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PubMed2002

Midbrain deafness with normal brainstem auditory evoked potentials.

The authors report two cases of patients with word deafness. The word deafness occurred after a head injury for the first patient and after an arterio venous malformation embolization for the second patient. MRI demonstrated bilateral lesions of the inferior colliculi but brainstem auditory-evoked potentials (BAEP) were within normal limits. These cases demonstrated that lesions involving the two inferior colliculi induced pure word deafness but do not affect BAEP.

Balloon Occlusion↗
PubMed1985

Ocular signs in thiamine-deficient monkeys and in Wernicke's disease in humans.

Thiamine deficiency in the monkey is the animal counterpart of Wernicke's disease in humans. In the present study, thiamine deficiency was induced in 11 monkeys while three monkeys were given paired feedings supplemented by thiamine hydrochloride and three monkeys were maintained on regular chow. The typical clinical symptoms were apathy, inattention to peripheral stimuli, ataxia, ptosis, mydriasis progressing to pupillary areflexia, nystagmus, and ophthalmoparesis progressing to total ophthalmoplegia. With thiamine treatment, recovery was prompt and complete in mild to moderate cases but delayed and incomplete in severe cases. The animals were killed six or more months after discontinuance of the experiments to determine the chronic effects of treated thiamine deficiency. The significant abnormalities in the brain stem were symmetric gliosis and neuronal loss in the inferior colliculi, the regions of the third and sixth nerve nuclei, and the medial vestibular nuclei. White matter was characteristically spared. With the exception of the inferior colliculi, the target sites for neuropathologic changes were the centers for ocular motor control.

Animals↗
PubMed1989

The uptake of [14C]deoxyglucose into brain of young rats with inherited hydrocephalus.

The effect of hydrocephalus on cerebral glucose utilization as reflected by deoxyglucose uptake has been examined in rats with inherited hydrocephalus at 10, 20, and 28 days after birth using a semiquantitative method. Injection of [14C]deoxyglucose intraperitoneally was followed by freezing the brain, sectioning, and quantitative autoradiography of 10 brain regions. Brain [14C] concentration, cortical thickness, and plasma glucose concentrations were measured. Maximal thinning of the cerebral cortex had already occurred by 10 days after birth, although obvious symptoms such as gait disturbance developed after 20 days. In control rats, the cerebral isotope concentration was lower and more homogeneous at 10 days than at 20 or 28 days, which may be a reflection of the use of metabolic substrates other than glucose in younger animals. In order to make comparisons between control and hydrocephalic groups, tissue isotope concentrations were normalized to cerebellar cortex which was not affected by the hydrocephalus at any age. In hydrocephalic rats at 10 and 20 days, the concentration of [14C] was lower in all areas except the inferior colliculi and pons but the reduction was only significant in the sensory-motor cortex at 10 days and in the caudate nuclei at 20 days. By 28 days after birth, all areas except the cerebellum (six cortical regions, inferior colliculi, pons, and caudate) had significantly lower isotope concentrations in the hydrocephalic group. It is concluded that cerebral glucose metabolism is significantly reduced by 28 days after birth in H-Tx rats with congenital hydrocephalus and that less marked reductions occur prior to 28 days.

Aging↗
PubMed1993

Distribution of parvalbumin immunoreactivity in the cat brain stem.

We studied the distribution of parvalbumin-immunoreactive cell bodies and fibers in the cat brain stem. A high or moderate density of perikarya containing parvalbumin was observed in the periaqueductal gray, interpeduncular nucleus, nucleus of the trapezoid body, superior and inferior colliculi, and in the substantia nigra. The nucleus ruber, cuneiform nucleus, preolivary nucleus, retrorubral nucleus, paracentral division of the tegmental reticular nucleus, central and lateral tegmental fields, and the pericentral division of the dorsal tegmental nucleus had the lowest density of immunoreactive cell bodies. Moreover, a high or moderate density of parvalbumin immunoreactive processes was visualized in the nucleus ruber, substantia nigra, superior and inferior colliculi, periaqueductal gray, nucleus sagulum, cuneiform nucleus, Kölliker-Fuse nucleus, nucleus of the trapezoid body, vestibular nuclei, dorsal motor nucleus of the vagus, and in the lateral reticular nucleus. Finally, a few immunoreactive fibers were observed in the pontine gray, nucleus coeruleus, marginal nucleus of the brachium conjunctivum, nucleus of the solitary tract, inferior olive, and in the tegmental fields.

Animals↗
PubMed1997

Immunoblot analyses on the differential distribution of NR2A and NR2B subunits in the adult rat brain.

Quantitative immunoblot analyses were carried out to study the distribution of N-methyl-D-aspartate (NMDA) receptor subunit 2A and 2B (NR2A and NR2B, respectively) at the protein level in the adult rat brain. Highest levels of NR2A were detected in cerebral cortex and hippocampus, followed at more or less similar levels (about 36-72% of cerebral cortex) by striatum, thalamus, olfactory bulb, superior and inferior colliculi, and cerebellum. The lowest levels were detected in midbrain and lower brain stem (30-31% of cerebral cortex). The NR2B was more dramatic in differential distribution than the NR2A. Highest levels of NR2B were found in telencephalic (olfactory bulb, cerebral cortex, hippocampus, and striatum) and thalamic regions, and expression in superior and inferior colliculi, midbrain, lower brain stem, and cerebellum were significantly lower (4-25% of cerebral cortex). Interestingly, NR2B proteins were barely detectable in the cerebellum. When the postsynaptic density (PSD) fractions were compared, the amount of NR2B in the cerebellar PSD fraction was only 1.8% of that present in the cerebral PSD fraction where the subunit is highly enriched. Immunoblot analyses with a phosphotyrosine-specific antibody showed that the molecular sizes of major phosphotyrosine-containing proteins in forebrain and hindbrain are 180 and 45 kDa, respectively. The regional distribution of the 180 kDa major phosphotyrosine protein was very similar to that of NR2B, and the protein could be immunoprecipitated by NR2B antibody. Our data shows that NR2A and NR2B subunits are differentially distributed in the brain in an overlapping manner, and that the major phosphotyrosine-containing protein of 180 kDa in forebrain is the NR2B.

Animals↗
PubMedDate not supplied

Discrete mapping of brain Mu and delta opioid receptors using selective peptides: quantitative autoradiography, species differences and comparison with kappa receptors.

The opioid peptides, [3H]DAGO and [3H]DPDPE, bound to rat and guinea pig brain homogenates with a high, nanomolar affinity and to a high density of mu and delta receptors, respectively. [3H]DAGO binding to mu receptors was competitively inhibited by unlabelled opioids with the following rank order of potency: DAGO greater than morphine greater than DADLE greater than naloxone greater than etorphine much greater than U50488 much greater than DPDPE. In contrast, [3H]DPDPE binding to delta receptors was inhibited by compounds with the following rank order of potency: DPDPE greater than DADLE greater than etorphine greater than dynorphin(1-8) greater than naloxone much greater than U50488 much greater than DAGO. These profiles were consistent with specific labelling of the mu and delta opioid receptors, respectively. In vitro autoradiographic techniques coupled with computer-assisted image analyses revealed a discrete but differential anatomical localization of mu and delta receptors in the rat and guinea pig brain. In general, mu and delta receptor density in the rat exceeded that in the guinea pig brain and differed markedly from that of kappa receptors in these species. However, while mu receptors were distributed throughout the brain with "hotspots" in the fore-, mid- and hindbrain of the two rodents, the delta sites were relatively diffusely distributed, and were mainly concentrated in the forebrain with particularly high levels within the olfactory bulb (OB), n. accumbens and striatum. Notable regions of high density of mu receptors in the rat and guinea pig brain were the accessory olfactory bulb, striatal "patches" and "streaks," amygdaloid nuclei, ventral hippocampal subiculum and dentate gyrus, numerous thalamic nuclei, geniculate bodies, central grey, superior and inferior colliculi, solitary and pontine nuclei and s. nigra. Tissues of high delta receptor concentration included, OB (external plexiform layer), striatum, n. accumbens, amygdala and cortex (layers I-II and V-VI). Delta receptors in the guinea pig were, in general, similarly distributed to the rat, but in contrast to the latter, the hindbrain regions such as the thalamus, geniculate bodies, central grey and superior and inferior colliculi of the guinea pig were apparently more enriched than the rat. These patterns of mu and delta site distribution differed dramatically from that of the kappa opioid sites in these species studied with the peptide [125I]dynorphin(1-8).

Animals↗
PubMedDate not supplied

A preliminary single case magnetic resonance imaging investigation into maxillary frontal-parietal manipulation and its short-term effect upon the intercranial structures of an adult human brain.

OBJECTIVE: To investigate the hypothesis that external cranial manipulation can cause change within the structures of the human brain. DESIGN: Single subject. SETTING: Private office. PARTICIPANT: A 42-yr-old man. INTERVENTION: MRI scan was administered without manipulative pressure but with the investigator's contacts on the test subjects maxillary palate and frontal/parietal region surrounding the bregma. OUTCOMES: Measurements were taken along the superior border of the corpus callosum, the width of the fornix column, the exposed anterior/superior wall of the lateral ventricle posterior to the fornix, the angular surface of the cerebellar central lobule and the posterior surface of the inferior colliculi. RESULTS: Results from the second MRI (administered during the application of external cranial pressure) demonstrated elimination of a 5-mm peak along the superior border of the corpus callosum and a 4-mm reduction in the width of the fornix column. The exposed anterior/superior wall of the lateral ventricle posterior to the fornix column increased 51 degrees cephalad with manipulative application. The angular surface of the central lobule altered by minus 26 degrees, and the posterior surface of the inferior colliculi varied by minus 7 degrees. The subject experienced no change in his asymptomatic condition as a result of this study. CONCLUSION: The present study supports the theory that external cranial manipulation affects the structure of the brain. It also suggests support for the theory regarding suture mobility.

Adult↗
PubMed1999

Neurotoxicity of 1,3,5-trinitrobenzene (TNB): immunohistochemical study of cerebrovascular permeability.

1,3,5-Trinitrobenzene (TNB) is a soil and water contaminant at certain military installations. Encephalopathy in rats given 10 daily oral doses of TNB has been reported. The lesion was bilaterally symmetric vacuolation and microcavitation in the cerebellar roof nuclei, vestibular nuclei, olivary nuclei, and inferior colliculi. The contribution of the blood-brain barrier (BBB) in the genesis of these lesions remains uncertain. One of the main goals of the present work was to evaluate the functional state of the BBB. Male Fischer 344 rats (five rats/group) were euthanatized after four, five, six, seven, eight, or 10 daily doses of TNB (71 mg/kg). A different set of rats (five rats/group) was allowed to recover for 10 or 30 days after receiving 10 doses of TNB. Integrity of the BBB was assessed by immunohistochemical staining for extravasated plasma albumin on paraffin-embedded sections. Rats euthanatized after four to eight doses had no lesions, and albumin extravasation in the susceptible regions of the brain was minimal. Rats receiving 10 daily doses of TNB had bilaterally symmetric vacuolation and microcavitation in the cerebellar nuclei, vestibular nuclei, and inferior colliculi in association with multifocal, often confluent foci of extravasated albumin in susceptible nuclei. Albumin was present in vascular walls, extracellular space, and neurons. Immunoreactivity in neurons was of two types: cytoplasmic staining representing pinocytic uptake and homogeneous staining of the entire neuron (nucleus and cytoplasm) due to uncontrolled albumin leakage through the damaged cell membrane. In rats allowed to recover for 10 days, the microcavitated foci were infiltrated by glial and gitter cells. Albumin immunoreactivity was present as extracellular granular debris, and neuronal staining (for albumin) was mild. In rats allowed to recover for 30 days, immunoreactivity to albumin was not seen. This study demonstrates that TNB-mediated tissue damage is accompanied by breakdown of the BBB. The presence of vacuolation and associated extravasated serum proteins in TNB-treated rats is an indication of vasogenic brain edema, which appears to be a critical event in TNB toxicity. Additional studies are needed to determine the reason for selective regional vulnerability and brain microvascular susceptibility to TNB.

Albumins↗
PubMed2006

Development and resolution of brain lesions caused by pyrithiamine- and dietary-induced thiamine deficiency and alcohol exposure in the alcohol-preferring rat: a longitudinal magnetic resonance imaging and spectroscopy study.

Wernicke's encephalopathy (WE) is characterized by lesions in thalamus, hypothalamus (including mammillary nuclei), and inferior colliculi, results in serious disabilities, has an etiology of thiamine deficiency, is treatable with thiamine, and occurs most commonly with alcoholism. Despite decades of study, whether alcohol exposure exacerbates the neuropathology or retards its resolution remains controversial. To examine patterns of brain damage and recovery resulting from thiamine deprivation with and without alcohol exposure, we conducted in vivo magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) at 3 T in alcohol-preferring (P) rats, which had voluntarily consumed large amounts of alcohol before thiamine manipulation. A total of 18 adult male P rats (nine alcohol-exposed) received a thiamine-deficient diet for 2 weeks: 10 (five alcohol-exposed) received intraperitoneal (i.p.) pyrithiamine (PT) and eight (four alcohol-exposed) received i.p. thiamine supplementation. Neurological signs developed by day 14. Rats were scanned before thiamine depletion and 18 and 35 days after thiamine repletion. Two-dimensional J-resolved MRS single-voxel spectra with water reference were collected in a voxel subtending the thalamus; metabolite quantification was corrected for voxel tissue content. MRI identified significant enlargement of dorsal ventricles and increase in signal intensities in thalamus, inferior colliculi, and mammillary nuclei of PT compared with thiamine-treated (TT) groups from MRI 1-2, followed by significant normalization from MRI 2-3 in thalamus and colliculi, but not mammillary nuclei and lateral ventricles. Voxel-by-voxel analysis revealed additional hyperintense signal clusters in the dorsal and ventral hippocampus and enlargement of the fourth ventricle. MRS showed a significant decline and then partial recovery in thalamic N-acetylaspartate, a marker of neuronal integrity, in PT compared with TT rats, with no change detected in creatine, choline, or glutamate. PT rats with prior alcohol exposure exhibited attenuated recovery in the thalamus and arrested growth of the corpus callosum; further, two of the five alcohol-exposed PT rats died prematurely. Parenchymal and ventricular changes with thiamine manipulation concur with human radiological signs of WE. The enduring macrostructural and neurochemical abnormalities involving critical nodes of Papez circuit carry liabilities for development of amnesia and incomplete recovery from other cognitive and motor functions subserved by the affected neural systems.

Alcohol-Induced Disorders, Nervous System↗
PubMed1985

Observations on the axonal and neuronal typology in the commissure of the inferior colliculus of the rabbit.

Different types of neurons and fibres in the Commissura colliculi inferiores (CCI) of the rabbit are described using the Golgi rapid method. Neurons were classified according to soma shape, dendritic arborization and location within the commissure. Four main neuronal types were found i.e., (1) Vertical cells; (2) Multipolar cells; (3) Horizontal cells; (4) Small rounded cells. With exception of the latter, all neuron types could be divided into several cells varieties. Four different types of fibres were observed within the CCI: a) myelinated commissural fibres; b) fibres from the dorsal cortex of the colliculus; c) fibres from the dorsal PAG nucleus; d) intrinsic fibres from the neurons of the CCI. The results of this study demonstrate the non-homogeneous structure of the CCI, which was earlier shown in the cat and rat. Also, a division of some of the commissural neurons into local and projecting neurons, based on their axonal branching pattern is suggested.

Animals↗
PubMed1995

Pre- and postnatal effects of chronic maternal hypoxia on substance-P immunoreactivity in rabbit brainstem regions.

The effect of chronic maternal hypoxia on substance-P immunoreactivity (SPI) was examined in brainstem regions of fetal (gestational day E-28), neonatal (postnatal days 3, 7, 14, 21), and adult rabbits. Time-dated pregnant rabbit does were housed in environmental chambers at gestational day E-10. Between E-14 and E-28, the pregnant does were separated into two groups. Group 1, the control group, breathed 21% O2/79% N2 and group 2 the hypoxia-exposed group, breathed 12-14% O2/86-88% N2. Sacrifice occurred at various days depending on the experimental paradigm. On gestational day E-28, 6 pregnant animals were delivered by hysterotomy and the pups were immediately sacrificed. On and after gestational day E-28, the remaining 12 pregnant animals breathed room air. These animals delivered spontaneously between E-30 and E-32 and the pups remained with their mothers until sacrifice. On postnatal days 3, 7, 14, and 21, SPI was measured by radioimmunoassay in the colliculi (fetal animals), superior and inferior colliculi (postnatal analysis), pons and medulla (both groups). In both prenatally normoxia- and hypoxia-exposed animals, SPI was highest in the medulla, intermediate in the pons and lowest in the colliculi. SPI increased with development. Chronic maternal hypoxia did not alter the caudal-rostral profile nor did it alter the maturational increase in SPI. However, chronic maternal hypoxia increased SPI in prenatal animals and decreased SPI in postnatal animals at 14 and 21 days of life but not in postnatal 3- and 7-day-old animals. These data support the concept that regional differences exist in basal SPI within the brainstem of fetal and neonatal animals, and that maternal hypoxia has both immediate and long-term effects on brainstem SPI.

Animals↗
PubMed1988

Chronic maternal hypoxia. Effect of mid-gestational maternal hypoxia on methionine-enkephalin concentrations within pre- and postnatal rabbit brainstem regions.

We examined the effect of chronic maternal hypoxia on methionine-enkephalin concentrations in fetal (gestational day E-28) and neonatal (postnatal days 3, 7, 21) brainstem regions. Pregnant rabbits were housed in environmental chambers at gestational day E-10. Between E-14 and E-28 the pregnant rabbits were separated into two groups. Group I were controls (C) and breathed 21% O2/79% N2 and group II, hypoxia (H), breathed 12-14% O2/86-88% N2. Sacrifice occurred at various days depending on the experimental paridigm. On gestational day E-28, the first group of 6 pregnant animals (3 C, 3 H) were delivered by hysterotomy and the pups were immediately sacrificed. On and after gestational day E-28, the remaining 12 pregnant animals breathed room air. These animals delivered spontaneously between 30 and 32 days of gestation. The pups remained with their mothers until sacrifice. On postnatal days 3, 7, or 21, methionine-enkephalin was measured by radioimmunoassay in the colliculi (fetal animals), superior and inferior colliculi (postnatal animals), pons and medulla (both groups). In both normoxia-exposed and hypoxia-exposed animals, methionine-enkephalin was highest in the medulla, intermediate in the pons, and lowest in the colliculi. Chronic maternal hypoxia significantly increased the methionine-enkephalin concentration in the pons of E-28 fetuses (p less than 0.02). Levels were increased in the medulla as well but these did not reach significance (p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed2002

Serotonin in the inferior colliculus.

It has been recognized for some time that serotonin fibers originating in raphe nuclei are present in the inferior colliculi of all mammalian species studied. More recently, serotonin has been found to modulate the responses of single inferior colliculus neurons to many types of auditory stimuli, ranging from simple tone bursts to complex species-specific vocalizations. The effects of serotonin are often quite strong, and for some neurons are also highly specific. A dramatic illustration of this is that serotonin can change the selectivity of some neurons for sounds, including species-specific vocalizations. These results are discussed in light of several theories on the function of serotonin in the IC, and of outstanding issues that remain to be addressed.

Acoustic Stimulation↗
PubMed2004

Auditory agnosia caused by a tectal germinoma.

The authors describe a patient with auditory agnosia caused by a tectal germinoma. Despite having normal audiometric tests, the patient failed to recognize words and musical characters. On head MRI, the inferior colliculi were infiltrated by tumor. Neuropsychological tests revealed severe impairment in recognition of environmental sounds and words, defective musical perception, and stop consonant-vowel discrimination. Inferior colliculus may play a role in the analysis of sound properties.

Acoustic Stimulation↗
PubMed1989

[35S]TBPS binding sites are decreased in the colliculi of mice with a genetic predisposition to bicuculline-induced seizures.

Several differences have been found in GABAergic function between the long sleep (LS) and short sleep (SS) mice which were genetically selected for different ethanol-induced sleeptimes, and it has been suggested that these differences may explain their differential ethanol sensitivity. However, these lines also differ in seizure susceptibility, a behavior which may also be mediated by GABAergic pathways. Thus, it is difficult to associate differences in GABA neurochemistry with either of these behaviors, particularly when only two selected lines are used. We measured differences in the density and affinity of the [35S]TBPS binding site on the GABAA receptor/Cl- ionophore complex in discrete brain areas; and in order to determine the relationship between receptor binding and behavioral differences, we included mice from 5 of the LS and SS recombinant inbred strains (LS x SS RI) in addition to mice from the LS and SS lines. [35S]TBPS binding in sagittal brain sections was analyzed by quantitative autoradiography, and the amount of binding differed depending on whether bicuculline was added to inhibit endogenous GABA binding. In the presence of bicuculline, the number of [35S]TBPS sites in SS mice was highest in the colliculi (4.5 +/- 0.5 pmol/mg protein), cerebellum (4.8 +/- 0.6 pmol/mg), hippocampus (3.2 +/- 0.7 pmol/mg) and cortex (2.9 +/- 0.3 pmol/mg). The Bmax was two-fold lower in both superior and inferior colliculi (IC) of LS mice. There were no differences between lines in Bmax in any other area and in Kd values in any area (58 +/- 4.0 nM).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Binaural interaction of a beating frequency-following response.

Frequency-following responses to 500-Hz tone bursts presented to the left ear and 540-Hz tone bursts presented to the right ear were recorded from human subjects. Recordings were made both under monaural and binaural conditions. The responses summed over monaural conditions (for left and right ear stimulation) were larger than the responses obtained in the binaural condition. This binaural interaction shows that the frequency-following response reflects binaural processing probably occurring at or below the level of the inferior colliculi.

Acoustic Stimulation↗
PubMed1978

The pontocerebellar projection of the uvula in the cat.

The occurrence of retrogradely labeled cells in the pontine nuclei was mapped following injections of 0.3-0.4 microliter of a horseradish peroxidase suspension (50% weight/volume) into the uvula (lob. IX of Larsell) in the cat. The uvula was found to receive afferents from three pontine cell collections. One of these is situated in the paramedian pontine nucleus close to the midline. It forms a fairly distinctly outlined longitudinal column of cells and is present at all levels of the pons except most rostrally and caudally. Another group, in the dorsolateral and lateral pontine nuclei, extends as a somewhat shorter cell column in the longitudinal direction. The third region consists of cells within the rostral part of the peduncular nucleus in its dorsomedial region. The pontine projection to the uvula is bilateral, with some preponderance of crossed connections. The projection to the uvula is organized according to the pattern determined previously for pontine projections to other parts of the cerebellum. A single lobule or part of its receives afferents from more than one cell group in the pons. The projecting cells are most often arranged in longitudinal columns. Correlations with data on the termination of afferents to the pons permit some conclusions regarding the sources of information reaching the uvula via the pons. Main sources seem to be the superior and inferior colliculi, the intracerebellar nuclei and the sensorimotor cortices.

Afferent Pathways↗