Source Paper
A primary acoustic startle circuit: lesion and stimulation studies
M Davis, DS Gendelman, MD Tischler, PM Gendelman
Journal of Neuroscience • 1982
Source Paper
M Davis, DS Gendelman, MD Tischler, PM Gendelman
Journal of Neuroscience • 1982
The latency of the acoustic startle reflex in the rat is 8 msec, measured from tone onset to the beginning of the electromyographic response in the hindleg. This extremely short latency indicates that only a few synapses could be involved in some primary acoustic startle circuit. Acoustic startle is being used as a model system for studying habituation, sensitization, prepulse inhibition, classical conditioning, fear or anxiety, and drug effects on behavior. The present study attempted to delineate a short latency acoustic startle circuit, since this would provide critical information for further study in all of these areas. Bilateral lesions of the ventral cochlear nucleus, which receives the primary auditory input, abolish acoustic startle. Electrical, single pulse stimulation of the ventral cochlear nucleus elicits startle-like responses with a latency of about 7 msec. Bilateral lesions of the dorsal and ventral nuclei of the lateral lemniscus, which receive direct input from the ventral cochlear nuclei, abolish acoustic startle. Electrical stimulation of these nuclei elicits startle-like responses with a latency of about 6 msec. Bilateral lesions of ventral regions of the nucleus reticularis pontis caudalis, which contain cell bodies that give rise to the reticulospinal tract, abolish acoustic startle. Electrical stimulation of these points elicits startle-like responses with a latency of about 5 msec. Reaction product from horseradish peroxidase iontophoresed into this area is found in the nuclei of the lateral lemniscus. In contrast, lesions of the dorsal cochlear nuclei, vestibular nuclei, nucleus reticularis pontis oralis, nucleus reticularis gigantocellularis, and dorsal regions of the nucleus reticularis pontis caudalis fail to abolish acoustic startle. Also, “startle” cannot be elicited electrically from these areas. The data suggest that a primary acoustic startle circuit in the rat consists of auditory nerve, ventral cochlear nucleus, nuclei of the lateral lemniscus, nucleus reticularis pontis caudalis, spinal interneuron, lower motor neuron, and muscles. Hence, five synapses, plus the neuromuscular junction, are probably involved.
Objective: To delineate a primary acoustic startle circuit in rats by determining which brain regions are critical for the acoustic startle reflex through bilateral lesion studies
Gather these items before starting the experiment. Check off items as you prepare.
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Create bilateral lesions of the ventral cochlear nucleus, which receives primary auditory input
Note: This lesion abolishes acoustic startle reflex
“Bilateral lesions of the ventral cochlear nucleus, which receives the primary auditory input, abolish acoustic startle.”
Record electromyographic response in the hindleg following acoustic stimulus to measure startle reflex latency
Note: Normal latency is approximately 8 msec from tone onset to beginning of EMG response
“The latency of the acoustic startle reflex in the rat is 8 msec, measured from tone onset to the beginning of the electromyographic response in the hindleg.”
Apply single pulse electrical stimulation to the ventral cochlear nucleus and record resulting responses
Note: Stimulation elicits startle-like responses with latency of approximately 7 msec
“Electrical, single pulse stimulation of the ventral cochlear nucleus elicits startle-like responses with a latency of about 7 msec.”
Create bilateral lesions of the dorsal and ventral nuclei of the lateral lemniscus, which receive direct input from ventral cochlear nuclei
Note: These lesions abolish acoustic startle
“Bilateral lesions of the dorsal and ventral nuclei of the lateral lemniscus, which receive direct input from the ventral cochlear nuclei, abolish acoustic startle.”
Apply single pulse electrical stimulation to the dorsal and ventral nuclei of the lateral lemniscus
Note: Stimulation elicits startle-like responses with latency of approximately 6 msec
“Electrical stimulation of these nuclei elicits startle-like responses with a latency of about 6 msec.”
Create bilateral lesions of ventral regions of the nucleus reticularis pontis caudalis, which contain cell bodies giving rise to the reticulospinal tract
Note: These lesions abolish acoustic startle
“Bilateral lesions of ventral regions of the nucleus reticularis pontis caudalis, which contain cell bodies that give rise to the reticulospinal tract, abolish acoustic startle.”
Apply single pulse electrical stimulation to ventral regions of the nucleus reticularis pontis caudalis
Note: Stimulation elicits startle-like responses with latency of approximately 5 msec
“Electrical stimulation of these points elicits startle-like responses with a latency of about 5 msec.”
Iontophorese horseradish peroxidase into nucleus reticularis pontis caudalis to trace neural connections
Note: Reaction product is found in the nuclei of the lateral lemniscus, confirming connectivity
“Reaction product from horseradish peroxidase iontophoresed into this area is found in the nuclei of the lateral lemniscus.”
Create bilateral lesions of dorsal cochlear nuclei, vestibular nuclei, nucleus reticularis pontis oralis, nucleus reticularis gigantocellularis, and dorsal regions of nucleus reticularis pontis caudalis as negative controls
Note: These lesions fail to abolish acoustic startle, indicating these regions are not critical for the reflex
“Lesions of the dorsal cochlear nuclei, vestibular nuclei, nucleus reticularis pontis oralis, nucleus reticularis gigantocellularis, and dorsal regions of the nucleus reticularis pontis caudalis fail to abolish acoustic startle.”
Attempt electrical stimulation of dorsal cochlear nuclei, vestibular nuclei, nucleus reticularis pontis oralis, nucleus reticularis gigantocellularis, and dorsal regions of nucleus reticularis pontis caudalis
Note: Startle responses cannot be elicited electrically from these areas
“Also, "startle" cannot be elicited electrically from these areas.”
None specified