Spatial profiles of inhibition in piriform cortex. Anne-Marie Oswald Department of Neuroscience, University of Pittsburgh

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1 Spatial profiles of inhibition in piriform cortex Anne-Marie Oswald Department of Neuroscience, University of Pittsburgh

2 Spatial representation of odors Olfactory Bulb Odor Maps Olfactory Bulb Lateral Olfactory Tract (LOT) Nose Wachowiak et al., 2013

3 Non-topographic odor responses in piriform cortex are supported by excitatory circuitry Piriform Cortex OB Axonal projection of a mitral cell APC 1 mm Igarashi et al pinene cadaverine Uniform Intracortical Excitatory Connections APC S1 Butyric Acid Octanol Stettler and Axel, 2009 Franks et al., 2011

4 Distributed cortical activity Sagittal slice of APC TRAP- Targeted recombination in activated neurons during exploration in a novel environment (fos-creer T2 ::tdtom mice) Guenthner et al., 2013

5 Excitation in Piriform Cortex Semilunar (SLC) Superficial Pyramidal (spc) Deep Pyramidal (dpc) LOT L1B L2 L3s L3d Class specific differences intrinsic properties, afferent and intracortical excitation Suzuki and Bekkers 2006,2011, Wiegand et al.,2011

6 Laminar Distributions of Interneuron Classes L1a L1b L2 L3 Feed forward inhibition Strongest excitation from L1a Dendritic L1 interneurons Horizontal and Neurogliaform Feedback/Recurrent inhibition Excitation from L1b, L3 Somatic L2/3 interneurons Parvalbumin (fmp) Somatostatin (rmp) Suzuki and Bekkers, 2010 a,b; 2012

7 Laminar Profile of inhibition L1a Optogenetic activation of interneurons in vgat-chr2 mice L1b L2 L3 L1 L2 L3 Zhao et al, 2011

8 Laminar Profile of inhibition L1a L1b L2 L3 70 µm

9 Laminar Profile of inhibition L1a L1b L2 L3 70 µm ** n=14 interneurons

10 Laminar Profile of inhibition L1a L1b L2 L3s L3d

11 Spatial profile of inhibition in piriform cortex SLCs spcs dpcs Weak inhibition from L1 Strong inhibition from L3 SLCs and spcs receive comparable inhibition dpcs receive strongest inhibition from all layers Inhibition is asymmetric

12 Differential inhibition of SLCs and spcs Semilunar Cell L2 Pyramidal Cell Local (~70 µ diameter)

13 Differential inhibition of SLCs and spcs Semilunar Cell L2 Pyramidal Cell Local (~70 µ diameter) Global (full field)

14 Sources of correlation Shared presynaptic neuron Within trial correlations Noise Correlations Total correlation - signal correlation Simultaneously activated presynaptic pool Across trial correlations Signal Correlations

15 Trial-by-trial correlations in IPSC onsets in SLC-sPC pairs

16 SLCs and spcs receive inhibition from overlapping but distinct interneuron populations

17 Asymmetric spatial profile of Inhibition in APC L2 Pyramidal cells receive more inhibition from caudal stimulation sites Rostral Caudal Luna & Petit, 2010

18 Rostral-caudal inhibitory asymmetry Semilunar Cells L2 Pyramidal Cells L3 Pyramidal Cells

19 Asymmetric inhibition in PCs but not SLCs Semilunar Cells L2 Pyramidal Cells L3 Pyramidal Cells Bias=(<I C >-<I R >) (<I C >+<I R >)

20 Inhibition in Piriform Cortex Semilunar Superficial Pyramidal Deep Pyramidal LOT L1B L2 L3s L3d R C R C Feed forward inhibition weaker than recurrent R SLCs highly distinct patterns of excitation/inhibition spcs and dpcs show comparable patterns but differing magnitudes C

21 How do spatial patterns of inhibition arise? 1) More inhibition in L3 neurons than L2 More interneurons in Layer 3 than in Layers 1 and 2. Interneuron classes in Piriform Cortex L1: 1840 L2: L3: Suzuki and Bekkers, ) Asymmetric inhibition (ongoing) Number of interneurons increase along rostral-caudal axis The strength of unitary inhibitory connections increases along R-C axis Disinhibitory circuitry (See Poster 12)

22 Speculations. LOT L1 cfos Activation Novel Environment Rostral L2 L3 Caudal Superficial to deep activity gradients Rostral-Caudal activity gradients Semilunar cells?

23 Acknowledgements Oswald Lab Adam Large Nathan Vogler Samantha Mielo Collaborators Brent Doiron (UPitt)