UCLA Miniscopes by Open Ephys

Flexible and affordable single photon calcium imaging

The UCLA Miniscope V4 is a lightweight, open-source fluorescence microscope designed for high-resolution fluorescent imaging in freely behaving animals.

Key Features

• 2.6 grams and 22 mm tall

• Field of view: 1 mm x 1 mm diameter

• Working distance: 675 ± 250 μm

• Electronic focal adjustment: ± 200 μm

• All high resolution achromatic optics

• Absolute head orientation sensor

• Requires ~1/5th the excitation power of previous systems

• Image cortical windows or deep brain regions with GRIN lenses

Connectivity

• Connects with the Miniscope DAQ for USB 3.0 data acquisition

• Uses a single coaxial cable (~ 1.1 mm in diameter) for power, communication, and data transmission

• Provides hardware sync and trigger options for precise timing and integration with other experimental hardware

• Stand alone software or integration with Bonsai visual programming language for flexible experiment design

In vivo calcium imaging for naturalistic experiments during ongoing behavior

The Miniscope is a head-mounted fluorescence microscope designed for one-photon in vivo calcium imaging in freely behaving animals. It enables the acquisition and real-time visualization of fluorescent indicators, such as generically encoded calcium indicators like GCaMP in behaving animals. It has a  1 mm diameter field of view which allows researchers to monitor activity across hundreds of neurons simultaneously in shallow (through cortical windows) or deep brain regions (by implanting a relay GRIN lens) without restraining the animal, and track the same cells across weeks. This makes it a powerful tool for studying the neural basis of behavior in naturalistic settings.

Acquire brain images and absolute head orientation data

The Miniscope uses a single, lightweight coaxial cable for power, control, and data transmission, which reduces tether weight compared to alternatives and greatly improves animal mobility. In its standard configuration, it uses a blue (470 nm) LED to excite GCaMP and a green-pass (500-550 nm) filter to image emitted fluorescence on a 0.48 MP CMOS sensor.

In addition to fluorescent imaging, the scope features a 9-axis inertial measurement unit (IMU), which provides high-resolution, real-time absolute orientation measurements (yaw, pitch, and roll) so that researchers can acquire functional imaging and head orientation data simultaneously. Head orientation data can both provide behavioral insights and is used to drive our torque-free coaxial commutator for freely-moving animals.

Tangle-free recording for long recording sessions

The Open Ephys Coaxial Commutator provides a tangle-free connection between the Miniscope DAQ and the Miniscope mounted on a freely-moving animal. This design is fundamentally different from others on the market. Instead of using a torque measurement to drive commutator motion, the commutator responds to the real-time head orientation data provided by the Miniscope’s integrated IMU. By using an IMU to sense the absolute orientation of the Miniscope, the active commutator rotates the tether accordingly without torque transmission through the tether. This enables recordings for extremely long durations without having to stop experiments due to tether twisting or animal fatigue.

Data acquisition and synchronization with the Miniscope DAQ

The Miniscope DAQ (data acquisition board) serves as the interface between a Miniscope and a computer. The DAQ connects to the computer through a high-speed USB 3.0, ensuring reliable and easy-to-use data transfer. Our redesigned  DAQ supports enhanced sync and trigger capabilities for hardware triggering, synchronization, and control. This allows frame-resolution synchronization with external devices such as behavioral cameras and external triggering to control recording sessions or LED activation. 

Miniscopes are also compatible with our multimodal ONIX acquisition system. This flexible acquisition ecosystem allows Miniscopes to be used in concert with other recording technologies simultaneously, such as neuropixels probes, passive silicon probes, or tetrode arrays. Click here for more information.

Easy habituation and stable Miniscope mounting

The Miniscope system relies on a machined aluminum base plate that serves as a robust, lightweight mounting interface for attaching the Miniscope to the animal's skull. The cone-tip set screw on the base plate secures onto a specific point on the Miniscope’s aluminum sleeve to ensure precise alignment and stability across imaging sessions while enabling easy attachment and detachment of the Miniscope between experiments. 

We also provide a micromachined replica that matches the weight and dimensions of the real device, called a “dummy scope”. This low-cost device is useful for habituation prior to experiments and for practicing miniscope mounting. The dummy scope can be used to  reduce stress during recordings, promoting natural behavior and consistent data collection during the actual imaging sessions.

Free, open-source acquisition software options

There are multiple software options for acquiring data for the Miniscope. The Miniscope GUI is produced by the Miniscope Team and provides a simple application for acquiring, controlling, and visualizing Miniscope data. The system is compatible with existing and future Miniscope Team software developments.

In addition, Open Ephys has developed the OpenEphys.Miniscope package for Bonsai, an open-source visual programming language which is ideal to control behavioral experiments with multiple hardware, such as cameras and behavioral devices. This package can be used for simple acquisition, control, and visualization miniscope data with seamless integration with the  torque free commutator. Since it’s a Bonsai Package, it can also be used in concert with hundreds of other pieces of supported hardware to perform complex closed-loop actuation of the Miniscope, online data processing, orchestrate complex behavioral tasks, and to build your own experimental GUIs.