The Amygdala Network for Processing Itch in Human Brains

Abstract

Itch is an unpleasant and aversive somatosensory experience. These negative emotions significantly affect mental health in patients with chronic itch; it is therefore important to understand the brain mechanism of negative emotions due to itch. The amygdala is a key hub of networks regulating negative emotions due to itch. However, the exact network involved in this process is unknown. This study used functional magnetic resonance imaging to investigate the amygdala network processing itch in 25 healthy subjects. Brain activity was measured during electrical itch stimuli using functional magnetic resonance imaging. During itch stimuli the amygdala exhibited increased functional connectivity with key brain regions of the serotonergic system responsible for negative emotions (the medial habenula and the median raphe nucleus) and with the memory system, which is responsible for consolidating emotional experiences (the parahippocampus and perirhinal cortex). The serotonergic and memory systems may become therapeutic targets to prevent or reduce diminished mental health commonly seen in chronic itch patients.

Cellular, circuit and transcriptional framework for modulation of itch in the central amygdala

“…We used both optogenetics and chemogenetics in a complementary manner to confirm these results. Conceptually, our findings seem to reconcile prior work (Chen et al, 2016;Mochizuki et al, 2020;Papoiu et al, 2014;Sanders et al, 2019;Sun et al, 2009;Vierow et al, 2015) suggesting a pivotal role of CeA neurons in pruritic processing. The CeA is known to be involved in threat detection, and to produce adaptive responses when organisms encounter threatening conditions (Fadok et al, 2018;Grundemann and Luthi, 2015;LeDoux and Daw, 2018).…”

Cellular, Circuit and Transcriptional Framework for Modulation of Itch in the Central Amygdala

“…We used both optogenetics and chemogenetics in a complementary manner to confirm these results. Conceptually, our findings seem to reconcile prior work (Chen et al, 2016; Mochizuki et al, 2020; Papoiu et al, 2014; Sun et al, 2009; Vierow et al, 2015) suggesting a pivotal role of CeA neurons in pruritic processing. The CeA is known to be involved in threat detection, and to produce adaptive responses when organisms encounter threatening conditions (Fadok et al, 2018; Grundemann and Luthi, 2015; LeDoux and Daw, 2018).…”

Functional Magnetic Resonance Imaging and Applications in Dermatology

“…With advancements in statistical analysis and image processing, the most recent fMRI studies in dermatology are focusing on exploring the functional connectivity of brain regions associated with itch. Initial studies from Mochizuki et al. (2020 , 2019) are the first to identify key networks in processing itch.…”

“…With advancements in the statistical analysis and image processing, the most recent fMRI studies in dermatology are focusing on exploring the functional connectivity of brain regions associated with itch. Initial studies from Mochizuki and collegeues are the first to identify key networks in processing itch (Mochizuki et al, 2020, Mochizuki et al, 2019. In their most recent study on functional networks of pruritus, Mochizuki et al highlight connections with the amygdala and J o u r n a l P r e -p r o o f the serotonergic and memory systems possibly representing therapeutic targets (Mochizuki et al, 2020).…”

“…Initial studies from Mochizuki and collegeues are the first to identify key networks in processing itch (Mochizuki et al, 2020, Mochizuki et al, 2019. In their most recent study on functional networks of pruritus, Mochizuki et al highlight connections with the amygdala and J o u r n a l P r e -p r o o f the serotonergic and memory systems possibly representing therapeutic targets (Mochizuki et al, 2020).…”