Dorsal Nucleus Raphé

The dorsal granular ridge (DGR) of the elasmobranch vestibulolateral cerebellum is the source of a parallel fiber projection to the electrosensory dorsal nucleus. We report that the DGR in Raja erinacea contains a large percentage of units with activity modulated by the animal's own ventilation. These include propriosensory and electrosensory units, responding to either ventilatory movements or the resulting electroreceptive reafference, and an additional population of units in which activity is phase-locked to the ventilatory motor commands even in animals paralyzed to block all ventilatory movements. A principal function of processing in the dorsal nucleus is the elimination of ventilatory noise in second-order electrosensory neurons. The existence of these ventilatory motor corollary discharge units, along with other DGR units responsive to ventilatory movements, suggests that the parallel fiber projection is involved in the noise cancellation mechanisms.

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T2-T5 spinothalamic neurons projecting to medial thalamus with viscerosomatic input

Journal of Neurophysiology ◽

10.1152/jn.1985.54.1.73 ◽

1985 ◽

Vol 54 (1) ◽

pp. 73-89 ◽

Cited By ~ 61

Author(s):

W. S. Ammons ◽

M. N. Girardot ◽

R. D. Foreman

Keyword(s):

Receptive Fields ◽

Cell Group ◽

Spinothalamic Tract ◽

Medial Thalamus ◽

Dorsal Nucleus ◽

Afferent Fibers ◽

C Fiber ◽

Antidromic Responses ◽

Alpha Chloralose ◽

Stimulation Of

Spinothalamic tract neurons projecting to medial thalamus (M-STT cells), ventral posterior lateral nucleus (VPL) of the thalamus (L-STT cells), or both thalamic regions (LM-STT cells) were studied in 19 monkeys anesthetized with alpha-chloralose. Twenty-seven M-STT cells were antidromically activated from nucleus centralis lateralis, nucleus centrum medianum, or the medial dorsal nucleus. Stimulation of VPL elicited antidromic responses from 22 cells and 13 cells were activated from both VPL and medial thalamus. Antidromic conduction velocities of M-STT cells were significantly slower than those of L-STT or LM-STT cells. M-STT cells were located in laminae I, IV, V, and VII with greater numbers found in the deepest laminae. L-STT cells were located mostly in lamina IV, whereas most LM-STT cells were found in lamina V. Twenty-four of 27 M-STT cells, all L-STT cells, and all LM-STT cells received input from both cardiopulmonary sympathetic and somatic afferent fibers. WDR cells were most common among the L-STT and LM-STT groups, whereas HT cells were the most common class in the M-STT cell group. Excitatory receptive fields of M-STT cells were large, and often bilateral. Receptive fields of L-STT cells were simple and never bilateral. Receptive fields of LM-STT cells could be similar to M-STT or L-STT cells. Thirty-three percent of the M-STT cells, 37% of the L-STT cells, and 62% of the LM-STT cells had inhibitory receptive fields. Inhibition was elicited most often by a noxious pinch of the hindlimbs. Sixteen of 23 (70%) M-STT cells received C-fiber cardiopulmonary sympathetic input in addition to A-delta-fiber input. The other 7 cells received only A-delta-fiber input. Only 45% of the L-STT cells and 38% of the LM-STT cells received both A-delta- and C-fiber inputs. The maximum number of spikes elicited by A-delta-input was related to segmental locations for L-STT cells with greatest responses in T2 and lesser responses in more caudal segments; however, no such trend was apparent for M-STT cells or for responses to C-fiber input for either group. Electrical stimulation of the left thoracic vagus nerve inhibited 7 of 18 M-STT cells, 10 of 16 L-STT cells, and 6 of 12 LM-STT cells. These results are the first description of visceral input to cells projecting to medial thalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

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Hyperpolarization-Activated Inward Current in Neurons of the Rat's Dorsal Nucleus of the Lateral Lemniscus In Vitro

Journal of Neurophysiology ◽

10.1152/jn.1997.78.5.2235 ◽

1997 ◽

Vol 78 (5) ◽

pp. 2235-2245 ◽

Cited By ~ 27

Author(s):

Xiao Wen Fu ◽

Borys L. Brezden ◽

Shu Hui Wu

Keyword(s):

Membrane Potential ◽

Input Resistance ◽

Resting Potential ◽

Extracellular Potassium ◽

Current Clamp ◽

Lateral Lemniscus ◽

Inward Current ◽

Dorsal Nucleus ◽

Maximal Activation

Fu, Xiao Wen, Borys L. Brezden, and Shu Hui Wu. Hyperpolarization-activated inward current in neurons of the rat's dorsal nucleus of the lateral lemniscus in vitro. J. Neurophysiol. 78: 2235–2245, 1997. The hyperpolarization-activated current ( I h) underlying inward rectification in neurons of the rat's dorsal nucleus of the lateral lemniscus (DNLL) was investigated using whole cell patch-clamp techniques. Patch recordings were made from DNLL neurons of young rats (21–30 days old) in 400 μm tissue slices. Under current clamp, injection of negative current produced a graded hyperpolarization of the cell membrane, often with a gradual sag in the membrane potential toward the resting value. The rate and magnitude of the sag depended on the amount of hyperpolarizing current. Larger current resulted in a larger and faster decay of the voltage. Under voltage clamp, hyperpolarizing voltage steps elicited a slowly activating inward current that was presumably responsible for the sag observed in the voltage response to a steady hyperpolarizing current recorded under current clamp. Activation of the inward current ( I h) was voltage and time dependent. The current just was seen at a membrane potential of −70 mV and was activated fully at −140 mV. The voltage value of half-maximal activation of I h was −78.0 ± 6.0 (SE) mV. The rate of I h activation was best approximated by a single exponential function with a time constant that was voltage dependent, ranging from 276 ± 27 ms at −100 mV to 186 ± 11 ms at −140 mV. Reversal potential ( E h) of I h current was more positive than the resting potential. Raising the extracellular potassium concentration shifted E h to a more depolarized value, whereas lowering the extracellular sodium concentration shifted E h in a more negative direction. I h was sensitive to extracellular cesium but relatively insensitive to extracellular barium. The current amplitude near maximal-activation (about −140 mV) was reduced to 40% of control by 1 mM cesium but was reduced to only 71% of control by 2 mM barium. When the membrane potential was near the resting potential (about −60 mV), cesium had no effect on the membrane potential, current-evoked firing rate and input resistance but reduced the spontaneous firing. When the membrane potential was more negative than −70 mV, cesium hyperpolarized the cell, decreased current-evoked firing and increased the input resistance. I h in DNLL neurons does not contribute to the normal resting potential but may enhance the extent of excitation, thereby making the DNLL a consistently powerful inhibitory source to upper levels of the auditory system.

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The Anterior Nuclei and Lateral Dorsal Nucleus

The Thalamus ◽

10.1007/978-1-4615-1749-8_14 ◽

1985 ◽

pp. 673-697 ◽

Cited By ~ 1

Author(s):

Edward G. Jones

Keyword(s):

Dorsal Nucleus

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The roles of GABAergic and glycinergic inhibition on binaural processing in the dorsal nucleus of the lateral lemniscus of the mustache bat

Journal of Neurophysiology ◽

10.1152/jn.1994.71.6.1999 ◽

1994 ◽

Vol 71 (6) ◽

pp. 1999-2013 ◽

Cited By ~ 55

Author(s):

L. Yang ◽

G. D. Pollak

Keyword(s):

Tone Burst ◽

Gabaergic Inhibition ◽

Gamma Aminobutyric Acid ◽

Lateral Lemniscus ◽

Dorsal Nucleus ◽

Iontophoretic Application ◽

Monaural Stimulation ◽

Contralateral Ear ◽

Glycinergic Inhibition ◽

Stimulation Of

1. We studied the monaural and binaural response properties of 99 neurons in the dorsal nucleus of the lateral lemniscus (DNLL) of the mustache bat before and during the iontophoretic application of antagonists that blocked gamma-aminobutyric acid-A (GABAA) receptors (bicuculline) or glycine receptors (strychnine). All cells were driven by monaural stimulation of the contralateral ear, whereas monaural stimulation of the ipsilateral ear never evoked discharges. The binaural properties of 81 neurons were determined by holding the intensity constant at the contralateral ear and presenting a variety of intensities to the ipsilateral ear. This procedure generated interaural intensity disparity (IID) functions and allowed us to determine the effect of ipsilaterally evoked inhibition on a constant excitatory drive evoked by the contralateral ear. 2. One of the main findings is that the IID functions in the majority of DNLL neurons were not affected by application of either strychnine or bicuculline. Blocking glycinergic inhibition with strychnine had no effect on the IID functions in 75% of the cells studied. However, strychnine did change the IID functions in approximately 25% of the DNLL population. In those cells glycinergic inhibition appeared to be partially, or, in a few cases, entirely responsible for the ipsilaterally evoked spike suppression. In contrast, blocking GABAergic inhibition with bicuculline had no discernible effect on the ipsilaterally evoked spike suppression in any of the excitatory/inhibitory cells that we recorded. GABAergic inhibition, therefore, plays no role in the formation of IID functions of neurons in the DNLL. Furthermore, the results suggest that glycinergic inhibition also does not contribute to the suppression of spikes evoked by stimulation of the contralateral ear in the vast majority of DNLL neurons. 3. Although the majority of IID functions were not influenced when either GABAergic or glycinergic innervation was blocked, ipsilateral stimulation alone evoked both a glycinergic and GABAergic inhibition in most DNLL cells. These inhibitory events were demonstrated in 18 other cells by evoking discharges with the iontophoretic application of glutamate. Stimulating the ipsilateral ear alone under these conditions caused a suppression of the glutamate-evoked discharges. Furthermore, the spike suppression persisted for a period of time that was longer than the duration of the tone burst at the ipsilateral ear. 4. The application of bicuculline or strychnine had different effects on the glutamate-elicited spikes. Bicuculline reduced the duration of the inhibition, and it was always the latter portion of the inhibition that was abolished by bicuculline. In more than half of the cells studied strychnine also reduced the duration of the inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

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Spectral Composition of Concurrent Noise Affects Neuronal Sensitivity to Interaural Time Differences of Tones in the Dorsal Nucleus of the Lateral Lemniscus

Journal of Neurophysiology ◽

10.1152/jn.00275.2007 ◽

2007 ◽

Vol 98 (5) ◽

pp. 2705-2715 ◽

Cited By ~ 5

Author(s):

Ida Siveke ◽

Christian Leibold ◽

Benedikt Grothe

Keyword(s):

White Noise ◽

Response Rate ◽

Spectral Composition ◽

Low Frequency ◽

Maximal Response ◽

Lateral Lemniscus ◽

Interaural Time Differences ◽

Binaural Cues ◽

Dorsal Nucleus ◽

Monaural Stimulation

We are regularly exposed to several concurrent sounds, producing a mixture of binaural cues. The neuronal mechanisms underlying the localization of concurrent sounds are not well understood. The major binaural cues for localizing low-frequency sounds in the horizontal plane are interaural time differences (ITDs). Auditory brain stem neurons encode ITDs by firing maximally in response to “favorable” ITDs and weakly or not at all in response to “unfavorable” ITDs. We recorded from ITD-sensitive neurons in the dorsal nucleus of the lateral lemniscus (DNLL) while presenting pure tones at different ITDs embedded in noise. We found that increasing levels of concurrent white noise suppressed the maximal response rate to tones with favorable ITDs and slightly enhanced the response rate to tones with unfavorable ITDs. Nevertheless, most of the neurons maintained ITD sensitivity to tones even for noise intensities equal to that of the tone. Using concurrent noise with a spectral composition in which the neuron's excitatory frequencies are omitted reduced the maximal response similar to that obtained with concurrent white noise. This finding indicates that the decrease of the maximal rate is mediated by suppressive cross-frequency interactions, which we also observed during monaural stimulation with additional white noise. In contrast, the enhancement of the firing rate to tones at unfavorable ITD might be due to early binaural interactions (e.g., at the level of the superior olive). A simple simulation corroborates this interpretation. Taken together, these findings suggest that the spectral composition of a concurrent sound strongly influences the spatial processing of ITD-sensitive DNLL neurons.

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