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At least 1,261 records · Page 70Linked to original sources
PubMed1976

Disproportionate tonotopic representation for processing CF-FM sonar signals in the mustache bat auditory cortex.

The extent of cortical representation of the peripheral sensory field depends on its importance for species behavior. The orientation sound of the mustache bat (Pteronotus parnellii rubiginosus) invariably consists of long constant-frequency and short frequency-modulated components and is indispensable for its survival. A disproportionately large part of the auditory cortex of this bat is occupied by neurons processing the predominant components in the orientation signal and Doppler-shifted echoes. This disproportionate cortical representation related to features of biologically significant signals is comparable to that in the somatosensory and visual systems in many mammals, but it has not previously been observed in the auditory system.

Action Potentials↗
PubMed2005

Phylogeography, population dynamics, and molecular evolution of European bat lyssaviruses.

European bat lyssaviruses types 1 and 2 (EBLV-1 and EBLV-2) are widespread in Europe, although little is known of their evolutionary history. We undertook a comprehensive sequence analysis to infer the selection pressures, rates of nucleotide substitution, age of genetic diversity, geographical origin, and population growth rates of EBLV-1. Our study encompassed data from 12 countries collected over a time span of 35 years and focused on the glycoprotein (G) and nucleoprotein (N) genes. We show that although the two subtypes of EBLV-1--EBLV-1a and EBLV-1b--have both grown at a low exponential rate since their introduction into Europe, they have differing population structures and dispersal patterns. Furthermore, there were strong constraints against amino acid change in both EBLV-1 and EBLV-2, as reflected in a low ratio of nonsynonymous to synonymous substitutions per site, particularly in EBLV-1b. Our inferred rate of nucleotide substitution in EBLV-1, approximately 5 x 10(-5) substitutions per site per year, was also one of the lowest recorded for RNA viruses and implied that the current genetic diversity in the virus arose 500 to 750 years ago. We propose that the slow evolution of EBLVs reflects their distinctive epidemiology in bats, where they occupy a relatively stable fitness peak.

Animals↗
PubMed2005

Identification of a novel coronavirus in bats.

Exotic wildlife can act as reservoirs of diseases that are endemic in the area or can be the source of new emerging diseases through interspecies transmission. The recent emergence of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) highlights the importance of virus surveillance in wild animals. Here, we report the identification of a novel bat coronavirus through surveillance of coronaviruses in wildlife. Analyses of the RNA sequence from the ORF1b and S-gene regions indicated that the virus is a group 1 coronavirus. The virus was detected in fecal and respiratory samples from three bat species (Miniopterus spp.). In particular, 63% (12 of 19) of fecal samples from Miniopterus pusillus were positive for the virus. These findings suggest that this virus might be commonly circulating in M. pusillus in Hong Kong.

Amino Acid Sequence↗
PubMed1994

'Bats below the bridge': is a potentially treatable neurovascular disorder being underdiagnosed in accident and emergency departments?

Basilar artery thrombosis (BATS) is a progressive disorder which may present with fluctuating neurological signs of varying degrees of severity. Unless the diagnosis is considered, the confused young patient may be thought to be under the influence of drugs or to be psychologically ill, and indeed the Munchausen syndrome may be considered. The more elderly patient may be diagnosed simply as having had a cerebrovascular accident. This paper presents the cases of three patients admitted through the accident and emergency (A&E) department of St Mary's Hospital, London with basilar artery thrombosis during a 6-month period. All these patients demonstrated the classic triad for this syndrome of: (1) long tract neurological signs, (2) impaired conscious level, and (3) complex ocular signs. The concern is that, for patients with more subtle signs, a diagnosis of BATS may not be considered, and a neurological opinion may be thus delayed and no treatment with anticoagulants or thrombolytic agents would be given. Two of the three patients were treated with anticoagulants and improved, while in the third patients anticoagulation was judged inappropriate and the patients died from progression of the disease with respiratory complications.

Aged↗
PubMed1979

Microvascular myogenic reaction in the wing of the intact unanesthetized bat.

Microvascular dimension and flow responses to stepwise changes in arterial and venous pressures, ranging from zero to +100 mmHg and zero to -75 mmHg have been recorded. Observations were made in arterioles, terminal arterioles, and precapillary sphincters in the wing web of intact, unanesthetized bats. The results show for all categories of vessels that with reduced transmural pressures there is a progressive increase in mean diameter and a decrease in rhythmic vasomotion rate. Flow changes are variable. For elevated transmural pressures there is a vasoconstriction with drastic flow reduction that is inconsistent with metabolic control. However, after prolonged elevation of pressure there is a progressive increase in flow, suggesting a "metabolic escape". Computed wall tension remains reasonably constant for a wide range of transmural pressures, suggesting that wall tension may be the controlled variable. These findings support the hypothesis of a myogenic reaction as a mechanism for maintenance of basal vascular tone in the intact unanesthetized bat.

Animals↗
PubMed1992

Modulation of bat wing venule contraction by transmural pressure changes.

We tested the hypothesis that the frequency and amplitude of spontaneous venular contractions in the bat wing could be modulated by changes in transmural pressure. In one series of experiments, venous pressure in the wing was elevated by pressurizing a box containing the body of the animal while the wing was exposed to atmospheric pressure. During this time, venular diameters were continuously recorded using intravital microscopic techniques while venular pressures were measured through servo-null micropipettes. In another series of experiments, single venular segments were dissected from the wing, cannulated, and pressurized in vitro. The results from both experimental protocols were qualitatively similar; alterations in venous pressure over a narrow range (+/- 5 cmH2O from control) produced substantial changes in contraction frequency and amplitude. The product of frequency and cross-sectional area was maximal over the venous pressure range between 10 and 15 cmH2O. Venules demonstrated a rate-sensitive component in their reaction to rapid pressure changes, because contraction bursts occurred immediately after positive pressure steps and quiescent periods often occurred after negative pressure steps. We conclude that venular vasomotion in the bat wing is modulated by intraluminal pressure and involves a bidirectional, rate-sensitive mechanism. In addition, comparisons with arteriolar vasomotion studies suggest that venules are more sensitive to luminal pressure changes than arterioles.

Animals↗
PubMed1982

Muscle enzyme profile, diet, and flight in South American bats.

Activities of four catabolic enzymes (citrate synthase, hexokinase, 3-hydroxyacyl-CoA dehydrogenase, and phosphorylase) were measured in the pectoralis muscles of 10 species of South American bats, representing four families. The pattern of enzyme activities in these tissues suggests that these muscles differ qualitatively with other mammalian and avian muscles in two respects. First, the muscles of all 10 bat species were much more highly oriented toward fat metabolism and away from glucose metabolism than in any previously measured skeletal muscle. Second, the species were divided into two major groups with respect to hexokinase activity. Primarily frugivorous species had hexokinase activities about 2-3 times as high as insectivorous species. It is suggested that the weight restrictions of flight limit glycogen storage and thus bias muscle metabolism toward fat. However, the extent to which pectoralis muscles have the capacity for glucose oxidation appears to be dependent on the intake of dietary glucose.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1994

Hyperosmolality and sperm storage in hibernating bats: prolongation of sperm life by dehydration.

Osmolalities of epididymal fluids obtained by micropuncture from hibernating species of bats (Myotis lucifugus) rise during sperm storage periods to as high as 1,523 mmol/kgH2O (approximately 5 times that of plasma). In vitro studies establish that hyperosmolality can preserve viability and prevent initiation of progressive motility in bat epididymal spermatozoa as well as induce their quiescence by reducing respiration. Reduction of osmolality (to 500-600 mmol/kgH2O) induces swelling of sperm and allows the initiation of motility and increased metabolic rate; further reduction of osmolality to < 300 mmol/kgH2O compromises permeability barriers and causes loss of motility. We hypothesize that seasonal establishment of hyperosmotic conditions driven by those cells that constitute the limits of the epididymal lumen dehydrates the compliant spermatozoa and thereby minimizes their metabolic needs. A novel form of cell storage dependent on unique adaptations of the epididymal epithelium for solute and water transport is implicated. To date, the operative osmolyte or osmolytes responsible for elevating osmolality in this system remain elusive.

Animals↗
PubMed1996

Dissociation of hypothalamic NPY from BAT uncoupling protein mRNA in rats exposed to 24 h thermoneutrality.

Neuropeptide Y (NPY) is increasingly considered to be involved in the central regulation of energy balance. Our previous studies suggest that hypothalamic NPY neurons of the arcuatoparaventricular (ARC-PVN) projection are inhibited in association with the marked increases in brown adipose tissue (BAT) thermogenesis and uncoupling protein (UCP) gene expression in rats exposed to cold. We therefore hypothesized that the NPYergic ARC-PVN system would be activated in a thermoneutral environment, when energy expenditure falls to a minimum, and that this activation could mediate the fall in BAT activity. We measured regional hypothalamic NPY concentrations, hypothalamic NPY receptor binding, and NPY mRNA together with UCP mRNA levels in rats exposed to thermoneutrality (29 degrees C) for 24 h. At thermoneutrality, UCP mRNA levels fell to 42% of those in controls maintained at 22 degrees C, but there were no significant changes in hypothalamic NPY or NPY mRNA levels or in NPY receptor binding. We conclude that the fall in UCP mRNA expression occurring under short-term thermoneutral condition is mediated by neuroendocrine mechanisms other than increased activity of hypothalamic NPY neurons.

Adipose Tissue, Brown↗
PubMed2006

Neural mechanisms underlying selectivity for the rate and direction of frequency-modulated sweeps in the inferior colliculus of the pallid bat.

This study describes mechanisms that underlie neuronal selectivity for the direction and rate of frequency-modulated sweeps in the central nucleus of the inferior colliculus (ICC) of the pallid bat (Antrozous pallidus). This ICC contains a high percentage of neurons (66%) that respond selectively to the downward sweep direction of the bat's echolocation pulse. Some (19%) are specialists that respond only to downward sweeps. Most neurons (83%) are also tuned to sweep rates. A two-tone inhibition paradigm was used to describe inhibitory mechanisms that shape selectivity for sweep direction and rate. Two different mechanisms can create similar rate tuning. The first is an early on-best frequency inhibition that shapes duration tuning, which in turn determines rate tuning. In most neurons that are not duration tuned, a delayed high-frequency inhibition creates rate tuning. These neurons respond to fast sweep rates, but are inhibited as rate slows, and delayed inhibition overlaps excitation. In these neurons, starting a downward sweep within the excitatory tuning curve eliminates rate tuning. However, if rate tuning is shaped by duration tuning, this manipulation has no effect. Selectivity for the downward sweep direction is created by an early low-frequency inhibition that prevents responses to upward sweeps. In addition to this asymmetry in arrival times of low- and high-frequency inhibitions, the bandwidth of the low-frequency sideband was broader. Bandwidth influences the arrival time of inhibition during an FM sweep because a broader sideband will be encountered sooner. These findings show that similar spectrotemporal filters can be created by different mechanisms.

Acoustic Stimulation↗
PubMed2003

Postnatal development of cochlear function in the mustached bat, Pteronotus parnellii.

Postnatal development of the mustached bat's cochlea was studied by measuring cochlear microphonic and compound action potentials. In adults, a cochlear resonance is involved in enhanced tuning to the second harmonic constant frequency component (CF2) of their echolocation calls at approximately 61 kHz This resonance is present immediately after birth in bats that do not yet echolocate. Its frequency is lower (46 kHz) and the corresponding threshold minimum of cochlear microphonic potentials is broader than in adults. Long-lasting ringing of the cochlear microphonic potential after tone stimulus offset that characterizes the adult auditory response close to CF2 is absent in newborns. In the course of the first 5 postnatal weeks, there is a concomitant upward shift of CF2 and the frequency of cochlear threshold minima. Up to the end of the third postnatal week, sensitivity of auditory threshold minima and the Q value of the cochlear resonance increase at a fast rate. Between 2 and 4 wk of age, two cochlear microphonic threshold minima are found consistently in the CF2 range that differ in their level-dependent dynamic growth behavior and are 1.5-5.7 kHz apart from each other. In older animals, there is a single minimum that approaches adult tuning in its sharpness. The data provide evidence to show that during maturation of the cochlea, the frequency and the sensitivity of the threshold minimum associated with CF2 increases and that these increases are associated with the fusion of two resonances that are partly dissociated in developing animals.

Acoustic Stimulation↗
PubMed2002

Functional organization of the pallid bat auditory cortex: emphasis on binaural organization.

This report maps the organization of the primary auditory cortex of the pallid bat in terms of frequency tuning, selectivity for behaviorally relevant sounds, and interaural intensity difference (IID) sensitivity. The pallid bat is unusual in that it localizes terrestrial prey by passively listening to prey-generated noise transients (1-20 kHz), while reserving high-frequency (<30 kHz) echolocation for obstacle avoidance. The functional organization of its auditory cortex reflects the need for specializations in echolocation and passive sound localization. Best frequencies were arranged tonotopically with a general increase in the caudolateral to rostromedial direction. Frequencies between 24 and 32 kHz were under-represented, resulting in hypertrophy of frequencies relevant for prey localization and echolocation. Most neurons (83%) tuned <30 kHz responded preferentially to broadband or band-pass noise over single tones. Most neurons (62%) tuned >30 kHz responded selectively or exclusively to the 60- to 30-kHz downward frequency-modulated (FM) sweep used for echolocation. Within the low-frequency region, neurons were placed in two groups that occurred in two separate clusters: those selective for low- or high-frequency band-pass noise and suppressed by broadband noise, and neurons that showed no preference for band-pass noise over broadband noise. Neurons were organized in homogeneous clusters with respect to their binaural response properties. The distribution of binaural properties differed in the noise- and FM sweep-preferring regions, suggesting task-dependent differences in binaural processing. The low-frequency region was dominated by a large cluster of binaurally inhibited neurons with a smaller cluster of neurons with mixed binaural interactions. The FM sweep-selective region was dominated by neurons with mixed binaural interactions or monaural neurons. Finally, this report describes a cortical substrate for systematic representation of a spatial cue, IIDs, in the low-frequency region. This substrate may underlie a population code for sound localization based on a systematic shift in the distribution of activity across the cortex with sound source location.

Animals↗
PubMed2006

Intracellular recording reveals temporal integration in inferior colliculus neurons of awake bats.

The central nucleus of the inferior colliculus (IC) is a major integrative center in the central auditory system. It receives information from both the ascending and descending auditory pathways. To determine how single IC neurons integrate information over a wide range of sound frequencies and sound levels, we examined their intracellular responses to frequency-modulated (FM) sounds in awake little brown bats (Myotis lucifugus). Postsynaptic potentials were recorded in response to downward FM sweeps of the range typical for little brown bats (80-20 kHz) and to three FM subcomponents (80-60, 60-40, and 40-20 kHz). The majority of recorded neurons responded to the 80- to 20-kHz downward FM sweep with a complex response. In this response an initial hyperpolarization was followed by depolarization with or without spike followed by hyperpolarization. Intracellular recordings in response to three FM subcomponents revealed that these neurons receive excitatory and inhibitory inputs from a wide range of sound frequencies. One third of IC neurons performed nearly linear temporal summation across a wide range of sound frequencies, whereas two thirds of IC neurons exhibited nonlinear summation with different degrees of nonlinearity. Some IC neurons showed different latencies of postsynaptic potentials in response to different FM subcomponents. Often responses to the later FM subcomponent occurred before responses to the earlier ones. This phenomenon may be responsible for response selectivity of IC neurons to FM sweeps.

Acoustic Stimulation↗
PubMed2004

Ambiguities in sound-duration selectivity by neurons in the inferior colliculus of the bat Molossus molossus from Cuba.

This study examines duration selectivity in auditory neurons of the inferior colliculus of the bat Molossus molossus (Molossidae, Chiroptera) from Cuba. Three main types of duration selectivity, short-, band-, and long-pass, as previously described in other species, are present in M. molossus. The range of best durations in the inferior colliculus of this species approximates the durations of their echolocation calls, suggesting that, as has been shown in other species of bats and frogs, the filter mechanism that produces duration tuning is selective for species-specific sounds relevant to behavior. Duration coding in M. molossus is not unambiguous because approximately 30% of the short- and band-pass neurons respond best to two different stimulus durations. This bimodal duration selectivity could be explained by time delayed excitatory inputs that coincide with an inhibitory rebound. In addition, the effect of stimulus intensity on duration selectivity was tested. For most of the neurons (78%), duration selectivity was affected by absolute sound pressure level and/or small changes of sound pressure. In this respect, the processing of stimulus duration by collicular neurons seems to be more complex in M. molossus than in other species studied so far.

Acoustic Stimulation↗
PubMed1985

Determinants of sound location selectivity in bat inferior colliculus: a combined dichotic and free-field stimulation study.

This study of the neural representation of sound location in the bat Pteronotus parnellii describes how the peripheral and central components of its auditory system shape the horizontal and vertical spatial selectivity of single neurons in the inferior colliculus. Pteronotus extracts spatial information from the echoes of an emitted pulse composed of four constant-frequency harmonics (30, 60, 90, and 120 kHz), each terminated by a downward frequency sweep. To quantify the intensity cues available in the echo, cochlear microphonic response thresholds were used to measure the directional selectivity of the ear and the interaural intensity level disparities (IIDs) created between ears at standardized speaker positions in the bat's frontal sound field, at frequencies in the pulse spectrum. Speaker positions where thresholds were lowest were termed the sensitive area (SA) of the ear. Positions where IID values were greater than 10 dB were termed the difference area (DA). Ear directionality exhibited a pronounced frequency dependence, both in terms of the degree of directional selectivity and the position of the SA. At the 30-kHz harmonic of the pulse, the ear was broadly directional; the SA covered most of the lower half of the ipsilateral field. The ear was highly directional at the 60- and 90-kHz harmonics. Also, the vertical position of the SA changed dramatically between 60 and 90 kHz, from the horizontal midline at 60 kHz to 40 degrees below the midline at 90 kHz. The positions of the DAs also showed a pronounced frequency dependence. The 30-kHz DA was restricted to the extreme lateral part of the frontal sound field. The 60- and 90-kHz DAs were located in the same positions as the equivalent SAs and exhibited the same difference in vertical position. The DAs of the pulse harmonics differ in both their horizontal and vertical positions; the ears thus generate pronounced binaural spectral cues, which provide two-dimensional spatial information. In the inferior colliculus, a combined paradigm of closed-field dichotic stimulation, followed by free-field stimulation, was used to document the frequency tuning and binaural response properties of single neurons and to correlate these properties with the neuron's horizontal and vertical spatial selectivity in the frontal sound field. Where a neuron responded to free-field stimulation at the lowest intensity is termed its SA. A neuron's frequency tuning primarily influenced its degree of spatial selectivity and its sensitivity in the vertical plane, reflecting the directional properties of the external ears at the neuron's best frequency.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Multiple time axes for representation of echo delays in the auditory cortex of the mustached bat.

The properties of the orientation sound (pulse) of the Jamaican mustached bat, Pteronotus parnellii parnellii is the same as the Panamanian mustached bat, P.p. rubiginosus. It consists of four harmonics, each containing a long constant-frequency (CF) component followed by a short frequency-modulated (FM) component. Thus, there are eight components in total: CF1-4 and FM1-4. The combination-sensitive area of the auditory cortex in P.p. parnellii consists of two major divisions (FM-FM and CF/CF areas) as in P.p. rubiginosus. The FM-FM area projects to the dorsal fringe (DF) and other areas. Response latencies of neurons in the DF area are longer than those in the FM-FM area. The distribution of latencies is unimodal for the FM-FM area, but bimodal for the DF area. In this electrophysiological study of the response properties of neurons in the DF and FM-FM areas, our aim was to find out how signal processing might be different between the two areas. Both the FM-FM and DF areas consist of three types of FM-FM combination-sensitive neurons: FM1-FM2, FM1-FM3, and FM1-FM4. They do not respond or respond poorly to pulse alone, echo alone, single CF tones or single FM sounds. But they show strong facilitation of response to the echo when it is delivered with particular delays from the pulse. The essential elements in the pulse-echo pair for facilitation are the FM1 of the pulse and FM2 or FM3 or FM4 of the echo. In both the FM-FM and DF areas, the great majority of neurons show short-lasting facilitation, and other neurons show long-lasting facilitation. FM-FM neurons are tuned to particular echo delays, i.e., target ranges. In both the FM-FM and DF areas, the width of a delay-tuning curve is linearly related to the value of a best delay. There is no sign that processing of range information is more specialized in the DF area than the FM-FM area. In both the FM-FM and DF areas, three types of FM-FM neurons form independent clusters. Along the major axis of each cluster, best delays for facilitative responses of neurons systematically change according to the loci of the neurons. The more posterior the location, the longer the best delay is. Therefore, there are six time (i.e., range) axes in total. The time axis in the DF area is shorter than that in the FM-FM area.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1988

Binaural neurons in the mustache bat's inferior colliculus. I. Responses of 60-kHz EI units to dichotic sound stimulation.

1. Single-unit responses to closed-field, dichotic sound stimuli were obtained from EI neurons in the mustache bat's inferior colliculus; these neurons are excited by sound to the contralateral ear and inhibited by sound to the ipsilateral ear. All units were tuned to the 60-kHz component of the bat's sonar signal. The goal of the study was to describe basic features of the sensitivity to interaural intensity differences (IIDs) and sound intensity among an isofrequency population of EI neurons. The following paper describes how these features of IID sensitivity shape the response to free-field sounds. 2. Three features of IID sensitivity were considered. The inhibitory threshold (Figs. 1 and 2) described the IID at which inhibitory effects became pronounced; it was defined as the IID at which the excitatory response to contralateral sound was suppressed by 50%. Most units (68%) were inhibited at positive IID values, for which the ipsilateral (inhibitory) sound was more intense. The maximum inhibition (Figs. 1 and 3) described the strength of ipsilateral inhibition; it was defined as the percent that each unit was inhibited below its response to monaural stimulation of the contralateral ear. The majority of units (58%) were almost totally suppressed by a sufficiently intense ipsilateral sound. The IID range (Figs. 1 and 4) described the sharpness or slope of the IID cutoff; it was defined as the IID range over which the response changed from nearly unsuppressed (80% of maximum response) to near maximum suppression (20% of maximum response). Most units (71%) had IID ranges of less than or equal to 15 dB. 3. A significant correlation between the inhibitory threshold and the maximum inhibition (Fig. 5) among the sample of EI units suggests that some common neural mechanisms underlie these features of IID sensitivity. 4. The response of EI neurons to binaural stimuli was a function of sound intensity as well as IID (Fig. 7). In part, this resulted from intensity-dependent changes in properties of binaural inhibition. For most units, basic measures of IID sensitivity changed to a limited extent as the sound intensity changed.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1988

Combination-sensitive neurons in the ventroanterior area of the auditory cortex of the mustached bat.

1. Because the ventroanterior (VA) area is one of the target areas of the FM-FM area in the auditory cortex of the mustached bat, Pteronotus parnellii parnellii, response properties of combination-sensitive neurons in this area were studied with constant-frequency (CF) tones, frequency-modulated (FM) sounds, and sounds similar to the bat's biosonar signal (pulse), which consisted of long CF components (CF1-4) and short FM components (FM1-4). CF1-4 and FM1-4 are the components in the four harmonics (H1-4) of the pulse. 2. Combination-sensitive neurons are clustered in a small area immediately anteroventral to the Doppler-shifted CF processing (DSCF) area and posteroventral to the anterior division of the primary auditory cortex. Because this cluster in the VA area is small, it was difficult to record a sufficient number of combination-sensitive neurons to explore the functional organization of the cluster, but it was found that the response properties of these VA neurons were unique. 3. Combination-sensitive neurons in the VA area are tuned to particular combinations of signal elements similar to the first and second harmonics of the pulse and/or echo. Unlike neurons in the FM-FM, dorsal fringe (DF), and CF/CF areas, no neurons in the VA area are tuned to the signal elements in the first and third or fourth harmonics. 4. The great majority of combination-sensitive neurons in the VA area can not be easily classified into either FM-FM or CF/CF neurons, because they show facilitative responses to combinations of CF1/CF2, FM1-FM2, and FM1-CF2. Therefore, they are called H1-H2 neurons. In the FM-FM and CF/CF areas, all the neurons could be easily classified as FM-FM or CF/CF. This uniqueness of H1-H2 neurons is related to the fact that their best frequencies for facilitation are predominantly between 61.0 and 62.0 kHz, i.e., within the frequency range of stabilized Doppler-shifted echo CF2. 5. In addition to 27 H1-H2 neurons, 7 FM1-FM2 neurons were also recorded in the VA area. The best delays of these H1-H2 and FM1-FM2 neurons measured with FM1-FM2 pairs are between 1 and 10 ms. Unlike neurons in the FM-FM and DF areas, their delay-tuning curves are very broad, even if their best delays are short, and extend beyond zero delay to several millisecond "negative" delays of the FM2 from the FM1, i.e., several millisecond delays of the FM1 from the FM2.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗