Changes in dendritic arborization related to the estrous cycle in pyramidal neurons of layer V of the motor cortex

AbstractDopamine (DA) plays a crucial role in the control of motor and higher cognitive functions such as learning, working memory and decision making. The primary motor cortex (M1), which is essential for motor control and the acquisition of motor skills, receives dopaminergic inputs in its superficial and deep layers from the midbrain. However, the precise action of DA and DA receptor subtypes on the cortical microcircuits of M1 remains poorly understood. The aim of this work was to investigate how DA, through the activation of D2 receptors (D2R), modulates the cellular and synaptic activity of M1 parvalbumin-expressing interneurons (PVINs) which are crucial to regulate the spike output of pyramidal neurons (PNs). By combining immunofluorescence, ex vivo electrophysiology, pharmacology and optogenetics approaches, we show that D2R activation increases neuronal excitability of PVINs and GABAergic synaptic transmission between PVINs and PNs in layer V of M1. Our data reveal a mechanism through which cortical DA modulates M1 microcircuitry and might participate in the acquisition of motor skills.Significance StatementPrimary motor cortex (M1), which is a region essential for motor control and the acquisition of motor skills, receives dopaminergic inputs from the midbrain. However, precise action of dopamine and its receptor subtypes on specific cell types in M1 remained poorly understood. Here, we demonstrate in M1 that dopamine D2 receptors (D2R) are present in parvalbumin interneurons (PVINs) and their activation increases the excitability of the PVINs, which are crucial to regulate the spike output of pyramidal neurons (PNs). Moreover the activation of the D2R facilitates the GABAergic synaptic transmission of those PVINs on layer V PNs. These results highlight how cortical dopamine modulates the functioning of M1 microcircuit which activity is disturbed in hypo- and hyperdopaminergic states.

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Target-specific differences in somatodendritic morphology of layer V pyramidal neurons in rat motor cortex

The Journal of Comparative Neurology ◽

10.1002/cne.20224 ◽

2004 ◽

Vol 476 (2) ◽

pp. 174-185 ◽

Cited By ~ 36

Author(s):

Wen-Jun Gao ◽

Ze-Hui Zheng

Keyword(s):

Motor Cortex ◽

Pyramidal Neurons ◽

Layer V

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Spike Firing and IPSPs in Layer V Pyramidal Neurons during Beta Oscillations in Rat Primary Motor Cortex (M1) In Vitro

PLoS ONE ◽

10.1371/journal.pone.0085109 ◽

2014 ◽

Vol 9 (1) ◽

pp. e85109 ◽

Cited By ~ 16

Author(s):

Michael G. Lacey ◽

Gerard Gooding-Williams ◽

Emma J. Prokic ◽

Naoki Yamawaki ◽

Stephen D. Hall ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Pyramidal Neurons ◽

Beta Oscillations ◽

Layer V ◽

Spike Firing

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Microglia Morphological Changes in the Motor Cortex of hSOD1G93A Transgenic ALS Mice

Brain Sciences ◽

10.3390/brainsci11060807 ◽

2021 ◽

Vol 11 (6) ◽

pp. 807

Author(s):

Sara Migliarini ◽

Silvia Scaricamazza ◽

Cristiana Valle ◽

Alberto Ferri ◽

Massimo Pasqualetti ◽

...

Keyword(s):

Motor Cortex ◽

Motor Neurons ◽

Pyramidal Neurons ◽

Morphological Changes ◽

Double Positive ◽

Spinal Motor Neurons ◽

Progressive Degeneration ◽

Layer V ◽

Als Patients ◽

The Impact

Amyotrophic lateral sclerosis (ALS) is characterized by the progressive degeneration of spinal motor neurons as well as corticospinal (CSN) large pyramidal neurons within cortex layer V. An intense microglia immune response has been associated with both upper and lower motor neuron degeneration in ALS patients, whereas microgliosis occurrence in the motor cortex of hSOD1G93A mice—the best characterized model of this disease—is not clear and remains under debate. Since the impact of microglia cells in the neuronal environment seems to be crucial for both the initiation and the progression of the disease, here we analyzed the motor cortex of hSOD1G93A mice at the onset of symptoms by the immunolabeling of Iba1/TMEM119 double positive cells and confocal microscopy. By means of Sholl analysis, we were able to identify and quantify the presence of presumably activated Iba1/TMEM119-positive microglia cells with shorter and thicker processes as compared to the normal surveilling and more ramified microglia present in WT cortices. We strongly believe that being able to analyze microglia activation in the motor cortex of hSOD1G93A mice is of great importance for defining the timing and the extent of microglia involvement in CSN degeneration and for the identification of the initiation stages of this disease.

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Motor Cortex Layer V Pyramidal Neurons Exhibit Dendritic Regression, Spine Loss, and Increased Synaptic Excitation in the Presymptomatic hSOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis

Journal of Neuroscience ◽

10.1523/jneurosci.3483-14.2015 ◽

2015 ◽

Vol 35 (2) ◽

pp. 643-647 ◽

Cited By ~ 51

Author(s):

Matthew J. Fogarty ◽

Peter G. Noakes ◽

Mark C. Bellingham

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Cortex ◽

Mouse Model ◽

Pyramidal Neurons ◽

Synaptic Excitation ◽

Layer V ◽

Lateral Sclerosis

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Refinement of Active and Passive Membrane Properties of Layer V Pyramidal Neurons in Rat Primary Motor Cortex During Postnatal Development

Frontiers in Molecular Neuroscience ◽

10.3389/fnmol.2021.754393 ◽

2021 ◽

Vol 14 ◽

Author(s):

Patricia Perez-García ◽

Ricardo Pardillo-Díaz ◽

Noelia Geribaldi-Doldán ◽

Ricardo Gómez-Oliva ◽

Samuel Domínguez-García ◽

...

Keyword(s):

Motor Cortex ◽

Postnatal Development ◽

Primary Motor Cortex ◽

Neuronal Excitability ◽

Pyramidal Neurons ◽

Membrane Properties ◽

Neuronal Membrane ◽

Maturation Process ◽

Postnatal Maturation ◽

Layer V

Achieving the distinctive complex behaviors of adult mammals requires the development of a great variety of specialized neural circuits. Although the development of these circuits begins during the embryonic stage, they remain immature at birth, requiring a postnatal maturation process to achieve these complex tasks. Understanding how the neuronal membrane properties and circuits change during development is the first step to understand their transition into efficient ones. Thus, using whole cell patch clamp recordings, we have studied the changes in the electrophysiological properties of layer V pyramidal neurons of the rat primary motor cortex during postnatal development. Among all the parameters studied, only the voltage threshold was established at birth and, although some of the changes occurred mainly during the second postnatal week, other properties such as membrane potential, capacitance, duration of the post-hyperpolarization phase or the maximum firing rate were not defined until the beginning of adulthood. Those modifications lead to a decrease in neuronal excitability and to an increase in the working range in young adult neurons, allowing more sensitive and accurate responses. This maturation process, that involves an increase in neuronal size and changes in ionic conductances, seems to be influenced by the neuronal type and by the task that neurons perform as inferred from the comparison with other pyramidal and motor neuron populations.

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