Transcript Lecture Exam #3 Review Slides

The Nose
Malleus
Tympanic Membrane
Incus
Stapes
• The middle ear amplifies signal by
increasing the pressure on the oval window
• Inner ear muscles provide adjustable
intensity control (dampen sounds)
Basal
Thick
Stiff
High frequency
stapes
Apical
Thin
Floppy
Low frequency
Basilar membrane
We Love Fourier!
One Version of the Auditory Pathway
A1
A1
MGN
MGN
IC
IC
superior
olive
superior
olive
cochlear
nucleus
cochlear
nucleus
Different cells in the retina
Back of eye
6. Pigment cells
1. Receptor Cells
(Graded potential)
(input)
2. Bipolar Cells
(Graded potential)
3. Ganglion Cells
(action potential)
(Output)
4. Horozontal Cells
(Graded potential)
5. Amacrine Cells
(Graded/action potential)
Front of eye
Distribution of Rods and Cones
Rods
Cones
High light sensitivity
Night vision
Low light sensitivity
Day vision
Achromatic
Chromatic
Low acuity—not in the
fovea
High acuity—in the
fovea
Slow response
Fast response
General organization of the visual pathway
Receptive field
• Definition: the area of the retina (or visual field) in which light
signals evoke responses
• It’s a property of the cell, not a cell or a part of the cell
• It depends largely on the synaptic inputs to the cell and to some
degree the biophysical property of the cell itself
receptive field
LGN cells
cortical
simple cell
LGN layers
• Parvocellular
layers: 3-6
• Magnocellular
layers: 1,2
• Contralateral eye:
1,4,6
• Ipsilateral eye:
2,3,5
• But all LGN layers
represent
contralateral visual
field!
Yang Dan is Way too Cool
Circuitry -- inputs, outputs and layering
1
Input
2/3
LGN  layer 4, layer 6
4A
Layer 4  layer 2/3 
layer 5  layer 6
4B
4
4C
Output
4C
Layer 2/3, Layer 4B 
other visual cortical areas
5
Layer 5  superior
colliculus
6
Layer 6  LGN
M P
(LGN)
fixation point
left visual field
nasal
half
right visual field
left
right
nasal
half
temporal half
temporal half
nasal retina  contra LGN
temporal retina  ipsi LGN
optic
chiasm
LGN
V1
V1
L visual field  R LGN  R V1
R visual field  L LGN  L V1
Transneuronal transport technique to look at OD columns
eye
LGN
V1
layer 4
L
radioactive
R
amino acid
6
5
4
3
2
1
C
I
C
I
I
C
L
R
2
L
R
L
V1 cells have orientation selectivity
receptive field
orientation response
LGN cells
1
2/3
4
5
6
cortical
simple cell
Hypercolumn
cortical surface
layers
180o, ~1mm
• One L/R cycle + one 180o rotation = one hypercolumn.