update metric docs

Author: JaerongA

notebooks/quality_metrics.ipynb

@@ -62,7 +62,7 @@
     "| Firing rate (Hz) | Total number of spikes per second. |\n",
     "| Signal-to-noise ratio | Ratio of the maximum amplitude of the mean spike waveform to the standard deviation of the background noise on a given channel. |\n",
     "| Presence ratio | Proportion of time during a session that a unit is spiking, ranging from 0 to 0.99. |\n",
-    "| Interspike interval (ISI) violation | Rate of ISI violation as a fraction of overall rate. |\n",
+    "| Interspike interval (ISI) violation | Rate of inter-spike-interval (ISI) refractory period violations. |\n",
     "| Number violation | Total number of ISI violations. |\n",
     "| Amplitude cut-off | False negative rate of a unit measured by the degree to which its distribution of spike amplitudes is truncated, indicating the fraction of missing spikes. An amplitude cutoff of 0.1 indicates approximately 10% missing spikes. |\n",
     "| Isolation distance | A metric that uses the principal components (PCs) of a unit's waveforms, which are projected into a lower-dimensional PC space after spike sorting. This quantifies how well-isolated the unit is from other potential clusters. |\n",
@@ -72,6 +72,7 @@
     "| Nearest-neighbors miss rate |  The proportion of its nearest neighbors that do not belong to the same given cluster based on its first principal components. |\n",
     "| Silhouette score | The ratio between cohesiveness of a cluster (distance between member spikes) and its separation from other clusters (distance to non-member spikes). |\n",
     "| Max drift | The maximum shift in spike location, calculated as the center of mass of the energy of the first principal component score. |\n",
+    "| Cumulative drift | The cumulative change in spike position throughout a recording. |\n",
     "\n",
     "For further details of the quality metrics, please see:\n",
     "- [Allen Institute Documentation](https://allensdk.readthedocs.io/en/latest/_static/examples/nb/ecephys_quality_metrics.html)\n",