We also show that an integrate-and-fire computational model of the Mauthner cell reproduces fish responses to multisensory stimuli, making a direct link between behavioral data and its underlying neural mechanism.
Here we demonstrate that in goldfish auditory and visual stimuli can be integrated to enhance C-start probability and reduce response latency. The one-to-one relationship between a C-start and firing in the Mauthner cell offers a unique opportunity to study how multisensory integration in a single neuron impact on a fast escape behavior. Auditory C-starts are triggered by intense and brief auditory pips while visual C-start responses are typically evoked by fast expanding dark disks ( 14, 16, 21). The temporal structure of auditory or visual stimuli that consistently trigger C-starts differs ( 17, 20). Auditory salience depends on the amplitude of the sound wave while visual salience has been tied to stimulus dynamics and contrast ( 14, 16– 19). Both auditory and visual stimuli can activate the Mauthner cell with a probability and response latency that are function of the stimulus salience ( 11, 14, 15). Mauthner cells have two main dendrites: disynaptic auditory input arriving from the inner ear contacts de lateral dendrite of the Mauthner cell ( 9– 11) while polysynaptic visual input coming from the optic tectum contacts the ventral dendrite of the cell ( 12, 13). The C-start is initiated by a bilateral pair of reticulospinal neurons called Mauthner cells which determine the occurrence, latency and direction of the escape ( 8). Teleost fish can perform different evasive behaviors, the most explosive known as C-start fast escape. However, studies where behavioral correlates of multisensory integration can be directly tied to activity in an identified neuronal circuit are very rare and limited by the complexity and distribution of the neuronal networks involved. Depending on the perceived level of danger, animals might seek refuge, display freezing or alarm responses and when danger is extreme, fast escape behaviors ( 5– 7). After detecting a potential threat animals can perform a variety of protective behaviors. Multisensory integration becomes critically important for threat detection, when small reductions in sensory ambiguity can have a huge impact in the survival of the animal ( 4).
At the cellular level, integration performed by multisensory neurons is determined by synaptic convergence of sensory afferents belonging to different modalities, the neural operations that produce an “integrated” output and the interactions with other elements of the circuit or other brain areas ( 2). Behaviorally, response improvement due to multisensory integration is often quantified by evaluating differences in the accuracy and speed of detection, localization and identification of stimuli ( 1, 3). The process of binding the different sensory signals associated to a single coherent event is called multisensory integration ( 1, 2). This is a powerful evolutionary force that led to the development of specialized sensory organs that extract qualitatively different information from a given event.
VIRTUALDUB 1.10.4 VOLUME METER HOW TO
When confronted with potential threats in their environment, animals have to decide and how to perform evasive movements to avoid harm. Finally, we make a direct link between behavioral data and its underlying neural mechanism by reproducing empirical data with an integrate-and-fire computational model of the Mauthner cell. We also show that multisensory stimuli reduce response latency locked to the presentation of the auditory cue. Here we demonstrate that in goldfish visual looms and brief auditory stimuli can be integrated to increase C-start probability and that this enhancement is inversely correlated to the saliency of the cues with weaker auditory cues producing a proportionally stronger multisensory effect. The Mauthner cell can trigger C-starts in response to visual and auditory stimuli allowing to investigate how multisensory integration in a single neuron affects behavioral outcome after threat detection. In fish, an explosive escape behavior known as C-start is driven by an identified neural circuit centered on the Mauthner cell. However, studies showing a direct link between behavioral correlates of multisensory integration and its underlying neural basis are rare. Reducing perceptual ambiguity by integrating multiple sources of sensory information can enhance threat detection and reduce response latency.
Fast and accurate threat detection is critically important for animal survival.