Design and construction of a low-cost nose poke system for rodents

Open-source raspberry Pi-based operant box for translational behavioral testing in rodents

BACKGROUND

Rodents have been used for decades to probe neural circuits involved in behavior. Increasingly, attempts have been developed to standardize training paradigms across labs; and to use visual/auditory paradigms that can be also tested in humans. Commercially available systems are expensive and thus do not scale easily, and are not optimized for electrophysiology.

NEW METHOD

Using the rich open-source technology built around Raspberry Pi, we were able to develop an inexpensive (<$1000) visual-screen based operant chamber with electrophysiological and optogenetic compatibility. The chamber is operated within MATLAB/Simulink, a commonly used scientific programming language allowing for rapid customization.

RESULTS

Here, we describe and provide all relevant details needed to develop and produce these chambers, and show examples of behavior and electrophysiology data collected using these chambers. We also include all of the tools needed to allow readers to build and develop their own boxes (CAD models for 3D printing and laser-cutting; PCB-board design; all bill of materials for required parts and supplies, and some examples of Simulink models to operate the boxes).

COMPARISON WITH EXISTING METHODS

The new boxes are far more cost-effective than commercially available environments and allow for the combination of automated behavioral testing with electrophysiological read-outs with high temporal precision.

CONCLUSION

These open-source boxes can be used for labs interested in developing high-throughput visual/auditory behavioral assays for ∼ 10th the cost of commercial systems.

Two open source designs for a low-cost operant chamber using Raspberry Pi™

After almost a century of use and development, operant chambers remain a significant financial investment for scientists. Small powerful single-board computers such as the Raspberry Pi™ offer researchers a low-cost alternative to expensive operant chambers. In this paper, we describe two new operant chambers, one using nose-poke ports as operanda and another using a touchscreen. To validate the chamber designs, rats learned to perform both visual discrimination and delayed alternation tasks in each chamber. Designs and codes are open source and serve as a starting point for researchers to develop behavioral experiments or educational demonstrations.

A low-cost touchscreen operant chamber using a Raspberry Pi™

The development of a touchscreen platform for rodent testing has allowed new methods for cognitive testing that have been back-translated from clinical assessment tools to preclinical animal models. This platform for cognitive assessment in animals is comparable to human neuropsychological tests such as those employed by the Cambridge Neuropsychological Test Automated Battery, and thus has several advantages compared to the standard maze apparatuses typically employed in rodent behavioral testing, such as the Morris water maze. These include improved translation of preclinical models, as well as high throughput and the automation of animal testing. However, these systems are relatively expensive, which can impede progress for researchers with limited resources. Here we describe a low-cost touchscreen operant chamber based on the single-board computer, Raspberry Pi^TM, which is capable of performing tasks similar to those supported by current state-of-the-art systems. This system provides an affordable alternative for cognitive testing in a touchscreen operant paradigm for researchers with limited funding.

Open Source Tools for Temporally Controlled Rodent Behavior Suitable for Electrophysiology and Optogenetic Manipulations

Understanding how the brain controls behavior requires observing and manipulating neural activity in awake behaving animals. Neuronal firing is timed at millisecond precision. Therefore, to decipher temporal coding, it is necessary to monitor and control animal behavior at the same level of temporal accuracy. However, it is technically challenging to deliver sensory stimuli and reinforcers as well as to read the behavioral responses they elicit with millisecond precision. Presently available commercial systems often excel in specific aspects of behavior control, but they do not provide a customizable environment allowing flexible experimental design while maintaining high standards for temporal control necessary for interpreting neuronal activity. Moreover, delay measurements of stimulus and reinforcement delivery are largely unavailable. We combined microcontroller-based behavior control with a sound delivery system for playing complex acoustic stimuli, fast solenoid valves for precisely timed reinforcement delivery and a custom-built sound attenuated chamber using high-end industrial insulation materials. Together this setup provides a physical environment to train head-fixed animals, enables calibrated sound stimuli and precisely timed fluid and air puff presentation as reinforcers. We provide latency measurements for stimulus and reinforcement delivery and an algorithm to perform such measurements on other behavior control systems. Combined with electrophysiology and optogenetic manipulations, the millisecond timing accuracy will help interpret temporally precise neural signals and behavioral changes. Additionally, since software and hardware provided here can be readily customized to achieve a large variety of paradigms, these solutions enable an unusually flexible design of rodent behavioral experiments.

Effects of 5-HT5A receptor blockade on amnesia or forgetting

Previously the effects (0.01-3.0 mg/kg) of post-training SB-699551 (a 5-HT_5A receptor antagonist) were reported in the associative learning task of autoshaping, showing that SB-699551 (0.1 mg/kg) decreased lever-press conditioned responses (CR) during short-term (STM; 1.5-h) or (3.0 mg/kg) long-term memory (LTM; 24-h); relative to the vehicle animals. Moreover, as pro-cognitive efficacy of SB-699551 was reported in the ketamine-model of schizophrenia. Hence, firstly aiming improving performance (conditioned response, CR), in this work autoshaping lever-press vs. nose-poke response was compared; secondly, new set of animals were randomly assigned to SB-699551 plus forgetting or amnesia protocols. Results show that the nose-poke operandum reduced inter-individual variance, increased CR and produced a progressive CR until 48-h. After one week of no training/testing sessions (i.e., interruption of 216 h), the forgetting was observed; i.e., the CR% of control-saline group significantly decreased. In contrast, SB-699551 at 0.3 and 3.0 mg/kg prevents forgetting. Additionally, as previously reported the non-competitive NMDA receptor antagonist dizocilpine (0.2 mg/kg) or the non-selective cholinergic antagonist scopolamine (0.3 mg/kg) decreased CR in STM. SB-699551 (0.3 mg/kg) alone also produced amnesia-like effect. Co-administration of SB-699551-dizocilpine or SB-699551-scopolamine reversed the SB-699551 induced-amnesic effects in LTM (24-h). Nose-poke seems to be a reliable operandum. The anti-amnesic and anti-forgetting mechanisms of amnesic SB-699551-dose remain unclear. The present findings are consistent with the notion that low doses of 5-HT_5A receptor antagonists might be useful for reversing memory deficits associated to forgetting and amnesia. Of course, further experiments are necessary.

ArControl: An Arduino-Based Comprehensive Behavioral Platform with Real-Time Performance

Studying animal behavior in the lab requires reliable delivering stimulations and monitoring responses. We constructed a comprehensive behavioral platform (ArControl: Arduino Control Platform) that was an affordable, easy-to-use, high-performance solution combined software and hardware components. The hardware component was consisted of an Arduino UNO board and a simple drive circuit. As for software, the ArControl provided a stand-alone and intuitive GUI (graphical user interface) application that did not require users to master scripts. The experiment data were automatically recorded with the built in DAQ (data acquisition) function. The ArControl also allowed the behavioral schedule to be entirely stored in and operated on the Arduino chip. This made the ArControl a genuine, real-time system with high temporal resolution (<1 ms). We tested the ArControl, based on strict performance measurements and two mice behavioral experiments. The results showed that the ArControl was an adaptive and reliable system suitable for behavioral research.

An open source device for operant licking in rats

We created an easy-to-use device for operant licking experiments and another device that records environmental variables. Both devices use the Raspberry Pi computer to obtain data from multiple input devices (e.g., radio frequency identification tag readers, touch and motion sensors, environmental sensors) and activate output devices (e.g., LED lights, syringe pumps) as needed. Data gathered from these devices are stored locally on the computer but can be automatically transferred to a remote server via a wireless network. We tested the operant device by training rats to obtain either sucrose or water under the control of a fixed ratio, a variable ratio, or a progressive ratio reinforcement schedule. The lick data demonstrated that the device has sufficient precision and time resolution to record the fast licking behavior of rats. Data from the environment monitoring device also showed reliable measurements. By providing the source code and 3D design under an open source license, we believe these examples will stimulate innovation in behavioral studies. The source code can be found at http://github.com/chen42/openbehavior.