Midterm 2 Review Topics

MCB 160 Fall 2006

Midterm 2 Review Topics

1. Audition
2. Anatomy of the inner ear/hair cells

1. Shape of basilar membrane: frequency tuning
2. Function of inner hair cells vs. outer hair cells
3. Hair bundle: group of cilia connected by tip links
4. Signal transduction

1. Movement of cilia  K+ influx from endolymphdepolarization
2. VGCCs and Ca++ activated K+ channels in cell body: increased tuning specificity
3. Tonotopic map in cochlear nucleus

1. Olfaction

1. Anatomy of the olfactory epithelium/olfactory bulb
2. Coding of scents
3. Each cell expresses one receptor type
4. One odor activates multiple receptors
5. All cells expressing one receptor send their axons to a common glomeruli
6. Signal transduction

1. Odorant receptors = GPCRs
2. Binding of odorant increased [cAMP], opening of cAMP gated ion channels, depolarization

1. Vision: Signal Transduction in the Retina
2. Anatomy of the eye/retina
3. Rods vs. cones
4. Dark current
5. PRs are depolarized in the dark, hyperpolarize in response to light (graded response)
6. Current flows into outer segment, out of inner segment
7. Signal transduction pathway: lightclosing of cGMP gated channels, hyperpolarization
8. Turning signal off: rhodopsin kinase (fast), dissociation of all-trans retinal (slow)
9. Adaptation/Desensitization: 3 calcium-sensitive mechanisms

1. Vision: Processing in the Retina
2. Receptive fields
3. Convergent and divergent processing
4. Center/surround organization of on and off bipolar cells/RGCs
5. Lateral inhibition by horizontal cells

1. Vision: Processing in the LGN/Primary Cortex
2. Separation of info from right/left visual fields at optic chiasm
3. Segregation of inputs into different layers of the LGN (magno/parvocellular, ipsi/contralateral)
4. Receptive fields of LGN cells: similar to RGCs
5. Neurons from LGN project to layer 4 of primary cortex
6. Simple/complex cell receptive fields in cortex
7. Ocular dominance columns, ‘pinwheel’ of orientation selectivity

1. Development: Neurulation
2. Blastula/gastrula anatomy
3. Formation of neural tube, neural crest
4. Dorsal lip (organizer) induces neurulation
5. TGFβ/BMP signaling: promotes epidermal fate
6. Noggin: binds BMP, allows cells to adapt default neural state
7. Threshold: smooth signal gradient  distinct cell fates

1. Development: Polarity
2. Dorsal/ventral spinal cord polarity
3. Notochord secretes sonic hedgehog: induces ventral cell fates, inhibits dorsal cell fates
4. BMP induces dorsal cell fates and inhibits ventral cell fates
5. Anterior/posterior polarity
6. Anterior/posterior divisions:
7. Prosencephalon, mesencephalon, rhombencephalon
8. Telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
9. Homeotic genes (Drosophila), Hox genes (vertebrates)
10. Encode transcription factors
11. position on chromosome correlates to expression
12. combo of Hox genes expressed determines cell fate

1. Development: Cortex
2. 3 zones of immature cortex: cortical plate, intermediate zone, ventricular zone
3. Techniques: birthdating and lineage tracing
4. Layers established sequentially: inside out
5. Evidence supporting instructional model of establishing layer-specific fates

1. Development: Cell Specification and Neurotrophins
2. Fate determination of neural crest derivative cells: fate determined by target-derived factors
3. Apoptosis vs. necrotic death
4. Neurotrophic factors
5. Chick limb experiment
6. Neurotrophin family: BDNF, NGF, NT3, NT4/5
7. Neurotrophin receptors: trk A, B, C