Optophysiological analysis of associational circuits in the olfactory cortex

Hagiwara, Akari; Pal, Sumon K.; Sato, Tomokazu; Wienisch, Martin; Murthy, Venkatesh N.

doi:10.3389/fncir.2012.00018

Cited by 72 publications

(82 citation statements)

References 84 publications

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“…The different responsiveness to THDOC in the anterior and posterior piriform cortices could be due to the weaker interneuron-to-pyramidal cell connections in the anterior compared to the posterior piriform cortex (Luna and Pettit, 2010) and the different patterns of connectivity that characterize these two regions. It is known that the anterior piriform cortex receives sensory information directly from the olfactory tract (Hagiwara et al, 2012), whereas the posterior piriform cortex receives projections from the entorhinal, perihinal, amygdala, prefrontal and anterior piriform regions (Haberly, 2001). The anterior piriform cortex may be thus more sensitive to neurosteroids compared to the posterior piriform cortex due to differential levels of inhibition and different preservation of local networks following slicing (Suzuki and Bekkers, 2011).…”

Section: Thdoc Modulation Of 4ap-induced Interictal and Ictal Activitymentioning

confidence: 99%

Neurosteroids modulate epileptiform activity and associated high-frequency oscillations in the piriform cortex

Herrington

Lévesque

2014

Neuroscience

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Allotetrahydrodeoxycorticosterone (THDOC) belongs to a class of pregnane neurosteroidal compounds that enhance brain inhibition by interacting directly with GABA A signaling, mainly through an increase in tonic inhibitory current. Here, we addressed the role of THDOC in the modulation of interictal-and ictal-like activity and associated high-frequency oscillations (HFOs, 80-500 Hz; ripples: 80-200 Hz, fast ripples: 250-500 Hz) recorded in vitro in the rat piriform cortex, a highly excitable brain structure that is implicated in seizure generation and maintenance. We found that THDOC: (i) increased the duration of interictal discharges in the anterior piriform cortex while decreasing ictal discharge duration in both anterior and posterior piriform cortices; (ii) reduced the occurrence of HFOs associated to both interictal and ictal discharges; and (iii) prolonged the duration of 4-aminopyridine-induced, glutamatergic independent synchronous field potentials that are known to mainly result from the activation of GABA A receptors. Our results indicate that THDOC can modulate epileptiform synchronization in the piriform cortex presumably by potentiating GABA A receptor-mediated signaling. This evidence supports the view that neurosteroids regulate neuronal excitability and thus control the occurrence of seizures.

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Section: Thdoc Modulation Of 4ap-induced Interictal and Ictal Activitymentioning

confidence: 99%

Neurosteroids modulate epileptiform activity and associated high-frequency oscillations in the piriform cortex

Herrington

Lévesque

2014

Neuroscience

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“…In the APC, principal excitatory neuron classes differ in laminar location and in the proportion of afferent vs. intracortical excitatory input received (34)(35)(36)(37). Within L2, semilunar cells (SLCs) receive predominantly afferent excitation, whereas superficial pyramidal cells (sPCs) receive weaker afferent and stronger intracortical excitatory drive.…”

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confidence: 99%

Balanced feedforward inhibition and dominant recurrent inhibition in olfactory cortex

Large

Vogler

Mielo

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Throughout the brain, the recruitment of feedforward and recurrent inhibition shapes neural responses. However, disentangling the relative contributions of these often-overlapping cortical circuits is challenging. The piriform cortex provides an ideal system to address this issue because the interneurons responsible for feedforward and recurrent inhibition are anatomically segregated in layer (L) 1 and L2/3 respectively. Here we use a combination of optical and electrical activation of interneurons to profile the inhibitory input received by three classes of principal excitatory neuron in the anterior piriform cortex. In all classes, we find that L1 interneurons provide weaker inhibition than L2/3 interneurons. Nonetheless, feedforward inhibitory strength covaries with the amount of afferent excitation received by each class of principal neuron. In contrast, intracortical stimulation of L2/3 evokes strong inhibition that dominates recurrent excitation in all classes. Finally, we find that the relative contributions of feedforward and recurrent pathways differ between principal neuron classes. Specifically, L2 neurons receive more reliable afferent drive and less overall inhibition than L3 neurons. Alternatively, L3 neurons receive substantially more intracortical inhibition. These three features-balanced afferent drive, dominant recurrent inhibition, and differential recruitment by afferent vs. intracortical circuits, dependent on cell classsuggest mechanisms for olfactory processing that may extend to other sensory cortices.cortex | inhibition | olfaction

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“…Consistent with previous studies (Haberly 2001; Hagiwara et al. 2012), the FB projection strength of AMPA and NMDA from pPC → aPC was significantly weaker than the FF direction (Fig. 4B–C, a–b ).…”

Section: Resultsmentioning

confidence: 90%

“…Although a recent study by Hagiwara et al. (2012) investigated the associational circuits within the olfactory cortex, it mainly focused on the monosynaptic connections between anterior olfactory nucleus (AON) and PC, and intrinsic connections within PC. Similarly, a study by Luna and Morozov (2012) focused on input-specific excitation of specific neuronal targets within the pPC.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical organization of long-range circuits in the olfactory cortices

Yang

Sun

2015

Physiol Rep

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How sensory information is processed within olfactory cortices is unclear. Here, we examined long-range circuit wiring between different olfactory cortical regions of acute mouse brain slices using a channelrhodopsin-2 (ChR2)-based neuronal targeting approach. Our results provide detailed information regarding the synaptic properties of the reciprocal long-range monosynaptic glutamatergic projections (LRMGP) between and within anterior piriform cortex (aPC), posterior piriform cortex (pPC), and lateral entorhinal cortex (LEC), thereby creating a long-range inter- and intracortical circuit diagrams at the level of synapses and single cortical neurons. Our results reveal the following information regarding hierarchical intra- and intercortical organizations: (i) there is massive bottom-up (i.e., rostral–caudal) excitation within the LRMGP accompanied with strong feedforward (FF) inhibition; (ii) there are convergent FF connections onto LEC from both aPC and pPC; (iii) feedback (FB) intercortical connections are weak with a significant fraction of presumptive silent synapses; and (iv) intra and intercortical long-range connections lack layer specificity and their innervation of interneurons are stronger than neighboring pyramidal neurons. The elucidation of the distinct hierarchical organization of long-range olfactory cortical circuits paves the way for further understanding of higher order cortical processing within the olfactory system.

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Optophysiological analysis of associational circuits in the olfactory cortex

Cited by 72 publications

References 84 publications

Neurosteroids modulate epileptiform activity and associated high-frequency oscillations in the piriform cortex

Neurosteroids modulate epileptiform activity and associated high-frequency oscillations in the piriform cortex

Balanced feedforward inhibition and dominant recurrent inhibition in olfactory cortex

Hierarchical organization of long-range circuits in the olfactory cortices

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