Austin J. Mendoza

Austin J. Mendoza

PhD candidate // computational modeller of neurons and synaptic networks

Publications

You can also find my articles on my Google Scholar profile.

Cell-specific inhibitory modulation of sound processing in the auditory thalamus

Published in BioRxiv, 2024

Inhibition along the auditory pathway is crucial for processing of acoustic information. Within the auditory thalamus, a key region in the central auditory pathway, inhibition is provided by the thalamic reticular nucleus (TRN), comprised of two large classes of inhibitory neurons, parvalbumin (PVTRN) and somatostatin (SSTTRN) positive. In the auditory cortex, PV and SST neurons differentially shape auditory processing. We found that the ventral MGB, the thalamic region in the direct ascending auditory pathway, receives inputs predominantly from PVTRN neurons, whereas SSTTRN neurons project to the dorso-medial regions of MGB. Consistently, inactivating PVTRN neurons increased sound-evoked activity in over a third of neurons in the vMGB, with another large fraction of neurons being suppressed. By contrast, inactivating SSTTRN neuronal activity largely reduced tone-evoked activity in vMGB neurons. Cell type-specific computational models revealed candidate circuit mechanisms for generating the bi-directional effects of TRN inactivation on MGB sound responses. These differential inhibitory pathways within the auditory thalamus suggest a cell-specific role for thalamic inhibition in auditory computation and behavior.

Recommended citation: S. Rolón-Martínez, A.J. Mendoza, C.F. Angeloni, R. Chen, J.S. Haas, M.N. Geffen. (2024). "Cell-specific inhibitory modulation of sound processing in the auditory thalamus." BioRxiv. DOI: https://www.biorxiv.org/content/10.1101/2024.06.29.601250v1

Intrinsic Sources and Functional Impacts of Asymmetry at Electrical Synapses

Published in eNeuro, 2022

Electrical synapses couple inhibitory neurons across the brain, underlying a variety of functions that are modifiable by activity. Despite recent advances, many functions and contributions of electrical synapses within neural circuitry remain underappreciated. Among these are the sources and impacts of electrical synapse asymmetry. Using multi-compartmental models of neurons coupled through dendritic electrical synapses, we investigated intrinsic factors that contribute to effective synaptic asymmetry and that result in modulation of spike timing and synchrony between coupled cells. We show that electrical synapse location along a dendrite, input resistance, internal dendritic resistance, or directional conduction of the electrical synapse itself each alter asymmetry as measured by coupling between cell somas. Conversely, we note that asymmetrical gap junction (GJ) conductance can be masked by each of these properties. Furthermore, we show that asymmetry modulates spike timing and latency of coupled cells by up to tens of milliseconds, depending on direction of conduction or dendritic location of the electrical synapse. Coordination of rhythmic activity between two cells also depends on asymmetry. These simulations illustrate that causes of asymmetry are diverse, may not be apparent in somatic measurements of electrical coupling, influence dendritic processing, and produce a variety of outcomes on spiking and synchrony of coupled cells. Our findings highlight aspects of electrical synapses that should always be included in experimental demonstrations of coupling, and when assembling simulated networks containing electrical synapses.

Recommended citation: Austin J. mendoza and Julie S. Haas. (2022). "Intrinsic Sources and Functional Impacts of Asymmetry at Electrical Synapses." eNeuro. 9 (2). DOI: https://www.eneuro.org/content/9/2/ENEURO.0469-21.2022