The Journal of Neuroscience, September 12, 2007, 27(37):10047-10059; doi:10.1523/JNEUROSCI.1515-07.2007
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Behavioral/Systems/Cognitive
Relationship between the Phases of Sensory and Motor Activity during a Looming-Evoked Multistage Escape Behavior
Haleh Fotowat1 and
Fabrizio Gabbiani1,2
1Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, and 2Computational and Applied Mathematics, Rice University, Houston, Texas 77005
Correspondence should be addressed to Fabrizio Gabbiani, Department of Neuroscience, Room S557, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030. Email: gabbiani{at}bcm.edu
The firing patterns of visual neurons tracking approaching objects need to be translated into appropriate motor activation sequences to generate escape behaviors. Locusts possess an identified neuron highly sensitive to approaching objects (looming stimuli), thought to play an important role in collision avoidance through its motor projections. To study how the activity of this neuron relates to escape behaviors, we monitored jumps evoked by looming stimuli in freely behaving animals. By comparing electrophysiological and high-speed video recordings, we found that the initial preparatory phase of jumps occurs on average during the rising phase of the firing rate of the looming-sensitive neuron. The coactivation period of leg flexors and extensors, which is used to store the energy required for the jump, coincides with the timing of the peak firing rate of the neuron. The final preparatory phase occurs after the peak and takeoff happens when the firing rate of the looming-sensitive neuron has decayed to <10% of its peak. Both the initial and the final preparatory phases and takeoff are triggered when the approaching object crosses successive threshold angular sizes on the animal's retina. Our results therefore suggest that distinct phases of the firing patterns of individual sensory neurons may actively contribute to distinct phases of complex, multistage motor behaviors.
Key words: locust; DCMD; jump escapes; sensorimotor transformation; high speed video; electrophysiology
Received April 4, 2007;
revised July 16, 2007;
accepted July 17, 2007.
Correspondence should be addressed to Fabrizio Gabbiani, Department of Neuroscience, Room S557, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030. Email: gabbiani{at}bcm.edu