Elevated plus maze

The question

Picture the set-up for a second. How does a raised cross of four arms measure anxiety-like behaviour? You're watching Morris Water Maze Software Guide, over at morriswatermazesoftware.com.

Meet the elevated plus maze

The elevated plus maze is a plus-shaped platform raised above the floor, with two open arms and two arms enclosed by walls. Rodents prefer the closed arms, and anxiety-reducing drugs increase visits to the open arms. A 1985 study validated open to closed arm entries as a measure of anxiety in the rat.

How it runs

Let me walk you through it. First, light the maze evenly and keep the room quiet. Next, place the animal in the centre, facing an open arm. Then, record for five minutes. Finally, clean the maze between animals.

Strengths and limits

So what's in it for you? Fast, with no training. Well validated with decades of drug studies. Open and closed arm measures come from one short session. Where does it bite? It's sensitive to handling, lighting and test order. Repeat testing changes behaviour, so it's usually a one-time test.

What to measure

Let's open up the analysis. Percentage of time in open arms: the main anxiety-like measure. Open arm entries as a share of all entries: the measure validated in 1985. Total entries and distance: a check on general activity. Head dips and stretched-attend postures: risk assessment behaviours. A drug raises open-arm time. Good news? Check total entries first. If the animals are simply more active everywhere, the open-arm gain may not mean lower anxiety at all.

The takeaway

Short version: open arm entries as a share of all entries and its neighbours tell you how the task was done, not just how fast. The full transcript is on this page, with sources.