l10 Flashcards
how many ORNs are there
10-15 million
10,000 types
distribution of ORN across nasal concha
distinct 4 zones of ORN types
how many odorants activate 1 ORN
one ORN can be activated by multiple odorants
- see response to many different odors
how many ORNS can 1 odorant activate
1 odorant can activate multiple types of ORNS
- see repsonse in many neurons
combanitorial coding
1 receptor can be activated by multiple odorants and 1 odorant can activate a range of receptors
- specific odors are coded by combination of ORNS
ORNs
non myelinated
coupled to cascade that opens CNG channels allowing ions to flow and generate receptor potentials
- activate Na channels
cribiform plate
where ORNs meet brain
ORN projections to Olfactory bulb
mitral cells and tufted cells are projection neurons which send axons to olfactory cortex
what is the challenge of ORNs
they turn over throughout the month- stem cells must find thier ways back to correct glomeruli
- must be some guidance or code that allows axons to find way home
organization of olfactory bulb
axons of neurons make synapses in glomerular layer
- glomeruli
0 mitral and tufted cells project to glomerulus and PG cells
- secondary dendrites in EPL layer (periglomerular and external tufted)
ganule cells project onto mitral cells
intrinsic imaging
can see multiple areas active from a number of different odorants
sniff cycle
measure activity from ORN- present odors on nose while measuring the pressure in nasal cavity
can tell exactly when odor came in
- spike in activity when odor is present and align with sniff cycle
- mitral cell activity is timed with sniff cycle
channelrhodopsin
depolarize ORNs in response to light
- light shines and channel depolarizes and fires AP
- bypass need for odorant and gives temporal precision
go./no go task
train mice to lick in response to odorant and not like when no odorant
4 target sites of Olfactory bulb
- olfactory tubercle
- pyriform cortex
- emygdala
- entorhinal cortex
- bypasses thalamus
