Reciprocal connectivity between secondary auditory cortical field and amygdala in mice

Abstract

Recent studies have examined the feedback pathway from the amygdala to the auditory cortex in conjunction with the feedforward pathway from the auditory cortex to the amygdala. However, these connections have not been fully characterized. Here, to visualize the comprehensive connectivity between the auditory cortex and amygdala, we injected cholera toxin subunit b (CTB), a bidirectional tracer, into multiple subfields in the mouse auditory cortex after identifying the location of these subfields using flavoprotein fluorescence imaging. After injecting CTB into the secondary auditory field (A2), we found densely innervated CTB-positive axon terminals that were mainly located in the lateral amygdala (La), and slight innervations in other divisions such as the basal amygdala. Moreover, we found a large number of retrogradely-stained CTB-positive neurons in La after injecting CTB into A2. When injecting CTB into the primary auditory cortex (A1), a small number of CTB-positive neurons and axons were visualized in the amygdala. Finally, we found a near complete absence of connections between the other auditory cortical fields and the amygdala. These data suggest that reciprocal connections between A2 and La are main conduits for communication between the auditory cortex and amygdala in mice.

Inhibitory gating of coincidence-dependent sensory binding in secondary auditory cortex

“…One interesting possibility is that the broad and heterogeneous tuning properties of A2 neurons give them the ability to integrate sounds over a broader range of spectral and temporal space than A1 neurons. AuV-TeA area may possess subnetworks that extract distinct spectro-temporal structures, including harmonics, sweeps, and vocalizations, and serve as a gateway for associating this information with behavioral relevance 50 , analogous to the “ventral auditory stream” in humans and nonhuman primates 51 , 52 .…”

Potentiated cholinergic and corticofugal inputs support reorganized sensory processing in the basolateral amygdala during auditory threat acquisition and retrieval

“…The BLA and HO-AC are reciprocally interconnected, where the HO-AC both sends and receives approximately three time more input with the BLA than AuP, as shown here and in prior work (Hintiryan et al, 2021; LeDoux et al, 1991; Romanski and Ledoux, 1993; Tsukano et al, 2019; Yang et al, 2016). We used the spike-triggered LFP to demonstrate that the reciprocal anatomical connectivity between HO-AC and BLA is mirrored by reciprocal functional connectivity, such that a spike in either region was associated with the maximal negativity in the LFP 5-10ms later, the temporal lag suggesting that the major contributor is the inter-area communication rather than shared common inputs.…”

“…BLA neurons receive direct anatomical inputs from the HO-AC but also directly project to the HO-AC (Tasaka et al, 2020; Tsukano et al, 2019). To determine whether enhanced functional connectivity between the HO-AC and BLA during threat memory is bi-directional or asymmetric, we also calculated the spike-triggered LFP from BLA to HO-AC ( Figure 5F ).…”

Distinct electrophysiological properties of long‐range GABAergic and glutamatergic neurons from the lateral amygdala to the auditory cortex of the mouse

“…More recently, Tsukano et al. (2019) have demonstrated reciprocal connectivity between secondary auditory cortex and amygdala in mice. However, little information is known about these amygdala‐cortical neurons' anatomical and electrophysiological properties.…”