Knowledge Base

Analyze Data

Sub Print View

The Sub Print View shows the individual prints of the Stand. The time between two subsequent prints is 1/100 s.

Base of Support

Base of Support is the average distance between either the front paws or the hind paws, measured along the y axis. Choose Analyze > View Run Statistics and under Statistics click Base of Support.

In the Base of Support sheet the following variables/parameters are displayed:

• Paw – The label of the paw.
• N – The number of times each paw was placed.
• Mean (in Distance Unit) – The mean value for the Y position for each paw.
• SEM (%) – This is the Standard Error of the Mean, expressed as a percentage of the mean Base of Support.

At the bottom:

• Paws – Front paws or Hind paws.
• N – The total number of times the paw combinations were placed.
• Base of Support ([Distance Unit]) – The mean distance between either front paws or hind paws. The Base of Support is calculated as follows:
  • Base of Support Front paws = |YRF − YLF|
  • Base of Support Hind paws = |YRH − YLH|

The Base of Support parameter is used in research on spinal cord injury. It has been found that as a result of trauma to the spinal cord (either as a result of a transection or contusion), the Base of Support of the front paws is unaffected, but that of the hind paws showed an increase (Hamers et al., 2001).

Other Statistics

In the Other Statistics sheet, the following parameters are displayed:

Duration

This is the duration of the run based on the selected steps in the data selection. The Duration is different from the Run Duration, which is the duration of the recorded run.

Average Speed

This is the average speed of the selected steps in the data selection. The Average Speed is expressed in Distance Units per second.

Maximum Variation (%)

This is the Maximum Variation in average speed of the selected steps in the data selection.

Cadence

The Cadence is expressed in steps per second:

Cadence = (# steps − 1) / (Initial Contact last Stand − Initial Contact first Stand)

The selected steps include the yellow, unaccounted steps in the Footfall Patterns diagram, but the steps that are not selected in the current Data Segmentation profile are not included.

Number of Steps

This is the total number of selected steps in this run. Steps that are not selected in the current Data Segmentation profile are not included.

Sciatic Functional Index

The Sciatic Functional Index (SFI) is a measure for the functional recovery of the sciatic nerve which innervates the hind paws. Therefore, the SFI is only relevant for hind paws. The SFI is calculated differently for rats and mice.

The formula used for the calculation of the SFI for rats (Bain et al., 1989):

SFI = −38.3 × ((PLE − PLN) / PLN) + 109.5 × ((TSE − TSN) / TSN) + 13.3 × ((ITSE − ITSN) / ITSN) − 8.8

where PL is Manual Print Length, TS is Toe Spread, ITS is Intermediate Toe Spread, and the subscripts E and N indicate the Experimental and Normal contralateral hind paws, respectively.

The formula used for the calculation of the SFI for mice (Inserra et al., 1998):

SFI = 118.9 × ((TSE − TSN) / TSN) − 51.2 × ((PLE − PLN) / PLN) − 7.5

Note: Although ITS is not in the formula above, you need to measure the ITS in mice in order to have the SFI calculated.

Posterior Tibial Functional Index

The Tibial Functional Index (TFI) is a measure for the functional recovery of the tibial nerve, which is a branch of the sciatic nerve.

The formula used for the calculation of the TFI for rats (Bain et al., 1989):

TFI = −37.2 × ((PLE − PLN) / PLN) + 104.4 × ((TSE − TSN) / TSN) + 45.6 × ((ITSE − ITSN) / ITSN) − 8.8

where PL is Manual Print Length, TS is Toe Spread, ITS is Intermediate Toe Spread, and the subscripts E and N indicate the Experimental and Normal contralateral hind paws, respectively.

The formula used for the calculation of the TFI for mice (Inserra et al., 1998):

TFI = −109.9 × ((PLE − PLN) / PLN) − 7.2

Peroneal Functional Index

The Peroneal Functional Index (PFI) is a measure for the functional recovery of the peroneal nerve which innervates the hind paws.

The formula used for the calculation of the PFI for rats (Bain et al., 1989):

PFI = 174.9 × ((PLE − PLN) / PLN) + 80.3 × ((TSE − TSN) / TSN) − 13.4

where PL is Manual Print Length, TS is Toe Spread, and the subscripts E and N indicate the Experimental and Normal contralateral hind paws, respectively.

The formula used for the calculation of the PFI for mice (Inserra et al., 1998):

PFI = 191.1 × ((TSE − TSN) / TSN) − 9.86

where TS is Toe Spread and the subscripts E and N indicate the Experimental and Normal contralateral hind paws, respectively.

Print

Print displays all non-paw prints (Right Hip, Right Knee, Left Hip, Left Knee, Nose, Abdomen, Tail, Genitalia). For each print the following is given:

• Number of Contacts – With the glass plate.
• Total Duration – Of contact with the glass plate.
• % – Total Duration of contact with the glass plate expressed as a percentage of the total Duration (time between first selected print and last selected print of the run).

Print Positions

Print Positions is the distance between the position of the hind paw and the position of the previously placed front paw on the same side of the body (ipsilateral) and in the same Step Cycle.

• A positive value of Print Positions indicates that the hind paw is placed behind the front paw.
• A negative value of Print Positions indicates that the hind paw is placed in front of the front paw.

The Print Positions sheet shows the distance (in the selected Distance Units) for the right and left front paws and their respective ipsilateral hind paws. Calculation of Print Positions is based on the X-coordinates of the centers of ipsilateral paws at Max Contact.

• Walking direction from left to right: Print Positions = XFP(Max Contact) − XHP(Max Contact)
• Walking direction from right to left: Print Positions = XHP(Max Contact) − XFP(Max Contact)

where FP is one of the front paws and HP is one of the hind paws.

The last front paw does not have a Step Cycle (and therefore no Print Position), but if the corresponding hind paw starts within the Stance of the front paw, this combination is also used for calculating the Print Position.

In the Print Positions sheet, when you click one of the front paw rows:

• The Print View highlights the ipsilateral paws.
• The Timing View shows the Stand of both ipsilateral paws.

Phase Dispersions

The Phase Dispersions parameter describes the temporal relationship between placement of two paws within a Step Cycle. It is used as a measure of inter-paw coordination.

Calculation

Phase Dispersions is the moment of Initial Contact of a target paw expressed as a percentage of the Step Cycle time of an anchor paw. Phase Dispersions range from −50 to 75%.

The formula for Phase Dispersions is:

Phase Dispersions = ((ICtarget(m) − ICanchor(n)) / Step Cycle anchor) × 100%

where IC is Initial Contact.

A positive Phase Dispersions value indicates that initial contact of the target paw occurred after that of the anchor paw. A negative Phase Dispersions value indicates that the target paw preceded the anchor paw.

Phase Dispersions can be computed for a total of 12 pairs. However, interchanging target and anchor does not have a large effect since their Phase Dispersions values are normally strongly correlated, so only 6 pairs of paws are displayed. Within diagonal pairs (RF-LH, LF-RH) and ipsilateral pairs (RF-RH, LF-LH), the anchor is always one of the front paws. Within girdle pairs (LF-RF, LH-RH), the anchor paw is always one of the left paws.

Which paws/parameters are displayed in the Phase Dispersions sheet depends on the selection in the currently active Parameter profile (displayed in bold and blue in the Experiment Explorer).

Statistics

The following statistics are displayed in the Phase Dispersions sheet for the various paw combinations:

• Value – This column shows the Phase Dispersions values. An empty cell indicates that Phase Dispersions could not be calculated.
• Anchor Start (A-Start) – Initial Contact of the anchor paw. An empty cell indicates that Phase Dispersions could not be calculated.
• Anchor Duration (A-Duration) – The duration of Step Cycle of the anchor paw.

Stand for each paw is depicted by a black bar and Swing is shown as a white bar. Initial Contact is the point of transition from the white to black bar. A Step Cycle runs from Initial Contact to the next Initial Contact of that paw. Phase Dispersions is calculated by measuring the timing between Initial Contacts of a paw pair (RF–RH) and expressing it as a percentage of the Step Cycle time of the anchor paw (RF). For example, if Initial Contact of the RH (target paw) occurs 0.22 s after that of the anchor paw (RF) and the Step Cycle is 0.44 s, the resulting Phase Dispersions value is 50% (0.22/0.44 × 100). If the Phase Dispersions value exceeds 75% with the first anchor, the target is assigned to the next anchor (Kloos et al., 2005).