Designing and Implementing Nervous System Simulations on LEGO Robots

Summary

An approach to neural network modeling on the LEGO Mindstorms robotics platform is presented. The method provides a simulation tool for invertebrate neuroscience research in both the research lab and the classroom. This technique enables the investigation of biomimetic robot control principles.

Abstract

We present a method to use the commercially available LEGO Mindstorms NXT robotics platform to test systems level neuroscience hypotheses. The first step of the method is to develop a nervous system simulation of specific reflexive behaviors of an appropriate model organism; here we use the American Lobster. Exteroceptive reflexes mediated by decussating (crossing) neural connections can explain an animal's taxis towards or away from a stimulus as described by Braitenberg and are particularly well suited for investigation using the NXT platform.¹ The nervous system simulation is programmed using LabVIEW software on the LEGO Mindstorms platform. Once the nervous system is tuned properly, behavioral experiments are run on the robot and on the animal under identical environmental conditions. By controlling the sensory milieu experienced by the specimens, differences in behavioral outputs can be observed. These differences may point to specific deficiencies in the nervous system model and serve to inform the iteration of the model for the particular behavior under study. This method allows for the experimental manipulation of electronic nervous systems and serves as a way to explore neuroscience hypotheses specifically regarding the neurophysiological basis of simple innate reflexive behaviors. The LEGO Mindstorms NXT kit provides an affordable and efficient platform on which to test preliminary biomimetic robot control schemes. The approach is also well suited for the high school classroom to serve as the foundation for a hands-on inquiry-based biorobotics curriculum.

Introduction

Neurophysiological investigations over the past 100 years have broadened tremendously our knowledge of nervous system structure and function. However, the majority of nervous system research to date has relied on the use of isolated preparations or restrained subjects. While there have been many successful efforts to record neural activity from freely behaving animals^2-5, the biorobotic approach provides a valuable tool to allow for nervous system manipulation in order to test systems level neuroscience hypotheses⁶. Simulated nervous systems operating on robots can be experimentally manipulated and allow for the extension of software modeling to ....

Protocol

1. Building the Robot Model

1. Choose a model organism to study that is well represented in the neuroethological literature. Invertebrates generally make good candidates because their relatively simple nervous systems have been well studied and are primarily comprised of innate reflexes. We will demonstrate this approach using the American Lobster, Homarus americanus.
2. Select well-studied reflexive behaviors for modeling purposes. We have chosen the lobster's responses to antennal bend and to claw bump detection as the animal reflexively responds to bending of antennae to elicit rheotaxis (orientation to water flow) while claw contacts ....

Results

Inputs from a lobster's claws into its nervous system mediate obstacle negotiation in a novel environment. Figure 1 shows a screenshot of the video used to analyze the behavior of a LEGO robot (Figure 1A) and a lobster (Figure 1B) in the test arena. The test arena was unmodified between animal and robot tests except that the water was emptied from the tank for the robot trials.

Video tracking results are displayed in Figure 2........

Discussion

When initiating biorobotic nervous system simulation experiments, there are a few important guidelines to follow. Choosing the right model organism is critical: pick an organism that is easy to obtain and maintain. Invertebrates are ideal because they do not usually require institutional approval for experimentation and their husbandry needs are often less demanding than those of vertebrates. From a scientific perspective, it is beneficial to choose an animal that has an established neuroethological literature record fro.......