Allocentric or craniocentric representation of acoustic space: an electrotomography study using mismatch negativity

The world around us appears stable in spite of our constantly moving head, eyes, and body. How this is achieved by our brain is hardly understood and even less so in the auditory domain. Using electroencephalography and the so-called mismatch negativity, we investigated whether auditory space is encoded in an allocentric (referenced to the environment) or craniocentric representation (referenced to the head). Fourteen subjects were presented with noise bursts from loudspeakers in an anechoic environment. Occasionally, subjects were cued to rotate their heads and a deviant sound burst occurred, that deviated from the preceding standard stimulus either in terms of an allocentric or craniocentric frame of reference. We observed a significant mismatch negativity, i.e., a more negative response to deviants with reference to standard stimuli from about 136 to 188 ms after stimulus onset in the craniocentric deviant condition only. Distributed source modeling with sLORETA revealed an involvement of lateral superior temporal gyrus and inferior parietal lobule in the underlying neural processes. These findings suggested a craniocentric, rather than allocentric, representation of auditory space at the level of the mismatch negativity.     

Impaired mismatch negativity (MMN) generation in schizophrenia as a function of stimulus deviance,probability, and interstimulus/interdeviant interval

Schizophrenia is a severe mental disorder associated with disturbances in perception and cognition. Event-related potentials (ERP) provide a mechanism for evaluating potential mechanisms underlying neurophysiological dysfunction in schizophrenia. Mismatch negativity (MMN) is a short-duration auditory cognitive ERP component that indexes operation of the auditory sensory (`echoic') memory system. Prior studies have demonstrated impaired MMN generation in schizophrenia along with deficits in auditory sensory memory performance. MMN is elicited in an auditory oddball paradigm in which a sequence of repetitive standard tones is interrupted infrequently by a physically deviant (`oddball') stimulus. The present study evaluates MMN generation as a function of deviant stimulus probability, interstimulus interval, interdeviant interval and the degree of pitch separation between the standard and deviant stimuli. The major findings of the present study are first, that MMN amplitude is decreased in schizophrenia across a broad range of stimulus conditions, and second, that the degree of deficit in schizophrenia is largest under conditions when MMN is normally largest. The pattern of deficit observed in schizophrenia differs from the pattern observed in other conditions associated with MMN dysfunction, including Alzheimer's disease, stroke, and alcohol intoxication.     

Preattentive extraction of abstract auditory rules in speech sound stream: a mismatch negativity study using lexical tones

Background

Extraction of linguistically relevant auditory features is critical for speech comprehension in complex auditory environments, in which the relationships between acoustic stimuli are often abstract and constant while the stimuli per se are varying. These relationships are referred to as the abstract auditory rule in speech and have been investigated for their underlying neural mechanisms at an attentive stage. However, the issue of whether or not there is a sensory intelligence that enables one to automatically encode abstract auditory rules in speech at a preattentive stage has not yet been thoroughly addressed.

Methodology/Principal Findings

We chose Chinese lexical tones for the current study because they help to define word meaning and hence facilitate the fabrication of an abstract auditory rule in a speech sound stream. We continuously presented native Chinese speakers with Chinese vowels differing in formant, intensity, and level of pitch to construct a complex and varying auditory stream. In this stream, most of the sounds shared flat lexical tones to form an embedded abstract auditory rule. Occasionally the rule was randomly violated by those with a rising or falling lexical tone. The results showed that the violation of the abstract auditory rule of lexical tones evoked a robust preattentive auditory response, as revealed by whole-head electrical recordings of the mismatch negativity (MMN), though none of the subjects acquired explicit knowledge of the rule or became aware of the violation.

Conclusions/Significance

Our results demonstrate that there is an auditory sensory intelligence in the perception of Chinese lexical tones. The existence of this intelligence suggests that the humans can automatically extract abstract auditory rules in speech at a preattentive stage to ensure speech communication in complex and noisy auditory environments without drawing on conscious resources.     

Preattentive auditory information processing under exposure to the 902 MHz GSM mobile phone electromagnetic field: A mismatch negativity (MMN) study

Previous studies on the effects of the mobile phone electromagnetic field (EMF) on various event‐related potential (ERP) components have yielded inconsistent and even contradictory results, and often failed in replication. The mismatch negativity (MMN) is an auditory ERP component elicited by infrequent (deviant) stimuli differing in some physical features from the repetitive frequent (standard) stimuli in a sound sequence. The MMN provides a sensitive measure for cortical auditory stimulus feature discrimination, regardless of attention and other contaminating factors. In this study, MMN responses to duration, intensity, frequency, and gap changes were recorded in healthy young adults (n = 17), using a multifeature paradigm including several types of auditory change in the same stimulus sequence, while a GSM mobile phone was placed on either ear with the EMF (902 MHz pulsed at 217 Hz; SAR_1g = 1.14 W/kg, SAR_10g = 0.82 W/kg, peak value = 1.21 W/kg, measured with an SAM phantom) on or off. An MMN was elicited by all deviant types, while its amplitude and latency showed no significant differences due to EMF exposure for any deviant types. In the present study, we found no conclusive evidence that acute exposure to GSM mobile phone EMF affects cortical auditory change detection processing reflected by the MMN. Bioelectromagnetics 30:241–248, 2009. © 2009 Wiley‐Liss, Inc.     

BIAZA statistics guidelines: toward a common application of statistical tests for zoo research

Zoo research presents many statistical challenges, mostly arising from the need to work with small sample sizes. Efforts to overcome these often lead to the misuse of statistics including pseudoreplication, inappropriate pooling, assumption violation or excessive Type II errors because of using tests with low power to avoid assumption violation. To tackle these issues and make some general statistical recommendations for zoo researchers, the Research Group of the British and Irish Association of Zoos and Aquariums (BIAZA) conducted a workshop. Participants included zoo‐based researchers, university academics with zoo interests and three statistical experts. The result was a BIAZA publication Zoo Research Guidelines: Statistics for Typical Zoo Datasets (Plowman [ 2006 ] Zoo research guidelines: statistics for zoo datasets. London: BIAZA), which provides advice for zoo researchers on study design and analysis to ensure appropriate and rigorous use of statistics. The main recommendations are: (1) that many typical zoo investigations should be conducted as single case/small N randomized designs, analyzed with randomization tests, (2) that when comparing complete time budgets across conditions in behavioral studies, G tests and their derivatives are the most appropriate statistical tests and (3) that in studies involving multiple dependent and independent variables there are usually no satisfactory alternatives to traditional parametric tests and, despite some assumption violations, it is better to use these tests with careful interpretation, than to lose information through not testing at all. The BIAZA guidelines were recommended by American Association of Zoos and Aquariums (AZA) researchers at the AZA Annual Conference in Tampa, FL, September 2006, and are free to download from www.biaza.org.uk . Zoo Biol 27:226–233, 2008. © 2008 Wiley‐Liss, Inc.     

A new multitest correction (SGoF) that increases its statistical power when increasing the number of tests

Background  

The detection of true significant cases under multiple testing is becoming a fundamental issue when analyzing high-dimensional biological data. Unfortunately, known multitest adjustments reduce their statistical power as the number of tests increase. We propose a new multitest adjustment, based on a sequential goodness of fit metatest (SGoF), which increases its statistical power with the number of tests. The method is compared with Bonferroni and FDR-based alternatives by simulating a multitest context via two different kinds of tests: 1) one-sample t-test, and 2) homogeneity G-test.     

Head kinematics in mini-sled tests of foam padding: relevance of linear responses from free motion headform (FMH) testing to head angular responses

The revised Federal Motor Vehicle Safety Standard (FMVSS) No. 201 specifies that the safety performance of vehicle upper interiors is determined from the resultant linear acceleration response of a free motion headform (FMH) impacting the interior at 6.7 m/s. This study addresses whether linear output data from the FMH test can be used to select an upper interior padding that decreases the likelihood of rotationally induced brain injuries. Using an experimental setup consisting of a Hybrid III head-neck structure mounted on a mini-sled platform, sagittal plane linear and angular head accelerations were measured in frontal head impacts into foam samples of various stiffness and density with a constant thickness (51 mm) at low (approximately 5.0 m/s), intermediate (approximately 7.0 m/s), and high (approximately 9.6 m/s) impact speeds. Provided that the foam samples did not bottom out, recorded peak values of angular acceleration and change in angular velocity increased approximately linearly with increasing peak resultant linear acceleration and value of the Head Injury Criterion (HIC36). The results indicate that the padding that produces the lowest possible peak angular acceleration and peak change in angular velocity without causing high peak forces is the one that produces the lowest possible HIC36 without bottoming out in the FMH test.     

Brain evoked responses, a bioassay for central actions of adrenocorticotropin (ACTH 1-39) and corticotropin releasing hormone (CRH) in humans.

Blood borne hormones of the hypothalamus-pituitary-adrenal (HPA) axis form an afferent humoral system modulating a great variety of brain functions. In humans, bioassays consistently reflecting central nervous system actions have not been developed, so far. The present experiments are part of a series of studies which have been conducted to demonstrate the afferent influences of ACTH and CRH on brain activity by recording of auditory event-related brain potentials (ERPs) in healthy human subjects. In a double-blind within-subject comparison in 12 healthy male students, influences of 4 U ACTH and 100 micrograms CRH (infused within 2 h; the infusion starting 1 h prior to ERP recordings) were compared with the effects of a placebo infusion. Influences of the hormones were tested for the early, brain stem generated ERP components (BAEPs) and for the late components of the ERP associated with cortical stimulus processing. ACTH and CRH showed no consistent effect on BAEPs. ACTH, but not CRH, significantly reduced amplitudes of late ERP components, in particular, the Nd and P3 components which are considered signs of selective attention. These results are consistent with findings from previous studies demonstrating impaired ERP signs of selective attention in humans after administration of the 4-10 fragment of ACTH which lacks the peripheral adrenocorticotropic activity. Together with these foregoing studies, results from the present experiments further establish ERP methodology as a sensitive bioassay for CNS actions of hormones in humans.     

Motor program coding representation from a handwriting generator model: The production of line responses

In this paper, a model is employed that describes handwriting behaviors activated by curvilinear and angular velocity generators postulated to initiate and regulate pen tip velocity profiles. This model accounts for the observed differences between straight and curved line production and the effect of movement precues on these responses. Of particular interest is the observed interaction between precue information and line execution type for reaction time. It is shown that differences in reaction time can be explained by the model as a function of the number of parameters that need to be specified. Moreover, there is some evidence that the biomechanical system reacts in a privileged manner to command pulses for specific directions, and that the central nervous system attempts to compensate for these asymmetries. These data are some of the first to show that the benefits of precue extend beyond reaction time and that movement execution characteristics are influenced by motor preparation.     

d(GATC) sequences influence Escherichia coli mismatch repair in a distance-dependent manner from positions both upstream and downstream of the mismatch

The role of d(GATC) sites in determining the efficiency of methyl-directed mismatch repair in Escherichia coli was investigated. Transfection of host bacteria, both proficient and deficient in mismatch repair, with a series of artificially constructed M13 heteroduplexes showed that a decrease in the total number of d(GATC) sequences within these vectors lowered the efficiency of repair in vivo. Single hemimethylated d(GATC) sequences were still able to direct the correction event to the unmethylated strand, providing that the mismatch to d(GATC) site distance was shorter than approximately 1 kb. In excess of this distance, the effect of hemimethylated d(GATC) sites on mismatch correction was almost unnoticeable. The directionality of the repair event could be dictated by d(GATC) sequences situated both upstream and downstream of the mispair, suggesting that this important antimutagenic pathway can proceed bidirectionally.     

Mismatch negativity (MMN) for sequences of auditory and visual stimuli: evidence for a mechanism specific to the auditory modality

ERPs to sequences of standard and deviant sinusoidal 100 msec tone pips, high-contrast sinusoidal gratings and to their simultaneously presented combinations were recorded. Mismatch negativity (MMN), an ERP component elicited by deviant stimuli, was estimated for the different stimulus sequences in order to find out whether it reflects modality-specific processes or non-specific attentive phenomena. In addition to the auditory modality, we studied whether the mismatch response could be evoked by a deviant visual stimulus in a visual sequence or by a deviant stimulus in either modality. The results show that only auditory stimuli produced the mismatch response, suggesting that MMN is not a manifestation of a general attentional mechanism but is probably specific to the auditory modality.     

松墨天牛成虫对幼虫虫粪挥发性物质的触角电位反应及林间驱避试验

为了研制松墨天牛Monochamus alternatus Hope驱避剂,本文利用触角电位技术和田间试验的方法研究了松墨天牛雌雄成虫对幼虫虫粪挥发性物质的触角电位反应及幼虫虫粪己烷提取物、合成化合物混合物的林间驱避作用。结果表明：α-蒎烯、β-蒎烯、3-蒈烯、柠檬烯和长叶烯均能引起松墨天牛雌雄成虫一定的触角电生理反应,而4-甲基-2,6-二叔丁基苯酚不能引起松墨天牛雌雄成虫的触角电生理反应。林间驱避试验结果说明,幼虫虫粪的己烷提取物处理过的树干上的刻槽数明显少于对照树干上的刻槽数,二者具有极显著差异;有合成化合物的混合物存在的诱捕器诱捕到的雌虫数（平均值3.80±1.02）与对照诱捕到的雌虫数（平均值16.80±1.16）差异极显著。结果显示α-蒎烯、β-蒎烯、3-蒈烯、柠檬烯、长叶烯和4-甲基-2,6-二叔丁基苯酚的混合物对松墨天牛雌虫具有驱避作用,有望开发出一类新的驱避剂。     

Biological activity of ethyl (e,z)-2,4-decadienoate on different tortricid species: electrophysiological responses and field tests

Ethyl (E,Z)-2,4-decadienoate (pear ester) is known to be a kairomonal attractant for both male and female codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae). Electroantennographic (EAG) studies were conducted to investigate the sensitivities of codling moth, the chestnut torticid species Cydia fagiglandana (Zeller), Cydia splendana (Hübner), and Pammene fasciana L., and the green budmoth Hedya nubiferana Haworth to pear ester. The attractiveness of this compound to the different species was tested in several field-trapping experiments conducted in Italy. The EAG responses of the different tortricids species were dose-dependent. The field-trapping experiments confirmed the attractiveness of the compound to codling moth; similar activity was also shown on the chestnut tortricids in their respective host plant environment.     

Pedobarographic statistical parametric mapping (pSPM): a pixel-level approach to foot pressure image analysis

Traditional pedobarographic analyses conduct statistical tests on single pressure values extracted from discrete anatomical regions, a process which yields a low-resolution view of the continuous foot-ground interaction and which can involve substantial user interaction for region definition. Using image processing techniques derived from a cerebral imaging methodology called 'statistical parametric mapping' (SPM), we describe a fully automatic method that requires no anatomical assumptions or region definitions and that generates high-resolution continuous statistical maps across the entire plantar foot surface. Here, we demonstrate both pedobarographic SPM (pSPM) and its robustness to arbitrary foot postures by producing statistical maps for a sample of nine healthy young adults walking: normally, with everted feet, and with inverted feet. After spatially smoothing pedobarographic images, within-subjects (WS) and between-subjects (BS) registration were performed using an optimal rigid body transformation and an optimum affine transformation, respectively. Statistical tests were performed over all 742 foot pixels of the 270 registered images using a linear mass-univariate model and the resulting SPMs were compared qualitatively with results obtained using a traditional ten-region technique. SPMs were found to provide a qualitatively improved view of pedobarographic changes, but the more important finding was that regional pedobarographic statistics can misrepresent the trends of their constituent pixels and thus potentially lead to misinterpretations of foot function. Since pSPM is fully non-interactive, is robust to arbitrary foot posture, and provides rapid and easily interpretable results, it appears to be a suitable alternative to regionalization for routine pedobarographic analyses in both laboratory and clinic.     

Functional morphology of chonetidine (Brachiopoda) spines: biomechanical tests of a potential key innovation

Chonetidine brachiopods were a significant component of Paleozoic marine life; chonetidines experienced a major adaptive radiation during the Late Silurian and Early Devonian. The Chonetidina clade is united by the presence of spines on the hingeline but the function of these spines has not been clearly demonstrated. The present study performs a biomechanical experiment, using specimens of Neochonetes granulifera with and without artificial spines in a recirculating flume, to test if the spines may have inhibited entrainment in higher energy settings. Specimens with spines were less likely to be overturned or transported than those without spines, and were overturned or transported at significantly higher velocities than specimens without spines. Performance improved with the addition of another pair of spines. In addition, spinose specimens reoriented such that their commissures faced upstream. The results suggest that chonetidines could have survived in higher-energy environments, even if the brachiopods were not physically attached to the substrate. As such, it is functionally plausible that the evolution of hinge-spines may have possibly facilitated the adaptive radiation of the clade by enabling chonetidines to inhabit previously unoccupied habitats.