"Balanced feedforward inhibition and dominant recurrent inhibition in olfactory cortex"
AM Large, NW Vogler, S Mielo and A-MM Oswald
Proc Natl Acad Sci U S A. 113(8):2276-81
We investigated the relationship between excitation and inhibition onto the three main classes of excitatory neuron in the anterior piriform cortex. Our main finding is that all cell types receive balanced feedforward excitation and inhibition while recurrent inhibition is much stronger than excitation. We also found that superficial L2 neurons (semilunar and pyramidal cells) receive less overall inhibition that deep L3 pyramidal cells. But L2 neurons receive more reliable feedforward inputs than L3 neurons. This suggests that these groups of neurons make different contributions to afferent versus recurrent network processing of odor information.
Inhibition by somatostatin interneurons in olfactory cortex
AM Large, NA Kunz, S Mielo and A-MM Oswald
Frontiers Neural Circuits 17 August 2016, http://dx.doi.org/10.3389/fncir.2016.00062
In this study we characterized the spatial distributions of somatostatin and parvalbumin expressing interneurons in anterior piriform cortex in SST-cre, GIN, PV-cre and G42 mouse lines. The interneuron distributions were similar to previous immunochemistry studies in SST-cre and PV-cre lines. However, unlike neocortical areas, labeled interneurons in the GIN (SST) and G42 (PV) lines were nearly absent in piriform cortex. Next we characterized the electrophysiological properties of SST interneurons and found a large proportion were fast-spiking and very similar to PV interneurons. When we optogenetically activated SST-cells, we recorded IPSCs in the majority of L3 interneurons including SST-cells. PV cells appear to receive the strongest inhibition of the interneuron classes. Finally we show that pyramidal cells receive both dendritic and perisomatic inhibition from SST-cells.
Differential inhibition of pyramidal cells and inhibitory interneurons along the rostrocaudal axis of anterior piriform cortex
AM Large, NW Vogler, M Canto-Bustos, FK Friason, P Shick, and A-MM Oswald
Proc Natl Acad Sci August 21, 2018, 115 (34) E8067-E8076
The spatial mapping of sensory features has proven useful in elucidating circuit mechanisms that underlie sensory representations in the brain. The piriform cortex is postulated to play a prominent role in the formation of odor percepts but lacks a topographic representation for odor information. We show spatial patterning of inhibition along the rostrocaudal axis of piriform cortex that differs with respect to excitatory and inhibitory neurons. The underlying inhibitory circuits differ in rostral vs. caudal piriform cortex- particularly for inhibition mediated by somatostatin expressing interneurons. This rostrocaudal spatial organization could provide a scaffold for investigating circuit computations during odor processing.
AM Large, NW Vogler, S Mielo and A-MM Oswald
Proc Natl Acad Sci U S A. 113(8):2276-81
We investigated the relationship between excitation and inhibition onto the three main classes of excitatory neuron in the anterior piriform cortex. Our main finding is that all cell types receive balanced feedforward excitation and inhibition while recurrent inhibition is much stronger than excitation. We also found that superficial L2 neurons (semilunar and pyramidal cells) receive less overall inhibition that deep L3 pyramidal cells. But L2 neurons receive more reliable feedforward inputs than L3 neurons. This suggests that these groups of neurons make different contributions to afferent versus recurrent network processing of odor information.
Inhibition by somatostatin interneurons in olfactory cortex
AM Large, NA Kunz, S Mielo and A-MM Oswald
Frontiers Neural Circuits 17 August 2016, http://dx.doi.org/10.3389/fncir.2016.00062
In this study we characterized the spatial distributions of somatostatin and parvalbumin expressing interneurons in anterior piriform cortex in SST-cre, GIN, PV-cre and G42 mouse lines. The interneuron distributions were similar to previous immunochemistry studies in SST-cre and PV-cre lines. However, unlike neocortical areas, labeled interneurons in the GIN (SST) and G42 (PV) lines were nearly absent in piriform cortex. Next we characterized the electrophysiological properties of SST interneurons and found a large proportion were fast-spiking and very similar to PV interneurons. When we optogenetically activated SST-cells, we recorded IPSCs in the majority of L3 interneurons including SST-cells. PV cells appear to receive the strongest inhibition of the interneuron classes. Finally we show that pyramidal cells receive both dendritic and perisomatic inhibition from SST-cells.
Differential inhibition of pyramidal cells and inhibitory interneurons along the rostrocaudal axis of anterior piriform cortex
AM Large, NW Vogler, M Canto-Bustos, FK Friason, P Shick, and A-MM Oswald
Proc Natl Acad Sci August 21, 2018, 115 (34) E8067-E8076
The spatial mapping of sensory features has proven useful in elucidating circuit mechanisms that underlie sensory representations in the brain. The piriform cortex is postulated to play a prominent role in the formation of odor percepts but lacks a topographic representation for odor information. We show spatial patterning of inhibition along the rostrocaudal axis of piriform cortex that differs with respect to excitatory and inhibitory neurons. The underlying inhibitory circuits differ in rostral vs. caudal piriform cortex- particularly for inhibition mediated by somatostatin expressing interneurons. This rostrocaudal spatial organization could provide a scaffold for investigating circuit computations during odor processing.