Responses to Efferent Activation and Excitatory Response-Intensity Relations of Turtle Posterior-Crista Afferents

2000 ◽  
Vol 83 (3) ◽  
pp. 1224-1242 ◽  
Author(s):  
Alan M. Brichta ◽  
Jay M. Goldberg
Keyword(s):  
Head Movements ◽  
Maximal Response ◽  
Shock Train ◽  
Threshold Velocity ◽  
Nerve Branch ◽  
Excitatory Response ◽  
Response Intensity ◽  
Mixed Response ◽  
Excitatory Responses ◽  
Intensity Functions

Multivariate statistical formulas were used to infer the morphological type and longitudinal position of extracellularly recorded afferents. Efferent fibers were stimulated electrically in the nerve branch interconnecting the anterior and posterior VIIIth nerves. Responses of bouton (B) units depended on their inferred position: BP units (near the planum semilunatum) showed small excitatory responses; BT units (near the torus) were inhibited; BM units (in an intermediate position) had a mixed response, including an initial inhibition and a delayed excitation. Calyx-bearing (CD-high) units with an appreciable background discharge showed large per-train excitatory responses followed by smaller post-train responses that could outlast the shock train by 100 s. Excitatory responses were smaller in calyx-bearing (CD-low) units having little or no background activity than in CD-high units. Excitatory response-intensity functions, derived from the discharge during 2-s angular-velocity ramps varying in intensity, were fit by empirical functions that gave estimates of the maximal response ( r MAX), a threshold velocity ( v T), and the velocity producing a half-maximal response ( v 1/2). Linear gain is equal to r MAX/ v S, v S = v 1/2 − v T. v S provides a measure of the velocity range over which the response is nearly linear. For B units, r MAX declines by as much as twofold over the 2-s ramp, whereas for CD units, r MAXincreases by 15% during the same time period. At the end of the ramp, r MAX is on average twice as high in CD as in B units. Thresholds are negligible in most spontaneously active units, including almost all B and CD-high units. Silent CD-low units typically have thresholds of 10–100 deg/s. BT units have very high linear gains and v S < 10 deg/s. Linear gains are considerably lower in BP units and v S> 150 deg/s. CD-high units have intermediate gains and near 100 deg/s v S values. CD-low units have low gains and v S values ranging from 150 to more than 300 deg/s. The results suggest that BT units are designed to measure the small head movements involved in postural control, whereas BP and CD units are more appropriate for monitoring large volitional head movements. The former units are silenced by efferent activation, whereas the latter units are excited. This suggests that the efferent system switches the turtle posterior crista from a “postural” to a “volitional” mode.

Response properties of units in the dorsal cochlear nucleus of unanesthetized decerebrate gerbil

1996 ◽  
Vol 75 (4) ◽  
pp. 1411-1431 ◽  
Author(s):  
K. A. Davis ◽  
J. Ding ◽  
T. E. Benson ◽  
H. F. Voigt
Keyword(s):  
Dorsal Cochlear Nucleus ◽  
Type I ◽  
Type Ii ◽  
Decerebrate Cat ◽  
Excitatory Response ◽  
Type Iii ◽  
Type Iv ◽  
Noise Type ◽  
Rate Versus ◽  
Excitatory Responses

1. The electrophysiological responses of single units in the dorsal cochlear nucleus of unanesthetized decerebrate Mongolian gerbil (Meriones unguiculatus) were recorded. Units were classified according to the response map scheme of Evans and Nelson as modified by Young and Brownell, Young and Voigt, and Shofner and Young. Type II units have a V-shaped excitatory response map similar to typical auditory nerve tuning curves but little or no spontaneous activity (SpAc < 2.5 spikes/s) and little or no response to noise. Type I/III units also have a V-shaped excitatory map and SpAc < 2.5 spikes/s, but have an excitatory response to noise. Type III units have a V-shaped excitatory map with inhibitory sidebands, SpAc > 2.5 spikes/s, and an excitatory response to noise. Type IV-T units typically also have a V-shaped excitatory map with inhibitory sidebands, but have a highly nonmonotonic rate versus level response to best frequency (BF) tones like type IV units, SpAc > 2.5 spikes/s, and an excitatory response to noise. Type IV units have a predominantly inhibitory response map above an island of excitation of BF, SpAc > 2.5 spikes/s, and an excitatory response to noise. We present results for 133 units recorded with glass micropipette electrodes. The purpose of this study was to establish a normative response map data base in this species for ongoing structure/function and correlation studies. 2. The major types of units (type II, type I/III, type III, type IV-T, and type IV) found in decerebrate cat are found in decerebrate gerbil. However, the percentage of type II (7.5%) and type IV (11.3%) units encountered are smaller and the percentage of type III (62.4%) units is larger in decerebrate gerbil than in decerebrate cat. In comparison, Shofner and Young found 18.5% type II units, 30.6% type IV units, and 23.1% type III units using metal electrodes. 3. Two new unit subtypes are described in gerbil: type III-i and type IV-i units. Type III-i units are similar to type III units except that type III-i units are inhibited by low levels of noise and excited by high levels of noise whereas type III units have strictly excitatory responses to noise. Type IV-i units are similar to type IV units except that type IV-i units are excited by low levels of noise and become inhibited by high levels of noise whereas type IV units have strictly excitatory responses to noise. Type III-i units are approximately 30% of the type III population and type IV-i units are approximately 50% of the type IV population. 4. On the basis of the paucity of classic type II units and the reciprocal responses to broadband noise of type III-i and type IV-i units, we postulate that some gerbil type III-i units are the same cell type and have similar synaptic connections as cat type II units. 5. Type II and type I/III units are distinguished from one another on the basis of both their relative noise response, rho, and the normalized slope of the BF tone rate versus level functions beyond the first maximum. Previously, type II units were defined to be those nonspontaneously active units with rho values < 0.3 where rho is defined as the ratio of the maximum noise response minus spontaneous rate to the maximum BF tone response minus spontaneous rate. In the gerbil, the average rho value for type II units is 0.25, although a few values are > 0.3, and the rate-level curves are consistently nonmonotonic with normalized slopes steeper than than -0.007/dB. The average rho value for type I/III units is 0.54, although a few values are < 0.3, and the rate-level curves tend to saturate with slopes shallower than -0.006/dB. In general, the response properties of type II units recorded in gerbil are similar to those recorded in decerebrate cat. 6. In comparison to decerebrate cat, the lower percentage of type IV units recorded in decerebrate gerbil may be due to a species difference (a reduced number of type II units in gerbil) or an electrode bias.

Projections from the Ventral Tegmental Area to the Olfactory Tubercle in the Rat

1987 ◽  
Vol 96 (2) ◽  
pp. 151-157 ◽  
Author(s):  
Kenneth E. Mooney ◽  
Akira Inokuchi ◽  
James B. Snow ◽  
Charles P. Kimmelman
Keyword(s):  
Ventral Tegmental Area ◽  
Inhibitory Response ◽  
Inhibitory Influence ◽  
Olfactory Tubercle ◽  
Mixed Response ◽  
Neural Connection ◽  
Ventral Tegmental ◽  
Excitatory Responses ◽  
Stimulation Of

The projection between the ventral tegmental area (VTA) and the olfactory tubercle (OT) was examined electrophysiologically in the rat. Stimulation of the olfactory bulb (OB) determined if the OT neurons were olfactory-related. Ipsilateral VTA stimulation produced a change in neuronal activity in 77% of the neurons tested, with 41% being inhibited, 24% excited, and 12% had mixed response. Contralateral VTA stimulation produced changes in only 38%. Intravenous administration of haloperidol was used in examination of the role of dopamine in this neural connection. The results suggest that the VTA-induced inhibitory response on OT neurons is mediated by dopamine, whereas excitatory responses are not. The VTA inhibitory influence projects primarily to olfactory-related neurons, since 60% of olfactory-related OT neurons were inhibited—as compared to 34% of non-olfactory-related neurons. This study documents electrophysiologically the VTA-OT connection and suggests that the dopaminergic input may modulate olfactory information projected to the OT from the OB. It also supports the concept that the OT acts as an integration center in central olfactory processing.

Abnormal Stimulus-Response Intensity Functions in Posttraumatic Stress Disorder: An Electrophysiological Investigation

2002 ◽  
Vol 159 (10) ◽  
pp. 1689-1695 ◽  
Author(s):  
Jeffrey David Lewine ◽  
Robert J. Thoma ◽  
Sherri L. Provencal ◽  
Chris Edgar ◽  
Gregory A. Miller ◽  
...  
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Posttraumatic Stress ◽  
Stress Disorder ◽  
Electrophysiological Investigation ◽  
Response Intensity ◽  
Stimulus Response ◽  
Intensity Functions

Contribution of GABAergic inhibition to the response characteristics of auditory units in the avian forebrain

1988 ◽  
Vol 59 (6) ◽  
pp. 1673-1689 ◽  
Author(s):  
C. M. Muller ◽  
H. Scheich
Keyword(s):  
Free Field ◽  
Poor Response ◽  
Wide Band ◽  
Inhibitory Response ◽  
Gabaergic Inhibition ◽  
Response Component ◽  
Excitatory Response ◽  
Response Characteristics ◽  
Iontophoretic Application ◽  
Excitatory Responses

1. We tested the contribution of GABAergic inhibition to the response characteristics of 213 neurons in the auditory telencephalon of chronically prepared nonanesthetized chickens. Extracellular recordings were obtained with multibarrel glass electrodes containing a tungsten wire. Auditory stimuli consisted of tones, two-tone combinations, and noise bursts presented either free field or via earphones. 2. Response properties of the neurons were studied both before and during iontophoretic application of GABA, glutamate, bicuculline methiodide (BIC), and acetylcholine. 3. During BIC application excitatory responses were facilitated. With the exception of transient off-responses, which occasionally appeared only in the BIC condition, the temporal response patterns to tone stimuli at the units' best frequency usually were unaltered. In no case was an inhibitory response component to binaurally presented pure tones antagonized by BIC. 4. BIC iontophoresis enlarged the isointensity-response areas of the vast majority of neurons in the structures of the auditory forebrain lying postsynaptic to the thalamorecipient layer L2. This effect was not obtained when neurons were depolarized to perithreshold levels with glutamate. 5. Two-tone stimulation resulted in a suppression of the excitatory response to a neuron's best frequency when the second frequency lay outside the excitatory response area. In lamina L2, the frequency range inducing two-tone suppression was narrow, and the suppressive effect was not antagonized by BIC. In the postsynaptic layers, frequencies up to three octaves from the neurons' best frequency induced two-tone suppression that was sensitive to BIC. In addition, these neurons also displayed a BIC-insensitive suppression similar to the one seen in layer L2. 6. Neurons displaying no or only a poor response to white-noise stimulation strongly responded to this wide-band stimulus during BIC iontophoresis. 7. Neurons without tone responses usually displayed clear response areas to tones during BIC application. Iontophoretic application of acetylcholine, but not glutamate, also induced such tone responses. Two-tone combinations with frequencies lying within the response areas observed in the BIC condition elicited excitatory responses after full recovery from the BIC application. 8. During BIC iontophoresis nonmonotonic intensity-response functions were converted to monotonic functions in most of the neurons studied. 9. A model of GABAergic inhibitory interactions is proposed that is based on two independent GABAergic systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Muscarinic inhibition of canine small intestinal motility in vivo

1985 ◽  
Vol 248 (5) ◽  
pp. G526-G531 ◽  
Author(s):  
J. E. Fox ◽  
E. E. Daniel ◽  
J. Jury ◽  
H. Robotham
Keyword(s):  
Muscarinic Receptor ◽  
Feedback Loop ◽  
Inhibitory Effects ◽  
Excitatory Response ◽  
Small Intestinal Motility ◽  
Reserpine Treatment ◽  
Small Intestinal ◽  
Excitatory Responses

The quiescent canine gastrointestinal tract responsed to close intraarterial acetylcholine with an atropine-sensitive, hexamethonium, and tetrodotoxin-insensitive contraction, thus suggesting acetylcholine interacts with a muscarinic receptor located on the muscle. When the gut is actively contracting (spontaneously, in response to field stimulation or to motilin), acetylcholine caused a contraction followed by prolonged inhibition of contractions. No such inhibition was apparent after tetrodotoxin; therefore, the receptor for acetylcholine-induced inhibition was apparently on nerves. Neither the acetylcholine-induced excitation nor the inhibition was altered by hexamethonium or reserpine treatment. Both inhibitory and excitatory responses were greatly reduced by atropine, suggesting that both receptors were muscarinic in nature. McNeil A343 produced inhibition but no excitation. Tetrodotoxin, hexamethonium, reserpine, and pirenzepine all increased the concentration of McNeil A343 required for production of 50% inhibition, suggesting it acts via multiple mechanisms. Furthermore, pirenzepine reduced both the inhibitory and excitatory response to acetylcholine, suggesting that it is nonselective in its action on the neural inhibitory or muscular excitatory receptors. We suggest that the presynaptic muscarinic receptor responsible for inhibitory effects of acetylcholine is on the postganglionic cholinergic neuron itself and constitutes an important negative-feedback loop to reduce excessive cholinergic output. Although such a mechanism has been found in vitro previously, this is the first report in vivo in canine small intestine.

scholarly journals Static and dynamic properties of synaptic transmission at the cyto-neural junction of frog labyrinth posterior canal.

1989 ◽  
Vol 94 (2) ◽  
pp. 303-327 ◽  
Author(s):  
M L Rossi ◽  
C Bonifazzi ◽  
M Martini ◽  
R Fesce
Keyword(s):  
Angular Velocity ◽  
Synaptic Transmission ◽  
Afferent Nerve ◽  
Fluctuation Analysis ◽  
Excitatory Postsynaptic Potential ◽  
Posterior Canal ◽  
Phase Lead ◽  
Excitatory Responses ◽  
Intensity Functions ◽  
Spike Firing

The properties of synaptic transmission have been studied at the cyto-neural junction of the frog labyrinth posterior canal by examining excitatory postsynaptic potential (EPSP) activity recorded intraaxonally from the afferent nerve after abolishing spike firing by tetrodotoxin. The waveform, amplitude, and rate of occurrence of the EPSPs have been evaluated by means of a procedure of fluctuation analysis devised to continuously monitor these parameters, at rest as well as during stimulation of the semicircular canal by sinusoidal rotation at 0.1 Hz, with peak accelerations ranging from 8 to 87 deg.s-2. Responses to excitatory and inhibitory accelerations were quantified in terms of maximum and minimum EPSP rates, respectively, as well as total numbers of EPSPs occurring during the excitatory and inhibitory half cycles. Excitatory responses were systematically larger than inhibitory ones (asymmetry). Excitatory responses were linearly related either to peak acceleration or to its logarithm, and the same occurred for inhibitory responses. In all units examined, the asymmetry of the response yielded nonlinear two-sided input-output intensity functions. Silencing of EPSPs during inhibition (rectification) was never observed. Comparison of activity during the first cycle of rotation with the average response over several cycles indicated that variable degrees of adaptation (up to 48%) characterize the excitatory response, whereas no consistent adaptation was observed in the inhibitory response. All fibers appeared to give responses nearly in phase with angular velocity, at 0.1 Hz, although the peak rates generally anticipated by a few degrees the peak angular velocity. From the data presented it appears that asymmetry, adaptation, and at least part of the phase lead in afferent nerve response are of presynaptic origin, whereas rectification and possible further phase lead arise at the encoder. To confirm these conclusions a simultaneous though limited study of spike firing and EPSP activity has been attempted in a few fibers.

Activity Profiles of Single Neurons in Caudal Anterior Cingulate Cortex During Trace Eyeblink Conditioning in the Rabbit

2003 ◽  
Vol 90 (2) ◽  
pp. 599-612 ◽  
Author(s):  
Aldis P. Weible ◽  
Craig Weiss ◽  
John F. Disterhoft
Keyword(s):  
Anterior Cingulate Cortex ◽  
Neuronal Activity ◽  
Eyeblink Conditioning ◽  
Neuronal Response ◽  
Trace Conditioning ◽  
Cingulate Cortex ◽  
Anterior Cingulate ◽  
Excitatory Response ◽  
Excitatory Responses ◽  
Trace Eyeblink Conditioning

Acquisition of trace eyeblink conditioning involves the association of a conditioned stimulus (CS) with an unconditioned stimulus (US) separated by a stimulus-free trace interval. This form of conditioning is dependent upon the hippocampus and the caudal anterior cingulate cortex (AC), in addition to brain stem and cerebellar circuitry. Hippocampal involvement in trace eyeblink conditioning has been studied extensively, but the involvement of caudal AC is less well understood. In the present study, we compared neuronal responses from rabbits given either paired (trace conditioning) or unpaired (pseudoconditioning) presentations of the CS and US. Presentation of the CS elicited significant increases in neuronal activity at the onset of both trace conditioning and pseudoconditioning. A robust CS-elicited neuronal response persisted throughout the first 2 days of trace conditioning, declining gradually across subsequent training sessions. In contrast, the magnitude of the CS-elicited excitatory response during pseudoconditioning began to decline within the first 10 trials. Neurons exhibiting excitatory responses to the CS during trace conditioning also exhibited excitatory responses to the US that were significantly greater in magnitude than US-elicited responses during pseudoconditioning. CS-elicited decreases in neuronal activity became more robust over the course of trace conditioning compared to pseudoconditioning. Reductions in activity during the CS interval consistently preceded excitation in both training groups, suggesting that the CS-elicited decreases in neuronal activity may serve to increase the signal-to-noise ratio of the excitatory response to the tone. Taken together, these data suggest that the caudal AC is involved early in trace eyeblink conditioning and that maintenance of the CS-elicited excitatory response may serve to signal the salience of the tone.

GABAA receptor antagonist bicuculline alters response properties of posteroventral cochlear nucleus neurons

1992 ◽  
Vol 67 (3) ◽  
pp. 738-746 ◽  
Author(s):  
P. S. Palombi ◽  
D. M. Caspary
Keyword(s):  
Receptor Antagonist ◽  
Gabaa Receptor ◽  
Cochlear Nucleus ◽  
Discharge Rate ◽  
Response Patterns ◽  
Excitatory Response ◽  
Gabaa Receptor Antagonist ◽  
Intensity Functions ◽  
Spike Latency ◽  
Post Onset

1. The role of GABAergic inhibitory inputs onto posteroventral cochlear nucleus (PVCN) neurons in the anesthetized chinchilla was investigated through iontophoretic application of the GABAA receptor agonist muscimol and the GABAA receptor antagonist bicuculline. The majority of the neurons studied displayed phasic temporal response patterns. 2. All the neurons were sensitive to bicuculline and displayed an increase in discharge rate, which was greatest during the post-onset portion of the response. Most of the tested neurons were also sensitive to muscimol, which appeared to mimic the putative effect of endogenous GABA. 3. Bicuculline reduced the average first-spike latency and the average variability of the first-spike latency. Muscimol had the opposite effect. 4. Bicuculline did not significantly alter the threshold but rather increased discharge rate at suprathreshold intensities. 5. The width of the excitatory response area was not significantly increased by application of bicuculline. The increase in discharge rate occurred within the units' excitatory response areas. 6. The shape of the rate-intensity functions was not altered by bicuculline application. 7. We conclude that GABAergic inhibitory inputs control the post-onset discharge rate of some PVCN neurons. They may suppress tonic activity, resulting in more phasic discharge patterns.

GABA inputs control discharge rate primarily within frequency receptive fields of inferior colliculus neurons

1996 ◽  
Vol 75 (6) ◽  
pp. 2211-2219 ◽  
Author(s):  
P. S. Palombi ◽  
D. M. Caspary
Keyword(s):  
Inferior Colliculus ◽  
Discharge Rate ◽  
Neuronal Response ◽  
Frequency Bandwidth ◽  
Complex Signals ◽  
Excitatory Response ◽  
Response Properties ◽  
Gaba Inhibition ◽  
Intensity Functions ◽  
Response Area

1. Recent studies have suggested that gamma-aminobutyric acid (GABA) inputs shape monaural and binaural neuronal response properties in the central nucleus of the inferior colliculus (CIC). CIC neurons receive major inhibitory GABAergic projections from intrinsic, commissural, and extrinsic sources. Many GABAergic projections now are thought to arise from cells that are tonotopically matched to their CIC targets. 2. We tested the hypothesis that GABA circuits are aligned primarily within the CIC target neuron's excitatory response area and therefore have their greatest effects on discharge rate mainly within that frequency domain. GABA inhibition was examined by recording families of isointensity contours before, during, and after GABAA receptor blockade. Iontophoretic application of bicuculline-methiodide (BMI) was used to block GABAA receptors. Quantitative measures of frequency bandwidth and z-score analysis of discharge rate within the excitatory receptive field were used to compare pre- and postdrug conditions. 3. Chinchilla CIC unit response properties were similar to those described for other species, with a high percentage of phasic temporal response patterns and nonmonotonic rate-intensity functions in response to monaural contralateral characteristic frequency (CF) tones. Binaural responses of most CIC neurons showed suppression of contralaterally evoked responses by ipsilateral stimulation. 4. For 85% of CIC neurons, blockade of GABAA inputs was found to increase discharge rate within the excitatory response area. Forty-five percent were classified as near-CF changes and 32% as near-CF and low side. Changes in lateral/flanking inhibition in the absence of near-CF changes were never observed. Forty-one percent of CIC neurons displayed less than a 10% increase in frequency bandwidth at 25-35 dB above threshold with BMI application. 5. These data suggest that GABA inhibition arises primarily from neurons with inhibitory fields aligned with their CIC targets. Thus the effect of the inhibition is primarily contained within or overlapping each target neuron's excitatory response area. CIC GABAergic circuits may function to adjust the gain needed for coding complex signals over a wide dynamic range.

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