Ecology and Evolution of Communication
Communication systems evolved in response to a myriad of social and ecological factors. The aim of this line of research is to elucidate the environmental, acoustic and social influences on vocal communication in wild marmosets. These field studies are conducted on populations of marmosets in the forests of Northeastern Brazil. Our initial studies sought to examine the impact of habitat acoustics on the evolution of marmoset vocalizations. Currently we are developing wearable collars capable of recording each animal’s vocalizations, spatial position and other biometric data in order to examine the ongoing vocal interactions that occur within and between groups of marmosets. Implementing this technology will allow us to eavesdrop on the natural occurring conversations of these wild primates.
Neurobiology of Natural Behavior
The majority of what is known about the neural basis of behavior in nonhuman primates comes from studies in which subjects performed a conditioned behavioral task. Relatively remains known about whether similar neural processes occur when individuals behave naturally. This contrast is particularly important in social and communicative interactions, which are difficult to recreate in restrained animals. The aim of these experiments is to examine the neural mechanisms underlying natural behavior in primate neocortex. Our experiments focus on naturally occurring vocal interactions in marmosets and comprise studies of both behavior and neurobiology. We perform single neuron recordings in marmoset frontal and auditory cortex while freely-moving subjects engage in aspects of their natural vocal behavior. In order to control these interactions in an experimental context, we developed simulated communication network comprising ‘Virtual Monkeys’ whose behavior can be parametrically manipulated. Our approach allows us the unique opportunity to directly engage marmosets in communication exchanges, experimentally manipulate parameters of these interactions and record the underlying neural activity.
Neural Circuitry Underlying Audition
The neural circuitry underlying many aspects of auditory perception and cognition in primates is not well known. Experiments in this line of research aims to address this issue by employing a range of complementary neuroscientific techniques to examine the neural basis of perceptual behaviors in marmosets. We recently developed an awake fMRI preparation for marmosets in order to identify the regions of auditory cortex involved in a perceptual task, as well as Optogenetic methods for manipulating these cortical substrates in order to test their functional contributions. Current work to develop a 2-photon calcium imaging preparation for awake-behaving marmosets will allow us to examine the population dynamics of auditory cortex during perceptual behaviors. We are currently employing these methods in a series of studies examining Frequency-Modulation, a key aspect of sound perception for many complex signals, including speech and other vocal signals.