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Neurologger with 3D Indoor Animal Tracking

Records neuronal brain activity and indoor positional data

Neurologger with 3D tracking can be used for position measurement with a sub-centimeter accuracy of terrestrial and avian species in the laboratory. It can be attached to a collar, to a backpack, or to an animal head.

The position measurement is based on the detection by the Neurologger of a planar infrared (IR) laser beam moving through the experimental environment with constant angular speed. The precise time of this detection serves as a measurement of the angular coordinate.

A short animation on the right shows 3D track of common marmoset (Callithrix jacchus) and its head orientation

Head orientation was obtained from on-board 3D accelerometer, 3D magnetometer and 3D gyroscope.
Vocalizations were recorded by on-board microphone.

 

3D tracking system

 

 

Simultaneous tracking of multiple animals is possible. A typical application is investigation of social interactions.In addition to optical tracking capabilities Neurologger 3 has an inertial tracking subsystem. It consists of 3D accelerometer, 3D gyroscope and 3D magnetometer (magnetic compass). All these 9D motion sensors have 16-bit resolution and can be polled with frequencies up to ~700 Hz.

The inertial tracking subsystem complements the optical tracking providing relative animal position at a higher sampling rate. It also helps to reconstruct animal path in case of challenging conditions, when optical transmitters are temporarily occluded. If the logger is attached to the animal head, the inertial tracking subsystem provides precise, drift-free 3D head orientation. In conjunction with a high-accuracy 3D tracking, head orientation can give additional information about animal behavior that can be especially important for studying of social interactions.


Components of 3D tracking system


Neurologger 3 with IR receiver

 

 

Scanning rates

1 transmitter: 60 Hz
2 transmitters: 30 Hz
3 transmitters: 20 Hz
4 transmitters: 15 Hz

 

 

 

Weight with 50 mAh battery – 3.5 g
Weight with 50 mAh battery and 32-ch neuronal headstage – 4.4 g

 

Notably, all tracking sensors can gather information simultaneously with neuronal data (or EEG/LFPs) and animal vocalization.
For instance, 32 neuronal channels can be sampled with frequency 15.625 kHz, microphone – 125 kHz, 9D motion sensors – 625 Hz.

Low current consumption (6.5 mA) of Neurologger 3 in EEG mode (32 channels, 250 Hz) allows longitudinal (> 24 h) experiments with small animals (e.g. in sleep research).

 

3D optical tracking achieves sub-centimeter
accuracy 3.1 ± 2.7 mm (Mean ± SD)

Euclidian distance between
a point of one track and
spline-interpolated second track

   

An example of 28-channel 15.625 kHz record of brain surface local field potentials (LFPs)
in western jackdaw (Coloeus monedula) during head movements and a call

Electrophysiological signals were band-pass filtered (0.3-3.0 kHz) to reveal multiunit activity. Note detection of vocal premotor activity in a set of posterior electrodes shown in red (in a gray rectangle).

 

Auditory event-related potentials (ERPs) recorded in the same jackdaw

Responses to 120 presentations of a sequence of conspecific vocalizations were averaged and band-pass (1-30 Hz) filtered. Channels with detected vocal premotor activity are plotted in red. A gray rectangle marks 13-second sequence of played calls.

   

3D tracking Neurologger 3 at the head of
western jackdaw (Coloeus monedula)

2D optical transmitter, IR emitter and video camera for observation mounted behind protective organic glass in the aviary


2017 Alexei Vyssotski