scholarly journals Differential Effects of Open- and Closed-Loop Intracortical Microstimulation on Firing Patterns of Neurons in Distant Cortical Areas

2019 ◽  
Vol 30 (5) ◽  
pp. 2879-2896 ◽  
Author(s):  
Alberto Averna ◽  
Valentina Pasquale ◽  
Maxwell D Murphy ◽  
Maria Piera Rogantin ◽  
Gustaf M Van Acker ◽  
...  
Keyword(s):  
Closed Loop ◽  
Activity Patterns ◽  
Brain Lesion ◽  
Progressive Increase ◽  
Intracortical Microstimulation ◽  
Behavioral Recovery ◽  
Firing Patterns ◽  
Electrical Microstimulation ◽  
Spike Patterns ◽  
Activity Dependent

Abstract Intracortical microstimulation can be used successfully to modulate neuronal activity. Activity-dependent stimulation (ADS), in which action potentials recorded extracellularly from a single neuron are used to trigger stimulation at another cortical location (closed-loop), is an effective treatment for behavioral recovery after brain lesion, but the related neurophysiological changes are still not clear. Here, we investigated the ability of ADS and random stimulation (RS) to alter firing patterns of distant cortical locations. We recorded 591 neuronal units from 23 Long-Evan healthy anesthetized rats. Stimulation was delivered to either forelimb or barrel field somatosensory cortex, using either RS or ADS triggered from spikes recorded in the rostral forelimb area (RFA). Both RS and ADS stimulation protocols rapidly altered spike firing within RFA compared with no stimulation. We observed increase in firing rates and change of spike patterns. ADS was more effective than RS in increasing evoked spikes during the stimulation periods, by producing a reliable, progressive increase in stimulus-related activity over time and an increased coupling of the trigger channel with the network. These results are critical for understanding the efficacy of closed-loop electrical microstimulation protocols in altering activity patterns in interconnected brain networks, thus modulating cortical state and functional connectivity.

scholarly journals Differential effects of open- and closed-loop intracortical microstimulation on firing patterns of neurons in distant cortical areas

2019 ◽  
Author(s):  
Alberto Averna ◽  
Valentina Pasquale ◽  
Maxwell Murphy ◽  
Maria Piera Rogantin ◽  
Gustaf Van Acker ◽  
...  
Keyword(s):  
Closed Loop ◽  
Activity Patterns ◽  
Brain Lesion ◽  
Local Variation ◽  
Open Loop ◽  
Intracortical Microstimulation ◽  
Firing Patterns ◽  
Electrical Microstimulation ◽  
Activity Dependent ◽  
Spike Firing

AbstractBackgroundIntracortical microstimulation can be used successfully to modulate neuronal activity. Activity-dependent stimulation (ADS), in which action potentials recorded extracellularly from a single neuron are used to trigger stimulation at another cortical location (closed-loop), is an effective treatment for behavioral recovery after brain lesion in rodents. Neurophysiological changes in cortical communication induced by ADS, and how these changes differ from those induced by open-loop random stimulation (RS) are still not clear.ObjectivesWe investigated the ability of ADS and RS to induce changes in firing patterns in distant populations of neurons in healthy anesthetized rats.MethodsFor this study we used 23 adult Long-Evan rats, recording from a total of 591 neuronal units. Stimulation was delivered to either forelimb or barrel field somatosensory cortex, using either randomly-timed stimulus pulses or ADS triggered from neuronal spikes recorded in the rostral forelimb area (RFA) of the motor cortex.ResultsBoth RS and ADS stimulation protocols rapidly altered spike firing within RFA compared with no stimulation. Changes consisted of increases in mean firing rates and patterns of spike firing as measured by the revised Local Variation metric. ADS was more effective than RS in increasing short-latency evoked spikes during the stimulation periods, by producing a reliable, progressive increase in stimulus-related activity over time.ConclusionsThese results are critical for understanding the efficacy of electrical microstimulation protocols in altering activity patterns in interconnected brain networks. These data further strengthen the idea that activity-dependent microstimulation, can be used to modulate cortical state and functional connectivity.

scholarly journals Differential impact of mitochondrial positioning on mitochondrial Ca2+ uptake and Ca2+ spark suppression in skeletal muscle

2011 ◽  
Vol 301 (5) ◽  
pp. C1128-C1139 ◽  
Author(s):  
Ann E. Rossi ◽  
Simona Boncompagni ◽  
Lan Wei ◽  
Feliciano Protasi ◽  
Robert T. Dirksen
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Osmotic Shock ◽  
Progressive Increase ◽  
Tetanic Stimulation ◽  
Differential Impact ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum ◽  
Activity Dependent ◽  
Old Mice

Muscle contraction requires ATP and Ca2+ and, thus, is under direct control of mitochondria and the sarcoplasmic reticulum. During postnatal skeletal muscle maturation, the mitochondrial network exhibits a shift from a longitudinal (“longitudinal mitochondria”) to a mostly transversal orientation as a result of a progressive increase in mitochondrial association with Ca2+ release units (CRUs) or triads (“triadic mitochondria”). To determine the physiological implications of this shift in mitochondrial disposition, we used confocal microscopy to monitor activity-dependent changes in myoplasmic (fluo 4) and mitochondrial (rhod 2) Ca2+ in single flexor digitorum brevis (FDB) fibers from 1- to 4-mo-old mice. A robust and sustained Ca2+ accumulation in triadic mitochondria was triggered by repetitive tetanic stimulation (500 ms, 100 Hz, every 2.5 s) in FDB fibers from 4-mo-old mice. Specifically, mitochondrial rhod 2 fluorescence increased 272 ± 39% after a single tetanus and 412 ± 45% after five tetani and decayed slowly over 10 min following the final tetanus. Similar results were observed in fibers expressing mitochondrial pericam, a mitochondrial-targeted ratiometric Ca2+ indicator. Interestingly, sustained mitochondrial Ca2+ uptake following repetitive tetanic stimulation was similar for triadic and longitudinal mitochondria in FDB fibers from 1-mo-old mice, and both mitochondrial populations were found by electron microscopy to be continuous and structurally tethered to the sarcoplasmic reticulum. Conversely, the frequency of osmotic shock-induced Ca2+ sparks per CRU density decreased threefold (from 3.6 ± 0.2 to 1.2 ± 0.1 events·CRU−1·min−1·100 μm−2) during postnatal development in direct linear correspondence ( r2 = 0.95) to an increase in mitochondrion-CRU pairing. Together, these results indicate that mitochondrion-CRU association promotes Ca2+ spark suppression but does not significantly impact mitochondrial Ca2+ uptake.

scholarly journals Coupling an aVLSI Neuromorphic Vision Chip to a Neurotrophic Model of Synaptic Plasticity: The Development of Topography

2002 ◽  
Vol 14 (10) ◽  
pp. 2353-2370 ◽  
Author(s):  
Terry Elliott ◽  
Jörg Kramer
Keyword(s):  
Synaptic Plasticity ◽  
Neuronal Development ◽  
Ganglion Cells ◽  
Activity Patterns ◽  
Retinal Ganglion ◽  
Biologically Inspired ◽  
Silicon Neurons ◽  
Retina Chip ◽  
Developing System ◽  
Activity Dependent

We couple a previously studied, biologically inspired neurotrophic model of activity-dependent competitive synaptic plasticity and neuronal development to a neuromorphic retina chip. Using this system, we examine the development and refinement of a topographic mapping between an array of afferent neurons (the retinal ganglion cells) and an array of target neurons. We find that the plasticity model can indeed drive topographic refinement in the presence of afferent activity patterns generated by a real-world device. We examine the resilience of the developing system to the presence of high levels of noise by adjusting the spontaneous firing rate of the silicon neurons.

Intrinsic Properties Shape the Firing Pattern of Ventral Horn Interneurons From the Spinal Cord of the Adult Turtle

2006 ◽  
Vol 96 (5) ◽  
pp. 2670-2677 ◽  
Author(s):  
Morten Smith ◽  
Jean-François Perrier
Keyword(s):  
Spinal Cord ◽  
Activity Patterns ◽  
Ventral Horn ◽  
Inward Rectification ◽  
Intrinsic Properties ◽  
Patch Clamp Technique ◽  
Firing Patterns ◽  
Pharmacological Tests ◽  
Low Threshold

Interneurons in the ventral horn of the spinal cord play a central role in motor control. In adult vertebrates, their intrinsic properties are poorly described because of the lack of in vitro preparations from the spinal cord of mature mammals. Taking advantage of the high resistance to anoxia in the adult turtle, we used a slice preparation from the spinal cord. We used the whole cell blind patch-clamp technique to record from ventral horn interneurons. We characterized their firing patterns in response to depolarizing current pulses and found that all the interneurons fired repetitively. They displayed bursting, adapting, delayed, accelerating, or oscillating firing patterns. By combining electrophysiological and pharmacological tests, we showed that interneurons expressed slow inward rectification, plateau potential, voltage-sensitive transient outward rectification, and low-threshold spikes. These results demonstrate a diversity of intrinsic properties that may enable a rich repertoire of activity patterns in the network of ventral horn interneurons.

Enhancement of synaptic facilitation during the progression of kindling epilepsy by amygdala stimulations

1993 ◽  
Vol 70 (2) ◽  
pp. 602-609 ◽  
Author(s):  
S. Matsuura ◽  
K. Hirayama ◽  
R. Murata
Keyword(s):  
Quantitative Analysis ◽  
Long Term Potentiation ◽  
Progressive Increase ◽  
Friedman Test ◽  
Single Test ◽  
Term Potentiation ◽  
Excitatory Component ◽  
Activity Dependent ◽  
Excitatory Potential

1. A quantitative analysis of facilitation during the kindling stimulation to the amygdala was conducted by measuring the area between the excitatory potential and the baseline in the averaged tetanic response recorded at the entorhinal cortex. The changes in facilitation were then compared with the development of electrographic afterdischarges (AD) and behavioral seizures in response to successive kindling stimulations. 2. Kindling train pulses (n = 99 or 100; duration: 0.5 ms; frequency: 10 Hz; intensity: AD threshold) were applied to conscious rats until at least one generalized seizure occurred or until 13 stimuli were delivered. 3. Facilitation of the entorhinal responses by kindling stimulation first occurred in the monosynaptic excitatory component and was then followed by a progressive increase in the polysynaptic component that was manifested as the later negative peaks. A clear progressive enhancement was observed in the facilitation by successive kindling stimulations, which also induced prolongation of the AD duration and progression of the seizure stages, indicating that activity-dependent enhancement of facilitation (EF) occurred during the progression of kindling epilepsy. 4. Quantitative analysis revealed that the EF that occurred with the progression of seizure stages was statistically significant (P < 0.001, Friedman test). The AD duration (r = 0.89) and the long-term potentiation (r = 0.85) of the entorhinal responses by single test amygdala stimuli showed a very good linear relation to the EF.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Superresolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity

2017 ◽  
Vol 114 (6) ◽  
pp. 1401-1406 ◽  
Author(s):  
Ronan Chéreau ◽  
G. Ezequiel Saraceno ◽  
Julie Angibaud ◽  
Daniel Cattaert ◽  
U. Valentin Nägerl
Keyword(s):  
Conduction Velocity ◽  
High Frequency ◽  
Information Transfer ◽  
Brain Slices ◽  
Morphological Plasticity ◽  
Time Lapse ◽  
Progressive Increase ◽  
Fine Tuning ◽  
Synaptic Boutons ◽  
Activity Dependent

Axons convey information to nearby and distant cells, and the time it takes for action potentials (APs) to reach their targets governs the timing of information transfer in neural circuits. In the unmyelinated axons of hippocampus, the conduction speed of APs depends crucially on axon diameters, which vary widely. However, it is not known whether axon diameters are dynamic and regulated by activity-dependent mechanisms. Using time-lapse superresolution microscopy in brain slices, we report that axons grow wider after high-frequency AP firing: synaptic boutons undergo a rapid enlargement, which is mostly transient, whereas axon shafts show a more delayed and progressive increase in diameter. Simulations of AP propagation incorporating these morphological dynamics predicted bidirectional effects on AP conduction speed. The predictions were confirmed by electrophysiological experiments, revealing a phase of slowed down AP conduction, which is linked to the transient enlargement of the synaptic boutons, followed by a sustained increase in conduction speed that accompanies the axon shaft widening induced by high-frequency AP firing. Taken together, our study outlines a morphological plasticity mechanism for dynamically fine-tuning AP conduction velocity, which potentially has wide implications for the temporal transfer of information in the brain.

scholarly journals GluA4 subunit of AMPA receptors mediates the early synaptic response to altered network activity in the developing hippocampus

2016 ◽  
Vol 115 (6) ◽  
pp. 2989-2996 ◽  
Author(s):  
J. Huupponen ◽  
T. Atanasova ◽  
T. Taira ◽  
S. E. Lauri
Keyword(s):  
Ampa Receptors ◽  
Pyramidal Neurons ◽  
Activity Patterns ◽  
Critical Role ◽  
Long Term Potentiation ◽  
Postnatal Period ◽  
Homeostatic Plasticity ◽  
Network Activity ◽  
Hippocampal Pyramidal Neurons ◽  
Activity Dependent

Development of the neuronal circuitry involves both Hebbian and homeostatic plasticity mechanisms that orchestrate activity-dependent refinement of the synaptic connectivity. AMPA receptor subunit GluA4 is expressed in hippocampal pyramidal neurons during early postnatal period and is critical for neonatal long-term potentiation; however, its role in homeostatic plasticity is unknown. Here we show that GluA4-dependent plasticity mechanisms allow immature synapses to promptly respond to alterations in network activity. In the neonatal CA3, the threshold for homeostatic plasticity is low, and a 15-h activity blockage with tetrodotoxin triggers homeostatic upregulation of glutamatergic transmission. On the other hand, attenuation of the correlated high-frequency bursting in the CA3-CA1 circuitry leads to weakening of AMPA transmission in CA1, thus reflecting a critical role for Hebbian synapse induction in the developing CA3-CA1. Both of these developmentally restricted forms of plasticity were absent in GluA4 −/− mice. These data suggest that GluA4 enables efficient homeostatic upscaling and responsiveness to temporal activity patterns during the critical period of activity-dependent refinement of the circuitry.

scholarly journals Activity-dependent inhibitory synapse remodeling through gephyrin phosphorylation

2014 ◽  
Vol 112 (1) ◽  
pp. E65-E72 ◽  
Author(s):  
Carmen E. Flores ◽  
Irina Nikonenko ◽  
Pablo Mendez ◽  
Jean-Marc Fritschy ◽  
Shiva K. Tyagarajan ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Phosphorylation Site ◽  
Morphological Plasticity ◽  
Long Term Potentiation ◽  
Inhibitory Synapse ◽  
Inhibitory Synapses ◽  
Synapse Plasticity ◽  
Inhibitory Plasticity ◽  
And Function ◽  
Activity Dependent

Maintaining a proper balance between excitation and inhibition is essential for the functioning of neuronal networks. However, little is known about the mechanisms through which excitatory activity can affect inhibitory synapse plasticity. Here we used tagged gephyrin, one of the main scaffolding proteins of the postsynaptic density at GABAergic synapses, to monitor the activity-dependent adaptation of perisomatic inhibitory synapses over prolonged periods of time in hippocampal slice cultures. We find that learning-related activity patterns known to induce N-methyl-d-aspartate (NMDA) receptor-dependent long-term potentiation and transient optogenetic activation of single neurons induce within hours a robust increase in the formation and size of gephyrin-tagged clusters at inhibitory synapses identified by correlated confocal electron microscopy. This inhibitory morphological plasticity was associated with an increase in spontaneous inhibitory activity but did not require activation of GABAA receptors. Importantly, this activity-dependent inhibitory plasticity was prevented by pharmacological blockade of Ca2+/calmodulin-dependent protein kinase II (CaMKII), it was associated with an increased phosphorylation of gephyrin on a site targeted by CaMKII, and could be prevented or mimicked by gephyrin phospho-mutants for this site. These results reveal a homeostatic mechanism through which activity regulates the dynamics and function of perisomatic inhibitory synapses, and they identify a CaMKII-dependent phosphorylation site on gephyrin as critically important for this process.

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