A number of techniques are in use or being developed in the lab, including single-unit extracellular and intracellular recording, wireless multi-channel electrode recording, optogenetics, two-photon chronic imaging, transgenic lines...
(Sabyasachi and Wang, 2012) The ability to record well-isolated action potentials from individual neurons in naturally behaving animals is crucial for understanding neural mechanisms underlying natural behaviors. Traditional neurophysiology techniques, however, require the animal to be restrained which often restricts natural behavior. An example is the common marmoset (Callithrix jacchus), a highly vocal New World primate species, used in our laboratory to study the neural correlates of vocal production and sensory feedback. This paper describes an experimental setup capable of recording multiple single units from freely roaming and vocalizing small subjects using a novel neural telemetry system. This system is capable of simultaneously recording single units from different cortical sites within a radio frequency and acoustically controlled environment.
Figure 1. Wireless neural headstage and multi-electrode array. (A) Warp-16 (Neuralynx) sixteen channel multi-electrode array on the left and W16 (TBSI) sixteen channel wireless neural headstage shown on the right. (B) Approximate location of electrode array in the marmoset left hemisphere. (C) Wireless neural headstage and electrode array assembly is shown along with the protective chamber for use during free-roaming recordings. (D) Individual components of the protective cap for the headstage and multi-electrode array assembly.
(Remington et al., 2012)Here we describe an operant conditioning behavioral training method developed to allow controlled psychoacoustic measurements in marmosets. We demonstrate that marmosets can be trained to consistently perform a Go/No-Go auditory task in which a subject licks at a feeding tube when it detects a sound. Correct responses result in delivery of a food reward. Crucially, this operant conditioning task generates little body movement and is well suited for pairing behavior with single-unit electrophysiology. Successful implementation of an operant conditioning behavior opens the door to a wide range of new studies in the field of auditory neuroscience using the marmoset as a model system.
Figure 1. Marmoset chair and behavior setup. A. Marmoset chair with feeding tube, infrared lick detector, and optional head restraint mechanism for single-unit recording. The neck plate slides out to allow a marmoset to enter the chair from below. After securing neck plate, the feeding tube can be adjusted to create a comfortable reach for each monkey. B. Schematic of task setup. Sounds are played from free field speakers while marmosets lick to target sounds for a reward which is delivered by a syringe pump via a feeding tube. Lick responses are recorded when the infrared beam is broken by the animal’s face or tongue. Behavior apparatus are controlled by a personal computer and powered by a custom built power supply and electrical isolation module.