Browsing by Author "Melville, Natalie"

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    Emotional words evoke region- and valence-specific patterns of concurrent neuromodulator release in human thalamus and cortex
    Batten, Seth R.; Hartle, Alec E.; Barbosa, Leonardo S.; Hadj-Amar, Beniamino; Bang, Dan; Melville, Natalie; Twomey, Tom; White, Jason P.; Torres, Alexis; Celaya, Xavier; McClure, Samuel M.; Brewer, Gene A.; Lohrenz, Terry; Kishida, Kenneth T.; Bina, Robert W.; Witcher, Mark R.; Vannucci, Marina; Casas, Brooks; Chiu, Pearl; Montague, P. Read; Howe, William M. (Elsevier, 2025-01-28)
    Words represent a uniquely human information channel—humans use words to express thoughts and feelings and to assign emotional valence to experience. Work from model organisms suggests that valence assignments are carried out in part by the neuromodulators dopamine, serotonin, and norepinephrine. Here, we ask whether valence signaling by these neuromodulators extends to word semantics in humans by measuring sub-second neuromodulator dynamics in the thalamus (N = 13) and anterior cingulate cortex (N = 6) of individuals evaluating positive, negative, and neutrally valenced words. Our combined results suggest that valenced words modulate neuromodulator release in both the thalamus and cortex, but with regionand valence-specific response patterns, as well as hemispheric dependence for dopamine release in the anterior cingulate. Overall, these experiments provide evidence that neuromodulator-dependent valence signaling extends to word semantics in humans, but not in a simple one-valence-per-transmitter fashion.
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    Noradrenaline tracks emotional modulation of attention in human amygdala
    Bang, Dan; Luo, Yi; Barbosa, Leonardo S.; Batten, Seth R.; Hadj-Amar, Beniamino; Twomey, Thomas; Melville, Natalie; White, Jason P.; Torres, Alexis; Celaya, Xavier; Ramaiah, Priya; McClure, Samuel M.; Brewer, Gene A.; Bina, Robert W.; Lohrenz, Terry; Casas, Brooks; Chiu, Pearl H.; Vannucci, Marina; Kishida, Kenneth T.; Witcher, Mark R.; Montague, P. Read (Elsevier, 2023-11-20)
    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. The LC-NA system is believed to regulate arousal and attention and is a pharmacological target in multiple clinical conditions. 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, and receives dense LC-NA projections, 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, 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, supported a hypothesis that pupil-NA coupling changes with cognitive state, with the pupil and NA estimates being positively correlated for oddball stimuli in a high-arousal but not a lowarousal state. Our study provides proof of concept that neuromodulator monitoring is now possible using depth electrodes in standard clinical use.