primary visual cortex
& Functional architecture of visual cortex
‫ניורוביולוגיה ומדעי המח‬
Introduction to Neurobiology
Introduction to Sensory Systems
What do we mean by “why” in science?
What is the primary goal of neuroscience?
4 principles of physiological research
Study of receptive fields is equivalent •
to study of computation; (from
input/output can deduce computation).
Study of RF linearity/nonlinearity •
essential for deriving mechanisms.
Division into neuron classes basic for •
visual system, differentiating processing
pathways, using one, the other, or a
combination of streams.
Analysis of response types may aid in •
understanding neuron role/function.
‫ניורוביולוגיה ומדעי המח‬
Introduction to Neurobiology
Introduction to Sensory Systems
To where are retinal signals transmitted?
To where are retinal signals transmitted?
and
Torsten
David Hubel
Wiesel
‫ניורוביולוגיה ומדעי המח‬
Introduction to Neurobiology
Introduction to Sensory Systems
Mapping the receptive field of visual system
neurons using small spots of light or dark.
Very effective in RGC & LGN.
Very problematic for Visual Cortex.
This is nonsense:
The responses of cortical
Simple cells depend largely,
essentially and dramatically
on intra-cortical networks.
This gives a false impression:
We do not know that Complex
cells depend on Simple cell
input and it is clear that
end-stopping exists in Simple
cells and is not a “hypercomplex” property.
The primary visual cortex maintains:
1- visual hemifield location map
2- size discrimination (small and large receptive fields)
3- color coding (in monkey; in “blobs”)
The primary visual cortex begins selectivity to:
1- orientation
2- ocular dominance and binocularity, leading to
3- stereo depth perception
4- receptive field complexity (Simple vs. Complex cells)
5- end-stopping
6- motion direction sensitivity
Visual field
magnification factor