The Atlantis (rising) platform

Do not connect the platform to mains power; use only the control box provided. The power is low voltage but the cable connectors are not designed for water, so keep them outside the pool. Without power, the magnet under the platform top strongly attracts the base electromagnet, so avoid letting them snap together, especially out of water. Older Atlantis models use a control tower with a rechargeable LiPo battery instead: keep the tower switch in the middle except for a release of a second or less (holding release drains the battery and can damage the battery and electromagnet coils), and charge it only with the balance charger on its 'LiPo BALANCE' setting.

Going deeper

The current control box runs on a 9 V PP3 battery that you replace before it runs flat; the older tower's LiPo battery is balance-charged with the tower switched to charging, and its switch stays in the middle except for a split-second release. If you are not sure which model you have, ask HVS.

The platform arrives pre-assembled, typically 30 cm high when raised, to suit 30 cm of water. Height is set by collars fixed with grub screws on the rods along which the top slides. Reach the grub screws through the holes in the platform top with the supplied 3 mm hex wrench, loosen just enough to slide the rod through the collar, and retighten. Keep a finger inside to locate the rod and collar so the screw or collar does not fall out.

Going deeper

Set the raised height so the top sits just below the water surface. Web product information gives a vertical range of about 23–35 cm for the standard Atlantis; for other depths, contact HVS.

When you first submerge the platform in a session, turn it sideways to partly fill the top with water, then test whether the top sticks to the base when pushed down. If it bobs up, add a little more water and retest. If it does not bob up with a gentle upward pull, it needs more air. The right balance is when it stays down if tapped from the side but lifts easily with a very gentle pull. If it is close but lifts a little too easily, push it down firmly and count to two on contact; if it still bobs up, release a little air by tilting it underwater.

Going deeper

The adjustability compensates for fouling of the magnetic contacts by substances in the pool, including whitener. Connect the control box to the tracking PC by the supplied USB cable and use the standard (not VR) Morris water maze instructions.

On the Morris Water Maze run screen, click the button at the bottom right until 'USB on End' shows (its other states are 'Auditory Off', 'Tone on Swim' and 'Tone on End'). Under 'Auto-end on platform' choose 'Delay in Secs' for a dwell time, or 'Yes' to rise as soon as the subject reaches the target area. The platform then rises when the subject reaches the platform location defined by your calibration and the trial's platform number. Between trials push it gently down so the magnets hold it.

Going deeper

The target area that triggers release is set in Calibration and can be equal to, larger or smaller than the physical platform, depending on how precisely the subject must locate the position. Clicking the button moves it to the next mode, so check it still reads 'USB on End'. If there is no click from the control box at trial end, try the other USB ports in turn. If Atlantis is used with a dwell during training, use it in probes too (with a slightly longer dwell) so it is not found by chance.

To raise the platform manually, select 'No' under 'Auto-end on platform'; the platform rises when you click 'END'. In non-automatic mode set at regular height, Atlantis can also act as a conventional non-rising platform.

Going deeper

Design choice: a non-rising platform lets subjects use non-spatial strategies (for example circling at a fixed distance from the wall), which can make falling latencies look like spatial learning. A platform that sits well below the surface and rises only when the subject reaches or dwells at the location ensures spatial learning is needed. Using both can show preferred strategy and capability.

Clean the platform regularly with a soft brush, taking particular care with the magnets and electromagnets; you can take it apart by loosening the grub screws that hold the rods in the top and base. The control box holds a 9 V PP3 battery expected to last hundreds of trials; replace it before it fails to avoid disruption. Remove the Torx screws on the top with the supplied screwdriver, change the battery and refit the top by tightening each screw a little at a time.

Going deeper

This applies to the current control-box model. Older Atlantis models with a control tower and LiPo battery are charged instead: switch the tower to charging, connect the black balance cable and the black and red banana cables (black to black, red to red), select 'LiPo BALANCE 4.0A 14.8V (4S)' on the charger, hold Start/Enter until 'R:4SER S:4SER CONFRM' appears, then press Start/Enter. A bleep and 'Full' mean it is done; return the switch to the middle.

With the HVS Image Atlantis platform, the target diameter box sets the size of the target area the subject must reach, or dwell in, to trigger the platform to rise. It can be equal to, larger or smaller than the submerged platform, depending on how precisely you want the subject to locate it.

Going deeper

Rising is linked to the 'Auto-end on platform' setting in Trial Setup ('Yes', 'No', or 'Delay in Secs' for a dwell time) and to the calibrated platform number used for the trial. Choose 'No' to raise it manually with 'END'. Do not connect the platform to mains power; use only the control unit.