Dissecting the role of the hippocampal-prefrontal circuit in anxiety

The ventral hippocampus (vHPC), medial prefrontal cortex (mPFC), and basolateral amygdala (BLA) are each required for the expression of anxiety-like behavior. Yet the role of each individual element of the circuit is unclear. The projection from the vHPC to the mPFC has been implicated in anxiety-related neural synchrony and spatial representations of aversion. The role of this projection was examined using multi-site neural recordings combined with optogenetic terminal inhibition. Inhibition of vHPC input to the mPFC disrupted anxiety and mPFC representations of aversion, and reduced theta synchrony in a pathway-, frequency- and task-specific manner. Moreover, bilateral, but not unilateral, inhibition altered physiological correlates of anxiety in the BLA, mimicking a safety-like state. These results reveal a specific role for the vHPC-mPFC projection in anxiety-related behavior and the spatial representation of aversive information within the mPFC. Moreover, these data suggested that theta-frequency input from the vHPC plays a causal role in anxiety-like behavior. Next, it was investigated whether optogenetic stimulation of the vHPC-mPFC at a theta frequency was sufficient to increase anxiety. Stimulating the vHPC input to the mPFC with a sinusoidal light pattern at 8 Hz significantly increased anxiety behavior. The anxiogenic effect of vHPC terminal stimulation was frequency- (8 Hz but not 20 Hz) and pattern- (sinusoids but not pulses) specific. To understand how pulses and sinusoidal light modulate mPFC neurons differentially, mPFC pyramidal neurons were recorded both in vitro and in vivo while stimulating vHPC terminals with the same sinusoidal or pulsatile patterns. In vitro, sinusoidal stimulation increased the rate of spontaneous EPSCs, while pulses evoked strong, stimulus-locked EPSCs. In vivo, sinusoidal stimulation of vHPC terminals increased the phase-locking of mPFC single unit spiking to the optical stimulation pattern without changing overall firing rates. Together, these results suggest that sinusoidal stimulation at 8 Hz enhances theta-frequency activity in mPFC neurons as well as anxiety-related behavior. Moreover, they suggest that theta-frequency components of neural activity play a privileged role in vHPC-mPFC communication and hippocampal-dependent forms of anxiety

AlphaTracker: a multi-animal tracking and behavioral analysis tool

Computer vision has emerged as a powerful tool to elevate behavioral research. This protocol describes a computer vision machine learning pipeline called AlphaTracker, which has minimal hardware requirements and produces reliable tracking of multiple unmarked animals, as well as behavioral clustering. AlphaTracker pairs a top-down pose-estimation software combined with unsupervised clustering to facilitate behavioral motif discovery that will accelerate behavioral research. All steps of the protocol are provided as open-source software with graphic user interfaces or implementable with command-line prompts. Users with a graphical processing unit (GPU) can model and analyze animal behaviors of interest in less than a day. AlphaTracker greatly facilitates the analysis of the mechanism of individual/social behavior and group dynamics

Patterns of theta activity in limbic anxiety circuit preceding exploratory behavior in approach-avoidance conflict

Theta oscillations within the hippocampus-amygdala-medial prefrontal cortex (HPC-AMY-mPFC) circuit have been consistently implicated in the regulation of anxiety behaviors, including risk-assessment. To study if theta activity during risk-assessment was correlated with exploratory behavior in an approach/avoidance paradigm we recorded simultaneous local field potentials from this circuit in rats exploring the elevated-plus maze (FPM). Opposing patterns of power variations in the ventral hippocampus (vHPC), basolateral amygdala (BLA), and prelimbic (PrL) mPFC, but not in the dorsal hippocampus (dHPC), during exploratory risk-assessment of the open arms preceded further exploration of the open arms or retreat back to the safer closed arms. The same patterns of theta power variations in the HPC-BLA-mPFC(PrL) circuit were also displayed by animals submitted to chronic unpredictable stress protocol known to induce an anxious state. Diverging patterns of vHPC-mPFC(PrL) theta coherence were also significantly correlated with forthcoming approach or avoidance behavior in the conflict situation in both controls and stressed animals; interestingly, vHPC-BLA, and BLA-mPFC(PrL) theta coherence correlated with future behavior only in stressed animals, underlying the pivotal role of the amygdala on the stress response.LJ was supported by fellowships: SFRH/BD/40459/2007 from the Portuguese Foundation for Science and Technology (FCT); UMINHO/BPD/27/2013 funded by CCDR-N and Programa Operational Regiao Norte (ON.2) from QREN/FEDER; and UMINHO/BPD/63/2015 from Fundacao Calouste Gulbenkian funded project (contract grant number P-139977). Financial support for this work was provided by FEDER funds through the Operational Programme Competitiveness Factors - COMPETE and National Funds through FCT under projects ECOMP-01-0124-FEDER-021145, FCT/PTDC/SAU-ENB/118383/2010, FCOMP-01-0124-FEDER-022674 and POCI-01-0145-FEDER-007038; and by the project NORTE-01-0145-FEDER-000013, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Nature

The ability to associate temporally segregated information and assign positive or negative valence to environmental cues is paramount for survival. Studies have shown that different basolateral amygdala (BLA) projections are potentiated following reward or punishment learning1–7. However, we do not yet understand how valence specific information is routed to the BLA neurons with the appropriate downstream projections. Nor do we understand how to reconcile the subsecond timescales of synaptic plasticity8–11 with the longer timescales separating the predictive cues from their outcomes. Here, we demonstrate that neurotensin (NT) neurons in the paraventricular nucleus of the thalamus (PVT) projecting to the BLA (PVT-BLA:NT) mediate valence assignment by exerting concentration-dependent modulation in BLA during associative learning. We found that optogenetic activation of the PVT-BLA:NT projection promotes reward learning, while PVT-BLA projection-specific Nt gene knockout augments punishment learning. Using genetically encoded calcium and NT sensors, we further revealed that both calcium dynamics within the PVT-BLA:NT projection and NT concentrations in the BLA are enhanced after reward learning and reduced after punishment learning. Finally, we showed that CRISPR-mediated knockout of the Nt gene in the PVT-BLA pathway blunts BLA neural dynamics and attenuates the preference to active behavioral strategies to reward and punishment predictive cues. Taken together, we have identified NT as a neuropeptide that signals valence in the BLA, and showed that NT is a critical neuromodulator that orchestrates positive and negative valence assignment in amygdala neurons by extending valence-specific plasticity to behaviorally-relevant timescales

Alternating Hemiplegia of Childhood-Related Neural and Behavioural Phenotypes in Na+,K+-ATPase α3 Missense Mutant Mice

Missense mutations in ATP1A3 encoding Na(+),K(+)-ATPase α3 have been identified as the primary cause of alternating hemiplegia of childhood (AHC), a motor disorder with onset typically before the age of 6 months. Affected children tend to be of short stature and can also have epilepsy, ataxia and learning disability. The Na(+),K(+)-ATPase has a well-known role in maintaining electrochemical gradients across cell membranes, but our understanding of how the mutations cause AHC is limited. Myshkin mutant mice carry an amino acid change (I810N) that affects the same position in Na(+),K(+)-ATPase α3 as I810S found in AHC. Using molecular modelling, we show that the Myshkin and AHC mutations display similarly severe structural impacts on Na(+),K(+)-ATPase α3, including upon the K(+) pore and predicted K(+) binding sites. Behavioural analysis of Myshkin mice revealed phenotypic abnormalities similar to symptoms of AHC, including motor dysfunction and cognitive impairment. 2-DG imaging of Myshkin mice identified compromised thalamocortical functioning that includes a deficit in frontal cortex functioning (hypofrontality), directly mirroring that reported in AHC, along with reduced thalamocortical functional connectivity. Our results thus provide validation for missense mutations in Na(+),K(+)-ATPase α3 as a cause of AHC, and highlight Myshkin mice as a starting point for the exploration of disease mechanisms and novel treatments in AHC

Selective inhibitory control of pyramidal neuron ensembles and cortical subnetworks by chandelier cells

The neocortex comprises multiple information processing streams mediated by subsets of glutamatergic pyramidal cells (PCs) that receive diverse inputs and project to distinct targets. How GABAergic interneurons regulate the segregation and communication among intermingled PC subsets that contribute to separate brain networks remains unclear. Here we demonstrate that a subset of GABAergic chandelier cells (ChCs) in the prelimbic cortex, which innervate PCs at spike initiation site, selectively control PCs projecting to the basolateral amygdala (BLAPC) compared to those projecting to contralateral cortex (CCPC). These ChCs in turn receive preferential input from local and contralateral CCPCs as opposed to BLAPCs and BLA neurons (the prelimbic cortex-BLA network). Accordingly, optogenetic activation of ChCs rapidly suppresses BLAPCs and BLA activity in freely behaving mice. Thus, the exquisite connectivity of ChCs not only mediates directional inhibition between local PC ensembles but may also shape communication hierarchies between global networks

Lessons from the Stories of Women in Neuroscience.

Women have been contributing to the field of neuroscience since its inception, but their accomplishments are often overlooked. Lack of recognition, among other issues, has led to progressively fewer women at each academic stage; although half of neuroscience graduate students are women, women comprise less than one-third of neuroscience faculty, and even fewer full professors. Those who reach this level continue to struggle to get their work recognized. Women from historically excluded backgrounds are even more starkly underrepresented and face added challenges related to racial, ethnic, and other biases. To increase the visibility of women in neuroscience, promote their voices, and learn about their career journeys, we created Stories of Women in Neuroscience (Stories of WiN). Stories of WiN shares the scientific and personal stories of women neuroscientists with diverse backgrounds, identities, research interests, and at various career stages. From >70 women highlighted thus far, a major theme has emerged: there is not a single archetype of a woman neuroscientist, nor a single path to "success." Yet, through these diverse experiences run common threads, such as the importance of positive early research experiences, managing imposter syndrome, the necessity of work-life balance, and the challenges of fitting into-or resisting-the "scientist mold" within a patriarchal, racialized academic system. These commonalities reveal important considerations for supporting women neuroscientists. Through the lens of women highlighted by Stories of WiN, we explore the similarities among their journeys and detail specific actionable items to help encourage, support, and sustain women in neuroscience