Fusiform Cell | ScienceGate

The dorsal cochlear nucleus receives input from the auditory nerve and relays acoustic information to the inferior colliculus. Its principal cells receive two systems of inputs. One system through the molecular layer carries multimodal information that is processed through a neuronal circuit that resembles the cerebellum. A second system through the deep layer carries primary auditory nerve input, some of which is relayed through interneurons. The present study reveals the morphology of individual interneurons and their local axonal arbors and how these inhibitory interneurons respond to sound. Vertical cells lie beneath the fusiform cell layer. Their dendritic and axonal arbors are limited to an isofrequency lamina. They give rise to pericellular nests around the base of fusiform cells and their proximal basal dendrites. These cells exhibit an onset-graded response to short tones and have response features defined as type II. They have tuning curves that are closed contours (0 shaped), thresholds ∼27 dB SPL, spontaneous firing rates of ∼0 spikes/s, and they respond weakly or not at all to broadband noise, as described for type II units. Their responses are nonmonotonic functions of intensity with peak responses between 30 and 60 dB SPL. They also show a preference for the high-to-low direction of a frequency sweep. It has been suggested that these circuits may be involved in the processing of spectral cues for the localization of sound sources.

Physiological studies on neurons in the dorsal cochlear nucleus of cat

Journal of Neurophysiology ◽

10.1152/jn.1986.56.2.287 ◽

1986 ◽

Vol 56 (2) ◽

pp. 287-307 ◽

Cited By ~ 88

Author(s):

W. S. Rhode ◽

P. H. Smith

Keyword(s):

Spontaneous Activity ◽

Cochlear Nucleus ◽

Response Pattern ◽

Phase Locking ◽

Molecular Layer ◽

Dorsal Cochlear Nucleus ◽

Fusiform Cell ◽

Graded Response ◽

Temporal Encoding ◽

Onset Response

Results reported here support the conclusion that an individual neuron in the dorsal cochlear nucleus (DCN) can exhibit pauser, buildup, and chopper patterns in response to tone pips. Fusiform cells have been previously identified as the principal cell exhibiting these patterns. Fusiform cells can also exhibit an onset response followed by suppression of spontaneous activity at their characteristic frequency (CF). Off CF only suppression is seen. These neurons are characterized by a restricted excitatory region near threshold. All these cells can exhibit nonmonotonic rate curves, narrow excitatory regions, and inhibitory sidebands. Nonmonotonicity occurred in 34% of pausers, 52% of buildup, 89% of onsets with a graded response, and 50% overall in the DCN cells. Chopper units occur as often as the other types combined in the DCN. Only 14% show nonmonotonic rate curves. Those with high-spontaneous activity also show inhibitory sidebands. Cells with a predominant buildup pattern occur most frequently in the fusiform cell layer, whereas pausers occur throughout the DCN below the molecular layer. Intracellular potentials often reflect the average response pattern. Sharply delimited response areas indicate that these cells may be useful for performing a spectral analysis. These cells show almost no phase locking suggesting that temporal encoding is an unlikely function. It is suggested that the effects of anesthetic on the function of the DCN is not as marked as previously indicated.

Dorsal Cochlear Nucleus Fusiform-cell Plasticity is Altered in Salicylate-induced Tinnitus

Neuroscience ◽

10.1016/j.neuroscience.2018.08.035 ◽

2019 ◽

Vol 407 ◽

pp. 170-181 ◽

Cited By ~ 5

Author(s):

David T. Martel ◽

Thibaut R. Pardo-Garcia ◽

Susan E. Shore

Keyword(s):

Cochlear Nucleus ◽

Dorsal Cochlear Nucleus ◽

Cell Plasticity ◽

Fusiform Cell

Sarcoma undifferentiated (unclassified) fusiform cell type of mesentery: a case report and literature review

Pan African Medical Journal ◽

10.11604/pamj.2020.35.58.17749 ◽

2020 ◽

Vol 35 ◽

Author(s):

Korbi Ibtissem ◽

Korbi Asma ◽

Ennaceur Farouk ◽

Hajji Ahmed ◽

Njima Manel ◽

...

Keyword(s):

Case Report ◽

Literature Review ◽

Cell Type ◽

Fusiform Cell

Cartwheel and superficial stellate cells of the dorsal cochlear nucleus of mice: intracellular recordings in slices

Journal of Neurophysiology ◽

10.1152/jn.1993.69.5.1384 ◽

1993 ◽

Vol 69 (5) ◽

pp. 1384-1397 ◽

Cited By ~ 103

Author(s):

S. Zhang ◽

D. Oertel

Keyword(s):

Cochlear Nucleus ◽

Nerve Root ◽

Action Potentials ◽

Stellate Cell ◽

Molecular Layer ◽

Dorsal Cochlear Nucleus ◽

Fusiform Cell ◽

Parasagittal Plane ◽

Axonal Arbors ◽

Cartwheel Cells

1. Intracellular recordings were made from identified cartwheel and stellate cells in the molecular and fusiform cell layers of the murine dorsal cochlear nucleus (DCN). The aim of the study was to identify and characterize their synaptic inputs and to learn how synaptic inputs and intrinsic electrical properties interact to generate firing patterns. 2. Eight cells labeled by the intracellular injection of biocytin were cartwheel cells. Their axon terminals extended from the deep part of the molecular layer through the fusiform cell layer. Their dendrites extended through the molecular layer and had spines. Both the dendritic and axonal arbors were small, having diameters of approximately 150 microns in the parasagittal plane. 3. When depolarized, cartwheel cells often fired bursts of rapid action potentials superimposed on a slow depolarization. The peaks of action potentials were usually overshooting. Individually occurring action potentials were followed by two afterhyperpolarizations, as in other cells of the DCN. During bursts, action potentials did not have two distinct repolarizing phases. 4. Excitatory postsynaptic potentials (EPSPs) were recorded from cartwheel cells spontaneously and after shocks to the nerve root or to the ventral cochlear nucleus (VCN). The EPSPs rose slowly. When they were suprathreshold they evoked action potentials singly or in bursts. EPSPs evoked by shocks to the nerve root or to the VCN had long latencies, the rise of EPSPs beginning between 5 and 10 ms after the shock. No inhibitory synaptic potentials, either spontaneous or driven with electrical stimulation, were detected in cells whose resting potentials were between -50 and -70 mV. 5. The locations from which excitatory input can be driven electrically are consistent with cartwheel cells receiving excitatory synaptic input from granule cells. 6. One labeled cell was a superficial stellate cell. It had smooth, straight dendrites that radiated parallel to the layers of the DCN; its axonal arbor was also planar and was restricted to the molecular layer. Both the dendritic and axonal arbors of this stellate cell were large, > 500 microns diam in the parasagittal plane. 7. The superficial stellate cell fired trains of action potentials at regular intervals that, like other cells of the DCN, were overshooting and were followed by double undershoots. 8. Shocks to the nerve root and to the surface of the VCN evoked EPSPs after 3.5 and 2 ms, respectively, in the superficial stellate cell. Chemical stimulation of the VCN also evoked excitation. No inhibitory synaptic input, spontaneous or driven, was detected.

Acoustic and Current-Pulse Responses of Identified Neurons in the Dorsal Cochlear Nucleus of Unanesthetized, Decerebrate Gerbils

Journal of Neurophysiology ◽

10.1152/jn.1999.82.6.3434 ◽

1999 ◽

Vol 82 (6) ◽

pp. 3434-3457 ◽

Cited By ~ 38

Author(s):

Jiang Ding ◽

Thane E. Benson ◽

Herbert F. Voigt

Keyword(s):

Cell Morphology ◽

Giant Cells ◽

Dorsal Cochlear Nucleus ◽

Membrane Properties ◽

Type I ◽

Fusiform Cell ◽

Response Properties ◽

Type Iii ◽

Acoustic Responses ◽

Cartwheel Cells

In an effort to establish relationships between cell physiology and morphology in the dorsal cochlear nucleus (DCN), intracellular single-unit recording and marking experiments were conducted on decerebrate gerbils using horseradish peroxidase (HRP)- or neurobiotin-filled micropipettes. Intracellular responses to acoustic (tone and broadband noise bursts) and electric current-pulse stimuli were recorded and associated with cell morphology. Units were classified according to the response map scheme (type I to type V). Results from 19 identified neurons, including 13 fusiform cells, 2 giant cells, and 4 cartwheel cells, reveal correlations between cell morphology of these neurons and their acoustic responses. Most fusiform cells (8/13) are associated with type III unit response properties. A subset of fusiform cells was type I/III units (2), type III-i units (2), and a type IV-T unit. The giant cells were associated with type IV-i unit response properties. Cartwheel cells all had weak acoustic responses that were difficult to classify. Some measures of membrane properties also were correlated with cell morphology but to a lesser degree. Giant cells and all but one fusiform cell fired only simple action potentials (APs), whereas all cartwheel cells discharged complex APs. Giant and fusiform cells all had monotonic rate versus current level curves, whereas cartwheel cells had nonmonotonic curves. This implies that inhibitory acoustic responses, resulting in nonmonotonic rate versus sound level curves, are due to local inhibitory interactions rather than strictly to membrane properties. A complex-spiking fusiform cell with type III unit properties suggests that cartwheel cells are not the only complex-spiking cells in DCN. The diverse response properties of the DCN′s fusiform cells suggests that they are very sensitive to the specific complement of excitatory and inhibitory inputs they receive.

Properties of GABAergic Neurons in the Rostral Solitary Tract Nucleus in Mice

Journal of Neurophysiology ◽

10.1152/jn.00971.2009 ◽

2010 ◽

Vol 103 (6) ◽

pp. 3205-3218 ◽

Cited By ~ 23

Author(s):

Min Wang ◽

Robert M. Bradley

Keyword(s):

Green Fluorescent Protein ◽

Fluorescent Protein ◽

Projection Neurons ◽

Solitary Tract ◽

Fusiform Cell ◽

Tonic Firing ◽

Initial Burst ◽

Burst Neurons ◽

Taste Processing ◽

Green Fluorescent

The rostral nucleus of the solitary tract (rNST) plays a pivotal role in taste processing. The rNST contains projection neurons and interneurons that differ in morphology and intrinsic membrane properties. Although characteristics of the projection neurons have been detailed, similar information is lacking on the interneurons. We determined the intrinsic properties of the rNST GABAergic interneurons using a transgenic mouse model that expresses enhanced green fluorescent protein under the control of a GAD67 promoter. Glutamic acid decarboxylase–green fluorescent protein (GAD67–GFP) neurons were distributed throughout the rNST but were concentrated in the ventral subdivision with minimal interaction with the terminal field of the afferent input. Furthermore, the density of the GAD67–GFP neurons decreased in more rostral areas of rNST. In whole cell recordings, GAD67–GFP neurons responded with either an initial burst (73%), tonic (18%), or irregular (9%) discharge pattern of action potentials (APs) in response to membrane depolarization. These three groups also differed in passive and AP characteristics. Initial burst neurons had small ovoid or fusiform cell bodies, whereas tonic firing neurons had large multipolar or fusiform cell bodies. Irregular firing neurons had larger spherical soma. Some of the initial burst and tonic firing neurons were also spontaneously active. The GAD67–GFP neurons could also be categorized in subgroups based on colocalization with somatostatin and parvalbumin immunolabeling. Initial burst neurons would transmit the early dynamic portion of the encoded sensory stimuli, whereas tonic firing neurons could respond to both dynamic and static components of the sensory input, suggesting different roles for GAD67–GFP neurons in taste processing.

A computational model with ionic conductances for the fusiform cell of the dorsal cochlear nucleus

The Journal of the Acoustical Society of America ◽

10.1121/1.410228 ◽

1994 ◽

Vol 96 (3) ◽

pp. 1501-1514 ◽

Cited By ~ 7

Author(s):

D. O. Kim ◽

S. Ghoshal ◽

S. L. Khant ◽

K. Parham

Keyword(s):

Computational Model ◽

Cochlear Nucleus ◽

Dorsal Cochlear Nucleus ◽

Fusiform Cell ◽

Ionic Conductances

Intracellularly Labeled Fusiform Cells in Dorsal Cochlear Nucleus of the Gerbil. II. Comparison of Physiology and Anatomy

Journal of Neurophysiology ◽

10.1152/jn.2002.87.5.2520 ◽

2002 ◽

Vol 87 (5) ◽

pp. 2520-2530 ◽

Cited By ~ 20

Author(s):

Kenneth E. Hancock ◽

Herbert F. Voigt

Keyword(s):

Cochlear Nucleus ◽

Input Resistance ◽

Apical Dendrite ◽

Broadband Noise ◽

Dorsal Cochlear Nucleus ◽

Cell Physiology ◽

Spatial Gradient ◽

Fusiform Cell ◽

Spontaneous Rate ◽

Basal Dendrites

Fusiform cells represent the major class of dorsal cochlear nucleus (DCN) projection neuron. Although much is understood about their physiology and anatomy, there remain unexplored issues with important functional implications. These include interspecies differences in DCN physiology and the nature of the cell-to-cell variations in fusiform cell physiology. To address these issues, a quantitative examination was made of the physiology and anatomy of 17 fusiform cells from a companion study. The results suggest that the basal dendrites of gerbil fusiform cells may be electrotonically more compact than those of the cat. This relative decrease in the filtering of excitatory inputs might account for the lower incidence of type IV units in that species. These data also suggest that the gerbil DCN lacks the high-frequency specialization described in the cat, because the tonotopic arrangement of the gerbil fusiform cells quantitatively matches the place-frequency map for the gerbil cochlea. Certain physiological properties have anatomical correlates. First, the basal dendrites of low spontaneous rate cells are directed away from the soma only in the caudal direction, while the high spontaneous rate cells have basal dendrites extending rostrally and caudally. Second, input resistance was dominated by the surface area of the apical dendrite. Third, the discharge pattern was correlated with apical dendrite orientation. Finally, there was a spatial gradient of sensitivity to broadband noise organized at least partially within an isofrequency axis. Such trends indicate that neighboring fusiform cells are endowed with different signal processing capabilities.