A whole-brain connectivity map of mouse insular cortex

Abstract

The insular cortex (IC) plays key roles in emotional and regulatory brain functions and is affected across psychiatric diseases. However, the brain-wide connections of the mouse IC have not been comprehensively mapped. Here we traced the whole-brain inputs and outputs of the mouse IC across its rostro-caudal extent. We employed cell-type specific monosynaptic rabies virus tracings to characterize afferent connections onto either excitatory or inhibitory IC neurons, and adeno-associated viral tracings to label excitatory efferent axons. While the connectivity between the IC and other cortical regions was highly bidirectional, the IC connectivity with subcortical structures was often unidirectional, revealing prominent cortical-to-subcortical or subcortical-to-cortical pathways. The posterior and medial IC exhibited resembling connectivity patterns, while the anterior IC connectivity was distinct, suggesting two major functional compartments. Our results provide insights into the anatomical architecture of the mouse IC and thus a structural basis to guide investigations into its complex functions.

Parvalbumin interneuron inhibition onto anterior insula neurons projecting to the basolateral amygdala orchestrates aversive taste memory retrieval

“…Several upstream circuits might be involved in the modulation aIC PV activity during CTA retrieval, including thalamocortical and amygdalocortical projections 55 , as well as the parabrachial nucleus 14 and basal forebrain 56 . Recent evidence from brain-wide connectivity studies of the mouse insular cortex, corroborate that the portion of the IC examined in our studies is indeed home to local PV interneurons, and is bi-directionally connected with the thalamus and amygdala through excitatory projections 57 . Alternatively, activity-dependent plasticity in aIC-BLA projecting neurons itself 10, 11 , might guide the entrainment and subsequent recruitment of PV interneurons during retrieval 21, 24, 30 .…”

Dissociable Roles of Pallidal Neuron Subtypes in Regulating Motor Patterns

“…On the other hand, it is clear that the inhibitory projection to the STN (and substantial pars reticulata) mediates the motor-promoting effects, and it is consistent with the established relationship between STN activity and movement suppression (Hamani et al, 2004; Aron and Poldrack, 2006; Aron et al, 2007; Eagle et al, 2008; Schmidt et al, 2013; Schweizer et al, 2014; Fife et al, 2017; Wessel and Aron, 2017). In addition to the established literature demonstrating that the GPe sends inhibitory signals to the input and output nuclei of the basal ganglia (Jessell et al, 1978; Mink, 1996; Smith et al, 1998; Kita, 2007; Hegeman et al, 2016; Adam et al, 2020), recent studies highlight the existence of cortico-pallido-cortical loops (Naito and Kita, 1994; Chen et al, 2015; Saunders et al, 2015; Schwarz et al, 2015; Ahrlund-Richter et al, 2019; Karube et al, 2019; Abecassis et al, 2020; Adkins et al, 2020; Anastasiades et al, 2020; Clayton et al, 2020; Gehrlach et al, 2020; Lee et al, 2020; Muñoz-Castañeda et al, 2020; Garcia et al, 2021). However, the precise circuitry has yet to be defined.…”

Parvalbumin interneuron inhibition onto anterior insula neurons projecting to the basolateral amygdala drives aversive taste memory retrieval

“…57 Recent evidence from brain-wide connectivity studies of the mouse insular cortex corroborate that the portion of the IC examined in our studies is indeed home to local PV interneurons and is bi-directionally connected with the thalamus and amygdala through excitatory projections. 58 Alternatively, activity-dependent plasticity in aIC-BLA-projecting neurons itself 10,11 might guide the entrainment and subsequent recruitment of PV interneurons during retrieval. 21,24,30 Even though the primary focus of our studies was the role of aIC PV in taste memory retrieval, we do not presume their role is limited to this function.…”