Periaqueductal gray and the region of the paralemniscal area have different functions in the control of vocalization in the neotropical bat, Phyllostomus discolor.

The periaqueductal gray matter and the region of the paralemniscal area were neuroanatomically delineated in the brain of the neotropical bat Phyllostomus discolor[Wagner (1843) Arch. Naturgesch., 9, 365-368] and were probed with electrical microstimulation for eliciting vocalizations. In a well-delimited rostral portion of the periaqueductal gray exclusively, communication calls could be triggered at low stimulation currents. Communication calls as well as echolocation calls could be elicited at the dorsal and ventral edges of this area. Pharmacological stimulation with microdialysed kainic acid in this particular periaqueductal gray area demonstrated that neurons and not fibres of passage are activated for triggering vocalization. Solely echolocation calls were emitted upon electrical microstimulation or with microdialysed kainic acid in the region of the paralemniscal area. The periaqueductal gray appears to be involved in vocal pathways that control both communication calls and echolocation calls, while the region of the paralemniscal area seems to be specialized for control of echolocation calls only. Respiration is similarly influenced by stimulation in the periaqueductal gray and the region of the paralemniscal area. Periaqueductal gray and paralemniscal area interact differently with the final common pathway for vocalization, and may represent different functional organization in the vocal controlling pathways for communication calls and echolocation calls.

Stimulation of autologous antitumor T-cell responses against medullary thyroid carcinoma using tumor lysate-pulsed dendritic cells.

Dendritic cells (DCs) have attracted wide interest because of their unique capacity to elicit primary and secondary antitumor responses. We have generated autologous tumor lysate-pulsed DCs from three patients with medullary thyroid carcinoma (MTC) and tested them for their ability to stimulate cytotoxic T-cell responses against autologous MTC tumor cells in vitro. The aim of our investigations was to evaluate the potential efficacy of DC-based immunotherapy in patients with MTC. DCs were generated from peripheral blood monocytes using GM-CSF and IL-4 (immature DCs) or GM-CSF, IL-4, and TNFalpha (mature DCs). Our results indicate that mature tumor lysate-pulsed DCs are able to elicit a human leukocyte antigen class I-restricted cytotoxic T-cell response against autologous MTC tumor cells, whereas immature tumor lysate-pulsed DCs do not stimulate significant antitumor activity. We feel that our data may be relevant for future clinical trials of active immunotherapy using tumor lysate-pulsed DCs in patients with MTC who have residual or distant disease after surgical treatment. The fact that mature DCs displayed a substantially higher capacity to stimulate autologous antitumor T-cell responses than immature DCs underlines the importance of a maturation step in immunotherapy protocols based on DCs.

Cortical representation of acoustic motion in the rufous horseshoe bat, Rhinolophus rouxi.

Responses of neurons to apparent auditory motion in the azimuth were recorded in three different fields of auditory cortex of the rufous horseshoe bat. Motion was simulated using successive stimuli with dynamically changing interaural intensity differences presented via earphones. Seventy-one percent of sampled neurons were motion-direction-sensitive. Two types of responses could be distinguished. Thirty-four percent of neurons showed a directional preference exhibiting stronger responses to one direction of motion. Fifty-seven percent of neurons responded with a shift of spatial receptive field position depending on direction of motion. Both effects could occur in the same neuron depending on the parameters of apparent motion. Most neurons with contralateral receptive fields exhibited directional preference only with motion entering the receptive field from the opposite direction. Receptive field shifts were opposite to the direction of motion. Specific combinations of spatiotemporal parameters determined the motion-direction-sensitive responses. Velocity was not encoded as a specific parameter. Temporal parameters of motion and azimuth position of the moving sound source were differentially encoded by neurons in different fields of auditory cortex. Neurons with a directional preference in the dorsal fields can encode motion with short interpulse intervals, whereas direction-preferring neurons in the primary field can best encode motion with medium interpulse intervals. Furthermore, neurons with a directional preference in the dorsal fields are specialized for encoding motion in the midfield of azimuth, whereas direction-preferring neurons in the primary field can encode motion in lateral positions. The results suggest that motion information is differentially processed in different fields of the auditory cortex of the rufous horseshoe bat.

Motion processing in the auditory cortex of the rufous horseshoe bat: role of GABAergic inhibition.

This study examined the influence of inhibition on motion-direction-sensitive responses of neurons in the dorsal fields of auditory cortex of the rufous horseshoe bat. Responses to auditory apparent motion stimuli were recorded extracellularly from neurons while microiontophoretically applying gamma-aminobutyric acid (GABA) and the GABAA receptor antagonist bicuculline methiodide (BMI). Neurons could respond with a directional preference exhibiting stronger responses to one direction of motion or a shift of receptive field (RF) borders depending on direction of motion. BMI influenced the motion direction sensitivity of 53% of neurons. In 21% of neurons the motion-direction sensitivity was decreased by BMI by decreasing either directional preference or RF shift. In neurons with a directional preference, BMI increased the spike number for the preferred direction by a similar amount as for the nonpreferred direction. Thus, inhibition was not direction specific. BMI increased motion-direction sensitivity by either increasing directional preference or magnitude of RF shifts in 22% of neurons. Ten percent of neurons changed their response from a RF shift to a directional preference under BMI. In these neurons, the observed effects could often be better explained by adaptation of excitation rather than inhibition. The results suggest, that adaptation of excitation, as well as cortex specific GABAergic inhibition, contribute to motion-direction sensitivity in the auditory cortex of the rufous horseshoe bat.

The central acoustic tract and audio-vocal coupling in the horseshoe bat, Rhinolophus rouxi.

Doppler shift compensation (DSC) behaviour in horseshoe bats is a remarkable example of sensorimotor feedback that stabilizes the echo frequency at the bat's optimum hearing range regardless of motion-induced frequency shifts in the echoes. Searching for a related neural interface, the nucleus of the central acoustic tract (NCAT) was investigated in the echolocating horseshoe bat, Rhinolophus rouxi, using various neurophysiological and tracer methods. The NCAT receives bilateral auditory input from the cochlear nuclei and sends projections to regions outside the classical acoustic pathway like the pretectal area or the superior colliculus. The binaural input is excitatory from the contralateral and inhibitory from the ipsilateral ear to 53% of the units, and auditory responses were biased to frontal and contralateral directions. The best frequencies of NCAT neurons match a narrow range above the main frequency component of the bat's species-specific echolocation call (62% of the units), and the neurons exhibit extremely sharp tuning (Q10dB up to 632). DSC is degraded by unilateral electrical or pharmacological microstimulation of the NCAT, and heavily impaired by unilateral lesion of the region. Altogether, the efferents of the NCAT to prevocal areas, the tuning of its neurons to the DSC-relevant echo frequency range, and the possibility to affect DSC by manipulation of the NCAT, support the assumption that the nucleus plays an important role in audio-vocal control in the horseshoe bat.

Gluconacetobacter entanii sp. nov., isolated from submerged high-acid industrial vinegar fermentations.

Acetic acid bacteria have been isolated from submerged high-acid spirit vinegar fermentations in the Southern part of Germany. Four strains (LTH 4560T, LTH 4341, LTH 4551 and LTH 4637) were characterized in more detail and it was revealed that they have in common certain properties such as requirement of acetic acid, ethanol and glucose for growth, and no over-oxidation of acetate. Growth occurs only at total concentrations (sum of acetic acid and ethanol) exceeding 6.0%. A method for their preservation was developed. Comparative analysis of the 16S rRNA revealed sequence similarities of >99% between strain LTH 4560T and the type strains of the related species Gluconacetobacter hansenii. However, low levels of DNA relatedness (<41 %) were determined in DNA-DNA similarity studies. In addition, specific physiological characteristics permitted a clear identification of the strains within established species of acetic acid bacteria. The strains could also be differentiated on the basis of the distribution of IS element 1031 C within the chromosome. Based on these results, the new species Gluconacetobacter entanii sp. nov. is proposed for strain LTH 4560T ( = DSM 13536T). A 16S-rRNA-targeted oligonucleotide probe was constructed that was specific for G. entanii, and the phylogenetic position of the new species was derived from a 16S-rRNA-based tree.

Binaural influences on Doppler shift compensation of the horseshoe bat Rhinolophus rouxi.

The flying horseshoe bat Rhinolophus rouxi compensates for Doppler shifts in echoes of their orientation pulses. By lowering the frequency of subsequent calls the echo's constant frequency is stabilized at the so-called reference frequency centered in a narrow and sensitive cochlear filter. This audio-vocal behaviour is known as Doppler shift compensation. To investigate whether the bats depend on binaural cues when compensating, three animals were tested for compensation on a swing before and after unilateral deafening. In each case compensation was severely impaired by unilateral deafening. Individual animals' compensation amplitude was reduced to 28-48% of the preoperational compensation of a +1.8 kHz shift. Doppler shift compensation performance did not recover to control levels during the observed period of 24 h after surgery. In contrast, unilateral middle ear removal which induces a unilateral auditory threshold increase of 9-14 dB does not impair compensation performance on the swing. To mimick Doppler shifts in a fixed setup, the frequencies of recorded echolocation calls were experimentally shifted between 0 and +2 kHz and played back via earphones to six animals. The bats completely compensated the experimental shifts only as long as the interaural intensity difference of the playback did not exceed 20 dB. No animal compensated with monaural playback.

Audiovocal behavior of Doppler-shift compensation in the horseshoe bat survives bilateral lesion of the paralemniscal tegmental area.

The role of the paralemniscal tegmental area of the horseshoe bat, Rhinolophus rouxi, in the control of vocalization and Doppler-shift compensation was investigated using electrical and pharmacological stimulation and lesioning techniques. The paralemniscal tegmental area is situated in the dorsolateral tegmentum ventral to the inferior colliculus and rostral and medial to the dorsal and intermediate nuclei of the lateral lemniscus. Vocalizations indistinguishable from spontaneously uttered calls can be elicited with both electrical and pharmacological stimulation methods, demonstrating that the stimulation of neural elements within the area and not fibers passing through the area are responsible for the stimulated call emission. The audiovocal feedback system for Doppler-shift compensation was also investigated. Doppler-shift compensation adjusts the frequency of the emitted calls according to the increases in the frequency of the echoes that are normally encountered in flying bats. Bats compensate for Doppler shifts not only under natural conditions but also when echoes are played back to the bat following spontaneous vocalizations or vocalizations induced by electrical or pharmacological stimulation of the investigated brain area. Unilateral electrolytic lesions of the paralemniscal tegmental area did not impair the ability to evoke vocalizations with electrical stimulation of the unlesioned side. The calls had exactly the same structure and frequency composition as those emitted prior to lesioning. Unilateral lesions also did not impair Doppler-shift compensation performance. After bilateral lesioning of the paralemniscal area, vocalizations could not be evoked with electrical stimulation. However, normal calls were emitted spontaneously and Doppler-shift compensation during spontaneous call emission was unaltered compared with the intact condition. The paralemniscal tegmental area is therefore not an audiovocal feedback system required for Doppler-shift compensation, but rather a brain area whose stimulation and activation is sufficient but not necessary for call emission. It is also not directly involved in the control of spectral parameters of vocalization but contributes to the control of the occurrence of vocal output.

Medial superior olive in the free-tailed bat: response to pure tones and amplitude-modulated tones.

In mammals with good low-frequency hearing and a moderate to large interear distance, neurons in the medial superior olive (MSO) are sensitive to interaural time differences (ITDs). Most small mammals, however, do not hear low frequencies and do not experience significant ITDs, suggesting that their MSOs participate in functions other than ITD coding. In one bat species, the mustached bat, the MSO is a functionally monaural nucleus, acting as a low-pass filter for the rate of sinusoidally amplitude-modulated (SAM) stimuli. We investigated whether the more typical binaural MSO of the MExican free-tailed bat also acts as an SAM filter. We recorded from 60 MSO neurons with their best frequencies covering the entire audiogram of this bat. The majority revealed bilateral excitation and indirect evidence for inhibition (EI/EI; 55%). The remaining neurons exhibited reduced inputs, mostly lacking ipsilateral inputs (28% I/EI; 12% O/EI; 5% EI/O). Most neurons (64%) responded with a phasic discharge to pure tones; the remaining neurons exhibited an additional sustained component. For stimulation with pure tones, two thirds of the cells exhibited monotonic rate-level functions for ipsilateral, contralateral, or binaural stimulation. In contrast, nearly all neurons exhibited nonmonotonic rate-level functions when tested with SAM stimuli. Eighty-eight percent of the neurons responded with a phase-locked discharge to SAM stimuli at low modulation rates and exhibited low-pass filter characteristics in the modulation transfer function (MTF) for ipsilateral, contralateral, and binaural stimulation. The MTF for ipsilateral stimulation usually did not match that for contralateral stimulation. Introducing interaural intensity differences (IIDs) changed the MTF in unpredictable ways. We also found that responses to SAMs depended on the carrier frequency. In some neurons we measured the time course of the ipsilaterally and contralaterally evoked inhibition by presenting brief frequency-modulated sweeps at different ITDs. The duration and timing of inhibition could be related to the SAM cutoff for binaural stimulation. We conclude that the response of the MSO in the free-tailed bat is created by a complex interaction of inhibition and excitation. The different time constants of inputs create a low-pass filter for SAM stimuli. However, the MSO output is an integrated response to the temporal structure of a stimulus as well as its azimuthal position, i.e., IIDs. There are no in vivo results concerning filter characteristics in a "classical" MSO, but our data confirm an earlier speculation about this interdependence based on data accessed from a gerbil brain slice preparation.

A cheap earphone for small animals with good frequency response in the ultrasonic frequency range.

A new type of earphone for binaural stimulation in small animals is described. The characteristic features are: (1) small, 8 mm diameter, can be miniaturised further; (2) cheap, uses no expensive condenser microphone capsule, material costs less than 20 dollars; (3) frequency response flat within 6 dB between 10 kHz and 120 kHz, within 10 dB up to 200 kHz; (4) harmonic distortions at levels of the fundamental frequency below 75 dB SPL is below - 34 dB at worst case (10 kHz); and (5) due to the low price the most stable earphones optimally paired for dichotic stimulation can be selected by screening a number of individual specimen.

Significance of the paralemniscal tegmental area for audio-motor control in the moustached bat, Pteronotus p. parnellii: the afferent off efferent connections of the paralemniscal area.

The paralemniscal tegmental area has been determined in the brain of the New World moustached bat, Pteronotus p. parnellii, by electrical microstimulation eliciting echolocation calls and pinna movements. It is located in the dorsal tegmentum rostral and medial to the dorsal nucleus of the lateral lemniscus and is characterized by medium sized and large neurons. Tracer injections (WGA-HRP) showed that the most intense input to the paralemniscal tegmental area originates in the intermediate and deep layers of the homolateral superior colliculus. The strong projections from the ipsi- and contralateral nucleus praepositus hypoglossus most probably contributes vestibular information. Further inputs in descending order of intensity are from the substantia nigra, the contralateral paralemniscal tegmental area, the putamen, the ventral reticular formation in its lateral portions, the medial cerebellar nucleus and the dorsal reticular formation. Efferent projections of the paralemniscal tegmental area reach the putamen bilaterally, the nucleus accumbens and other parts of the basal ganglia, the pretectal area, the substantia nigra, the intermediate and deep layers of the superior colliculus bilaterally and the tegmental area ventral to it. Connections to the dorsal part of the periaqueductal grey, the cuneiform nucleus and the parabrachial region are important in the context of vocal control, whereas projections to the medial portion of the contralateral facial nucleus may interfere with the control of pinna movement. The findings suggest that the paralemniscal tegmental area is involved in audio-motor control of vocalization and pinna movements in bats; connectional and functional similarities and disparities to tegmental regions described in other mammals are discussed.

Neural delays shape selectivity to interaural intensity differences in the lateral superior olive.

Neurons in the lateral superior olive (LSO) respond selectively to interaural intensity differences (IIDs), one of the chief cues used to localize sounds in space. LSO cells are innervated in a characteristic pattern: they receive an excitatory input from the ipsilateral ear and an inhibitory input from the contralateral ear. Consistent with this pattern, LSO cells generally are excited by sounds that are more intense at the ipsilateral ear and inhibited by sounds that are more intense at the contralateral ear. Despite their relatively homogeneous pattern of innervation, IID selectivity varies substantially from cell to cell, such that selectivities are distributed over the range of IIDs that would be encountered in nature. For some time, researchers have speculated that the relative timing of the excitatory and inhibitory inputs to an LSO cell might shape IID selectivity. To test this hypothesis, we recorded from 50 LSO cells in the free-tailed bat while presenting stimuli that varied in interaural intensity and in interaural time of arrival. The results suggest that, for more than half of the cells, the latency of inhibition was several hundred microseconds longer than the latency of excitation. Increasing the intensity to the inhibitory ear shortened the latency of inhibition and brought the timing of the inputs from the two ears into register. Thus, a neural delay of the inhibition helped to define the IID selectivity of these cells, accounting for a significant part of the variation in selectivity among LSO cells.

Auditory cortex of the rufous horseshoe bat: 1. Physiological response properties to acoustic stimuli and vocalizations and the topographical distribution of neurons.

The extent and functional subdivisions of the auditory cortex in the echolocating horseshoe bat, Rhinolophus rouxi, were neurophysiologically investigated and compared to neuroarchitectural boundaries and projection fields from connectional investigations. The primary auditory field shows clear tonotopic organization with best frequencies increasing in the caudorostral direction. The frequencies near the bat's resting frequency are largely over-represented, occupying six to 12 times more neural space per kHz than in the lower frequency range. Adjacent to the rostral high-frequency portion of the primary cortical field, a second tonotopically organized field extends dorsally with decreasing best frequencies. Because of the reversed tonotopic gradient and the consistent responses of the neurons, the field is comparable to the anterior auditory field in other mammals. A third tonotopic trend for medium and low best frequencies is found dorsal to the caudal primary field. This area is considered to correspond to the dorsoposterior field in other mammals. Cortical neurons had different response properties and often preferences for distinct stimulus types. Narrowly tuned neurons (Q10dB > 20) were found in the rostral portion of the primary field, the anterior auditory field and in the posterior dorsal field. Neurons with double-peaked tuning curves were absent in the primary area, but occurred throughout the dorsal fields. Vocalization elicited most effectively neurons in the anterior auditory field. Exclusive response to pure tones was found in neurons of the rostral dorsal field. Neurons preferring sinusoidal frequency modulations were located in the primary field and the anterior and posterior dorsal fields adjacent to the primary area. Linear frequency modulations optimally activated only neurons of the dorsal part of the dorsal field. Noise-selective neurons were found in the dorsal fields bordering the primary area and the extreme caudal edge of the primary field. The data provide a survey of the functional organization of the horseshoe bat's auditory cortex in real coordinates with the support of cytoarchitectural boundaries and connectional data.

Anatomy and projection patterns of the superior olivary complex in the Mexican free-tailed bat, Tadarida brasiliensis mexicana.

The superior olivary complex (SOC) is the first station in the ascending auditory pathway that receives binaural projections. Two of the principal nuclei, the lateral superior olive (LSO) and the medial superior olive (MSO), are major sources of ascending projections to the inferior colliculus. Whereas almost all mammals have an LSO, it has traditionally been thought that only animals that hear low frequencies have an MSO. Recent reports, however, suggest that the medial part of the SOC in bats is highly variable and that at least some bats have a well-developed MSO. Thus, the main goal of this study was to evaluate the cytoarchitecture and connections of the principal superior olivary nuclei of the Mexican free-tailed bat, with specific attention directed at the MSO. Cell and fiber stained material revealed that the LSO and the medial nucleus of the trapezoid body (MNTB) are similar to those described for other mammals. There are two medial nuclei we refer to as dorsomedial periolivary nucleus (DMPO) and MSO. Tracer experiments exhibited that the DMPO receives bilateral projections from the cochlear nucleus, and additional projections from the ipsilateral MNTB. The DMPO sends a strong projection to the ipsilateral inferior colliculus. Positive staining for acetylcholinesterase indicates that the DMPO is a part of the olivocochlear system, as it is in other animals. The MSO in the free-tailed bat meets many of the criteria that traditionally define this nucleus. These include the presence of bipolar and multipolar principal cells, bilateral innervation from the cochlear nucleus, a strong projection from the ipsilateral MNTB, and the absence of cholinergic cells. The major difference from traditional MSO features is that it projects bilaterally to the inferior colliculus. Approximately 30% of its cells provide collateral projections to the colliculi on both sides. Functional implications of the MSO for the free-tailed bat are considered in the Discussion.

The bovine papillomavirus type 1 genome contains multiple loci of static DNA bending, but bends are absent from the functional origin of replication.

Twenty-four overlapping restriction fragments spanning the entire bovine papillomavirus type 1 (BPV-1) genome were analyzed by electrophoresis to determine the extent of static DNA bending in the BPV-1 genome. Thirteen of 24 fragments contained static bends. Based on known locations of previously mapped bend loci and the overlapping pattern of these 13 fragments, we estimate that there are 8-11 distinct static bend loci in the BPV-1 genome. The bend loci were not uniformly distributed on the genome and with one exception, were clustered from nucleotides 5816 to 2621 on the BPV-1 map. This portion of the BPV-1 genome contains most of the transcriptional regulatory sequences as well as the origin of replication. The concordance between the genomic distribution of DNA bends and cis-active elements is consistent with the possibility that bent sequences may contribute to the function of at least some of these elements. However, unlike SV40, there was no static bend at that functional origin of replication for BPV-1. The nearest bends to the origin were approximately 120 bp to the 5' side and 300 bp to the 3' side. As both of these bends were outside of the sequences required for origin function, it is unlikely that static bending plays a critical role in BPV-1 replication.

DNA binding specificity of the bovine papillomavirus E1 protein is determined by sequences contained within an 18-base-pair inverted repeat element at the origin of replication.

Bovine papillomavirus type 1 (BPV-1) DNA replicates episomally and requires two virally expressed proteins, E1 and E2, for this process. Both proteins bind to the BPV-1 genome in the region that functions as the origin of replication. The binding sequences for the E2 protein have been characterized previously, but little is known about critical sequence requirements for E1 binding. Using a bacterially expressed E1 fusion protein, we examined binding of the BPV-1 E1 protein to the origin region. E1 strongly protected a 28-bp segment of the origin (nucleotides 7932 to 15) from both DNase I and exonuclease III digestion. Additional exonuclease III protection was observed beyond the core region on both the 5' and 3' sides, suggesting that E1 interacted with more distal sequences as well. Within the 28-bp protected core, there were two overlapping imperfect inverted repeats (IR), one of 27 bp and one of 18 bp. We show that sequences within the smaller, 18-bp IR element were sufficient for specific recognition of DNA by E1 and that additional BPV-1 sequences beyond the 18-bp IR element did not significantly increase origin binding by E1 protein. While the 18-bp IR element contained sequences sufficient for specific binding by E1, E1 did not form a stable complex with just the isolated 18-bp element. Formation of a detectable E1-DNA complex required that the 18-bp IR be flanked by additional DNA sequences. Furthermore, binding of E1 to DNA containing the 18-bp IR increased as a function of overall increasing fragment length. We conclude that E1-DNA interactions outside the boundaries of the 18-bp IR are important for thermodynamic stabilization of the E1-DNA complex. However, since the flanking sequences need not be derived from BPV-1, these distal E1-DNA interactions are not sequence specific. Comparison of the 18-bp IR from BPV-1 with the corresponding region from other papillomaviruses revealed a symmetric conserved consensus sequence, T-RY--TTAA--RY-A, that may reflect the specific nucleotides critical for E1-DNA recognition.

Facilitation and Delay Sensitivity of Auditory Cortex Neurons in CF - FM Bats, Rhinolophus rouxi and Pteronotus p.parnellii.

Responses of auditory neurons to complex stimuli were recorded in the dorsal belt region of the auditory cortex of two taxonomically unrelated bat species, Rhinolophus rouxi and Pteronotus parnellii parnellii, both showing Doppler shift compensation behaviour. As in P.p.parnellii (Suga et al., J. Neurophysiol., 49, 1573 - 1626, 1983), cortical neurons of R.rouxi show facilitated responses to pairs of pure tones or frequency modulations. Best frequencies for the two components lie near the first and second harmonic of the echolocation call but are in most cases not harmonically related. Neurons facilitated by pairs of pure tones show little dependence on the delay between the stimuli, whereas pairs of frequency modulations evoke best facilitated responses at distinct best delays between 1 and 10 ms. Facilitated neurons are found in distinct portions of the dorsal cortical belt region, with a segregation of facilitated neurons responding to pure tones and to frequency modulations. Non-facilitated neurons are found throughout the field. Neurons are topographically aligned with increasing best delays along a rostrocaudal axis. The best delays between 2 and 4 ms are largely overrepresented numerically, and occupy approximately 56% of the cortical area containing facilitated neurons. A functional interpretation of the large overrepresentation of best delays approximately 3 ms is proposed. Facilitated neurons are located almost entirely within layer V of the dorsal field.

Spectral and temporal gating mechanisms enhance the clutter rejection in the echolocating bat, Rhinolophus rouxi.

Doppler shift compensation behaviour in horseshoe bats, Rhinolophus rouxi, was used to test the interference of pure tones and narrow band noise with compensation performance. The distortions in Doppler shift compensation to sinusoidally frequency shifted echoes (modulation frequency: 0.1 Hz, maximum frequency shift: 3 kHz) consisted of a reduced compensation amplitude and/or a shift of the emitted frequency to lower frequencies (Fig 2). Pure tones at frequencies between 200 and 900 Hz above the bat's resting frequency (RF) disturbed the Doppler shift compensation, with a maximum of interference between 400 and 550 Hz (Fig. 1). Minimum duration of pure tones for interference was 20 ms and durations above 40 ms were most effective (Fig. 3). Interfering pure tones arriving later than about 10 ms after the onset of the echolocation call showed markedly reduced interference (Fig. 4). Doppler shift compensation was affected by pure tones at the optimum interfering frequency with sound pressure levels down to -48 dB rel the intensity level of the emitted call (Fig. 5, 6). Narrow bandwidth noise (bandwidth from +/- 100 Hz to +/- 800 Hz) disturbed Doppler shift compensation at carrier frequencies between -250 Hz below and 800 Hz above RF with a maximum of interference between 250 and 500 Hz above resting frequency (Fig. 7). The duration and delay of the noise had similar influences on interference with Doppler shift compensation as did pure tones (Fig. 8, 9). Intensity dependence for noise interference was more variable than for pure tones (-32 dB to -45 dB rel emitted sound pressure level Fig. 10).(ABSTRACT TRUNCATED AT 250 WORDS)

An open, modular, distributed and redundant computer system for hospitals.

Based on his experience at the University of Würzburg in Germany, Dr. Schuller shows how a successful MUMPS-based hospital information system can be developed, including goals and requirements, networking, software hierarchies, programming in MUMPS, medical applications, data security/privacy and international standards.

Neural control of vocalization in bats: mapping of brainstem areas with electrical microstimulation eliciting species-specific echolocation calls in the rufous horseshoe bat.

1. The functional role of brainstem structures in the emission of echolocation calls was investigated in the rufous horseshoe bat. Rhinolophus rouxi, with electrical low-current microstimulation procedures. 2. Vocalizations without temporal and/or spectral distortions could be consistently elicited at low threshold currents (typically below 10 microA) within three clearly circumscribed brainstem areas, namely, the deep layers and ventral parts of the intermediate layers of the superior colliculus (SC), the deep mesencephalic nucleus (NMP) in the dorsal and lateral midbrain reticular formation and in a distinct area medial to the rostral parts of the dorsal nucleus of the lateral lemniscus. The mean latencies in the three vocal areas between the start of the electrical stimulus and the elicited vocalizations were 47 msec, 38 msec and 31 msec, respectively. 3. In pontine regions and the cuneiform nucleus adjacent to these three vocal areas, thresholds for eliciting vocalizations were also low, but the vocalizations showed temporal and/or spectral distortions and were often accompanied or followed by arousal of the animal. 4. Stimulus intensity systematically influenced vocalization parameters at only a few brain sites. In the caudo-ventral portions of the deep superior colliculus the sound pressure level of the vocalizations systematically increased with stimulus intensity. Bursts of multiple vocalizations were induced at locations ventral to the rostral parts of the cuneiform nucleus. No stimulus-intensity dependent frequency changes of the emitted vocalizations were observed. 5. The respiratory cycle was synchronized to the electrical stimuli in all regions where vocalizations could be elicited as well as in more ventrally and medially adjacent areas not yielding vocalizations on stimulation. 6. The possible functional involvement of the "vocal" structures in the audio-vocal feedback system of the Dopplercompensating horseshoe bat is discussed.