Evidence for a GABAergic Projection from the Dorsal Nucleus of the Lateral Lemniscus to the Inferior Colliculus

Shneiderman, Amiram; Chase, Maretta; Rockwood, Julia M.; Benson, Christina G.; Potashner, S.J.

doi:10.1111/j.1471-4159.1993.tb05824.x

Cited by 76 publications

(49 citation statements)

References 55 publications

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“…Type V units seem less likely to provide the INH input because they show broad tuning at high levels and exist within a restricted range of BFs . External sources of the INH inputs include GABAergic projections from the dorsal nucleus of the lateral lemniscus (Shneiderman et al 1993). …”

Section: Candidate Inputs For the Type O Circuitrymentioning

confidence: 99%

Auditory Processing of Spectral Cues for Sound Localization in the Inferior Colliculus

Davis

Ramachandran

May

2003

JARO - Journal of the Association for Research in Otolaryngolog

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The head-related transfer function (HRTF) of the cat adds directionally dependent energy minima to the amplitude spectrum of complex sounds. These spectral notches are a principal cue for the localization of sound source elevation. Physiological evidence suggests that the dorsal cochlear nucleus (DCN) plays a critical role in the brainstem processing of this directional feature. Type O units in the central nucleus of the inferior colliculus (ICC) are a primary target of ascending DCN projections and, therefore, may represent midbrain specializations for the auditory processing of spectral cues for sound localization. Behavioral studies confirm a loss of sound orientation accuracy when DCN projections to the inferior colliculus are surgically lesioned. This study used simple analogs of HRTF notches to characterize single-unit response patterns in the ICC of decerebrate cats that may contribute to the directional sensitivity of the brain's spectral processing pathways. Manipulations of notch frequency and bandwidth demonstrated frequency-specific excitatory responses that have the capacity to encode HRTF-based cues for sound source location. These response patterns were limited to type O units in the ICC and have not been observed for the projection neurons of the DCN. The unique spectral integration properties of type O units suggest that DCN influences are transformed into a more selective representation of sound source location by a local convergence of wideband excitatory and frequency-tuned inhibitory inputs.

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Section: Candidate Inputs For the Type O Circuitrymentioning

confidence: 99%

Auditory Processing of Spectral Cues for Sound Localization in the Inferior Colliculus

Davis

Ramachandran

May

2003

JARO - Journal of the Association for Research in Otolaryngolog

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“…Major excitatory synaptic inputs to ICC neurons come from the dorsal and ventral cochlear nuclei and the medial and lateral superior olive. At the same time, ICC neurons receive ascending inhibitory inputs from the lateral superior olive and the nuclei of the lateral lemniscus (Adams 1979;Saint Marie et al 1989;Shneiderman et al 1993;Riquelme et al 2001). This combination of excitatory and inhibitory inputs ascending through the lateral lemniscus is one of several unique and important characteristics of the ICC.…”

Section: Introductionmentioning

confidence: 99%

Neuronal Responses to Lemniscal Stimulation in Laminar Brain Slices of the Inferior Colliculus

Sivaramakrishnan

Oliver

2005

JARO

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The central nucleus of the inferior colliculus (ICC) receives inputs from all parts of the auditory brainstem and transmits the information to the forebrain. Fibrodendritic laminae of the ICC provide a structural basis for a tonotopic organization, and the interaction of inputs within a single layer is important for ICC processing. Transverse slice planes of the ICC sever the layers and many of the ascending axons that enter through the lateral lemniscus. Consequently, the activity initiated within a lamina by a pure lemniscal stimulus is not well characterized. Here, we use a slice plane that maintains the integrity of the laminae in ICC and allows the axons in the lateral lemniscus to be stimulated at a distance from the ICC. We examined both the postsynaptic currents and potentials of the same neurons to lemniscal stimuli in this laminar brain slice. Our main finding is that lemniscal stimulation evokes prolonged synaptic potentials in ICC neurons. Synaptic potential amplitudes and durations increase with lemniscal shock strength. In õ50% of ICC neurons, the postsynaptic potential is equal in duration to the postsynaptic current, whereas in the remaining neurons it is three to four times longer. Synaptic responses to single shocks or shock trains exhibit plateau potentials that enable sustained firing in ICC neurons. Plateau potentials are evoked by N-methyl-D-aspartate (NMDA) receptor activation, and their amplitudes and durations are regulated by both NMDA-R and gamma-aminobutyric acid A (GABA A )-R activation. These data suggest that in the intact laminae of the ICC, lemniscal inputs initiate sustained firing through monosynaptic and polysynaptic NMDA-mediated synapses regulated by GABA A synapses.

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“…Together these observations suggest that a labeled band of DNLL input together with the adjacent unlabeled space is likely to form a layer composed of ipsilateral and contralateral projections. DNLL neurons utilize the neurotransmitter GABA and make symmetric synaptic contacts with the soma and proximal dendrites of IC neurons (Brunso-Bechtold et al, 1981;Adams and Mugnaini, 1984;Shneiderman et al, 1988Shneiderman et al, ,1993Bajo et al, 1993;Merchan et al, 1994;Gonzalez-Hernandez et al, 1996;Kelly and Li, 1997;Chen et al, 1999;van Adel et al, 1999). Although much more is known about the developmental mechanisms of glutamatergic circuit formation, important progress has been made in understanding the development of inhibitory circuits in the auditory brainstem such as those in the SOC (Kandler, 2004;Kandler and Gillespie, 2005).…”

Section: Activity-dependent Changes In Developing Circuitsmentioning

confidence: 99%

Unilateral cochlear ablation before hearing onset disrupts the maintenance of dorsal nucleus of the lateral lemniscus projection patterns in the rat inferior colliculus

2006

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During postnatal development, ascending and descending auditory inputs converge to form fibrodendritic layers within the central nucleus of the inferior colliculus (IC). Before the onset of hearing, specific combinations of inputs segregate into bands separated by interband spaces. These bands may define functional zones within the IC. Previous studies in our laboratory have shown that unilateral or bilateral cochlear ablation at postnatal day 2 (P2) disrupts the development of afferent bands from the dorsal nucleus of the lateral lemniscus (DNLL) to the IC. These results suggest that spontaneous activity propagated from the cochlea is required for the segregation of afferent bands within the developing IC. To test if spontaneous activity from the cochlea also may be required to maintain segregated bands of DNLL input, we performed cochlear ablations in rat pups at P9, after DNLL bands already are established. All animals were killed at P12 and glass pins coated with carbocyanine dye, DiI (1,1′-dioctodecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate), subsequently were placed in the commissure of Probst to label the crossed projections from both DNLLs. When compared with surgical controls, experimental results showed a similar pattern of DNLL bands in the IC contralateral to the ablated cochlea, but a disruption of DNLL bands in the IC ipsilateral to the cochlear ablation. The present results suggest that cochlear ablation after DNLL bands have formed may affect the maintenance of banded DNLL projections within the central nucleus of the IC. KeywordsDNLL; DiI; development; afferent bands; GABA; deafferentation The central nucleus of the inferior colliculus (IC) is composed of a series of cochleotopically ordered layers that preserve frequency-specific processing of various auditory features. Multiple auditory nuclei target the IC and terminate in afferent compartments along these cochleotopic layers (Oliver and Shneiderman, 1989b). It is likely that these afferent compartments within the IC create an intrinsic organization capable of integrating inputs from different auditory nuclei (Oliver and Shneiderman, 1989a;Cant and Benson, 2006).A banded organization of afferent projections to the IC develops quite early, in fact, well before auditory experience could shape functioning synaptic circuits. For example, crossed projections from the dorsal nucleus of the lateral lemniscus (DNLL) to the central nucleus of the IC have organized into bands about one week before hearing onset in rat (Gabriele et al.,

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Evidence for a GABAergic Projection from the Dorsal Nucleus of the Lateral Lemniscus to the Inferior Colliculus

Cited by 76 publications

References 55 publications

Auditory Processing of Spectral Cues for Sound Localization in the Inferior Colliculus

Auditory Processing of Spectral Cues for Sound Localization in the Inferior Colliculus

Neuronal Responses to Lemniscal Stimulation in Laminar Brain Slices of the Inferior Colliculus

Unilateral cochlear ablation before hearing onset disrupts the maintenance of dorsal nucleus of the lateral lemniscus projection patterns in the rat inferior colliculus

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