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The noradrenaline (NA) system is one of the brain's major neuromodulatory systems; it originates in a small midbrain nucleus, the locus coeruleus (LC), and projects widely throughout the brain. 1,2 The LC-NA system is believed to regulate arousal and attention 3,4 and is a pharmacological target in multiple clinical conditions. 5,6,7 Yet our understanding of its role in health and disease has been impeded by a lack of direct recordings in humans. Here, we address this problem by showing that electrochemical estimates of sub-second NA dynamics can be obtained using clinical depth electrodes implanted for epilepsy monitoring. We made these recordings in the amygdala, an evolutionarily ancient structure that supports emotional processing 8,9 and receives dense LC-NA projections, 10 while patients (n = 3) performed a visual affective oddball task. The task was designed to induce different cognitive states, with the oddball stimuli involving emotionally evocative images, 11 which varied in terms of arousal (low versus high) and valence (negative versus positive). Consistent with theory, the NA estimates tracked the emotional modulation of attention, with a stronger oddball response in a high-arousal state. Parallel estimates of pupil dilation, a common behavioral proxy for LC-NA activity, 12 supported a hypothesis that pupil-NA coupling changes with cognitive state, 13,14 with the pupil and NA estimates being positively correlated for oddball stimuli in a high-arousal but not a low-arousal state. Our study provides proof of concept that neuromodulator monitoring is now possible using depth electrodes in standard clinical use. • Sub-second neuromodulator dynamics can be measured using clinical depth electrodes • Noradrenaline dynamics in human amygdala reflect attention and arousal • Coupling between noradrenaline and pupil dilation depends on cognitive state Bang et al. demonstrate that electrochemical estimates of sub-second neuromodulator dynamics can be obtained in humans using clinical depth electrodes. They show that noradrenaline tracks the emotional modulation of attention and that the coupling between noradrenaline and pupil dilation—a common behavioral proxy for noradrenaline—depends on cognitive state. [ABSTRACT FROM AUTHOR]