Inhibition in the medial geniculate body of the cat

Aitkin, Lindsay; Dunlop, Colin W.

doi:10.1007/bf00236108

Cited by 85 publications

(27 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alternatively, if the maskers produced long-lasting inhibition of at least several hundred milliseconds, then the backward masker presented in the first observation interval might reduce the neural response to the target presented in the second interval. There is clear evidence for persistence over an interval of more than 100 ms and for inhibition for several seconds in the medial geniculate body and in primary auditory cortex [70], [81], [82], but most studies suggest that the two phenomena do not occur at earlier processing stages (for an in-depth discussion see [28]). …”

Section: Discussionmentioning

confidence: 99%

Sequential Grouping Modulates the Effect of Non-Simultaneous Masking on Auditory Intensity Resolution

Oberfeld

Stahn

2012

PLoS ONE

View full text Add to dashboard Cite

The presence of non-simultaneous maskers can result in strong impairment in auditory intensity resolution relative to a condition without maskers, and causes a complex pattern of effects that is difficult to explain on the basis of peripheral processing. We suggest that the failure of selective attention to the target tones is a useful framework for understanding these effects. Two experiments tested the hypothesis that the sequential grouping of the targets and the maskers into separate auditory objects facilitates selective attention and therefore reduces the masker-induced impairment in intensity resolution. In Experiment 1, a condition favoring the processing of the maskers and the targets as two separate auditory objects due to grouping by temporal proximity was contrasted with the usual forward masking setting where the masker and the target presented within each observation interval of the two-interval task can be expected to be grouped together. As expected, the former condition resulted in a significantly smaller masker-induced elevation of the intensity difference limens (DLs). In Experiment 2, embedding the targets in an isochronous sequence of maskers led to a significantly smaller DL-elevation than control conditions not favoring the perception of the maskers as a separate auditory stream. The observed effects of grouping are compatible with the assumption that a precise representation of target intensity is available at the decision stage, but that this information is used only in a suboptimal fashion due to limitations of selective attention. The data can be explained within a framework of object-based attention. The results impose constraints on physiological models of intensity discrimination. We discuss candidate structures for physiological correlates of the psychophysical data.

show abstract

Section: Discussionmentioning

confidence: 99%

Sequential Grouping Modulates the Effect of Non-Simultaneous Masking on Auditory Intensity Resolution

Oberfeld

Stahn

2012

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…The smaller GABAergic TT cells presumably have slower conduction velocities, and consequently their postsynaptic effects would be expected to occur later. Among the candidate processes that inhibition might affect are the shaping of spectral cues (39), modulating intensity-dependent inhibition (40), enhancing selectivity for species-specific vocalizations (41), altering the spontaneous discharge of thalamocortical cells (26), or affecting the long term excitability of large populations of neurons (42). Neither the large nor the small GABAergic TT cells are involved in early coding in the temporal domain or in the establishment of binaural properties, both of which are represented robustly at prethalamic levels (43).…”

Section: Discussionmentioning

confidence: 99%

GABAergic feedforward projections from the inferior colliculus to the medial geniculate body.

Winer

Marie

Larue

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

166

111

View full text Add to dashboard Cite

A novel and robust projection from y-aminobutyric acid-containing (GABAergic) inferior colliculus neurons to the medial geniculate body (MGB) was discovered in the cat using axoplasmic transport methods combined with immunocytochemistry. This input travels with the classical inferior colliculus projection to the MGB, and it is a direct ascending GABAergic pathway to the sensory thalamus that may be inhibitory. This bilateral projection constitutes 10-30% of the neurons in the auditory tectothalamic system. Studies by others have shown that comparable input to the corresponding thalamic visual or somesthetic nuclei is absent. This suggests that monosynaptic inhibition or disinhibition is a prominent feature in the MGB and that differences in neural circuitry distinguish it from its thalamic visual and somesthetic counterparts.The thalamus is the gateway controlling the flow of sensory information reaching the cerebral cortex (1). The consensus is that input ascending to the primary thalamic nuclei for hearing (2), vision (3), and somesthesis (4) is entirely excitatory. We describe here a prominent and unexpected projection from y-aminobutyric acid-containing (GABAergic) cells in the inferior colliculus (IC) to the medial geniculate body (MGB) in the auditory tectothalamic (TT) pathway that constitutes an exception to this principle. This suggests that there is a convergence of classical excitatory and putatively inhibitory projections within the MGB and that an ascending pathway considered as neurochemically unitary in fact contains more than one channel. This striking difference in feedforward input between the auditory thalamus and other thalamic sensory nuclei is surprising since each has similar structural and intrinsic features (5-7), shared physiological properties (8-10), analogous cortical projection patterns (11-13), and a closely related neurochemical organization (14, 15). The present results suggest that, despite these parallels, there must be differences in circuitry and information processing regimes within the sensory thalamus.with isoflurane at a level that suppressed all nociceptive reflexes. All experimental procedures followed the applicable and approved institutional animal care and use protocols. Four unilateral penetrations were made using stereotaxic coordinates to target specific nuclei in various subdivisions. A total of seven, 50-nl deposits were made at 500-,um intervals along a track with a glass micropipet; the net volume was -1.5 ,lI.The animal was reanesthetized 3 days later and perfused with PBS followed by 2% paraformaldehyde and 3% glutaraldehyde in 0.12 M PB. Vibratome sections, 50-,m-thick, were collected in 0.1 M PB and placed in blocking serum (5% normal goat serum) for 60 min. Tissue was incubated overnight at 4°C in rabbit-anti-GABA (Incstar, Stillwater, MN) diluted 1:5000 and then reacted using avidin-biotin immunoperoxidase (Vectastain, Vector Laboratories, Burlingame, CA) with diaminobenzidine as the chromagen. WAHG labeling was intensified with silver (IntenSE-M...

show abstract

“…(1) Stimulation of collicular brachium elicits a fast, monosynaptic excitatory synaptic potential in both ventral lemniscal and dorsal non-lemniscal MGB. (2) (Aitkin & Dunlop, 1969;Calford, 1983). The detailed membrane mechanisms underlying response duality among MGv and MGd neurones, however, require further study.…”

Section: Discussionmentioning

confidence: 99%

Lemniscal and non‐lemniscal synaptic transmission in rat auditory thalamus.

Senatorov

Mooney

1994

The Journal of Physiology

View full text Add to dashboard Cite

1. The central auditory pathway linking the inferior colliculus (IC) and the medial geniculate body (MGB) of the thalamus consists of a segregated ventral lemniscal and dorsal non-lemniscal projection whose synaptic transmission mechanisms remain unknown. Extracellular and intracellular recordings combined with axonal tract tracing and cell staining were made from lemniscal and non-lemniscal divisions of adult rat MGB maintained acutely in in vitro explants containing parallel tectothalamic projections. 2. Biocytin deposition within the brachium of the IC revealed dense axonal fibres projecting to the MGB. Thin axonal terminals were found throughout the ventral (MGv) and dorsal (MGd) divisions of the MGB. Bushy cells with tufted or bitufted dendritic branches were primarily found in the MGv. In the MGd, cells were mainly seen as stellate neurones having a radiate dendritic arbor. 3. Electrical stimulation of the brachium of IC invariably elicits fast, excitatory synaptic potentials in both MGv and MGd cells. The evoked responses occurred monosynaptically and were exclusively mediated by glutamate acting on both N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Non-lemniscal MGd neurones recorded extracellularly exhibited a strong tendency to discharge in bursts in response to brachium stimulation. In contrast, a large proportion of ventral lemniscal cells tended to discharge in single or dual spikes. Intracellularly, MGd cells, but not MGv cells, showed a predominant, slow synaptic potential mediated by NMDA receptors. 4. It is concluded that the central auditory circuitry linking the tectum and the thalamus is connected monosynaptically via glutamatergic synapses. Lemniscal and non-lemniscal thalamic neurones possess distinct response properties which cannot be accounted for by a differential transmitter system or polysynaptic delays as postulated previously.

show abstract

Inhibition in the medial geniculate body of the cat

Cited by 85 publications

References 18 publications

Sequential Grouping Modulates the Effect of Non-Simultaneous Masking on Auditory Intensity Resolution

Sequential Grouping Modulates the Effect of Non-Simultaneous Masking on Auditory Intensity Resolution

GABAergic feedforward projections from the inferior colliculus to the medial geniculate body.

Lemniscal and non‐lemniscal synaptic transmission in rat auditory thalamus.

Contact Info

Product

Resources

About