Acoustic Startle Response Characterization
Objective: Characterize physiological properties of giant PnC neurons in response to acoustic stimuli including response latencies, thresholds, frequency tuning, and habituation to understand the neuronal basis of the acoustic startle response
Gather these items before starting the experiment. Check off items as you prepare.
Equipment2
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Materials1
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Protocol Steps
Retrograde and anterograde tracing
Employ retrograde and anterograde tracing techniques to identify possible sources of input and efferent targets of giant PnC neurons
Note: First step of the study to map connectivity
View evidence from paper
“In a first step of this study, we employed retrograde and anterograde tracing techniques to identify the possible sources of input and the efferent targets of these neurons”
Intracellular recording in vivo
Perform intracellular recordings from giant PnC neurons in vivo to investigate physiological properties in response to acoustic stimuli
Note: Recordings followed by HRP injection for morphological identification
View evidence from paper
“In a second step of this study, we performed intracellular recordings in vivo, followed by subsequent injections of HRP for morphological identification”
Measure response latencies
Measure the latency of neuronal responses to acoustic stimuli in giant PnC neurons
Note: Response latencies are a key characteristic feature of the ASR
View evidence from paper
“they receive short-latency auditory input”
Determine firing thresholds
Determine the firing thresholds of giant PnC neurons in response to acoustic stimuli
Note: Giant PnC neurons have high firing thresholds
View evidence from paper
“they have high firing thresholds and broad frequency tuning”
Characterize frequency tuning
Analyze the frequency tuning properties of giant PnC neurons across different acoustic frequencies
Note: Neurons show broad frequency tuning
View evidence from paper
“they have high firing thresholds and broad frequency tuning”
Test stimulus rise time sensitivity
Assess sensitivity of giant PnC neurons to changes in stimulus rise time of acoustic stimuli
Note: Neurons are sensitive to stimulus rise time variations
View evidence from paper
“they are sensitive to changes in stimulus rise time and to paired-pulse stimulation”
Perform paired-pulse stimulation
Apply paired acoustic pulses to assess neuronal sensitivity to paired-pulse stimulation
Note: Neurons respond to paired-pulse stimulation patterns
View evidence from paper
“they are sensitive to changes in stimulus rise time and to paired-pulse stimulation”
Assess habituation to repetitive stimulation
Apply repetitive acoustic stimulation and measure habituation of neuronal responses over time
Note: Repetitive acoustic stimulation results in habituation of response
View evidence from paper
“repetitive acoustic stimulation results in habituation of their response”
Test amygdaloid modulation
Assess whether amygdaloid activity enhances the response of giant PnC neurons to acoustic stimuli
Note: Amygdaloid activity enhances neuronal response to acoustic stimuli
View evidence from paper
“amygdaloid activity enhances their response to acoustic stimuli”
Morphological identification
Identify morphological characteristics of recorded neurons and determine if they are reticulospinal cells
Note: Most giant PnC neurons are reticulospinal cells with axon collaterals in reticular formation and motoneuron pools
View evidence from paper
“Anterograde tracing showed that most giant PnC neurons are reticulospinal cells. Axon collaterals and terminal arbors were found in the reticular formation as well as in cranial and spinal motoneuron pools”