Must-Read Neural Circuit Papers in October 2017

nVista, ca2+ Calcium Imaging Technology

October brought with it cooler air and many more amazing neural circuit papers! Three of the papers on our must-read list used Inscopix nVista technology in freely behaving mice. We scour the journals and put links here for your convenience. Enjoy!

1. Parvalbumin and Somatostatin Interneurons Control Different Space-Coding Networks in the Medial Entorhinal Cortex by Chenglin Miao, Qichen Cao, May-Britt Moser, Edvard I. Moser. Cell.

They selectively silenced Parvalbumin (PV) or somatostatin (SOM) interneurons in the medial entorhinal cortex and examined the effects on the spatial and directional firing properties in the medial entorhinal cortex. Indeed, they found dissociable roles between the two cell types. “PV interneurons maintain spatially periodic firing in grid cells. PV interneurons are necessary for speed tuning in entorhinal speed cells. SOM interneurons maintain selectivity of aperiodic spatial cells. PV and SOM cells regulate discrete subsets of spatially tuned entorhinal cell types.”

Read more here

2. Neuronal Representation of Social Information in the Medial Amygdala of Awake Behaving Mice by Ying Li, Alexander Mathis, Benjamin F. Grewe, Jessica A. Osterhout, Biafra Ahanonu, Mark J. Schnitzer, Venkatesh N. Murthy, Catherine Dulac. Cell.

Calcium imaging in freely behaving mice (nVista) reveals differences in the encoding of social stimuli in the medial amygdala. Most notably, sexual experience triggered lasting changes in ensembles of neurons representing each sex. They also showed a role for oxytocin in this process in males.

Read more here and here and here

3. The Anterior Insular Cortex→Central Amygdala Glutamatergic Pathway Is Critical to Relapse after Contingency Management by Marco Venniro, Daniele Caprioli, Michelle Zhang, Leslie R. Whitaker, Shiliang Zhang, Brandon L. Warren, Carlo Cifani, Nathan J. Marchant, Ofer Yizhar, Jennifer M. Bossert, Cristiano Chiamulera, Marisela Morales, Yavin Shaham. Neuron.

They used a novel rat model to show that central amygdala (CeA) activity is critical to drug relapse after choice-based contingency management. Their results demonstrate a critical role of dopamine-antagonist-mediated neuronal activity in the CeA that is controlled by ventral anterior insular cortex AIV→CeA glutamatergic projections in relapse to methamphetamine seeking after voluntary abstinence.

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4. Dynamics of Gut-Brain Communication Underlying Hunger by Lisa R. Beutler, Yiming Chen, Jamie S. Ahn, Yen-Chu Lin, Rachel A. Essner, Zachary A. Knight. Neuron.

In this paper, they show that intragastric nutrient infusion inhibits hunger-promoting AgRP neurons in awake, behaving mice in a way proportional to calories, but independent of macronutrient identity or nutritional state. This effect was regulated in a necessary or sufficient way by three gastrointestinal signals—serotonin, CCK, and PYY. In contrast, the hormone leptin induced a slow modulation that developed over hours and was required for inhibition of feeding. “These findings reveal how layers of visceral signals operating on distinct timescales converge on hypothalamic feeding circuits to generate a central representation of energy balance.”

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5. Development and Refinement of Functional Properties of Adult-Born Neurons

by Jenelle L. Wallace, Martin Wienisch, Venkatesh N. Murthy. Neuron.

This is a nice study on the functional life history of an adult-born granule cell (abGC) in the olfactory bulb using multiphoton imaging in awake and anesthetized mice. Their findings indicate that with maturation, responsiveness of abGCs decreases while a subpopulation of cells becomes more broadly tuned. They also found that olfactory enrichment during the early period of heightened odor responses could extend the window for the critical period.

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6. Functional Convergence at the Retinogeniculate Synapse by Elizabeth Y. Litvina, Chinfei Chen. Neuron.

Here they use optogenetics and a computational simulation to determine the number of functionally relevant retinogeniculate (RGC) inputs onto thalamocortical (TC) neurons in mice. Their results indicate that an average of ten RGCs converge onto a mature TC neuron, in contrast to >30 inputs before developmental refinement. This suggests a greater thalamic contribution to visual processing.

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7. Social behaviour shapes hypothalamic neural ensemble representations of conspecific sex by Ryan Remedios, Ann Kennedy, Moriel Zelikowsky, Benjamin F. Grewe, Mark J. Schnitzer & David J. Anderson. Nature.

The authors used nVista Ca2+ imaging in freely behaving male mice as they interacted with male and female intruders. By recording the ensemble activity in the ventromedial hypothalamus while animals interacted with conspecifics, they saw that instead of being hardwired, the ensembles gradually separated as the mice acquired social and sexual experience.

Read more here and here

8. Altered cerebellar connectivity in autism and cerebellar-mediated rescue of autism-related behaviors in mice by Catherine J. Stoodley, Anila M. D’Mello, Jacob Ellegood, Vikram Jakkamsetti, Pei Liu, Mary Beth Nebel, Jennifer M. Gibson, Elyza Kelly, Fantao Meng, Christopher A. Cano, Juan M. Pascual, Stewart H. Mostofsky, Jason P. Lerch & Peter T. Tsai. Nature.

The Right Crus I (RCrusI) of the cerebellum is thought to play a role in autism spectrum disorders (ASD). Here they combine neuroimaging and neuromodulation in both human and animal models of autism, and most notably they rescued social behaviors in an ASD mouse model, further confirming the cerebellum as a therapeutic target.

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9. The central amygdala controls learning in the lateral amygdala by Kai Yu, Sandra Ahrens, Xian Zhang, Hillary Schiff, Charu Ramakrishnan, Lief Fenno, Karl Deisseroth, Fei Zhao, Min-Hua Luo, Ling Gong, Miao He, Pengcheng Zhou, Liam Paninski & Bo Li. Nature Neuroscience.

Using nVista Ca2+ imaging in freely behaving mice, they show that PKC-δ-expressing central amygdala neurons convey information about the unconditioned stimulus to lateral amygdala neurons during fear conditioning.

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10. Concerted interneuron activity in the cerebellar molecular layer during rhythmic oromotor behaviors by G. Astorga, D. Li, L. Therreau, M. Kassa, A. Marty and I. Llano. Journal of Neuroscience.

They used two-photon GCaMP6s imaging of individual molecular layer interneurons (MLIs) in the Crus II region of awake female mice during two types of oromotor activity, licking and bruxing. They see stellate and basket cells engage in synchronized, correlated waves of calcium activity during licking and bruxing.

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11. Optogenetic inhibition reveals distinct roles for basolateral amygdala activity at discrete timepoints during risky decision making by Caitlin A. Orsini, Caesar M. Hernandez, Sarthak Singhal, Kyle B. Kelly, Charles J. Frazier, Jennifer L. Bizon and Barry Setlow. Journal of Neuroscience.

They used optogenetics to inhibit the BLA during specific task phases in a model of risky decision making in which rats chose between a small, “safe” reward and a large reward accompanied by varying probabilities of footshock punishment. They found that the BLA can either inhibit or promote choice of risky options, depending on the phase of the decision process in which it is active.

Read more here

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