| Figure 2. |
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| A reversal procedure in a visual discrimination task in monkeys reveals responses for LC neurons specific to meaningful stimuli. Target stimuli occur on 10% of trials, and non-target stimuli occur on 90%; stimuli are presented at vertical dashed lines in each histogram. The animal receives a drop of juice when it responds after a target stimulus. a and b: Post-stimulus-time histograms (PSTHs) for response of an LC neuron to green (target), but not to yellow (non-target) stimuli. c and d: Similar PSTHs for the same LC neuron after reversal training such that target stimuli are now yellow and non-target stimuli green. Note that green stimuli (c) no longer elicit responses, whereas yellow stimuli (d) now elicit a small response. Thus, the response is selectively elicited by meaningful stimuli. Calibration bar represents 1 sec. (From ref. 8.) |
published 2000