T, Y, plus and radial arm mazes

Arm mazes ask an animal to choose between paths. Olton and Samuelson's radial arm maze (1976) tested whether rats remember which arms they have already visited. The same tracking ideas apply to T, Y and plus mazes.

Multi-arm mazes in eight steps

Choose your maze type, click the maze points in the order shown, set the threshold, run, then pick a Detection Area for arm entries.

Make the background white for dark or hooded animals, or black for white animals, and plug in the camera first.
Click ‘Multi Armed Mazes’; if ‘3D-tracking mode’ is showing, click it to switch to ‘2D-tracking mode’.
Click ‘Calibrate’ and select your maze. Enter the height and width of the tracking area, click the points in the order shown in the small image (right-clicking the final point), check the outline appears, then click ‘Save (and return)’.
Click ‘Run’, select your maze and ‘Single Field’ on the ‘Maze Type’ tab, then on the ‘Tracking’ tab move ‘Set X-Y Threshold’ until the cross follows the animal (ignore ‘Set Z Threshold’).
On the ‘Configuration’ tab enter ‘Max secs’ and choose ‘Single Trial’ or ‘Series of Trials’.
On the ‘Run a Trial’ tab click ‘Prepare to Run’, place the animal and click ‘Run’; ‘End Trial’ stops early.
Click ‘Analyze’, select your maze type, choose the Detection Area and click ‘Analyze Single’.
For many trials use ‘Setup Custom’ with the maze variables and ‘Auto-Analyze’ to make a CST file.

More detail

At 100% Detection Area any entry counts; at 25% only entries to the far 25% of the arm. Per-arm data start from the left-most arm and go clockwise (plus maze: left, top, right, bottom).

You can re-analyse with different Detection Areas at any time, as long as you keep your .hvs files. For EPM, results include open versus closed % time and entries.

Arm entries, sequence and time per arm

Multi-arm results show which arms the subject entered, in what order, and how long it spent in each. The Detection Area sets how far into an arm the subject must go for an entry to count: at 100% any entry counts; at 25% only entries to the far 25% of the arm.

More detail

Per-arm data start from the left-most arm and go clockwise (plus maze: left, top, right, bottom). Measures include total arm entries, arms visited, entries per arm, latencies, % path and % time per arm and the entry sequence, and for EPM open versus closed % time and entries.

You can re-analyse with other Detection Area percentages at any time. Latency to an arm at 100% Detection Area appears in exports rather than on screen.

Reading multi-arm maze results (EPM, radial, T and Y mazes)

For the elevated plus maze, compare open-arm with closed-arm % time and entries; for radial, T and Y mazes, look at the entry sequence and repeat entries.

Typical control pattern: Elevated plus maze: rats made significantly fewer entries into the open arms than into the closed arms, and spent significantly less time in open arms (Pellow et al., 1985). Radial arm maze: rats performed efficiently, choosing an average of more than seven different arms within the first eight choices (Olton and Samuelson, 1976). T-maze: on the second of two quick trials the rodent tends to choose the arm not visited before (Deacon and Rawlins, 2006).
Signs of impairment: Elevated plus maze, anxiogenic-like profile: compounds that cause anxiety in man significantly reduced the percentage of entries into, and time spent on, the open arms (Pellow et al., 1985). T-maze: both spontaneous and rewarded alternation are very sensitive to dysfunction of the hippocampus (Deacon and Rawlins, 2006).
Signs of strong memory: Elevated plus maze, anxiolytic-like profile: an increase in open arm activity (duration and/or entries) reflects anti-anxiety behaviour (Walf and Frye, 2007).

Set-up problems that look like results

No tracking cross: check the background colour setting in calibration, then set Size just above zero and sweep the threshold slowly.
A trial lasting 0.1 s points to a mouse that double-clicks; try another.
Entry counts look wrong: check the Detection Area; at 100% any entry counts, at 25% only entries to the far 25% of the arm.

More detail

HVS Image lists per-arm data from the left-most arm clockwise, and for the elevated plus maze reports open versus closed % time and entries. You can re-analyse with other Detection Area percentages at any time, so report the one you used. Neither novelty nor illumination was a significant contributor to the behaviour of the rats on the plus maze (Pellow et al., 1985).

In the radial maze, there was a small but reliable recency effect, with the likelihood of a repetition error increasing with the number of choices since the initial instance (Olton and Samuelson, 1976). Pellow et al. (1985) found that neither antidepressants nor major tranquilisers had a specific effect on the plus maze.

Questions people ask

How do I calibrate a T, Y, plus or radial arm maze?

Click 'Multi Armed Mazes' > 'Calibrate', choose your maze and click the points shown in the small example image, in that order. 1) Enter user name, height and width. 2) Tick black only for light animals on a dark maze. 3) Click the points in order, using a right-click on the final point. 4) Check the maze outline appears, then 'Save (and return)'.

More detail

Click 'Multi Armed Mazes' (switch to '2D-tracking mode' if '3D-tracking mode' shows), plug in the camera first, click 'Calibrate' and select your maze type. Position the camera so the maze nearly fills the view. Enter user name and the height (top to bottom on screen) and width of the tracking area; tick black if subjects are light and the background dark. Click the points indicated in the small image on the right, in the order shown, then 'Save (and return)'. Keep the background white for dark or hooded animals and black for white animals, and make objects match the floor or mask them.

Going deeper

If calibration will not save: check Windows regional number formats are UK or USA and restart HVS; reselect the maze type (choose another then yours again); follow the example image; complete the full process including the right-click on the final point, after which 'Save (and return)' becomes available, and check the maze shape is drawn round the maze. Also check the USB camera is not disabled in Device Manager.

How do I set tracking and run multi-arm maze trials?

Run in 'Single Field' mode, set 'Set X-Y Threshold' until a cross follows the animal, then 'Prepare to Run' and 'Run'. 1) 'Run' > 'Maze Type' tab: your maze and 'Single Field' > 'Tracking' tab. 2) Ignore 'Set Z Threshold'; move 'Set X-Y Threshold' until a green or red cross tracks the animal. 3) On the 'Configuration' tab enter 'Max secs' and choose 'Single Trial' or 'Series of Trials'. 4) 'Prepare to Run', place the animal, 'Run'; 'End Trial' stops early.

More detail

On the 'Maze and Field Control Panel' click 'Run' (enter the tracking code if asked), choose your maze and 'Single Field' on the 'Maze Type' tab, then open the 'Tracking' tab. With trial lighting and objects in place, put an animal in, ignore 'Set Z Threshold' and move 'Set X-Y Threshold' until a green or red cross tracks it everywhere; use 'Set X-Y Size' to ignore the tail and droppings. Multi-arm mode runs one tracking area (1x1). On the 'Configuration' tab enter 'Max secs' and choose 'Single Trial' (enter Trial Name, User Name, Subject, Descriptor) or 'Series of Trials' (a .txp file in Master Experiment Files, lines like ,,mouse1,groupA, chosen with 'Choose TXP/MEF'). Click 'Prepare to Run', place the subject and click 'Run'.

Going deeper

No tracking cross: check the background colour setting in calibration, then set Size just above zero, sweep the xy slider slowly to find where the cross appears, set Size to body width and fine-tune. A trial lasting 0.1 s points to a mouse that double-clicks; try another.

How do I analyse arm entries and what is the Detection Area?

Choose a Detection Area (the % of each arm that counts as an entry), then analyse; arms are listed from the left arm clockwise. 1) 'Analyze' > select your maze. 2) Pick e.g. 100% (any entry) or 25% (far quarter only). 3) 'Analyze Single' for one trial; 'Setup Custom' (Maze Variables) and 'Auto-Analyze' for batches. 4) Re-analyse with other percentages any time.

More detail

In 'Analyze' select your maze type; keep Video Height/Width at 480/640 for live trials. Select the Detection Area, the percentage of the arm for which entries are counted: at 100% any entry counts; at 25% only entries to the far 25% of the arm. Grid cells are not used. 'Analyze Single' shows a trial's results; per-arm data start from the left-most arm and go clockwise (plus maze: left, top, right, bottom). Print or Export saves a text file. For batches: 'Setup Custom', name the CST, tick items, ignore 'Field Variables', tick 'Maze Variables', 'Save Spec', select CST and trials, 'Auto-Analyze'. CSTs are in …\Data\Multi Arm Mazes\CST, one row per trial with per-arm columns.

Going deeper

Measures include average speed, total arm/area entries, arms visited, entries per arm, latencies, % path and % time per arm, entry sequence, and for EPM open versus closed % time and entries. Latency to an arm at 100% Detection Area appears in exports rather than on screen. Decision time can be taken from video frames or from X/Y changes in the .hvs.

See HVS Image for multi-arm mazes, including the radial arm maze.

Sources

Olton & Samuelson (1976). Remembrance of places passed: Spatial memory in rats. Journal of Experimental Psychology: Animal Behavior Processes 2(2):97-116. doi:10.1037/0097-7403.2.2.97

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