Nucleus Angularis

In birds, cochlear Nucleus angularis (NA) is an obligatory relay for intensity processing.  

We investigated the short-term synaptic plasticity of the inputs to the bird's cochlear Nucleus angularis (NA), which encodes intensity information, by using chick embryonic brain slices and trains of electrical stimulation.  

In the medulla of 7- and 8-day embryos, we identified four response areas, corresponding to ipsilateral Nucleus magnocellularis (NM) and Nucleus angularis (NA), which receive the auditory afferents, and ipsi- and contralateral Nucleus laminaris (NL), which receive projections from NM.  

Nucleus magnocellularis (NM), Nucleus angularis (NA), and nucleus laminaris (NL), second- and third-order auditory neurons in the avian brainstem, receive GABAergic input primarily from the superior olivary nucleus (SON).  

Nucleus angularis (NA), one of the two cochlear nuclei in birds, is important for processing sound intensity for localization and most likely has role in sound recognition and other auditory tasks.  

One possible exception to this parallel organization is the inhibitory input provided by the superior olivary nucleus (SON) to Nucleus angularis (NA), nucleus magnocellularis (NM), and nucleus laminaris (NL) and contralateral SON (SONc).  

The Nucleus angularis (NA) initiated NR1 expression before E12 that became more prominent after hatching.  

Evidence of a topographic map was also observed in the other primary auditory brainstem nucleus, Nucleus angularis.  

The cochlear Nucleus angularis (NA) is widely assumed to form the starting point of a brain stem pathway for processing sound intensity in birds.  

In order to understand how sound intensity information is extracted and processed in the auditory nuclei, we investigated the neuronal excitability in the Nucleus angularis (NA) of the chicken (P0-5) and the chicken embryo (E16-21).  

Both the avian cochlear Nucleus angularis and the mammalian cochlear nuclei have heterogeneous cell populations, and similar responses to sound.  

In vitro whole cell recording revealed intrinsic firing properties and single-cell morphology in the cochlear Nucleus angularis (NA) of the chick.  

The Nucleus angularis (NA), one of the two cochlear nuclei of birds, plays an important role in the processing of sound intensity. The courses of their axonal branches were used to construct a composite average map of the tonotopic frequency representation in the Nucleus angularis. Nucleus angularis in the barn owl, as seen in frontal sections, resembles a sheet of cells bent approximately into an S shape. Auditory nerve fibers of a given CF always entered the Nucleus angularis within a well-restricted area and then traveled along their isofrequency band within the NA while branching off terminals. The basic tonotopic organization is comparable to that found in other birds, the major differences being the large size and unusual shape of the barn owl's Nucleus angularis..  

Some penetrations yielded predominantly monaural responses with a fairly broad dynamic range, similar to those recorded from the ventral nucleus of the lateral lemniscus (LLV) and the cochlear Nucleus angularis, whereas other penetrations contained predominantly binaural responses sensitive to interaural time differences (ITD).  

The cochlear Nucleus angularis (NA) of the barn owl (Tyto alba) was analyzed using Golgi, Nissl, and tract tracing techniques.  

Nucleus magnocellularis (NM) and Nucleus angularis receive tonotopically ordered cochlear input.  

The pigeon cochlear Nucleus angularis (NA) and nucleus magnocellularis (NM) were analyzed with Golgi and Nissl techniques.  

In the hindbrain, CR-IR was first observed in the rostromedial regions of the cochlear nucleus magnocellularis and the nucleus laminaris, and in the dorsal regions of the Nucleus angularis and in the nucleus of the lateral lemniscus.  

Located in the ventrolateral region of the avian brainstem, the superior olivary nucleus (SON) receives inputs from Nucleus angularis (NA) and nucleus laminaris (NL) and projects back to NA, NL, and nucleus magnocellularis (NM).  

Neurons in VLVp receive excitatory input from the contralateral Nucleus angularis, and inhibitory input from the contralateral VLVp.  

In search for an alternative for CAP recordings, intracranial recordings of acoustically evoked field potentials from the Nucleus angularis/magnocellularis were made in pigeons using stereotactically placed electrodes. The field potentials recorded from the Nucleus angularis/magnocellularis contain a significant contribution from the auditory nerve, as large in amplitude as the CAP recorded at the round window. Threshold curves as a function of frequency could be determined with an automated method from the Nucleus angularis/magnocellularis with the same sensitivity and accuracy as from the round window CAP within a few minutes.  

In the cochlear Nucleus angularis (NA) and nucleus magnocellularis (NM), 30% to 40% of the neurons die after otocyst removal, the survivors are shrunken, and some neurons in the NA migrate to an abnormal position in the brain stem.  

The different cell types of the cochlear Nucleus angularis and the superior olive were characterized by heterogeneous GluR2/3 and 4 immunostaining.  

120:463-473) reported finding a projection of lagenar fibers to parts of the cochlear nuclei (nucleus magnocellularis and Nucleus angularis).  

The projections of Nucleus angularis were found to terminate throughout most of the contralateral central nucleus except the dorsomedial portion at rostral levels, where the majority of the projections of nucleus laminaris were concentrated. Nucleus angularis (and to a lesser extent nucleus laminaris) was also found to have substantial projections to certain noncentral toral nuclei, in particular to the caudomedial shell nucleus of Puelles et al.  

As regards the cochlear nuclei, we found that Nucleus angularis derives from r3 to r6, nucleus laminaris from r5 to r6, nucleus magnocellularis from r6 to r7 and nucleus olivaris superior from r5.  

The excitation arrives by a direct input from the contralateral Nucleus angularis, a cochlear nucleus, and the inhibition is mediated by a commissural projection that interconnects the VLVps of the two sides.  

Nucleus angularis lateralis consists of "spindle" cells. Lastly, Nucleus angularis medialis contains a population of large neurons called "duckhead" and "multipolar" cells, and a population of smaller neurons called "bulb" and "agranular" cells. In nucleus magnocellularis medialis and Nucleus angularis medialis, primary afferents form both chemical and electrical synapses with resident neurons.  

Projections to the OS originate bilaterally in the cochlear nuclei (Nucleus angularis) and the nucleus laminaris. Glycine-transporting cells were found ipsilaterally in the Nucleus angularis and the nucleus laminaris.  

In addition, the penetration angle permitted recordings from units in both cochlear nuclei, nucleus magnocellularis and Nucleus angularis (probably mostly cochlear afferents), in the same animal.  

This group of fusiform neurons has been named the Nucleus angularis grisea periventricularis (NAGP).  

These included neurons of nMAG, the Nucleus angularis, the nucleus laminaris, the cochlear ganglion, the Purkinje cell layer of the cerebellum, the ventral horn of the spinal cord, and the brainstem nucleus of the glossopharyngeal nerve (ncIX).  

No ChAT-I neurons or fibers were observed in NM, Nucleus angularis, nucleus laminaris, in the nuclei of the lateral lemniscus, or in the nucleus mesencephalicus lateralis pars dorsalis.  

Primary auditory nerve fibers were labelled in the barn owl by localized horseradish peroxidase (HRP) injections into the cochlear Nucleus angularis.  

Nucleus angularis projects to all of the nuclei and subdivisions of nuclei that belong to the intensity processing pathway. Acetylcholinesterase stained all regions that contain terminal fields of Nucleus angularis and thus provided discrimination between the time and intensity pathways.  

The nature of the enhancement and suppression of the click evoked AEPs during continuous pure tones was clearly different from those in recordings from the nucleus magnocellularis, Nucleus angularis and Field L in respect to the probability of occurrence of enhancement and suppression..  

Each auditory nerve fiber enters the brain and divides to terminate in both the cochlear Nucleus angularis and the cochlear nucleus magnocellularis. The lateral branch of the auditory nerve innervates the Nucleus angularis and gives rise to a major and a minor terminal field.  

A monoclonal antibody to the GABAR/benzodiazepine/chloride channel complex and radiolabeled ligand binding using [ 3H]-muscimol, a GABA agonist, revealed labeling in nucleus magnocellularis (NM), nucleus laminaris (NL), Nucleus angularis (NA), and the superior olive (SO) in both posthatch and embryonic chicks.  

In contrast, the nuclei with essentially or exclusively sensory components (i.e., Nucleus angularis, nucleus laminaris, nucleus magnocellularis) arise from the alar plate.  

Nucleus angularis neuroblasts migrate later in development, after E6.5.  

Neurons whose peripheral processes contacted tectorial hair cells in the cochlea projected to three divisions of the cochlear nucleus: nucleus magnocellularis lateralis (NML), nucleus magnocellularis medialis (NMM), and Nucleus angularis lateralis (NAL). Neurons whose peripheral processes contacted free-standing hair cells projected primarily to the Nucleus angularis medialis (NAM), although some also sent a single, thin branch to the NML; these neurons never projected to NAL or NMM.  

Physiological recordings were made from single units in the two divisions of the chick cochlear nucleus-Nucleus angularis (NA) and nucleus magnocellularis (NM). In particular, it was of interest to determine if Nucleus angularis and magnocellularis code for separate features of sound stimuli, such as temporal and intensity information. Neurons in Nucleus angularis tend to have low spontaneous discharge rates while magnocellular units have high levels of spontaneous firing.  

Spontaneous discharge rate was analyzed quantitatively for LF units recorded from Nucleus angularis.  

In the intensity pathway, dense immunoreactive terminals are distributed throughout the cochlear Nucleus angularis, which also contains a small number of GABAergic neurons.  

Nucleus angularis (NA) contains some GABAergic cells.  

During embryonic development, little Gly-I is present in nucleus magnocellularis (NM), nucleus laminaris (NL), or Nucleus angularis (NA).  

The shell surrounds the core and is defined by the terminal field of the Nucleus angularis, one of the cochlear nuclei.  

The well-developed cochlear nuclear complex includes the Nucleus angularis, nuclei magnocellulares medialis and lateralis, and nucleus laminaris. The primary cochlear fibers coursing in the posterior root terminate in Nucleus angularis, nuclei magnocellulares medialis and lateralis, and the inner cell strand of nucleus laminaris.  

The other cochlear nucleus, Nucleus angularis (NA), encodes the amplitudes of spectral components of sounds.  

These cues for sound localization are processed in independent channels originating at nucleus magnocellularis (NM) and Nucleus angularis (NA), the cochlear nuclei.  

Using an antiserum directed against gamma-aminobutyric acid (GABA), the presence of presumed GABAergic neurons is demonstrated in the chicken auditory brainstem nuclei: nucleus laminaris, Nucleus angularis, superior olive, and the ventral nuclei of the lateral lemniscus.  

In monaural subjects Nucleus angularis and nucleus magnocellularis showed faint 2DG uptake on the side contralateral to the intact ear.  

Ascending auditory projections to the nucleus mesencephalicus lateralis pars dorsalis (MLd) were studied in white Leghorn chickens by means of unilateral injections of horseradish peroxidase into the MLd and by injections of tritiated leucine into Nucleus angularis or the combined nucleus magnocellularis and nucleus laminaris. The experiments showed that Nucleus angularis sends an extensive projection to the contralateral MLd and a smaller projection to the rostral pole of the ipsilateral MLd; the lagenar region contributes to these bilateral connections. Nucleus angularis also projects bilaterally to the superior olive and nucleus ventralis lemnisci lateralis and to the contralateral nucleus lemnisci lateralis pars ventralis and dorsal nucleus of the lateral lemniscus. Although several of these findings correspond with auditory connections previously shown in the pigeon brainstem, they differ fundamentally in that we find both Nucleus angularis and nucleus laminaris projecting to different areas of the MLd on both sides of the brain.  

It seems likely that changes in the N1 to P3-4 inter-wave latency reflect changes in evoked activity of second order auditory neurons that are located in the Nucleus angularis and nucleus magnocellularis, and that intensive developmental changes occur in these neurons during the first postnatal week.  

Local auditory evoked potentials (AEPs) in the pigeon were recorded from the nucleus magnocellularis (NM), Nucleus angularis (NA) and Field L with tungsten microelectrodes.  

Anesthetizing the other cochlear nucleus, Nucleus angularis, has the converse effects.  

The primary cochlear nuclei consist of a small Nucleus angularis located at the cerebello-medullary junction and a fairly large nucleus magnocellularis forming a dorsal cap over the cephalic end of the alar eminence.  

A spherical Nucleus angularis and an elongated nuclus magnocellularis together form a column of primary cochlear nuclei in the dorsal alar lamina of the medulla.  

The abnormal movement of neurons in Nucleus angularis to an ectopic position after otocyst ablation suggests that primary auditory afferents may serve to stabilize the position of their target cells within the developing brain..  

A study of silver-stained degeneration pattersn in nucleus magnocellularis (NM) and NL at three intervals following unilateral interruption of the cochlear nerve revealed that by 48 hours after the lesion, degenerating terminals were found only in the ipsilateral Nucleus angularis (NA), NM and lagenar projection areas but not in NL.  

The auditory portion of the VIIIth nerve projects to two nuclei in the dorsomedial medulla-Nucleus angularis and nucleus magnocellularis medialis. These two nuclei together with a third cll group, nucleus magnocellularis lateralis (intercalated between Nucleus angularis and nucleus magnocellularis medialis), have been referred to as the auditory tubercle in previous studies (cf. The axonal degeneration following large lesions of the auditory tubercle and small lesions of Nucleus angularis demonstrated the second order auditory pathways. Fibers leave Nucleus angularis ventrally and travel to the ventral surface of the medulla where they cross the midline and ascend to the midbrain in pathways resembling the trapezoid body and the lateral lemniscus of mammals. Experiments in which horseradish peroxidase injections were made in the torus semicircularis demonstrated that Nucleus angularis is a primary source of second order auditory fibers to the midbrain and, in addition, that two of the lower brainstem targets of the auditory tubercle project to the torus semicircularis.  

The normal anatomy of the three cochlear nuclei in the hen, the nucleus laminaris, the Nucleus angularis and the nucleus magnocellularis is described. The cochlear ganglion cells projecting to the nucleus laminaris are apparently situated in other parts of the ganglion that the cells projecting to the Nucleus angularis and magnocellularis.  

Two well defined cochlear nuclei are found in most lizard families: Nucleus angularis (NA) AND nucleus magnocellularis medialis (NMM).  

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