Bilateral Lesion of Lateral Lemniscus Nuclei
Objective: To delineate a primary acoustic startle circuit by performing bilateral lesions of the dorsal and ventral nuclei of the lateral lemniscus and assessing their role in acoustic startle responses
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Protocol Steps
Bilateral lesion of dorsal and ventral nuclei of the lateral lemniscus
Create bilateral lesions of the dorsal and ventral nuclei of the lateral lemniscus in rats
Note: These nuclei receive direct input from the ventral cochlear nuclei
View evidence from paper
“Bilateral lesions of the dorsal and ventral nuclei of the lateral lemniscus, which receive direct input from the ventral cochlear nuclei, abolish acoustic startle.”
Measure acoustic startle response latency
Record electromyographic response in the hindleg following acoustic stimulus to measure startle reflex latency
Note: Latency is measured from tone onset to the beginning of the electromyographic response
View evidence from paper
“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.”
Perform electrical stimulation of lesioned nuclei
Apply single pulse electrical stimulation to the dorsal and ventral nuclei of the lateral lemniscus and record resulting responses
Note: Electrical stimulation of these nuclei elicits startle-like responses
View evidence from paper
“Electrical stimulation of these nuclei elicits startle-like responses with a latency of about 6 msec.”
Perform horseradish peroxidase iontophoresis
Iontophorese horseradish peroxidase into the nucleus reticularis pontis caudalis to trace neural connections to the nuclei of the lateral lemniscus
Note: Reaction product is used to identify connections between neural structures
View evidence from paper
“Reaction product from horseradish peroxidase iontophoresed into this area is found in the nuclei of the lateral lemniscus.”