A framework for relating neural activity to freely moving behavior

Abstract

Abstract-Two research communities, motor systems neuroscience and motor prosthetics, examine the relationship between neural activity in the motor cortex and movement. The former community aims to understand how the brain controls and generates movement; the latter community focuses on how to decode neural activity as control signals for a prosthetic cursor or limb. Both have made progress toward understanding the relationship between neural activity in the motor cortex and behavior. However, these findings are tested using animal models in an environment that constrains behavior to simple, limited movements. These experiments show that, in constrained settings, simple reaching motions can be decoded from small populations of spiking neurons. It is unclear whether these findings hold for more complex, full-body behaviors in unconstrained settings. Here we present the results of freelymoving behavioral experiments from a monkey with simultaneous intracortical recording. We investigated neural firing rates while the monkey performed various tasks such as walking on a treadmill, reaching for food, and sitting idly. We show that even in such an unconstrained and varied context, neural firing rates are well tuned to behavior, supporting findings of basic neuroscience. Further, we demonstrate that the various behavioral tasks can be reliably classified with over 95% accuracy, illustrating the viability of decoding techniques despite significant variation and environmental distractions associated with unconstrained behavior. Such encouraging results hint at potential utility of the freely-moving experimental paradigm.

A freely-moving monkey treadmill model

“…[34]), as well as an important step towards designing even more complex in-cage and in-the-wild monkey models, which require even more complex and robust neural recording and behavioral tracking systems (see Discussion). We have previously reported, preliminarily, that neural activity encodes walking and reaching [35,36]. Here, we substantially extend these previous preliminary reports by demonstrating results in two rhesus monkeys (which is critical for knowing if the scientific results generalize across monkeys), analyze how neural activity covaries with changes in walking speeds, and analyze population level activity so as to report the first comprehensive study of the treadmill monkey model and associated scientific results.…”

A wireless transmission neural interface system for unconstrained non-human primates

“…Several wireless recording systems have been developed for a variety of freely moving animal models such as rodents (Rizk et al, 2007, Szuts et al, 2011, Lee et al, 2013), sheep (Rizk et al, 2009), and non-human primate (Borton et al, 2013, Miranda et al, 2010, Ryou and Wilson, 2004, Schwarz et al, 2014, Foster et al, 2014, Foster et al, 2012, Chestek et al, 2011, Chestek et al, 2009) using commercial off the shelf electronics. However, there are still limitations in the development of the wireless technology in terms of trade-offs between power consumption, performance in data transmission, quality of signals, and device size.…”