Motor cortical control of vocal behaviors in the neotropical singing mouse

Using sounds for social interactions is common across many taxa. Humans engaged in conversation, for example, take rapid turns to go back and forth. This ability to act upon sensory information to generate a desired motor output is a fundamental feature of animal behavior. How the brain enables such flexible sensorimotor transformations, for example during vocal interactions, is a central question in neuroscience. Seeking a rodent model to fill this niche, we are investigating neural mechanisms of vocal interaction in Alston’s singing mouse (Scotinomys teguina) – a neotropical rodent native to the cloud forests of Central America. We discovered sub-second temporal coordination of advertisement songs (counter-singing) between males of this species – a behavior that requires the rapid modification of motor outputs in response to auditory cues. We leveraged this natural behavior to probe the neural mechanisms that generate and allow fast and flexible vocal communication. Using causal manipulations, we recently showed that an orofacial motor cortical area (OMC) in this rodent is required for vocal interactions (Okobi*, Banerjee* et. al, 2019). Subsequently, in electrophysiological recordings, I find neurons in OMC that track initiation, termination and relative timing of songs. Interestingly, persistent neural dynamics during song progression stretches or compresses on every trial to match the total song duration (Banerjee et. al, in preparation). These results demonstrate robust cortical control of vocal timing in a rodent and upends the current dogma that motor cortical control of vocal output is evolutionarily restricted to the primate lineage.

 

D. E. Okobi, Jr*., A. Banerjee*, A. M. M. Matheson, S. M. Phelps, M. A. Long, Motor cortical control of vocal interaction in neotropical singing mice. Science 363, 983-988 (2019).*equal contribution.

 

A. Banerjee, S. M. Phelps, M. A. Long, Singing mice. Curr Biol 29, R190-R191 (2019).

 

Perspective Article on our work (Hage et al, Science. 2019).

Behind the scenes for capturing the cover photo. 
 
Media Coverage: NY Times, Discover magazine, Arstechnica​, Forbes

Gain-control and normalization in the early olfactory system 

For all our senses, the brain must employ mechanisms to ensure perceptual invariance. Simply put, a freshly baked cake should smell like a cake irrespective of whether you are in the kitchen or in the next room. But this is not a trivial task for the brain because the odor concentration decreases substantially the further you go from the odor source. Nevertheless, the cake always smells like a cake. My PhD thesis work characterized the specific neural circuitry behind an important information-processing step in the olfactory system that aids odor discrimination and perceptual invariance.

Banerjee A.*, Marbach F.*, Anselmi F., Koh M., Garcia da Silva P., Davis M.B., Delevich K., Oyibo H., Gupta P., Li B. & Albeanu D.F. (2015). Neuron. 87(1):193-207. PubMed PMID: 26139373. View PDF * equal contribution.

Chae H.G.*, Banerjee A.* & Albeanu D.F. A non-canonical feedforward pathway for computing odor identity. bioRxiv 2020.09.28.317248; Link

Novel technique for simultaneous photo-stimulation and two-photon imaging of neural circuits.

Many neuroscience experiments involve monitoring the response of a system to artificial perturbations. To study how sensory inputs relate to the population output of neurons in the mouse olfactory bulb, we developed a microscopy technique that allows one to photo-stimulate the inputs (glomeruli) while monitoring population neuronal responses using two-photon microscopy. To do so, we use a diffuser in an optical plane conjugated to the sample/imaging plane. The laser light, intensity modulated by a DMD, falls on the diffuser. The intensity-modulated pattern is imaged onto the sample using a telescope. Since the diffuser is optically conjugated with the sample plane, translating the diffuser along the optical axis smoothly de-couples the photo-stimulation plane from the imaging plane.
Anselmi F, Banerjee A & Albeanu D.F. (2015). Springer International Publishing. Switzerland. DOI 10.1007/978-3-319-12913-6_9. View PDF
Society for Neuroscience (SFN, Chicago, 2015)                                                                        
In vivo patterned photo-stimulation and imaging in independent axis planes.                          
Koh, M.S.*, Anselmi, F.*, Banerjee A.*, Davis, M.B., and Albeanu, D.F. * : equal contribution.

Microscopy for visualizing biological phenomenon

Dopamine neurotransmission underlies a variety of functions in the central nervous system including reward processing and movement control. While we can measure the activity of dopaminergic neurons, it has been challenging to measure dopamine in live brain tissue. In my Master’s thesis project, I developed a microscope to directly visualize unlabeled dopamine and measure its dynamics in live brain tissue. This allowed me to image dopamine inside vesicles and measure its dynamics in the substantia nigra of rat brain slices. This method remains the only one to date to directly visualize dopamine in live neurons.
 
Apart from this primary project, I was involved in several others that included developing and using fluorescence spectroscopy methods to measure amyloid beta aggregation, as well as measuring serotonin levels in brain tissue using 3-photon microscopy.

Sarkar B.*, Banerjee A.*, Das A.K., Nag S., Kaushalya S.K., Tripathy U., Shameem M., Shukla S., Maiti S., 2014. Label-free dopamine imaging in live rat brain slices. ACS Chem Neurosci. 5:329-34. * Equal Contribution

Sarkar B., Das A.K., Arumugam S., Kaushalya S.K., Bandyopadhyay A., Balaji J., and Maiti S. 2012. The dynamics of somatic exocytosis in monoaminergic neurons. Front Physiol. 3: 41

Nag S., Sarkar B., Bandyopadhyay A., Sahoo B., Sreenivasan V.K., Kombrabail M., Muralidharan C., and Maiti S. 2011. Nature of the amyloid-beta monomer and the monomer- oligomer equilibrium. J Biol Chem. 286: 13827-13833.

Suman N., Bandyopadhyay A., Sudipta M. 2009. Spatial pH-jump measures chemical kinetics in a steady state system. J. Phys. Chem. 113: 5269-5272.

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