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The Ob and Yenisei Rivers contribute 37% of riverine freshwater inputs to the Arctic Basin and thus represent an important pathway for the land-Arctic ocean exchange of contaminants. Sampling was carried out in the Yenisei (2003) and Ob (2005) River estuaries and Kara Sea to address the general lack of reliable dissolved contaminant flux data for these major rivers. Contaminant analyses were performed by high resolution mass spectrometry on sample extracts taken from filtered large volume water samples (50-100 L) and concentrated in situ onto XAD-2 resin columns. Hexachlorocyclohexanes (HCHs), the polychlorinated biphenyl (PCB) mixtures Sovol and trichlorodiphenyl, dichlorodiphenyltrichloroethane (DDT), as well as "penta" brominated technical mixtures of polybrominated diphenyl ethers (PBDEs) are important contributors to persistent organohalogen contamination for these waterways. Dissolved fluxes to the Kara Sea were estimated at sigmaHCH 246 kg/yr, sigmaPCB 63 kg/yr, sigmaDDT 16 kg/yr, hexachlorobenzene 8 kg/yr, alpha-endosulfan 8 kg/ yr, dieldrin 5 kg/yr, sigmaPBDE 4 kg/yr, and chlordanes 4 kg/yr. Contaminant fluxes from these rivers are similar to those reported for major Canadian rivers, confirming expectations that the Ob and Yenisei are also major point sources for the Arctic basin.

Passive rotation of the trunk with respect to the head evoked cervico-ocular reflex (COR) eye movements in squirrel monkeys. The amplitude of the reflex varied both within and between animals, but the eye movements were always in the same direction as trunk rotation. In the dark, the COR typically had a gain of 0.3-0.4. When animals fixated earth-stationary targets during low-frequency passive neck rotation or actively tracked moving visual targets with head movements, the COR was suppressed. The COR and vestibulo-ocular reflex (VOR) summed during passive head-on-trunk rotation producing compensatory eye movements whose gain was greater than 1.0. The firing behavior of VOR-related vestibular neurons and cerebellar flocculus Purkinje cells was studied during the COR. Passive neck rotation produced changes in firing rate related to neck position and/or neck velocity in both position-vestibular-pause neurons and eye-head-vestibular neurons, although the latter neurons were much more sensitive to the COR than the former. The neck rotation signals were reduced or reversed in direction when the COR was suppressed. Flocculus Purkinje cells were relatively insensitive to COR eye movements. However, when the COR was suppressed, their firing rate was modulated by neck rotation. These neck rotation signals summed with ocular pursuit signals when the head was used to pursue targets. We suggest that the neural substrate that produces the COR includes central VOR pathways, and that the flocculus plays an important role in suppressing the reflex when it would cause relative movement of a visual target on the retina.

The vestibular nerve sends signals to the brain that code the movement and position of the head in space. These signals are used for a variety of functions, including the control of reflex and voluntary movements and the construction of a sense of self-motion. In order to carry out these functions, sensory vestibular signals need to be transformed in a variety of ways. Transformations are thought to occur at an early stage of sensory processing in the brain, and in many cases are apparent in the responses of neurons in the vestibular nuclei that receive direct inputs from the vestibular nerve. Several specific examples of sensory transformation in the vestibular nuclei are presented, and current hypotheses about the mechanisms that are used to produce the transformations are discussed.

The contribution of neck proprioceptive signals to signal processing in the vestibular nucleus was studied by recording responses of secondary horizontal canal-related neurons to neck rotation in the squirrel monkey. Responses evoked by passive neck rotation while the head was held stationary in space were compared with responses evoked by passive whole body rotation and by forced rotation of the head on the trunk. Most neurons (76%; 45/59) were sensitive to neck rotation. The nature and strength of neck proprioceptive inputs varied and usually combined linearly with vestibular inputs. In most cases (94%), the direction of the neck proprioceptive input was "antagonistic" or "reciprocal" with respect to vestibular sensitivity and, consequently, reduced the vestibular response during head-on-trunk rotation. Different types of vestibular neurons received different types of proprioceptive input. Neurons whose firing behavior was related to eye position (position-vestibular-pause neurons and position-vestibular neurons) were often sensitive to the position of the head with respect to the trunk. The sensitivity to head position was usually in the same direction as the neuron's eye position sensitivity. Non-eye-movement related neurons and eye-head-velocity neurons exhibited the strongest sensitivity to passive neck rotation and had signals that were best related to neck velocity. The results suggest that neck proprioceptive inputs play an important role in shaping the output of the primate vestibular nucleus and its contribution to posture, gaze and perception.

The contribution of the flocculus region of the cerebellum to horizontal gaze pursuit was studied in squirrel monkeys. When the head was free to move, the monkeys pursued targets with a combination of smooth eye and head movements; with the majority of the gaze velocity produced by smooth tracking head movements. In the accompanying study we reported that the flocculus region was necessary for cancellation of the vestibuloocular reflex (VOR) evoked by passive whole body rotation. The question addressed in this study was whether the flocculus region of the cerebellum also plays a role in canceling the VOR produced by active head movements during gaze pursuit. The firing behavior of 121 Purkinje (Pk) cells that were sensitive to horizontal smooth pursuit eye movements was studied. The sample included 66 eye velocity Pk cells and 55 gaze velocity Pk cells. All of the cells remained sensitive to smooth pursuit eye movements during combined eye and head tracking. Eye velocity Pk cells were insensitive to smooth pursuit head movements. Gaze velocity Pk cells were nearly as sensitive to active smooth pursuit head movements as they were passive whole body rotation; but they were less than half as sensitive ( approximately 43%) to smooth pursuit head movements as they were to smooth pursuit eye movements. Considered as a whole, the Pk cells in the flocculus region of the cerebellar cortex were <20% as sensitive to smooth pursuit head movements as they were to smooth pursuit eye movements, which suggests that this region does not produce signals sufficient to cancel the VOR during smooth head tracking. The comparative effect of injections of muscimol into the flocculus region on smooth pursuit eye and head movements was studied in two monkeys. Muscimol inactivation of the flocculus region profoundly affected smooth pursuit eye movements but had little effect on smooth pursuit head movements or on smooth tracking of visual targets when the head was free to move. We conclude that the signals produced by flocculus region Pk cells are neither necessary nor sufficient to cancel the VOR during gaze pursuit.

A series of studies were carried out to investigate the role of the cerebellar flocculus and ventral paraflocculus in the ability to voluntarily cancel the vestibuloocular reflex (VOR). Squirrel monkeys were trained to pursue moving visual targets and to fixate a head stationary or earth stationary target during passive whole body rotation (WBR). The firing behavior of 187 horizontal eye movement-related Purkinje (Pk) cells in the flocculus region was recorded during smooth pursuit eye movements and during WBR. Half of the Pk cells encountered were eye velocity Pk cells whose firing rates were related to eye movements during smooth pursuit and WBR. Their sensitivity to eye velocity during WBR was reduced when a visual target was not present, and their response to unpredictable steps in WBR was delayed by 80-100 ms, which suggests that eye movement sensitivity depended on visual feedback. They were insensitive to WBR when the VOR was canceled. The other half of the Purkinje cells encountered were sensitive to eye velocity during pursuit and to head velocity during VOR cancellation. They resembled the gaze velocity Pk cells previously described in rhesus monkeys. The head velocity signal tended to be less than half as large as the eye velocity-related signal and was observable at a short ( approximately 40 ms) latency when the head was unpredictably accelerated during ongoing VOR cancellation. Gaze and eye velocity type Pk cells were found to be intermixed throughout the ventral paraflocculus and flocculus. Most gaze velocity Pk cells (76%) were sensitive to ipsilateral eye and head velocity, but nearly half (48%) of the eye velocity Pk cells were sensitive to contralateral eye velocity. Thus the output of flocculus region is modified in two ways during cancellation of the VOR. Signals related to both ipsilateral and contralateral eye velocity are removed, and in approximately half of the cells a relatively weak head velocity signal is added. Unilateral injections of muscimol into the flocculus region had little effect on the gain of the VOR evoked either in the presence or absence of visual targets. However, ocular pursuit velocity and the ability to suppress the VOR by fixating a head stationary target were reduced by approximately 50%. These observations suggest that the flocculus region is an essential part of the neural substrate for both visual feedback-dependent and nonvisual mechanisms for canceling the VOR during passive head movements.

Effects of viewing distance on the responses of vestibular neurons to combined angular and linear vestibular stimulation. The firing behavior of 59 horizontal canal-related secondary vestibular neurons was studied in alert squirrel monkeys during the combined angular and linear vestibuloocular reflex (CVOR). The CVOR was evoked by positioning the animal's head 20 cm in front of, or behind, the axis of rotation during whole body rotation (0.7, 1.9, and 4.0 Hz). The effect of viewing distance was studied by having the monkeys fixate small targets that were either near (10 cm) or far (1.3-1.7 m) from the eyes. Most units (50/59) were sensitive to eye movements and were monosynaptically activated after electrical stimulation of the vestibular nerve (51/56 tested). The responses of eye movement-related units were significantly affected by viewing distance. The viewing distance-related change in response gain of many eye-head-velocity and burst-position units was comparable with the change in eye movement gain. On the other hand, position-vestibular-pause units were approximately half as sensitive to changes in viewing distance as were eye movements. The sensitivity of units to the linear vestibuloocular reflex (LVOR) was estimated by subtraction of angular vestibuloocular reflex (AVOR)-related responses recorded with the head in the center of the axis of rotation from CVOR responses. During far target viewing, unit sensitivity to linear translation was small, but during near target viewing the firing rate of many units was strongly modulated. The LVOR responses and viewing distance-related LVOR responses of most units were nearly in phase with linear head velocity. The signals generated by secondary vestibular units during voluntary cancellation of the AVOR and CVOR were comparable. However, unit sensitivity to linear translation and angular rotation were not well correlated either during far or near target viewing. Unit LVOR responses were also not well correlated with their sensitivity to smooth pursuit eye movements or their sensitivity to viewing distance during the AVOR. On the other hand there was a significant correlation between static eye position sensitivity and sensitivity to viewing distance. We conclude that secondary horizontal canal-related vestibuloocular pathways are an important part of the premotor neural substrate that produces the LVOR. The otolith sensory signals that appear on these pathways have been spatially and temporally transformed to match the angular eye movement commands required to stabilize images at different distances. We suggest that this transformation may be performed by the circuits related to temporal integration of the LVOR.

Effects of viewing distance on the responses of horizontal canal-related secondary vestibular neurons during angular head rotation. The eye movements generated by the horizontal canal-related angular vestibuloocular reflex (AVOR) depend on the distance of the image from the head and the axis of head rotation. The effects of viewing distance on the responses of 105 horizontal canal-related central vestibular neurons were examined in two squirrel monkeys that were trained to fixate small, earth-stationary targets at different distances (10 and 150 cm) from their eyes. The majority of these cells (77/105) were identified as secondary vestibular neurons by synaptic activation following electrical stimulation of the vestibular nerve. All of the viewing distance-sensitive units were also sensitive to eye movements in the absence of head movements. Some classes of eye movement-related vestibular units were more sensitive to viewing distance than others. For example, the average increase in rotational gain (discharge rate/head velocity) of position-vestibular-pause units was 20%, whereas the gain increase of eye-head-velocity units was 44%. The concomitant change in gain of the AVOR was 11%. Near viewing responses of units phase lagged the responses they generated during far target viewing by 6-25 degrees. A similar phase lag was not observed in either the near AVOR eye movements or in the firing behavior of burst-position units in the vestibular nuclei whose firing behavior was only related to eye movements. The viewing distance-related increase in the evoked eye movements and in the rotational gain of all unit classes declined progressively as stimulus frequency increased from 0.7 to 4.0 Hz. When monkeys canceled their VOR by fixating head-stationary targets, the responses recorded during near and far target viewing were comparable. However, the viewing distance-related response changes exhibited by central units were not directly attributable to the eye movement signals they generated. Subtraction of static eye position signals reduced, but did not abolish viewing distance gain changes in most units. Smooth pursuit eye velocity sensitivity and viewing distance sensitivity were not well correlated. We conclude that the central premotor pathways that mediate the AVOR also mediate viewing distance-related changes in the reflex. Because irregular vestibular nerve afferents are necessary for viewing distance-related gain changes in the AVOR, we suggest that a central estimate of viewing distance is used to parametrically modify vestibular afferent inputs to secondary vestibuloocular reflex pathways.

The firing behavior of seven antidromically identified ascending tract of Deiters (ATD) neurons was recorded in one alert squirrel monkey trained to pursue moving targets and to fixate visual targets at different distances from the head during whole body rotation. 2. ATD cells generated signals related to contralateral horizontal smooth pursuit eye movements and to ipsilateral angular and linear head velocity. Most ATD neurons reversed the direction of their response to head rotation when the vestibulo-ocular reflex was canceled by fixation of a head stationary target. 3. ATD unit gains in respect to linear head velocity increased dramatically (> 4x) when a near, earth stationary target (10 cm from the eyes) was fixated, compared to the response recorded during fixation of a far target (130 to 170 cm from the eyes). Since the viewing distance related changes in the responses of ATD neurons closely parallel the changes in the responses of the eyes, the ATD appears to be an important premotor pathway for producing viewing distance related changes in the gain of the vestibulo-ocular reflex.

The discharge of neurons in the vestibular nuclei was recorded in alert squirrel monkeys while they were being sinusoidally rotated at 2 Hz. Type I position-vestibular-pause (PVP I) and vestibular-only (V I) neurons, as well as a smaller number of other type I and type II eye-plus-vestibular neurons were studied. Many of the neurons were monosynaptically related to the ipsilateral vestibular nerve. Eye-position and vestibular components of the rotation response were separated by multiple regression. Anodal currents, simultaneously delivered to both ears, were used to eliminate the head-rotation signals of irregularly discharging (I) vestibular-nerve afferents, presumably without affecting the corresponding signals of regularly discharging (R) afferents. R and I inputs to individual central neurons were determined by comparing rotation responses with and without the anodal currents. The bilateral currents, while reducing the background discharge of all types of neurons, did not affect the mean vestibular gain or phase calculated from a population of PVP I neurons or from a mixed population consisting of all type I units. From this result, it is concluded that I inputs are canceled at the level of secondary neurons. The cancellation may explain why the ablating currents do not affect the gain and phase of the vestibulo-ocular reflex. While cancellation was nearly perfect on a population basis, it was less so in individual neurons. For some neurons, the ablating currents decreased vestibular gain, while for other neurons the vestibular gain was increased. The former neurons are interpreted as receiving a net excitatory (I-EXC) I input, the latter neurons, a net inhibitory (I-INH) input. When compared with the corresponding R inputs, the I inputs were usually small and phase advanced. Phase advances were larger for I-EXC than for I-INH inputs. The sign and magnitude of the I inputs were unrelated to other discharge properties of individual neurons, including discharge regularity and the phase of vestibular responses measured in the absence of the ablating currents. Unilateral currents were used to assess the efficacy of ipsilateral and contralateral pathways. Ipsilateral pathways were responsible for almost all of the effects seen with bilateral currents. The results suggest that the vestibular signals carried by central neurons, even by those neurons receiving a monosynaptic vestibular-nerve input, are modified by polysynaptic pathways.

Study Objective: To determine whether long-term oral diuretic therapy would improve the pulmonary function of preterm infants with bronchopulmonary dysplasia., Design: Randomized, double-blind, placebo-controlled study., Setting: Level III intensive care nursery., Intervention: We randomly selected 43 stable patients with oxygen-dependent bronchopulmonary dysplasia to receive either orally administered spironolactone and chlorothiazide or placebo. These drugs were continued until the patients no longer required supplemental oxygen. Both groups received furosemide as needed., Measurements and Results: Each infant had pulmonary function tests at study entry, 4 weeks after study entry, 1 week and 8 weeks after being weaned to room air and off study drugs, and at 1 year of corrected age. Pulmonary function tests include dynamic pulmonary compliance, airway resistance, thoracic gas volume, and maximal expiratory flow at functional residual capacity; most of the infants had functional residual capacity measured. Between the first and second pulmonary function tests (while the infants were receiving diuretic or placebo), the infants in the diuretic group had a significant improvement in dynamic pulmonary compliance (46%; p < 0.001) and airway resistance (31%; p < 0.05); there were no changes in compliance or resistance in the placebo group. Although patients in both the diuretic and the placebo groups required progressively less supplemental oxygen, by 4 weeks after study entry the patients in the diuretic group needed less supplemental oxygen than did those in the placebo group (p < 0.01). There were no significant differences in results of serial pulmonary function tests in either group after discontinuation of diuretic therapy. Despite the significant differences in pulmonary function between the two groups, there was no significant difference between them in the total number of days that supplemental oxygen was required. Significantly more infantsin the placebo group received more than 10 doses of furosemide on an as-needed basis., Conclusions: Long-term diuretic therapy in stable infants with oxygen-dependent bronchopulmonary dysplasia, after extubation, improves their pulmonary function and decreases their fractional inspired oxygen requirement, but does not decrease the number of days that they require supplemental oxygen. The improvement in pulmonary function associated with diuretic therapy is not maintained after treatment is discontinued.

Neurons in the vestibular nuclei and the prepositus nucleus exhibited several different types of changes in their firing behavior during voluntary cancellation of the horizontal VOR. The head velocity sensitivity of type I position-vestibular-pause neurons was reduced during cancellation, while type II vestibular neurons exhibit an increase in their sensitivity. The firing behavior of burst tonic neurons in the medial vestibular nucleus, the prepositus nucleus, like the cells in the abducens nucleus, was closely related to the eye movements generated when the VOR is cancelled. Other cells in the PH and MVN respond primarily to smooth pursuit eye movements. We suggest that the behavior of abducens neurons during the VOR and during VOR cancellation can be explained if they receive inputs from PVP neurons, burst tonic neurons, and smooth pursuit neurons.

Estimation of lung volumes by conventional methods in sick infants is technically difficult and is the subject of controversy. In this study, we compared both thoracic gas volume (TGV), measured with an infant whole body plethysmograph, and functional residual capacity (FRC), determined by the nitrogen washout technique, to planimetric measurements of anteroposterior chest radiographs in 26 infants with bronchopulmonary dysplasia (BPD). The tidal volume (TV) of each patient was added to TGV and FRC because these were measured at the end of expiration whereas chest radiographs were taken at the end of spontaneous inspiration. The regression equations expressing the relationships between TGV and right+left lung field areas [A+B], and between FRC and lung areas are expressed as follows: [TGV+TV](mL) = 3.3 mL/cm2 x [A+B] cm2 + 24 mL and [FRC+TV](mL) = 3.5 mL/cm2 x [A+B] cm2 - 13.5 mL. Correlation coefficients of 0.9 and 0.7 for TGV and FRC, respectively, suggest a stronger correlation between TGV and lung areas than between FRC and lung areas. Lung areas measured by planimetry correlate closely with physiological measurement of lung volumes. We conclude that the planimetric method is an inexpensive and reliable technique for estimating lung volumes in young infants with BPD when chest radiographs are available.

Uterine adnexal torsion and infarction is described in a 12-year-old girl who, six weeks later, suffered a contralateral recurrence, rendering her sterile. This is on the second known and reported case of this unusual sequence of events. The question of performing a prophylactic oophoropexy is addressed. A high index of suspicion and early diagnosis are mandatory in this condition to preserve reproductive function.

Purkinje (Pk) cells in the cat cerebellum were intracellularly labeled with horseradish peroxidase (HRP). Both light and electron microscopy were used to determine (1) the degree to which the morphological detail of a neuron is revealed and (2) whether HRP labeled neurons maintain normal morphological and cytological characteristics. The morphological detail obtained with intracellular labeling was comparable to that found in Golgi impregnated material. The reaction product was found in the soma, dendrites, dendritic spines and in the axon including the fine axonal collaterals. Neurons which appeared normal under the light microscope were analyzed with the electron microscope. The ultrastructural characteristics of these Pk cells were similar to those observed in previous transmission electron microscopic studies. In many cases, however, there were obvious alterations in the morphology of the somata, dendrites and axonal collaterals of the injected neurons. These alterations included beading or clumping of the secondary and tertiary dendrites, an absence of labeled spins and axonal collaterals, and distortions of the soma membrane. Post injection survival time injection charge and amplitude of the climbing fiber response recorded pre-injection were analyzed in order to determine if they could be correlated with the morphological integrity of the neuron. Our data did not reveal an association between these and the morphological condition of the Pk cell. Possible reasons for this lack of association are discussed.

The continuous, noninvasive estimation of arterial carbon dioxide tension (PaCO2) by heated skin surface electrodes has recently become available for pediatric patients. Skin surface (PsCO2) electrodes can enhance the safety of procedures such as intubation, bronchoscopy, ventilator changes, sleep studies, or measurement of the ventilatory response to CO2 or hypoxia. However, clinical situations that include rapid changes in PaCO2 demand knowledge of the in vivo response time. We compared the response of a heated PsCO2 electrode to end tidal CO2 (PetCO2) during abrupt changes in inspired CO2 from room air to 7% CO2 and back to room air. We obtained 54 curves on nine healthy subjects. There was an initial lag time with less than a 10% change in PsCO2. Then PsCO2 approached PetCO2 exponentially. For subjects at rest changing from breathing room air to 7% CO2, the initial lag time was 40 +/- 2 seconds and the 50% response time of the exponential portion was 46 +/- 3 seconds. Thus, it took 86 seconds for the electrode to record a 60% response to an abrupt increase in inspired CO2. The initial lag and 50% response time were considerably shorter during exercise (30 +/- 2 and 33 +/- 2 seconds) and even shorter when switched from breathing 7% CO2 to room air (23 +/- 2 and 21 +/- 2 seconds). Exercise did not further reduce the response time when CO2 was initially elevated, suggesting the faster response time was due to vasodilation of the skin due to elevated CO2.(ABSTRACT TRUNCATED AT 250 WORDS)

The input to the nucleus interpositus anterior (NIA) of the cat from the inferior olive (IO) was studied by stimulating the IO while recording intracellularly from the NIA, and by the retrograde transport of horseradish peroxidase (HRP). Stimulation of the IO evoked monosynaptic EPSPs in NIA neurons. The cells labeled in the IO following electrophoretic and pressure injection of HRP into NIA were located in the rostral parts of the dorsal and medial accessory olive. Stimulation of the IO also polysynaptically evoked an IPSP and a late disinhibitory depolarization. Data were presented which indicated that these potentials were mediated by the Purkinje cells of the cerebellar cortex.

The primary goal of this investigation was to identify the areas of the brainstem and cerebellum that provide afferent projections to the nucleus prepositus hypoglossi in primates. After horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) was injected into the prepositus in squirrel monkeys (Saimiri sciureus), the largest populations of retrogradely labeled neurons were found in the vestibular nuclei, the contralateral perihypoglossal nuclei, and the medullary and pontine reticular formation. Unlike the cat, the prepositus in Saimiri received substantial projections from the nucleus raphe dorsalis and the central mesencephalic reticular formation, whereas few or no labeled cells were found in the cerebellar cortex, the superior colliculus, or the nucleus reticularis tegmenti pontis. By comparing the afferents to the prepositus with those to the abducens nucleus, we found that all regions projecting to the abducens also projected to the prepositus, without exception. Anterogradely transported WGA-HRP showed that the major brainstem recipients of prepositus efferents were the vestibular and perihypoglossal nuclei, the inferior olive, the medullary reticular formation, and the extraocular motor nuclei. In the cerebellar cortex, the prepositus projected to restricted regions of crura I and II as well as the caudal vermis and vestibulocerebellum. The many parts of the oculomotor system receiving input from the prepositus and the parallel innervation of the prepositus and the abducens by a large number of premotor centers lend support to the hypothesis that the prepositus may distribute an efference copy of motor activity, and may also play an important role in the process of neural integration.

The heterogeneous cytoarchitecture of nucleus prepositus hypoglossi and its multiplicity of afferent and efferent connections to oculomotor structures are described. They are more than adequate to account for a role in eye and head movements: it is suggested that they may provide the neuroanatomical basis for an efference copy signal of eye position, which would also be important in gaze-holding.

The potential usefulness of the auditory-evoked brain stem potentials in audiological assessment has been the subject of increased clinical enquiry. Several requirements need to be met by any response parameter if it is to be clinically useful: parameters should show a clear, and ideally simple, relationship with stimulus intensity; they should be stable within any subject under fixed stimulation conditions and intersubject variability within any clinical group should be small. Response latency has been shown to satisfy the first two of these conditions. However, intersubject variability has been less clearly defined. In a sample of normal controls we have found that the standard deviation of latency at any specific intensity was substantial, exceeding the difference found between mean responses at neighbouring intensities of auditory stimulation. In an investigation of the origins of this variability we have found a clear gender difference, maximal for later components in which the male responses were significantly later than the female responses. The clinical significance of this finding can be seen in the latency intensity input/output function. By treating each gender group separately, intersubject variance values were reduced by approximately 40% compared with the total group variance, so enhancing the usefulness of latency as a parameter in the objective assessment of auditory function.

Inputs to the nucleus interpositus anterior (NIA) of the cat from precerebellar nuclei which are thought to give rise to mossy fibers were studied using electrophysiological and anatomical techniques. Stimulation of one of these precerebellar nuclei, the lateral reticular nucleus (LRN) evoked monosynaptic EPSPs in NIA neurons. These EPSPs were followed by polysynaptic IPSPs and late depolarization mediated by the response of the cerebellar cortex. Similar responses were occasionally seen following stimulation of the brachium pontis (BP). When horseradish peroxidase was injected into the NIA, labeled cells were found in the magnocellular and parvicellular LRN, the external cuneate nucleus (ECN), the pontine nuclei and the perihypoglossal nuclei. There was no evidence for a direct projection of the nucleus reticularis pontis to the NIA. It was suggested that most of the tonic excitation of NIA neurons is provided by the LRN and ECN.