Visual System Flashcards
1
Q
Retina
A
- Contains photoreceptors
- Image is double-inverted
- Optic disc is blind spot
2
Q
Fovea
A
- Almost exclusively cones
- Farther from fovea, more rods appear & less cones
- Where visual acuity is greatest
3
Q
Optic Disc
A
- Where blood vessels enter and leave the eye
- No photoreceptors results in blind spot
4
Q
Photoreceptor Signaling
A
- After light hits photoreceptors, G-protein coupled signaling pathway results in closing of Na+ channels
- Signals through hyperpolarization
5
Q
Cell Types in Retina
A
- Bipolar cells
- Retinal Ganglion cells
6
Q
Interneurons
A
- Amacrine & Horizontal cells
- Locally-focused
- Manage signaling
7
Q
Visual Pathway
A
- Photoreceptors
- Bipolar
- Retinal Ganglion
- Optic Nerve
- Lateral Geniculate Nucleus (Thalamus)
- Primary Visual Cortex
8
Q
On-center/Off-surround Receptive Field
A
In presence of light in center:
- Depolarization
- Metabotropic Receptor (mGluR6)
9
Q
Off-center/On-surround
A
In presence of light in center:
- Hyperpolarization
- Ionotropic Receptor (AMPA)
10
Q
Simple Cortical Cell’s Receptive Field
A
- Bar & Edge detector
- Exclusive to V1
- Sensitive to orientation, width, and location
11
Q
Complex Cortical Cell’s Receptive Field
A
- Broader & more complex edge detection and motion features
- Not exclusive to V1
- Sensitive to orientation & motion more than location
12
Q
Parvocellular
A
- Input from P cells (small ganglion cells)
- Small receptive fields
13
Q
Magnocellular
A
- Input from M cells (large ganglion cells)
- Large receptive fields
14
Q
Ventral & Dorsal Stream
A
Ventral: what?
Dorsal: where?
15
Q
Range Fractionation
A
Rods: high sensitivity
Cones: low sensitivity
16
Q
Visual v. Receptive Field
A
Visual Field: Whole area of vision without moving head or eyes
Receptive Field: Stimulus region of individual cells
17
Q
Optic Nerve
A
Made up of axons of retinal ganglion cells
18
Q
Retinotopic Mapping
A
- Topographic projection of visual field in V1 & extrastriate regions
- Most visual space devoted to foveal region
