N-methyl-D-aspartate receptor-mediated component of synaptic responses to single-pulse stimulation in rat hippocampal slices

Application of the acetylcholinesterase inhibitor physostigmine to conventional hippocampal slices caused a significant reduction of field excitatory postsynaptic potentials (EPSPs) elicited by single pulse stimulation to the medial perforant path. Similar but smaller effects were obtained in the lateral perforant path and other excitatory pathways within hippocampus. The reductions were blocked by atropine, were not accompanied by evident changes in the EPSP waveform, and were eliminated by lesions to the cholinergic septo-hippocampal projections. Antidromic responses to mossy fiber stimulation, recorded in stratum granulosum, were not affected by the drug. However, paired-pulse facilitation was reliably increased, indicating that the depressed synaptic responses were secondary to reductions in transmitter release. The absence of cholinergic axo-axonic connections in the molecular layer suggests that physostigmine reduces presynaptic release by increasing retrograde signaling from the granule cells. In accord with this, an antagonist of the CB1 cannabinoid receptor eliminated the effects of physostigmine on synaptic responses, while an antagonist of the presynaptically located m2 muscarinic acetylcholine receptor did not. This is in contrast to previously reported effects involving application of cholinergic agonists, in which presynaptic inhibition likely results from direct activation of presynaptically located muscarinic receptors. In summary, it is proposed that the cholinergic inputs from the septum to the middle molecular layer modulate, via endocannabinoid release, the potency of the primary excitatory afferent of hippocampus.

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F154. Machine learning for the analysis of single pulse stimulation in electrocorticography

Clinical Neurophysiology ◽

10.1016/j.clinph.2018.04.317 ◽

2018 ◽

Vol 129 ◽

pp. e125

Author(s):

Emile d’Angremont ◽

Geertjan J. Huiskamp ◽

Frans S. Leijten ◽

Christoph Brune ◽

Michel J. van Putten

Keyword(s):

Machine Learning ◽

Single Pulse ◽

Pulse Stimulation

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Long-term potentiation facilitates behavioral responding to single-pulse stimulation of the perforant path.

Behavioral Neuroscience ◽

10.1037/0735-7044.99.4.603 ◽

1985 ◽

Vol 99 (4) ◽

pp. 603-620 ◽

Cited By ~ 17

Author(s):

Ronald W. Skelton ◽

James J. Miller ◽

Anthony G. Phillips

Keyword(s):

Single Pulse ◽

Long Term Potentiation ◽

Perforant Path ◽

Term Potentiation ◽

Pulse Stimulation ◽

Stimulation Of

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Input-specific maturation of NMDAR-mediated transmission onto parvalbumin-expressing interneurons in layers 2/3 of the visual cortex

Journal of Neurophysiology ◽

10.1152/jn.00495.2018 ◽

2018 ◽

Vol 120 (6) ◽

pp. 3063-3076 ◽

Cited By ~ 4

Author(s):

Camilo Ferrer ◽

Helen Hsieh ◽

Lonnie P. Wollmuth

Keyword(s):

Visual Cortex ◽

Critical Period ◽

Pyramidal Neurons ◽

Temporal Integration ◽

Developmental Changes ◽

Evoked Responses ◽

Developmentally Regulated ◽

Low Frequencies ◽

Aspartate Receptor ◽

Synaptic Responses

Parvalbumin-expressing (PV) GABAergic interneurons regulate local circuit dynamics. In terms of the excitation driving PV interneuron activity, the N-methyl-d-aspartate receptor (NMDAR)-mediated component onto PV interneurons tends to be smaller than that onto pyramidal neurons but makes a significant contribution to their physiology and development. In the visual cortex, PV interneurons mature during the critical period. We hypothesize that during the critical period, the NMDAR-mediated signaling and functional properties of glutamatergic synapses onto PV interneurons are developmentally regulated. We therefore compared the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)- and NMDAR-mediated synaptic responses before (postnatal days 15–20, P15–P20), during (P25–P40), and after (P50–P60) the visual critical period. AMPAR miniature excitatory postsynaptic currents (mEPSCs) showed a developmental decrease in frequency, whereas NMDAR mEPSCs were absent or showed extremely low frequencies throughout development. For evoked responses, we consistently saw a NMDAR-mediated component, suggesting pre- or postsynaptic differences between evoked and spontaneous neurotransmission. Evoked responses showed input-specific developmental changes. For intralaminar inputs, the NMDAR-mediated component significantly decreased with development. This resulted in adult intralaminar inputs almost exclusively mediated by AMPARs, suited for the computation of synaptic inputs with precise timing, and likely having NMDAR-independent forms of plasticity. In contrast, interlaminar inputs maintained a stable NMDAR-mediated component throughout development but had a shift in the AMPAR paired-pulse ratio from depression to facilitation. Adult interlaminar inputs with facilitating AMPAR responses and a substantial NMDAR component would favor temporal integration of synaptic responses and could be modulated by NMDAR-dependent forms of plasticity. NEW & NOTEWORTHY We show for the first time input-specific developmental changes in the N-methyl-d-aspartate receptor component and short-term plasticity of the excitatory drive onto layers 2/3 parvalbumin-expressing (PV) interneurons in the visual cortex during the critical period. These developmental changes would lead to functionally distinct adult intralaminar and interlaminar glutamatergic inputs that would engage PV interneuron-mediated inhibition differently.

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Evaluation of Motor Neuron Excitability by CMAP Scanning with Electric Modulated Current

Neuroscience Journal ◽

10.1155/2015/360648 ◽

2015 ◽

Vol 2015 ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

Tiago Araújo ◽

Rui Candeias ◽

Neuza Nunes ◽

Hugo Gamboa

Keyword(s):

Compound Muscle Action Potential ◽

Single Pulse ◽

Response Amplitude ◽

Stimulus Response ◽

Response Slope ◽

Biphasic Pulse ◽

Muscle Action Potential ◽

Motor Neuron Excitability ◽

Peripheral Nerve Excitability ◽

Pulse Stimulation

Introduction. Compound Muscle Action Potential (CMAP) scan is a noninvasive promissory technique for neurodegenerative pathologies diagnosis. In this work new CMAP scan protocols were implemented to study the influence of electrical pulse waveform on peripheral nerve excitability. Methods. A total of 13 healthy subjects were tested. Stimulation was performed with an increasing intensities range from 4 to 30 mA. The procedure was repeated 4 times per subject, using a different single pulse stimulation waveform: monophasic square and triangular and quadratic and biphasic square. Results. Different waveforms elicit different intensity-response amplitude curves. The square pulse needs less current to generate the same response amplitude regarding the other waves and this effect is gradually decreasing for the triangular, quadratic, and biphasic pulse, respectively. Conclusion. The stimulation waveform has a direct influence on the stimulus-response slope and consequently on the motoneurons excitability. This can be a new prognostic parameter for neurodegenerative disorders.

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Sympatholytic response to stimulation of superior laryngeal nerve in rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1991.260.2.r290 ◽

1991 ◽

Vol 260 (2) ◽

pp. R290-R297 ◽

Cited By ~ 4

Author(s):

D. H. Huangfu ◽

P. G. Guyenet

Keyword(s):

Receptor Antagonist ◽

Superior Laryngeal Nerve ◽

Single Pulse ◽

Laryngeal Nerve ◽

Ventrolateral Medulla ◽

Gamma Aminobutyric Acid ◽

Onset Latency ◽

Medullary Reticular Formation ◽

Pulse Stimulation ◽

Stimulation Of

The central pathway mediating a sympatholytic response to stimulation of the superior laryngeal nerve (SLN) was studied in halothane-anesthetized, paralyzed rats. Single-pulse stimulation of SLN inhibited lumbar sympathetic nerve discharge (LSND) with onset latency of 113 +/- 1.7 ms. LSND inhibition was markedly attenuated by bilateral microinjection of kynurenic acid (Kyn, glutamate receptor antagonist, 4.5 nmol/side) into the caudal ventrolateral medulla (CVL) or by bilateral administration of bicuculline methiodide (Bic; gamma-aminobutyric acid-receptor antagonist, 225 pmol/side) into the rostral ventrolateral medulla (RVL). In 13 of 14 cases, the baroreceptor reflex was also severely reduced. Injections of Bic or Kyn elsewhere in the medullary reticular formation were ineffective. Single-pulse stimulation of SLN inhibited 19 of 26 RVL reticulospinal barosensitive cells (onset latency 46 +/- 1.4 ms). This inhibition was attenuated (from 92 +/- 6 to 14 +/- 12%) by iontophoretic application of Bic (n = 7), which also reduced the cells' inhibitory response to aortic coarctation. The remaining seven barosensitive neurons were unaffected by SLN stimulation. In conclusion, the sympathetic baroreflex and the sympathoinhibitory response to SLN stimulation appear to be mediated by similar medullary pathways.

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Respiratory motor responses to cranial nerve afferent stimulation in rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1996.271.4.r1054 ◽

1996 ◽

Vol 271 (4) ◽

pp. R1054-R1062 ◽

Cited By ~ 4

Author(s):

F. Hayashi ◽

D. R. McCrimmon

Keyword(s):

Cranial Nerve ◽

Superior Laryngeal Nerve ◽

Single Pulse ◽

Short Latency ◽

Lung Inflation ◽

Dorsal Respiratory Group ◽

Inspiratory Activity ◽

Pharyngeal Branch ◽

Pulse Stimulation ◽

Stimulation Of

It was hypothesized that, because rats appear to lack a prominent disynaptic projection from the dorsal respiratory group to phrenic motoneurons (Phr), they would lack the short-latency excitation of Phr output seen in cats in response to stimulation of some cranial nerve afferents. Single-pulse superior laryngeal nerve (SLN) stimulation elicited a short-latency bilateral excitation of glossopharyngeal (IX) and hypoglossal (XII) nerves and an ipsilateral excitation of pharyngeal branch of vagus (PhX) in 67% of rats, but no excitation of Phr. Vagus (X) stimulation elicited a bilateral excitation of Phr and a predominantly ipsilateral excitation of IX and PhX. Single-pulse stimulation of SLN or X also elicited longer-latency, bilateral decreases in activity of all recorded nerves. Repetitive stimulation (50 Hz) of SLN or X suppressed inspiratory activity and prolonged expiration. Lung inflation (7.5 cmH2O) inhibited Phr and PhX activity; X stimulation inhibited Phr but prolonged PhX activity. In conclusion, rats predictably lack the SLN-induced short latency Phr excitation but exhibit other short latency reflexes for which the underlying circuitry is not clear.

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