New platform enables multimodal recording in the wild

A new platform records neuronal activity and multiple behavioral measures, and includes optogenetic stimulation, enabling researchers to study the neuronal underpinnings of small animals’ behavior in natural environments. Researchers describe the platform in a paper published last month in Nature Methods.

Previous efforts to record and manipulate neuronal activity in freely moving animals typically used tethers, which interfere with natural movement, especially in social settings involving multiple animals. Wireless devices exist, but these are usually heavy, which can also affect behavior, and they have limited battery life.

“Our dream was to bring neuroscientific studies closer to the natural behaviors animals express in the wild,” says study investigator Antonio Fernandez-Ruiz, associate professor of neurobiology and behavior at Cornell University.

The device, called WILD (Wireless, Interactive, Lightweight Datalogger), combines recording electrodes with multiple behavioral sensors (a head-mounted camera, a microphone and a motion-tracking unit) and an optogenetic stimulation module. Rather than transmitting neuronal data, the device includes onboard signal processing and a microSD card for storage. It also incorporates a microcontroller unit and Bluetooth wireless communication of control and synchronization signals.

“What makes this impressive is the level of integration into a platform that can do multimodal recording, onboard processing and neuronal manipulation in a package that supports freely moving animals,” says Daniel Aharoni, associate professor-in-residence of neurology at the University of California, Los Angeles, who was not involved in the work. “Bringing these capabilities together makes experiments in complex environments and social settings much more practical.”

The platform weighs 4.7 grams, including a 1.65 gram battery and casing. A 2.5 gram battery would allow about three hours of continuous neuronal recording, using 64 channels and sampling at 20 kilohertz, but the device is highly configurable. “You can enable or disable any component or run it at a reduced sampling rate for longer, so it’s easily tailored to different experiments,” says study investigator Zifang Zhao, a research associate in Fernandez-Ruiz’s lab who led the engineering.

“The idea was to enable a field of research at the intersection between neuroscience and ecology,” says study investigator Azahara Oliva, assistant professor of neurobiology and behavior at Cornell. Previously, researchers could record brain activity while animals performed laboratory tasks, or behavior over longer time frames in nature. “Here we can look at both,” Oliva says. “We can see what animals do in the natural environment and correlate it with changes in light, temperature or the presence of predators.” This opens up experiments investigating everything from the effect of seasons on the brain to the long-term impacts of psychedelic drugs, Fernandez-Ruiz says.