Event-related parameters

The following event-related parameters are available for display/analysis through the screen numerical display, the event parameter list/save facility, the histogram facility and the 2- and 3-D scattergraph facilities.

Note that not all parameters are available in all facilities.


Event-specific parameters

These parameters are intrinsic to the events themselves, and do not require measurements from any data trace.

Single-channel properties

Event ID: The identification number ( 1 - ...) of a particular event.

On time: The onset time of the event.

On time (elap): The onset time of the event relative to elapsed experimental time.
      For episodic files, this will be the time elapsed from the start of the episode plus the start time of the episode itself.
      For non-episodic files, this will be the same as the simple On time parameter above.

Duration: The duration of the event.

Num samples: The number of data samples within the event.

Gap duration: Durations of the gaps between events

Frequency (instantaneous): The instantaneous frequency (in Hz) of an event, calculated as the reciprocal of the time interval between the start of that event and the start of the preceding event. The frequency of the first event is undefined, but is often displayed as the same as that of the second event.

Frequency in time bin: The recording, or a section of the recording, is divided into a sequence of contiguous time bins. The number of events whose start times fall within each bin is divided by the bin width (in seconds) to calculate the average frequency of events within the bin.

Interval: The interval between the start of an event and the start of the preceding event. The interval of the first event is undefined but is often displayed as the same as that of the second event.

Duty cycle: The fraction (0 - 1) that an event occupies in its current cycle. This is calculated as the event duration, divided by the time from the start of the event to the start of the next event (the cycle period). The duty cycle of the last event is undefined, but is often displayed as the same as that of the preceding event.

Distribution count: This generates an event count distribution display, and is only available from the Event analysis: Histogram command. The selected region of data is divided into successive time bins of duration specified by the Distrib bin (ms) parameter visible in the Histogram dialog.

Count in time bin: The recording, or a section of the recording, is divided into a sequence of contiguous time bins. The number of events whose start times fall within each bin is calculated.

Auto-correlogram: This applies to Histogram displays. It shows the number of events within each bin on the condition that there is an event in the same channel at time zero. It differs from the interval parameter in that it considers intervals between all pairs of events whose inter-event interval occurs within the time set by the X axis scales, irrespective of whether other events have intervened.

Tagged: Shows T (true) or F (false) to indicate whether the event has a tag.

Label: Shows the event label. Blank if no label.

Colour (hex value): Shows the event colour as a hexadecimal RGB value.

Surprise: The surprise value of events detected using the Poisson or Rank surprise method for burst detection. Only relevant for event channels populated using this method.

Dual-channel properties

Phase (1 in 2): The phase of the start of each event in the target event (1) channel relative to the starts of the pair of surrounding events in the reference (2) channel. Thus phase represents the fraction of the time between two successive reference events at which an intervening target event occurs. Phase is greater than or equal to 0, and less than 1. Target events preceding the first or following the last reference event are ignored.

PSTH (2->1): This generates a peri-stimulus time histogram, and is only available from the Event analysis: Histogram command. Events in channel 2 mark the stimulus and events in channel 1 mark the response to the stimulus. The response latency is calculated relative to the stimulus, and pre-stimulus time can be included as control data. This is similar to cross-correlogram (2->1), except that stimulus events must be further apart than the largest specified histogram range, so that each response corresponds to a unique stimulus. The facility also allows you to collate response counts on a per-stimulus basis, so that the mean and standard deviation of counts per stimulus can be displayed.

Latency (1 after 2): The latency from the start of each event in the reference (2) channel to following events in the target event (1) channel, up to the next reference event. Latency is greater than or equal to 0, and less than the interval between the reference event and the immediately following reference event (i.e. latency resets with each reference event).

Latency (1 from near 2): The latency from the start of each event in the target event (1) channel to the nearest event, either preceding or following, in the reference (2) channel. Latency can thus be either positive or negative.
There will always be the same number of latencies as there are events in the target channel.

Latency (1 from 2 paired): The latency from the start of each event in the target event (1) channel to the start of the event with the same ID number in the reference (2) channel. Latency can be either positive or negative.
Unpaired events are ignored.

Count (2 in 1): The count of events in the channel 2 which are entirely within the duration of events in the channel 1. A value is thus available for each event in channel 1. When displayed in a histogram, the X axis (bins) shows the number of enclosed channel 2 events, the Y axis shows the number of events in channel 1 which have that number of enclosed channel 2 events.

Stats (2 in 1): Show statistics of events in channel 2 which are entirely within the duration of events in channel 1. Statistics are thus available for each event in channel 1.

Count (2 after 1): The counts of events in channel 2 which follow after each event in channel 1. Counting is terminated when the off-time of a channel 2 event is later than the on-time of the next channel 1 event. When displayed in a histogram, the X axis (bins) shows the number of channel 2 events following a channel 1 event, the Y axis shows the number of events in channel 1 which have that number of following channel 2 events.

Cross-correlogram (2 -> 1): This applies to Histogram displays. It investigates the "influence" that events in a reference channel (channel 2) have on the probability of occurrence of events in a target channel (channel 1). Specifically, it shows the number of target events in channel 1 within each bin on the condition that there is an event in reference channel 2 at time zero. It thus shows the probability of occurrence of target events at various times relative to reference events. Effectively, peaks/troughs at positive latencies indicate the possibility of a connection from the reference to the target data source. It differs from the latency parameter in that it considers all events in the target event channel whose latency from the reference channel occurs within a time set by the X axis scales, irrespective of whether other reference channel events have intervened.

 

Data-specific parameters

These parameters involve measuring data from the parent trace of the event.

 

P2P amplitude: Maximum peak-to-peak amplitudes within events.

P2P duration: Absolute value of the time intervals between the maximum positive and negative peaks within events.

MaxT - MinT: The time between the maximum positive and negative peaks within events. May be positive (peak before trough) or negative (trough before peak). A signed version of P2P duration.

Max: The maximum value within the event in the parent trace of the event

Min: The minimum value within the event in the parent trace of the event

Normal statistics (Avg, S.D): The mean value and standard deviation of data within the event in the parent trace of the event

Robust statistics (Median, MAD, robust S.D.): The median value, median absolute deviation from the median (MAD) and robust standard deviation of data within the event in the parent trace of the event. The robust standard deviation is taken as the MAD multiplied by 1.4826.

Area: The area (integrated values) within the event in the parent trace of the event

Slope: The linear regression slope of data within the event. Expressed as change in amplitude per second.

RMS: The root-mean-square of data within the event.

Energy (relative): The sum of the squared data values throughout the event, normalized to time by multiplying by the sample interval.

Autocorr rhythm info (rhythmicity idx, period): Perform a statistical autocorrelation (normalized autocovariance) analysis of the waveforms within each event, and determine the index of rhythmicity (the first trough to second peak height) and the period (lag to second peak).

PC 1-3 weight: Coefficient of the first, second or third principal coordinate. If principal components have not previously been calculated with the Event analyse: Principal component analysis command, then you will be asked whether you wish to calculate them.

Val at time A, B, C: The values of data at 3 different times within events. The times are specified in auxiliary program components.

DWT A, B, C: The value of the discrete wavelet transform coefficient of data within the event at times A, B and C. The times and wavelet characteristics are specified in auxiliary program components.

Template Error: The error between the waveform of the parent trace within this event and the template used in the Template recognition method of detecting events. Only relevant for event channels populated using this method.