Table 2. Definitions of primary and secondary proxies from the TracMouse system.
| TracMouse parameters | Definition |
|---|---|
| Cling Time | Overall time in which animal kept contact with a grid (latency to fall; max 30 s) |
| Hold | Time with all digits seizing the grid wire and XY coordinates being constant |
| Total number of Holds* | Total number of Hold episodes during the trial |
| Holds duration *[s] | Total time in Hold during the trial |
| Mean duration per Hold [s] | Holds duration/Total number of Holds |
| Step without Touch | Paw displacement from given XY coordinates of a given Hold to new XY coordinates of the next Hold;(if a Step includes a Touch see below) |
| Total number of Steps without Touches* | Number of completed Steps during the given trial without Touches |
| Steps duration*[s] | Cumulative time spent in Step mode during triala |
| Steps distance*[mm] | Cumulative distance of all Steps during triala |
| Mean Step duration [s] | Steps duration/Total number of Steps without Touches |
| Mean Step length [mm] | Steps distance/Total number of Steps without Touches |
| Mean Step velocity [mm/s] | Step distance/Total number of Steps without Touches |
| Touchb Step with Touch(es)b | During Step, a paw makes contact with grid; however the phalanges do not perform a grip but the paw moves on to a different XY coordinate or returns to its original location (exploratory steps with touches) |
| Total number of Touches* | Total number of Touches during trial |
| Total number of Steps with Touches* | Total number of Steps with one/multiple Touches |
| Wall Contact | A paw makes contact with the wall |
| Total number of Wall Contacts* | Total number of Wall Contacts per trial |
| Wall Contacts duration* | Cumulative time spent in Wall Contact mode during trial |
| Train | Series of Steps (≥2) of the same forepaw |
| Number of Trains* | Number of occurrences of Trains per trial |
| Steps per Train | Total number of Steps without Touches /Number of Trains |
| Regularity Index | The number of peaks (local maxima) in the time course curve of Step length, where on X axis no. of Step, on Y axis its length in mm, divided by ½ (Total number of Steps without Touches -1) |
Note that most of these parameters can be individually calculated for each paw.
Explanations:
*Denotes parameter normalization i.e. division by Cling Time and multiplication by nominal length of the trial i.e. 30 s.
aOnly Steps without Touches.
bOnly applies to forepaws.