The detection of anisochrony in monaural and interaural sound sequences

Nakao and Axelrod (1976) and van Noorden (1975) showed that the threshold for discriminating an anisochronous duple rhythm (a series of clicks with a temporal offset on every other one) from an isochronous rhythm (no offset) is poorer when the clicks are presented alternately to the two ears than when they are presented to the same ears. Van Noorden reported that the difference between the thresholds in the alternating and nonalternating conditions varied with the tempo of the sequence. Nakao and Axelrod found invariance of this threshold difference with sequence speed. According to our quantification of temporal processing of interaural sequences, the latter result should be expected. We carried out five psychophysical experiments to establish interaural and monaural discrimination between isochronous and anisochronous rhythms. Across experiments, base time intervals of 60-720 msec were spanned. The main result was that we replicated the poorer discrimination for interaural sequences. This deterioration in discrimination was the same for all sequence speeds. It was also the case that the thresholds were almost constant up to a sound repetition rate of about 3 per second, but increased linearly with slower rates. This result supports evidence in the literature that temporal processing of sequences faster than about 3-4 sounds per second differs from temporal processing of slower sequences.     

Effects of ear plugging on single-unit azimuth sensitivity in cat primary auditory cortex. I. Evidence for monaural directional cues

1. Single-unit recordings were carried out in primary auditory cortex (AI) of barbiturate-anesthetized cats. Neurons, sensitive to sound direction in the horizontal plane (azimuth), were identified by their responses to noise bursts, presented in the free field, that varied in azimuth and sound pressure level (SPL). SPLs typically varied between 0 and 80 dB and were presented at each azimuth that was tested. Each azimuth-sensitive neuron responded well to some SPLs at certain azimuths and did not respond well to any SPL at other azimuths. This report describes AI neurons that were sensitive to the azimuth of monaurally presented noise bursts. 2. Unilateral ear plugging was used to test each azimuth-sensitive neuron's response to monaural stimulation. Ear plugs, produced by injecting a plastic ear mold compound into the concha and ear canal, attenuated sound reaching the tympanic membrane by 25-70 dB. Binaural interactions were inferred by comparing responses obtained under binaural (no plug) and monaural (ear plug) conditions. 3. Of the total sample of 131 azimuth-sensitive cells whose responses to ear plugging were studied, 27 were sensitive to the azimuth of monaurally presented noise bursts. We refer to these as monaural directional (MD) cells, and this report describes their properties. The remainder of the sample consisted of cells that either required binaural stimulation for azimuth sensitivity (63/131), because they were insensitive to azimuth under unilateral ear plug conditions or responded too unreliably to permit detailed conclusions regarding the effect of ear plugging (41/131). 4. Most (25/27) MD cells received either monaural input (MD-E0) or binaural excitatory/inhibitory input (MD-EI), as inferred from ear plugging. Two MD cells showed other characteristics. The contralateral ear was excitatory for 25/27 MD cells. 5. MD-E0 cells (22%, 6/27) were monaural. They were unaffected by unilateral ear plugging, showing that they received excitatory input from one ear, and that stimulation of the other ear was without apparent effect. On the other hand, some monaural cells in AI were insensitive to the azimuth of noise bursts, showing that sensitivity to monaural directional cues is not a property of all monaural cells in AI. 6. MD-EI cells (70%, 19/27) exhibited an increase in responsiveness on the side of the plugged ear, showing that they received excitatory drive from one ear and inhibitory drive from the other. MD-EI cells remained azimuth sensitive with the inhibitory ear plugged, showing that they were sensitive to monaural directional cues at the excitatory ear.(ABSTRACT TRUNCATED AT 400 WORDS)     

Lateralization of the startle reflex circuit in humans: An examination with monaural probes following unilateral temporal lobe resection.

Startle reflex (SR) modulation elicited by monaural probes during affective picture viewing was investigated in patients following left temporal lobectomy (LTL; n = 8) and right temporal lobectomy (RTL; n = 10) and in controls (n = 18). All patients had undergone anteromedial temporal lobe (ATL) resection. LTL participants exhibited attenuated overall SR magnitude. Affective SR modulation in controls was significant for left ear probes, at both eyes, but not for right ear probes. RTL but not LTL participants displayed significant startle attenuation during pleasant picture viewing. Results suggest that monaural startle probes primarily activate structures in the ipsilateral ATL and that the ATLs are interconnected, with the left ATL more critical in perceiving arousing properties of affective stimuli, necessary for affective SR modulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Syntactic and thematic processing in sentence comprehension: Evidence for a temporal dissociation.

The time courses for processing constituent structure relations, subcategorization restrictions, and thematic role relations during sentence comprehension were measured with reaction time and speed–accuracy trade-off variants of a grammaticality judgment task. Thematic role processing was found to be delayed by as much as 100 ms relative to the time when constituent structure and subcategorization information were processed. These data suggest a model of sentence comprehension in which the construction of a syntactic representation temporally leads the construction of a more embellished thematic representation. Serial and parallel variants of such a model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for separate pathways for color and luminance detection mechanisms

We measure threshold versus contrast (TvC) functions for chromatic (red-green) and luminance sine-wave-grating stimuli for (1) the detection of luminance in the presence of color contrast and (2) the detection of color in the presence of luminance contrast. We find that, although these crossed TvC functions both display a dipperlike shape, their facilitation differs from that found for standard uncrossed dipper functions (luminance on luminance or color on color contrast). Their facilitation disappears (cross condition 1) or is reduced (cross condition 2) by randomized presentation of the phase of the test and the mask, and the remaining facilitation (cross condition 2) displays no spatial tuning. We argue that these crossed facilitatory interactions cannot be explained by detection mechanisms with common inputs from color and luminance contrast (a nonindependence of transduction), and we present evidence that instead they reflect the use of local cues in the stimuli. We also measure the luminance-luminance TvC function in the presence of a fixed suprathreshold color contrast. The results demonstrate that, even when the color contrast produces a masking of the luminance thresholds, luminance-luminance facilitation still occurs. Thus the opposing effects of masking and facilitation can occur simultaneously. Furthermore, while luminance-luminance facilitation occurs independently of color contrast, masking can be produced by either contrast. This suggests that masking and facilitation have different underlying origins. Similar results are found for the color detection thresholds in the presence of a luminance pedestal. We conclude that there are separate pathways for the detection of color and luminance contrast, each with no input from the other contrast. We suggest that the cross masking reflects divisive interactions between these pathways that is restricted to high contrasts.     

Evidence for auditory temporal distinctiveness: Modality effects in order and frequency judgments.

Two new, long-lasting phenomena involving modality of stimulus presentation are documented. In one series of experiments we investigated effects of modality of presentation on order judgments. Order judgments for auditory words were more accurate than order judgments for visual words at both the beginning and the end of lists, and the auditory advantage increased with the temporal separation of the successive items. A second series of experiments investigated effects of modality on estimates of presentation frequency. Frequency estimates of repeated auditory words exceeded frequency estimates of repeated visual words. The auditory advantage increased with frequency of presentation, and this advantage was not affected by the retention interval. These various effects were taken as support for a temporal coding assumption, that auditory presentation produces a more accurate encoding of time of presentation than does visual presentation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

HCW轧机内辊缝闭环厚控系统的弯辊力补偿方法

分析了HCW轧机内辊缝闭环时弯辊力变化对带材厚度的影响 ;针对西南精密带钢厂HCW 6 5 0mm轧机的实际影响情况 ,回归了在线补偿数学模型。运行结果表明 ,提出的处理方法很好地解决了工作辊轴移和弯辊力变化对带材厚度的影响。     

Bridging the gap: Transitive associations between items presented in similar temporal contexts.

In episodic memory tasks, associations are formed between items presented close together in time. The temporal context model (TCM) hypothesizes that this contiguity effect is a consequence of shared temporal context rather than temporal proximity per se. Using double-function lists of paired associates (e.g., A–B, B–C) presented in a random order, the authors examined associations between items that were not presented close together in time but that were presented in similar temporal contexts. After learning, across-pair associations fell off with distance in the list, as if subjects had integrated the pairs into a coherent memory structure. Within-pair associations (e.g., A–B) were strongly asymmetric favoring forward transitions; across-pair associations (e.g., A–C) showed no evidence of asymmetry. While this pattern of results presented a stern challenge for a heteroassociative mediated chaining model, TCM provided an excellent fit to the data. These findings suggest that contiguity effects in episodic memory do not reflect direct associations between items but rather a process of binding, encoding, and retrieval of a gradually changing representation of temporal context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A gap detection tactility test for sensory deficits associated with carpal tunnel syndrome

An automated gap detection tactility test was investigated for quantifying sensory deficits associated with carpal tunnel syndrome (CTS). The test, which involved sensing a tiny gap in an otherwise smooth surface by probing with the finger, had functional resemblance to many work-related tactile activities such as detecting scratches or surface defects. Gap detection thresholds were measured using the converging staircase method of limits paradigm. Sixteen normal subjects between 21 and 66 years of age were tested for studying important factors affecting gap detection thresholds. Actively probing with the index finger had a threshold almost an order of magnitude more sensitive (mean = 0.19 mm, SD = 0.11 mm) than passive touch (mean = 1.63 mm, SD = 0.62 mm), which was similar to two-point discrimination. Average thresholds decreased by 24% as contact force increased from 25 to 75 g. Performance in this tactility test quickly stabilized and showed little learning effects over the period of the test, as evidenced by the lack of significant differences between six replicates. The results were highly repeatable. No significant threshold differences were observed between test and retest trials on different days, or between dominant and non-dominant hands. A contact force of 50 g was recommended as optimal for this test since it required moderate force but resulted in a smaller threshold compared with 25 or 75 g. A companion study was conducted using eight normal subjects and ten subjects diagnosed as having CTS. Average gap detection threshold, when finger probing was allowed, was 0.20 mm (SD = 0.11 min) for the normal subjects and increased two-fold to 0.40 mm (SD = 0.19 mm) for the CTS subjects. Average gap detection threshold, when the finger probing was not allowed, was 1.71 mm (SD = 0.53 mm) for the normal subjects and increased by 48% to 2.53 mm (SD = 0.87 mm) for the CTS subjects. The results suggest that people suffering from CTS may experience similar functional deficits in daily living and work activities. The small inter-subject variability makes this test a candidate for having utility as a monitoring test for loss of cutaneous tactile sensitivity.     

A novel process for mutation detection using uracil DNA-glycosylase

A novel process is presented for the detection of known mutations and polymorphisms in DNA. This process, termed glycosylase mediated polymorphism detection (GMPD) involves amplification of the target DNA using three normal dNTPs and a fourth modified dNTP, whose base is a substrate for a specific DNA-glycosylase once incorporated into the DNA. The work described here utilises uracil DNA-glycosylase as the specific glycosylase and dUTP as the modified dNTP. Primers are designed so that during extension, the position of the first uracil incorporated into the extended primers differs depending on whether a mutation is present or absent. Subsequent glycosylase excision of the uracil residues followed by cleavage of the apyrimidinic sites allows detection of the mutation in the amplified fragment as a fragment length polymorphism. Variation in the sizes of the fragment length polymorphisms generated, can be readily achieved through the use of inosine bases in place of adenine bases in the upper and/or lower primers. The GMPD process is also adaptable to solid phase analysis. The use of the process for detection of mutations in the RYR1 and CFTR genes is demonstrated. Overall, the simplicity, specificity, versatility and flexibility of the GMPD process make it an attractive candidate for both small and large scale application in mutation detection and genome analysis.     

Evidence for an efflux pump in multidrug-resistant Campylobacter jejuni

Mechanisms of drug resistance in Campylobacter jejuni were investigated. Mutant strains 34PEFr, which was resistant to pefloxacin (128-fold increase in the MIC), and 34CTXr, which was resistant to cefotaxime (32-fold increase in the MIC) and which was derived from the susceptible parent 34s, were obtained by serial passages on pefloxacin and cefotaxime gradient plates, respectively. Both mutants showed cross-resistance to erythromycin, chloramphenicol, tetracycline, beta-lactams, and quinolones. While the quinolone resistance of strain PEFr could be explained by a mutation at codon 86 of the gyrA gene, the multidrug resistance phenotype of both strains was further investigated. Accumulation of pefloxacin, ciprofloxacin, and minocycline was measured by fluorometry and was found to be lower in the mutant strains than in the parent strain. Preincubation of the cells with carbonyl cyanide m-chlorophenylhydrazone, however, completely abolished this difference. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane preparations from both mutant strains showed overexpression of two proteins of 55 and 39 kDa which were absent from the outer membranes of the wild-type strain. These results indicate that in C. jejuni 34PEFr and 34CTXr, multidrug resistance is associated with an efflux system with a broad specificity.     

Latent learning in medial temporal amnesia: Evidence for disrupted representational but preserved attentional processes.

Damage to the hippocampus and medial temporal (MT) structures can lead to anterograde amnesia and may also impair latent teaming, in which prior exposure to cues affects their subsequent associability. Normally, latent teaming may reflect both representational and attentional mechanisms. Prior work has suggested that individuals with NIT amnesia have specific deficits in representational processing; thus, latent teaming that invokes primarily representational mechanisms might be especially impaired in MT amnesia. The current results provide preliminary confirmation of this prediction. In Experiment 1, a latent teaming paradigm expected to invoke representational mechanisms was impaired in individuals with MT amnesia, whereas in Experiment 2, a paradigm expected to invoke other attentional mechanisms was spared in individuals with MT amnesia. This suggests the representational and attentional components of latent teaming are dissociable and differentially affected in anterograde amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural correlates of gap detection and auditory fusion in cat auditory cortex

Responses were recorded from 130 single neurones in the primary auditory cortex of 12 ketamine-anaesthetized cats in response to double-click stimuli, to a /ba/-/pa/ phoneme continuum and to gaps inserted early (after 5 ms) and late (after 500 ms) in a 1 s duration noiseburst. Stimulus levels were between 45 and 75 dB SPL. Neural detection threshold for the 'late gap' was less than 5 ms. For the double click and 'early gap' stimuli thresholds were between 40 and 50 ms, whereas the phoneme continuum threshold for voice-onset-time (VOT) was between 10 and 25 ms. The 'late gap' and VOT thresholds are similar to psychophysical gap detection and the /ba/-/pa/ categorical perception boundary respectively.     

Strategies for rare-event detection: an approach for automated fetal cell detection in maternal blood

This article explores the feasibility of the use of automated microscopy and image analysis to detect the presence of rare fetal nucleated red blood cells (NRBCs) circulating in maternal blood. The rationales for enrichment and for automated image analysis for "rare-event" detection are reviewed. We also describe the application of automated image analysis to 42 maternal blood samples, using a protocol consisting of one-step enrichment followed by immunocytochemical staining for fetal hemoglobin (HbF) and FISH for X- and Y-chromosomal sequences. Automated image analysis consisted of multimode microscopy and subsequent visual evaluation of image memories containing the selected objects. The FISH results were compared with the results of conventional karyotyping of the chorionic villi. By use of manual screening, 43% of the slides were found to be positive (>=1 NRBC), with a mean number of 11 NRBCs (range 1-40). By automated microscopy, 52% were positive, with on average 17 NRBCs (range 1-111). There was a good correlation between both manual and automated screening, but the NRBC yield from automated image analysis was found to be superior to that from manual screening (P=.0443), particularly when the NRBC count was >15. Seven (64%) of 11 XY fetuses were correctly diagnosed by FISH analysis of automatically detected cells, and all discrepancies were restricted to the lower cell-count range. We believe that automated microscopy and image analysis reduce the screening workload, are more sensitive than manual evaluation, and can be used to detect rare HbF-containing NRBCs in maternal blood.     

The temporal dynamics of visual search: Evidence for parallel processing in feature and conjunction searches.

Feature and conjunction searches have been argued to delineate parallel and serial operations in visual processing. The authors evaluated this claim by examining the temporal dynamics of the detection of features and conjunctions. The 1st experiment used a reaction time (RT) task to replicate standard mean RT patterns and to examine the shapes of the RT distributions. The 2nd experiment used the response-signal speed-accuracy trade-off (SAT) procedure to measure discrimination (asymptotic detection accuracy) and detection speed (processing dynamics). Set size affected discrimination in both feature and conjunction searches but affected detection speed only in the latter. Fits of models to the SAT data that included a serial component overpredicted the magnitude of the observed dynamics differences. The authors concluded that both features and conjunctions are detected in parallel. Implications for the role of attention in visual processing are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for an X-linked genetic component in familial typical migraine

Although in cord blood (CB) transplantation graft-versus-host disease (GVHD) is reported to be less severe, GVHD may occur even in patients with HLA-identical sibling donors. This result shows that HLA typing can not entirely predict GVHD. The standard MLR with CB cells was either normal or slightly reduced compared with adult peripheral blood (PB) cells. We used two manipulations to increase the responses of CB cells to allo-antigens. The first was to treat the stimulator cells with cytokines, and the second to amplify weak proliferative responses by adding exogenous cytokines to MLR cultures (modified MLR). The stimulator cells were treated with both interferon-gamma (IFN-gamma) and IL-4. The responder cells were treated with both IL-2 and tumour necrosis factor-alpha (TNF-alpha). It is still to be determined whether or not this cytokine-enhanced MLR could be a possible predictor of GVHD. However, using these cytokines, 90% of CB could recognize allo-antigens, even if the standard MLR was negative.