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Spike Sorting
Note:
For stereotrode and tetrode data, the sort range is specified per-electrode, not
for the concatenated waveform.
4.4.6 Selecting Features to Use For Sorting
For those sorting methods that use feature space (i.e. all methods except
Waveform Crossing and Templates), one must first decide which feature space to
work in. One does this by selecting particular features for each of the 2 (for the
2D Clusters view) or 3 (for the 3D Clusters view) axes in feature space (See
Section 6.4, "Features Available for Sorting” on page 294.). Offline Sorter
Software does all spike sorting and calculates all statistics in the feature space
selected, so the objective is to find a combination of features that gives maximal
cluster separation. The description in Section 3.13, "Feature vs. Feature View” on
page 80 can be useful in selecting which features to use.
First, select either the 2D Clusters view or the 3D Clusters view using the View
menu command or the toolbar buttons
or
.
Then, select features for the X, Y, (and Z) axes from the drop-down lists on the
toolbar:
Note:
Only the “active” features appear in the drop-down lists, which are a subset of
all features. Use the Active Features tab of the Tools | Options dialog box to
select which features are active. For more information, see Section 3.7.2,
"Clusters Views Common Functionality” on page 54.
When switching channels within the currently-opened data file, the selected
features can either be “remembered” on a per-channel basis, or the same feature
space can be used across all channels. You can control this by the Remember
selected features for each channel checkbox in the Tools | Options | Feature
Calc dialog box.
If the sorting algorithms are used, remember that they work differently in 2D and
3D feature space. The feature space that the algorithms use depends on the active
view when the sorting operation initiates. See Section 6.5.1, "Feature Space Used
for Sorting” on page 299.
4.5 Spike Sorting
Finally, the waveforms can now be sorted into units. Offline Sorter Software
offers several methods to accomplish this.
4.5.1 Manual, Semi-Automatic, and Automatic Clustering Methods
Offline Sorter Software offers manual, semi-automatic, and automatic methods to
identifying units or clusters.
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