Methods of calculating whisking parameters
| Variable name | Method of calculation |
|---|---|
| Continuous variables | |
| Position | Angular position of the whiskers was calculated in both snout and world coordinates (see Fig. 1B). The angular position of the head was only meaningful in world coordinates. |
| Velocity | Angular velocity of the whiskers (head) was calculated as the time derivative of the angular position of the whiskers (head). |
| Angle of symmetry | The angle of symmetry was defined as the angle about which the whisker arrays were symmetric in world coordinates. |
| Array extent | Array extent for the right (left) side was calculated as the difference in the angular positions of the rostral and caudal whisker for the right (left) side. |
| Discrete variables | |
| Protraction set point | Protraction set point was defined as the angle at which the protraction ended and retraction began. (The rat protracted its whiskers to the protraction set point.) |
| Retraction set point | Retraction set point was defined as the angle at which the retraction ended and the next whisk began. (The rat retracted its whiskers to the retraction set point.) |
| Protraction amplitude | Protraction amplitude was defined as the difference between the retraction set point of the previous whisk and the protraction set point of the current whisk. |
| Retraction amplitude | Retraction amplitude was defined as the absolute value of the difference between the protraction and retraction set points of that whisk. |
| Protraction time | Protraction time was defined as the time of peak protraction, that is, the time when protraction ended and retraction began. If the protraction set point was maintained for more than one frame, the average time of peak protraction was taken. |
| Retraction time | Retraction time was defined as the time of peak retraction, that is, the time when retraction ended and the next whisk began. If the retraction set point was maintained for more than one frame, the average time of peak retraction was taken. |
| Protraction and retraction durations | Protraction and retraction durations were defined as the length of time it took the rat to perform the protraction or retraction, respectively. |
| Protraction and retraction velocities | Protraction and retraction velocities were defined as the average velocity over a protraction or retraction, respectively. Velocities were calculated by dividing the amplitudes by the durations. |
| Protraction and retraction time differences | The protraction (retraction) time difference between the right and left whisker arrays was defined as the difference between the times of peak protraction (retraction) on right and left sides. |
See Figure 1D for a schematic of these parameters.