The Journal of Neuroscience, August 9, 2006, ():
Background Synaptic Activity Is Sparse in Neocortex
J. Neurosci. Waters and Helmchen
26: 8267
Supplemental data
Files in this Data Supplement:
- supplemental material
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Supplementary figure 1. Input resistance measurements from sharp microelectrode recordings. (A and B) Examples of recordings with sharp electrodes showing the brief pulse protocol and the constant current injection protocol. (C) Mean (± SEM) input resistances measured using brief current pulses. (D) Mean (± SEM) membrane time constants measured from the brief pulse protocol. (E) Mean (± SEM) input resistances measured using constant current injection (10th and 90th percentiles). Mean input resistances for the Down state, Discards, and Up state groups were 22.5 ± 3.5 MΩ, 24.5 ± 6.8 MΩ and 23.6 ± 4.4 MΩ, respectively (n = 3 neurons; no significant difference between Up and Down states, P < 0.5).
- supplemental material
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Supplementary figure 2. Simulation of high-conductance Up states without anomalous rectification
(A) To compare our low-conductance scenario with the prevailing view of Up states as high-conductance states, we also simulated high-conductance Up states using point-conductance model with a passive membrane (without anomalous recitifcation) and Poisson-distributed excitatory and inhibitory synaptic inputs. (B) Up states were generated by 500 ms step increases in the mean rates of synaptic input. The model was constrained to produce an 80 % drop in input resistance, which required a high total synaptic conductance change (138 nS; excitation 34 nS, mean rate 15 kHz; inhibition 104 nS, mean rate 16 kHz). (C) A reversed / ratio of about 3:1 was necessary to maintain the mean depolarization (ΔV) within the experimental range. Grey areas represent mean ± standard deviation of experimental results.
