Pharmacology of the Inferior Colliculus

Kelly, Jack B.; Caspary, Donald M.

doi:10.1007/0-387-27083-3_9

Cited by 41 publications

(49 citation statements)

References 159 publications

(214 reference statements)

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“…Finally, the GADonly subtype includes many medium and small cells. The possibility of more than four GABAergic subtypes is consistent with the numerous roles of GABA in the IC (Kelly and Caspary, 2005;Pollak, 2013) and the recognition of many GABAergic cell types in other brain areas (Lawrence, 2008;Kubota, 2014;LovettBarron and Losonczy, 2014). Nonetheless, we believe that these size categories should be considered putative until other characteristics (for example, axonal projection patterns or other molecular markers) corroborate the distinctions.…”

Section: Identification Of Gabaergic Subtypesmentioning

confidence: 70%

“…In the inferior colliculus (IC), a major processing center of the auditory system, approximately one-quarter of neurons is GABAergic (Merchán et al, 2005). These cells are important in both ascending projections from the IC and local inhibition within the IC (Peruzzi et al, 1997;Sivaramakrishnan et al, 2004;Kelly and Caspary, 2005;Pollak, 2013). The extent to which GABAergic IC cells comprise subtypes remains unclear.…”

Section: Introductionmentioning

confidence: 99%

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Extracellular Molecular Markers and Soma Size of Inhibitory Neurons: Evidence for Four Subtypes of GABAergic Cells in the Inferior Colliculus

et al. 2016

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Inhibition plays an important role in shaping responses to stimuli throughout the CNS, including in the inferior colliculus (IC), a major hub in both ascending and descending auditory pathways. Subdividing GABAergic cells has furthered the understanding of inhibition in many brain areas, most notably in the cerebral cortex. Here, we seek the same understanding of subcortical inhibitory cell types by combining staining for two types of extracellular markers-perineuronal nets (PNs) and perisomatic rings of terminals expressing vesicular glutamate transporter 2 (VGLUT2) -to subdivide IC GABAergic cells in adult guinea pigs. We found four distinct groups of GABAergic cells in the IC: (1) those with both a PN and a VGLUT2 ring; (2) those with only a PN; (3) those with only a VGLUT2 ring; and (4) those with neither marker. In addition, these four GABAergic subtypes differ in their soma size and distribution among IC subdivisions. Functionally, the presence or absence of VGLUT2 rings indicates differences in inputs, whereas the presence or absence of PNs indicates different potential for plasticity and temporal processing. We conclude that these markers distinguish four GABAergic subtypes that almost certainly serve different roles in the processing of auditory stimuli within the IC.

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Section: Identification Of Gabaergic Subtypesmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Extracellular Molecular Markers and Soma Size of Inhibitory Neurons: Evidence for Four Subtypes of GABAergic Cells in the Inferior Colliculus

et al. 2016

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“…Based on this explanation, ICC stimulation thresholds may be even lower than those presented in this paper. There is also evidence that the ICC consists of a complex network of excitatory and inhibitory neural connections (Kelly and Caspary 2005). Thus it is possible that single-pulse stimulation of certain ICC regions may predominantly activate inhibitory neurons or may not properly activate these complex circuits, and only with higher stimulus levels is activity finally elicited in A1.…”

Section: Discussionmentioning

confidence: 99%

Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Lim¹,

Anderson²

2007

Journal of Neurophysiology

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. Auditory cortical responses to electrical stimulation of the inferior colliculus: implications for an auditory midbrain implant. J Neurophysiol 96: 975-988, 2006. First published May 24, 2006 doi:10.1152/jn.01112.2005. The success and limitations of cochlear implants (CIs) along with recent advances in deep brain stimulation and neural engineering have motivated the development of a central auditory prosthesis. In this study, we investigated the effects of electrical stimulation of the inferior colliculus central nucleus (ICC) on primary auditory cortex (A1) activity to determine the potential benefits of an auditory midbrain implant (AMI). We recorded multiunit activity in A1 of ketamine-anesthetized guinea pigs in response to single-pulse (200 s/phase) monopolar stimulation of the ICC using multisite silicon-substrate probes. We then compared measures of threshold, dynamic range, and tonotopic spread of activation for ICC stimulation with that of published data for CI stimulation. Our results showed that compared with cochlear stimulation, ICC stimulation achieved: 1) thresholds about 8 dB lower; 2) dynamic ranges Ն4 dB greater; and 3) more localized, frequency-specific activation, even though frequency specificity was partially lost at higher stimulus levels for low-frequency ICC regions. Our results also showed that stimulation of rostral ICC regions elicited lower thresholds but with greater activation spread along the tonotopic gradient of A1 than did stimulation of more caudal regions. These results suggest that an AMI may improve frequency and level coding with lower energy requirements compared with CIs. However, a trade-off between lower perceptual thresholds and better frequency discrimination may exist that depends on location of stimulation along the caudorostral dimension of the ICC. Overall, this study provides the foundation for future AMI research and development.

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“…IC circuits utilizing both GABAergic and glycinergic inhibition have been shown to be important in coding selective communication calls in animals and are critically involved in delay circuits in bats (Yan and Suga, 1996;Portfors and Wenstrup, 2001;Klug et al, 2002). The IC receives excitatory glutamatergic inputs directly from the DCN as well as a major ascending projection from the SOC (for a review, see Kelly and Caspary, 2005). Extrinsic GABAergic projections to the IC arise bilaterally from the dorsal nuclei of the lateral lemniscus, while glycinergic inputs originate from the ventral nucleus of the lateral lemniscus and the LSO.…”

Section: Inferior Colliculusmentioning

confidence: 99%

Inhibitory neurotransmission, plasticity and aging in the mammalian central auditory system

Caspary

Ling

Turner

et al. 2008

Journal of Experimental Biology

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436

355

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SummaryAging and acoustic trauma may result in partial peripheral deafferentation in the central auditory pathway of the mammalian brain. In accord with homeostatic plasticity, loss of sensory input results in a change in pre-and postsynaptic GABAergic and glycinergic inhibitory neurotransmission. As seen in development, age-related changes may be activity dependent. Age-related presynaptic changes in the cochlear nucleus include reduced glycine levels, while in the auditory midbrain and cortex, GABA synthesis and release are altered. Presumably, in response to age-related decreases in presynaptic release of inhibitory neurotransmitters, there are age-related postsynaptic subunit changes in the composition of the glycine (GlyR) and GABA A (GABA A R) receptors. Age-related changes in the subunit makeup of inhibitory pentameric receptor constructs result in altered pharmacological and physiological responses consistent with a net down-regulation of functional inhibition. Age-related functional changes associated with glycine neurotransmission in dorsal cochlear nucleus (DCN) include altered intensity and temporal coding by DCN projection neurons. Loss of synaptic inhibition in the superior olivary complex (SOC) and the inferior colliculus (IC) likely affect the ability of aged animals to localize sounds in their natural environment. Age-related postsynaptic GABA A R changes in IC and primary auditory cortex (A1) involve changes in the subunit makeup of GABA A Rs. In turn, these changes cause age-related changes in the pharmacology and response properties of neurons in IC and A1 circuits, which collectively may affect temporal processing and response reliability. Findings of age-related inhibitory changes within mammalian auditory circuits are similar to age and deafferentation plasticity changes observed in other sensory systems. Although few studies have examined sensory aging in the wild, these age-related changes would likely compromise an animal's ability to avoid predation or to be a successful predator in their natural environment.Key words: aging, central auditory system, GABA A receptor, glycine receptor, inhibitory neurotransmission, plasticity. THE JOURNAL OF EXPERIMENTAL BIOLOGY 1782important in determining the location of sound, echolocation and extracting information from voiced and unvoiced communication signals (Carr et al., 1986;Portfors and Wenstrup, 2001).The complex processing that occurs at the level of the MGB and the A1 is beyond the scope of the present review. Coding in the auditory cortex has been recently reviewed (Wang, 2007;Rauschecker, 2005). As seen in the visual cortex, in the auditory cortex, acoustically complex hierarchical analysis has been described for awake-behaving primates (Rauschecker, 2005;Steinschneider et al., 2008). A1 has been shown to undergo agerelated plastic changes, including down-regulation of inhibitory coding, similar to that observed at lower levels of the auditory pathway and in visual cortex. Similar to age-related changes, activity-dependant changes have be...

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Pharmacology of the Inferior Colliculus

Cited by 41 publications

References 159 publications

Extracellular Molecular Markers and Soma Size of Inhibitory Neurons: Evidence for Four Subtypes of GABAergic Cells in the Inferior Colliculus

Extracellular Molecular Markers and Soma Size of Inhibitory Neurons: Evidence for Four Subtypes of GABAergic Cells in the Inferior Colliculus

Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Inhibitory neurotransmission, plasticity and aging in the mammalian central auditory system

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