Analysis of temporal discharge characteristics of dorsal cochlear nucleus neurons of unanesthetized decerebrate cats

1992 ◽  
Vol 67 (5) ◽  
pp. 1247-1263 ◽  
Author(s):  
K. Parham ◽  
D. O. Kim
Keyword(s):  
Standard Deviation ◽  
Cochlear Nucleus ◽  
Time Window ◽  
Tone Burst ◽  
Dorsal Cochlear Nucleus ◽  
Interspike Intervals ◽  
Discharge Characteristics ◽  
Present Sample ◽  
The Mean ◽  
Decerebrate Cats

1. We examined the mean and standard deviation (SD) of interspike intervals (ISI) and the coefficient of variation (CV, the ratio of SD of ISI to mean ISI) of ISIs versus time to study discharge regularity of units in the dorsal cochlear nucleus (DCN) of decerebrate unanesthetized cats. The units were characterized by the use of both poststimulus time histograms (PSTH) and excitatory-inhibitory area (EI-area) schemes. We present results of a systematic examination of all of 87 DCN pause-build units recorded in this study. In addition, we present examples of chopper subtypes of the DCN. 2. A major finding of this study is that a majority of the pause-build units in the present sample exhibited regular discharges in response to short (50 ms) tone bursts at characteristic frequency (CF), as revealed by CVs less than 0.5. A predominant portion of pause-build units (80% of 44 units with sufficient number of spikes for CV analysis) exhibited mean CVs less than 0.5 in the 20- to 39.9-ms time window in response to 50-ms tone burst at CF at 60 dB SPL re 20 microPa; 39% of the 44 units exhibited highly regular discharges (mean CV less than 0.35). During the onset (2-14.9 ms) time window, 77% (of 53 units with sufficient number of spikes for CV analysis) of the units had mean CVs less than 0.5, and 55% were less than 0.35. 3. In our sample of 87 DCN pause-build units, 59% had spontaneous rates (SR) greater than 15 spikes/s. The pause-build units of the present sample were distributed across four different EI-area types: III (51%), I/III (25%), II (15%), or IV (9%). In the 20- to 39.9-ms time window, the pause-build units with mean CVs less than 0.35 were exclusively of types III and I/III. All of the above EI-area types were represented in the lowest CV group for the 2- to 14.9-ms window. 4. The mean ISIs of DCN pause-build units typically showed a decrease during the first 20-25 ms of the response to 50-ms CF tone bursts, and stable mean ISIs in the latter half, when off-discharges were absent. In the presence of off-discharges, the mean ISIs decreased further in the last 5-10 ms of the response.(ABSTRACT TRUNCATED AT 400 WORDS)

Regularity and latency of units in ventral cochlear nucleus: implications for unit classification and generation of response properties

1988 ◽  
Vol 60 (1) ◽  
pp. 1-29 ◽  
Author(s):  
E. D. Young ◽  
J. M. Robert ◽  
W. P. Shofner
Keyword(s):  
Standard Deviation ◽  
Cochlear Nucleus ◽  
Interspike Interval ◽  
Rate Adaptation ◽  
Stellate Cells ◽  
Instantaneous Rate ◽  
Ventral Cochlear Nucleus ◽  
Bushy Cell ◽  
Low Pass ◽  
The Mean

1. The responses of neurons in the ventral cochlear nucleus (VCN) of decerebrate cats are described with regard to their regularity of discharge and latency. Regularity is measured by estimating the mean and standard deviation of interspike intervals as a function of time during responses to short tone bursts (25 ms). This method extends the usual interspike-interval analysis based on interval histograms by allowing the study of temporal changes in regularity during transient responses. The coefficient of variation (CV), equal to the ratio of standard deviation to mean interspike interval, is used as a measure of irregularity. Latency is measured as the mean and standard deviation of the latency of the first spike in response to short tone bursts, with 1.6-ms rise times. 2. The regularity and latency properties of the usual PST histogram response types are shown. Five major PST response type classes are used: chopper, primary-like, onset, onset-C, and unusual. The presence of a prepotential in a unit's action potentials is also noted; a prepotential implies that the unit is recorded from a bushy cell. 3. Units with chopper PST histograms give the most regular discharge. Three varieties of choppers are found. Chop-S units (regular choppers) have CVs less than 0.35 that are approximately constant during the response; chop-S units show no adaptation of instantaneous rate, as measured by the inverse of the mean interspike interval. Chop-T units have CVs greater than 0.35, show an increase in irregularity during the response and show substantial rate adaptation. Chop-U units have CVs greater than 0.35, show a decrease in irregularity during the response, and show a variety of rate adaptation behaviors, including negative adaptation (an increase in rate during a short-tone response). Irregular choppers (chop-T and chop-U units) rarely have CVs greater than 0.5. Choppers have the longest latencies of VCN units; all three groups have mean latencies at least 1 ms longer than the shortest auditory nerve (AN) fiber mean latencies. 4. Chopper units are recorded from stellate cells in VCN (35, 42). Our results for chopper units suggest a model for stellate cells in which a regularly firing action potential generator is driven by the summation of the AN inputs to the cell, where the summation is low-pass filtered by the membrane capacitance of the cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Spontaneous and sound-evoked discharge characteristics of complex-spiking neurons in the dorsal cochlear nucleus of the unanesthetized decerebrate cat

1995 ◽  
Vol 73 (2) ◽  
pp. 550-561 ◽  
Author(s):  
K. Parham ◽  
D. O. Kim
Keyword(s):  
Cochlear Nucleus ◽  
Pure Tone ◽  
Broadband Noise ◽  
Dorsal Cochlear Nucleus ◽  
Projection Neurons ◽  
Response Latencies ◽  
Discharge Characteristics ◽  
Decerebrate Cat ◽  
Complex Spikes ◽  
Cartwheel Cells

1. We examined the spontaneous and sound-evoked discharge characteristics of 20 complex-spiking units recorded in the dorsal cochlear nucleus (DCN) of 15 unanesthetized, decerebrate cats. 2. The extracellularly recorded complex spikes consisted of bursts of two to five action potentials whose size gradually decreased during the burst. Complex spikes were observed both in the spontaneous and sound-evoked activity of the units in our sample. 3. The spontaneous rates (SRs) of DCN complex-spiking units ranged from 0 to 30 spikes/s. Spontaneous activity consisted of complex and simple (i.e., the common single neuronal action potential) spikes. Comparison of the SR distributions of the DCN complex-spiking units with that of a total sample of 194 DCN units (from 9 cats) suggests that the complex-spiking units tended to be in the lower half of the DCN SR distribution. 4. Sound-evoked discharges could consist of both complex and simple spikes. On the basis of their sound-driven responses, we divided the DCN complex-spiking units into two groups. The majority (15 of 20, 75%) were weakly driven by pure tones and inhibited by broadband noise. They tended to have broad response areas. Their response latencies to pure tone and noise stimuli were relatively long (10-20 ms). The recording depths of these units tended to be superficial (i.e., 10 of 15 units were located within 400 microns of the dorsal surface of the DCN). A minority (5 of 20, 25%) of the complex-spiking units were strongly driven by pure tone and broadband noise stimuli. These units had more clearly defined excitatory regions of response areas than the weakly driven units. Their response latencies to pure tone and noise stimuli were short (< 10 ms). The recording depths of these units tended to be deeper (i.e., 4 of 5 units were located at 400-700 microns) than those of the weakly driven units. 5. Intracellular recording and labeling studies of in vitro DCN slice preparations have correlated complex spikes with the superficially located cartwheel cells. Given the complex spikes of the units, many of which were located superficially, we suggest that our sample, particularly the weakly driven group of neurons, corresponds to the cartwheel cells. 6. Cartwheel cells are putative inhibitory interneurons whose axons primarily contact on the main projection neurons of DCN, the fusiform cells. The present finding of sound-evoked discharges by the superficially located complex-spiking units suggests that cartwheel cells should play a role in modifying the sound-evoked responses of the fusiform cells.

Firing Variability Is Higher than Deduced from the Empirical Coefficient of Variation

2011 ◽  
Vol 23 (8) ◽  
pp. 1944-1966 ◽  
Author(s):  
Susanne Ditlevsen ◽  
Petr Lansky
Keyword(s):  
Experimental Data ◽  
Standard Deviation ◽  
Coefficient Of Variation ◽  
Estimation Methods ◽  
Interspike Intervals ◽  
Estimation Errors ◽  
Empirical Standard Deviation ◽  
Receptor Neurons ◽  
The Mean ◽  
Empirical Standard

A convenient and often used summary measure to quantify the firing variability in neurons is the coefficient of variation (CV), defined as the standard deviation divided by the mean. It is therefore important to find an estimator that gives reliable results from experimental data, that is, the estimator should be unbiased and have low estimation variance. When the CV is evaluated in the standard way (empirical standard deviation of interspike intervals divided by their average), then the estimator is biased, underestimating the true CV, especially if the distribution of the interspike intervals is positively skewed. Moreover, the estimator has a large variance for commonly used distributions. The aim of this letter is to quantify the bias and propose alternative estimation methods. If the distribution is assumed known or can be determined from data, parametric estimators are proposed, which not only remove the bias but also decrease the estimation errors. If no distribution is assumed and the data are very positively skewed, we propose to correct the standard estimator. When defining the corrected estimator, we simply use that it is more stable to work on the log scale for positively skewed distributions. The estimators are evaluated through simulations and applied to experimental data from olfactory receptor neurons in rats.

At Least One Standard Deviation Above the Mean

1969 ◽  
Vol 14 (9) ◽  
pp. 470-471
Author(s):  
M. DAVID MERRILL
Keyword(s):  
Standard Deviation ◽  
The Mean
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