Neuronal mechanisms underlying the facilitatory control of uropod steering behaviour during treadmill walking in crayfish. I. Antagonistically regulated background excitability of uropod motoneurones

1998 ◽  
Vol 201 (9) ◽  
pp. 1283-1294
Author(s):  
M Murayama ◽  
M Takahata
Keyword(s):  
Motor System ◽  
Membrane Conductance ◽  
Rhythmic Activity ◽  
Synaptic Activity ◽  
Intracellular Recordings ◽  
Sensory Inputs ◽  
Neuronal Mechanisms ◽  
Postural Changes ◽  
To Receive ◽  
Animal Preparation

One of the postural reflexes of crayfish, the uropod steering response, is elicited by specific sensory inputs while the animal is walking. It is not elicited, however, by the same inputs when the animal is at rest. To clarify the neuronal mechanisms underlying this facilitatory control of body posture in the active animals, we used intracellular recordings to analyse the synaptic activities of uropod motor system neurones in an unanaesthetized whole-animal preparation. Several uropod motoneurones were found to receive sustained depolarizing inputs during walking, whereas the walking leg motoneurones sampled always showed rhythmic activity. The membrane conductance of the uropod motoneurones increased during the sustained synaptic activity. Premotor nonspiking interneurones showed depolarizing or hyperpolarizing membrane potential changes during walking that were also accompanied by increases in membrane conductance. Some of these interneurones enhanced uropod motoneurone activity, whereas others suppressed it during walking. These results suggest that the background excitability of uropod motoneurones is kept at an intermediate level during walking by the antagonistic inputs from premotor nonspiking interneurones so that the uropod motor system can be responsive to both further excitatory and inhibitory inputs resulting from postural changes. <P>

Role of chloride-homeostasis in the inhibitory control of neuronal network oscillators

1996 ◽  
Vol 75 (6) ◽  
pp. 2654-2657 ◽  
Author(s):  
W. Jarolimek ◽  
H. Brunner ◽  
A. Lewen ◽  
U. Misgeld
Keyword(s):  
Glycine Receptor ◽  
Membrane Conductance ◽  
Burst Activity ◽  
Synaptic Activity ◽  
Gamma Aminobutyric Acid ◽  
Chloride Homeostasis ◽  
Outward Transport ◽  
Whole Cell Recordings ◽  
Rhythmic Burst

1. Spontaneous synaptic activity in networks formed by dissociated neurons from embryonic rat midbrain was analyzed in tight seal whole cell recordings. 2. Application of furosemide (0.5 mM) to the cell and its surrounding area increased the frequency of spontaneous synaptic currents. Incubation of the culture with furosemide resulted in “rhythmic” burst activity. 3. Furosemide (0.1-0.5 mM) changed equilibrium potentials of inhibitory postsynaptic currents, gamma-aminobutyric acid-A (GABAA) or glycine receptor-mediated Cl- currents by a blockade of Cl(-)-outward transport. Furosemide did not alter the slope conductance of GABAA receptor-mediated currents. Membrane conductance and cell excitability were also unaffected. 4. We conclude that furosemide locked the activity of the network in “burst activity” mode through impairment of inhibition resulting from the disturbance of Cl- homeostasis.

scholarly journals Spinal microcircuits comprising dI3 interneurons are necessary for motor functional recovery following spinal cord transection

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Tuan V Bui ◽  
Nicolas Stifani ◽  
Turgay Akay ◽  
Robert M Brownstone
Keyword(s):  
Spinal Cord ◽  
Functional Recovery ◽  
Motor System ◽  
Motor Training ◽  
Prediction Errors ◽  
Spinal Interneurons ◽  
Motor Activities ◽  
Afferent Inputs ◽  
To Receive ◽  
Sensory Prediction

The spinal cord has the capacity to coordinate motor activities such as locomotion. Following spinal transection, functional activity can be regained, to a degree, following motor training. To identify microcircuits involved in this recovery, we studied a population of mouse spinal interneurons known to receive direct afferent inputs and project to intermediate and ventral regions of the spinal cord. We demonstrate that while dI3 interneurons are not necessary for normal locomotor activity, locomotor circuits rhythmically inhibit them and dI3 interneurons can activate these circuits. Removing dI3 interneurons from spinal microcircuits by eliminating their synaptic transmission left locomotion more or less unchanged, but abolished functional recovery, indicating that dI3 interneurons are a necessary cellular substrate for motor system plasticity following transection. We suggest that dI3 interneurons compare inputs from locomotor circuits with sensory afferent inputs to compute sensory prediction errors that then modify locomotor circuits to effect motor recovery.

Multiple Effects of Serotonin and Acetylcholine on Hyperpolarization-Activated Inward Current in Locomotor Activity-Related Neurons in Cfos-EGFP Mice

2010 ◽  
Vol 104 (1) ◽  
pp. 366-381 ◽  
Author(s):  
Yue Dai ◽  
Larry M. Jordan
Keyword(s):  
Spinal Cord ◽  
Motor System ◽  
Reversal Potential ◽  
Rhythmic Activity ◽  
Maximal Conductance ◽  
Inward Current ◽  
Spinal Interneurons ◽  
Whole Cell Patch Clamp ◽  
Activation Rate ◽  
Maximal Activation

Hyperpolarization-activated inward current ( Ih) has been shown to be involved in production of bursting during various forms of rhythmic activity. However, details of Ih in spinal interneurons related to locomotion remain unknown. Using Cfos-EGFP transgenic mice (P6–P12) we are able to target the spinal interneurons activated by locomotion. Following a locomotor task, whole cell patch-clamp recordings were obtained from ventral EGFP+ neurons in spinal cord slices (T13–L4, 200–250 μm). Ih was found in 51% of EGFP+ neurons ( n = 149) with almost even distribution in lamina VII (51%), VIII (47%), and X (55%). Ih could be blocked by ZD7288 (10–20 μM) or cesium (1–1.5 mM) but was insensitive to barium (2–2.5 mM). Ih activated at −80.1 ± 9.2 mV with half-maximal activation −95.5 ± 13.3 mV, activation rate 10.0 ± 3.2 mV, time constant 745 ± 501 ms, maximal conductance 1.0 ± 0.7 nS, and reversal potential −34.3 ± 3.6 mV. 5-HT (15–20 μM) and ACh (20–30 μM) produced variable effects on Ih. 5-HT increased Ih in 43% of EGFP+ neurons ( n = 37), decreased Ih in 24%, and had no effect on Ih in 33% of the neurons. ACh decreased Ih in 67% of EGFP+ neurons ( n = 18) with unchanged Ih in 33% of the neurons. This study characterizes the Ih in locomotor-related interneurons and is the first to demonstrate the variable effects of 5-HT and ACh on Ih in rodent spinal interneurons. The finding of 5-HT and ACh-induced reduction of Ih in EGFP+ neurons suggests a novel mechanism that the motor system could use to limit the participation of certain neurons in locomotion.

Effect of tetraethylammonium on tonic airway smooth muscle: initiation of phasic electrical activity

1975 ◽  
Vol 228 (2) ◽  
pp. 633-636 ◽  
Author(s):  
EA Kroeger ◽  
NL Stephens
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Electrical Activity ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Mechanical Activity ◽  
Myogenic Response ◽  
Intracellular Recordings ◽  
External Stimulation ◽  
Length Constant

We have previously shown that in the presence of tetraethylammonium (TEA, 6.7-67 mM) phasic mechanical activity and a myogenic response (MR) to quick stretch are produced in normally multi-unit tracheal smooth muscle. The present studies were designed to investigate the electrophysiological basis for these changes in the mechanical properties of the muscle. Intracellular recordings showed that in the presence of TEA the membrane was partially depolarized and trains of small (8-20 mV), decrementally conducted action potentials were produced spontaneously at a frequency of 15-20/min. Action potentials could also be stimulated by external electrodes, and the conduction velocity over short distances was 0.84 plus or minus 0.2 cm/s. Membrane conductance and rectification, as measured by the magnitude of electrotonic potentials in response to external stimulation, were reduced in the presence of TEA. The length constant was increased from 1.6 plus or minus 0.1 to 2.8 plus or minus 0.2 mm. These results are consistent with the notion that TEA produces phasic membrane electrical activity by reducing P-K.

Membrane Conductance Changes Associated with the Response of Motion Sensitive Insect Visual Neurons

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1222-1224 ◽  
Author(s):  
Cole Gilbert
Keyword(s):  
Direct Evidence ◽  
Membrane Conductance ◽  
Inhibitory Input ◽  
Intracellular Recordings ◽  
Transmembrane Conductance ◽  
Visual Neurons ◽  
Impedance Measurements ◽  
Lobula Plate ◽  
Conductance Changes

Abstract Intracellular recordings and impedance measurements from directionally-selective visual interneurons of the lobula plate of flies show that during motion, transmembrane conductance increases during both depolarizing responses to preferred directions and hyperpolarizing re­sponses to anti-preferred directions. This provides direct evidence that these interneurons are postsynaptic to two separate populations of excitatory and inhibitory input elements.

Nonspiking interneurons in walking system of the cockroach

1975 ◽  
Vol 38 (1) ◽  
pp. 33-52 ◽  
Author(s):  
K. G. Pearson ◽  
C. R. Fourtner
Keyword(s):  
Membrane Potential ◽  
Periplaneta Americana ◽  
Rhythmic Activity ◽  
Synaptic Activity ◽  
Cobalt Sulfide ◽  
Resting Membrane Potential ◽  
Cellular Mechanisms ◽  
Metathoracic Ganglion ◽  
Nonspiking Interneurons ◽  
Leg Movements

Intracellular recordings were made from the neurites of interneurons and motoneurons in the metathoracic ganglion of the cockroach, Periplaneta americana. Many neurons were penetrated which failed to produce action potentials on the application of large depolarizing currents. Nevertheless, some of them strongly excited and/or inhibited slow motoneurons innervating leg musculature, even with weak depolariziing musculature, even with weak depolarizing currents. Cobalt-sulfide-straining of these nonspiking neurons showed them to be interneurons with their neurites contained entirely within the metathoracic ganglion. Two further characteristics of these interneurons were rapid spontaneous fluctuations in membrane potential and a low resting membrane potential. One nonspiking neuron, interneuron I, when depolarized caused a strong excitation of the set of slow levator motoneurons which discharge in bursts during stepping movements of the metathoracic leg. During rhythmic leg movements the membrane potential of interneuron I oscillated with the depolarizing phases occurring at the same time as bursts of activity in the levator motorneurons. No spiking or any other nonspiking neuron was penetrated which could excite these levator motoneurons. From all these observations we conclude that oscillations in the membrane potential of interneuron I are entirely responsible for producing the levator bursts, and thus for producing stepping movements in a walking animal. During rhythmic leg movements, bursts of activity in levator and depressor motoneurons are initiated by slow graded depolarizations. The similarity of the synaptic activity in these two types of motoneurons suggests that burst activity in the depressor motoneurons is also produced by rhythmic activity in nonspiking interneurons. The fact that no spiking neuron was found to excite the depressor motoneurons supports this conclusion. Interneuron I is also an element of the rhythm-generating system, since short depolarizing pulses applied to it during rhythmic activity could reset the thythm. Long-duration current pulses applied to interneuron I in a quiescent animal did not produce rhythmic activity. This observation, together with the finding that during rhythmic activity the slow depolarizations in interneuron I are usually terminated by IPSPs, suggests that interneuron I alone does not generate the rhythm. No spiking interneurons have yet been enccountered which influence the activity in levator motoneurons. Thus, we conclude that the rhythm is generated in a network of nonspiking interneurons. The cellular mechanisms for generating the oscillations in this network are unknown. Continued.

scholarly journals Actions of a Pair of Identified Cerebral-Buccal Interneurons (CBI-8/9) in Aplysia That Contain the Peptide Myomodulin

1999 ◽  
Vol 81 (2) ◽  
pp. 507-520 ◽  
Author(s):  
Yuanpei Xin ◽  
Itay Hurwitz ◽  
Ray Perrins ◽  
Colin G. Evans ◽  
Vera Alexeeva ◽  
...  
Keyword(s):  
Cerebral Ganglion ◽  
Rhythmic Activity ◽  
Excitatory Input ◽  
Small Population ◽  
Inhibitory Input ◽  
Functional Roles ◽  
Buccal Mass ◽  
Strong Contraction ◽  
A Cell ◽  
To Receive

Actions of a pair of identified cerebral-buccal interneurons (CBI-8/9) in Aplysia that contain the peptide myomodulin. A combination of biocytin back-fills of the cerebral-buccal connectives and immunocytochemistry of the cerebral ganglion demonstrated that of the 13 bilateral pairs of cerebral-buccal interneurons in the cerebral ganglion, a subpopulation of 3 are immunopositive for the peptide myomodulin. The present paper describes the properties of two of these cells, which we have termed CBI-8 and CBI-9. CBI-8 and CBI-9 were found to be dye coupled and electrically coupled. The cells have virtually identical properties, and consequently we consider them to be “twin” pairs and refer to them as CBI-8/9. CBI-8/9 were identified by electrophysiological criteria and then labeled with dye. Labeled cells were found to be immunopositive for myomodulin, and, using high pressure liquid chromatography, the cells were shown to contain authentic myomodulin. CBI-8/9 were found to receive synaptic input after mechanical stimulation of the tentacles. They also received excitatory input from C-PR, a neuron involved in neck lengthening, and received a slow inhibitory input from CC5, a cell involved in neck shortening, suggesting that CBI-8/9 may be active during forward movements of the head or buccal mass. Firing of CBI-8 or CBI-9 resulted in the activation of a relatively small number of buccal neurons as evidenced by extracellular recordings from buccal nerves. Firing also produced local movements of the buccal mass, in particular a strong contraction of the I7 muscle, which mediates radula opening. CBI-8/9 were found to produce a slow depolarization and rhythmic activity of B48, the motor neuron for the I7 muscle. The data provide continuing evidence that the small population of cerebral buccal interneurons is composed of neurons that are highly diverse in their functional roles. CBI-8/9 may function as a type of premotor neuron, or perhaps as a peptidergic modulatory neuron, the functions of which are dependent on the coactivity of other neurons.

Cholinergic modulation of the swimmeret motor system in crayfish

1993 ◽  
Vol 70 (6) ◽  
pp. 2391-2398 ◽  
Author(s):  
G. Braun ◽  
B. Mulloney
Keyword(s):  
Motor System ◽  
Motor Pattern ◽  
Rhythmic Activity ◽  
Muscarinic Agonist ◽  
Dependent Manner ◽  
Burst Frequency ◽  
Cholinergic Agonists ◽  
Cholinergic Interneurons ◽  
Dose Dependent ◽  
Esterase Inhibitor

1. The muscarinic agonist pilocarpine induced the swimmeret motor pattern in resting isolated preparations of the crayfish abdominal nerve cord and modulated the burst frequency in a dose-dependent manner. 2. Nicotine did not elicit rhythmic activity in resting isolated preparations but increased the burst frequency in active preparations. Nicotine produced higher burst frequencies than pilocarpine. 3. The acetylcholine (ACh) analogue carbachol combined the effects of pilocarpine and nicotine. It activated isolated resting preparations and increased the burst frequency as effectively as nicotine. The ACh-esterase inhibitor eserine also increased the burst frequency in active preparations. 4. Neither muscarinic nor nicotinic antagonists disrupted the proctolin-induced motor pattern, suggesting that proctolin and cholinergic agonists affect two different pathways for the activation of the swimmeret system. 5. We conclude that cholinergic interneurons participate in initiation of the swimmeret motor pattern and can modulate its burst frequency.

Sign in / Sign up

Export Citation Format

Share Document