Every month we pick the must-read research papers of relevance to the circuit neuroscience community. In November, there was again an impressive plethora of papers to peruse across journals, and we highlight 11 of them here. From dopamine circuits in aversion to amygdala → hippocampus circuits in mood, happy reading!
1. Dopamine enhances signal-to-noise ratio in cortical-brainstem encoding of aversive stimuli by Caitlin M. Vander Weele, Cody A. Siciliano, Gillian A. Matthews, Praneeth Namburi, Ehsan M. Izadmehr, Isabella C. Espinel, Edward H. Nieh, Evelien H. S. Schut, Nancy Padilla-Coreano, Anthony Burgos-Robles, Chia-Jung Chang, Eyal Y. Kimchi, Anna Beyeler, Romy Wichmann, Craig P. Wildes & Kay M. Tye. Nature.
They find that dopamine release in the prefrontal cortex modulates the mPFC-dPAG circuit to promote aversive behaviors, particularly under conflict. Dopamine biases behavior towards aversion by increasing signal-to-noise ratio in prefrontal projections to the dPAG. This paper is a most elegant use of Inscopix nVista & nVoke with electrophysiological cross-validation.
2. Hippocampal Place Fields Maintain a Coherent and Flexible Map across Long Timescales by Nathaniel R. Kinsky, David W. Sullivan, William Mau, Michael E. Hasselmo, & Howard B. Eichenbaum. Current Biology.
They use Inscopix nVista calcium imaging in freely behaving mice to evaluate place field dynamics across long timescales.
Read more here
3. A Brainstem-Spinal Circuit Controlling Nocifensive Behavior by Arnab Barik, James Hunter Thompson, Mathew Seltzer, Nima Ghitani, & Alexander T. Chesler. Neuron.
Here they describe and characterize a novel circuit involving a brain stem-spinal cord pathway that selectively controls the nociceptive motor response and dramatically modifies behavior without forebrain involvement.
Read more here and here
4. SYNGAP1 heterozygosity disrupts sensory processing by reducing touch-related activity within somatosensory cortex circuits by Sheldon D. Michaelson, Emin D. Ozkan, Massimiliano Aceti, Sabyasachi Maity, Nerea Llamosas, Monica Weldon, Elisa Mizrachi, Thomas Vaissiere, Michael A. Gaffield, Jason M. Christie, J. Lloyd Holder Jr., Courtney A. Miller & Gavin Rumbaugh. Nature Neuroscience.
They crack some of the circuitry disruptions underlying disease-linked SYNGAP1/Syngap1 variants with impaired sensory processing.
5. An Amygdala-Hippocampus Subnetwork that Encodes Variation in Human Mood by Lowry, A. Kirkby, Francisco J. Luongo, Morgan B. Lee, Mor Nahum, Thomas M. Van Vleet, Vikram R. Rao, Heather E. Dawes, Edward F. Chang, Vikaas S. Sohal. Cell.
Machine learning and intracranial electroencephalography recordings reveal a circuit mechanism encoding mood state fluctuations over time.
6. A Neural Circuit Mechanism for Encoding Aversive Stimuli in the Mesolimbic Dopamine System by Johannes W. de Jong, Seyedeh Atiyeh Afjei, Iskra Pollak Dorocic, James R. Peck, Christine Liu, Christina K. Kim, Lin Tian, Karl Deisseroth, Stephan Lammel. Neuron.
They provide a detailed dissection of the neural circuit architecture of the mesolimbic dopamine (DA) system during appetitive and aversive behaviors. They find, surprisingly, aversive prediction signaling restricted to the vNAcMed and reward prediction signaling in the NAcLat. Furthermore, they demonstrate that LHVGLUT2 neurons represent a key input for providing information about aversive outcomes to vNAcMed-projecting DA neurons.
Read more here
7. Segregated Subnetworks of Intracortical Projection Neurons in Primary Visual Cortex by Mean-Hwan Kim, Petr Znamenskiy, Maria Florencia Iacaruso, Thomas D. Mrsic-Flogel. Neuron.
By examining the local connectivity of V1 neurons projecting to anterolateral (AL) and posteromedial (PM) higher visual areas in mice, they observed that connections between neurons projecting to different targets were rare and significantly less frequent than between those projecting to the same target or randomly sampled neurons.
8. Efficient cortical coding of 3D posture in freely behaving rats by Bartul Mimica, Benjamin A. Dunn, Tuce Tombaz, V. P. T. N. C. Srikanth Bojja, Jonathan R. Whitlock. Science.
They “investigated neuronal representations of body postures in the posterior parietal and frontal motor cortices with three-dimensional tracking of freely moving rodents. Both brain regions represented posture rather than movements and self-motion. Decoding the activity of neurons in the two regions accurately predicted an animal’s posture.”
9. Reward behaviour is regulated by the strength of hippocampus–nucleus accumbens synapses by Tara A. LeGates, Mark D. Kvarta, Jessica R. Tooley, T. Chase Francis, Mary Kay Lobo, Meaghan C. Creed & Scott M. Thompson. Nature.
They showed that “high-frequency activity induces LTP at hippocampus–NAc synapses in mice via canonical, but dopamine-independent, mechanisms. The induction of LTP at this synapse in vivo drives conditioned place preference, and activity at this synapse is required for conditioned place preference in response to a natural reward. Conversely, chronic stress, which induces anhedonia, decreases the strength of this synapse and impairs LTP, whereas antidepressant treatment is accompanied by a reversal of these stress-induced changes.” Thus hippocampus–NAc synapses show activity-dependent plasticity and suggest that their strength may be critical for contextual reward behaviour.
10. Neurochemical and behavioral dissections of decision-making in a rodent multi-stage task by Stephanie M. Groman, Bart Massi, Samuel R. Mathias, Daniel W. Curry, Daeyeol Lee and Jane R. Taylor. Journal of Neuroscience.
They provide the “first evidence that choice behavior in rats is influenced by model-free and model-based systems and demonstrate that model-based, but not model-free, learning is associated with cortico-striatal dopamine tone. This novel behavioral paradigm has the potential to yield critical insights into the mechanisms mediating decision-making alterations in mental disorders.”
Read more here
11. Early Life Stress Drives Sex-Selective Impairment in Reversal Learning by Affecting Parvalbumin Interneurons in Orbitofrontal Cortex of Mice by Haley L. Goodwill, Gabriela Manzano-Nieves, Patrick LaChance, Sana Teramoto, Shirley Lin, Chelsea Lopez, Rachel J. Stevenson, Brian B. Theyel, Christopher I. Moore, Barry W. Connors, Kevin G. Bath. Cell Reports.