The role of the inferior colliculus in a genetic model of audiogenic seizures

The role of the inferior colliculus in a genetic model of audiogenic seizures Ribak Morin

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The role of the inferior colliculus in a genetic model of audiogenic seizures 1995 Anatomy and Embryology 10.1007/bf00534681 ribak1995-the-role-of-the-inferior-colliculu ribak1995-the-role-of-the-inferior-colliculu.txt, the project's staged copy a221e823f29755f5517fb9d86a9456bf6f261328 open-access neuroscience

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them mechanism Quotation withheld because this record is not cleared for redistribution. audiogenic seizures Quotation withheld because this record is not cleared for redistribution. review review Quotation withheld because this record is not cleared for redistribution. mechanisms GABA is taken back up more efficiently in the ICCN of GEPR-9s, so less GABA remains in the synapse to reach postsynaptic GABA receptors, inhibition is weakened, and seizures start in that nucleus despite the extra GABAergic neurons. Quotation withheld because this record is not cleared for redistribution. mechanisms Alternatively, excitation is enhanced in the ICCN through overexpression of glutamate receptors, which would fit the raised glutamate and aspartate levels measured there. Quotation withheld because this record is not cleared for redistribution. mechanisms Seizure activity initiated in the ICCN is carried out of the colliculus along the bilateral ICCN-to-external-nucleus projection and onward to the superior colliculus and pontine reticular formation. Quotation withheld because this record is not cleared for redistribution. How the surplus of small GABAergic neurons produces the observed pharmacological defects at GABAergic synapses is unresolved. what this limits: the causal link between the cell-count finding and the pharmacology: IT REMAINS TO BE RESOLVED HOW THE INCREASE IN SMALL GABAergic NEURONS IN THE ICCN IS RESPONSIBLE FOR THE KNOWN PHARMACOLOGICAL DEFECTS OBSERVED AT GABAergic SYNAPSES Quotation withheld because this record is not cleared for redistribution. The contribution of other brainstem structures to seizure propagation has not been established. what this limits: the seizure-propagation account: FURTHER STUDIES ARE REQUIRED TO DETERMINE THE RELATIONSHIP OF THESE OTHER STRUCTURES TO THE PROPAGATION OF SEIZURE ACTIVITY Quotation withheld because this record is not cleared for redistribution. The two candidate mechanisms offered for seizure initiation remain untested. what this limits: the initiation mechanism: TWO HYPOTHESES WILL BE TESTED IN FUTURE STUDIES: (1) INCREASED GABA UPTAKE, AND (2) INCREASED GLUTAMATE RECEPTOR EXPRESSION Quotation withheld because this record is not cleared for redistribution. The animal strains are named by their assigned score on a 0-9 behavioural rating scale. what this limits: any comparison between GEPR strains: a strain displaying moderate seizures with an assigned seizure score of 3 is designated GEPR-3 and used as an animal model, so the strain name is a position on the rating scale Quotation withheld because this record is not cleared for redistribution. The rating scale's levels are defined by observed behaviour, and the paper prints them. what this limits: any seizure score quoted from this literature: the seizures are scored on a 0-9 scale with 0 being no seizure and 9 a fit of wild running with an accompanying tonic seizure Quotation withheld because this record is not cleared for redistribution. The cell-type census of the region is stated as a suggestion from these results. what this limits: the claim that four of six ICCN cell types are GABAergic: the authors give it as what these results suggest Quotation withheld because this record is not cleared for redistribution. GEPR-3 GEPR-3 Quotation withheld because this record is not cleared for redistribution. seizure score seizure score Quotation withheld because this record is not cleared for redistribution. animal model animal model Quotation withheld because this record is not cleared for redistribution. Genetically epilepsy-prone rats Genetically epilepsy-prone rats Quotation withheld because this record is not cleared for redistribution. GABAergic inhibitory neurons GABAergic inhibitory neurons Quotation withheld because this record is not cleared for redistribution. GEPR-3 - A STRAIN NAME THAT IS A SCALE SCORE: a rat strain showing moderate seizures is assigned a seizure score of 3 and thereby designated GEPR-3, so a behavioural rating becomes a strain name and then a fixed kind of animal; a later comparison of GEPR-3 with GEPR-9 compares two points on an ordinal scale that have been reified into two categories Quotation withheld because this record is not cleared for redistribution. the seizure score - A 0-9 ORDINAL WITH BEHAVIOURAL ENDPOINTS: 0 is no seizure and 9 is one fit of wild running with an accompanying tonic seizure, so the scale is anchored in observable behaviour and the number that travels in a strain name is a rank on it Quotation withheld because this record is not cleared for redistribution. the ICCN cell-type count - OFFERED AS A SUGGESTION: the authors write that these results SUGGEST four of the six major cell types are GABAergic inhibitory neurons, so the census is a reading of the data rather than an enumeration Quotation withheld because this record is not cleared for redistribution. builds-on → Faingold et al. (1986a) hypothesis that GABA uptake is more efficient in the ICCN of GEPR-9s Quotation withheld because this record is not cleared for redistribution. contradicts → the disinhibition account carried over from hippocampal dentate gyrus findings (Farias et al. 1992; Buckmaster and Schwartzkroin 1994) Quotation withheld because this record is not cleared for redistribution. builds-on → Faye-Lund and Osen's (1985) description of the rat inferior colliculus Quotation withheld because this record is not cleared for redistribution. GEPR-3 —is-a→ animal model GEPR-3 animal model differs in: what fixes the category: an assigned score of 3 on the 0-9 seizure scale · strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. correlation correlation Quotation withheld because this record is not cleared for redistribution. correlation correlation WHOSE RESULT THIS IS: ns in the ICCN and the audiogenic response score (Ribak et al. 1988b). - THE RESULT OR THE NUMBER IS THE CITED WORK'S. Read, not swept - the trailing-citation shape is about 55% precise and the main clause is what decides it. Second reading pass over the 25 candidates left after 2026-08-25 11:39: 9 marked, 16 refused. the same sentence, tagged twice. Quotation withheld because this record is not cleared for redistribution. significance test significance test Quotation withheld because this record is not cleared for redistribution. mean mean Quotation withheld because this record is not cleared for redistribution. cell counting (stereological-style counts per section) cell counting (stereological-style counts per section) Quotation withheld because this record is not cleared for redistribution. Epilepsy-prone GEPR-9 rats have far more GAD-positive neurons in the inferior colliculus than Sprague-Dawley rats. Quotation withheld because this record is not cleared for redistribution. Two independent anatomical methods, immunocytochemistry and in situ hybridisation, were used to count GABAergic neurons. Quotation withheld because this record is not cleared for redistribution. Nissl analysis indicated the increase was not due to non-GABAergic neurons switching to a GABAergic phenotype. Quotation withheld because this record is not cleared for redistribution. Across GEPR-9s, Sprague-Dawley rats and their crossed offspring, the number of small neurons in the ICCN rises together with the audiogenic response score. WHOSE RESULT THIS IS: ns in the ICCN and the audiogenic response score (Ribak et al. 1988b). - THE RESULT OR THE NUMBER IS THE CITED WORK'S. Read, not swept - the trailing-citation shape is about 55% precise and the main clause is what decides it. Second reading pass over the 25 candidates left after 2026-08-25 11:39: 9 marked, 16 refused. 'a significant positive…' - a self-citation to earlier work, which is still not THIS paper's result. Quotation withheld because this record is not cleared for redistribution. Moderately seizing GEPR-3 rats have significantly more small ICCN neurons than Sprague-Dawley rats, and the count matches the value the correlation line predicted in advance. Quotation withheld because this record is not cleared for redistribution. Knife cuts placed between the central and external nuclei of the IC block audiogenic seizures, as do lesions of the ICCN itself or of the lateral lemniscus. Quotation withheld because this record is not cleared for redistribution. The ICCN-to-external-nucleus projection is the route by which seizure activity leaves its site of initiation in the ICCN and propagates. Quotation withheld because this record is not cleared for redistribution. The number of axosomatic synapses per soma in the ICCN is the same in GEPR-9s and Sprague-Dawley rats, which rules out the idea that the extra GABAergic neurons act by adding inhibitory contacts onto cell bodies. Quotation withheld because this record is not cleared for redistribution. Audiogenic-seizure susceptibility in GEPRs was indicated to be an autosomal dominant trait. Quotation withheld because this record is not cleared for redistribution. Electron microscopy indicates that four of the six major cell types of the central nucleus of the inferior colliculus are GABAergic inhibitory neurons. Quotation withheld because this record is not cleared for redistribution. inferior colliculus (IC) inferior colliculus (IC) Quotation withheld because this record is not cleared for redistribution. three subdivisions of the IC three subdivisions of the IC Quotation withheld because this record is not cleared for redistribution. GEPR-3 GEPR-3 Quotation withheld because this record is not cleared for redistribution. genetically epilepsy-prone rats genetically epilepsy-prone rats Quotation withheld because this record is not cleared for redistribution. seizure score seizure score Quotation withheld because this record is not cleared for redistribution. lesion site lesion site Quotation withheld because this record is not cleared for redistribution. seizure severity seizure severity Quotation withheld because this record is not cleared for redistribution. total number of Nissl-stained cells total number of Nissl-stained cells Quotation withheld because this record is not cleared for redistribution. sizes of ICCN neurons sizes of ICCN neurons Quotation withheld because this record is not cleared for redistribution. 200% — increase in small GAD-positive cells in the IC of GEPR-9s relative to Sprague-Dawley rats (medium cells increased 90%) Quotation withheld because this record is not cleared for redistribution. 100% — increase in small Nissl-stained neurons in the ICCN of GEPRs, against a 30% increase for medium-sized neurons Quotation withheld because this record is not cleared for redistribution. 70% — excess of small ICCN neurons in GEPR-9s over SD rats in the 2-micrometre semi-thin section counts, with medium neurons up 30% Quotation withheld because this record is not cleared for redistribution. 25% ... 36% — proportion of small ICCN neurons that are GAD-positive in Sprague-Dawley rats versus GEPR-9s Quotation withheld because this record is not cleared for redistribution. 0.91 — coefficient of linear correlation between audiogenic response score and the number of small ICCN neurons Quotation withheld because this record is not cleared for redistribution. 29.50+2.17 — mean small-neuron count per unit area in the ICCN of GEPR-3 rats Quotation withheld because this record is not cleared for redistribution. 3:1 — minimum ratio of seizure-prone to seizure-resistant offspring in GEPR-9 x Sprague-Dawley crosses Quotation withheld because this record is not cleared for redistribution. 28 rats — number of animals contributing to the correlation between small-neuron number and audiogenic response score Quotation withheld because this record is not cleared for redistribution.

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