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.

Intracellular recordings from different types of medullary respiratory neurons of the cat

1975 ◽  
Vol 38 (5) ◽  
pp. 1162-1171 ◽  
Author(s):  
D. W. Richter ◽  
F. Heyde ◽  
M. Gabriel
Keyword(s):  
Functional Organization ◽  
Silent Period ◽  
Membrane Conductance ◽  
Rhythmic Activity ◽  
Excitatory Input ◽  
Respiratory Neurons ◽  
Inhibitory Input ◽  
Different Types ◽  
Conductance Changes ◽  
Almost All

Respiratory neurons were recorded intracellularly within the lateral region of the lower brain stem of vagotomized and artificially ventilated cats. Bulbospinal, vagal, and antidromically nonresponsive types of neurons were distinguished by means of vagal and intraspinal stimulation. Almost all types of neurons discharged a burst of action potentials during one of the two phases of the central respiratory cycle, as indicated by phrenic nerve activity. The discharge pattern of the different types of neurons were described. The origin of the spntaneous changes of the membrane potential was investigated by measurements of the reversal potentials and membrane conductance changes. The results reveal that both inspiratory and expiratory types of neurons receive an excitatory input during their discharge period, and a reciprocal inhibitory input during their silent period. In addition, one type of neuron was described which receives inhibitory inputs during both inspiration and expiration. Recurrent inhibition, as indicated by hyperpolarizing postsynaptic potentials and membrane conductance changes following the antidromic action potential seems to exist only within the network of the vagal neurons. Suggestions are made about the functional organization of the neuronal network of the medullary respiratory system and the mechanism generating its rhythmic activity.

C-PR Neuron of Aplysia Has Differential Effects on “Feeding” Cerebral Interneurons, Including Myomodulin-Positive CBI-12

1999 ◽  
Vol 81 (2) ◽  
pp. 521-534 ◽  
Author(s):  
Itay Hurwitz ◽  
Ray Perrins ◽  
Yuanpei Xin ◽  
Klaudiusz R. Weiss ◽  
Irving Kupfermann
Keyword(s):  
Rhythmic Activity ◽  
Excitatory Input ◽  
Small Population ◽  
Plateau Potentials ◽  
Buccal Ganglion ◽  
Feeding Behaviors ◽  
Similar Morphology ◽  
Differential Effects ◽  
Voltage Dependent ◽  
Ingestive Behaviors

C-PR neuron of Aplysia has differential effects on “feeding” cerebral interneurons, including myomodulin-positive CBI-12. Head lifting and other aspects of the appetitive central motive state that precedes consummatory feeding movements in Aplysia is promoted by excitation of the C-PR neuron. Food stimuli activate C-PR as well as a small population of cerebral-buccal interneurons (CBIs). We wished to determine if firing of C-PR produced differential effects on the various CBIs or perhaps affected all the CBIs uniformly as might be expected for a neuron involved in producing a broad undifferentiated arousal state. We found that when C-PR was fired, it produced a wide variety of effects on various CBIs. Firing of C-PR evoked excitatory input to a newly identified CBI (CBI-12) the soma of which is located in the M cluster near the previously identified CBI-2. CBI-12 shares certain properties with CBI-2, including a similar morphology and a capacity to drive rhythmic activity of the buccal-ganglion. Unlike CBI-2, CBI-12 exhibits myomodulin immunoreactivity. Furthermore when C-PR is fired, CBI-12 receives a polysynaptic voltage-dependent slow excitation, whereas, CBI-2 receives relatively little input. C-PR also polysynaptically excites other CBIs including CBI-1 and CBI-8/9 but produces inhibition in CBI-3. In addition, firing of C-PR inhibits plateau potentials in CBI-5/6. The data suggest that activity of C-PR may promote the activity of one subset of cerebral-buccal interneurons, perhaps those involved in ingestive behaviors that occur during the head-up posture. C-PR also inhibits some cerebral-buccal interneurons that may be involved in behaviors in which C-PR activity is not required or may even interfere with other feeding behaviors such as rejection or grazing, that occur with the head down.

scholarly journals Inhibitory Connections Underlying the Directional Sensitivity of the Equilibrium System in the Crayfish Procambarus Clarkii

1990 ◽  
Vol 152 (1) ◽  
pp. 305-312
Author(s):  
H. NAKAGAWA ◽  
M. HISADA
Keyword(s):  
Procambarus Clarkii ◽  
Excitatory Input ◽  
The Other ◽  
Directional Sensitivity ◽  
Inhibitory Input ◽  
Equilibrium System ◽  
Inhibitory Mechanisms ◽  
Neuronal Mechanisms ◽  
To Receive ◽  
The Brain

1. Neuronal mechanisms underlying the directional sensitivity of the crayfish equilibrium system were studied in the brain by intracellular recording combined with mechanical statocyst hair deflection. 2. Five primary afferents were successfully characterized. Three of them showed a decrease in response to inward hair deflection. The remaining two showed the opposite directional response. 3. Directional sensitivity was found in six interneurones. Two of them were excited during inward hair deflection while the other four were excited during outward deflection. Both groups exhibited active inhibition during hair deflections in the opposite direction. 4. This ‘null-phase inhibition’ appeared to arise from the convergence of the two classes of afferents onto an interneurone with the opposite sign. 5. Three identified descending statocyst interneurones, S3, S6 and S7, were found to receive excitatory input from one statocyst and inhibitory input from the other. 6. The results thus indicated that the directional sensitivity of the crayfish equilibrium system was achieved by selective excitatory connections between the interneurone and the directionally arranged receptor and sharpened by inhibitory mechanisms.

scholarly journals Intrinsic Dynamics in Neuronal Networks. I. Theory

2000 ◽  
Vol 83 (2) ◽  
pp. 808-827 ◽  
Author(s):  
P. E. Latham ◽  
B. J. Richmond ◽  
P. G. Nelson ◽  
S. Nirenberg
Keyword(s):  
Firing Rate ◽  
Firing Pattern ◽  
Neuronal Networks ◽  
Network Connectivity ◽  
Excitatory Input ◽  
High Rate ◽  
Inhibitory Neurons ◽  
Inhibitory Input ◽  
Dynamic Interactions ◽  
Firing Patterns

Many networks in the mammalian nervous system remain active in the absence of stimuli. This activity falls into two main patterns: steady firing at low rates and rhythmic bursting. How are these firing patterns generated? Specifically, how do dynamic interactions between excitatory and inhibitory neurons produce these firing patterns, and how do networks switch from one firing pattern to the other? We investigated these questions theoretically by examining the intrinsic dynamics of large networks of neurons. Using both a semianalytic model based on mean firing rate dynamics and simulations with large neuronal networks, we found that the dynamics, and thus the firing patterns, are controlled largely by one parameter, the fraction of endogenously active cells. When no endogenously active cells are present, networks are either silent or fire at a high rate; as the number of endogenously active cells increases, there is a transition to bursting; and, with a further increase, there is a second transition to steady firing at a low rate. A secondary role is played by network connectivity, which determines whether activity occurs at a constant mean firing rate or oscillates around that mean. These conclusions require only conventional assumptions: excitatory input to a neuron increases its firing rate, inhibitory input decreases it, and neurons exhibit spike-frequency adaptation. These conclusions also lead to two experimentally testable predictions: 1) isolated networks that fire at low rates must contain endogenously active cells and 2) a reduction in the fraction of endogenously active cells in such networks must lead to bursting.

Binaural processing of sound pressure level in the inferior colliculus

1987 ◽  
Vol 57 (4) ◽  
pp. 1130-1147 ◽  
Author(s):  
M. N. Semple ◽  
L. M. Kitzes
Keyword(s):  
Inferior Colliculus ◽  
Sound Pressure ◽  
Spatial Information ◽  
Discharge Rate ◽  
Excitatory Input ◽  
Central Nucleus ◽  
Intensity Difference ◽  
Inhibitory Input ◽  
Directional Information ◽  
Discharge Rates

The central auditory system could encode information about the location of a high-frequency sound source by comparing the sound pressure levels at the ears. Two potential computations are the interaural intensity difference (IID) and the average binaural intensity (ABI). In this study of the central nucleus of the inferior colliculus (ICC) of the anesthetized gerbil, we demonstrate that responses of 85% of the 97 single units in our sample were jointly influenced by IID and ABI. For a given ABI, discharge rate of most units is a sigmoidal function of IID, and peak rates occur at IIDs favoring the contralateral ear. Most commonly, successive increments of ABI cause successive shifts of the IID functions toward IIDs favoring the ipsilateral ear. Neurons displaying this behavior include many that would conventionally be classified EI (receiving predominantly excitatory input arising from one ear and inhibitory input from the other), many that would be classified EE (receiving predominantly excitatory input arising from each ear), and all that are responsive only to contralateral stimulation. The IID sensitivity of a very few EI neurons is unaffected by ABI, except near threshold. Such units could provide directional information that is independent of source intensity. A few EE neurons are very sensitive to ABI, but are minimally sensitive to IID. Nevertheless, our data indicate that responses of most EE units in ICC are strongly dominated by excitation of contralateral origin. For some units, discharge rate is nonmonotonically related to IID and is maximal when the stimuli at the two ears are of comparable sound pressure. This preference for zero IID is common for all binaural levels. Many EI neurons respond nonmonotonically to ABI. Discharge rates are greater for IIDs representative of contralateral space and are maximal at a single best ABI. For a subset of these neurons, the influence arising from the ipsilateral ear is comprised of a mixture of excitation and inhibition. As a consequence, discharge rates are nonmonotonically related not only to ABI but also to IID. This dual nonmonotonicity creates a clear focus of peak response at a particular ABI/IID combination. Because of their mixed monaural influences, such units would be ascribed to different classes of the conventional (EE/EI) binaural classification scheme depending on the binaural level presented. Several response classes were identified in this study, and each might contribute differently to the encoding of spatial information.(ABSTRACT TRUNCATED AT 400 WORDS)

Parameter Space Analysis Suggests Multi-Site Plasticity Contributes to Motor Pattern Initiation in Tritonia

2007 ◽  
Vol 98 (4) ◽  
pp. 2382-2398 ◽  
Author(s):  
Robert J. Calin-Jageman ◽  
Mark J. Tunstall ◽  
Brett D. Mensh ◽  
Paul S. Katz ◽  
William N. Frost
Keyword(s):  
Parameter Space ◽  
Large Scale ◽  
Time Course ◽  
Scale Parameter ◽  
Motor Pattern ◽  
Rhythmic Activity ◽  
Excitatory Input ◽  
Space Analysis ◽  
Gastropod Mollusk ◽  
Detailed Simulation

This research examines the mechanisms that initiate rhythmic activity in the episodic central pattern generator (CPG) underlying escape swimming in the gastropod mollusk Tritonia diomedea. Activation of the network is triggered by extrinsic excitatory input but also accompanied by intrinsic neuromodulation and the recruitment of additional excitation into the circuit. To examine how these factors influence circuit activation, a detailed simulation of the unmodulated CPG network was constructed from an extensive set of physiological measurements. In this model, extrinsic input alone is insufficient to initiate rhythmic activity, confirming that additional processes are involved in circuit activation. However, incorporating known neuromodulatory and polysynaptic effects into the model still failed to enable rhythmic activity, suggesting that additional circuit features are also required. To delineate the additional activation requirements, a large-scale parameter-space analysis was conducted (∼2 × 106 configurations). The results suggest that initiation of the swim motor pattern requires substantial reconfiguration at multiple sites within the network, especially to recruit ventral swim interneuron-B (VSI) activity and increase coupling between the dorsal swim interneurons (DSIs) and cerebral neuron 2 (C2) coupling. Within the parameter space examined, we observed a tendency for rhythmic activity to be spontaneous and self-sustaining. This suggests that initiation of episodic rhythmic activity may involve temporarily restructuring a nonrhythmic network into a persistent oscillator. In particular, the time course of neuromodulatory effects may control both activation and termination of rhythmic bursting.

scholarly journals Glutamatergic and GABAergic neuronal populations in the dorsolateral Periacqueductual Gray have different functional roles in fear conditioning

2019 ◽  
Author(s):  
Quentin Montardy ◽  
Zheng Zhou ◽  
Xuemei Liu ◽  
Zhuogui Lei ◽  
Pengyu Zeng ◽  
...  
Keyword(s):  
Fear Conditioning ◽  
Brain Structures ◽  
Aversive Stimulation ◽  
Emotional States ◽  
Functional Roles ◽  
Neuronal Populations ◽  
Defensive Behaviors ◽  
A Cell ◽  
Midbrain Structure ◽  
Virus Tracing

AbstractIt is though that only a subset of brain structures can encode emotional states. This can be investigated though a set of properties, including the ability of neurons to respond to a conditioned stimulus (CS) preceding an aversive unconditioned stimulus (US). The dorsolateral periacqueductal gray (dPAG) is a midbrain structure though to have an essential role in coordinating defensive behaviors in response to aversive stimulation. But its ability of dPAG neurons to encode a CS following fear conditioning as not been sufficiently studied.Here we used calcium imaging by fiber photometry to record the activity of dPAGVGluT2+ and dPAGGAD2+ neuronal populations during unconditioned and conditioned aversive stimulation. Then, following an unconditioned stimulation we performed a retrieval experiment to quantify memory-like responses of dPAG neurons. This shown that whilst both dPAGVGluT2+ and dPAGGAD2+ neuronal populations respond to direct US stimulation, and to CS stimulation during conditioning, only the dPAGVGluT2+ population persisted in responding to the CS stimulation during retrieval. Finally, to better understand dPAGVGluT2+ and dPAGGAD2+ connectivity patterns, we performed a cell specific monosynaptic retrograde rabies virus tracing experiment. This revealed that different patterns of fibers projects to dPAGVGluT2+ and dPAGGAD2+, further complementing our recording showing divergences between PAGVGluT2+ and dPAGGAD2+ populations.

Control of extrinsic feeding muscles in Aplysia

1983 ◽  
Vol 49 (6) ◽  
pp. 1481-1503 ◽  
Author(s):  
B. Jahan-Parwar ◽  
S. M. Fredman
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Synaptic Input ◽  
Cerebral Ganglion ◽  
Cyclic Activity ◽  
Buccal Mass ◽  
Buccal Ganglia ◽  
Identified Neuron ◽  
Single Oscillator ◽  
Extrinsic Muscles

The extrinsic buccal muscles in Aplysia are responsible for the overall protraction and retraction of the buccal mass during feeding. The six pairs of extrinsic muscles are organized into two groups, consisting of three protractors and three retractors. Insights into how the extrinsic muscles are controlled were obtained by examining the organization of the motor neurons that innervated them. The extrinsic buccal muscles are innervated by cerebral ganglion nerves and neurons. All the muscles examined appear to be multiply innervated. Identified neurons in the cerebral B, E, and G clusters were found to be motor neurons for individual extrinsic muscles. Some extrinsic muscles had both excitatory and inhibitory innervation. Two synergistic muscles, the extrinsic ventrolateral protractor (ExVLP) and the extrinsic dorsal protractor (ExDP), had common excitatory innervation by identified neuron E5. Two antagonistic muscles, the ExVLP and the extrinsic ventral retractor (ExVR), also had common innervation. Identified neuron E1 appeared to be an inhibitory motor neuron for the ExVLP but an excitatory motor neuron for the ExVR. Common innervation provides a simple mechanism for coordinating synergistic and antagonistic extrinsic muscles. On the basis of these data, a model for the control of buccal mass protraction and retraction is proposed. Bursting by extrinsic buccal muscles was coordinated with cyclic activity in the intrinsic muscles of the buccal mass. Antagonistic extrinsic muscles burst antiphasically and synergistic extrinsic muscles burst in phase when the buccal mass was fully protracted and exhibited a series of rhythmic contractions. Additionally, cerebral E cluster neurons burst in phase with stereotyped rhythmic buccal motor neuron discharges recorded from buccal nerves. The cerebral E cluster motor neurons were coordinated by common synaptic input. No monosynaptic connections were observed; homologous neurons in each E cluster received synaptic input with similar but not identical timing, indicating that the interneurons that coordinate the homologous motor neurons are synchronized. The source of the rhythm that drives synaptically mediated cerebral extrinsic muscle motor neuron bursting was in the buccal ganglia. Cutting one cerebral-buccal connective eliminated E neuron bursting on that side but had no effect on homologous neurons on the intact side. This suggests that a single oscillator in the buccal ganglia may coordinate both the extrinsic and intrinsic buccal muscles during feeding.

Inhibition Dominates the Early Phase of Up-States in the Basolateral Amygdala

2010 ◽  
Vol 104 (6) ◽  
pp. 3433-3438 ◽  
Author(s):  
Francois Windels ◽  
James W. Crane ◽  
Pankaj Sah
Keyword(s):  
Cortical Neurons ◽  
Basolateral Amygdala ◽  
Feedback Inhibition ◽  
Initial Period ◽  
Excitatory Input ◽  
Resting Membrane Potential ◽  
Inhibitory Input ◽  
Similar Time ◽  
Slow Oscillations ◽  
Up States

Slow oscillations (<1 Hz) in neural activity occur during sleep and quiet wakefulness in both animals and humans. Single-cell recordings in cortical neurons have shown that these oscillations are driven by a combination of excitatory and inhibitory synaptic inputs. During up-states, although the ratio between them varies between cells, excitation and inhibition follow similar time courses. Neurons in the basolateral amygdala (BLA) also show slow oscillations between the resting membrane potential (down-state) and depolarized potentials (up-states). Delivery of footshock during the down-state fully reproduces up-states in these cells. Here we report that up-states in BLA principal neurons up-states begin with an excitatory drive that is rapidly (within ∼50 ms) overwhelmed by inhibitory input. This excess of inhibitory drive is short lasting (300–400 ms), after which up-states are maintained by a tight balance between excitation and inhibition. This initial large inhibitory input restricts action potential generation and reduces the firing frequency of these cells. These results indicate that, in contrast to cortical neurons, up-states in BLA neurons show an initial period of strong cortically driven feed-forward inhibition. For the remainder of the up-state, feedback inhibition then acts to balance excitatory input.

scholarly journals Functional Role of the PE Domain and Immunogenicity of the Mycobacterium tuberculosis Triacylglycerol Hydrolase LipY

2007 ◽  
Vol 76 (1) ◽  
pp. 127-140 ◽  
Author(s):  
Kanhu C. Mishra ◽  
Chantal de Chastellier ◽  
Yeddula Narayana ◽  
Pablo Bifani ◽  
Alistair K. Brown ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Humoral Response ◽  
Host Immune System ◽  
Functional Roles ◽  
Triacylglycerol Hydrolase ◽  
Immunodominant Antigen ◽  
Surface Localization ◽  
A Cell ◽  
First Time

ABSTRACT PE and PPE proteins appear to be important for virulence and immunopathogenicity in mycobacteria, yet the functions of the PE/PPE domains remain an enigma. To decipher the role of these domains, we have characterized the triacylglycerol (TAG) hydrolase LipY from Mycobacterium tuberculosis, which is the only known PE protein expressing an enzymatic activity. The overproduction of LipY in mycobacteria resulted in a significant reduction in the pool of TAGs, consistent with the lipase activity of this enzyme. Unexpectedly, this reduction was more pronounced in mycobacteria overexpressing LipY lacking the PE domain [LipY(ΔPE)], suggesting that the PE domain participates in the modulation of LipY activity. Interestingly, Mycobacterium marinum contains a protein homologous to LipY, termed LipYmar, in which the PE domain is substituted by a PPE domain. As for LipY, overexpression of LipYmar in Mycobacterium smegmatis significantly reduced the TAG pool, and this was further pronounced when the PPE domain of LipYmar was removed. Fractionation studies and Western blot analysis demonstrated that both LipY and LipY(ΔPE) were mainly present in the cell wall, indicating that the PE domain was not required for translocation to this site. Furthermore, electron microscopy immunolabeling of LipY(ΔPE) clearly showed a cell surface localization, thereby suggesting that the lipase may interact with the host immune system. Accordingly, a strong humoral response against LipY and LipY(ΔPE) was observed in tuberculosis patients. Together, our results suggest for the first time that both PE and PPE domains can share similar functional roles and that LipY represents a novel immunodominant antigen.

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