The anterolateral group of the bed nucleus of the stria terminalis (BNST(ALG)) plays a critical role in a diverse array of behaviors, although little is known of the physiological properties of neurons in this region. Using whole cell patch-clamp recordings from rat BNST(ALG) slices in vitro, we describe three distinct physiological cell types. Type I neurons were characterized by the presence of a depolarizing sag in response to hyperpolarizing current injection that resembled activation of the hyperpolarization-activated cation current I(h) and a regular firing pattern in response to depolarizing current injection. Type II neurons exhibited the same depolarizing sag in response to hyperpolarizing current injection, but burst-fired in response to depolarizing current injection, which was indicative of the activation of the low-threshold calcium current I(T). Type III neurons did not exhibit a depolarizing sag in response to hyperpolarizing current injection, but instead exhibited a fast time-independent rectification that became more pronounced with increased amplitude of hyperpolarizing current injection, and was indicative of activation of the inwardly rectifying potassium current I(K(IR)). Type III neurons also exhibited a regular firing pattern in response to depolarizing current. Using voltage-clamp analysis we further characterized the primary active currents that shaped the physiological properties of these distinct cell types, including I(h), I(T), I(K(IR)), the voltage-dependent potassium current I(A), and the persistent sodium current I(NaP). The functional relevance of each cell type is discussed in relation to prior anatomical studies, as well as how these currents may interact to modulate neuronal activity within the BNST(ALG).

The basolateral amygdala (BLA) is critical for the generation of emotional behavior and the formation of emotional memory. Understanding the neuronal mechanisms that contribute to emotional information processing in the BLA will ultimately require knowledge of the anatomy and physiology of its constituent neurons. Two major cell classes exist in the BLA, pyramidal projection neurons and nonpyramidal interneurons. Although the properties of projection neurons have been studied in detail, little is known about the properties of BLA interneurons. We have used whole-cell patch clamp recording techniques to examine the physiological properties of 48 visually identified putative interneurons from the rat anterior basolateral amygdalar nucleus. Here, we report that BLA interneurons can be differentiated into four electrophysiologically distinct subtypes based on their intrinsic membrane properties and their response to afferent synaptic input. Interneuron subtypes were named according to their characteristic firing pattern generated in response to transient depolarizing current injection and were grouped as follows: 1) burst-firing interneurons (n = 13), 2) regular-firing interneurons (n = 11), 3) fast-firing interneurons (n = 10), and 4) stutter-firing interneurons (n = 14). Post hoc histochemical visualization confirmed that all 48 recorded neurons had morphological properties consistent with their being local circuit interneurons. Moreover, by using triple immunofluorescence (for biocytin, calcium-binding proteins, and neuropeptides) in conjunction with patch clamp recording, we further demonstrated that over 60% of burst-firing and stutter-firing interneurons also expressed the calcium-binding protein parvalbumin (PV(+)). These data demonstrate that interneurons of the BLA show both physiological and neurochemical diversity. Moreover, we demonstrate that the burst- and stutter-firing patterns positively correlate with PV(+) immunoreactivity, suggesting that these neurons may represent functionally distinct subpopulations.

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Activation of group II metabotropic glutamate receptors (mGluR2/3) in the amygdala plays a critical role in the regulation of fear and anxiety states. Previous studies using nonselective agonists have suggested this action can result from activation of either pre- or postsynaptic mGluR2/3. Here, we have used a combination of whole-cell patch clamp recording with highly selective agonists (LY354740 and LY379268) and immunoelectron microscopy to examine structure-function relationships for mGluR2/3 in the basolateral amygdala (BLA) and bed nucleus of the stria terminalis (BNST). Stimulation of mGluR2/3 evoked a direct, TTX-insensitive membrane hyperpolarization in all BLA projection neurons tested, but only about half of BNST neurons. The membrane hyperpolarization was mediated by activation of an outward potassium current or blockade of a tonically active inward I(h) current in different groups of BLA neurons. In both regions, mGluR2/3 caused a long-lasting reduction of glutamate release from presynaptic afferent terminals even at concentrations that failed to elicit a direct postsynaptic response. The localization of mGluR2/3 differed regionally, with postsynaptic labeling significantly more common in BLA than BNST, corresponding to the strength of postsynaptic responses recorded there. Our results demonstrate a complex role for mGluR2/3 receptors in modulating anxiety circuitry, including direct inhibition and reduction of excitatory drive. The combination of direct inhibition of projection neurons within the BLA and suppression of excitatory neurotransmission in the BNST may be responsible for the anxiolytic actions of group II mGluR agonists.

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This study reviewed the impact of telemedicine on treatment retention in Medications for Opioid Use Disorder (MOUD) with buprenorphine treatment program during the coronavirus disease 2019 (COVID-19) pandemic. Electronic health records of active patients in MOUD with buprenorphine treatment program were reviewed from July 1, 2019, to June 30, 2020. Data were divided into four groups of 3-months’ time points to calculate and compare treatment retention in the baseline, pre-COVID, and in-COVID groups. The percentage of treatment retention with a 95% confidence interval was calculated using University of California San Franciso- Clinical and Translational Science Institute (UCSF-CTSI) sample size calculator tool. This study presents data suggesting that telemedicine is efficacious in retaining patients in MOUD. Telemedicine is an alternative to face-to-face treatment delivery for MOUD with buprenorphine treatment. It should be available to provide services after the pandemic as well.