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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Electrophysiologic and behavioral changes in cats following section of the brachia of the inferior colliculi].

Evoked potentials to acoustic stimuli were recorded in the temporal cortical area, the medial geniculate body and the posterior lateral thalamic nucleus in acute experiments on anaesthetized cats. Section of the brachia of the inferior colliculi in an acute experiment resulted in the disappearance of potentials in the examined structures. A distinct correlation has been revealed between the recovery of evoked potentials in the cortico-thalamic auditory structures (in four to six weeks) and the possible elaboration of conditioned reactions within this time period after lesion of the inferior colliculi brachia. The involvement of the temporal area in the general brain activity appears to be one of the major conditions for the formation of new conditioned connections. Possible ways of restoration of afferent input to the temporal cortical area after lesion of the inferior colliculi brachia are discussed.

Animals↗
PubMedDate not supplied

[Behavior of cats after unilateral section of the brachii of the inferior colliculi].

In experiments on 13 cats a unilateral section of the brachii of inferior colliculi produced a stable interhemispheric asymmetry not only in the auditory system, but in other (vestibular, visual, somatic, olfactory) analysers as well, which led to a disturbance of adequate space perception. This was manifested in orienting reactions directed only to the side of brain lesion. Animals were no more able to distinguish between the right and left troughs either by spatial or by modal cues. A complete "disregard" by the animals of the trough contralateral to the side of lesion suggests a hemispheric lateralization of conditioned connections providing for an adequate direction of the animals' running.

Animals↗
PubMedDate not supplied

[The role of the temporal areas in conditioned reflex activity following section of the brachia of the inferior colliculi].

The role of the neocortex temporal areas in the closing function was studied in chronic experiments on cats in the norm and after section of the posterior colliculi brachia. The techniques of functional elimination of the temporal neocortex by cold and section of the posterior colliculi brachia were used. Functional elimination of the cortical temporal areas prevents formation of a stable conditioned reflex in the first twenty sessions with cooling. Conditioned reflexes elaborated after section of the posterior colliculi brachia are not manifested in the case of cooling of the temporal areas throughout the period of observation (18 sessions). At the same time the conditioned reflexes elaborated before the section, are restored quite rapidly (five to six sessions). Hence, the neocortex temporal areas are more important for setting up conditioned connections than for their preservation and the use of connections previously elaborated.

Animals↗
PubMed1992

Organization of the superior olivary complex in the guinea pig: II. Patterns of projection from the periolivary nuclei to the inferior colliculus.

The superior olivary complex is a major source of auditory projections to the inferior colliculus. Although the projections from the medial and lateral superior olivary nuclei have been well characterized, projections from the surrounding periolivary nuclei have received relatively little attention. In the guinea pig, cytoarchitectonic criteria can be used to distinguish 11 periolivary nuclei that can be divided into four groups. These are: 1) a lateral group that comprises the anterolateral and posteroventral periolivary nuclei and the lateral nucleus of the trapezoid body; 2) a dorsal group that comprises the dorsal and dorsolateral periolivary nuclei; 3) a ventral group that comprises the rostral, ventromedial, and anteroventral periolivary nuclei and the ventral nucleus of the trapezoid body; and 4) a medial group that comprises the superior paraolivary nucleus and the medial nucleus of the trapezoid body. In the present study we used horseradish peroxidase and fluorescent tracers to identify olivocollicular cells in each of the periolivary nuclei. The lateral, dorsal, and medial periolivary groups project bilaterally, and the ventral periolivary group projects ipsilaterally. Within groups, individual nuclei contain different numbers of olivocollicular cells. The posteroventral periolivary nucleus is the only periolivary nucleus that does not project to the inferior colliculus. The superior paraolivary nucleus is the only periolivary nucleus that contains significant numbers of individual cells that project to both inferior colliculi. The remaining periolivary nuclei project only ipsilaterally or contain separate populations of cells that project to the two inferior colliculi.

Animals↗
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↗
PubMed1975

Midbrain deafness following head injury.

A patient is described who became deaf following a head injury. Postmortem examination revealed bilateral lesions of the lateral lemnisci and inferior colliculi. The clinical pattern of midbrain deafness is examined and compared with syndromes of cortical and peripheral auditory impairment.

Audiometry↗
PubMed1992

Case report: neuropathology of methyl bromide intoxication.

The neuropathological findings in a man and his dog both of whom died after acute exposure to methyl bromide are presented. The dog had cerebral oedema, most marked in the depths of cortical sulci. The man survived 30 days after the initial illness and his brain contained well-defined symmetrical lesions in the mammillary bodies and inferior colliculi. He also had a peripheral neuropathy and lymphocytic thyroiditis. The pathology in the central nervous system has features resembling Wernicke's encephalopathology; the mechanism by which methyl bromide may produce such lesions is discussed.

Adult↗
PubMed1975

Averaged evoked potentials in cats with lesions of auditory pathway.

Averaged evoked activity was recorded from needle electrodes placed at the vertex of the calvaria and adjacent to each bulla in anesthetized cats in response to click stimuli. The portion of the response from 0 to 10 msec was analyzed. Activity during the first 3 msec was greatly reduced on the side ipsilateral to a lesion involving destruction of the cochlea or section of the eighth nerve and its blood vessels. Activity after 4 msec was greatly reduced on the side ipsilateral to destruction of the cochlear nuclei. No effect was found with destruction of both inferior colliculi. The bulla-vertex evoked responses were also compared to those recorded from the round window. The results support the premise that change in the wave-form of the early evoked potential can be used to determine site of loss of acoustic information along the auditory pathway.

Acoustic Stimulation↗
PubMed1992

Effects of neural transplantation on seizures in the immature genetically epilepsy-prone rat.

To study the hypothesis that neural transplantations can alter seizure susceptibility in a genetic animal model of epilepsy, 93 pubescent genetically epilepsy-prone rats with stage 9 seizures received either bilateral inferior colliculi (N = 21) or lateral ventricle (N = 42) transplants or sham transplants (N = 30). The grafts consisted of embryonic locus ceruleus, neocortical, or cerebellar tissue. Starting 2 days after the transplantation the rats were subjected to audiogenic stimulations every other day for 61 days. Latency to the running and tonic phase, seizure severity score, and duration of the tonic and clonic phase were compared in the neural transplant and sham-operated controls. Rats that received transplants had a longer latency to the tonic phase and a shorter duration of the clonic phase than the controls. At age 110 days the rats had electrodes implanted bilaterally into the angular bundle and were kindled. No difference in kindling rate was found between the rats that received neural grafts and the sham-operated controls. Cerebrospinal fluid concentration of norepinephrine was not altered by the transplants. This study demonstrates that the anticonvulsant effects of neural transplants, using the genetically epilepsy-prone model of epilepsy, are mild.

Acoustic Stimulation↗
PubMed1978

Changes in latency and duration of neural responding following developmental auditory deprivation.

The initial latency of spikes evoked by click stimulation and the duration over which spiking occurred were observed in the inferior colliculi of rats. One ear of these animals had been deprived of early auditory stimulation by ligation of the external meatus. Clicks presented to the normally experienced ears evoked spikes in the opposite colliculus with latencies that depended on the characteristic frequency of the unit. Low-frequency (less than 5 kHz) units had latencies from 6-10 msec. Latencies declined to 3-4 msec for high frequency (greater than 20 kHz) units. After an ear had been deprived of sound from 10 days after birth, response latencies of units in the opposite colliculus with characteristic frequencies below about 10 kHz were comparable to controls, but most units above 10 kHz had latencies 2-3 times control latencies. Spike activity evoked in these units did not continue as long as that for most comparable control units. Ears sound deprived for an equal period from 60 days after birth also had changes in latencies and response durations, but these were much less than in the developmentally deprived. Latencies of gross potentials at the auditory nerve were not affected by early deprivation, indicating a central origin for the latency changes.

Acoustic Stimulation↗
PubMed1975

Serotonin-sensitive adenylate cyclase activity of immature rat brain.

Cell-free preparations from superior and inferior colliculi of very young rats (1-3 days old) contained adenylate cyclase systems which were highly responsive to serotonin. The response to serotonin declined markedly during early development and was very low at maturity. Adenylate cyclase activity in the 10,000 times g particulate fraction from colliculi of newborn rats was significantly stimulated by 0.05 muM serotonin. Half-maximal activation was produced with less than 1 muM serotonin. Maximal stimulation of collicular adenylate cyclase was about 80% above basal enzyme activity and occurred with approximately 50 muM serotonin. Tryptamine and several derivatives of serotonin produced responses which were comparable to that obtained with serotonin; 5-methoxytryptamine was uniformly the most active compound tested. Norepinephrine or dopamine produced much smaller increases in adenylate cyclase activity. Stimulation of collicular adenylate cyclase by serotonin was significantly but incompletely blocked by serotonin antagonists, including d-lysergic acid diethylamide (d-LSD), 2-bromo-d-lysergic acid diethylamide, methysergide, 1-methyl-8 beta-carbobenzyloxy-aminomethyl-10 alpha-ergoline and cyproheptadine. Chlorpromazine also produced partial blockade. In contrast, l-lysergic acid diethylamide, haloperidol, propranolol, phenoxybenzamine and morphine were ineffective as serotonin blocking agents. Of the compounds which produced a partial blockage of serotonin action, d-LSD, cyproheptadine and chlorpromazine were themselves capable of stimulating adenylate cyclase activity. These results are consisent with the existence of multiple receptors in rat brain which are capable of interacting with indoleamines.

5-Hydroxytryptophan↗
PubMedDate not supplied

Superposition of binaural influences on single neuron activity in the medial superior olive elicited by electrical stimulation of the osseous spiral laminae.

The single unit response of medial superior olive (accessory nucleus) neurons was investigated, when elicited by electrical stimulation of nervous processes in the osseous spiral laminae in both cochleae and also by antidromic stimulation from the inferior colliculi. The osseous spiral laminae were stimulated at the first, second or third turns with grounding of one of the unstimulated turns. Time of signal arrival differences (delta tau) at the two cochleae and also intensity differences (deltai) were varied. (2) It is concluded that (A) binaural interaction in the MSO is not based on totally excitatory or inhibitory influences from either ear, but on cycles of excitation and inhibition; (B) these influences approximately obey the laws of superposition, i.e., the influences add linearly to determine discharge. (3) It is demonstrated that: (a) electrical stimulation, unlike acoustical stimulation, elicits a regular neural response; (b) the neural response functions elicited by changes in delta tau are deltai exhibit maxima and minima and are not smooth functions; (c) fine latency changes in the neural response are correlated with changes in delta tau and deltai; (d) the stimulation of different turns of the osseous spiral laminae (producing different current flows) elicits a different neural response depending on the turn stimulated, an effect reflecting the anatomical tonotopic arrangement of the medial superior olive; (e) changes in the stimulus differences delta tau and deltai are correlated with the ratio of the spike count in a short period following the stimulus, to the spike count in a longer total period; (f) changes in the stimulus differences delta tau and deltai elicit a neural response which varies according to the turn stimulated.

Animals↗
PubMed1976

[Linear dimensions of the lamina of the tectum mesencephali during human ontogenesis].

The dynamics of the establishment of linear dimensions of the lamina of tectum mesencephali in ontogenesis was studied in 145 preparations of human brain. The investigation was performed with by the M. M. Sauliak-Savitskaja apparatus (1953). The obtained data were processed by the method of mathematical analysis. The relief of the superior colliculi was found to be formed earlier than that of the inferior colliculi. The linear dimensions of both colliculi are practically equal to those of adult men during the third year of life. No correlative relationship between the sex of the objects under study and the linear dimensions of the lamina of tectum mesencephali was found as well as between thr right and left parts of the lamina tecti. The linear dimensions of it in all age groups are very variable.

Adolescent↗
PubMed1979

Bulbospinal projections to the intermediolateral cell column: a neuroanatomical study.

The location of those neurones in the brain stem that project to the intermediolateral column (ILC) from which preganglionic sympathetic neurones have their origin was studied by the method of retrograde transport of horseradish peroxidase (HRP). In cats 30--50 nl of a 30% HRP solution was injected into the region of the ILC at T3 or L1 on one side. After a survival period of 72 h the lower brain stem from C1 to the inferior colliculi was sectioned and prepared for histological study under brightfield illumination. Neurones stained with exogenous HRP were found in three regions: (a) in the ipsilateral, dorsomedial part of the nucleus of the solitary tract (NTS) (43% of all labeled neurones), in the cranial part of the NTS, and also on the contralateral side (7%); (b) in the ventrolateral reticular formation beginning at the level of the obex up to 8 mm cranial to the obex (25% ipsilateral, 3% contralateral); and (c) in the ventral part of the raphe nuclei (postpyramidal and inferior central nucleus) from 2 to 9 mm cranial to the obex (22%).

Animals↗
PubMed1978

Encephalomyelopathy following intrathecal methotrexate treatment in a child with acute leukemia.

A previously undescribed type of encephalomyelopathy after prophylactic intrathecal methotrexate (MTX) treatment for acute leukemia is reported. The patient was treated systemically with vincristine, MTX, stereoids and mercaptopurine. Radiation therapy was not given. The neurologic symptoms started 24 hours after the completion of the fifth intrathecal MTX instillation and death ensued 18 days later. The lesions consisted of superficial and sharply circumscribed areas of incomplete necrosis with astrocytosis on the base of the brain and along the insula regions, around the foramina of Luschka, and over the superior and inferior colliculi. Similar superficial lesions were found over the surface of the cerebellum and along most of the surface of the spinal cord. Most of the affected areas in the brain were located under the large subarachnoid cisterns. In the cord the lesions were most pronounced along the entrance zones of the roots. There was also a severe loss of anterior horn cells. There were no signs of meningeal leukemia, no pathological changes were caused by the intrathecal MTX treatment.

Acute Disease↗