Faculty Opinions recommendation of Recurrent connection patterns of corticostriatal pyramidal cells in frontal cortex.

The cortex contains multiple neuron types with specific connectivity and functions. Recent progress has provided a better understanding of the interactions of these neuron types as well as their output organization particularly for the frontal cortex, with implications for the circuit mechanisms underlying cortical oscillations that have cognitive functions. Layer 5 pyramidal cells (PCs) in the frontal cortex comprise two major subtypes: crossed-corticostriatal (CCS) and corticopontine (CPn) cells. Functionally, CCS and CPn cells exhibit similar phase-dependent firing during gamma waves but participate in two distinct subnetworks that are linked unidirectionally from CCS to CPn cells. GABAergic parvalbumin-expressing fast-spiking (PV-FS) cells, necessary for gamma oscillation, innervate PCs, with stronger and global inhibition to somata and weaker and localized inhibitions to dendritic shafts/spines. While PV-FS cells form reciprocal connections with both CCS and CPn cells, the excitation from CPn to PV-FS cells exhibits short-term synaptic dynamics conducive for oscillation induction. The electrical coupling between PV-FS cells facilitates spike synchronization among PV-FS cells receiving common excitatory inputs from local PCs and inhibits other PV-FS cells via electrically communicated spike afterhyperpolarizations. These connectivity characteristics can promote synchronous firing in the local networks of CPn cells and firing of some CCS cells by anode-break excitation. Thus subsets of L5 CCS and CPn cells within different levels of connection hierarchy exhibit coordinated activity via their common connections with PV-FS cells, and the resulting PC output drives diverse neuronal targets in cortical layer 1 and the striatum with specific temporal precision, expanding the computational power of the cortical network.

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Iron Deposition in the Brain Following the Ischemia in a Rat Model of Ischemic Tolerance

Acta Medica (Hradec Kralove Czech Republic) ◽

10.14712/18059694.2018.107 ◽

2004 ◽

Vol 47 (4) ◽

pp. 285-288 ◽

Cited By ~ 1

Author(s):

Viera Danielisová ◽

Miroslava Némethová ◽

Jozef Burda

Keyword(s):

Cerebral Cortex ◽

Frontal Cortex ◽

Rat Model ◽

Pyramidal Neurons ◽

Pyramidal Cells ◽

Ischemic Tolerance ◽

Iron Deposition ◽

Sham Operation ◽

Vessel Occlusion ◽

The Brain

Preconditioning of the brain by short-term ischemia increases brain tolerance to the subsequent severer ischemia. In this study, we investigated iron deposition in the cerebral cortex and the ischemic tolerance in a rat model of cerebral ischemia. Forebrain ischemia was induced by four-vessel occlusion for 5 min as ischemic preconditioning. Two days after preconditioning or after the sham-operation, the second ischemia was induced for 20 min. Changes in the cerebral cortex were examined after 1 to 8 weeks of recirculation following 20 min ischemia with or without preconditioning using the iron histochemistry. Granular deposits of the iron were found in the cytoplasm of the pyramidal cells in the layers III and V of the frontal cortex after 1 week of recirculation. When the rats were exposed to 5 min ischemia 2 days before 20 min lasting ischemia, the deposition of iron in the cytoplasm of the pyramidal cells in layers III and V of the frontal cortex was significantly lower during all periods of reperfusion. Preconditioning 5 min ischemia followed by 2 days of reperfusion before 20 min ischemia also prevented degeneration of the pyramidal neurons in layers III and V of the frontal cortex.

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Selective Cholinergic Modulation of Cortical GABAergic Cell Subtypes

Journal of Neurophysiology ◽

10.1152/jn.1997.78.3.1743 ◽

1997 ◽

Vol 78 (3) ◽

pp. 1743-1747 ◽

Cited By ~ 149

Author(s):

Yasuo Kawaguchi

Keyword(s):

Frontal Cortex ◽

Calcium Binding ◽

Pyramidal Cells ◽

Inhibitory Interneurons ◽

Muscarinic Agonists ◽

Cholinergic Modulation ◽

Morphological Criteria ◽

Cell Recording ◽

Fast Spiking

Kawaguchi, Yasuo. Selective cholinergic modulation of cortical GABAergic cell subtypes. J. Neurophysiol. 78: 1743–1747, 1997. Acetylcholine from the basal forebrain and γ-aminobutyric acid (GABA) from intracortical inhibitory interneurons exert strong influence on the cortical activity and may interact with each other. Cholinergic or muscarinic agonists indeed induced GABAergic postsynaptic currents in pyramidal cells by exciting inhibitory interneurons that have recently been classified into several distinct subtypes on the basis of the physiological, chemical, and morphological criteria. Cholinergic effects on GABAergic cell subtypes were investigated of rat frontal cortex by in vitro whole cell recording with intracellular staining in frontal cortex of young rats. GABAergic cell subtypes were identified physiologically by firing responses to depolarizing current pulses and immunohistochemically as containing parvalbumin, somatostatin, vasoactive intestinal polypeptide (VIP), or cholecystokinin (CCK). Carbachol (10 μM) or (+)-muscarine (3 μM) affected the activities of peptide-containing GABAergic cells with regular- or burst-spiking characteristics, but not of GABAergic cells with fast-spiking characteristics containing the calcium-binding protein parvalbumin orGABAergic cells with late-spiking characteristics. Somatostatin- or VIP-immunoreactive cells were depolarized with spike firing. CCK-immunoreactive cells were affected heterogeneously by cholinergic agonists. Larger CCK cells were hyperpolarized, followed by a slow depolarization, whereas smaller CCK cells were only depolarized. These results suggest that the excitability of cortical GABAergic cell subtypes is differentially regulated by acetylcholine. Differences in cholinergic responses suggest a distinct functional role of each GABAergic cell subtype.

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Reduced firing rates of pyramidal cells in the frontal cortex of APP/PS1 can be restored by acute treatment with levetiracetam

Neurobiology of Aging ◽

10.1016/j.neurobiolaging.2020.08.013 ◽

2020 ◽

Vol 96 ◽

pp. 79-86

Author(s):

Jan L. Klee ◽

Amanda J. Kiliaan ◽

Arto Lipponen ◽

Francesco P. Battaglia

Keyword(s):

Frontal Cortex ◽

Acute Treatment ◽

Pyramidal Cells ◽

Firing Rates

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Ipsi- and contralateral corticocortical projection-dependent subcircuits in layer 2 of the rat frontal cortex

Journal of Neurophysiology ◽

10.1152/jn.00333.2019 ◽

2019 ◽

Vol 122 (4) ◽

pp. 1461-1472 ◽

Cited By ~ 1

Author(s):

Yoshifumi Ueta ◽

Jaerin Sohn ◽

Fransiscus Adrian Agahari ◽

Sanghun Im ◽

Yasuharu Hirai ◽

...

Keyword(s):

Motor Cortex ◽

Frontal Cortex ◽

Pyramidal Cell ◽

Pyramidal Tract ◽

Pyramidal Cells ◽

Cortical Layer ◽

Electrophysiological Properties ◽

Monosynaptic Connection ◽

Layer 2 ◽

Rat Frontal Cortex

In the neocortex, both layer 2/3 and layer 5 contain corticocortical pyramidal cells projecting to other cortices. We previously found that among L5 pyramidal cells of the secondary motor cortex (M2), not only intratelencephalic projection cells but also pyramidal tract cells innervate ipsilateral cortices and that the two subtypes are different in corticocortical projection diversity and axonal laminar distributions. Layer 2/3 houses intratelencephalically projecting pyramidal cells that also innervate multiple ipsilateral and contralateral cortices. However, it remained unclear whether layer 2/3 pyramidal cells can be divided into projection subtypes each with distinct innervation to specific targets. In the present study we show that layer 2 pyramidal cells are organized into subcircuits on the basis of corticocortical projection targets. Layer 2 corticocortical cells of the same projection subtype were monosynaptically connected. Between the contralaterally and ipsilaterally projecting corticocortical cells, the monosynaptic connection was more common from the former to the latter. We also found that ipsilaterally and contralaterally projecting corticocortical cell subtypes differed in their morphological and physiological characteristics. Our results suggest that layer 2 transfers separate outputs from M2 to individual cortices and that its subcircuits are hierarchically organized to form the discrete corticocortical outputs. NEW & NOTEWORTHY Pyramidal cell subtypes and their dependent subcircuits are well characterized in cortical layer 5, but much less is understood for layer 2/3. We demonstrate that in layer 2 of the rat secondary motor cortex, ipsilaterally and contralaterally projecting corticocortical cells are largely segregated. These layer 2 cell subtypes differ in dendrite morphological and intrinsic electrophysiological properties, and form subtype-dependent connections. Our results suggest that layer 2 pyramidal cells form distinct subcircuits to provide discrete corticocortical outputs.

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