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Combine and Compare Peri-Event Analysis Data

Compute Credits

This tool uses 1.0 compute credits per hour.

Overview

This tool is used to combine peri-event analysis data from multiple recordings and perform a statistical comparison between two groups to determine if there is a difference in the fractions of up- or down-modulated neurons.

Parameters

Parameter Required? Default Description
Peri-Event Traces Files True N/A Select peri-event traces from the first group to use for analysis
Peri-Event Statistics Files True N/A Select peri-event statistics from the first group to use for analysis
Name True group1 Name of the first group
Peri-Event Traces Files False N/A Select peri-event traces from the second group to use for analysis
Peri-Event Statistics Files False N/A Select peri-event statistics from the second group to use for analysis
Name False N/A Name of the second group
Comparison Type False N/A Type of statistical test to perform
Data Pairing False N/A Indicates whether observations should be paired for statistical comparison
Significance Threshold False N/A p-value threshold for classifying neurons as up- or down-modulated
Average Method True neurons Specifies how to average the data in each input group. If 'By Neurons' is selected, the neurons from all recordings in the group will be pooled together and averaged to obtain the group average. If 'By Recordings' is selected, the data contained in each recording will be averaged independently, then the recordings will be averaged together to obtain the group average.
Tolerance True 0.01 Maximum time shift in seconds between the time windows of the input traces files
Population activity (y-axis range) False auto y-axis range (z-score) applied to the event-aligned population activity plot specified as 'min,max' (e.g. -1,1) or 'auto'
Activity heatmap (colormap range) False auto colormap range (z-score) applied to the activity heatmap specified as 'min,max' (e.g. -1,1) or 'auto'
Activity by modulation group (y-axis range) False auto y-axis range (z-score) applied to the event-aligned activity by modulation plot specified as 'min,max' (e.g. -1,1) or 'auto'

Valid Inputs

Source Parameter File Type File Format
Peri-Event Traces Files neural_traces, event_aligned_neural_data csv, csv
Peri-Event Statistics Files statistics csv
Peri-Event Traces Files neural_traces, event_aligned_neural_data csv, csv
Peri-Event Statistics Files statistics csv

Algorithm Description

The workflow is summarized using a flowchart below.

graph TD A[Combine peri-event analysis data from first group] --> C[Compare data from two input groups]; B[Combine peri-event analysis data from second group] --> C[Compare data from two input groups];

The workflow begins by combining the data in the first input group. If no data is selected for the second input group, the workflow terminates upon combining the data from the first group. If data is selected for the second group, that data will be combined independently of the first group. Finally, the two groups are compared to determine if there is statistically significant difference between them.

Combination

The combination step is performed independently for each input group. The process starts with the alignment of time windows across the input files. If the difference between the time windows is within the specified tolerance, the algorithm will align the time points across the input files and trim off excess time points. The data from all recordings in the group is then aggregated, creating a population of cells. Individual cells are classified as up-, down-, or non-modulated based on the significance threshold parameter. The fraction of up-, down-, and non-modulated neurons across the aggregated population of cells is computed. The event-aligned population activity is obtained by averaging the neural activity at each time point. When averaging across neurons, neurons from all recordings in the group are pooled together and averaged to obtain the group average. When averaging across recordings, the data is first averaged across neurons for each recording, yielding a single average trace per recording. The recording traces are then averaged together to obtain the group average. Likewise, the event-aligned sub-population activity is obtained for each modulation category (up-modulated, down-modulated, non-modulated) by averaging the neural activity of the corresponding cells.

Comparison

The fraction of up-, down-, and non-modulated neurons is computed for each recording. A t-test is then performed to compare the means of the two groups for each modulation category (up-modulated, down-modulated, non-modulated). The t-statistic and corresponding p-value is reported for each statistical test. We specifically test for the null hypothesis that the two groups have identical average values. The alternative hypothesis tested is determined by the comparison type parameter as described in the table below.

Comparison Type Hypothesis Tested
One-Tailed (Less) fraction of modulated neurons in the first group is less than the second group
One-Tailed (Greater) fraction of modulated neurons in the first group is greater than the second group
Two-Tailed (Unequal) fraction of modulated neurons in the first group is different from the second group, i.e. fraction of modulated neurons in the the first group is either less than or greater than the second group

Output Figures

Combination Figures

Comparison Figures

Legend

Panel Description
A, E Event-aligned activity heatmaps of the first and second groups, respectively.
B, F Event-aligned population activity of the first and second groups, respectively.
C, G Event-aligned sub-population activity of the first and second groups, respectively.
D, H Pie chart showing the fraction of up-, down-, and non-modulated neurons in the first and second groups, respectively.
I Comparison of event-aligned sub-population activity between the two input groups.
J Comparison of event-aligned population activity between the two input groups.
K Comparison of the fraction of neurons in each modulation category between the two input groups. The mean ± sem is plotted along with the individual data points, each representing a recording session.

Output Data

Combination Data

For each input group, two files are produced during the combination step. The two files are equivalent to those produced by the peri-event analysis workflow.

Event-Aligned Traces

A csv file containing the event-aligned activity of all cells as well as the activity of the population and sub-populations.

Event-Aligned Statistics

A csv file containing the data used to perform statistical tests for each cell along with corresponding statistics and modulation classification.

Comparison Data

A single csv file containing a summary of the statistical tests performed.