The Importance Of Short-Term Plasticity At The ORN PN Synapses

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Short-term plasticity at the ORN  PN synapse could result in PN responses that are strongest during the rising phase of the ORN response since the ORN  PN synapses display short-term depression that causes ORN spikes that arrive later to produce smaller postsynaptic potentials than the ones produced by earlier spikes. In depressing synapses, successive action potentials result in smaller and smaller postsynaptic responses. The reduction in postsynaptic responses could be due to smaller amount of neurotransmitter release by the presynaptic neuron. Depressing synapses are characterized by high starting release probability. Thus, there are large amounts of neurotransmitter release at beginning of stimulus train. However, this large amount of …show more content…
Thus, is the stimulus distribution changes, the efficiency of a coding scheme would change. Bhandawat and colleagues’ conclusions depend on their stimulus set being representative of natural stimuli because if their stimulus set was not representative of natural stimuli, then the ORNs and PNs would elicit different responses and the efficiency of a coding scheme would be different from their natural responses and effiency. The ways in which natural odor stimuli might differ from the stimuli used by Bhandawat et al. are that there could be more natural odor stimuli that they did not account for since they did not sample all antennal lobe glomeruli and that the odors they used were not taken from the Drosophila’s natural environment. Thus, despite being chemically diverse and relatively large, the stimuli they used might not be odors a wild fly wound come …show more content…
Since the LNs affect the probability of neurotransmitter release, if lateral inputs were blocked, then more neurotransmitter release might occur, so the postsynaptic responses would not be as weak, and the efficiency of transforming ORN action potentials to neurotransmitter release could increase. As a result, the relationship between PN and ORN responses might not be as nonlinear as the one in flies with intact lateral connections. In addition, PN responses during the rising phase of an ORN response might not be as strong, and the PNs might be less broadly tuned and more selective to odors. Lateral inputs would have an odor tuning that reflects the odor preferences of ORNs that are presynaptic to other glomeruli, so blocking these inputs would affect the tuning. Furthermore, the rank order of PN and ORN odor preferences might change. Lateral interglomerular connections can cause these differences in odor rank order, so lateral connections can contribute to glomerular transformation functions. Thus, blocking the lateral connection might change these ORN-to-PN

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