Molecular Biology Faculty

Mala Murthy

This email address is being protected from spambots. You need JavaScript enabled to view it.	Murthy Research Lab
(609) 258-9820	Moffet Lab, 328
	Lab (609) 258-2156
Faculty Assistant	Nicolette chavez
This email address is being protected from spambots. You need JavaScript enabled to view it.	(609) 258-5515

Research Focus

OLFACTORY AND AUDITORY PERCEPTION IN DROSOPHILA

How does the brain process sensory stimuli and use this information to direct appropriate behaviors? To address this question, our lab studies the neural codes (patterns of electrical activity) underlying olfactory and auditory perception in the fruit fly, Drosophila.

The goal of our research is to determine how odors and sounds are encoded within the fly brain and to understand how these representations constitute a percept of the environment -- a percept the fly uses to make important behavioral choices (eg, to navigate towards a sweet-smelling odor, or to mate with a fly singing a conspecific courtship song). Drosophila, with its relatively simple nervous system, well-studied behaviors, amenability for in vivo electrophysiology, and large genetic and molecular toolkit offers an ideal system in which to examine questions about sensory coding.

We typically study neurons that are several synapses downstream from the sensory periphery, in order to examine 'higher-level' aspects of sensory processing. We are also particularly interested in how nervous systems cope with variability – that is, how reproducible behaviors are elicited given variations in the sensory stimulus and in neural representations of the stimulus (both within and between animals).

Olfactory Perception

In the mushroom body, the fly's olfactory learning and memory center, we have discovered that each fly possesses a complement of Kenyon cells (KCs; the principal neurons of the mushroom body) whose odor tuning differs from individual to individual. We speculate that in a system responsible for associative learning, variability in the connection matrix used to generate and learn the representations of significant stimuli may be useful to the species at large. This study defined a method for measuring the across-animal variability of individual neurons within a large population, using a combination of genetic labeling, single-cell electrophysiology, and computational models. Using similar methods, we are following up these results by recording from the postsynaptic targets of the KCs, the mushroom body extrinsic neurons (MBEs). Among this smaller population we are investigating how olfactory memories (positive and negative associations) are reliably formed in this structure, given some degree of variability present in the system, and the overall logic of olfactory coding within the mushroom body (ie, which subsets of KCs and MBEs participate in particular representations).

Auditory Perception

Acoustic communication in flies is based on the production and perception of courtship song – songs are produced by males via wing vibration and are unique to each species (there are ~2000 Drosophila species). Females are faced with the task of recognizing song, based on its species-specific parameters, and responding with an appropriate behavioral program. What features of song do females utilize when deciding to mate? How is song feature detection accomplished (at the level of single neurons and patterns of neural activity)? And, what effect does past experience have on song perception? We utilize a combination of genetic, behavioral, imaging, in vivo electrophysiological, and computational methods to address these questions. The ability to quantify the natural acoustic environment for Drosophila (in terms of temporal pattern, frequency, and amplitude) and the fact that auditory behaviors (courtship and mating) are very robust in flies facilitates our quantitative analysis of both behavior and neural recordings. Inspired by the recent sequencing of twelve Drosophila genomes and the potential for the development of genetic tools across species, we are taking a comparative approach to understanding the neural coding of courtship song by presenting auditory stimuli from and performing electrophysiological recordings in several of these species.