Author response: Embryonic and postnatal neurogenesis produce functionally distinct subclasses of dopaminergic neuron

Brief Sensory Deprivation Triggers Cell Type-Specific Structural and Functional Plasticity in Olfactory Bulb Neurons

“…Previous work from ourselves and others has found that bulbar DA neurons are a heterogeneous population (Chand et al, 2015;Galliano et al, 2018;Korshunov et al, 2020;Kosaka et al, 2019).…”

“…We also corroborated our subjective classification using a quantitative measure of spike onset sharpness: the ratio of errors produced by linear and exponential fits to the peri-threshold portion of the phase plane plot (Baranauskas et al, 2010;Volgushev et al, 2008). Fit error ratios were calculated with a custom Matlab script written by Maxim Volgushev, using variable initial portions of the phase plane plot between voltage threshold and 40% of maximum dV/dt (Baranauskas et al, 2010), for single spikes fired in response to 10 ms current injection at current threshold and up to three subsequent suprathreshold sweeps (Galliano et al, 2018). In M/TC recordings, as expected for large projection neurons with a prominent AIS (Volgushev et al, 2008), these fit error ratios were consistently high (mean ± SEM 5.45 ± 0.58 at 20% maximum dV/dt, n = 35), reflecting their markedly sharp spike onset even in the absence of a clearly biphasic phase plane plot profile.…”

“…In our case this was achieved by unilaterally plugging a nostril for just one day, a minimally-invasive manipulation which effectively mimics the sensory disturbance associated with common respiratory infections, without damaging the olfactory sensory epithelium (Fokkens et al, 2012). We found that such brief sensory deprivation produced structural and functional intrinsic plasticity in axon-bearing dopaminergic (DA) neurons in the bulb's glomerular layer (Chand et al, 2015;Galliano et al, 2018). By targeting excitability in one specialised dopaminergic subpopulation, experience-dependent plasticity in early olfactory networks might act to fine-tune sensory processing in the face of continually fluctuating inputs.…”

A Systematic Framework for Olfactory Bulb Signal Transformations

“…Subsequent experimental work, however, made it clear that short-axon cells are in fact inhibitory interneurons, expressing GABA and dopamine (Banerjee et al, 2015), in this resembling the GAD67-expressing subtype of periglomerular cells (Kiyokage et al, 2010) [Indeed, the multimodal diversity of GABAexpressing interneurons in MOB can be interpreted as a single, distinctly heterogeneous cell group encompassing both the (traditionally defined) periglomerular and short-axon cell types (Sethupathy et al, 2013), though more recent findings indicate a more categorical distinction between presumptive short-axon cells and the remaining diversity of periglomerular cells (Galliano et al, 2018)]. These Banerjee et al findings entirely superseded the Cleland et al model predicated on excitatory lateral projections.…”

“…In particular, being based on inhibition, it is more intrinsically stable, and in principle may exhibit a greater capacity to distribute inhibition selectively onto external tufted cells in different MOB columns. That is, in addition to the relational normalization process required for concentration tolerance, there also may be more adaptive, non-uniform transformations, as is suggested by the retention and differentiation of adult-born interneurons in this layer into periglomerular cells (Hack et al, 2005)-though perhaps not short-axon cells (Galliano et al, 2018)-as well as by recent computational modeling work (Zavitz et al, 2020).…”