The complexity of exploratory behavior creates a need for a visualization and analysis tool that will highlight regularities and facilitate the generation of new hypotheses and algorithms of quantification. SEE is a program developed by us for this aim. The raw data for SEE are a time series of the animal's coordinates in space, sampled at a rate that permits a meaningful computation of velocities (~10 Hz).

Figure 1. A path plot created by a hooded rat in a 6.50 m diameter arena during a 20 min session (left) and an analysis of that path into segments (right). "Bubbles" represent stops, where the size of the bubble stands for stop duration. Movement segments are represented as straight lines that connect the start and end points of the segment, regardless of the actual path. The analysis on the right highlights home base location and the straight lines highlight the home base's high connectivity to most of the arena.

SEE provides:

• Visualization of the path of the animal and a computation of the dynamics of activity (PathPlot, see Figure 1).
• Visualization of the decomposition of the path into several modes of motion (e.g. 1st gear, 2nd gear, 3rd gear; see [1]) and the computation of typical speed, spatial spread, and proportion of each of these gears.
• Visualization of the location of stopping episodes [3] together with a representation of the duration of each episode (TimePlot). This highlights the home base phenomenon [2] and permits a computation of the spatio-temporal diversity of stopping episodes [4].
• Decomposition of the animal's path into "excursions" and computation of the number of stops per excursion [3].
• Visualization of the phase space (path + velocity in the third dimension) of any segment or list of segments.
• Visualization of the way places in the animal's operational world (as highlighted by TimePlot) are connected one to the other, as well as any subset defined through computable properties (To[place], From[place], etc.).

We will demonstrate the properties of SEE on our computer demo both on our own and other laboratories' data, provided data files are sent to us for examination and preparation (smoothing and initial segmentation), and found appropriate, 6 weeks ahead of time. EthoVision track files are welcome, as well as any other format consisting of a time series of coordinates in a machine-readable form.

This project is supported by NIH grant 1 R01 NS40234-01.

References

1. Drai, I.; Benjamini, Y.; Golani, I. (2000). Statistical discrimination of natural modes of motion in rat exploratory behavior. Journal of Neuroscience Methods , 96, 119-131.
2. Eilam, D.; Golani, I. (1989). Home base behavior of rats (Rattus norvegicus) exploring a novel environment. Behavioral Brain Research, 34, 199-211.
3. Golani, I.; Benjamini, Y.; Eilam, D. (1993). Stopping behavior: Constraints on exploration in rats (Rattus norvegicus). Behavioral Brain Research, 53, 21-33.
4. Tchernichovski, O.; Benjamini, Y.; Golani, I. (1996). Constraints and the emergence of freedom in the ontogeny of rat exploratory behavior. Behaviour, 133, 519-539.

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