Source Paper
Locus coeruleus neurons in monkey are selectively activated by attended cues in a vigilance task
G Aston-Jones, J Rajkowski, P Kubiak, T Alexinsky
Journal of Neuroscience • 1994
Oddball Visual Discrimination Task
Objective: To record impulse activity from locus coeruleus neurons in monkeys performing an oddball visual discrimination task and examine selective activation by attended cues in a vigilance task
Protocol Steps
Setup extracellular recording
Prepare extracellular recording apparatus to record impulse activity from noradrenergic neurons in the nucleus locus coeruleus of the monkey
Note: 47 single-cell and 126 multicell recordings were obtained across four animals
View evidence from paper
“Impulse activity was recorded extracellularly from noradrenergic neurons in the nucleus locus coeruleus (LC; 47 single-cell and 126 multicell recordings) of four cynomolgus monkeys”
Present visual stimuli on video display
Display target cues (CS+) and nontarget cues (CS-) on video display. Target cues appear infrequently at 10-20% of trials and are randomly intermixed with nontarget stimuli
Note: Target cues are infrequent (10-20% of trials) and randomly intermixed with nontarget stimuli
View evidence from paper
“an infrequent (10–20% of trials) target cue (CS+) that was randomly intermixed with nontarget (CS-) stimuli presented on a video display”
Require lever release response
Subject must release lever rapidly in response to target cue (CS+) presentation to obtain juice reward
Note: Lever release must occur in response to target cues; other task events (juice reward, lever release, fix-spot stimuli, nontarget stimuli) do not elicit consistent LC neuron responses
View evidence from paper
“subjects were required to release a lever rapidly in response to an infrequent target cue (CS+)”
Record neural responses to task events
Record extracellular impulse activity from LC neurons during task performance, monitoring responses to target cues, nontarget cues, juice reward, lever release, and fix-spot stimuli
Note: All LC neurons examined were phasically and selectively activated by target cues. Other task events elicited no consistent response. In one animal, nontarget cues phasically inhibited LC neurons
View evidence from paper
“All LC neurons examined were phasically and selectively activated by target cues in this task. Other task events elicited no consistent response from these neurons”
Measure response latencies
Measure latency of LC neural responses to target cues and latency of behavioral responses (lever release) to same target cues
Note: Mean LC response latency was 90.7 msec, occurring approximately 200 msec prior to behavioral response. Positive correlation (r = 0.30, p < 0.0001) found between LC response latency and behavioral response latency
View evidence from paper
“Phasic LC excitatory responses to target cues in this task occurred at a relatively short latency (mean = 90.7 msec), approximately 200 msec prior to the behavioral response”
Monitor performance-dependent response magnitude
Track LC response magnitudes in relation to behavioral performance, noting changes during epochs of poor performance
Note: LC response magnitudes were substantially attenuated during epochs of poor performance (high false alarm rate)
View evidence from paper
“LC response magnitudes varied with behavioral performance, being substantially attenuated during epochs of poor performance (high false alarm rate)”
Analyze temporal dynamics during prolonged performance
Examine changes in LC response magnitude over time during extended task performance exceeding 90 minutes
Note: Responses became reduced in magnitude over time during prolonged task performance, in parallel with behavioral performance decrement
View evidence from paper
“responses became reduced in magnitude over time during prolonged task performance (> 90 min), in parallel with a behavioral performance decrement”