Floating BehaviouralPlatform archive

Experimental system

System architecture

A head-fixed behavioural platform designed to preserve body-driven orienting while retaining stable access for in vivo neural recording.

Scientific motivation

Why study orienting?

  • Orienting converts sensory locations into coordinated eye, head and body movements
  • The superior colliculus integrates multisensory information and contributes to target selection
  • Neuropixels can sample neural activity across superior-colliculus layers
  • Two-photon imaging can follow genetically defined cell populations during behaviour

The experimental trade-off

Head-fixed preparations

  • stable neural access
  • controlled trials
  • high trial counts
  • restricted whole-body behaviour

Freely moving preparations

  • natural movement
  • ethological behaviour
  • harder neural access
  • lower experimental control

The floating platform aims to combine stable head fixation with body-driven rotational orienting.

Behavioural platform

Low-friction orienting under stable neural access

The floating arena lets the animal's body drive rotational movement while stationary equipment retains access for acute Neuropixels recordings and two-photon imaging.

  1. 1
    Cue

    A selected reward port presents light or sound.

  2. 2
    Orient

    The mouse rotates the floating arena towards the target.

  3. 3
    Detect

    The light gate timestamps snout entry.

  4. 4
    Reward and align

    Liquid reward is delivered and the event is aligned with neural data.

  • Four distributed targets
  • Configurable visual and auditory cues
  • Continuous platform-position tracking
  • Stationary cameras and neural-recording equipment
  • Untethered communication across the floating boundary
Concept diagram of the floating behavioural platform A circular floating arena with four reward ports, a fixed head post, Korora on the platform and stationary acquisition equipment outside the floating boundary. 1 2 3 4 Korora
Schematic overview of the four-port floating-platform arrangement and the stationary acquisition boundary.

System components

Floating and stationary equipment

The architecture separates devices that rotate with the platform from the stationary equipment used for acquisition, timing alignment and behavioural control.

Floating platform

A lightweight circular arena supported by an air cushion. The mouse's body drives low-friction platform rotation while the head remains fixed.

Reward ports / Fairy controllers

Four modular target stations positioned around the arena.

  • RGB visual cue
  • speaker output
  • infrared light gate
  • liquid reward outlet
  • timed valve actuation
  • local STM32 control
  • local event timestamping

Korora - mobile platform hub

Located on the floating platform.

  • communicates with the behavioural control software
  • issues commands to reward-port controllers
  • collects buffered events
  • manages device timing relationships
  • discovers and addresses connected Fairy controllers

Galapagos - stationary timing interface

Located beside the stationary DAQ, Galapagos provides the timing interface for physical TTL alignment.

  • receives scheduled timing events wirelessly
  • generates physical TTL outputs
  • provides alignment between behavioural events and stationary acquisition equipment

Behavioural control software

  • configures behavioural protocols
  • selects targets, cues and reward timing
  • receives event records
  • stores events on the shared experimental timeline

Position tracking and acquisition

  • Camera and markers recover platform orientation
  • Cameras, DAQ, imaging and electrophysiology equipment remain stationary
  • TTL signals align behavioural events with external systems

Communication and timing

Untethered control with local event timing

BLE is used across the rotating boundary. Within the floating platform, UART over RS485 connects Korora to the distributed Fairy controllers.

Download original file Diagram separating the floating-platform communication network from stationary behavioural-control and DAQ equipment.
Physical communication architecture Korora and the reward-port controllers move with the floating platform. BLE connects the untethered platform to behavioural software and the stationary Galapagos timing interface, while UART over RS485 connects devices within the platform. Open media record
Download original file Diagram showing a reward-port event timestamped locally, transported through Korora and translated onto a shared timeline.
From local detection to a common timeline A reward-port event is timestamped locally, transported to Korora and translated onto the shared experimental timeline using the current affine clock model. Open media record

Hardware synchronisation pulses and BLE anchor events provide timestamp pairs. Rolling 16-point affine models correct clock offset and oscillator-rate differences between independently clocked devices.

Transport delay changes record arrival time, not the local timestamp assigned to the physical event.

Related media

BLE RSSI measurements over time grouped by logical node.

Plot

BLE signal strength by node

Tracks wireless signal strength and helps distinguish radio degradation from software congestion.

  • ble
  • rssi
  • connectivity

Reward-port design

Local cue, detection and reward control

Each reward port independently presents cues, timestamps snout entry and delivers a timed liquid reward.

Download original file Front view of a reward port showing cue, speaker, light gate and liquid-delivery outlet.
Reward-port front assembly Front view showing the visual cue, speaker, light gate and reward outlet used for cue presentation, snout-entry detection and liquid delivery. Open media record
Download original file Rear view of a reward-port controller with STM32 control electronics and connectors.
Reward-port control electronics Rear view showing the custom STM32 control board, audio circuitry, valve driver and platform power and communication connectors. Open media record
Full reward-port 3D model Interactive GLB model of the full reward-port assembly used for visual inspection of the prototype geometry. Reward-port PCB 3D model Interactive GLB model of the reward-port control PCB used to inspect board layout and connector placement.

Related media

Interactive 3D model of the complete Fairy reward-port assembly.

3D model

Full reward-port 3D model

Interactive GLB model of the full reward-port assembly used for visual inspection of the prototype geometry.

  • system
  • reward-port
  • fairy
  • model
  • hardware
Interactive 3D model of the Fairy reward-port control PCB.

3D model

Reward-port PCB 3D model

Interactive GLB model of the reward-port control PCB used to inspect board layout and connector placement.

  • system
  • reward-port
  • fairy
  • model
  • pcb
  • electronics

Integrated prototype

Electronics bench prototype

The current prototype integrates the main electronics and software paths before full arena assembly.

Bench prototype containing the Korora mobile hub, Fairy reward-port controllers, Galapagos timing interface and host control software.

Demonstrated capabilities

  • visual and auditory cue generation
  • snout-entry detection
  • timed valve actuation
  • distributed event collection
  • multi-node communication
  • cross-device clock modelling
  • scheduled TTL generation
Download original file Bench prototype with the Korora hub, Fairy reward-port controllers, Galapagos timing interface and host control software.
Integrated breadboard prototype

Audio demonstrations

Bench demonstrations of programmable audio playback through a Fairy reward-port controller.

Download original video
Programmable speaker-output demonstration 1
Download original video
Programmable speaker-output demonstration 2

Previous system

Previous platform compared with the redesign

The redesign retains the original behavioural concept while adding configurable stimuli, distributed control and traceable event timing.

Comparison between the previous behavioural platform and the redesigned distributed system.
Previous platform Redesigned platform
Arduino Nano controller distributed STM32 reward-port controllers
four I2C GPIO expanders configurable RGB output
fixed LED output configurable tones and band-limited noise
fixed-frequency speaker output generated using a 555 timer local valve actuation
central valve control local light-gate timestamps
central light-break detection BLE across the floating boundary
limited timing observability UART over RS485 within the platform
external TTL alignment
automatic controller discovery and addressing
sequence and health reporting

Current Status

Implemented

  • functional reward-port prototype
  • wireless multi-node communication
  • cross-device clock alignment
  • externally validated TTL timing

Next steps

  • manufacture custom circuit boards
  • integrate four reward ports
  • calibrate delivered reward volume
  • validate during in vivo experiments
  • continue Python and Bonsai integration