TY - JOUR

T1 - Temporal dynamics of neuronal activation by Channelrhodopsin-2 and TRPA1 determine behavioral output in Drosophila larvae

AU - Pulver, Stefan R

AU - Pashkovski, Stanislav L

AU - Hornstein, Nicholas J

AU - Garrity, Paul A

AU - Griffith, Leslie C

PY - 2009/6

Y1 - 2009/6

N2 - In recent years, a number of tools have become available for remotely activating neural circuits in Drosophila. Despite widespread and growing use, very little work has been done to characterize exactly how these tools affect activity in identified fly neurons. Using the GAL4-UAS system, we expressed blue light-gated Channelrhodopsin-2 (ChR2) and a mutated form of ChR2 (H134R-ChR2) in motor and sensory neurons of the Drosophila third-instar locomotor circuit. Neurons expressing H134R-ChR2 show enhanced responses to blue light pulses and less spike frequency adaptation than neurons expressing ChR2. Although H134R-ChR2 was more effective at manipulating behavior than ChR2, the behavioral consequences of firing rate adaptation were different in sensory and motor neurons. For comparison, we examined the effects of ectopic expression of the warmth-activated cation channel Drosophila TRPA1 (dTRPA1). When dTRPA1 was expressed in larval motor neurons, heat ramps from 21 to 27 degrees C evoked tonic spiking at approximately 25 degrees C that showed little adaptation over many minutes. dTRPA1 activation had stronger and longer-lasting effects on behavior than ChR2 variants. These results suggest that dTRPA1 may be particularly useful for researchers interested in activating fly neural circuits over long time scales. Overall, this work suggests that understanding the cellular effects of these genetic tools and their temporal dynamics is important for the design and interpretation of behavioral experiments.

AB - In recent years, a number of tools have become available for remotely activating neural circuits in Drosophila. Despite widespread and growing use, very little work has been done to characterize exactly how these tools affect activity in identified fly neurons. Using the GAL4-UAS system, we expressed blue light-gated Channelrhodopsin-2 (ChR2) and a mutated form of ChR2 (H134R-ChR2) in motor and sensory neurons of the Drosophila third-instar locomotor circuit. Neurons expressing H134R-ChR2 show enhanced responses to blue light pulses and less spike frequency adaptation than neurons expressing ChR2. Although H134R-ChR2 was more effective at manipulating behavior than ChR2, the behavioral consequences of firing rate adaptation were different in sensory and motor neurons. For comparison, we examined the effects of ectopic expression of the warmth-activated cation channel Drosophila TRPA1 (dTRPA1). When dTRPA1 was expressed in larval motor neurons, heat ramps from 21 to 27 degrees C evoked tonic spiking at approximately 25 degrees C that showed little adaptation over many minutes. dTRPA1 activation had stronger and longer-lasting effects on behavior than ChR2 variants. These results suggest that dTRPA1 may be particularly useful for researchers interested in activating fly neural circuits over long time scales. Overall, this work suggests that understanding the cellular effects of these genetic tools and their temporal dynamics is important for the design and interpretation of behavioral experiments.

KW - Action Potentials

KW - Analysis of Variance

KW - Animals

KW - Animals, Genetically Modified

KW - Arginine

KW - Behavior, Animal

KW - Biophysics

KW - Color

KW - Drosophila

KW - Drosophila Proteins

KW - Electric Stimulation

KW - Female

KW - Green Fluorescent Proteins

KW - Histidine

KW - Larva

KW - Light

KW - Locomotion

KW - Mutation

KW - Neuromuscular Junction

KW - Neurons

KW - Nonlinear Dynamics

KW - Patch-Clamp Techniques

KW - Rhodopsin

KW - TRPC Cation Channels

KW - Temperature

KW - Time Factors

U2 - 10.1152/jn.00071.2009

DO - 10.1152/jn.00071.2009

M3 - Article

C2 - 19339465

VL - 101

SP - 3075

EP - 3088

JO - Journal of Neurophysiology

JF - Journal of Neurophysiology

SN - 0022-3077

IS - 6

ER -