Revised. tedious, and it disrupts the circulation of an essentially simple argument. Therefore, I leave it in the Methods section available for those who need to dig deeper. I also made a few minor word changes in the Abstract and Introduction, and improved the colouring in Physique 10 for better visibility. Peer Review Summary recordings ( 2, Physique 2C). Physique 2. Open in a separate window Responses to pure tones in main auditory cortex from awake monkeys 40 and firing rates from main auditory cortex in rats 2. A: Distribution of spike rates to a 50ms firmness ( = 119, reddish) 100ms firmness ( = 115, blue), or 200ms firmness ( = 23, green) in main auditory cortex in monkeys 40. B: Histogram for spike rate distribution for the 100ms firmness response ( = 115) fitted by an exponential (reddish) or lognormal (blue) distribution 40. C: Spontaneous spike rate distribution from main auditory BGJ398 kinase activity assay cortex in unanesthetized rats 2 fitted by an exponential (reddish) or lognormal (blue) distribution. Note that the spontaneous firing rates Rabbit polyclonal to PTEN are much lower and narrower distributed than evoked spikes in response to stimuli at short time scales ( B), but that they still follow a lognormal distribution. For midbrain nuclei neurons (IC), we re-analyzed spike rates in response to tones (for 200ms after stimulus onset) under variations of binaural correlation 45. The frequency rating of neurons by mean spike rate, standard deviation, min-max values, CV and FF are shown in ( Physique 3ACC). CV and FF are similar to the cortical data. Data from GABAergic cerebellar Purkinje cells offer some difficulty for this analysis since they have regular single spikes at high frequencies, and in addition, calcium-based complex spikes 43. Complex spike rates however are low ( 1 recordings in anesthetized rats 43 ( Physique 4A) and data from spontaneous spiking (in the absence of synaptic activation) under conditions ( 41, 42, Physique 4B and C). Physique 3. Open in a separate windows Neuronal response to binaural activation for substandard colliculus of the guinea pig 45 ( = 30), data collected over 100 ms, 200C500 trials.The data are shown for each neuron, with neurons sorted by imply spike count. A: Mean spike rates (blue), standard deviation (reddish), and minimum/maximum absolute values (green). B: Mean spike rates histogram shows a lognormal distribution. C: Distributions of standard deviation (green), CV (blue) and FF (reddish). Again, the dispersion is fairly constant. Figure 4. Open in a separate window Spike rates for cerebellar Purkinje cells from rats 41C 44. A: Data for single spikes for Purkinje cells recorded from anesthetized rats (spontaneous = 346). B: Data for spike frequencies of isolated cell body of mouse Purkinje cells = 34). C: Spontaneous spike rates for Purkinje cells in slices ( = 106) 42. D: Spike counts per neuron from 41 ( = 34), together with variability data from 44 ( = 2). In order to show values for standard deviation and variance, data for two Purkinje cells from a behavioral experiment, 44, i.e. single spike rates during arm movements from monkeys, have been added to the rating of spontaneously firing neurons by imply spike rate from 41 ( Physique 4D). The logarithmic (heavy-tailed) distribution of spike rates is obvious under all conditions. The distribution of spike rates for neurons spiking in the absence of synaptic input shows that there are differences in the intrinsic excitability of neurons. To further explore this we looked at three additional datasets, which statement the action potential firing of a cell due to injected current, such as by a constant pulse. This can be defined as the neuronal gain parameter (spike rate divided by current, [Hz/nA]). 1. medium striatal neurons in slices from rat dorsal striatum and nucleus accumbens shell (NAcb shell) 3, cf. 1, Physique 5. 2. cortical neurons in cat area 17 = 28, solid lines) and nucleus accumbens shell ( = 24, dashed lines). B: Gain (Hz/nA) for BGJ398 kinase activity assay neurons in dorsal striatum ( = 28). C: Gain (Hz/nA) for neurons in BGJ398 kinase activity assay NAcb shell ( = 24). Physique.