The transfer of social exclusion and inclusion functions through derived stimulus relations.

PubMed

Munnelly, Anita; Martin, Georgina; Dack, Charlotte; Zedginidze, Ann; McHugh, Louise

2014-09-01

Previous studies have found that social exclusion can cause distress to those excluded. One method used to study social exclusion is through a virtual ball-toss game known as Cyberball. In this game, participants may be excluded from or included in the ball-toss game and typically report lower feelings of self-esteem, control, belonging, and meaningful existence following exclusion. Experiments 1 and 2 sought to explore the transfer of feelings of exclusion and inclusion through stimulus equivalence classes. In both experiments, participants were trained to form two three-member equivalence classes (e.g., A1-B1, B1-C1; A2-B2, B2-C2) and were tested with novel stimulus combinations (A1-C1, C1-A1, A2-C2, C2-A2). Thereafter, participants were exposed to the Cyberball exclusion and inclusion games. In these games, one stimulus (C1) from one equivalence class was assigned as the Cyberball inclusion game name, whereas one stimulus (C2) from the other equivalence class was assigned as the Cyberball exclusion game name. In Experiment 2, participants were only exposed to the Cyberball exclusion game. During a subsequent transfer test, participants were asked to rate how included in or excluded from they thought they would be in other online games, corresponding to members of both equivalence classes. Participant reported that they felt they would be excluded from online games if the games were members of the same equivalence class as C2. In contrast, participants reported that they felt they would be included in online games if the games were members of the same equivalence class as C1. Results indicated the transfer of feelings of inclusion (Experiment 1) and feelings of exclusion (Experiments 1 and 2) through equivalence classes.

Controlling Relations in Baseline Conditional Discriminations as Determinants of Stimulus Equivalence

ERIC Educational Resources Information Center

de Rose, Julio C.; Hidalgo, Matheus; Vasconcellos, Mariliz

2013-01-01

Variation in baseline controlling relations is suggested as one of the factors determining variability in stimulus equivalence outcomes. This study used single- comparison trials attempting to control such controlling relations. Four children learned AB, BC, and CD conditional discriminations, with 2 samples and 2 comparison stimuli. In Condition…

Teaching Generatively: Learning about Disorders and Disabilities

ERIC Educational Resources Information Center

Alter, Margaret M.; Borrero, John C.

2015-01-01

Stimulus equivalence procedures have been used to teach course material in higher education in the laboratory and in the classroom. The current study was a systematic replication of Walker, Rehfeldt, and Ninness (2010), who used a stimulus equivalence procedure to train information pertaining to 12 disorders. Specifically, we conducted (a) a…

CPM Test-Retest Reliability: "Standard" vs "Single Test-Stimulus" Protocols.

PubMed

Granovsky, Yelena; Miller-Barmak, Adi; Goldstein, Oren; Sprecher, Elliot; Yarnitsky, David

2016-03-01

Assessment of pain inhibitory mechanisms using conditioned pain modulation (CPM) is relevant clinically in prediction of pain and analgesic efficacy. Our objective is to provide necessary estimates of intersession CPM reliability, to enable transformation of the CPM paradigm into a clinical tool. Two cohorts of young healthy subjects (N = 65) participated in two dual-session studies. In Study I, a Bath-Thermode CPM protocol was used, with hot water immersion and contact heat as conditioning- and test-stimuli, respectively, in a classical parallel CPM design introducing test-stimulus first, and then the conditioning- and repeated test-stimuli in parallel. Study II consisted of two CPM protocols: 1) Two-Thermodes, one for each of the stimuli, in the same parallel design as above, and 2) single test-stimulus (STS) protocol with a single administration of a contact heat test-stimulus, partially overlapped in time by a remote shorter contact heat as conditioning stimulus. Test-retest reliability was assessed within 3-7 days. The STS-CPM had superior reliability intraclass correlation (ICC 2 ,: 1  = 0.59) over Bath-Thermode (ICC 2 ,: 1  = 0.34) or Two-Thermodes (ICC 2 ,: 1  = 0.21) protocols. The hand immersion conditioning pain had higher reliability than thermode pain (ICC 2 ,: 1  = 0.76 vs ICC 2 ,: 1  = 0.16). Conditioned test-stimulus pain scores were of good (ICC 2 ,: 1  = 0.62) or fair (ICC 2 ,: 1  = 0.43) reliability for the Bath-Thermode and the STS, respectively, but not for the Two-Thermodes protocol (ICC 2 ,: 1  = 0.20). The newly developed STS-CPM paradigm was more reliable than other CPM protocols tested here, and should be further investigated for its clinical relevance. It appears that large contact size of the conditioning-stimulus and use of single rather than dual test-stimulus pain contribute to augmentation of CPM reliability. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Teaching generatively: Learning about disorders and disabilities.

PubMed

Alter, Margaret M; Borrero, John C

2015-01-01

Stimulus equivalence procedures have been used to teach course material in higher education in the laboratory and in the classroom. The current study was a systematic replication of Walker, Rehfeldt, and Ninness (2010), who used a stimulus equivalence procedure to train information pertaining to 12 disorders. Specifically, we conducted (a) a written posttest immediately after each training unit and (b) booster training sessions for poor performers. Results showed immediate improvement from pretest to posttest scores after training, but problems with maintenance were noted in the final examination. Implications of poor maintenance are discussed in the context of the current study and stimulus equivalence research in higher education generally. © Society for the Experimental Analysis of Behavior.

Using the Stimulus Equivalence Paradigm to Teach Course Material in an Undergraduate Rehabilitation Course

ERIC Educational Resources Information Center

Walker, Brooke D.; Rehfeldt, Ruth Anne; Ninness, Chris

2010-01-01

In 2 experiments, we examined whether the stimulus equivalence instructional paradigm could be used to teach relations among names, definitions, causes, and common treatments for disabilities using a selection-based intraverbal training format. Participants were pre- and posttested on vocal intraverbal relations and were trained using…

Electrophysiological Correlates of Stimulus Equivalence Processes

ERIC Educational Resources Information Center

Haimson, Barry; Wilkinson, Krista M.; Rosenquist, Celia; Ouimet, Carolyn; McIlvane, William J.

2009-01-01

Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g.,…

Establishing Auditory-Tactile-Visual Equivalence Classes in Children with Autism and Developmental Delays

ERIC Educational Resources Information Center

Mullen, Stuart; Dixon, Mark R.; Belisle, Jordan; Stanley, Caleb

2017-01-01

The current study sought to evaluate the efficacy of a stimulus equivalence training procedure in establishing auditory-tactile-visual stimulus classes with 2 children with autism and developmental delays. Participants were exposed to vocal-tactile (A-B) and tactile-picture (B-C) conditional discrimination training and were tested for the…

Preliminary Findings on the Effects of Self-Referring and Evaluative Stimuli on Stimulus Equivalence Class Formation

ERIC Educational Resources Information Center

Merwin, Rhonda M.; Wilson, Kelly G.

2005-01-01

Thirty-two subjects completed 2 stimulus equivalence tasks using a matching-to-sample paradigm. One task involved direct reinforcement of conditional discriminations designed to produce derived relations between self-referring stimuli (e.g., me, myself, I) and positive evaluation words (e.g., whole, desirable, perfect). The other task was designed…

Exploration of the psychophysics of a motion displacement hyperacuity stimulus.

PubMed

Verdon-Roe, Gay Mary; Westcott, Mark C; Viswanathan, Ananth C; Fitzke, Frederick W; Garway-Heath, David F

2006-11-01

To explore the summation properties of a motion-displacement hyperacuity stimulus with respect to stimulus area and luminance, with the goal of applying the results to the development of a motion-displacement test (MDT) for the detection of early glaucoma. A computer-generated line stimulus was presented with displacements randomized between 0 and 40 minutes of arc (min arc). Displacement thresholds (50% seen) were compared for stimuli of equal area but different edge length (orthogonal to the direction of motion) at four retinal locations. Also, MDT thresholds were recorded at five values of Michelson contrast (25%-84%) for each of five line lengths (11-128 min arc) at a single nasal location (-27,3). Frequency-of-seeing (FOS) curves were generated and displacement thresholds and interquartile ranges (IQR, 25%-75% seen) determined by probit analysis. Equivalent displacement thresholds were found for stimuli of equal area but half the edge length. Elevations of thresholds and IQR were demonstrated as line length and contrast were reduced. Equivalent displacement thresholds were also found for stimuli of equivalent energy (stimulus area x [stimulus luminance - background luminance]), in accordance with Ricco's law. There was a linear relationship (slope -0.5) between log MDT threshold and log stimulus energy. Stimulus area, rather than edge length, determined displacement thresholds within the experimental conditions tested. MDT thresholds are linearly related to the square root of the total energy of the stimulus. A new law, the threshold energy-displacement (TED) law, is proposed to apply to MDT summation properties, giving the relationship T = K logE where, T is the MDT threshold, Kis the constant, and E is the stimulus energy.

Using Stimulus Equivalence-Based Instruction to Teach Graduate Students in Applied Behavior Analysis to Interpret Operant Functions of Behavior

ERIC Educational Resources Information Center

Albright, Leif; Schnell, Lauren; Reeve, Kenneth F.; Sidener, Tina M.

2016-01-01

Stimulus equivalence-based instruction (EBI) was used to teach four, 4-member classes representing functions of behavior to ten graduate students. The classes represented behavior maintained by attention (Class 1), escape (Class 2), access to tangibles (Class 3), and automatic reinforcement (Class 4). Stimuli within each class consisted of a…

Emergence of relations and the essence of learning: a review of Sidman's Equivalence relations and behavior: a research story. Book review

NASA Technical Reports Server (NTRS)

Rumbaugh, D. M.

1995-01-01

The author reviews and comments on the book Equivalence relations and behavior: a research story by Murray Sidman. Sidman's book reports his research about equivalence relations and competencies in children with mental retardation and how it relates to behavior. Sidman used the idea of stimulus-stimulus relations among features of the environment to develop his theories about equivalence relations. Experimental work with children and animals demonstrated their ability to use equivalence relations to learn new tasks. The subject received feedback and reinforcement for specific choices made during training, then was presented with new choices during testing. Results of the tests indicate that subjects were able to establish relations and retrieve them in different situations.

Equivalence Class Formation in a Trace Stimulus Pairing Two-Response Format: Effects of Response Labels and Prior Programmed Transitivity Induction

ERIC Educational Resources Information Center

Fields, Lanny; Doran, Erica; Marroquin, Michael

2009-01-01

Three experiments identified factors that did and did not enhance the formation of two-node four-member equivalence classes when training and testing were conducted with trials presented in a trace stimulus pairing two-response (SP2R) format. All trials contained two separately presented stimuli. Half of the trials, called within-class trials,…

Toward a Technology of Derived Stimulus Relations: An Analysis of Articles Published in the "Journal of Applied Behavior Analysis," 1992-2009

ERIC Educational Resources Information Center

Rehfeldt, Ruth Anne

2011-01-01

Every article on stimulus equivalence or derived stimulus relations published in the "Journal of Applied Behavior Analysis" was evaluated in terms of characteristics that are relevant to the development of applied technologies: the type of participants, settings, procedure automated vs. tabletop), stimuli, and stimulus sensory modality; types of…

Teaching brain-behavior relations economically with stimulus equivalence technology.

PubMed

Fienup, Daniel M; Covey, Daniel P; Critchfield, Thomas S

2010-03-01

Instructional interventions based on stimulus equivalence provide learners with the opportunity to acquire skills that are not directly taught, thereby improving the efficiency of instructional efforts. The present report describes a study in which equivalence-based instruction was used to teach college students facts regarding brain anatomy and function. The instruction involved creating two classes of stimuli that students understood as being related. Because the two classes shared a common member, they spontaneously merged, thereby increasing the yield of emergent relations. Overall, students mastered more than twice as many facts as were explicitly taught, thus demonstrating the potential of equivalence-based instruction to reduce the amount of student investment that is required to master advanced academic topics.

Naming, the Formation of Stimulus Classes, and Applied Behavior Analysis.

ERIC Educational Resources Information Center

Stromer, Robert; And Others

1996-01-01

This review of research discusses how children with autism may acquire equivalence classes after learning to supply a common oral name to each stimulus in a potential class. A proposed methodology for researching referent naming and class formation, analysis of stimulus classes, and generalization is offered. (CR)

Event-related potential correlates of emergent inference in human arbitrary relational learning.

PubMed

Wang, Ting; Dymond, Simon

2013-01-01

Two experiments investigated the functional-anatomical correlates of cognition supporting untrained, emergent relational inference in a stimulus equivalence task. In Experiment 1, after learning a series of conditional relations involving words and pseudowords, participants performed a relatedness task during which EEG was recorded. Behavioural performance was faster and more accurate on untrained, indirectly related symmetry (i.e., learn AB and infer BA) and equivalence trials (i.e., learn AB and AC and infer CB) than on unrelated trials, regardless of whether or not a formal test for stimulus equivalence relations had been conducted. Consistent with previous results, event related potentials (ERPs) evoked by trained and emergent trials at parietal and occipital sites differed only for those participants who had not received a prior equivalence test. Experiment 2 further replicated and extended these behavioural and ERP findings using arbitrary symbols as stimuli and demonstrated time and frequency differences for trained and untrained relatedness trials. Overall, the findings demonstrate convincingly the ERP correlates of intra-experimentally established stimulus equivalence relations consisting entirely of arbitrary symbols and offer support for a contemporary cognitive-behavioural model of symbolic categorisation and relational inference. Copyright © 2012 Elsevier B.V. All rights reserved.

Naming, the formation of stimulus classes, and applied behavior analysis.

PubMed

Stromer, R; Mackay, H A; Remington, B

1996-01-01

The methods used in Sidman's original studies on equivalence classes provide a framework for analyzing functional verbal behavior. Sidman and others have shown how teaching receptive, name-referent matching may produce rudimentary oral reading and word comprehension skills. Eikeseth and Smith (1992) have extended these findings by showing that children with autism may acquire equivalence classes after learning to supply a common oral name to each stimulus in a potential class. A stimulus class analysis suggests ways to examine (a) the problem of programming generalization from teaching situations to other environments, (b) the expansion of the repertoires that occur in those settings, and (c) the use of naming to facilitate these forms of generalization. Such research will help to clarify and extend Horne and Lowe's recent (1996) account of the role of verbal behavior in the formation of stimulus classes.

Optimizing Equivalence-Based Instruction: Effects of Training Protocols on Equivalence Class Formation

ERIC Educational Resources Information Center

Fienup, Daniel M.; Wright, Nicole A.; Fields, Lanny

2015-01-01

Two experiments evaluated the effects of the simple-to-complex and simultaneous training protocols on the formation of academically relevant equivalence classes. The simple-to-complex protocol intersperses derived relations probes with training baseline relations. The simultaneous protocol conducts all training trials and test trials in separate…

Naming, the formation of stimulus classes, and applied behavior analysis.

PubMed Central

Stromer, R; Mackay, H A; Remington, B

1996-01-01

The methods used in Sidman's original studies on equivalence classes provide a framework for analyzing functional verbal behavior. Sidman and others have shown how teaching receptive, name-referent matching may produce rudimentary oral reading and word comprehension skills. Eikeseth and Smith (1992) have extended these findings by showing that children with autism may acquire equivalence classes after learning to supply a common oral name to each stimulus in a potential class. A stimulus class analysis suggests ways to examine (a) the problem of programming generalization from teaching situations to other environments, (b) the expansion of the repertoires that occur in those settings, and (c) the use of naming to facilitate these forms of generalization. Such research will help to clarify and extend Horne and Lowe's recent (1996) account of the role of verbal behavior in the formation of stimulus classes. PMID:8810064

Formation of new stimulus equivalence classes by exclusion.

PubMed

Plazas, Elberto A; Villamil, Carlos-Wilcen

2018-03-01

This study presents three experiments that aimed to show the formation of stimulus equivalence relations among stimuli that had been previously related only by exclusion. In Experiment 1, participants were trained on baseline conditional discriminations to establish two 3-member equivalence classes. Then, they were exposed to exclusion trials, without feedback, in which undefined stimuli had to be matched by rejecting the defined baseline stimuli. Finally, participants responded to test trials evaluating the emergence of symmetry and transitivity among the undefined stimuli from the exclusion trials. For half of the participants, the stimuli related by exclusion were introduced as S- stimuli in the baseline trials, whereas for the other half they were not. Further, half of the participants were assessed for emergent relations with stimuli from all the classes, whereas the other half was assessed for emergent relations with only the stimuli related by exclusion. In Experiment 2, the S- comparisons in the emergent relations test trials with stimuli only related by exclusion were stimuli from a null class. In Experiment 3, the number of exclusion trials was doubled. Across experiments, most participants showed emergence of equivalence relations among the stimuli related by exclusion. Some conditions of stimulus control associated with exclusion learning and the emergence of equivalence relations are discussed. © 2018 Society for the Experimental Analysis of Behavior.

Topography of Responses in Conditional Discrimination Influences Formation of Equivalence Classes

ERIC Educational Resources Information Center

Kato, Olivia M.; de Rose, Julio C.; Faleiros, Pedro B.

2008-01-01

The effects of response topography on stimulus class formation were studied in two experiments. In Experiment 1, 32 college students were assigned to 2 response topographies and 2 stimulus sets, in a 2 x 2 design. Students selected stimuli by either moving a mouse to lace an arrow-shaped cursor on the stimulus or pressing a key corresponding to…

Color Discrimination Is Affected by Modulation of Luminance Noise in Pseudoisochromatic Stimuli

PubMed Central

Cormenzana Méndez, Iñaki; Martín, Andrés; Charmichael, Teaire L.; Jacob, Mellina M.; Lacerda, Eliza M. C. B.; Gomes, Bruno D.; Fitzgerald, Malinda E. C.; Ventura, Dora F.; Silveira, Luiz C. L.; O'Donell, Beatriz M.; Souza, Givago S.

2016-01-01

Pseudoisochromatic stimuli have been widely used to evaluate color discrimination and to identify color vision deficits. Luminance noise is one of the stimulus parameters used to ensure that subject's response is due to their ability to discriminate target stimulus from the background based solely on the hue between the colors that compose such stimuli. We studied the influence of contrast modulation of the stimulus luminance noise on threshold and reaction time color discrimination. We evaluated color discrimination thresholds using the Cambridge Color Test (CCT) at six different stimulus mean luminances. Each mean luminance condition was tested using two protocols: constant absolute difference between maximum and minimum luminance of the luminance noise (constant delta protocol, CDP), and constant contrast modulation of the luminance noise (constant contrast protocol, CCP). MacAdam ellipses were fitted to the color discrimination thresholds in the CIE 1976 color space to quantify the color discrimination ellipses at threshold level. The same CDP and CCP protocols were applied in the experiment measuring RTs at three levels of stimulus mean luminance. The color threshold measurements show that for the CDP, ellipse areas decreased as a function of the mean luminance and they were significantly larger at the two lowest mean luminances, 10 cd/m2 and 13 cd/m2, compared to the highest one, 25 cd/m2. For the CCP, the ellipses areas also decreased as a function of the mean luminance, but there was no significant difference between ellipses areas estimated at six stimulus mean luminances. The exponent of the decrease of ellipse areas as a function of stimulus mean luminance was steeper in the CDP than CCP. Further, reaction time increased linearly with the reciprocal of the length of the chromatic vectors varying along the four chromatic half-axes. It decreased as a function of stimulus mean luminance in the CDP but not in the CCP. The findings indicated that visual performance using pseudoisochromatic stimuli was dependent on the Weber's contrast of the luminance noise. Low Weber's contrast in the luminance noise is suggested to have a reduced effect on chromatic information and, hence, facilitate desegregation of the hue-defined target from the background. PMID:27458404

Musical auditory stimulus acutely influences heart rate dynamic responses to medication in subjects with well-controlled hypertension.

PubMed

Martiniano, Eli Carlos; Santana, Milana Drumond Ramos; Barros, Érico Luiz Damasceno; do Socorro da Silva, Maria; Garner, David Matthew; de Abreu, Luiz Carlos; Valenti, Vitor E

2018-01-17

Music can improve the efficiency of medical treatment when correctly associated with drug action, reducing risk factors involving deteriorating cardiac function. We evaluated the effect of musical auditory stimulus associated with anti-hypertensive medication on heart rate (HR) autonomic control in hypertensive subjects. We evaluated 37 well-controlled hypertensive patients designated for anti-hypertensive medication. Heart rate variability (HRV) was calculated from the HR monitor recordings of two different, randomly sorted protocols (control and music) on two separate days. Patients were examined in a resting condition 10 minutes before medication and 20 minutes, 40 minutes and 60 minutes after oral medication. Music was played throughout the 60 minutes after medication with the same intensity for all subjects in the music protocol. We noted analogous response of systolic and diastolic arterial pressure in both protocols. HR decreased 60 minutes after medication in the music protocol while it remained unchanged in the control protocol. The effects of anti-hypertensive medication on SDNN (Standard deviation of all normal RR intervals), LF (low frequency, nu), HF (high frequency, nu) and alpha-1 scale were more intense in the music protocol. In conclusion, musical auditory stimulus increased HR autonomic responses to anti-hypertensive medication in well-controlled hypertensive subjects.

Electroencephalography (EEG) in the Study of Equivalence Class Formation. An Explorative Study.

PubMed

Arntzen, Erik; Steingrimsdottir, Hanna S

2017-01-01

Teaching arbitrary conditional discriminations and testing for derived relations may be essential for understanding changes in cognitive skills. Such conditional discrimination procedures are often used within stimulus equivalence research. For example, the participant is taught AB and BC relations and tested if emergent relations as BA, CB, AC and CA occur. The purpose of the current explorative experiment was to study stimulus equivalence class formation in older adults with electroencephalography (EEG) recordings as an additional measure. The EEG was used to learn about whether there was an indication of cognitive changes such as those observed in neurocognitive disorders (NCD). The present study included four participants who did conditional discrimination training and testing. The experimental design employed pre-class formation sorting and post-class formation sorting of the stimuli used in the experiment. EEG recordings were conducted before training, after training and after testing. The results showed that two participants formed equivalence classes, one participant failed in one of the three test relations, and one participant failed in two of the three test relations. This fourth participant also failed to sort the stimuli in accordance with the experimenter-defined stimulus equivalence classes during post-class formation sorting. The EEG indicated no cognitive decline in the first three participants but possible mild cognitive impairment (MCI) in the fourth participant. The results suggest that equivalence class formation may provide information about cognitive impairments such as those that are likely to occur in the early stages of NCD. The study recommends replications with broader samples.

Transportability of Equivalence-Based Programmed Instruction: Efficacy and Efficiency in a College Classroom

ERIC Educational Resources Information Center

Fienup, Daniel M.; Critchfield, Thomas S.

2011-01-01

College students in a psychology research-methods course learned concepts related to inferential statistics and hypothesis decision making. One group received equivalence-based instruction on conditional discriminations that were expected to promote the emergence of many untaught, academically useful abilities (i.e., stimulus equivalence group). A…

The Equivalence of Information-Theoretic and Likelihood-Based Methods for Neural Dimensionality Reduction

PubMed Central

Williamson, Ross S.; Sahani, Maneesh; Pillow, Jonathan W.

2015-01-01

Stimulus dimensionality-reduction methods in neuroscience seek to identify a low-dimensional space of stimulus features that affect a neuron’s probability of spiking. One popular method, known as maximally informative dimensions (MID), uses an information-theoretic quantity known as “single-spike information” to identify this space. Here we examine MID from a model-based perspective. We show that MID is a maximum-likelihood estimator for the parameters of a linear-nonlinear-Poisson (LNP) model, and that the empirical single-spike information corresponds to the normalized log-likelihood under a Poisson model. This equivalence implies that MID does not necessarily find maximally informative stimulus dimensions when spiking is not well described as Poisson. We provide several examples to illustrate this shortcoming, and derive a lower bound on the information lost when spiking is Bernoulli in discrete time bins. To overcome this limitation, we introduce model-based dimensionality reduction methods for neurons with non-Poisson firing statistics, and show that they can be framed equivalently in likelihood-based or information-theoretic terms. Finally, we show how to overcome practical limitations on the number of stimulus dimensions that MID can estimate by constraining the form of the non-parametric nonlinearity in an LNP model. We illustrate these methods with simulations and data from primate visual cortex. PMID:25831448

STIMULUS AND TRANSDUCER EFFECTS ON THRESHOLD

PubMed Central

Flamme, Gregory A.; Geda, Kyle; McGregor, Kara; Wyllys, Krista; Deiters, Kristy K.; Murphy, William J.; Stephenson, Mark R.

2015-01-01

Objective This study examined differences in thresholds obtained under Sennheiser HDA200 circumaural earphones using pure tone, equivalent rectangular noise bands, and 1/3 octave noise bands relative to thresholds obtained using Telephonics TDH-39P supra-aural earphones. Design Thresholds were obtained via each transducer and stimulus condition six times within a 10-day period. Study Sample Forty-nine adults were selected from a prior study to represent low, moderate, and high threshold reliability. Results The results suggested that (1) only small adjustments were needed to reach equivalent TDH-39P thresholds, (2) pure-tone thresholds obtained with HDA200 circumaural earphones had reliability equal to or better than those obtained using TDH-39P earphones, (3) the reliability of noise-band thresholds improved with broader stimulus bandwidth and was either equal to or better than pure-tone thresholds, and (4) frequency-specificity declined with stimulus bandwidths greater than one Equivalent Rectangular Band, which could complicate early detection of hearing changes that occur within a narrow frequency range. Conclusions These data suggest that circumaural earphones such as the HDA200 headphones provide better reliability for audiometric testing as compared to the TDH-39P earphones. These data support the use of noise bands, preferably ERB noises, as stimuli for audiometric monitoring. PMID:25549164

A Derived Transfer of Simple Discrimination and Self-Reported Arousal Functions in Spider Fearful and Non-Spider-Fearful Participants

ERIC Educational Resources Information Center

Smyth, Sinead; Barnes-Holmes, Dermot; Forsyth, John P.

2006-01-01

Two experiments investigated the derived transfer of functions through equivalence relations established using a stimulus pairing observation procedure. In Experiment 1, participants were trained on a simple discrimination (A1+/A2-) and then a stimulus pairing observation procedure was used to establish 4 stimulus pairings (A1-B1, A2-B2, B1-C1,…

Disentangling the nature of the nicotine stimulus.

PubMed

Bevins, Rick A; Barrett, Scott T; Polewan, Robert J; Pittenger, Steven T; Swalve, Natashia; Charntikov, Sergios

2012-05-01

Learning involving interoceptive stimuli likely plays an important role in many diseases and psychopathologies. Within this area, there has been extensive research investigating the interoceptive stimulus effects of abused drugs. In this pursuit, behavioral pharmacologists have taken advantage of what is known about learning processes and adapted the techniques to investigate the behavioral and receptor mechanisms of drug stimuli. Of particular interest is the nicotine stimulus and the use of the two-lever operant drug discrimination task and the Pavlovian drug discriminated goal-tracking task. There is strong concordance between the two methods when using "standard" testing protocols that minimize learning on test days. For example, ABT-418, nornicotine, and varenicline all fully evoked nicotine-appropriate responding. Notably, research from our laboratory with the discriminated goal-tracking task has used an alternative testing protocol. This protocol assesses stimulus substitution based on how well extinction learning using a non-nicotine ligand transfers back to the nicotine stimulus. These findings challenge conclusions based on more "standard" testing procedures (e.g., ABT-418 is not nicotine-like). As a starting point, we propose Thurstone scaling as a quantitative method for more precisely comparing transfer of extinction across doses, experiments, and investigators. We close with a discussion of future research directions and potential implications of the research for understanding interoceptive stimuli. Copyright © 2011 Elsevier B.V. All rights reserved.

Timing of pulsed electromagnetic field stimulation does not affect the promotion of bone cell development.

PubMed

Hannay, Gwynne; Leavesley, David; Pearcy, Mark

2005-12-01

Pulsed electromagnetic field (PEMF) devices have been used clinically to promote the healing of surgically resistant fractures in vivo. However, there is a sparsity of data on how the timing of an applied PEMF effects the osteogenic cells that would be present within the fracture gap. The purpose of this study was to examine the response of osteoblast-like cells to a PEMF stimulus, mimicking that of a clinically available device, using four protocols for the timing of the stimulus. The PEMF signal consisted of a 5 ms pulse burst (containing 20 pulses) repeated at 15 Hz. Cultures of a human osteosarcoma cell line, SaOS-2, were exposed to the four timing protocols, each conducted over 3 days. Protocol one stimulated the cells for 8 h each day, protocol two stimulated the cells for 24 h on the first day, protocol three stimulated the cells for 24 h on the second day, and protocol four stimulated the cells for 24 h on the third day. Cells were seeded with either 25,000 or 50,000 cells/well (24-well cell culture plates). All assays showed reduced proliferation and increased differentiation (alkaline phosphatase activity) in the PEMF stimulated cultures compared with the control cultures, except for protocol four alkaline phosphatase measurements. No clear trend was observed between the four protocols; however this may be due to cell density. The results indicated that an osteoblast-like cell line is responsive to a 15 Hz PEMF stimulus, which will stimulate the cell line to into an increasing state of maturity. Bioelectromagnetics (c) 2005 Wiley-Liss, Inc

Safe Use of Acoustic Vestibular-Evoked Myogenic Potential Stimuli: Protocol and Patient-Specific Considerations.

PubMed

Portnuff, Cory D F; Kleindienst, Samantha; Bogle, Jamie M

2017-09-01

Vestibular-evoked myogenic potentials (VEMPs) are commonly used clinical assessments for patients with complaints of dizziness. However, relatively high air-conducted stimuli are required to elicit the VEMP, and ultimately may compromise safe noise exposure limits. Recently, research has reported the potential for noise-induced hearing loss (NIHL) from VEMP stimulus exposure through studies of reduced otoacoustic emission levels after VEMP testing, as well as a recent case study showing permanent sensorineural hearing loss associated with VEMP exposure. The purpose of this report is to review the potential for hazardous noise exposure from VEMP stimuli and to suggest clinical parameters for safe VEMP testing. Literature review with presentation of clinical guidelines and a clinical tool for estimating noise exposure. The literature surrounding VEMP stimulus-induced hearing loss is reviewed, including several cases of overexposure. The article then presents a clinical calculation tool for the estimation of a patient's safe noise exposure from VEMP stimuli, considering stimulus parameters, and includes a discussion of how varying stimulus parameters affect a patient's noise exposure. Finally, recommendations are provided for recognizing and managing specific patient populations who may be at higher risk for NIHL from VEMP stimulus exposure. A sample protocol is provided that allows for safe noise exposure. VEMP stimuli have the potential to cause NIHL due to high sound exposure levels. However, with proper safety protocols in place, clinicians may reduce or eliminate this risk to their patients. Use of the tools provided, including the noise exposure calculation tool and sample protocols, may help clinicians to understand and ensure safe use of VEMP stimuli. American Academy of Audiology

Electroencephalography (EEG) in the Study of Equivalence Class Formation. An Explorative Study

PubMed Central

Arntzen, Erik; Steingrimsdottir, Hanna S.

2017-01-01

Teaching arbitrary conditional discriminations and testing for derived relations may be essential for understanding changes in cognitive skills. Such conditional discrimination procedures are often used within stimulus equivalence research. For example, the participant is taught AB and BC relations and tested if emergent relations as BA, CB, AC and CA occur. The purpose of the current explorative experiment was to study stimulus equivalence class formation in older adults with electroencephalography (EEG) recordings as an additional measure. The EEG was used to learn about whether there was an indication of cognitive changes such as those observed in neurocognitive disorders (NCD). The present study included four participants who did conditional discrimination training and testing. The experimental design employed pre-class formation sorting and post-class formation sorting of the stimuli used in the experiment. EEG recordings were conducted before training, after training and after testing. The results showed that two participants formed equivalence classes, one participant failed in one of the three test relations, and one participant failed in two of the three test relations. This fourth participant also failed to sort the stimuli in accordance with the experimenter-defined stimulus equivalence classes during post-class formation sorting. The EEG indicated no cognitive decline in the first three participants but possible mild cognitive impairment (MCI) in the fourth participant. The results suggest that equivalence class formation may provide information about cognitive impairments such as those that are likely to occur in the early stages of NCD. The study recommends replications with broader samples. PMID:28377704

Electrophysiology of Intuition: Pre-stimulus Responses in Group and Individual Participants Using a Roulette Paradigm

PubMed Central

Atkinson, Mike

2014-01-01

This study used electrophysiological measures of pre-stimulus effects that can occur prior to an unknown future event as an indicator of nonlocal intuition. Intuition in this context is considered as a process by which information normally outside the range of conscious awareness is detected at the cellular level by the heart, the brain, and the autonomic nervous system. This study extends the findings of previous experiments demonstrating that aspects of our physiology can respond to an emotionally engaging stimulus before it is actually experienced. The study evaluated a revised version of a roulette protocol, which included two pre-stimulus segments and included an analysis of the individual participant's data over eight separate trials in addition to a group-level analysis. We also assessed the potential effects of the moon phase on the pre-stimulus response outcomes and participant winning and amount won ratios. Data were collected under controlled laboratory conditions from 13 participants in 8 separate sessions using a modified version of a gambling paradigm protocol based on roulette. Half of the experimental sessions were conducted during the full moon phase and half during the new moon phase. Within each trial a total of three segments of physiological data were assessed. There were two separate pre-stimulus periods, pre-bet (4 sec) and postbet (12 sec), and a post-result period (6 sec). Participants were told that they were participating in a gambling experiment and were given an initial starting kitty and told they could keep any winnings over the course of 26 trials for each of the eight sessions. The physiological measures included the electrocardiogram (ECG), from which cardiac inter-beat-intervals (heart rate variability, HRV) were derived, and skin conductance. Before the participants participated in the first session, they completed the Cognitive Styles Index questionnaire, which assesses analytical vs intuitive styles. Overall, the results indicate that the revised protocol provides an effective objective measure for detecting a pre-stimulus response, which reflects a type of nonlocal intuition. We found significant differences between the win and loss responses in the aggregated physiological waveform data during both pre-stimulus segments, which provides important information about nonlocal intuition. On average, we detected a significant pre-stimulus response starting around 18 seconds prior to participants knowing the future outcome. Interestingly, there was not a strong overall relationship between the pre-stimulus responses and the amount of money the participants won or lost. We also found a significant difference in both pre-stimulus periods during the full moon phase but not in the new moon phase. The results suggest that the protocol is a reliable means of prompting physiological detection of pre-stimulus effects and can be used in future studies investigating aspects of nonlocal intuition. The findings also suggest that if participants had been able to become more attuned to their internal physiological responses, they would have performed much better on the betting choices they made. PMID:24808978

Contextual control using a go/no-go procedure with compound abstract stimuli.

PubMed

Modenesi, Rafael Diego; Debert, Paula

2015-05-01

Contextual control has been described as (1) a five-term contingency, in which the contextual stimulus exerts conditional control over conditional discriminations, and (2) allowing one stimulus to be a member of different equivalence classes without merging them into one. Matching-to-sample is the most commonly employed procedure to produce and study contextual control. The present study evaluated whether the go/no-go procedure with compound stimuli produces equivalence classes that share stimuli. This procedure does not allow the identification of specific stimulus functions (e.g., contextual, conditional, or discriminative functions). If equivalence classes were established with this procedure, then only the latter part of the contextual control definition (2) would be met. Six undergraduate students participated in the present study. In the training phases, responses to AC, BD, and XY compounds with stimuli from the same classes were reinforced, and responses to AC, BD, and XY compounds with stimuli from different classes were not. In addition, responses to X1A1B1, X1A2B2, X2A1B2, and X2A2B1 compounds were reinforced and responses to the other combinations were not. During the tests, the participants had to respond to new combinations of stimuli compounds YCD to indicate the formation of four equivalence classes that share stimuli: X1A1B1Y1C1D1, X1A2B2Y1C2D2, X2A1B2Y2C1D2, and X2A2B1Y2C2D1. Four of the six participants showed the establishment of these classes. These results indicate that establishing contextual stimulus functions is unnecessary to produce equivalence classes that share stimuli. Therefore, these results are inconsistent with the first part of the definition of contextual control. © Society for the Experimental Analysis of Behavior.

Contextual Control by Function and Form of Transfer of Functions

ERIC Educational Resources Information Center

Perkins, David R.; Dougher, Michael J.; Greenway, David E.

2007-01-01

This study investigated conditions leading to contextual control by stimulus topography over transfer of functions. Three 4-member stimulus equivalence classes, each consisting of four (A, B, C, D) topographically distinct visual stimuli, were established for 5 college students. Across classes, designated A stimuli were open-ended linear figures,…

Enhanced equivalence class formation by the delay and relational functions of meaningful stimuli.

PubMed

Arntzen, Erik; Nartey, Richard K; Fields, Lanny

2015-05-01

Undergraduates in six groups of 10 attempted to form three 3-node 5-member equivalence classes (A → B → C → D → E) under the simultaneous protocol. In five of six groups, all stimuli were abstract shapes; in the PIC group, C stimuli were pictures with the remainder being abstract shapes. Before class formation, participants in the Identity-S and Identity-D groups were given preliminary training to form identity conditional discriminations with the C stimuli using simultaneous and 6 s delayed matching-to-sample procedures, respectively. In the Arbitrary-S and Arbitrary-D groups, before class formation, arbitrary conditional discriminations were formed between C and X stimuli using simultaneous and 6 s delayed matching-to-sample procedures, respectively. With no preliminary training, classes in the PIC and ABS groups were formed by 80% and 0% of participants, respectively. After preliminary training, class formation (yield) increased with delay, regardless of relational type. For each of the two delays, yield was slightly greater after forming arbitrary- instead of identity-relations. Yield was greatest, however, when a class contained a meaningful stimulus (PIC). During failed class formation, probes produced experimenter-defined relations, participant-defined relations, and unsystematic responding; delay, but not the relation type in preliminary training influenced relational and indeterminate responding. These results suggest how meaningful stimuli enhance equivalence class formation. © Society for the Experimental Analysis of Behavior.

The transfer of Cfunc contextual control through equivalence relations.

PubMed

Perez, William F; Fidalgo, Adriana P; Kovac, Roberta; Nico, Yara C

2015-05-01

Derived relational responding is affected by contextual stimuli (Cfunc) that select specific stimulus functions. The present study investigated the transfer of Cfunc contextual control through equivalence relations by evaluating both (a) the maintenance of Cfunc contextual control after the expansion of a relational network, and (b) the establishment of novel contextual stimuli by the transfer of Cfunc contextual control through equivalence relations. Initially, equivalence relations were established and contingencies were arranged so that colors functioned as Cfunc stimuli controlling participants' key-pressing responses in the presence of any stimulus from a three-member equivalence network. To investigate the first research question, the three-member equivalence relations were expanded to five members and the novel members were presented with the Cfunc stimuli in the key-pressing task. To address the second goal of this study, the colors (Cfunc) were established as equivalent to certain line patterns. The transfer of contextual cue function (Cfunc) was tested replacing the colored backgrounds with line patterns in the key-pressing task. Results suggest that the Cfunc contextual control was transferred to novel stimuli that were added to the relational network. In addition, the line patterns indirectly acquired the contextual cue function (Cfunc) initially established for the colored backgrounds. The conceptual and applied implications of Cfunc contextual control are discussed. © Society for the Experimental Analysis of Behavior.

Cardinal Equivalence of Small Number in Young Children.

ERIC Educational Resources Information Center

Kingma, J.; Roelinga, U.

1982-01-01

Children completed three types of equivalent cardination tasks which assessed the influence of different stimulus configurations (linear, linear-nonlinear, and nonlinear), and density of object spacing. Prior results reported by Siegel, Brainerd, and Gelman and Gallistel were not replicated. Implications for understanding cardination concept…

Neural correlates of sample-coding and reward-coding in the delay activity of neurons in the entopallium and nidopallium caudolaterale of pigeons (Columba livia).

PubMed

Johnston, Melissa; Anderson, Catrona; Colombo, Michael

2017-01-15

We recorded neuronal activity from the nidopallium caudolaterale, the avian equivalent of mammalian prefrontal cortex, and the entopallium, the avian equivalent of the mammalian visual cortex, in four birds trained on a differential outcomes delayed matching-to-sample procedure in which one sample stimulus was followed by reward and the other was not. Despite similar incidence of reward-specific and reward-unspecific delay cell types across the two areas, overall entopallium delay activity occurred following both rewarded and non-rewarded stimuli, whereas nidopallium caudolaterale delay activity tended to occur following the rewarded stimulus but not the non-rewarded stimulus. These findings are consistent with the view that delay activity in entopallium represents a code of the sample stimulus whereas delay activity in nidopallium caudolaterale represents a code of the possibility of an upcoming reward. However, based on the types of delay cells encountered, cells in NCL also code the sample stimulus and cells in ENTO are influenced by reward. We conclude that both areas support the retention of information, but that the activity in each area is differentially modulated by factors such as reward and attentional mechanisms. Copyright © 2016 Elsevier B.V. All rights reserved.

Rudimentary Reading Repertoires via Stimulus Equivalence and Recombination of Minimal Verbal Units

PubMed Central

Matos, Maria Amelia; Avanzi, Alessandra Lopes; McIlvane, William J

2006-01-01

We report a study with sixteen low-SES Brazilian children that sought to establish a repertoire of relations involving dictated words, printed words, and corresponding pictures. Children were taught: (1) in response to dictated words, to select corresponding pictures; (2) in response to syllables presented in both visual and auditory formats, to select words which contained a corresponding syllable in either the first or the last position; (3) in response to dictated-word samples, to “construct” corresponding printed words via arranging their constituent syllabic components; and (4) in response to printed word samples, to construct identical printed words by arranging their syllabic constituents. After training on the first two types of tasks, children were given tests for potentially emergent relations involving printed words and pictures. Almost all exhibited relations consistent with stimulus equivalence. They also displayed emergent naming performances––not only with training words but also with new words that were recombinations of their constituent syllables. The present work was inspired by Sidman's stimulus equivalence paradigm and by Skinner's functional analysis of verbal relations, particularly as applied to conceptions of minimal behavioral units and creativity (i.e., behavioral flexibility) in the analytical units applied to verbal relations. PMID:22477340

Improving accuracy of portion-size estimations through a stimulus equivalence paradigm.

PubMed

Hausman, Nicole L; Borrero, John C; Fisher, Alyssa; Kahng, SungWoo

2014-01-01

The prevalence of obesity continues to increase in the United States (Gordon-Larsen, The, & Adair, 2010). Obesity can be attributed, in part, to overconsumption of energy-dense foods. Given that overeating plays a role in the development of obesity, interventions that teach individuals to identify and consume appropriate portion sizes are warranted. Specifically, interventions that teach individuals to estimate portion sizes correctly without the use of aids may be critical to the success of nutrition education programs. The current study evaluated the use of a stimulus equivalence paradigm to teach 9 undergraduate students to estimate portion size accurately. Results suggested that the stimulus equivalence paradigm was effective in teaching participants to make accurate portion size estimations without aids, and improved accuracy was observed in maintenance sessions that were conducted 1 week after training. Furthermore, 5 of 7 participants estimated the target portion size of novel foods during extension sessions. These data extend existing research on teaching accurate portion-size estimations and may be applicable to populations who seek treatment (e.g., overweight or obese children and adults) to teach healthier eating habits. © Society for the Experimental Analysis of Behavior.

High-intensity interval training in patients with coronary heart disease: Prescription models and perspectives.

PubMed

Ribeiro, Paula A B; Boidin, Maxime; Juneau, Martin; Nigam, Anil; Gayda, Mathieu

2017-01-01

Recently, high-intensity interval training (HIIT) has emerged as an alternative and/or complementary exercise modality to continuous aerobic exercise training (CAET) in CHD patients. However, the literature contains descriptions of many HIIT protocols with different stage durations, nature of recovery and intensities. In this review, we discuss the most recent forms of validated HIIT protocols in patients with coronary heart disease (CHD) and how to prescribe and use them during short- and long-term (phase II and III) cardiac rehabilitation programs. We also compare the superior and/or equivalent short- and long-term effects of HIIT versus CAET on aerobic fitness, cardiovascular function, and quality of life; their efficiency, safety, and tolerance; and exercise adherence. Short interval HIIT was found beneficial for CHD patients with lower aerobic fitness and would ideally be used in initiation and improvement stages. Medium and/or long interval HIIT protocols may be beneficial for CHD patients with higher aerobic fitness, and would be ideally used in the improvement and maintenance stages because of their high physiological stimulus. Finally, we propose progressive individualized models of HIIT programs (phase II to III) for patients with CHD and how to ideally use them according to the clinical status of patients and phase of the cardiac rehabilitation program. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Effects of muscarinic blockade in perirhinal cortex during visual recognition

PubMed Central

Tang, Yi; Mishkin, Mortimer; Aigner, Thomas G.

1997-01-01

Stimulus recognition in monkeys is severely impaired by destruction or dysfunction of the perirhinal cortex and also by systemic administration of the cholinergic-muscarinic receptor blocker, scopolamine. These two effects are shown here to be linked: Stimulus recognition was found to be significantly impaired after bilateral microinjection of scopolamine directly into the perirhinal cortex, but not after equivalent injections into the laterally adjacent visual area TE or into the dentate gyrus of the overlying hippocampal formation. The results suggest that the formation of stimulus memories depends critically on cholinergic-muscarinic activation of the perirhinal area, providing a new clue to how stimulus representations are stored. PMID:9356507

Toward a technology of derived stimulus relations: an analysis of articles published in the journal of applied behavior analysis, 1992-2009.

PubMed

Rehfeldt, Ruth Anne

2011-01-01

Every article on stimulus equivalence or derived stimulus relations published in the Journal of Applied Behavior Analysis was evaluated in terms of characteristics that are relevant to the development of applied technologies: the type of participants, settings, procedure (automated vs. tabletop), stimuli, and stimulus sensory modality; types of relations targeted and emergent skills demonstrated by participants; and presence versus absence of evaluation of generalization and maintenance. In most respects, published reports suggested the possibility of applied technologies but left the difficult work of technology development to future investigations, suggestions for which are provided.

Appetitive but Not Aversive Olfactory Conditioning Modifies Antennal Movements in Honeybees

ERIC Educational Resources Information Center

Cholé, Hanna; Junca, Pierre; Sandoz, Jean-Christophe

2015-01-01

In honeybees, two olfactory conditioning protocols allow the study of appetitive and aversive Pavlovian associations. Appetitive conditioning of the proboscis extension response (PER) involves associating an odor, the conditioned stimulus (CS) with a sucrose solution, the unconditioned stimulus (US). Conversely, aversive conditioning of the sting…

On Learning to Talk: Are Principles Derived from the Learning Laboratory Applicable?

ERIC Educational Resources Information Center

Palermo, David S.

While studies in learning and verbal behavior show that learning comes through paired-associate problems, they do not explain the acquisition of language. Three paradigms demonstrate mediation effect in paired-associate learning: response equivalence, stimulus equivalence, and chaining model. By reviewing children's language acquisition patterns…

Stimulus control: Part II

PubMed Central

Dinsmoor, James A.

1995-01-01

The second part of my tutorial stresses the systematic importance of two parameters of discrimination training: (a) the magnitude of the physical difference between the positive and the negative stimulus (disparity) and (b) the magnitude of the difference between the positive stimulus, in particular, and the background stimulation (salience). It then examines the role these variables play in such complex phenomena as blocking and overshadowing, progressive discrimination training, and the transfer of control by fading. It concludes by considering concept formation and imitation, which are important forms of application, and recent work on equivalence relations. PMID:22478222

Reversible photo-chem-electrotriggered three-state luminescence switching based on core-shell nanostructures

NASA Astrophysics Data System (ADS)

Zhai, Yanling; Zhu, Zhijun; Zhu, Chengzhou; Zhu, Jinbo; Ren, Jiangtao; Wang, Erkang; Dong, Shaojun

2013-05-01

Reversible three-state fluorescence switches triggered by light, electricity and chemical inputs based on ``sponges'' of Pyronin Y-doped silica nanoparticles (PYDS) and polyoxometalate K14[Na(H2O)P5W30O110] (Na-POMs) core-shell nanostructures were realized. Under one or two signal inputs, the system exhibited distinct three-state interconvertible automaton, achieving reversible ``on'' and ``off'' luminescence switches via the related luminescence quenching effect. The features of the system correspond to the equivalent circuitry of an IMPLICATION logic gate performing the Boolean operation by using potential and chemical as inputs. Such a multi-chromic device with novel structure possesses several advantages, such as relative low operation voltage, large reproducibility and reversibility, apparent fluorescence contrast, and long-time stability, which make it a suitable candidate for nonvolatile memory devices. In addition, the current protocol for the hybrid film fabrication can be easily extended from the polyoxometalate and organic dyes to other novel nanostructures matched multifunctional stimulus-responsive species and fluorescence materials in the future.Reversible three-state fluorescence switches triggered by light, electricity and chemical inputs based on ``sponges'' of Pyronin Y-doped silica nanoparticles (PYDS) and polyoxometalate K14[Na(H2O)P5W30O110] (Na-POMs) core-shell nanostructures were realized. Under one or two signal inputs, the system exhibited distinct three-state interconvertible automaton, achieving reversible ``on'' and ``off'' luminescence switches via the related luminescence quenching effect. The features of the system correspond to the equivalent circuitry of an IMPLICATION logic gate performing the Boolean operation by using potential and chemical as inputs. Such a multi-chromic device with novel structure possesses several advantages, such as relative low operation voltage, large reproducibility and reversibility, apparent fluorescence contrast, and long-time stability, which make it a suitable candidate for nonvolatile memory devices. In addition, the current protocol for the hybrid film fabrication can be easily extended from the polyoxometalate and organic dyes to other novel nanostructures matched multifunctional stimulus-responsive species and fluorescence materials in the future. Electronic supplementary information (ESI) available: Experimental details and instrumentation; electrochemical, fluorescence and absorption spectra characterizations of hybrid films. See DOI: 10.1039/c3nr00254c

Emergent conditional relations in a Go/No-Go procedure: figure-ground and stimulus-position compound relations.

PubMed

Debert, Paula; Huziwara, Edson M; Faggiani, Robson Brino; De Mathis, Maria Eugênia Simões; McIlvane, William J

2009-09-01

Past research has demonstrated emergent conditional relations using a go/no-go procedure with pairs of figures displayed side-by-side on a computer screen. The present study sought to extend applications of this procedure. In Experiment 1, we evaluated whether emergent conditional relations could be demonstrated when two-component stimuli were displayed in figure-ground relationships-abstract figures displayed on backgrounds of different colors. Five normally capable adults participated. During training, each two-component stimulus was presented successively. Responses emitted in the presence of some stimulus pairs (A1B1, A2B2, A3B3, B1C1, B2C2 and B3C3) were reinforced, whereas responses emitted in the presence of other pairs (A1B2, A1B3, A2B1, A2B3, A3B1, A3B2, B1C2, B1C3, B2C1, B2C3, B3C1 and B3C2) were not. During tests, new configurations (AC and CA) were presented, thus emulating structurally the matching-to-sample tests employed in typical equivalence studies. All participants showed emergent relations consistent with stimulus equivalence during testing. In Experiment 2, we systematically replicated the procedures with stimulus compounds consisting of four figures (A1, A2, C1 and C2) and two locations (left - B1 and right - B2). All 6 normally capable adults exhibited emergent stimulus-stimulus relations. Together, these experiments show that the go/no-go procedure is a potentially useful alternative for studying emergent conditional relations when matching-to-sample is procedurally cumbersome or impossible to use.

The Acute Effect of Upper-Body Complex Training on Power Output of Martial Art Athletes as Measured by the Bench Press Throw Exercise

PubMed Central

Liossis, Loudovikos Dimitrios; Forsyth, Jacky; Liossis, Ceorge; Tsolakis, Charilaos

2013-01-01

The purpose of this study was to examine the acute effect of upper body complex training on power output, as well as to determine the requisite preload intensity and intra-complex recovery interval needed to induce power output increases. Nine amateur-level combat/martial art athletes completed four distinct experimental protocols, which consisted of 5 bench press repetitions at either: 65% of one-repetition maximum (1RM) with a 4 min rest interval; 65% of 1RM with an 8 min rest; 85% of 1RM with a 4 min rest; or 85% of 1RM with an 8 min rest interval, performed on different days. Before (pre-conditioning) and after (post-conditioning) each experimental protocol, three bench press throws at 30% of 1RM were performed. Significant differences in power output pre-post conditioning were observed across all experimental protocols (F=26.489, partial eta2=0.768, p=0.001). Mean power output significantly increased when the preload stimulus of 65% 1RM was matched with 4 min of rest (p=0.001), and when the 85% 1RM preload stimulus was matched with 8 min of rest (p=0.001). Moreover, a statistically significant difference in power output was observed between the four conditioning protocols (F= 21.101, partial eta2=0.913, p=0.001). It was concluded that, in complex training, matching a heavy preload stimulus with a longer rest interval, and a lighter preload stimulus with a shorter rest interval is important for athletes wishing to increase their power production before training or competition. PMID:24511352

Comparing topography-based verbal behavior with stimulus selection-based verbal behavior

PubMed Central

Sundberg, Carl T.; Sundberg, Mark L.

1990-01-01

Michael (1985) distinguished between two types of verbal behavior: topography-based and stimulus selection-based verbal behavior. The current research was designed to empirically examine these two types of verbal behavior while addressing the frequently debated question, Which augmentative communication system should be used with the nonverbal developmentally disabled person? Four mentally retarded adults served as subjects. Each subject was taught to tact an object by either pointing to its corresponding symbol (selection-based verbal behavior), or making the corresponding sign (topography-based verbal behavior). They were then taught an intraverbal relation, and were tested for the emergence of stimulus equivalence relations. The results showed that signed responses were acquired more readily than pointing responses as measured by the acquisition of tacts and intraverbals, and the formation of equivalence classes. These results support Michael's (1985) analysis, and have important implications for the design of language intervention programs for the developmentally disabled. ImagesFig. 1Fig. 2 PMID:22477602

A Comparison of Match-to-Sample and Respondent-Type Training of Equivalence Classes

ERIC Educational Resources Information Center

Clayton, Michael C.; Hayes, Linda J.

2004-01-01

Throughout the 25-year history of research on stimulus equivalence, one feature of the training procedure has remained constant, namely, the requirement of operant responding during the training procedures. The present investigation compared the traditional match-to-sample (MTS) training with a more recent respondent-type (ReT) procedure. Another…

Some Tests of Response Membership in Acquired Equivalence Classes

ERIC Educational Resources Information Center

Urcuioli, Peter J.; Lionello-DeNolf, Karen; Michalek, Sarah; Vasconcelos, Marco

2006-01-01

Pigeons were trained on many-to-one matching in which pairs of samples, each consisting of a visual stimulus and a distinctive pattern of center-key responding, occasioned the same reinforced comparison choice. Acquired equivalence between the visual and response samples then was evaluated by reinforcing new comparison choices to one set of…

Simulation of axonal excitability using a Spreadsheet template created in Microsoft Excel.

PubMed

Brown, A M

2000-08-01

The objective of this present study was to implement an established simulation protocol (A.M. Brown, A methodology for simulating biological systems using Microsoft Excel, Comp. Methods Prog. Biomed. 58 (1999) 181-90) to model axonal excitability. The simulation protocol involves the use of in-cell formulas directly typed into a spreadsheet and does not require any programming skills or use of the macro language. Once the initial spreadsheet template has been set up the simulations described in this paper can be executed with a few simple keystrokes. The model axon contained voltage-gated ion channels that were modeled using Hodgkin Huxley style kinetics. The basic properties of axonal excitability modeled were: (1) threshold of action potential firing, demonstrating that not only are the stimulus amplitude and duration critical in the generation of an action potential, but also the resting membrane potential; (2) refractoriness, the phenomenon of reduced excitability immediately following an action potential. The difference between the absolute refractory period, when no amount of stimulus will elicit an action potential, and relative refractory period, when an action potential may be generated by applying increased stimulus, was demonstrated with regard to the underlying state of the Na(+) and K(+) channels; (3) temporal summation, a process by which two sub-threshold stimuli can unite to elicit an action potential was shown to be due to conductance changes outlasting the first stimulus and summing with the second stimulus-induced conductance changes to drive the membrane potential past threshold; (4) anode break excitation, where membrane hyperpolarization was shown to produce an action potential by removing Na(+) channel inactivation that is present at resting membrane potential. The simulations described in this paper provide insights into mechanisms of axonal excitation that can be carried out by following an easily understood protocol.

Construction and Operation of a High-Speed, High-Precision Eye Tracker for Tight Stimulus Synchronization and Real-Time Gaze Monitoring in Human and Animal Subjects.

PubMed

Farivar, Reza; Michaud-Landry, Danny

2016-01-01

Measurements of the fast and precise movements of the eye-critical to many vision, oculomotor, and animal behavior studies-can be made non-invasively by video oculography. The protocol here describes the construction and operation of a research-grade video oculography system with ~0.1° precision over the full typical viewing range at over 450 Hz with tight synchronization with stimulus onset. The protocol consists of three stages: (1) system assembly, (2) calibration for both cooperative, and for minimally cooperative subjects (e.g., animals or infants), and (3) gaze monitoring and recording.

It’s The Information!

PubMed Central

Ward, Ryan D.; Gallistel, C.R.; Balsam, Peter D

2013-01-01

Learning in conditioning protocols has long been thought to depend on temporal contiguity between the conditioned stimulus and the unconditioned stimulus. This conceptualization has led to a preponderance of associative models of conditioning. We suggest that trial-based associative models that posit contiguity as the primary principle underlying learning are flawed, and provide a brief review of an alternative, information theoretic approach to conditioning. The information that a CS conveys about the timing of the next US can be derived from the temporal parameters of a conditioning protocol. According to this view, a CS will support conditioned responding if, and only if, it reduces uncertainty about the timing of the next US. PMID:23384660

Assessment and Treatment of Selective Mutism: Recommendations and a Case Study.

ERIC Educational Resources Information Center

Sheridan, Susan M.; And Others

1995-01-01

Presents results of stimulus fading procedure used to treat a six-year-old girl with elective mutism. Presents assessment protocol that features procedures that can be used to render a diagnosis and assist in treatment planning. Results suggest stimulus fading of new persons into the school setting was effective in producing speech. (JBJ)

Is Conscious Stimulus Identification Dependent on Knowledge of the Perceptual Modality? Testing the “Source Misidentification Hypothesis”

PubMed Central

Overgaard, Morten; Lindeløv, Jonas; Svejstrup, Stinna; Døssing, Marianne; Hvid, Tanja; Kauffmann, Oliver; Mouridsen, Kim

2013-01-01

This paper reports an experiment intended to test a particular hypothesis derived from blindsight research, which we name the “source misidentification hypothesis.” According to this hypothesis, a subject may be correct about a stimulus without being correct about how she had access to this knowledge (whether the stimulus was visual, auditory, or something else). We test this hypothesis in healthy subjects, asking them to report whether a masked stimulus was presented auditorily or visually, what the stimulus was, and how clearly they experienced the stimulus using the Perceptual Awareness Scale (PAS). We suggest that knowledge about perceptual modality may be a necessary precondition in order to issue correct reports of which stimulus was presented. Furthermore, we find that PAS ratings correlate with correctness, and that subjects are at chance level when reporting no conscious experience of the stimulus. To demonstrate that particular levels of reporting accuracy are obtained, we employ a statistical strategy, which operationally tests the hypothesis of non-equality, such that the usual rejection of the null-hypothesis admits the conclusion of equivalence. PMID:23508677

Testing Response-Stimulus Equivalence Relations Using Differential Responses as a Sample

ERIC Educational Resources Information Center

Shimizu, Hirofumi

2006-01-01

This study tested the notion that an equivalence relation may include a response when differential responses are paired with stimuli presented during training. Eight normal adults learned three kinds of computer mouse movements as differential response topographies (R1, R2, and R3). Next, in matching-to-sample training, one of the response…

The acute effect of a plyometric stimulus on jump performance in professional rugby players.

PubMed

Tobin, Daniel P; Delahunt, Eamonn

2014-02-01

Post-activation potentiation (PAP) is the elevation of motor performance to a higher level in response to a conditioning stimulus. Extensive research exists examining the PAP effect after a heavy resistance exercise. However, there is limited research examining the PAP effect after a plyometric stimulus. This study was designed to examine whether a plyometric stimulus could produce a PAP effect comparable to that typically reported with a heavy resistance protocol. Importantly, it was hypothesized that the PAP effect would exist without the same levels of acute fatigue resulting from a heavy stimulus, thus allowing improvement in performance within a short rest interval range. Twenty professional rugby players were recruited for the study. Subjects performed 2 countermovement jumps (CMJs) at baseline and at 1, 3, and 5 minutes after a plyometric stimulus consisting of 40 jumps. Two separate 1-way repeated-measures analyses of variance were conducted to compare the dependent variables CMJ height and peak force at the 4 time points. Results of the Bonferroni adjusted pairwise comparisons indicated that jump height and peak force before plyometric exercises were significantly lower than all other time points (p < 0.01). The main finding of this study indicates that a series of plyometric exercises causes a significant acute enhancement in CMJ height (p < 0.01) and peak force (p < 0.01) throughout the rest interval range of 1-5 minutes. The plyometric series induced an improvement in CMJ height comparable to that reported elsewhere after a heavy lifting stimulus but without the need for a prolonged rest interval. Performing repeated series of plyometric jumps appears to be an efficient method of taking advantage of the PAP phenomenon, thus possibly eliminating the need for a complex training protocol.

Benefits of Stimulus Exposure: Developmental Learning Independent of Task Performance

PubMed Central

Green, David B.; Ohlemacher, Jocelyn; Rosen, Merri J.

2016-01-01

Perceptual learning (training-induced performance improvement) can be elicited by task-irrelevant stimulus exposure in humans. In contrast, task-irrelevant stimulus exposure in animals typically disrupts perception in juveniles while causing little to no effect in adults. This may be due to the extent of exposure, which is brief in humans while chronic in animals. Here we assessed the effects of short bouts of passive stimulus exposure on learning during development in gerbils, compared with non-passive stimulus exposure (i.e., during testing). We used prepulse inhibition of the acoustic startle response, a method that can be applied at any age, to measure gap detection thresholds across four age groups, spanning development. First, we showed that both gap detection thresholds and gap detection learning across sessions displayed a long developmental trajectory, improving throughout the juvenile period. Additionally, we demonstrated larger within- and across-animal performance variability in younger animals. These results are generally consistent with results in humans, where there are extended developmental trajectories for both the perception of temporally-varying signals, and the effects of perceptual training, as well as increased variability and poorer performance consistency in children. We then chose an age (mid-juveniles) that displayed clear learning over sessions in order to assess effects of brief passive stimulus exposure on this learning. We compared learning in mid-juveniles exposed to either gap detection testing (gaps paired with startles) or equivalent gap exposure without testing (gaps alone) for three sessions. Learning was equivalent in both these groups and better than both naïve age-matched animals and controls receiving no gap exposure but only startle testing. Thus, short bouts of exposure to gaps independent of task performance is sufficient to induce learning at this age, and is as effective as gap detection testing. PMID:27378837

Stimulus-response learning in long-term cocaine users: acquired equivalence and probabilistic category learning.

PubMed

Vadhan, Nehal P; Myers, Catherine E; Rubin, Eric; Shohamy, Daphna; Foltin, Richard W; Gluck, Mark A

2008-01-11

The purpose of this study was to examine stimulus-response (S-R) learning in active cocaine users. Twenty-two cocaine-dependent participants (20 males and 2 females) and 21 non-drug using control participants (19 males and 2 females) who were similar in age and education were administered two computerized learning tasks. The Acquired Equivalence task initially requires learning of simple antecedent-consequent discriminations, but later requires generalization of this learning when the stimuli are presented in novel recombinations. The Weather Prediction task requires the prediction of a dichotomous outcome based on different stimuli combinations when the stimuli predict the outcome only probabilistically. On the Acquired Equivalence task, cocaine users made significantly more errors than control participants when required to learn new discriminations while maintaining previously learned discriminations, but performed similarly to controls when required to generalize this learning. No group differences were seen on the Weather Prediction task. Cocaine users' learning of stimulus discriminations under conflicting response demands was impaired, but their ability to generalize this learning once they achieved criterion was intact. This performance pattern is consistent with other laboratory studies of long-term cocaine users that demonstrated that established learning interfered with new learning on incremental learning tasks, relative to healthy controls, and may reflect altered dopamine transmission in the basal ganglia of long-term cocaine users.

It's the information!

PubMed

Ward, Ryan D; Gallistel, C R; Balsam, Peter D

2013-05-01

Learning in conditioning protocols has long been thought to depend on temporal contiguity between the conditioned stimulus and the unconditioned stimulus. This conceptualization has led to a preponderance of associative models of conditioning. We suggest that trial-based associative models that posit contiguity as the primary principle underlying learning are flawed, and provide a brief review of an alternative, information theoretic approach to conditioning. The information that a CS conveys about the timing of the next US can be derived from the temporal parameters of a conditioning protocol. According to this view, a CS will support conditioned responding if, and only if, it reduces uncertainty about the timing of the next US. Copyright © 2013 Elsevier B.V. All rights reserved.

The effects of sweep numbers per average and protocol type on the accuracy of the p300-based concealed information test.

PubMed

Dietrich, Ariana B; Hu, Xiaoqing; Rosenfeld, J Peter

2014-03-01

In the first of two experiments, we compared the accuracy of the P300 concealed information test protocol as a function of numbers of trials experienced by subjects and ERP averages analyzed by investigators. Contrary to Farwell et al. (Cogn Neurodyn 6(2):115-154, 2012), we found no evidence that 100 trial based averages are more accurate than 66 or 33 trial based averages (all numbers led to accuracies of 84-94 %). There was actually a trend favoring the lowest trial numbers. The second study compared numbers of irrelevant stimuli recalled and recognized in the 3-stimulus protocol versus the complex trial protocol (Rosenfeld in Memory detection: theory and application of the concealed information test, Cambridge University Press, New York, pp 63-89, 2011). Again, in contrast to expectations from Farwell et al. (Cogn Neurodyn 6(2):115-154, 2012), there were no differences between protocols, although there were more irrelevant stimuli recognized than recalled, and irrelevant 4-digit number group stimuli were neither recalled nor recognized as well as irrelevant city name stimuli. We therefore conclude that stimulus processing in the P300-based complex trial protocol-with no more than 33 sweep averages-is adequate to allow accurate detection of concealed information.

Transfers of stimulus function during roulette wagering.

PubMed

Dixon, Mark R; Enoch, Mary Rachel; Belisle, Jordan

2017-10-01

Twenty-five recreational gamblers were initially asked to place bets on either red or black positions on a roulette board in a simulated casino setting. Each participant was then exposed to a stimulus pairing observing procedure which attempted to develop equivalence classes between one color (black or red) and traditionally positive words (e.g., love, happy, sex) and another color (black or red) and traditionally negative words (e.g., death, cancer, taxes), in the absence of consequence manipulations. Twenty-one of the twenty-five participants demonstrated greater response allocation to the color position on the roulette board that participated in a relational network with the positive words. Variations in sequencing of experimental conditions had no impact on poststimulus-pairing wagers, but did impact tests for equivalence accuracy. © 2017 Society for the Experimental Analysis of Behavior.

Automatic and Controlled Response Inhibition: Associative Learning in the Go/No-Go and Stop-Signal Paradigms

PubMed Central

Verbruggen, Frederick; Logan, Gordon D.

2008-01-01

In five experiments, the authors examined the development of automatic response inhibition in the go/no-go paradigm and a modified version of the stop-signal paradigm. They hypothesized that automatic response inhibition may develop over practice when stimuli are consistently associated with stopping. All five experiments consisted of a training phase and a test phase in which the stimulus mapping was reversed for a subset of the stimuli. Consistent with the automatic-inhibition hypothesis, the authors found that responding in the test phase was slowed when the stimulus had been consistently associated with stopping in the training phase. In addition, they found that response inhibition benefited from consistent stimulus-stop associations. These findings suggest that response inhibition may rely on the retrieval of stimulus-stop associations after practice with consistent stimulus-stop mappings. Stimulus-stop mapping is typically consistent in the go/no-go paradigm, so automatic inhibition is likely to occur. However, stimulus-stop mapping is typically inconsistent in the stop-signal paradigm, so automatic inhibition is unlikely to occur. Thus, the results suggest that the two paradigms are not equivalent because they allow different kinds of response inhibition. PMID:18999358

Schistosoma mansoni: cercarial responses to irradiance changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saladin, K.S.

1982-02-01

Cercariae of Schistosoma mansoni alternate between active swimming and passive drifting. They began swimming in response to either an increase or decrease in irradiance experienced during the passive phase. The number of cercariae reacting to a shadow was proportional to the magnitude of the stimulus. The shadow response may be mediated by the cercaria's ciliary receptors. About half as many cercariae reacted to an irradiance increase as to an equivalent decrease. This report is the first quantitative study of photosensory stimulus-response relationships in schistosome cercariae.

Translational Vestibulo-Ocular Reflex and Motion Perception During Interaural Linear Acceleration: Comparison of Different Motion Paradigms

NASA Technical Reports Server (NTRS)

Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, S. J.

2011-01-01

The neural mechanisms to resolve ambiguous tilt-translation motion have been hypothesized to be different for motion perception and eye movements. Previous studies have demonstrated differences in ocular and perceptual responses using a variety of motion paradigms, including Off-Vertical Axis Rotation (OVAR), Variable Radius Centrifugation (VRC), translation along a linear track, and tilt about an Earth-horizontal axis. While the linear acceleration across these motion paradigms is presumably equivalent, there are important differences in semicircular canal cues. The purpose of this study was to compare translation motion perception and horizontal slow phase velocity to quantify consistencies, or lack thereof, across four different motion paradigms. Twelve healthy subjects were exposed to sinusoidal interaural linear acceleration between 0.01 and 0.6 Hz at 1.7 m/s/s (equivalent to 10 tilt) using OVAR, VRC, roll tilt, and lateral translation. During each trial, subjects verbally reported the amount of perceived peak-to-peak lateral translation and indicated the direction of motion with a joystick. Binocular eye movements were recorded using video-oculography. In general, the gain of translation perception (ratio of reported linear displacement to equivalent linear stimulus displacement) increased with stimulus frequency, while the phase did not significantly vary. However, translation perception was more pronounced during both VRC and lateral translation involving actual translation, whereas perceptions were less consistent and more variable during OVAR and roll tilt which did not involve actual translation. For each motion paradigm, horizontal eye movements were negligible at low frequencies and showed phase lead relative to the linear stimulus. At higher frequencies, the gain of the eye movements increased and became more inphase with the acceleration stimulus. While these results are consistent with the hypothesis that the neural computational strategies for motion perception and eye movements differ, they also indicate that the specific motion platform employed can have a significant effect on both the amplitude and phase of each.

TRANSFER OF AVERSIVE RESPONDENT ELICITATION IN ACCORDANCE WITH EQUIVALENCE RELATIONS

PubMed Central

Valverde, Miguel RodrÍguez; Luciano, Carmen; Barnes-Holmes, Dermot

2009-01-01

The present study investigates the transfer of aversively conditioned respondent elicitation through equivalence classes, using skin conductance as the measure of conditioning. The first experiment is an attempt to replicate Experiment 1 in Dougher, Augustson, Markham, Greenway, and Wulfert (1994), with different temporal parameters in the aversive conditioning procedure employed. Match-to-sample procedures were used to teach 17 participants two 4-member equivalence classes. Then, one member of one class was paired with electric shock and one member of the other class was presented without shock. The remaining stimuli from each class were presented in transfer tests. Unlike the findings in the original study, transfer of conditioning was not achieved. In Experiment 2, similar procedures were used with 30 participants, although several modifications were introduced (formation of five-member classes, direct conditioning with several elements of each class, random sequences of stimulus presentation in transfer tests, reversal in aversive conditioning contingencies). More than 80% of participants who had shown differential conditioning also showed the transfer of function effect. Moreover, this effect was replicated within subjects for 3 participants. This is the first demonstration of the transfer of aversive respondent elicitation through stimulus equivalence classes with the presentation of transfer test trials in random order. The latter prevents the possibility that transfer effects are an artefact of transfer test presentation order. PMID:20119523

Situated Naïve Physics: Task Constraints Decide what Children Know about Density

PubMed Central

Kloos, Heidi; Fisher, Anna; Van Orden, Guy C.

2013-01-01

Children’s understanding of density is riddled with misconceptions – or so it seems. Yet even preschoolers at times appear to understand density. This article seeks to reconcile these conflicting outcomes by investigating the nature of constraints available in different experimental protocols. Protocols that report misconceptions about density used stimulus arrangements that make differences in mass and volume more salient than differences in density. In contrast, protocols that report successful performance used stimulus arrangements that might have increased the salience of density. To test this hypothesis, the present experiments manipulate the salience of object density. Children between 2 and 9 years of age and adults responded whether an object would sink or float when placed in water. Results indicated that children’s performance on exactly the same objects differed as a function of the saliency of the dimension of density, relative to the dimensions of mass and volume. These results support the idea that constraints – rather than stable knowledge – drive performance, with implications for teaching children about non-obvious concepts such as density. PMID:20853994

On the origins of naming and other symbolic behavior

PubMed Central

Horne, Pauline J.; Lowe, C. Fergus

1996-01-01

We identify naming as the basic unit of verbal behavior, describe the conditions under which it is learned, and outline its crucial role in the development of stimulus classes and, hence, of symbolic behavior. Drawing upon B. F. Skinner's functional analysis and the theoretical work of G. H. Mead and L. S. Vygotsky, we chart how a child, through learning listener behavior and then echoic responding, learns bidirectional relations between classes of objects or events and his or her own speaker-listener behavior, thus acquiring naming—a higher order behavioral relation. Once established, the bidirectionality incorporated in naming extends across behavior classes such as those identified by Skinner as the mand, tact, and intraverbal so that each becomes a variant of the name relation. We indicate how our account informs the specification of rule-governed behavior and provides the basis for an experimental analysis of symbolic behavior. Furthermore, because naming is both evoked by, and itself evokes, classes of events it brings about new or emergent behavior such as that reported in studies of stimulus equivalence. This account is supported by data from a wide range of match-to-sample studies that also provide evidence that stimulus equivalence in humans is not a unitary phenomenon but the outcome of a number of different types of naming behavior. PMID:16812780

Inferring consistent functional interaction patterns from natural stimulus FMRI data

PubMed Central

Sun, Jiehuan; Hu, Xintao; Huang, Xiu; Liu, Yang; Li, Kaiming; Li, Xiang; Han, Junwei; Guo, Lei

2014-01-01

There has been increasing interest in how the human brain responds to natural stimulus such as video watching in the neuroimaging field. Along this direction, this paper presents our effort in inferring consistent and reproducible functional interaction patterns under natural stimulus of video watching among known functional brain regions identified by task-based fMRI. Then, we applied and compared four statistical approaches, including Bayesian network modeling with searching algorithms: greedy equivalence search (GES), Peter and Clark (PC) analysis, independent multiple greedy equivalence search (IMaGES), and the commonly used Granger causality analysis (GCA), to infer consistent and reproducible functional interaction patterns among these brain regions. It is interesting that a number of reliable and consistent functional interaction patterns were identified by the GES, PC and IMaGES algorithms in different participating subjects when they watched multiple video shots of the same semantic category. These interaction patterns are meaningful given current neuroscience knowledge and are reasonably reproducible across different brains and video shots. In particular, these consistent functional interaction patterns are supported by structural connections derived from diffusion tensor imaging (DTI) data, suggesting the structural underpinnings of consistent functional interactions. Our work demonstrates that specific consistent patterns of functional interactions among relevant brain regions might reflect the brain's fundamental mechanisms of online processing and comprehension of video messages. PMID:22440644

Color-dependent learning in restrained Africanized honey bees.

PubMed

Jernigan, C M; Roubik, D W; Wcislo, W T; Riveros, A J

2014-02-01

Associative color learning has been demonstrated to be very poor using restrained European honey bees unless the antennae are amputated. Consequently, our understanding of proximate mechanisms in visual information processing is handicapped. Here we test learning performance of Africanized honey bees under restrained conditions with visual and olfactory stimulation using the proboscis extension response (PER) protocol. Restrained individuals were trained to learn an association between a color stimulus and a sugar-water reward. We evaluated performance for 'absolute' learning (learned association between a stimulus and a reward) and 'discriminant' learning (discrimination between two stimuli). Restrained Africanized honey bees (AHBs) readily learned the association of color stimulus for both blue and green LED stimuli in absolute and discriminatory learning tasks within seven presentations, but not with violet as the rewarded color. Additionally, 24-h memory improved considerably during the discrimination task, compared with absolute association (15-55%). We found that antennal amputation was unnecessary and reduced performance in AHBs. Thus color learning can now be studied using the PER protocol with intact AHBs. This finding opens the way towards investigating visual and multimodal learning with application of neural techniques commonly used in restrained honey bees.

Learning and generalization from reward and punishment in opioid addiction.

PubMed

Myers, Catherine E; Rego, Janice; Haber, Paul; Morley, Kirsten; Beck, Kevin D; Hogarth, Lee; Moustafa, Ahmed A

2017-01-15

This study adapts a widely-used acquired equivalence paradigm to investigate how opioid-addicted individuals learn from positive and negative feedback, and how they generalize this learning. The opioid-addicted group consisted of 33 participants with a history of heroin dependency currently in a methadone maintenance program; the control group consisted of 32 healthy participants without a history of drug addiction. All participants performed a novel variant of the acquired equivalence task, where they learned to map some stimuli to correct outcomes in order to obtain reward, and to map other stimuli to correct outcomes in order to avoid punishment; some stimuli were implicitly "equivalent" in the sense of being paired with the same outcome. On the initial training phase, both groups performed similarly on learning to obtain reward, but as memory load grew, the control group outperformed the addicted group on learning to avoid punishment. On a subsequent testing phase, the addicted and control groups performed similarly on retention trials involving previously-trained stimulus-outcome pairs, as well as on generalization trials to assess acquired equivalence. Since prior work with acquired equivalence tasks has associated stimulus-outcome learning with the nigrostriatal dopamine system, and generalization with the hippocampal region, the current results are consistent with basal ganglia dysfunction in the opioid-addicted patients. Further, a selective deficit in learning from punishment could contribute to processes by which addicted individuals continue to pursue drug use even at the cost of negative consequences such as loss of income and the opportunity to engage in other life activities. Published by Elsevier B.V.

Dendrites Enable a Robust Mechanism for Neuronal Stimulus Selectivity.

PubMed

Cazé, Romain D; Jarvis, Sarah; Foust, Amanda J; Schultz, Simon R

2017-09-01

Hearing, vision, touch: underlying all of these senses is stimulus selectivity, a robust information processing operation in which cortical neurons respond more to some stimuli than to others. Previous models assume that these neurons receive the highest weighted input from an ensemble encoding the preferred stimulus, but dendrites enable other possibilities. Nonlinear dendritic processing can produce stimulus selectivity based on the spatial distribution of synapses, even if the total preferred stimulus weight does not exceed that of nonpreferred stimuli. Using a multi-subunit nonlinear model, we demonstrate that stimulus selectivity can arise from the spatial distribution of synapses. We propose this as a general mechanism for information processing by neurons possessing dendritic trees. Moreover, we show that this implementation of stimulus selectivity increases the neuron's robustness to synaptic and dendritic failure. Importantly, our model can maintain stimulus selectivity for a larger range of loss of synapses or dendrites than an equivalent linear model. We then use a layer 2/3 biophysical neuron model to show that our implementation is consistent with two recent experimental observations: (1) one can observe a mixture of selectivities in dendrites that can differ from the somatic selectivity, and (2) hyperpolarization can broaden somatic tuning without affecting dendritic tuning. Our model predicts that an initially nonselective neuron can become selective when depolarized. In addition to motivating new experiments, the model's increased robustness to synapses and dendrites loss provides a starting point for fault-resistant neuromorphic chip development.

Two-dimensional adaptation in the auditory forebrain

PubMed Central

Nagel, Katherine I.; Doupe, Allison J.

2011-01-01

Sensory neurons exhibit two universal properties: sensitivity to multiple stimulus dimensions, and adaptation to stimulus statistics. How adaptation affects encoding along primary dimensions is well characterized for most sensory pathways, but if and how it affects secondary dimensions is less clear. We studied these effects for neurons in the avian equivalent of primary auditory cortex, responding to temporally modulated sounds. We showed that the firing rate of single neurons in field L was affected by at least two components of the time-varying sound log-amplitude. When overall sound amplitude was low, neural responses were based on nonlinear combinations of the mean log-amplitude and its rate of change (first time differential). At high mean sound amplitude, the two relevant stimulus features became the first and second time derivatives of the sound log-amplitude. Thus a strikingly systematic relationship between dimensions was conserved across changes in stimulus intensity, whereby one of the relevant dimensions approximated the time differential of the other dimension. In contrast to stimulus mean, increases in stimulus variance did not change relevant dimensions, but selectively increased the contribution of the second dimension to neural firing, illustrating a new adaptive behavior enabled by multidimensional encoding. Finally, we demonstrated theoretically that inclusion of time differentials as additional stimulus features, as seen so prominently in the single-neuron responses studied here, is a useful strategy for encoding naturalistic stimuli, because it can lower the necessary sampling rate while maintaining the robustness of stimulus reconstruction to correlated noise. PMID:21753019

Coactivation of response initiation processes with redundant signals.

PubMed

Maslovat, Dana; Hajj, Joëlle; Carlsen, Anthony N

2018-05-14

During reaction time (RT) tasks, participants respond faster to multiple stimuli from different modalities as compared to a single stimulus, a phenomenon known as the redundant signal effect (RSE). Explanations for this effect typically include coactivation arising from the multiple stimuli, which results in enhanced processing of one or more response production stages. The current study compared empirical RT data with the predictions of a model in which initiation-related activation arising from each stimulus is additive. Participants performed a simple wrist extension RT task following either a visual go-signal, an auditory go-signal, or both stimuli with the auditory stimulus delayed between 0 and 125 ms relative to the visual stimulus. Results showed statistical equivalence between the predictions of an additive initiation model and the observed RT data, providing novel evidence that the RSE can be explained via a coactivation of initiation-related processes. It is speculated that activation summation occurs at the thalamus, leading to the observed facilitation of response initiation. Copyright © 2018 Elsevier B.V. All rights reserved.

Emergent Verbal Behavior and Analogy: Skinnerian and Linguistic Approaches

PubMed Central

Matos, Maria Amelia; de Lourdes Passos, Maria

2010-01-01

The production of verbal operants not previously taught is an important aspect of language productivity. For Skinner, new mands, tacts, and autoclitics result from the recombination of verbal operants. The relation between these mands, tacts, and autoclitics is what linguists call analogy, a grammatical pattern that serves as a foundation on which a speaker might emit new linguistic forms. Analogy appears in linguistics as a regularity principle that characterizes language and has been related to how languages change and also to creativity. The approaches of neogrammarians like Hermann Paul, as well as those of Jespersen and Bloomfield, appear to have influenced Skinner's understanding of verbal creativity. Generalization and stimulus equivalence are behavioral processes related to the generative grammatical behavior described in the analogy model. Linguistic forms and grammatical patterns described in analogy are part of the contingencies of reinforcement that produce generalization and stimulus equivalence. The analysis of verbal behavior needs linguistic analyses of the constituents of linguistic forms and their combination patterns. PMID:22479127

A comprehensive protocol to diagnose and treat pain of muscular origin may successfully and reliably decrease or eliminate pain in a chronic pain population.

PubMed

Marcus, Norman J; Gracely, Edward J; Keefe, Kelly O

2010-01-01

A comprehensive protocol is presented to identify muscular causes of regional pain syndromes utilizing an electrical stimulus in lieu of palpation, and combining elements of Prolotherapy with trigger point injections. One hundred seventy-six consecutive patients were evaluated for the presence of muscle pain by utilizing an electrical stimulus produced by the Muscle Pain Detection Device. The diagnosis of "Muscle Pain Amenable to Injection" (MPAI), rather than trigger points, was made if pain was produced for the duration of the stimulation. If MPAI was found, muscle tendon injections (MTI) were offered to patients along with post-MTI physical therapy, providing neuromuscular electrical stimulation followed by a validated exercise program [1]. A control group, evaluated 1 month prior to their actual consultation/evaluation when muscle pain was identified but not yet treated, was used for comparison. Forty-five patients who met criteria completed treatment. Patients' scores on the Brief Pain Inventory decreased an average of 62%; median 70% (P < 0.001) for pain severity and 68%; median 85% (P < 0.001) for pain interference one month following treatment. These changes were significantly greater (P < 0.001) than those observed in the untreated controls. A protocol incorporating an easily reproducible electrical stimulus to diagnose a muscle causing pain in a region of the body followed by an injection technique that involves the entirety of the muscle, and post injection restoration of muscle function, can successfully eliminate or significantly reduce regional pain present for years.

Nonequivalence of two flavors of oblivious transfer at the quantum level

DOE Office of Scientific and Technical Information (OSTI.GOV)

He Guangping; Wang, Z. D.; Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong

2006-04-15

Though all-or-nothing oblivious transfer and one-out-of-two oblivious transfer are equivalent in classical cryptography, we here show that a protocol built upon secure quantum all-or-nothing oblivious transfer cannot satisfy the rigorous definition of quantum one-out-of-two oblivious transfer due to the nature of quantum cryptography. Thus the securities of the two oblivious transfer protocols are not equivalent at the quantum level.

Merging separately established stimulus classes with outcome-specific reinforcement.

PubMed

Johnson, Cammarie; Meleshkevich, Olga; Dube, William V

2014-01-01

This study extended previous research on equivalence relations established with outcome-specific reinforcers to include the merger of separately established stimulus classes. Participants were four adults. Conditional discriminations AC and BC were trained first. Correct selections of C1 (C2, or C3) in the presence of A1 or B1 (A2 or B2, or A3 or B3) were followed by red (blue, or white) tokens; tokens were exchanged for value added to three participant-selected gift cards. Outcomes on equivalence tests for three-member classes ABC were positive. DF and EF were trained with the same reinforcing consequences, and tests were positive for three-member classes DEF. Results of class merger tests with combinations of stimuli from the ABC and DEF classes (AD, FB, etc.) were immediately positive for two participants, demonstrating six-member classes ABCDEF with reinforcers as nodes. Merger tests for a third participant were initially negative but became positive after brief exposure to unreinforced probe trials with reinforcers as comparison stimuli. Following class merger, tests for matching the reinforcers to samples and comparisons were also positive. Class-merger test results were negative for a fourth participant. The results provide the first demonstration of eight-member equivalence classes including two outcome-specific conditioned reinforcing stimuli. © Society for the Experimental Analysis of Behavior.

Multisensory perceptual learning is dependent upon task difficulty.

PubMed

De Niear, Matthew A; Koo, Bonhwang; Wallace, Mark T

2016-11-01

There has been a growing interest in developing behavioral tasks to enhance temporal acuity as recent findings have demonstrated changes in temporal processing in a number of clinical conditions. Prior research has demonstrated that perceptual training can enhance temporal acuity both within and across different sensory modalities. Although certain forms of unisensory perceptual learning have been shown to be dependent upon task difficulty, this relationship has not been explored for multisensory learning. The present study sought to determine the effects of task difficulty on multisensory perceptual learning. Prior to and following a single training session, participants completed a simultaneity judgment (SJ) task, which required them to judge whether a visual stimulus (flash) and auditory stimulus (beep) presented in synchrony or at various stimulus onset asynchronies (SOAs) occurred synchronously or asynchronously. During the training session, participants completed the same SJ task but received feedback regarding the accuracy of their responses. Participants were randomly assigned to one of three levels of difficulty during training: easy, moderate, and hard, which were distinguished based on the SOAs used during training. We report that only the most difficult (i.e., hard) training protocol enhanced temporal acuity. We conclude that perceptual training protocols for enhancing multisensory temporal acuity may be optimized by employing audiovisual stimuli for which it is difficult to discriminate temporal synchrony from asynchrony.

Programmable Mechanobioreactor for Exploration of the Effects of Periodic Vibratory Stimulus on Mesenchymal Stem Cell Differentiation

PubMed Central

Cashion, Avery T.; Caballero, Montserrat; Halevi, Alexandra; Pappa, Andrew; Dennis, Robert G.

2014-01-01

Abstract A programmable bioreactor using a voice-coil actuator was developed to enable research on the effects of periodic vibratory stimulus on human and porcine mesenchymal stem cells (MSCs). We hypothesized that low frequency vibrations would result in a cartilage phenotype and higher frequency vibrations would result in a bone phenotype. The mechanical stimulation protocol is adjusted from a computer external to the incubator via a USB cable. Once programmed, the embedded microprocessor and sensor system on the bioreactor execute the protocol independent of the computer. In each test, a sinusoidal stimulus was applied to a culture plate in 1-min intervals with a 15-min rest following each, for a total of 15 h per day for 10 days. Frequencies of 1 and 100 Hz were applied to cultures of both human and porcine umbilical cord–derived MSCs. Chondrogenesis was determined by Alcian blue staining for glycosaminoglycans and an increased differentiation index (ratio of mRNA for collagen II and collagen I). Osteogenic differentiation was indicated with Alizarin red for calcium staining and increased bone morphogenetic protein 2 mRNA. One-hertz stimulation resulted in a cartilage phenotype for both human and porcine MSCs, while 100-Hz stimulation resulted in a bone phenotype. PMID:24570842

Experimental provocation of 'ice-cream headache' by ice cubes and ice water.

PubMed

Mages, Stephan; Hensel, Ole; Zierz, Antonia Maria; Kraya, Torsten; Zierz, Stephan

2017-04-01

Background There are various studies on experimentally provoked 'ice-cream headache' or 'headache attributed to ingestion or inhalation of a cold stimulus' (HICS) using different provocation protocols. The aim of this study was to compare two provocation protocols. Methods Ice cubes pressed to the palate and fast ingestion of ice water were used to provoke HICS and clinical features were compared. Results The ice-water stimulus provoked HICS significantly more often than the ice-cube stimulus (9/77 vs. 39/77). Ice-water-provoked HICS had a significantly shorter latency (median 15 s, range 4-97 s vs. median 68 s, range 27-96 s). There was no difference in pain localisation. Character after ice-cube stimulation was predominantly described as pressing and after ice-water stimulation as stabbing. A second HICS followed in 10/39 (26%) of the headaches provoked by ice water. Lacrimation occurred significantly more often in volunteers with than in those without HICS. Discussion HICS provoked by ice water was more frequent, had a shorter latency, different pain character and higher pain intensity than HICS provoked by ice cubes. The finding of two subsequent HICS attacks in the same volunteers supports the notion that two types of HICS exist. Lacrimation during HICS indicates involvement of the trigeminal-autonomic reflex.

Measurement of Visual Reaction Times Using Hand-held Mobile Devices

NASA Technical Reports Server (NTRS)

Mulligan, Jeffrey B.; Arsintescu, Lucia; Flynn-Evans, Erin

2015-01-01

Modern mobile devices provide a convenient platform for collecting research data in the field. But,because the working of these devices is often cloaked behind multiple layers of proprietary system software, it can bedifficult to assess the accuracy of the data they produce, particularly in the case of timing. We have been collecting datain a simple visual reaction time experiment, as part of a fatigue testing protocol known as the Psychomotor Vigilance Test (PVT). In this protocol, subjects run a 5-minute block consisting of a sequence of trials in which a visual stimulus appears after an unpredictable variable delay. The subject is required to tap the screen as soon as possible after the appearance of the stimulus. In order to validate the reaction times reported by our program, we had subjects perform the task while a high-speed video camera recorded both the display screen, and a side view of the finger (observed in a mirror). Simple image-processing methods were applied to determine the frames in which the stimulus appeared and disappeared, and in which the finger made and broke contact with the screen. The results demonstrate a systematic delay between the initial contact by the finger and the detection of the touch by the software, having a value of 80 +- 20 milliseconds.

Perceptual grouping enhances visual plasticity.

PubMed

Mastropasqua, Tommaso; Turatto, Massimo

2013-01-01

Visual perceptual learning, a manifestation of neural plasticity, refers to improvements in performance on a visual task achieved by training. Attention is known to play an important role in perceptual learning, given that the observer's discriminative ability improves only for those stimulus feature that are attended. However, the distribution of attention can be severely constrained by perceptual grouping, a process whereby the visual system organizes the initial retinal input into candidate objects. Taken together, these two pieces of evidence suggest the interesting possibility that perceptual grouping might also affect perceptual learning, either directly or via attentional mechanisms. To address this issue, we conducted two experiments. During the training phase, participants attended to the contrast of the task-relevant stimulus (oriented grating), while two similar task-irrelevant stimuli were presented in the adjacent positions. One of the two flanking stimuli was perceptually grouped with the attended stimulus as a consequence of its similar orientation (Experiment 1) or because it was part of the same perceptual object (Experiment 2). A test phase followed the training phase at each location. Compared to the task-irrelevant no-grouping stimulus, orientation discrimination improved at the attended location. Critically, a perceptual learning effect equivalent to the one observed for the attended location also emerged for the task-irrelevant grouping stimulus, indicating that perceptual grouping induced a transfer of learning to the stimulus (or feature) being perceptually grouped with the task-relevant one. Our findings indicate that no voluntary effort to direct attention to the grouping stimulus or feature is necessary to enhance visual plasticity.

Relational Learning in Children with Deafness and Cochlear Implants

ERIC Educational Resources Information Center

Almeida-Verdu, Ana Claudia; Huziwara, Edson M.; de Souza, Deisy G.; de Rose, Julio C.; Bevilacqua, Maria Cecilia; Lopes, Jair, Jr.; Alves, Cristiane O.; McIlvane, William J.

2008-01-01

This four-experiment series sought to evaluate the potential of children with neurosensory deafness and cochlear implants to exhibit auditory-visual and visual-visual stimulus equivalence relations within a matching-to-sample format. Twelve children who became deaf prior to acquiring language (prelingual) and four who became deaf afterwards…

Extinction, reacquisition, and rapid forgetting of eyeblink conditioning in developing rats

PubMed Central

Freeman, John H.

2014-01-01

Eyeblink conditioning is a well-established model for studying the developmental neurobiology of associative learning and memory. However, age differences in extinction and subsequent reacquisition have yet to be studied using this model. The present study examined extinction and reacquisition of eyeblink conditioning in developing rats. In Experiment 1, post-natal day (P) 17 and 24 rats were trained to a criterion of 80% conditioned responses (CRs) using stimulation of the middle cerebellar peduncle (MCP) as a conditioned stimulus (CS). Stimulation CS-alone extinction training commenced 24 h later, followed by reacquisition training after the fourth extinction session. Contrary to expected results, rats trained starting on P17 showed significantly fewer CRs to stimulation CS-alone presentations relative to P24s, including fewer CRs as early as the first block of extinction session 1. Furthermore, the P17 group was slower to reacquire following extinction. Experiment 2 was run to determine the extent to which the low CR percentage observed in P17s early in extinction reflected rapid forgetting versus rapid extinction. Twenty-four hours after reaching criterion, subjects were trained in a session split into 50 stimulation CS-unconditioned stimulus paired trials followed immediately by 50 stimulation CS-alone trials. With this “immediate” extinction protocol, CR percentages during the first block of stimulation CS-alone presentations were equivalent to terminal acquisition levels at both ages but extinction was more rapid in the P17 group. These findings indicate that forgetting is observed in P17 relative to P24 rats 24 h following acquisition. The forgetting in P17 rats has important implications for the neurobiological mechanisms of memory in the developing cerebellum. PMID:25403458

The working memory stroop effect: when internal representations clash with external stimuli.

PubMed

Kiyonaga, Anastasia; Egner, Tobias

2014-08-01

Working memory (WM) has recently been described as internally directed attention, which implies that WM content should affect behavior exactly like an externally perceived and attended stimulus. We tested whether holding a color word in WM, rather than attending to it in the external environment, can produce interference in a color-discrimination task, which would mimic the classic Stroop effect. Over three experiments, the WM Stroop effect recapitulated core properties of the classic attentional Stroop effect, displaying equivalent congruency effects, additive contributions from stimulus- and response-level congruency, and susceptibility to modulation by the percentage of congruent and incongruent trials. Moreover, WM maintenance was inversely related to attentional demands during the WM delay between stimulus presentation and recall, with poorer memory performance following incongruent than congruent trials. Together, these results suggest that WM and attention rely on the same resources and operate over the same representations. © The Author(s) 2014.

Stimulus information contaminates summation tests of independent neural representations of features

NASA Technical Reports Server (NTRS)

Shimozaki, Steven S.; Eckstein, Miguel P.; Abbey, Craig K.

2002-01-01

Many models of visual processing assume that visual information is analyzed into separable and independent neural codes, or features. A common psychophysical test of independent features is known as a summation study, which measures performance in a detection, discrimination, or visual search task as the number of proposed features increases. Improvement in human performance with increasing number of available features is typically attributed to the summation, or combination, of information across independent neural coding of the features. In many instances, however, increasing the number of available features also increases the stimulus information in the task, as assessed by an optimal observer that does not include the independent neural codes. In a visual search task with spatial frequency and orientation as the component features, a particular set of stimuli were chosen so that all searches had equivalent stimulus information, regardless of the number of features. In this case, human performance did not improve with increasing number of features, implying that the improvement observed with additional features may be due to stimulus information and not the combination across independent features.

78 FR 8090 - Misuse of Internet Protocol (IP) Captioned Telephone Service; Telecommunications Relay Services...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-05

... communicate in a manner that is functionally equivalent to communication by conventional voice telephone users... actually need the service to communicate in a manner that is functionally equivalent to communication by... equivalent to communication by conventional voice telephone users. In fact, the unobtrusive nature of IP CTS...

A method for real-time visual stimulus selection in the study of cortical object perception.

PubMed

Leeds, Daniel D; Tarr, Michael J

2016-06-01

The properties utilized by visual object perception in the mid- and high-level ventral visual pathway are poorly understood. To better establish and explore possible models of these properties, we adopt a data-driven approach in which we repeatedly interrogate neural units using functional Magnetic Resonance Imaging (fMRI) to establish each unit's image selectivity. This approach to imaging necessitates a search through a broad space of stimulus properties using a limited number of samples. To more quickly identify the complex visual features underlying human cortical object perception, we implemented a new functional magnetic resonance imaging protocol in which visual stimuli are selected in real-time based on BOLD responses to recently shown images. Two variations of this protocol were developed, one relying on natural object stimuli and a second based on synthetic object stimuli, both embedded in feature spaces based on the complex visual properties of the objects. During fMRI scanning, we continuously controlled stimulus selection in the context of a real-time search through these image spaces in order to maximize neural responses across pre-determined 1cm(3) rain regions. Elsewhere we have reported the patterns of cortical selectivity revealed by this approach (Leeds et al., 2014). In contrast, here our objective is to present more detailed methods and explore the technical and biological factors influencing the behavior of our real-time stimulus search. We observe that: 1) Searches converged more reliably when exploring a more precisely parameterized space of synthetic objects; 2) real-time estimation of cortical responses to stimuli is reasonably consistent; 3) search behavior was acceptably robust to delays in stimulus displays and subject motion effects. Overall, our results indicate that real-time fMRI methods may provide a valuable platform for continuing study of localized neural selectivity, both for visual object representation and beyond. Copyright © 2016 Elsevier Inc. All rights reserved.

A method for real-time visual stimulus selection in the study of cortical object perception

PubMed Central

Leeds, Daniel D.; Tarr, Michael J.

2016-01-01

The properties utilized by visual object perception in the mid- and high-level ventral visual pathway are poorly understood. To better establish and explore possible models of these properties, we adopt a data-driven approach in which we repeatedly interrogate neural units using functional Magnetic Resonance Imaging (fMRI) to establish each unit’s image selectivity. This approach to imaging necessitates a search through a broad space of stimulus properties using a limited number of samples. To more quickly identify the complex visual features underlying human cortical object perception, we implemented a new functional magnetic resonance imaging protocol in which visual stimuli are selected in real-time based on BOLD responses to recently shown images. Two variations of this protocol were developed, one relying on natural object stimuli and a second based on synthetic object stimuli, both embedded in feature spaces based on the complex visual properties of the objects. During fMRI scanning, we continuously controlled stimulus selection in the context of a real-time search through these image spaces in order to maximize neural responses across predetermined 1 cm3 brain regions. Elsewhere we have reported the patterns of cortical selectivity revealed by this approach (Leeds 2014). In contrast, here our objective is to present more detailed methods and explore the technical and biological factors influencing the behavior of our real-time stimulus search. We observe that: 1) Searches converged more reliably when exploring a more precisely parameterized space of synthetic objects; 2) Real-time estimation of cortical responses to stimuli are reasonably consistent; 3) Search behavior was acceptably robust to delays in stimulus displays and subject motion effects. Overall, our results indicate that real-time fMRI methods may provide a valuable platform for continuing study of localized neural selectivity, both for visual object representation and beyond. PMID:26973168

Learning and generalization from reward and punishment in opioid addiction

PubMed Central

Myers, Catherine E.; Rego, Janice; Haber, Paul; Morley, Kirsten; Beck, Kevin D.; Hogarth, Lee; Moustafa, Ahmed A.

2016-01-01

This study adapts a widely-used acquired equivalence paradigm to investigate how opioid-addicted individuals learn from positive and negative feedback, and how they generalize this learning. The opioid-addicted group consisted of 33 participants with a history of heroin dependency currently in a methadone maintenance program; the control group consisted of 32 healthy participants without a history of drug addiction. All participants performed a novel variant of the acquired equivalence task, where they learned to map some stimuli to correct outcomes in order to obtain reward, and to map other stimuli to correct outcomes in order to avoid punishment; some stimuli were implicitly “equivalent” in the sense of being paired with the same outcome. On the initial training phase, both groups performed similarly on learning to obtain reward, but as memory load grew, the control group outperformed the addicted group on learning to avoid punishment. On a subsequent testing phase, the addicted and control groups performed similarly on retention trials involving previously-trained stimulus-outcome pairs, as well as on generalization trials to assess acquired equivalence. Since prior work with acquired equivalence tasks has associated stimulus-outcome learning with the nigrostriatal dopamine system, and generalization with the hippocampal region, the current results are consistent with basal ganglia dysfunction in the opioid-addicted patients. Further, a selective deficit in learning from punishment could contribute to processes by which addicted individuals continue to pursue drug use even at the cost of negative consequences such as loss of income and the opportunity to engage in other life activities. PMID:27641323

Increased conditioned pain modulation in athletes.

PubMed

Flood, Andrew; Waddington, Gordon; Thompson, Kevin; Cathcart, Stuart

2017-06-01

The potential relationship between physical activity and endogenous pain modulatory capacity remains unclear. Therefore, the aim of the current study was to compare the pain modulatory responses of athletes and non-athletes. Conditioned pain modulation (CPM) was assessed in 15 athletes and 15 non-athletes at rest. Participation was restricted to pain-free males between 18 and 40 years of age. To measure CPM capacity, a sequential CPM testing protocol was implemented, whereby a test stimulus (pressure pain threshold [PPT]) was presented before and immediately after a conditioning stimulus (4-min cold-pressor test). Pain intensity ratings were obtained at 15-s intervals throughout the cold-pressor task using a numerical rating scale. Athletes demonstrated higher baseline PPTs compared to non-athletes (P = .03). Athletes also gave lower mean (P < .001) and maximum (P < .001) pain intensity ratings in response to the conditioning stimulus. The conditioning stimulus had a stronger inhibitory effect on the test stimulus in athletes, showing enhanced CPM in athletes compared to non-athletes (P < .05). This finding of enhanced CPM in athletes helps clarify previous mixed findings. Potential implications for exercise performance and injury are discussed.

EFFICIENTLY ESTABLISHING CONCEPTS OF INFERENTIAL STATISTICS AND HYPOTHESIS DECISION MAKING THROUGH CONTEXTUALLY CONTROLLED EQUIVALENCE CLASSES

PubMed Central

Fienup, Daniel M; Critchfield, Thomas S

2010-01-01

Computerized lessons that reflect stimulus equivalence principles were used to teach college students concepts related to inferential statistics and hypothesis decision making. Lesson 1 taught participants concepts related to inferential statistics, and Lesson 2 taught them to base hypothesis decisions on a scientific hypothesis and the direction of an effect. Lesson 3 taught the conditional influence of inferential statistics over decisions regarding the scientific and null hypotheses. Participants entered the study with low scores on the targeted skills and left the study demonstrating a high level of accuracy on these skills, which involved mastering more relations than were taught formally. This study illustrates the efficiency of equivalence-based instruction in establishing academic skills in sophisticated learners. PMID:21358904

Recording evoked potentials during deep brain stimulation: development and validation of instrumentation to suppress the stimulus artefact

PubMed Central

Kent, A R; Grill, W M

2012-01-01

Deep brain stimulation (DBS) is an effective treatment for movement disorders, but the selection of stimulus parameters is a clinical burden and often yields sub-optimal outcomes for patients. Measurement of electrically evoked compound action potentials (ECAPs) during DBS could offer insight into the type and spatial extent of neural element activation and provide a potential feedback signal for the rational selection of stimulus parameters and closed-loop DBS. However, recording ECAPs presents a significant technical challenge due to the large stimulus artefact, which can saturate recording amplifiers and distort short latency ECAP signals. We developed DBS-ECAP recording instrumentation combining commercial amplifiers and circuit elements in a serial configuration to reduce the stimulus artefact and enable high fidelity recording. We used an electrical circuit equivalent model of the instrumentation to understand better the sources of the stimulus artefact and the mechanisms of artefact reduction by the circuit elements. In vitro testing validated the capability of the instrumentation to suppress the stimulus artefact and increase gain by a factor of 1,000 to 5,000 compared to a conventional biopotential amplifier. The distortion of mock ECAP (mECAP) signals was measured across stimulation parameters, and the instrumentation enabled high fidelity recording of mECAPs with latencies of only 0.5 ms for DBS pulse widths of 50 to 100 μs/phase. Subsequently, the instrumentation was used to record in vivo ECAPs, without contamination by the stimulus artefact, during thalamic DBS in an anesthetized cat. The characteristics of the physiological ECAP were dependent on stimulation parameters. The novel instrumentation enables high fidelity ECAP recording and advances the potential use of the ECAP as a feedback signal for the tuning of DBS parameters. PMID:22510375

Heterogeneity in the spatial receptive field architecture of multisensory neurons of the superior colliculus and its effects on multisensory integration

PubMed Central

Ghose, Dipanwita; Wallace, Mark T.

2013-01-01

Multisensory integration has been widely studied in neurons of the mammalian superior colliculus (SC). This has led to the description of various determinants of multisensory integration, including those based on stimulus- and neuron-specific factors. The most widely characterized of these illustrate the importance of the spatial and temporal relationships of the paired stimuli as well as their relative effectiveness in eliciting a response in determining the final integrated output. Although these stimulus-specific factors have generally been considered in isolation (i.e., manipulating stimulus location while holding all other factors constant), they have an intrinsic interdependency that has yet to be fully elucidated. For example, changes in stimulus location will likely also impact both the temporal profile of response and the effectiveness of the stimulus. The importance of better describing this interdependency is further reinforced by the fact that SC neurons have large receptive fields, and that responses at different locations within these receptive fields are far from equivalent. To address these issues, the current study was designed to examine the interdependency between the stimulus factors of space and effectiveness in dictating the multisensory responses of SC neurons. The results show that neuronal responsiveness changes dramatically with changes in stimulus location – highlighting a marked heterogeneity in the spatial receptive fields of SC neurons. More importantly, this receptive field heterogeneity played a major role in the integrative product exhibited by stimulus pairings, such that pairings at weakly responsive locations of the receptive fields resulted in the largest multisensory interactions. Together these results provide greater insight into the interrelationship of the factors underlying multisensory integration in SC neurons, and may have important mechanistic implications for multisensory integration and the role it plays in shaping SC mediated behaviors. PMID:24183964

Improving Accuracy of Portion-Size Estimations through a Stimulus Equivalence Paradigm

ERIC Educational Resources Information Center

Hausman, Nicole L.; Borrero, John C.; Fisher, Alyssa; Kahng, SungWoo

2014-01-01

The prevalence of obesity continues to increase in the United States (Gordon-Larsen, The, & Adair, 2010). Obesity can be attributed, in part, to overconsumption of energy-dense foods. Given that overeating plays a role in the development of obesity, interventions that teach individuals to identify and consume appropriate portion sizes are…

The Induction of Emergent Relations in Children with Severe Cognitive and Language Delays

ERIC Educational Resources Information Center

Howarth, Matthew

2012-01-01

In three experiments I sought to experimentally test a source of emergent relations defined as transitivity by Stimulus Equivalence theory or as combinatorial entailment in Relational Frame Theory. In Experiment I, the participants were 4 children diagnosed with autism who also demonstrated significant cognitive and language delays, who were…

Teaching Early Braille Literacy Skills within a Stimulus Equivalence Paradigm to Children with Degenerative Visual Impairments

ERIC Educational Resources Information Center

Toussaint, Karen A.; Tiger, Jeffrey H.

2010-01-01

Despite the need for braille literacy, there has been little attempt to systematically evaluate braille-instruction programs. The current study evaluated an instructive procedure for teaching early braille-reading skills with 4 school-aged children with degenerative visual impairments. Following a series of pretests, braille instruction involved…

A Relational Frame Training Intervention to Raise Intelligence Quotients: A Pilot Study

ERIC Educational Resources Information Center

Cassidy, Sarah; Roche, Bryan; Hayes, Steven C.

2011-01-01

The current research consisted of 2 studies designed to test the effectiveness of automated multiple-exemplar relational training in raising children's general intellectual skills. In Study 1, 4 participants were exposed to multiple exemplar training in stimulus equivalence and the relational frames of SAME, OPPOSITE, MORE THAN, and LESS THAN…

77 FR 9906 - Nationwide Categorical Waivers Under Section 1605 (Buy American) of the American Recovery and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-21

... (4) network manager for conversion of proprietary protocol--Staefa brand system--to a non-proprietary... conversion of proprietary protocol--Staefa brand system--to a non-proprietary open source protocol, are not... their scouting process did not locate any domestic manufacturers for these exact or equivalent items. In...

Perceptual Grouping Enhances Visual Plasticity

PubMed Central

Mastropasqua, Tommaso; Turatto, Massimo

2013-01-01

Visual perceptual learning, a manifestation of neural plasticity, refers to improvements in performance on a visual task achieved by training. Attention is known to play an important role in perceptual learning, given that the observer's discriminative ability improves only for those stimulus feature that are attended. However, the distribution of attention can be severely constrained by perceptual grouping, a process whereby the visual system organizes the initial retinal input into candidate objects. Taken together, these two pieces of evidence suggest the interesting possibility that perceptual grouping might also affect perceptual learning, either directly or via attentional mechanisms. To address this issue, we conducted two experiments. During the training phase, participants attended to the contrast of the task-relevant stimulus (oriented grating), while two similar task-irrelevant stimuli were presented in the adjacent positions. One of the two flanking stimuli was perceptually grouped with the attended stimulus as a consequence of its similar orientation (Experiment 1) or because it was part of the same perceptual object (Experiment 2). A test phase followed the training phase at each location. Compared to the task-irrelevant no-grouping stimulus, orientation discrimination improved at the attended location. Critically, a perceptual learning effect equivalent to the one observed for the attended location also emerged for the task-irrelevant grouping stimulus, indicating that perceptual grouping induced a transfer of learning to the stimulus (or feature) being perceptually grouped with the task-relevant one. Our findings indicate that no voluntary effort to direct attention to the grouping stimulus or feature is necessary to enhance visual plasticity. PMID:23301100

Acute Physiological Responses to Strongman Training Compared to Traditional Strength Training.

PubMed

Harris, Nigel K; Woulfe, Colm J; Wood, Matthew R; Dulson, Deborah K; Gluchowski, Ashley K; Keogh, Justin B

2016-05-01

Strongman training (ST) has become an increasingly popular modality, but data on physiological responses are limited. This study sought to determine physiological responses to an ST session compared to a traditional strength exercise training (RST) session. Ten healthy men (23.6 ± 27.5 years, 85.8 ± 10.3 kg) volunteered in a crossover design, where all participants performed an ST session, an RST session, and a resting session within 7 days apart. The ST consisted of sled drag, farmer's walk, 1 arm dumbbell clean and press, and tire flip at loads eliciting approximately 30 seconds of near maximal effort per set. The RST consisted of squat, deadlift, bench press, and power clean, progressing to 75% of 1 repetition maximum. Sessions were equated for approximate total set duration. Blood lactate and salivary testosterone were recorded immediately before and after training sessions. Heart rate, caloric expenditure, and substrate utilization were measured throughout the resting session, both training protocols and for 80 minutes after training sessions. Analyses were conducted to determine differences in physiological responses within and between protocols. No significant changes in testosterone occurred at any time point for either session. Lactate increased significantly immediately after both sessions. Heart rate, caloric expenditure, and substrate utilization were all elevated significantly during ST and RST. Heart rate and fat expenditure were significantly elevated compared to resting in both sessions' recovery periods; calorie and carbohydrate expenditures were not. Compared to RST, ST represents an equivalent physiological stimulus on key parameters indicative of potential training-induced adaptive responses. Such adaptations could conceivably include cardiovascular conditioning.

Effect of reading on blood flow changes in the posterior cerebral artery in early blind and sighted people--A transcranial Doppler study.

PubMed

Viski, Sandor; Orgovan, David; Szabo, Katalin; Rosengarten, Bernhard; Csiba, Laszlo; Olah, Laszlo

2016-04-15

Neuroimaging studies proved that Braille reading resulted in visual cortex activation in blind people, however, very few data are available about the measure of flow increase in these subjects. Therefore, we investigated the flow response in the posterior cerebral artery (PCA) of eleven early blind and ten sighted subjects induced by reading Braille and print, respectively. Two experimental protocols were used in both groups: PCA flow velocity during reading was compared to the resting phase and "NLC" phase (volunteers "read" non-lexical characters; e.g. .,-.:,-.:...,). The use of these experimental protocols allowed to investigate separately the effect of "light stimulus+print reading" versus "print reading alone" in sighted, and "hand/finger movement+Braille reading" versus "Braille reading alone" in blind subjects. The flow response in the PCA evoked by "Braille reading alone" in blind (10.5±4.5%) and "print reading alone" in sighted subjects (8.1±3.5%) was similar. The flow increase induced by "hand/finger movement+Braille reading" and by "Braille reading alone" did not differ in blind people, however, "light stimulus+print reading" in sighted subjects caused higher PCA flow increase (25.9±6.9%) than "print reading alone" (8.1±3.5%). The similar PCA flow response induced by Braille and print reading alone suggested a similar degree of occipital cortex activation in blind and sighted subjects. In sighted people, the 3-times higher flow velocity increase induced by "light stimulus+print reading" compared with "print reading alone" indicated that 2/3 of PCA flow increase during reading was due to the light stimulus and only 1/3 of flow response was caused by reading alone. Copyright © 2016 Elsevier B.V. All rights reserved.

Can a single pulse transcranial magnetic stimulation targeted to the motor cortex interrupt pain processing?

PubMed Central

Kisler, Lee-Bareket; Gurion, Ilan; Granovsky, Yelena; Sinai, Alon; Sprecher, Elliot; Shamay-Tsoory, Simone

2018-01-01

The modulatory role of the primary motor cortex (M1), reflected by an inhibitory effect of M1-stimulation on clinical pain, motivated us to deepen our understanding of M1’s role in pain modulation. We used Transcranial Magnetic Stimulation (TMS)-induced virtual lesion (VL) to interrupt with M1 activity during noxious heat pain. We hypothesized that TMS-VL will effect experimental pain ratings. Three VL protocols were applied consisting of single-pulse TMS to transiently interfere with right M1 activity: (1) VLM1- TMS applied to 11 subjects, 20 msec before the individual’s first pain-related M1 peak activation, as determined by source analysis (sLORETA), (2) VL-50 (N = 16; TMS applied 50 ms prior to noxious stimulus onset), and (3) VL+150 (N = 16; TMS applied 150 ms after noxious stimulus onset). Each protocol included 3 conditions ('pain-alone', ' TMS-VL', and ‘SHAM-VL’), each consisted of 30 noxious heat stimuli. Pain ratings were compared, in each protocol, for TMS-VL vs. SHAM-VL and vs. pain-alone conditions. Repeated measures analysis of variance, corrected for multiple comparisons revealed no significant differences in the pain ratings between the different conditions within each protocol. Therefore, our results from this exploratory study suggest that a single pulse TMS-induced VL that is targeted to M1 failed to interrupt experimental pain processing in the specific three stimulation timing examined here. PMID:29630681

Can a single pulse transcranial magnetic stimulation targeted to the motor cortex interrupt pain processing?

PubMed

Kisler, Lee-Bareket; Gurion, Ilan; Granovsky, Yelena; Sinai, Alon; Sprecher, Elliot; Shamay-Tsoory, Simone; Weissman-Fogel, Irit

2018-01-01

The modulatory role of the primary motor cortex (M1), reflected by an inhibitory effect of M1-stimulation on clinical pain, motivated us to deepen our understanding of M1's role in pain modulation. We used Transcranial Magnetic Stimulation (TMS)-induced virtual lesion (VL) to interrupt with M1 activity during noxious heat pain. We hypothesized that TMS-VL will effect experimental pain ratings. Three VL protocols were applied consisting of single-pulse TMS to transiently interfere with right M1 activity: (1) VLM1- TMS applied to 11 subjects, 20 msec before the individual's first pain-related M1 peak activation, as determined by source analysis (sLORETA), (2) VL-50 (N = 16; TMS applied 50 ms prior to noxious stimulus onset), and (3) VL+150 (N = 16; TMS applied 150 ms after noxious stimulus onset). Each protocol included 3 conditions ('pain-alone', ' TMS-VL', and 'SHAM-VL'), each consisted of 30 noxious heat stimuli. Pain ratings were compared, in each protocol, for TMS-VL vs. SHAM-VL and vs. pain-alone conditions. Repeated measures analysis of variance, corrected for multiple comparisons revealed no significant differences in the pain ratings between the different conditions within each protocol. Therefore, our results from this exploratory study suggest that a single pulse TMS-induced VL that is targeted to M1 failed to interrupt experimental pain processing in the specific three stimulation timing examined here.

Extinction training during the reconsolidation window prevents recovery of fear.

PubMed

Schiller, Daniela; Raio, Candace M; Phelps, Elizabeth A

2012-08-24

Fear is maladaptive when it persists long after circumstances have become safe. It is therefore crucial to develop an approach that persistently prevents the return of fear. Pavlovian fear-conditioning paradigms are commonly employed to create a controlled, novel fear association in the laboratory. After pairing an innocuous stimulus (conditioned stimulus, CS) with an aversive outcome (unconditioned stimulus, US) we can elicit a fear response (conditioned response, or CR) by presenting just the stimulus alone. Once fear is acquired, it can be diminished using extinction training, whereby the conditioned stimulus is repeatedly presented without the aversive outcome until fear is no longer expressed. This inhibitory learning creates a new, safe representation for the CS, which competes for expression with the original fear memory. Although extinction is effective at inhibiting fear, it is not permanent. Fear can spontaneously recover with the passage of time. Exposure to stress or returning to the context of initial learning can also cause fear to resurface. Our protocol addresses the transient nature of extinction by targeting the reconsolidation window to modify emotional memory in a more permanent manner. Ample evidence suggests that reactivating a consolidated memory returns it to a labile state, during which the memory is again susceptible to interference. This window of opportunity appears to open shortly after reactivation and close approximately 6 hrs later, although this may vary depending on the strength and age of the memory. By allowing new information to incorporate into the original memory trace, this memory may be updated as it reconsolidates. Studies involving non-human animals have successfully blocked the expression of fear memory by introducing pharmacological manipulations within the reconsolidation window, however, most agents used are either toxic to humans or show equivocal effects when used in human studies. Our protocol addresses these challenges by offering an effective, yet non-invasive, behavioral manipulation that is safe for humans. By prompting fear memory retrieval prior to extinction, we essentially trigger the reconsolidation process, allowing new safety information (i.e., extinction) to be incorporated while the fear memory is still susceptible to interference. A recent study employing this behavioral manipulation in rats has successfully blocked fear memory using these temporal parameters. Additional studies in humans have demonstrated that introducing new information after the retrieval of previously consolidated motor, episodic, or declarative memories leads to interference with the original memory trace. We outline below a novel protocol used to block fear recovery in humans.

Coagulation changes during lower body negative pressure and blood loss in humans.

PubMed

van Helmond, Noud; Johnson, Blair D; Curry, Timothy B; Cap, Andrew P; Convertino, Victor A; Joyner, Michael J

2015-11-01

We tested the hypothesis that markers of coagulation activation are greater during lower body negative pressure (LBNP) than those obtained during blood loss (BL). We assessed coagulation using both standard clinical tests and thrombelastography (TEG) in 12 men who performed a LBNP and BL protocol in a randomized order. LBNP consisted of 5-min stages at 0, -15, -30, and -45 mmHg of suction. BL included 5 min at baseline and following three stages of 333 ml of blood removal (up to 1,000 ml total). Arterial blood draws were performed at baseline and after the last stage of each protocol. We found that LBNP to -45 mmHg is a greater central hypovolemic stimulus versus BL; therefore, the coagulation markers were plotted against central venous pressure (CVP) to obtain stimulus-response relationships using the linear regression line slopes for both protocols. Paired t-tests were used to determine whether the slopes of these regression lines fell on similar trajectories for each protocol. Mean regression line slopes for coagulation markers versus CVP fell on similar trajectories during both protocols, except for TEG α° angle (-0.42 ± 0.96 during LBNP vs. -2.41 ± 1.13°/mmHg during BL; P < 0.05). During both LBNP and BL, coagulation was accelerated as evidenced by shortened R-times (LBNP, 9.9 ± 2.4 to 6.2 ± 1.1; BL, 8.7 ± 1.3 to 6.4 ± 0.4 min; both P < 0.05). Our results indicate that LBNP models the general changes in coagulation markers observed during BL. Copyright © 2015 the American Physiological Society.

The effect of stimulus strength on binocular rivalry rate in healthy individuals: Implications for genetic, clinical and individual differences studies.

PubMed

Law, Phillip C F; Miller, Steven M; Ngo, Trung T

2017-11-01

Binocular rivalry (BR) occurs when conflicting images concurrently presented to corresponding retinal locations of each eye stochastically alternate in perception. Anomalies of BR rate have been examined in a range of clinical psychiatric conditions. In particular, slow BR rate has been proposed as an endophenotype for bipolar disorder (BD) to improve power in large-scale genome-wide association studies. Examining the validity of BR rate as a BD endophenotype however requires large-scale datasets (n=1000s to 10,000s), a standardized testing protocol, and optimization of stimulus parameters to maximize separation between BD and healthy groups. Such requirements are indeed relevant to all clinical psychiatric BR studies. Here we address the issue of stimulus optimization by examining the effect of stimulus parameter variation on BR rate and mixed-percept duration (MPD) in healthy individuals. We aimed to identify the stimulus parameters that induced the fastest BR rates with the least MPD. Employing a repeated-measures within-subjects design, 40 healthy adults completed four BR tasks using orthogonally drifting grating stimuli that varied in drift speed and aperture size. Pairwise comparisons were performed to determine modulation of BR rate and MPD by these stimulus parameters, and individual variation of such modulation was also assessed. From amongst the stimulus parameters examined, we found that 8cycles/s drift speed in a 1.5° aperture induced the fastest BR rate without increasing MPD, but that BR rate with this stimulus configuration was not substantially different to BR rate with stimulus parameters we have used in previous studies (i.e., 4cycles/s drift speed in a 1.5° aperture). In addition to contributing to stimulus optimization issues, the findings have implications for Levelt's Proposition IV of binocular rivalry dynamics and individual differences in such dynamics. Copyright © 2017 Elsevier Inc. All rights reserved.

An electroejaculator for the collection of semen from the domestic cat.

PubMed

Dooley, M P; Murase, K; Pineda, M H

1983-09-01

An electroejaculator for the collection of cat semen and for the evaluation of electroejaculation protocols is described. The electroejaculator contains an adjustable signal generator and allows for the precise control and monitoring of the electrical stimulus to the animal. The electroejaculator incorporates controls for the selection of the frequency, potential and waveform of the electrical stimulus and controls for either manual or automatic delivery of stimuli of specified characteristics to the rectal probe. In the automatic mode, the operator may also preset the rate and duration of stimulus application and the interval between successive stimuli. The electroejaculator output to the probe is controlled with an on-off foot-switch which allows for the collection of semen from an anesthetized cat by one operator. Diagrams of the functional block, the component circuits of the electroejaculator, and the accessories which facilitate the collection of cat semen are provided.

[Generalization of money-handling though training in equivalence relationships].

PubMed

Vives-Montero, Carmen; Valero-Aguayo, Luis; Ascanio, Lourdes

2011-02-01

This research used a matching-to-sample procedure and equivalence learning process with language and verbal tasks. In the study, an application of the equivalence relationship of money was used with several kinds of euro coins presented. The sample consisted of 16 children (8 in the experimental group and 8 in the control group) aged 5 years. The prerequisite behaviors, the identification of coins and the practical use of different euro coins, were assessed in the pre and post phases for both groups. The children in the experimental group performed an equivalence task using the matching-to-sample procedure. This consisted of a stimulus sample and four matching stimuli, using a series of euro coins with equivalent value in each set. The children in the control group did not undergo this training process. The results showed a large variability in the children's data of the equivalence tests. The experimental group showed the greatest pre and post changes in the statistically significant data. They also showed a greater generalization in the identification of money and in the use of euro coins than the control group. The implications for educational training and the characteristics of the procedure used here for coin equivalence are discussed.

Conditional Discriminations by Preverbal Children in an Identity Matching-to-Sample Task

ERIC Educational Resources Information Center

de Alcantara Gil, Maria Stella C.; de Oliveira, Thais Porlan; McIlvane, William J.

2011-01-01

This study sought to develop methodology for assessing whether children ages 16-21 months could learn to match stimuli on the basis of physical identity in conditional discrimination procedures routinely used in stimulus equivalence research with older participants. The study was conducted in a private room at a day-care center for children and…

Relational Discrimination by Pigeons in a Go/No-Go Procedure with Compound Stimuli: A Methodological Note

ERIC Educational Resources Information Center

Campos, Heloisa Cursi; Debert, Paula; Barros, Romariz da Silva; McIlvane, William J.

2011-01-01

A go/no-go procedure with compound stimuli typically establishes emergent behavior that parallels in structure and typical outcome that of conventional tests for symmetric, transitive, and equivalence relations in normally capable adults. The present study employed a go/no-go compound stimulus procedure with pigeons. During training, pecks to…

Involvement of phosphorylated Apis mellifera CREB in gating a honeybee's behavioral response to an external stimulus

PubMed Central

Gehring, Katrin B.; Heufelder, Karin; Feige, Janina; Bauer, Paul; Dyck, Yan; Ehrhardt, Lea; Kühnemund, Johannes; Bergmann, Anja; Göbel, Josefine; Isecke, Marlene

2016-01-01

The transcription factor cAMP-response element-binding protein (CREB) is involved in neuronal plasticity. Phosphorylation activates CREB and an increased level of phosphorylated CREB is regarded as an indicator of CREB-dependent transcriptional activation. In honeybees (Apis mellifera) we recently demonstrated a particular high abundance of the phosphorylated honeybee CREB homolog (pAmCREB) in the central brain and in a subpopulation of mushroom body neurons. We hypothesize that these high pAmCREB levels are related to learning and memory formation. Here, we tested this hypothesis by analyzing brain pAmCREB levels in classically conditioned bees and bees experiencing unpaired presentations of conditioned stimulus (CS) and unconditioned stimulus (US). We demonstrate that both behavioral protocols display differences in memory formation but do not alter the level of pAmCREB in bee brains directly after training. Nevertheless, we report that bees responding to the CS during unpaired stimulus presentations exhibit higher levels of pAmCREB than nonresponding bees. In addition, Trichostatin A, a histone deacetylase inhibitor that is thought to enhance histone acetylation by CREB-binding protein, increases the bees’ CS responsiveness. We conclude that pAmCREB is involved in gating a bee's behavioral response driven by an external stimulus. PMID:27084927

StimDuino: an Arduino-based electrophysiological stimulus isolator.

PubMed

Sheinin, Anton; Lavi, Ayal; Michaelevski, Izhak

2015-03-30

Electrical stimulus isolator is a widely used device in electrophysiology. The timing of the stimulus application is usually automated and controlled by the external device or acquisition software; however, the intensity of the stimulus is adjusted manually. Inaccuracy, lack of reproducibility and no automation of the experimental protocol are disadvantages of the manual adjustment. To overcome these shortcomings, we developed StimDuino, an inexpensive Arduino-controlled stimulus isolator allowing highly accurate, reproducible automated setting of the stimulation current. The intensity of the stimulation current delivered by StimDuino is controlled by Arduino, an open-source microcontroller development platform. The automatic stimulation patterns are software-controlled and the parameters are set from Matlab-coded simple, intuitive and user-friendly graphical user interface. The software also allows remote control of the device over the network. Electrical current measurements showed that StimDuino produces the requested current output with high accuracy. In both hippocampal slice and in vivo recordings, the fEPSP measurements obtained with StimDuino and the commercial stimulus isolators showed high correlation. Commercial stimulus isolators are manually managed, while StimDuino generates automatic stimulation patterns with increasing current intensity. The pattern is utilized for the input-output relationship analysis, necessary for assessment of excitability. In contrast to StimuDuino, not all commercial devices are capable for remote control of the parameters and stimulation process. StimDuino-generated automation of the input-output relationship assessment eliminates need for the current intensity manually adjusting, improves stimulation reproducibility, accuracy and allows on-site and remote control of the stimulation parameters. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of Frequency and Motion Paradigm on Perception of Tilt and Translation During Periodic Linear Acceleration

NASA Technical Reports Server (NTRS)

Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, Scott J.

2009-01-01

Previous studies have demonstrated an effect of frequency on the gain of tilt and translation perception. Results from different motion paradigms are often combined to extend the stimulus frequency range. For example, Off-Vertical Axis Rotation (OVAR) and Variable Radius Centrifugation (VRC) are useful to test low frequencies of linear acceleration at amplitudes that would require impractical sled lengths. The purpose of this study was to compare roll-tilt and lateral translation motion perception in 12 healthy subjects across four paradigms: OVAR, VRC, sled translation and rotation about an earth-horizontal axis. Subjects were oscillated in darkness at six frequencies from 0.01875 to 0.6 Hz (peak acceleration equivalent to 10 deg, less for sled motion below 0.15 Hz). Subjects verbally described the amplitude of perceived tilt and translation, and used a joystick to indicate the direction of motion. Consistent with previous reports, tilt perception gain decreased as a function of stimulus frequency in the motion paradigms without concordant canal tilt cues (OVAR, VRC and Sled). Translation perception gain was negligible at low stimulus frequencies and increased at higher frequencies. There were no significant differences between the phase of tilt and translation, nor did the phase significantly vary across stimulus frequency. There were differences in perception gain across the different paradigms. Paradigms that included actual tilt stimuli had the larger tilt gains, and paradigms that included actual translation stimuli had larger translation gains. In addition, the frequency at which there was a crossover of tilt and translation gains appeared to vary across motion paradigm between 0.15 and 0.3 Hz. Since the linear acceleration in the head lateral plane was equivalent across paradigms, differences in gain may be attributable to the presence of linear accelerations in orthogonal directions and/or cognitive aspects based on the expected motion paths.

Conditional discriminations, symmetry, and semantic priming.

PubMed

Vaidya, Manish; Hudgins, Caleb D; Ortu, Daniele

2015-09-01

Psychologists interested in the study of symbolic behavior have found that people are faster at reporting that two words are related to one another than they are in reporting that two words are not related - an effect called semantic priming. This phenomenon has largely been documented in the context of natural languages using real words as stimuli. The current study asked whether laboratory-generated stimulus-stimulus relations established between arbitrary geometrical shapes would also show the semantic priming effect. Participants learned six conditional relations using a one-to-many training structure (A1-B1, A1-C1, A1-D1, A2-B2, A2-C2, A2-D2) and demonstrated, via accurate performance on tests of derived symmetry, that the trained stimulus functions had become reversible. In a lexical decision task, subjects also demonstrated a priming effect as they displayed faster reaction times to target stimuli when the prime and target came from the same trained or derived conditional relations, compared to the condition in which the prime and target came from different trained or derived conditional relations. These data suggest that laboratory-generated equivalence relations may serve as useful analogues of symbolic behavior. However, the fact that conditional relations training and symmetry alone were sufficient to produce the effect suggests that semantic priming like effects may be the byproduct of simpler stimulus-stimulus relations. Copyright © 2015 Elsevier B.V. All rights reserved.

Security of counterfactual quantum cryptography

NASA Astrophysics Data System (ADS)

Yin, Zhen-Qiang; Li, Hong-Wei; Chen, Wei; Han, Zheng-Fu; Guo, Guang-Can

2010-10-01

Recently, a “counterfactual” quantum-key-distribution scheme was proposed by T.-G. Noh [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.230501 103, 230501 (2009)]. In this scheme, two legitimate distant peers may share secret keys even when the information carriers are not traveled in the quantum channel. We find that this protocol is equivalent to an entanglement distillation protocol. According to this equivalence, a strict security proof and the asymptotic key bit rate are both obtained when a perfect single-photon source is applied and a Trojan horse attack can be detected. We also find that the security of this scheme is strongly related to not only the bit error rate but also the yields of photons. And our security proof may shed light on the security of other two-way protocols.

Security of counterfactual quantum cryptography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin Zhenqiang; Li Hongwei; Chen Wei

2010-10-15

Recently, a 'counterfactual' quantum-key-distribution scheme was proposed by T.-G. Noh [Phys. Rev. Lett. 103, 230501 (2009)]. In this scheme, two legitimate distant peers may share secret keys even when the information carriers are not traveled in the quantum channel. We find that this protocol is equivalent to an entanglement distillation protocol. According to this equivalence, a strict security proof and the asymptotic key bit rate are both obtained when a perfect single-photon source is applied and a Trojan horse attack can be detected. We also find that the security of this scheme is strongly related to not only the bitmore » error rate but also the yields of photons. And our security proof may shed light on the security of other two-way protocols.« less

Humans treat unreliable filled-in percepts as more real than veridical ones

PubMed Central

Ehinger, Benedikt V; Häusser, Katja; Ossandón, José P; König, Peter

2017-01-01

Humans often evaluate sensory signals according to their reliability for optimal decision-making. However, how do we evaluate percepts generated in the absence of direct input that are, therefore, completely unreliable? Here, we utilize the phenomenon of filling-in occurring at the physiological blind-spots to compare partially inferred and veridical percepts. Subjects chose between stimuli that elicit filling-in, and perceptually equivalent ones presented outside the blind-spots, looking for a Gabor stimulus without a small orthogonal inset. In ambiguous conditions, when the stimuli were physically identical and the inset was absent in both, subjects behaved opposite to optimal, preferring the blind-spot stimulus as the better example of a collinear stimulus, even though no relevant veridical information was available. Thus, a percept that is partially inferred is paradoxically considered more reliable than a percept based on external input. In other words: Humans treat filled-in inferred percepts as more real than veridical ones. DOI: http://dx.doi.org/10.7554/eLife.21761.001 PMID:28506359

Estimating linear-nonlinear models using Rényi divergences

PubMed Central

Kouh, Minjoon; Sharpee, Tatyana O.

2009-01-01

This paper compares a family of methods for characterizing neural feature selectivity using natural stimuli in the framework of the linear-nonlinear model. In this model, the spike probability depends in a nonlinear way on a small number of stimulus dimensions. The relevant stimulus dimensions can be found by optimizing a Rényi divergence that quantifies a change in the stimulus distribution associated with the arrival of single spikes. Generally, good reconstructions can be obtained based on optimization of Rényi divergence of any order, even in the limit of small numbers of spikes. However, the smallest error is obtained when the Rényi divergence of order 1 is optimized. This type of optimization is equivalent to information maximization, and is shown to saturate the Cramér-Rao bound describing the smallest error allowed for any unbiased method. We also discuss conditions under which information maximization provides a convenient way to perform maximum likelihood estimation of linear-nonlinear models from neural data. PMID:19568981

Estimating linear-nonlinear models using Renyi divergences.

PubMed

Kouh, Minjoon; Sharpee, Tatyana O

2009-01-01

This article compares a family of methods for characterizing neural feature selectivity using natural stimuli in the framework of the linear-nonlinear model. In this model, the spike probability depends in a nonlinear way on a small number of stimulus dimensions. The relevant stimulus dimensions can be found by optimizing a Rényi divergence that quantifies a change in the stimulus distribution associated with the arrival of single spikes. Generally, good reconstructions can be obtained based on optimization of Rényi divergence of any order, even in the limit of small numbers of spikes. However, the smallest error is obtained when the Rényi divergence of order 1 is optimized. This type of optimization is equivalent to information maximization, and is shown to saturate the Cramer-Rao bound describing the smallest error allowed for any unbiased method. We also discuss conditions under which information maximization provides a convenient way to perform maximum likelihood estimation of linear-nonlinear models from neural data.

Measurement of hearing aid internal noise1

PubMed Central

Lewis, James D.; Goodman, Shawn S.; Bentler, Ruth A.

2010-01-01

Hearing aid equivalent input noise (EIN) measures assume the primary source of internal noise to be located prior to amplification and to be constant regardless of input level. EIN will underestimate internal noise in the case that noise is generated following amplification. The present study investigated the internal noise levels of six hearing aids (HAs). Concurrent with HA processing of a speech-like stimulus with both adaptive features (acoustic feedback cancellation, digital noise reduction, microphone directionality) enabled and disabled, internal noise was quantified for various stimulus levels as the variance across repeated trials. Changes in noise level as a function of stimulus level demonstrated that (1) generation of internal noise is not isolated to the microphone, (2) noise may be dependent on input level, and (3) certain adaptive features may contribute to internal noise. Quantifying internal noise as the variance of the output measures allows for noise to be measured under real-world processing conditions, accounts for all sources of noise, and is predictive of internal noise audibility. PMID:20370034

Quality, efficiency, and cost of a physician-assistant-protocol system for managment of diabetes and hypertension.

PubMed

Komaroff, A L; Flatley, M; Browne, C; Sherman, H; Fineberg, S E; Knopp, R H

1976-04-01

Briefly trained physicians assistants using protocols (clinical algorithms) for diabetes, hypertension, and related chronic arteriosclerotic and hypertensive heart disease abstrated information from the medical record and obtained history and physical examination data on every patient-visit to a city hospital chronic disease clinic over a 18-month period. The care rendered by the protocol system was compared with care rendered by a "traditional" system in the same clinic in which physicians delegated few clinical tasks. Increased thoroughness in collecting clinical data in the protocol system led to an increase in the recognition of new pathology. Outcome criteria reflected equivalent quality of care in both groups. Efficiency time-motion studies demonstrated a 20 per cent saving in physician time with the protocol system. Coct estimates, based on the time spent with patients by various providers and on the laboratory-test-ordering patterns, demonstrated equivalent costs of the two systems, given optimal staffing patterns. Laboratory tests were a major element of the cost of patient care,and the clinical yield per unit cost of different tests varied widely.

Bidirectional Telemetry Controller for Neuroprosthetic Devices

PubMed Central

Sharma, Vishnu; McCreery, Douglas B.; Han, Martin; Pikov, Victor

2010-01-01

We present versatile multifunctional programmable controller with bidirectional data telemetry, implemented using existing commercial microchips and standard Bluetooth protocol, which adds convenience, reliability, and ease-of-use to neuroprosthetic devices. Controller, weighing 190 g, is placed on animal's back and provides bidirectional sustained telemetry rate of 500 kb/s, allowing real-time control of stimulation parameters and viewing of acquired data. In continuously-active state, controller consumes ∼420 mW and operates without recharge for 8 h. It features independent 16-channel current-controlled stimulation, allowing current steering; customizable stimulus current waveforms; recording of stimulus voltage waveforms and evoked neuronal responses with stimulus artifact blanking circuitry. Flexibility, scalability, cost-efficiency, and a user-friendly computer interface of this device allow use in animal testing for variety of neuroprosthetic applications. Initial testing of the controller has been done in a feline model of brainstem auditory prosthesis. In this model, the electrical stimulation is applied to the array of microelectrodes implanted in the ventral cochlear nucleus, while the evoked neuronal activity was recorded with the electrode implanted in the contralateral inferior colliculus. Stimulus voltage waveforms to monitor the access impedance of the electrodes were acquired at the rate of 312 kilosamples/s. Evoked neuronal activity in the inferior colliculus was recorded after the blanking (transient silencing) of the recording amplifier during the stimulus pulse, allowing the detection of neuronal responses within 100 μs after the end of the stimulus pulse applied in the cochlear nucleus. PMID:19933010

TEACHING EARLY BRAILLE LITERACY SKILLS WITHIN A STIMULUS EQUIVALENCE PARADIGM TO CHILDREN WITH DEGENERATIVE VISUAL IMPAIRMENTS

PubMed Central

Toussaint, Karen A; Tiger, Jeffrey H

2010-01-01

Despite the need for braille literacy, there has been little attempt to systematically evaluate braille-instruction programs. The current study evaluated an instructive procedure for teaching early braille-reading skills with 4 school-aged children with degenerative visual impairments. Following a series of pretests, braille instruction involved providing a sample braille letter and teaching the selection of the corresponding printed letter from a comparison array. Concomitant with increases in the accuracy of this skill, we assessed and captured the formation of equivalence classes through tests of symmetry and transitivity among the printed letters, the corresponding braille letters, and their spoken names. PMID:21119894

Teaching early braille literacy skills within a stimulus equivalence paradigm to children with degenerative visual impairments.

PubMed

Toussaint, Karen A; Tiger, Jeffrey H

2010-01-01

Despite the need for braille literacy, there has been little attempt to systematically evaluate braille-instruction programs. The current study evaluated an instructive procedure for teaching early braille-reading skills with 4 school-aged children with degenerative visual impairments. Following a series of pretests, braille instruction involved providing a sample braille letter and teaching the selection of the corresponding printed letter from a comparison array. Concomitant with increases in the accuracy of this skill, we assessed and captured the formation of equivalence classes through tests of symmetry and transitivity among the printed letters, the corresponding braille letters, and their spoken names.

Algorithmic analysis of relational learning processes in instructional technology: Some implications for basic, translational, and applied research.

PubMed

McIlvane, William J; Kledaras, Joanne B; Gerard, Christophe J; Wilde, Lorin; Smelson, David

2018-07-01

A few noteworthy exceptions notwithstanding, quantitative analyses of relational learning are most often simple descriptive measures of study outcomes. For example, studies of stimulus equivalence have made much progress using measures such as percentage consistent with equivalence relations, discrimination ratio, and response latency. Although procedures may have ad hoc variations, they remain fairly similar across studies. Comparison studies of training variables that lead to different outcomes are few. Yet to be developed are tools designed specifically for dynamic and/or parametric analyses of relational learning processes. This paper will focus on recent studies to develop (1) quality computer-based programmed instruction for supporting relational learning in children with autism spectrum disorders and intellectual disabilities and (2) formal algorithms that permit ongoing, dynamic assessment of learner performance and procedure changes to optimize instructional efficacy and efficiency. Because these algorithms have a strong basis in evidence and in theories of stimulus control, they may have utility also for basic and translational research. We present an overview of the research program, details of algorithm features, and summary results that illustrate their possible benefits. It also presents arguments that such algorithm development may encourage parametric research, help in integrating new research findings, and support in-depth quantitative analyses of stimulus control processes in relational learning. Such algorithms may also serve to model control of basic behavioral processes that is important to the design of effective programmed instruction for human learners with and without functional disabilities. Copyright © 2018 Elsevier B.V. All rights reserved.

Aversive Olfactory Learning and Associative Long-Term Memory in "Caenorhabditis elegans"

ERIC Educational Resources Information Center

Amano, Hisayuki; Maruyama, Ichiro N.

2011-01-01

The nematode "Caenorhabditis elegans" ("C. elegans") adult hermaphrodite has 302 invariant neurons and is suited for cellular and molecular studies on complex behaviors including learning and memory. Here, we have developed protocols for classical conditioning of worms with 1-propanol, as a conditioned stimulus (CS), and hydrochloride (HCl) (pH…

Mechanical sensitivity of Piezo1 ion channels can be tuned by cellular membrane tension

PubMed Central

Lewis, Amanda H; Grandl, Jörg

2015-01-01

Piezo1 ion channels mediate the conversion of mechanical forces into electrical signals and are critical for responsiveness to touch in metazoans. The apparent mechanical sensitivity of Piezo1 varies substantially across cellular environments, stimulating methods and protocols, raising the fundamental questions of what precise physical stimulus activates the channel and how its stimulus sensitivity is regulated. Here, we measured Piezo1 currents evoked by membrane stretch in three patch configurations, while simultaneously visualizing and measuring membrane geometry. Building on this approach, we developed protocols to minimize resting membrane curvature and tension prior to probing Piezo1 activity. We find that Piezo1 responds to lateral membrane tension with exquisite sensitivity as compared to other mechanically activated channels and that resting tension can drive channel inactivation, thereby tuning overall mechanical sensitivity of Piezo1. Our results explain how Piezo1 can function efficiently and with adaptable sensitivity as a sensor of mechanical stimulation in diverse cellular contexts. DOI: http://dx.doi.org/10.7554/eLife.12088.001 PMID:26646186

Teaching Manual Signs to Adults with Mental Retardation Using Matching-to-Sample Procedures and Stimulus Equivalence

ERIC Educational Resources Information Center

Elias, N. C.; Goyos, C.; Saunders, M.; Saunders, R.

2008-01-01

The objective of this study was to teach manual signs through an automated matching-to-sample procedure and to test for the emergence of new conditional relations and imitative behaviors. Seven adults with mild to severe mental retardation participated. Four were also hearing impaired. Relations between manual signs (set A) and pictures (set B)…

Learning to recognize letters in the periphery: Effects of repeated exposure, letter frequency, and letter complexity

PubMed Central

Husk, Jesse S.; Yu, Deyue

2017-01-01

Patients with central vision loss must rely on their peripheral vision for reading. Unfortunately, limitations of peripheral vision, such as crowding, pose significant challenges to letter recognition. As a result, there is a need for developing effective training methods for improving crowded letter recognition in the periphery. Several studies have shown that extensive practice with letter stimuli is beneficial to peripheral letter recognition. Here, we explore stimulus-related factors that might influence the effectiveness of peripheral letter recognition training. Specifically, we examined letter exposure (number of letter occurrences), frequency of letter use in English print, and letter complexity and evaluated their contributions to the amount of improvement observed in crowded letter recognition following training. We analyzed data collected across a range of training protocols. Using linear regression, we identified the best-fitting model and observed that all three stimulus-related factors contributed to improvement in peripheral letter recognition with letter exposure being the most important factor. As an important explanatory variable, pretest accuracy was included in the model as well to avoid estimate biases and was shown to have influence on the relationship between training improvement and letter exposure. When developing training protocols for peripheral letter recognition, it may be beneficial to not only consider the overall length of training, but also to tailor the number of stimulus occurrences for each letter according to its initial performance level, frequency, and complexity. PMID:28265651

Heterogeneity in the spatial receptive field architecture of multisensory neurons of the superior colliculus and its effects on multisensory integration.

PubMed

Ghose, D; Wallace, M T

2014-01-03

Multisensory integration has been widely studied in neurons of the mammalian superior colliculus (SC). This has led to the description of various determinants of multisensory integration, including those based on stimulus- and neuron-specific factors. The most widely characterized of these illustrate the importance of the spatial and temporal relationships of the paired stimuli as well as their relative effectiveness in eliciting a response in determining the final integrated output. Although these stimulus-specific factors have generally been considered in isolation (i.e., manipulating stimulus location while holding all other factors constant), they have an intrinsic interdependency that has yet to be fully elucidated. For example, changes in stimulus location will likely also impact both the temporal profile of response and the effectiveness of the stimulus. The importance of better describing this interdependency is further reinforced by the fact that SC neurons have large receptive fields, and that responses at different locations within these receptive fields are far from equivalent. To address these issues, the current study was designed to examine the interdependency between the stimulus factors of space and effectiveness in dictating the multisensory responses of SC neurons. The results show that neuronal responsiveness changes dramatically with changes in stimulus location - highlighting a marked heterogeneity in the spatial receptive fields of SC neurons. More importantly, this receptive field heterogeneity played a major role in the integrative product exhibited by stimulus pairings, such that pairings at weakly responsive locations of the receptive fields resulted in the largest multisensory interactions. Together these results provide greater insight into the interrelationship of the factors underlying multisensory integration in SC neurons, and may have important mechanistic implications for multisensory integration and the role it plays in shaping SC-mediated behaviors. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Extended Theories of Gravitation. Observation Protocols and Experimental Tests

NASA Astrophysics Data System (ADS)

Fatibene, Lorenzo; Ferraris, Marco; Francaviglia, Mauro; Magnano, Guido

2013-09-01

Within the framework of extended theories of gravitation we shall discuss physical equivalences among different formalisms and classical tests. As suggested by the Ehlers-Pirani-Schild framework, the conformal invariance will be preserved and its effect on observational protocols discussed. Accordingly, we shall review standard tests showing how Palatini f(R)-theories naturally passes solar system tests. Observation protocols will be discussed in this wider framework.

Stimulus and recording variables and their effects on mammalian vestibular evoked potentials

NASA Technical Reports Server (NTRS)

Jones, Sherri M.; Subramanian, Geetha; Avniel, Wilma; Guo, Yuqing; Burkard, Robert F.; Jones, Timothy A.

2002-01-01

Linear vestibular evoked potentials (VsEPs) measure the collective neural activity of the gravity receptor organs in the inner ear that respond to linear acceleration transients. The present study examined the effects of electrode placement, analog filtering, stimulus polarity and stimulus rate on linear VsEP thresholds, latencies and amplitudes recorded from mice. Two electrode-recording montages were evaluated, rostral (forebrain) to 'mastoid' and caudal (cerebellum) to 'mastoid'. VsEP thresholds and peak latencies were identical between the two recording sites; however, peak amplitudes were larger for the caudal recording montage. VsEPs were also affected by filtering. Results suggest optimum high pass filter cutoff at 100-300 Hz, and low pass filter cutoff at 10,000 Hz. To evaluate stimulus rate, linear jerk pulses were presented at 9.2, 16, 25, 40 and 80 Hz. At 80 Hz, mean latencies were longer (0.350-0.450 ms) and mean amplitudes reduced (0.8-1.8 microV) for all response peaks. In 50% of animals, late peaks (P3, N3) disappeared at 80 Hz. The results offer options for VsEP recording protocols. Copyright 2002 Elsevier Science B.V.

Region-specific reduction of auditory sensory gating in older adults.

PubMed

Cheng, Chia-Hsiung; Baillet, Sylvain; Lin, Yung-Yang

2015-12-01

Aging has been associated with declines in sensory-perceptual processes. Sensory gating (SG), or repetition suppression, refers to the attenuation of neural activity in response to a second stimulus and is considered to be an automatic process to inhibit redundant sensory inputs. It is controversial whether SG deficits, as tested with an auditory paired-stimulus protocol, accompany normal aging in humans. To reconcile the debates arising from event-related potential studies, we recorded auditory neuromagnetic reactivity in 20 young and 19 elderly adult men and determined the neural activation by using minimum-norm estimate (MNE) source modeling. SG of M100 was calculated by the ratio of the response to the second stimulus over that to the first stimulus. MNE results revealed that fronto-temporo-parietal networks were implicated in the M100 SG. Compared to the younger participants, the elderly showed selectively increased SG ratios in the anterior superior temporal gyrus, anterior middle temporal gyrus, temporal pole and orbitofrontal cortex, suggesting an insufficient age-related gating to repetitive auditory stimulation. These findings also highlight the loss of frontal inhibition of the auditory cortex in normal aging. Copyright © 2015 Elsevier Inc. All rights reserved.

Pyff - a pythonic framework for feedback applications and stimulus presentation in neuroscience.

PubMed

Venthur, Bastian; Scholler, Simon; Williamson, John; Dähne, Sven; Treder, Matthias S; Kramarek, Maria T; Müller, Klaus-Robert; Blankertz, Benjamin

2010-01-01

This paper introduces Pyff, the Pythonic feedback framework for feedback applications and stimulus presentation. Pyff provides a platform-independent framework that allows users to develop and run neuroscientific experiments in the programming language Python. Existing solutions have mostly been implemented in C++, which makes for a rather tedious programming task for non-computer-scientists, or in Matlab, which is not well suited for more advanced visual or auditory applications. Pyff was designed to make experimental paradigms (i.e., feedback and stimulus applications) easily programmable. It includes base classes for various types of common feedbacks and stimuli as well as useful libraries for external hardware such as eyetrackers. Pyff is also equipped with a steadily growing set of ready-to-use feedbacks and stimuli. It can be used as a standalone application, for instance providing stimulus presentation in psychophysics experiments, or within a closed loop such as in biofeedback or brain-computer interfacing experiments. Pyff communicates with other systems via a standardized communication protocol and is therefore suitable to be used with any system that may be adapted to send its data in the specified format. Having such a general, open-source framework will help foster a fruitful exchange of experimental paradigms between research groups. In particular, it will decrease the need of reprogramming standard paradigms, ease the reproducibility of published results, and naturally entail some standardization of stimulus presentation.

Pyff – A Pythonic Framework for Feedback Applications and Stimulus Presentation in Neuroscience

PubMed Central

Venthur, Bastian; Scholler, Simon; Williamson, John; Dähne, Sven; Treder, Matthias S.; Kramarek, Maria T.; Müller, Klaus-Robert; Blankertz, Benjamin

2010-01-01

This paper introduces Pyff, the Pythonic feedback framework for feedback applications and stimulus presentation. Pyff provides a platform-independent framework that allows users to develop and run neuroscientific experiments in the programming language Python. Existing solutions have mostly been implemented in C++, which makes for a rather tedious programming task for non-computer-scientists, or in Matlab, which is not well suited for more advanced visual or auditory applications. Pyff was designed to make experimental paradigms (i.e., feedback and stimulus applications) easily programmable. It includes base classes for various types of common feedbacks and stimuli as well as useful libraries for external hardware such as eyetrackers. Pyff is also equipped with a steadily growing set of ready-to-use feedbacks and stimuli. It can be used as a standalone application, for instance providing stimulus presentation in psychophysics experiments, or within a closed loop such as in biofeedback or brain–computer interfacing experiments. Pyff communicates with other systems via a standardized communication protocol and is therefore suitable to be used with any system that may be adapted to send its data in the specified format. Having such a general, open-source framework will help foster a fruitful exchange of experimental paradigms between research groups. In particular, it will decrease the need of reprogramming standard paradigms, ease the reproducibility of published results, and naturally entail some standardization of stimulus presentation. PMID:21160550

British Columbia/Alberta Transfer System Protocol

ERIC Educational Resources Information Center

British Columbia Council on Admissions and Transfer, 2007

2007-01-01

The purpose of this agreement is to provide assurance to students that they will receive transfer credit for courses or programs they have successfully completed where the content/outcomes are demonstrably equivalent to those offered at the institution to which they transfer. This protocol is undertaken by the British Columbia Council on…

Assessment of Murine Retinal Function by Electroretinography

PubMed Central

Benchorin, Gillie; Calton, Melissa A.; Beaulieu, Marielle O.; Vollrath, Douglas

2017-01-01

The electroretinogram (ERG) is a sensitive and noninvasive method for testing retinal function. In this protocol, we describe a method for performing ERGs in mice. Contact lenses on the mouse cornea measure the electrical response to a light stimulus of photoreceptors and downstream retinal cells, and the collected data are analyzed to evaluate retinal function. PMID:29177186

The Versatility of SpAM: A Fast, Efficient, Spatial Method of Data Collection for Multidimensional Scaling

ERIC Educational Resources Information Center

Hout, Michael C.; Goldinger, Stephen D.; Ferguson, Ryan W.

2013-01-01

Although traditional methods to collect similarity data (for multidimensional scaling [MDS]) are robust, they share a key shortcoming. Specifically, the possible pairwise comparisons in any set of objects grow rapidly as a function of set size. This leads to lengthy experimental protocols, or procedures that involve scaling stimulus subsets. We…

Suboptimal choice in rats: incentive salience attribution promotes maladaptive decision-making

PubMed Central

Chow, Jonathan J; Smith, Aaron P; Wilson, A George; Zentall, Thomas R; Beckmann, Joshua S

2016-01-01

Stimuli that are more predictive of subsequent reward also function as better conditioned reinforcers. Moreover, stimuli attributed with incentive salience function as more robust conditioned reinforcers. Some theories have suggested that conditioned reinforcement plays an important role in promoting suboptimal choice behavior, like gambling. The present experiments examined how different stimuli, those attributed with incentive salience versus those without, can function in tandem with stimulus-reward predictive utility to promote maladaptive decision-making in rats. One group of rats had lights associated with goal-tracking as the reward-predictive stimuli and another had levers associated with sign-tracking as the reward-predictive stimuli. All rats were first trained on a choice procedure in which the expected value across both alternatives was equivalent but differed in their stimulus-reward predictive utility. Next, the expected value across both alternatives was systematically changed so that the alternative with greater stimulus-reward predictive utility was suboptimal in regard to primary reinforcement. The results demonstrate that in order to obtain suboptimal choice behavior, incentive salience alongside strong stimulus-reward predictive utility may be necessary; thus, maladaptive decision-making can be driven more by the value attributed to stimuli imbued with incentive salience that reliably predict a reward rather than the reward itself. PMID:27993692

Suboptimal choice in rats: Incentive salience attribution promotes maladaptive decision-making.

PubMed

Chow, Jonathan J; Smith, Aaron P; Wilson, A George; Zentall, Thomas R; Beckmann, Joshua S

2017-03-01

Stimuli that are more predictive of subsequent reward also function as better conditioned reinforcers. Moreover, stimuli attributed with incentive salience function as more robust conditioned reinforcers. Some theories have suggested that conditioned reinforcement plays an important role in promoting suboptimal choice behavior, like gambling. The present experiments examined how different stimuli, those attributed with incentive salience versus those without, can function in tandem with stimulus-reward predictive utility to promote maladaptive decision-making in rats. One group of rats had lights associated with goal-tracking as the reward-predictive stimuli and another had levers associated with sign-tracking as the reward-predictive stimuli. All rats were first trained on a choice procedure in which the expected value across both alternatives was equivalent but differed in their stimulus-reward predictive utility. Next, the expected value across both alternatives was systematically changed so that the alternative with greater stimulus-reward predictive utility was suboptimal in regard to primary reinforcement. The results demonstrate that in order to obtain suboptimal choice behavior, incentive salience alongside strong stimulus-reward predictive utility may be necessary; thus, maladaptive decision-making can be driven more by the value attributed to stimuli imbued with incentive salience that reliably predict a reward rather than the reward itself. Copyright © 2016 Elsevier B.V. All rights reserved.

Near-field visual acuity of pigeons: effects of head location and stimulus luminance.

PubMed

Hodos, W; Leibowitz, R W; Bonbright, J C

1976-03-01

Two pigeons were trained to discriminate a grating stimulus from a blank stimulus of equivalent luminance in a three-key chamber. The stimuli and blanks were presented behind a transparent center key. The procedure was a conditional discrimination in which pecks on the left key were reinforced if the blank had been present behind the center key and pecks on the right key were reinforced if the grating had been present behind the center key. The spatial frequency of the stimuli was varied in each session from four to 29.5 lines per millimeter in accordance with a variation of the method of constant stimuli. The number of lines per millimeter that the subjects could discriminate at threshold was determined from psychometric functions. Data were collected at five values of stimulus luminance ranging from--0.07 to 3.29 log cd/m2. The distance from the stimulus to the anterior nodal point of the eye, which was determined from measurements taken from high-speed motion-picture photographs of three additional pigeons and published intraocular measurements, was 62.0 mm. This distance and the grating detection thresholds were used to calculate the visual acuity of the birds at each level of luminance. Acuity improved with increasing luminance to a peak value of 0.52, which corresponds to a visual angle of 1.92 min, at a luminance of 2.33 log cd/m2. Further increase in luminance produced a small decline in acuity.

A Derived Relations Analysis of Approach-Avoidance Conflict: Implications for the Behavioral Analysis of Human Anxiety

ERIC Educational Resources Information Center

Gannon, Steven; Roche, Bryan; Kanter, Jonathan W.; Forsyth, John P.; Linehan, Conor

2011-01-01

The current article reports two experiments designed to examine the effects of creating competing approach and avoidance response functions for 2 stimuli that participate in the same derived stimulus relation. Experiment 1 involved establishing each of 2 distinct members (i.e., B1 and D1) of the same 1-node equivalence relation (A-B-C-D) as a…

The acute effects of manipulating volume and load of back squats on countermovement vertical jump performance.

PubMed

Moir, Gavin L; Mergy, David; Witmer, Ca; Davis, Shala E

2011-06-01

The acute effects of manipulating the volume and load of back squats on subsequent countermovement vertical jump performance were investigated in the present study. Eleven National Collegiate Athletic Association division II female volleyball players performed 10 countermovement vertical jumps (CMJs) on a force platform 2 minutes after the last squat repetition of a high-load (HL) or high-volume (HV) squat protocol. Two minutes of rest was provided between each CMJ. The HL protocol culminated in the subjects having to perform 3 repetitions with a load equivalent to 90% 1 repetition maximum (1RM) back squat, whereas 12 repetitions with a load equivalent to 37% 1RM were performed in the HV protocol. During an initial familiarization session, knee angles were recorded during a series of CMJs, and these angles were used to control the depth of descent during all subsequent back squats. Jump height (JH) and vertical stiffness (VStiff) were calculated during each of the 10 CMJ, and the change in these variables after the 2 squat protocols was assessed using an analysis of variance model with repeated measures on 2 factors (Protocol [2-levels]; Time [2-levels]). There was no significant difference in JH after the HL and HV protocols (p > 0.05). A significant Protocol × Time interaction for VStiff resulted from the increase after the HL protocol being greater than that after the HV protocol (p = 0.03). The knee angles before the HL and HV protocols were significantly greater than those measured during the initial familiarization session (p = 0.001). Although neither squat protocol provided any benefit in improving JH, the heavy squat protocol produced greater increases in VStiff during the CMJ. Because of the increased VStiff caused by the HL protocol, volleyball coaches may consider using such protocols with their players to improve performance in jumps performed from a run such as the spike and on-court agility.

Big Stimulus, Little Ears: Safety in Administering Vestibular Evoked Myogenic Potentials (VEMP) in Children

PubMed Central

Thomas, Megan L.A.; Fitzpatrick, Denis; McCreery, Ryan; Janky, Kristen L.

2017-01-01

Background Cervical and ocular Vestibular Evoked Myogenic Potentials (VEMPs) have become common clinical vestibular assessments. However, VEMP testing requires high intensity stimuli, raising concerns regarding safety with children, where sound pressure levels may be higher due to their smaller ear canal volumes. Purpose The purpose of this study was to estimate the range of peak-to-peak equivalent sound pressure levels (peSPLs) in child and adult ears in response to high intensity stimuli (i.e., 100 dB normal hearing level (nHL)) commonly used for VEMP testing and make a determination of whether acoustic stimuli levels with VEMP testing are safe for use in children. Research Design Prospective Experimental. Study Sample Ten children (4–6 years) and ten young adults (24 – 35 years) with normal hearing sensitivity and middle ear function participated in the study. Data Collection and Analysis Probe microphone peSPL measurements of clicks and 500 Hz tonebursts (TBs) were recorded in tubes of small, medium, and large diameter, and in a Brüel & Kjær Ear Simulator Type 4157 to assess for linearity of the stimulus at high levels. The different diameter tubes were used to approximate the range of cross-sectional areas in infant, child, and adult ears, respectively. Equivalent ear canal volume and peSPL measurements were then recorded in child and adult ears. Lower intensity levels were used in the participant’s ears to limit exposure to high intensity sound. The peSPL measurements in participant ears were extrapolated using predictions from linear mixed models to determine if equivalent ear canal volume significantly contributed to overall peSPL and to estimate the mean and 95% confidence intervals of peSPLs in child and adult ears when high intensity stimulus levels (100 dB nHL) are used for VEMP testing without exposing subjects to high-intensity stimuli. Results Measurements from the coupler and tubes suggested: 1) each stimuli was linear, 2) there were no distortions or non-linearities at high levels, and 3) peSPL increased with decreased tube diameter. Measurements in participant ears suggested: 1) peSPL was approximately 3 dB larger in child compared to adult ears, and 2) peSPL was larger in response to clicks compared to 500 Hz TBs. The model predicted the following 95% confidence interval for a 100 dB nHL click: 127–136.5 dB peSPL in adult ears and 128.7–138.2 dB peSPL in child ears. The model predicted the following 95% confidence interval for a 100 dB nHL 500 Hz TB stimulus: 122.2 – 128.2 dB peSPL in adult ears and 124.8–130.8 dB peSPL in child ears. Conclusions Our findings suggest that 1) when completing VEMP testing, the stimulus is approximately 3 dB higher in a child’s ear, 2) a 500 Hz TB is recommended over a click as it has lower peSPL compared to the click, and 3) both duration and intensity should be considered when choosing VEMP stimuli. Calculating the total sound energy exposure for your chosen stimuli is recommended as it accounts for both duration and intensity. When using this calculation for children, consider adding 3 dB to the stimulus level. PMID:28534730

Big Stimulus, Little Ears: Safety in Administering Vestibular-Evoked Myogenic Potentials in Children.

PubMed

Thomas, Megan L A; Fitzpatrick, Denis; McCreery, Ryan; Janky, Kristen L

2017-05-01

Cervical and ocular vestibular-evoked myogenic potentials (VEMPs) have become common clinical vestibular assessments. However, VEMP testing requires high intensity stimuli, raising concerns regarding safety with children, where sound pressure levels may be higher due to their smaller ear canal volumes. The purpose of this study was to estimate the range of peak-to-peak equivalent sound pressure levels (peSPLs) in child and adult ears in response to high intensity stimuli (i.e., 100 dB normal hearing level [nHL]) commonly used for VEMP testing and make a determination of whether acoustic stimuli levels with VEMP testing are safe for use in children. Prospective experimental. Ten children (4-6 years) and ten young adults (24-35 years) with normal hearing sensitivity and middle ear function participated in the study. Probe microphone peSPL measurements of clicks and 500 Hz tonebursts (TBs) were recorded in tubes of small, medium, and large diameter, and in a Brüel & Kjær Ear Simulator Type 4157 to assess for linearity of the stimulus at high levels. The different diameter tubes were used to approximate the range of cross-sectional areas in infant, child, and adult ears, respectively. Equivalent ear canal volume and peSPL measurements were then recorded in child and adult ears. Lower intensity levels were used in the participant's ears to limit exposure to high intensity sound. The peSPL measurements in participant ears were extrapolated using predictions from linear mixed models to determine if equivalent ear canal volume significantly contributed to overall peSPL and to estimate the mean and 95% confidence intervals of peSPLs in child and adult ears when high intensity stimulus levels (100 dB nHL) are used for VEMP testing without exposing subjects to high-intensity stimuli. Measurements from the coupler and tubes suggested: 1) each stimuli was linear, 2) there were no distortions or nonlinearities at high levels, and 3) peSPL increased with decreased tube diameter. Measurements in participant ears suggested: 1) peSPL was approximately 3 dB larger in child compared to adult ears, and 2) peSPL was larger in response to clicks compared to 500 Hz TBs. The model predicted the following 95% confidence interval for a 100 dB nHL click: 127-136.5 dB peSPL in adult ears and 128.7-138.2 dB peSPL in child ears. The model predicted the following 95% confidence interval for a 100 dB nHL 500 Hz TB stimulus: 122.2-128.2 dB peSPL in adult ears and 124.8-130.8 dB peSPL in child ears. Our findings suggest that 1) when completing VEMP testing, the stimulus is approximately 3 dB higher in a child's ear, 2) a 500 Hz TB is recommended over a click as it has lower peSPL compared to the click, and 3) both duration and intensity should be considered when choosing VEMP stimuli. Calculating the total sound energy exposure for your chosen stimuli is recommended as it accounts for both duration and intensity. When using this calculation for children, consider adding 3 dB to the stimulus level. American Academy of Audiology

Decision-Making under Ambiguity Is Modulated by Visual Framing, but Not by Motor vs. Non-Motor Context. Experiments and an Information-Theoretic Ambiguity Model

PubMed Central

Grau-Moya, Jordi; Ortega, Pedro A.; Braun, Daniel A.

2016-01-01

A number of recent studies have investigated differences in human choice behavior depending on task framing, especially comparing economic decision-making to choice behavior in equivalent sensorimotor tasks. Here we test whether decision-making under ambiguity exhibits effects of task framing in motor vs. non-motor context. In a first experiment, we designed an experience-based urn task with varying degrees of ambiguity and an equivalent motor task where subjects chose between hitting partially occluded targets. In a second experiment, we controlled for the different stimulus design in the two tasks by introducing an urn task with bar stimuli matching those in the motor task. We found ambiguity attitudes to be mainly influenced by stimulus design. In particular, we found that the same subjects tended to be ambiguity-preferring when choosing between ambiguous bar stimuli, but ambiguity-avoiding when choosing between ambiguous urn sample stimuli. In contrast, subjects’ choice pattern was not affected by changing from a target hitting task to a non-motor context when keeping the stimulus design unchanged. In both tasks subjects’ choice behavior was continuously modulated by the degree of ambiguity. We show that this modulation of behavior can be explained by an information-theoretic model of ambiguity that generalizes Bayes-optimal decision-making by combining Bayesian inference with robust decision-making under model uncertainty. Our results demonstrate the benefits of information-theoretic models of decision-making under varying degrees of ambiguity for a given context, but also demonstrate the sensitivity of ambiguity attitudes across contexts that theoretical models struggle to explain. PMID:27124723

Decision-Making under Ambiguity Is Modulated by Visual Framing, but Not by Motor vs. Non-Motor Context. Experiments and an Information-Theoretic Ambiguity Model.

PubMed

Grau-Moya, Jordi; Ortega, Pedro A; Braun, Daniel A

2016-01-01

A number of recent studies have investigated differences in human choice behavior depending on task framing, especially comparing economic decision-making to choice behavior in equivalent sensorimotor tasks. Here we test whether decision-making under ambiguity exhibits effects of task framing in motor vs. non-motor context. In a first experiment, we designed an experience-based urn task with varying degrees of ambiguity and an equivalent motor task where subjects chose between hitting partially occluded targets. In a second experiment, we controlled for the different stimulus design in the two tasks by introducing an urn task with bar stimuli matching those in the motor task. We found ambiguity attitudes to be mainly influenced by stimulus design. In particular, we found that the same subjects tended to be ambiguity-preferring when choosing between ambiguous bar stimuli, but ambiguity-avoiding when choosing between ambiguous urn sample stimuli. In contrast, subjects' choice pattern was not affected by changing from a target hitting task to a non-motor context when keeping the stimulus design unchanged. In both tasks subjects' choice behavior was continuously modulated by the degree of ambiguity. We show that this modulation of behavior can be explained by an information-theoretic model of ambiguity that generalizes Bayes-optimal decision-making by combining Bayesian inference with robust decision-making under model uncertainty. Our results demonstrate the benefits of information-theoretic models of decision-making under varying degrees of ambiguity for a given context, but also demonstrate the sensitivity of ambiguity attitudes across contexts that theoretical models struggle to explain.

On Equivalence between Critical Probabilities of Dynamic Gossip Protocol and Static Site Percolation

NASA Astrophysics Data System (ADS)

Ishikawa, Tetsuya; Hayakawa, Tomohisa

The relationship between the critical probability of gossip protocol on the square lattice and the critical probability of site percolation on the square lattice is discussed. Specifically, these two critical probabilities are analytically shown to be equal to each other. Furthermore, we present a way of evaluating the critical probability of site percolation by approximating the saturation of gossip protocol. Finally, we provide numerical results which support the theoretical analysis.

More Similar but Less Satisfying: Comparing Preferences for and the Efficacy of Within- and Cross-Category Substitutes for Food.

PubMed

Huh, Young Eun; Vosgerau, Joachim; Morewedge, Carey K

2016-06-01

When people cannot get what they want, they often satisfy their desire by consuming a substitute. Substitutes can originate from within the taxonomic category of the desired stimulus (i.e., within-category substitutes) or from a different taxonomic category that serves the same basic goal (i.e., cross-category substitutes). Both a store-brand chocolate (within-category substitute) and a granola bar (cross-category substitute), for example, can serve as substitutes for gourmet chocolate. Here, we found that people believe that within-category substitutes, which are more similar to desired stimuli, will more effectively satisfy their cravings than will cross-category substitutes (Experiments 1, 2a, and 2b). However, because within-category substitutes are more similar than cross-category substitutes to desired stimuli, they are more likely to evoke an unanticipated negative contrast effect. As a result, unless substitutes are equivalent in quality to the desired stimulus, cross-category substitutes more effectively satisfy cravings for the desired stimulus (Experiments 3 and 4). © The Author(s) 2016.

A successful search for symmetry (and other derived relations) in the conditional discriminations of pigeons 1, 2

PubMed Central

Urcuioli, Peter J.

2017-01-01

Symmetry is one of three derived relations (along with transitivity and reflexivity) that indicate that explicitly trained conditional relations are equivalence relations and that the elements of those trained relations are members of a stimulus class. Although BA symmetry is typically observed after AB conditional discrimination training in humans, it has been an elusive phenomenon in other animals until just recently. This paper describes past unsuccessful attempts to observe symmetry in non-human animals and the likely reasons for that lack of success. I then describe how methodological changes made in response to the earlier findings have now yielded robust evidence for symmetry in pigeons, and what these changes indicate about the functional matching stimuli. Finally, I describe a theory of stimulus-class formation (Urcuioli, 2008) which specifies how and why symmetry and other derived relations arise from different sets of trained relations. These derived relations are noteworthy because they demonstrate an impressive repertoire of non-similarity-based categorization effects in animals and the generative effects of reinforcement and stimulus control processes on behavior. PMID:28386579

Enhancement of antibody response by one-trial conditioning: contrasting results using different antigens.

PubMed

Espinosa, Enrique; Calderas, Tania; Flores-Muciño, Oscar; Pérez-García, Georgina; Vázquez-Camacho, Ana C; Bermúdez-Rattoni, Federico

2004-01-01

New research in conditioned enhancement of antibody response requires a general paradigm effective with different antigens. In this experiment series we applied a one-trial protocol using keyhole limpet hemocyanin immunization as an unconditioned stimulus. Several different conditions were tested. Two different times between conditioning and test trial, two relevant antigen doses and the use of an antigen booster during test trial were investigated. We did not find a conditioned effect in any of the conditions used. In contrast, we found a reliable albeit modest conditioned effect using hen egg lysozyme as unconditioned stimulus. By comparing these and other findings we conclude that the number of conditioning trials is a possible requirement for a more reliable conditioning of antibody response.

Does temporal contiguity moderate contingency learning in a speeded performance task?

PubMed

Schmidt, James R; De Houwer, Jan

2012-01-01

In four experiments, we varied the time between the onset of distracting nonwords and target colour words in a word-word version of the colour-word contingency learning paradigm. Contingencies were created by pairing a distractor nonword more often with one target colour word than with other colour words. A contingency effect corresponds to faster responses to the target colour word on high-contingency trials (i.e., distractor nonword followed by the target colour word with which it appears most often) than on low-contingency trials (i.e., distractor nonword followed by a target colour word with which it appears only occasionally). Roughly equivalent-sized contingency effects were found at stimulus-onset asynchronies (SOAs) of 50, 250, and 450 ms in Experiment 1, and 50, 500, and 1,000 ms in Experiment 2. In Experiment 3, a contingency effect was observed at SOAs of -50, -200, and -350 ms. In Experiment 4, interstimulus interval (ISI) was varied along with SOA, and learning was equivalent for 200-, 700-, and 1,200-ms SOAs. Together, these experiments suggest that the distracting stimulus does not need to be presented in close temporal contiguity with the response to induce learning. Relations to past research on causal judgement and implications for further contingency learning research are discussed.

Impairment of willed actions and use of advance information for movement preparation in schizophrenia

PubMed Central

Fuller, R.; Jahanshahi, M.

1999-01-01

OBJECTIVES—To assess willed actions in patients with schizophrenia using reaction time (RT) tasks that differ in the degree to which they involve volitionally controlled versus stimulus driven responses.
METHODS—Ten patients diagnosed with schizophrenia and 13 normal controls of comparable age were tested. Subjects performed a visual simple RT (SRT), an uncued four choice reaction time (CRT), and a fully cued four choice RT task. A stimulus 1(S1)−stimulus 2(S2) paradigm was used. The warning signal/precue (S1) preceded the imperative stimulus (S2) by either 0 (no warning signal or precue) 200, 800, 1600, or 3200ms.
RESULTS—The patients with schizophrenia had significantly slower RTs and movement times than normal subjects across all RT tasks. The unwarned SRT trials were significantly faster than the uncued CRT trials for both groups. For both groups, fully cued CRTs were significantly faster than the uncued CRTs. However, the S1−S2 interval had a differential effect on CRTs in the two groups. For the normal subjects fully cued CRTs and SRTs were equivalent when S1-S2 intervals were 800 ms or longer. A similar pattern of effects was not seen in the patients with schizophrenia, for whom the fully cued CRT were unexpectedly equivalent to SRT for the 200 ms interval and expectedly for the 1600 ms S1-S2 interval, but not the 3200 or 800 ms intervals.
CONCLUSIONS—Patients with schizophrenia were able to use advance information inherent in SRT or provided by the precue in fully cued CRT to speed up RT relative to uncued CRT. However, in the latter task, in which the volitional demands of preprogramming are higher since a different response has to be prepared on each trial, patients showed some unusual and inconsistent interval effects suggesting instability of attentional set. It is possible that future studies using RT tasks with higher volitional demands in patients with predominance of negative signs may disclose greater deficits in willed action in schizophrenia.

 PMID:10201424

Talk-Aloud Protocols during Conditional Discrimination Training and Equivalence Class Formation

ERIC Educational Resources Information Center

Vie, Aleksander; Arntzen, Erik

2017-01-01

The primary focus of the present experiment was to study participants' self-talk during conditional discrimination training and test for the emergence of conditional relations consistent with equivalence. Eighteen adult participants were exposed to either a Many-to-One (MTO) or a One-to-Many (OTM) training structure arranged as a 6-s delayed…

Conditioned [corrected] stimulus informativeness governs conditioned stimulus-unconditioned stimulus associability.

PubMed

Ward, Ryan D; Gallistel, C R; Jensen, Greg; Richards, Vanessa L; Fairhurst, Stephen; Balsam, Peter D

2012-07-01

In a conditioning protocol, the onset of the conditioned stimulus ([CS]) provides information about when to expect reinforcement (unconditioned stimulus [US]). There are two sources of information from the CS in a delay conditioning paradigm in which the CS-US interval is fixed. The first depends on the informativeness, the degree to which CS onset reduces the average expected time to onset of the next US. The second depends only on how precisely a subject can represent a fixed-duration interval (the temporal Weber fraction). In three experiments with mice, we tested the differential impact of these two sources of information on rate of acquisition of conditioned responding (CS-US associability). In Experiment 1, we showed that associability (the inverse of trials to acquisition) increased in proportion to informativeness. In Experiment 2, we showed that fixing the duration of the US-US interval or the CS-US interval or both had no effect on associability. In Experiment 3, we equated the increase in information produced by varying the C/T ratio with the increase produced by fixing the duration of the CS-US interval. Associability increased with increased informativeness, but, as in Experiment 2, fixing the CS-US duration had no effect on associability. These results are consistent with the view that CS-US associability depends on the increased rate of reward signaled by CS onset. The results also provide further evidence that conditioned responding is temporally controlled when it emerges.

Single neuron firing properties impact correlation-based population coding

PubMed Central

Hong, Sungho; Ratté, Stéphanie; Prescott, Steven A.; De Schutter, Erik

2012-01-01

Correlated spiking has been widely observed but its impact on neural coding remains controversial. Correlation arising from co-modulation of rates across neurons has been shown to vary with the firing rates of individual neurons. This translates into rate and correlation being equivalently tuned to the stimulus; under those conditions, correlated spiking does not provide information beyond that already available from individual neuron firing rates. Such correlations are irrelevant and can reduce coding efficiency by introducing redundancy. Using simulations and experiments in rat hippocampal neurons, we show here that pairs of neurons receiving correlated input also exhibit correlations arising from precise spike-time synchronization. Contrary to rate co-modulation, spike-time synchronization is unaffected by firing rate, thus enabling synchrony- and rate-based coding to operate independently. The type of output correlation depends on whether intrinsic neuron properties promote integration or coincidence detection: “ideal” integrators (with spike generation sensitive to stimulus mean) exhibit rate co-modulation whereas “ideal” coincidence detectors (with spike generation sensitive to stimulus variance) exhibit precise spike-time synchronization. Pyramidal neurons are sensitive to both stimulus mean and variance, and thus exhibit both types of output correlation proportioned according to which operating mode is dominant. Our results explain how different types of correlations arise based on how individual neurons generate spikes, and why spike-time synchronization and rate co-modulation can encode different stimulus properties. Our results also highlight the importance of neuronal properties for population-level coding insofar as neural networks can employ different coding schemes depending on the dominant operating mode of their constituent neurons. PMID:22279226

Learning to inhibit the response during instrumental (operant) extinction

PubMed Central

Bouton, Mark E.; Trask, Sydney; Carranza-Jasso, Rodrigo

2016-01-01

Five experiments tested implications of the idea that instrumental (operant) extinction involves learning to inhibit the learned response. All experiments used a discriminated operant procedure in which rats were reinforced for lever pressing or chain pulling in the presence of a discriminative stimulus (S), but not in its absence. In Experiment 1, extinction of the response (R) in the presence of S weakened responding in S, but equivalent nonreinforced exposure to S (without the opportunity to make R) did not. Experiment 2 replicated that result and found that extinction of R had no effect on a different R that had also been reinforced in the stimulus. In Experiments 3 and 4, rats first learned to perform several different stimulus and response combinations (S1R1, S2R1, S3R2, and S4R2). Extinction of a response in one stimulus (i.e., S1R1) transferred and weakened the same response, but not a different response, when it was tested in another stimulus (i.e., S2R1 but not S3R2). In Experiment 5, extinction still transferred between S1 and S2 when the stimuli set the occasion for R's association with different types of food pellets. The results confirm the importance of response inhibition in instrumental extinction: Nonreinforcement of the response in S causes the most effective suppression of responding, and response suppression is specific to the response but transfers and influences performance of the same response when it is occasioned by other stimuli. Theoretical and practical implications are discussed. PMID:27379715

Missing data handling in non-inferiority and equivalence trials: A systematic review.

PubMed

Rabe, Brooke A; Day, Simon; Fiero, Mallorie H; Bell, Melanie L

2018-05-25

Non-inferiority (NI) and equivalence clinical trials test whether a new treatment is therapeutically no worse than, or equivalent to, an existing standard of care. Missing data in clinical trials have been shown to reduce statistical power and potentially bias estimates of effect size; however, in NI and equivalence trials, they present additional issues. For instance, they may decrease sensitivity to differences between treatment groups and bias toward the alternative hypothesis of NI (or equivalence). Our primary aim was to review the extent of and methods for handling missing data (model-based methods, single imputation, multiple imputation, complete case), the analysis sets used (Intention-To-Treat, Per-Protocol, or both), and whether sensitivity analyses were used to explore departures from assumptions about the missing data. We conducted a systematic review of NI and equivalence trials published between May 2015 and April 2016 by searching the PubMed database. Articles were reviewed primarily by 2 reviewers, with 6 articles reviewed by both reviewers to establish consensus. Of 109 selected articles, 93% reported some missing data in the primary outcome. Among those, 50% reported complete case analysis, and 28% reported single imputation approaches for handling missing data. Only 32% reported conducting analyses of both intention-to-treat and per-protocol populations. Only 11% conducted any sensitivity analyses to test assumptions with respect to missing data. Missing data are common in NI and equivalence trials, and they are often handled by methods which may bias estimates and lead to incorrect conclusions. Copyright © 2018 John Wiley & Sons, Ltd.

Effects of High Sound Exposure During Air-Conducted Vestibular Evoked Myogenic Potential Testing in Children and Young Adults.

PubMed

Rodriguez, Amanda I; Thomas, Megan L A; Fitzpatrick, Denis; Janky, Kristen L

Vestibular evoked myogenic potential (VEMP) testing is increasingly utilized in pediatric vestibular evaluations due to its diagnostic capability to identify otolith dysfunction and feasibility of testing. However, there is evidence demonstrating that the high-intensity stimulation level required to elicit a reliable VEMP response causes acoustic trauma in adults. Despite utility of VEMP testing in children, similar findings are unknown. It is hypothesized that increased sound exposure may exist in children because differences in ear-canal volume (ECV) compared with adults, and the effect of stimulus parameters (e.g., signal duration and intensity) will alter exposure levels delivered to a child's ear. The objectives of this study are to (1) measure peak to peak equivalent sound pressure levels (peSPL) in children with normal hearing (CNH) and young adults with normal hearing (ANH) using high-intensity VEMP stimuli, (2) determine the effect of ECV on peSPL and calculate a safe exposure level for VEMP, and (3) assess whether cochlear changes exist after VEMP exposure. This was a 2-phase approach. Fifteen CNH and 12 ANH participated in phase I. Equivalent ECV was measured. In 1 ear, peSPL was recorded for 5 seconds at 105 to 125 dB SPL, in 5-dB increments for 500- and 750-Hz tone bursts. Recorded peSPL values (accounting for stimulus duration) were then used to calculate safe sound energy exposure values for VEMP testing using the 132-dB recommended energy allowance from the 2003 European Union Guidelines. Fifteen CNH and 10 ANH received cervical and ocular VEMP testing in 1 ear in phase II. Subjects completed tympanometry, pre- and postaudiometric threshold testing, distortion product otoacoustic emissions, and questionnaire addressing subjective otologic symptoms to study the effect of VEMP exposure on cochlear function. (1) In response to high-intensity stimulation levels (e.g., 125 dB SPL), CNH had significantly higher peSPL measurements and smaller ECVs compared with ANH. (2) A significant linear relationship between equivalent ECV (as measured by diagnostic tympanometry) and peSPL exists and has an effect on total sound energy exposure level; based on data from phase I, 120 dB SPL was determined to be an acoustically safe stimulation level for testing in children. (3) Using calculated safe stimulation level for VEMP testing, there were no significant effect of VEMP exposure on cochlear function (as measured by audiometric thresholds, distortion product otoacoustic emission amplitude levels, or subjective symptoms) in CNH and ANH. peSPL sound recordings in children's ears are significantly higher (~3 dB) than that in adults in response to high-intensity VEMP stimuli that are commonly practiced. Equivalent ECV contributes to peSPL delivered to the ear during VEMP testing and should be considered to determine safe acoustic VEMP stimulus parameters; children with smaller ECVs are at risk for unsafe sound exposure during routine VEMP testing, and stimuli should not exceed 120 dB SPL. Using 120 dB SPL stimulus level for children during VEMP testing yields no change to cochlear function and reliable VEMP responses.

Impaired Contingent Attentional Capture Predicts Reduced Working Memory Capacity in Schizophrenia

PubMed Central

Mayer, Jutta S.; Fukuda, Keisuke; Vogel, Edward K.; Park, Sohee

2012-01-01

Although impairments in working memory (WM) are well documented in schizophrenia, the specific factors that cause these deficits are poorly understood. In this study, we hypothesized that a heightened susceptibility to attentional capture at an early stage of visual processing would result in working memory encoding problems. 30 patients with schizophrenia and 28 demographically matched healthy participants were presented with a search array and asked to report the orientation of the target stimulus. In some of the trials, a flanker stimulus preceded the search array that either matched the color of the target (relevant-flanker capture) or appeared in a different color (irrelevant-flanker capture). Working memory capacity was determined in each individual using the visual change detection paradigm. Patients needed considerably more time to find the target in the no-flanker condition. After adjusting the individual exposure time, both groups showed equivalent capture costs in the irrelevant-flanker condition. However, in the relevant-flanker condition, capture costs were increased in patients compared to controls when the stimulus onset asynchrony between the flanker and the search array was high. Moreover, the increase in relevant capture costs correlated negatively with working memory capacity. This study demonstrates preserved stimulus-driven attentional capture but impaired contingent attentional capture associated with low working memory capacity in schizophrenia. These findings suggest a selective impairment of top-down attentional control in schizophrenia, which may impair working memory encoding. PMID:23152783

Impaired contingent attentional capture predicts reduced working memory capacity in schizophrenia.

PubMed

Mayer, Jutta S; Fukuda, Keisuke; Vogel, Edward K; Park, Sohee

2012-01-01

Although impairments in working memory (WM) are well documented in schizophrenia, the specific factors that cause these deficits are poorly understood. In this study, we hypothesized that a heightened susceptibility to attentional capture at an early stage of visual processing would result in working memory encoding problems. 30 patients with schizophrenia and 28 demographically matched healthy participants were presented with a search array and asked to report the orientation of the target stimulus. In some of the trials, a flanker stimulus preceded the search array that either matched the color of the target (relevant-flanker capture) or appeared in a different color (irrelevant-flanker capture). Working memory capacity was determined in each individual using the visual change detection paradigm. Patients needed considerably more time to find the target in the no-flanker condition. After adjusting the individual exposure time, both groups showed equivalent capture costs in the irrelevant-flanker condition. However, in the relevant-flanker condition, capture costs were increased in patients compared to controls when the stimulus onset asynchrony between the flanker and the search array was high. Moreover, the increase in relevant capture costs correlated negatively with working memory capacity. This study demonstrates preserved stimulus-driven attentional capture but impaired contingent attentional capture associated with low working memory capacity in schizophrenia. These findings suggest a selective impairment of top-down attentional control in schizophrenia, which may impair working memory encoding.

Synchronization to auditory and visual rhythms in hearing and deaf individuals

PubMed Central

Iversen, John R.; Patel, Aniruddh D.; Nicodemus, Brenda; Emmorey, Karen

2014-01-01

A striking asymmetry in human sensorimotor processing is that humans synchronize movements to rhythmic sound with far greater precision than to temporally equivalent visual stimuli (e.g., to an auditory vs. a flashing visual metronome). Traditionally, this finding is thought to reflect a fundamental difference in auditory vs. visual processing, i.e., superior temporal processing by the auditory system and/or privileged coupling between the auditory and motor systems. It is unclear whether this asymmetry is an inevitable consequence of brain organization or whether it can be modified (or even eliminated) by stimulus characteristics or by experience. With respect to stimulus characteristics, we found that a moving, colliding visual stimulus (a silent image of a bouncing ball with a distinct collision point on the floor) was able to drive synchronization nearly as accurately as sound in hearing participants. To study the role of experience, we compared synchronization to flashing metronomes in hearing and profoundly deaf individuals. Deaf individuals performed better than hearing individuals when synchronizing with visual flashes, suggesting that cross-modal plasticity enhances the ability to synchronize with temporally discrete visual stimuli. Furthermore, when deaf (but not hearing) individuals synchronized with the bouncing ball, their tapping patterns suggest that visual timing may access higher-order beat perception mechanisms for deaf individuals. These results indicate that the auditory advantage in rhythmic synchronization is more experience- and stimulus-dependent than has been previously reported. PMID:25460395

The Role of Multiple-Exemplar Training and Naming in Establishing Derived Equivalence in an Infant

PubMed Central

Luciano, Carmen; Becerra, Inmaculada Gómez; Valverde, Miguel Rodríguez

2007-01-01

The conditions under which symmetry and equivalence relations develop are still controversial. This paper reports three experiments that attempt to analyze the impact of multiple-exemplar training (MET) in receptive symmetry on the emergence of visual–visual equivalence relations with a very young child, Gloria. At the age of 15 months 24 days (15m24d), Gloria was tested for receptive symmetry and naming and showed no evidence of either repertoire. In the first experiment, MET in immediate and delayed receptive symmetrical responding or listener behavior (from object–sound to immediate and delayed sound–object selection) proceeded for one month with 10 different objects. This was followed, at 16m25d, by a second test conducted with six new objects. Gloria showed generalized receptive symmetry with a 3-hr delay; however no evidence of naming with new objects was found. Experiment 2 began at 17m with the aim of establishing derived visual–visual equivalence relations using a matching-to-sample format with two comparisons. Visual–visual equivalence responding emerged at 19m, although Gloria still had not shown evidence of naming. Experiment 3 (22m to 23m25d) used a three-comparison matching-to-sample procedure to establish visual–visual equivalence. Equivalence responding emerged as in Experiment 2, and naming emerged by the end of Experiment 3. Results are discussed in terms of the history of training in bidirectional relations responsible for the emergence of visual–visual equivalence relations and of their implications for current theories of stimulus equivalence. PMID:17575901

Non-native Speech Perception Training Using Vowel Subsets: Effects of Vowels in Sets and Order of Training

PubMed Central

Nishi, Kanae; Kewley-Port, Diane

2008-01-01

Purpose Nishi and Kewley-Port (2007) trained Japanese listeners to perceive nine American English monophthongs and showed that a protocol using all nine vowels (fullset) produced better results than the one using only the three more difficult vowels (subset). The present study extended the target population to Koreans and examined whether protocols combining the two stimulus sets would provide more effective training. Method Three groups of five Korean listeners were trained on American English vowels for nine days using one of the three protocols: fullset only, first three days on subset then six days on fullset, or first six days on fullset then three days on subset. Participants' performance was assessed by pre- and post-training tests, as well as by a mid-training test. Results 1) Fullset training was also effective for Koreans; 2) no advantage was found for the two combined protocols over the fullset only protocol, and 3) sustained “non-improvement” was observed for training using one of the combined protocols. Conclusions In using subsets for training American English vowels, care should be taken not only in the selection of subset vowels, but also for the training orders of subsets. PMID:18664694

Flow-mediated Dilation: Can New Approaches Provide Greater Mechanistic Insight into Vascular Dysfunction in Preeclampsia and Other Diseases?

PubMed Central

Weissgerber, Tracey L.

2015-01-01

Endothelial dysfunction is a key feature of preeclampsia, and may contribute to increased cardiovascular disease risk years after pregnancy. Flow-mediated dilation (FMD) is a non-invasive endothelial function test that predicts cardiovascular event risk. New protocols allow researchers to measure three components of the FMD response: FMD, low flow-mediated constriction and the shear stimulus. This review encourages researchers to think beyond “low FMD” by examining how these three components may provide additional insights into the mechanisms and location of vascular dysfunction. The review then examines what FMD studies reveal about vascular dysfunction in preeclampsia, while highlighting opportunities to gain greater mechanistic insight from new protocols. Studies using traditional protocols show that FMD is low in mid-pregnancy prior to preeclampsia, at diagnosis, and for three years post-partum. However, FMD returns to normal by ten years post-partum. Studies using new protocols are needed to gain more mechanistic insight. PMID:25182159

Flow-mediated dilation: can new approaches provide greater mechanistic insight into vascular dysfunction in preeclampsia and other diseases?

PubMed

Weissgerber, Tracey L

2014-11-01

Endothelial dysfunction is a key feature of preeclampsia and may contribute to increased cardiovascular disease risk years after pregnancy. Flow-mediated dilation (FMD) is a non-invasive endothelial function test that predicts cardiovascular event risk. New protocols allow researchers to measure three components of the FMD response: FMD, low flow-mediated constriction, and shear stimulus. This review encourages researchers to think beyond "low FMD" by examining how these three components may provide additional insights into the mechanisms and location of vascular dysfunction. The review then examines what FMD studies reveal about vascular dysfunction in preeclampsia while highlighting opportunities to gain greater mechanistic insight from new protocols. Studies using traditional protocols show that FMD is low in mid-pregnancy prior to preeclampsia, at diagnosis, and for 3 years post-partum. However, FMD returns to normal by 10 years post-partum. Studies using new protocols are needed to gain more mechanistic insight.

Correlating Whole Brain Neural Activity with Behavior in Head-Fixed Larval Zebrafish.

PubMed

Orger, Michael B; Portugues, Ruben

2016-01-01

We present a protocol to combine behavioral recording and imaging using 2-photon laser-scanning microscopy in head-fixed larval zebrafish that express a genetically encoded calcium indicator. The steps involve restraining the larva in agarose, setting up optics that allow projection of a visual stimulus and infrared illumination to monitor behavior, and analysis of the neuronal and behavioral data.

MEthods of ASsessing blood pressUre: identifying thReshold and target valuEs (MeasureBP): a review & study protocol.

PubMed

Blom, Kimberly C; Farina, Sasha; Gomez, Yessica-Haydee; Campbell, Norm R C; Hemmelgarn, Brenda R; Cloutier, Lyne; McKay, Donald W; Dawes, Martin; Tobe, Sheldon W; Bolli, Peter; Gelfer, Mark; McLean, Donna; Bartlett, Gillian; Joseph, Lawrence; Featherstone, Robin; Schiffrin, Ernesto L; Daskalopoulou, Stella S

2015-04-01

Despite progress in automated blood pressure measurement (BPM) technology, there is limited research linking hard outcomes to automated office BPM (OBPM) treatment targets and thresholds. Equivalences for automated BPM devices have been estimated from approximations of standardized manual measurements of 140/90 mmHg. Until outcome-driven targets and thresholds become available for automated measurement methods, deriving evidence-based equivalences between automated methods and standardized manual OBPM is the next best solution. The MeasureBP study group was initiated by the Canadian Hypertension Education Program to close this critical knowledge gap. MeasureBP aims to define evidence-based equivalent values between standardized manual OBPM and automated BPM methods by synthesizing available evidence using a systematic review and individual subject-level data meta-analyses. This manuscript provides a review of the literature and MeasureBP study protocol. These results will lay the evidenced-based foundation to resolve uncertainties within blood pressure guidelines which, in turn, will improve the management of hypertension.

Considerable contribution of the Montreal Protocol to declining greenhouse gas emissions from the United States

NASA Astrophysics Data System (ADS)

Hu, Lei; Montzka, Stephen A.; Lehman, Scott J.; Godwin, David S.; Miller, Benjamin R.; Andrews, Arlyn E.; Thoning, Kirk; Miller, John B.; Sweeney, Colm; Siso, Caroline; Elkins, James W.; Hall, Bradley D.; Mondeel, Debra J.; Nance, David; Nehrkorn, Thomas; Mountain, Marikate; Fischer, Marc L.; Biraud, Sébastien C.; Chen, Huilin; Tans, Pieter P.

2017-08-01

Ozone depleting substances (ODSs) controlled by the Montreal Protocol are potent greenhouse gases (GHGs), as are their substitutes, the hydrofluorocarbons (HFCs). Here we provide for the first time a comprehensive estimate of U.S. emissions of ODSs and HFCs based on precise measurements in discrete air samples from across North America and in the remote atmosphere. Derived emissions show spatial and seasonal variations qualitatively consistent with known uses and largely confirm U.S. Environmental Protection Agency (EPA) national emissions inventories for most gases. The measurement-based results further indicate a substantial decline of ODS emissions from 2008 to 2014, equivalent to 50% of the CO2-equivalent decline in combined emissions of CO2 and all other long-lived GHGs inventoried by the EPA for the same period. Total estimated CO2-equivalent emissions of HFCs were comparable to the sum of ODS emissions in 2014, but can be expected to decline in the future in response to recent policy measures.

Using heteroaryl-lithium reagents as hydroxycarbonyl anion equivalents in conjugate addition reactions with (S,S)-(+)-pseudoephedrine as chiral auxiliary; enantioselective synthesis of 3-substituted pyrrolidines.

PubMed

Alonso, Beatriz; Ocejo, Marta; Carrillo, Luisa; Vicario, Jose L; Reyes, Efraim; Uria, Uxue

2013-01-18

We have developed an efficient protocol for carrying out the stereocontrolled formal conjugate addition of hydroxycarbonyl anion equivalents to α,β-unsaturated carboxylic acid derivatives using (S,S)-(+)-pseudoephedrine as chiral auxiliary, making use of the synthetic equivalence between the heteroaryl moieties and the carboxylate group. This protocol has been applied as key step in the enantioselective synthesis of 3-substituted pyrrolidines in which, after removing the chiral auxiliary, the heteroaryl moiety is converted into a carboxylate group followed by reduction and double nucleophilic displacement. Alternatively, the access to the same type of heterocyclic scaffold but with opposite absolute configuration has also been accomplished by making use of the regio- and diastereoselective conjugate addition of organolithium reagents to α,β,γ,δ-unsaturated amides derived from the same chiral auxiliary followed by chiral auxiliary removal, ozonolysis, and reductive amination/intramolecular nucleophilic displacement sequence.

Effective radiation dose of ProMax 3D cone-beam computerized tomography scanner with different dental protocols.

PubMed

Qu, Xing-min; Li, Gang; Ludlow, John B; Zhang, Zu-yan; Ma, Xu-chen

2010-12-01

The aim of this study was to compare effective doses resulting from different scan protocols for cone-beam computerized tomography (CBCT) using International Commission on Radiological Protection (ICRP) 1990 and 2007 calculations of dose. Average tissue-absorbed dose, equivalent dose, and effective dose for a ProMax 3D CBCT with different dental protocols were calculated using thermoluminescent dosimeter chips in a human equivalent phantom. Effective doses were derived using ICRP 1990 and the superseding 2007 recommendations. Effective doses (ICRP 2007) for default patient sizes from small to large ranged from 102 to 298 μSv. The coefficient of determination (R(2)) between tube current and effective dose (ICRP 2007) was 0.90. When scanning with lower resolution settings, the effective doses were reduced significantly (P < .05). ProMax 3D can provide a wide range of radiation dose levels. Reduction in radiation dose can be achieved when using lower settings of exposure parameters. Copyright © 2010 Mosby, Inc. All rights reserved.

Effect of modulated ultrasound parameters on ultrasound-induced thrombolysis.

PubMed

Soltani, Azita; Volz, Kim R; Hansmann, Doulas R

2008-12-07

The potential of ultrasound to enhance enzyme-mediated thrombolysis by application of constant operating parameters (COP) has been widely demonstrated. In this study, the effect of ultrasound with modulated operating parameters (MOP) on enzyme-mediated thrombolysis was investigated. The MOP protocol was applied to an in vitro model of thrombolysis. The results were compared to a COP with the equivalent soft tissue thermal index (TIS) over the duration of ultrasound exposure of 30 min (p < 0.14). To explore potential differences in the mechanism responsible for ultrasound-induced thrombolysis, a perfusion model was used to measure changes in average fibrin pore size of clot before, after and during exposure to MOP and COP protocols and cavitational activity was monitored in real time for both protocols using a passive cavitation detection system. The relative lysis enhancement by each COP and MOP protocol compared to alteplase alone yielded values of 33.69 +/- 12.09% and 63.89 +/- 15.02% in a thrombolysis model, respectively (p < 0.007). Both COP and MOP protocols caused an equivalent significant increase in average clot pore size of 2.09 x 10(-2) +/- 0.01 microm and 1.99 x 10(-2) +/- 0.004 microm, respectively (p < 0.74). No signatures of inertial or stable cavitation were observed for either acoustic protocol. In conclusion, due to mechanisms other than cavitation, application of ultrasound with modulated operating parameters has the potential to significantly enhance the relative lysis enhancement compared to application of ultrasound with constant operating parameters.

Insecurity of Wireless Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheldon, Frederick T; Weber, John Mark; Yoo, Seong-Moo

Wireless is a powerful core technology enabling our global digital infrastructure. Wi-Fi networks are susceptible to attacks on Wired Equivalency Privacy, Wi-Fi Protected Access (WPA), and WPA2. These attack signatures can be profiled into a system that defends against such attacks on the basis of their inherent characteristics. Wi-Fi is the standard protocol for wireless networks used extensively in US critical infrastructures. Since the Wired Equivalency Privacy (WEP) security protocol was broken, the Wi-Fi Protected Access (WPA) protocol has been considered the secure alternative compatible with hardware developed for WEP. However, in November 2008, researchers developed an attack on WPA,more » allowing forgery of Address Resolution Protocol (ARP) packets. Subsequent enhancements have enabled ARP poisoning, cryptosystem denial of service, and man-in-the-middle attacks. Open source systems and methods (OSSM) have long been used to secure networks against such attacks. This article reviews OSSMs and the results of experimental attacks on WPA. These experiments re-created current attacks in a laboratory setting, recording both wired and wireless traffic. The article discusses methods of intrusion detection and prevention in the context of cyber physical protection of critical Internet infrastructure. The basis for this research is a specialized (and undoubtedly incomplete) taxonomy of Wi-Fi attacks and their adaptations to existing countermeasures and protocol revisions. Ultimately, this article aims to provide a clearer picture of how and why wireless protection protocols and encryption must achieve a more scientific basis for detecting and preventing such attacks.« less

Comparison of low- and ultralow-dose computed tomography protocols for quantitative lung and airway assessment.

PubMed

Hammond, Emily; Sloan, Chelsea; Newell, John D; Sieren, Jered P; Saylor, Melissa; Vidal, Craig; Hogue, Shayna; De Stefano, Frank; Sieren, Alexa; Hoffman, Eric A; Sieren, Jessica C

2017-09-01

Quantitative computed tomography (CT) measures are increasingly being developed and used to characterize lung disease. With recent advances in CT technologies, we sought to evaluate the quantitative accuracy of lung imaging at low- and ultralow-radiation doses with the use of iterative reconstruction (IR), tube current modulation (TCM), and spectral shaping. We investigated the effect of five independent CT protocols reconstructed with IR on quantitative airway measures and global lung measures using an in vivo large animal model as a human subject surrogate. A control protocol was chosen (NIH-SPIROMICS + TCM) and five independent protocols investigating TCM, low- and ultralow-radiation dose, and spectral shaping. For all scans, quantitative global parenchymal measurements (mean, median and standard deviation of the parenchymal HU, along with measures of emphysema) and global airway measurements (number of segmented airways and pi10) were generated. In addition, selected individual airway measurements (minor and major inner diameter, wall thickness, inner and outer area, inner and outer perimeter, wall area fraction, and inner equivalent circle diameter) were evaluated. Comparisons were made between control and target protocols using difference and repeatability measures. Estimated CT volume dose index (CTDIvol) across all protocols ranged from 7.32 mGy to 0.32 mGy. Low- and ultralow-dose protocols required more manual editing and resolved fewer airway branches; yet, comparable pi10 whole lung measures were observed across all protocols. Similar trends in acquired parenchymal and airway measurements were observed across all protocols, with increased measurement differences using the ultralow-dose protocols. However, for small airways (1.9 ± 0.2 mm) and medium airways (5.7 ± 0.4 mm), the measurement differences across all protocols were comparable to the control protocol repeatability across breath holds. Diameters, wall thickness, wall area fraction, and equivalent diameter had smaller measurement differences than area and perimeter measurements. In conclusion, the use of IR with low- and ultralow-dose CT protocols with CT volume dose indices down to 0.32 mGy maintains selected quantitative parenchymal and airway measurements relevant to pulmonary disease characterization. © 2017 American Association of Physicists in Medicine.

Comparisons of transient evoked otoacoustic emissions using chirp and click stimuli

PubMed Central

Keefe, Douglas H.; Feeney, M. Patrick; Hunter, Lisa L.; Fitzpatrick, Denis F.

2016-01-01

Transient-evoked otoacoustic emission (TEOAE) responses (0.7–8 kHz) were measured in normal-hearing adult ears using click stimuli and chirps whose local frequency increased or decreased linearly with time over the stimulus duration. Chirp stimuli were created by allpass filtering a click with relatively constant incident pressure level over frequency. Chirp TEOAEs were analyzed as a nonlinear residual signal by inverse allpass filtering each chirp response into an equivalent click response. Multi-window spectral and temporal averaging reduced noise levels compared to a single-window average. Mean TEOAE levels using click and chirp stimuli were similar with respect to their standard errors in adult ears. TEOAE group delay, group spread, instantaneous frequency, and instantaneous bandwidth were similar overall for chirp and click conditions, except for small differences showing nonlinear interactions differing across stimulus conditions. These results support the theory of a similar generation mechanism on the basilar membrane for both click and chirp conditions based on coherent reflection within the tonotopic region. TEOAE temporal fine structure was invariant across changes in stimulus level, which is analogous to the intensity invariance of click-evoked basilar-membrane displacement data. PMID:27914441

The continuous Wagon Wheel Illusion depends on, but is not identical to neuronal adaptation.

PubMed

VanRullen, Rufin

2007-07-01

The occurrence of perceived reversed motion while observers view a continuous, periodically moving stimulus (a bistable phenomenon coined the "continuous Wagon Wheel Illusion" or "c-WWI") has been taken as evidence that some aspects of motion perception rely on discrete sampling of visual information. Alternative accounts rely on the possibility of a motion aftereffect that may become visible even while the adapting stimulus is present. Here I show that motion adaptation might be necessary, but is not sufficient to explain the illusion. When local adaptation is prevented by slowly drifting the moving wheel across the retina, the c-WWI illusion tends to decrease, as do other bistable percepts (e.g. binocular rivalry). However, the strength of the c-WWI and that of adaptation (as measured by either the static or flicker motion aftereffects) are not directly related: although the c-WWI decreases with increasing eccentricity, the aftereffects actually intensify concurrently. A similar dissociation can be induced by manipulating stimulus contrast. This indicates that the c-WWI may be enabled by, but is not equivalent to, local motion adaptation - and that other factors such as discrete sampling may be involved in its generation.

Comparison of nine methods to estimate ear-canal stimulus levels

PubMed Central

Souza, Natalie N.; Dhar, Sumitrajit; Neely, Stephen T.; Siegel, Jonathan H.

2014-01-01

The reliability of nine measures of the stimulus level in the human ear canal was compared by measuring the sensitivity of behavioral hearing thresholds to changes in the depth of insertion of an otoacoustic emission probe. Four measures were the ear-canal pressure, the eardrum pressure estimated from it and the pressure measured in an ear simulator with and without compensation for insertion depth. The remaining five quantities were derived from the ear-canal pressure and the Thévenin-equivalent source characteristics of the probe: Forward pressure, initial forward pressure, the pressure transmitted into the middle ear, eardrum sound pressure estimated by summing the magnitudes of the forward and reverse pressure (integrated pressure) and absorbed power. Two sets of behavioral thresholds were measured in 26 subjects from 0.125 to 20 kHz, with the probe inserted at relatively deep and shallow positions in the ear canal. The greatest dependence on insertion depth was for transmitted pressure and absorbed power. The measures with the least dependence on insertion depth throughout the frequency range (best performance) included the depth-compensated simulator, eardrum, forward, and integrated pressures. Among these, forward pressure is advantageous because it quantifies stimulus phase. PMID:25324079

Endogenous pyrogen production by human blood monocytes stimulated by staphylococcal cell wall components.

PubMed

Oken, M M; Peterson, P K; Wilkinson, B J

1981-01-01

To determine the properties of Staphylococcus aureus contributing to its pyrogenicity, we compared, in human monocytes, endogenous pyrogen production stimulated by heat-killed S. aureus with that stimulated by purified S. aureus cell walls or by particulate peptidoglycan prepared from the same strain. Peptidoglycan, but not the purified cell wall preparation, was found comparable to S. aureus as an endogenous pyrogen stimulus. This finding was associated with a more effective monocyte phagocytosis of S. aureus and peptidoglycan as compared with that of purified cell walls. Lysostaphin digestion of peptidoglycan markedly reduced its pyrogenicity. To test whether the chemical composition of the ingested particles is important, latex particles were tested as possible stimuli for monocyte endogenous pyrogen release. Although 40 to 68% of monocytes ingested latex particles during the first hour, there was no evidence of endogenous pyrogen activity in the supernatant even when supernatants equivalent to 5.2 X 10(6) monocytes were tested. This study demonstrates that the pyrogenic moiety of the S. aureus cell wall resides in the peptidoglycan component. Phagocytosis is not in itself a pyrogenic stimulus, but rather serves as an effective mechanism to bring about contact between the chemical stimulus and the monocyte.

Comparisons of transient evoked otoacoustic emissions using chirp and click stimuli.

PubMed

Keefe, Douglas H; Feeney, M Patrick; Hunter, Lisa L; Fitzpatrick, Denis F

2016-09-01

Transient-evoked otoacoustic emission (TEOAE) responses (0.7-8 kHz) were measured in normal-hearing adult ears using click stimuli and chirps whose local frequency increased or decreased linearly with time over the stimulus duration. Chirp stimuli were created by allpass filtering a click with relatively constant incident pressure level over frequency. Chirp TEOAEs were analyzed as a nonlinear residual signal by inverse allpass filtering each chirp response into an equivalent click response. Multi-window spectral and temporal averaging reduced noise levels compared to a single-window average. Mean TEOAE levels using click and chirp stimuli were similar with respect to their standard errors in adult ears. TEOAE group delay, group spread, instantaneous frequency, and instantaneous bandwidth were similar overall for chirp and click conditions, except for small differences showing nonlinear interactions differing across stimulus conditions. These results support the theory of a similar generation mechanism on the basilar membrane for both click and chirp conditions based on coherent reflection within the tonotopic region. TEOAE temporal fine structure was invariant across changes in stimulus level, which is analogous to the intensity invariance of click-evoked basilar-membrane displacement data.

Comparing Web, Group and Telehealth Formats of a Military Parenting Program

DTIC Science & Technology

2017-06-01

directed approaches. Comparative effectiveness will be tested by specifying a non - equivalence hypothesis for group -based and web-facilitated relative...Comparative effectiveness will be tested by specifying a non - equivalence hypothesis fro group based and individualized facilitated relative to self-directed...documents for review and approval. 1a. Finalize human subjects protocol and consent documents for pilot group (N=5 families), and randomized controlled

Visual statistical learning is not reliably modulated by selective attention to isolated events

PubMed Central

Musz, Elizabeth; Weber, Matthew J.; Thompson-Schill, Sharon L.

2014-01-01

Recent studies of visual statistical learning (VSL) indicate that the visual system can automatically extract temporal and spatial relationships between objects. We report several attempts to replicate and extend earlier work (Turk-Browne et al., 2005) in which observers performed a cover task on one of two interleaved stimulus sets, resulting in learning of temporal relationships that occur in the attended stream, but not those present in the unattended stream. Across four experiments, we exposed observers to a similar or identical familiarization protocol, directing attention to one of two interleaved stimulus sets; afterward, we assessed VSL efficacy for both sets using either implicit response-time measures or explicit familiarity judgments. In line with prior work, we observe learning for the attended stimulus set. However, unlike previous reports, we also observe learning for the unattended stimulus set. When instructed to selectively attend to only one of the stimulus sets and ignore the other set, observers could extract temporal regularities for both sets. Our efforts to experimentally decrease this effect by changing the cover task (Experiment 1) or the complexity of the statistical regularities (Experiment 3) were unsuccessful. A fourth experiment using a different assessment of learning likewise failed to show an attentional effect. Simulations drawing random samples our first three experiments (n=64) confirm that the distribution of attentional effects in our sample closely approximates the null. We offer several potential explanations for our failure to replicate earlier findings, and discuss how our results suggest limiting conditions on the relevance of attention to VSL. PMID:25172196

Thermally assisted OSL application for equivalent dose estimation; comparison of multiple equivalent dose values as well as saturation levels determined by luminescence and ESR techniques for a sedimentary sample collected from a fault gouge

NASA Astrophysics Data System (ADS)

Şahiner, Eren; Meriç, Niyazi; Polymeris, George S.

2017-02-01

Equivalent dose estimation (De) constitutes the most important part of either trap-charge dating techniques or dosimetry applications. In the present work, multiple, independent equivalent dose estimation approaches were adopted, using both luminescence and ESR techniques; two different minerals were studied, namely quartz as well as feldspathic polymineral samples. The work is divided into three independent parts, depending on the type of signal employed. Firstly, different De estimation approaches were carried out on both polymineral and contaminated quartz, using single aliquot regenerative dose protocols employing conventional OSL and IRSL signals, acquired at different temperatures. Secondly, ESR equivalent dose estimations using the additive dose procedure both at room temperature and at 90 K were discussed. Lastly, for the first time in the literature, a single aliquot regenerative protocol employing a thermally assisted OSL signal originating from Very Deep Traps was applied for natural minerals. Rejection criteria such as recycling and recovery ratios are also presented. The SAR protocol, whenever applied, provided with compatible De estimations with great accuracy, independent on either the type of mineral or the stimulation temperature. Low temperature ESR signals resulting from Al and Ti centers indicate very large De values due to bleaching in-ability, associated with large uncertainty values. Additionally, dose saturation of different approaches was investigated. For the signal arising from Very Deep Traps in quartz saturation is extended almost by one order of magnitude. It is interesting that most of De values yielded using different luminescence signals agree with each other and ESR Ge center has very large D0 values. The results presented above highly support the argument that the stability and the initial ESR signal of the Ge center is highly sample-dependent, without any instability problems for the cases of quartz resulting from fault gouge.

Recording evoked potentials during deep brain stimulation: development and validation of instrumentation to suppress the stimulus artefact.

PubMed

Kent, A R; Grill, W M

2012-06-01

The clinical efficacy of deep brain stimulation (DBS) for the treatment of movement disorders depends on the identification of appropriate stimulation parameters. Since the mechanisms of action of DBS remain unclear, programming sessions can be time consuming, costly and result in sub-optimal outcomes. Measurement of electrically evoked compound action potentials (ECAPs) during DBS, generated by activated neurons in the vicinity of the stimulating electrode, could offer insight into the type and spatial extent of neural element activation and provide a potential feedback signal for the rational selection of stimulation parameters and closed-loop DBS. However, recording ECAPs presents a significant technical challenge due to the large stimulus artefact, which can saturate recording amplifiers and distort short latency ECAP signals. We developed DBS-ECAP recording instrumentation combining commercial amplifiers and circuit elements in a serial configuration to reduce the stimulus artefact and enable high fidelity recording. We used an electrical circuit equivalent model of the instrumentation to understand better the sources of the stimulus artefact and the mechanisms of artefact reduction by the circuit elements. In vitro testing validated the capability of the instrumentation to suppress the stimulus artefact and increase gain by a factor of 1000 to 5000 compared to a conventional biopotential amplifier. The distortion of mock ECAP (mECAP) signals was measured across stimulation parameters, and the instrumentation enabled high fidelity recording of mECAPs with latencies of only 0.5 ms for DBS pulse widths of 50 to 100 µs/phase. Subsequently, the instrumentation was used to record in vivo ECAPs, without contamination by the stimulus artefact, during thalamic DBS in an anesthetized cat. The characteristics of the physiological ECAP were dependent on stimulation parameters. The novel instrumentation enables high fidelity ECAP recording and advances the potential use of the ECAP as a feedback signal for the tuning of DBS parameters.

Learning to inhibit the response during instrumental (operant) extinction.

PubMed

Bouton, Mark E; Trask, Sydney; Carranza-Jasso, Rodrigo

2016-07-01

Five experiments tested implications of the idea that instrumental (operant) extinction involves learning to inhibit the learned response. All experiments used a discriminated operant procedure in which rats were reinforced for lever pressing or chain pulling in the presence of a discriminative stimulus (S), but not in its absence. In Experiment 1, extinction of the response (R) in the presence of S weakened responding in S, but equivalent nonreinforced exposure to S (without the opportunity to make R) did not. Experiment 2 replicated that result and found that extinction of R had no effect on a different R that had also been reinforced in the stimulus. In Experiments 3 and 4, rats first learned to perform several different stimulus and response combinations (S1R1, S2R1, S3R2, and S4R2). Extinction of a response in one stimulus (i.e., S1R1) transferred and weakened the same response, but not a different response, when it was tested in another stimulus (i.e., S2R1 but not S3R2). In Experiment 5, extinction still transferred between S1 and S2 when the stimuli set the occasion for R's association with different types of food pellets. The results confirm the importance of response inhibition in instrumental extinction: Nonreinforcement of the response in S causes the most effective suppression of responding, and response suppression is specific to the response but transfers and influences performance of the same response when it is occasioned by other stimuli. Theoretical and practical implications are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Behavioral Responses of Odontocetes to Playback of Anthropogenic and Natural Sounds

DTIC Science & Technology

2011-09-30

risk. Conservation Ecology 6(1):11 Ford JKB. 1989. Acoustic behavior of resident killer whales (Orcinus orca) off Vancouver Island, British...to natural sounds such as those from killer whales ; and to measure exposure parameters for sounds that evoke a behavioral response. APPROACH The...overall timing and bandwidth similar to the MFA stimulus, and recorded calls of killer whales (ORCA). The protocol put the highest priority on

Equivalence and test-retest reproducibility of conventional and extended-high-frequency audiometric thresholds obtained using pure-tone and narrow-band-noise stimuli.

PubMed

John, Andrew B; Kreisman, Brian M

2017-09-01

Extended high-frequency (EHF) audiometry is useful for evaluating ototoxic exposures and may relate to speech recognition, localisation and hearing aid benefit. There is a need to determine whether common clinical practice for EHF audiometry using tone and noise stimuli is reliable. We evaluated equivalence and compared test-retest (TRT) reproducibility for audiometric thresholds obtained using pure tones and narrowband noise (NBN) from 0.25 to 16 kHz. Thresholds and test-retest reproducibility for stimuli in the conventional (0.25-6 kHz) and EHF (8-16 kHz) frequency ranges were compared in a repeated-measures design. A total of 70 ears of adults with normal hearing. Thresholds obtained using NBN were significantly lower than thresholds obtained using pure tones from 0.5 to 16 kHz, but not 0.25 kHz. Good TRT reproducibility (within 2 dB) was observed for both stimuli at all frequencies. Responses at the lower limit of the presentation range for NBN centred at 14 and 16 kHz suggest unreliability for NBN as a threshold stimulus at these frequencies. Thresholds in the conventional and EHF ranges showed good test-retest reproducibility, but differed between stimulus types. Care should be taken when comparing pure-tone thresholds with NBN thresholds especially at these frequencies.

Words putting pain in motion: the generalization of pain-related fear within an artificial stimulus category

PubMed Central

Bennett, Marc P.; Meulders, Ann; Baeyens, Frank; Vlaeyen, Johan W. S.

2015-01-01

Patients with chronic pain are often fearful of movements that never featured in painful episodes. This study examined whether a neutral movement’s conceptual relationship with pain-relevant stimuli could precipitate pain-related fear; a process known as symbolic generalization. As a secondary objective, we also compared experiential and verbal fear learning in the generalization of pain-related fear. We conducted an experimental study with 80 healthy participants who were recruited through an online experimental management system (Mage = 23.04 years, SD = 6.80 years). First, two artificial categories were established wherein nonsense words and joystick arm movements were equivalent. Using a between-groups design, nonsense words from one category were paired with either an electrocutaneous stimulus (pain-US) or threatening information, while nonsense words from the other category were paired with no pain-US or safety information. During a final testing phase, participants were prompted to perform specific joystick arm movements that were never followed by a pain-US, although they were informed that it could occur. The results showed that movements equivalent to the pain-relevant nonsense words evoked heightened pain-related fear as measured by pain-US expectancy, fear of pain, and unpleasantness ratings. Also, experience with the pain-US evinced stronger acquisition and generalization compared to experience with threatening information. The clinical importance and theoretical implications of these findings are discussed. PMID:25983704

The dose-response relationship for hypoxic pulmonary vasoconstriction.

PubMed

Marshall, B E; Clarke, W R; Costarino, A T; Chen, L; Miller, F; Marshall, C

1994-05-01

In 12 pentobarbital anesthetized dogs the lungs were independently ventilated with a double piston ventilator. The right lung was ventilated throughout with 100% oxygen. Blood was drawn from the right atrium and pumped through a bubble oxygenator to a cannula in the ligated left main pulmonary artery. The pressures in the left main pulmonary artery and the left atrium were recorded during constant flow while the oxygen tension in the left lung alveolar gas and the perfusate were varied either to match each other (Protocol 1) or differ (Protocol 2) over the range from "zero" to "100%" oxygen. From the combined data a three dimensional response surface for hypoxic pulmonary vasoconstriction was derived. The maximum increase of pulmonary vascular resistance (r%PVRmax) was defined at a stimulus oxygen tension (PSO2) of 10 mmHg amounting to a 3.15 +/- (0.18)-fold increase of the vascular resistance on "100%" oxygen. The stimulus oxygen tension was shown to be PSO2 = PVO2(0.41) x PAO2(0.59) and the dose-response sigmoid for hypoxic pulmonary vasoconstriction in canine lungs was derived as r%PVRmax = 100 (PSO2(-2.616))/(6.683 x 10(-5) + PSO2(-2.616)) These results appear to reconcile observations from a number of laboratories and to be of quite general application.

The Status of Rapid Response Learning in Aging

PubMed Central

Dew, Ilana T. Z.; Giovanello, Kelly S.

2010-01-01

Strong evidence exists for an age-related impairment in associative processing under intentional encoding and retrieval conditions, but the status of incidental associative processing has been less clear. Two experiments examined the effects of age on rapid response learning – the incidentally learned stimulus-response association that results in a reduction in priming when a learned response becomes inappropriate for a new task. Specifically, we tested whether priming was equivalently sensitive in both age groups to reversing the task-specific decision cue. Experiment 1 showed that cue inversion reduced priming in both age groups using a speeded inside/outside classification task, and in Experiment 2 cue inversion eliminated priming on an associative version of this task. Thus, the ability to encode an association between a stimulus and its initial task-specific response appears to be preserved in aging. These findings provide an important example of a form of associative processing that is unimpaired in older adults. PMID:20853961

Olfactory memory formation and the influence of reward pathway during appetitive learning by honey bees.

PubMed

Wright, Geraldine A; Mustard, Julie A; Kottcamp, Sonya M; Smith, Brian H

2007-11-01

Animals possess the ability to assess food quality via taste and via changes in state that occur after ingestion. Here, we investigate the extent to which a honey bee's ability to assess food quality affected the formation of association with an odor stimulus and the retention of olfactory memories associated with reward. We used three different conditioning protocols in which the unconditioned stimulus (food) was delivered as sucrose stimulation to the proboscis (mouthparts), the antennae or to both proboscis and antennae. All means of delivery of the unconditioned stimulus produced robust associative conditioning with an odor. However, the memory of a conditioned odor decayed at a significantly greater rate for subjects experiencing antennal-only stimulation after either multiple- or single-trial conditioning. Finally, to test whether the act of feeding on a reward containing sucrose during conditioning affected olfactory memory formation, we conditioned honey bees to associate an odor with antennal stimulation with sucrose followed by feeding on a water droplet. We observed that a honey bee's ability to recall the conditioned odor was not significantly different from that of subjects conditioned with an antennal-only sucrose stimulus. Our results show that stimulation of the sensory receptors on the proboscis and/or ingestion of the sucrose reward during appetitive olfactory conditioning are necessary for long-term memory formation.

Pulser: user-friendly, graphical user-interface based software for controlling stimuli during data acquisition with Spike2 for Windows.

PubMed

Lidierth, Malcolm

2005-02-15

This paper describes software that runs in the Spike2 for Windows environment and provides a versatile tool for generating stimuli during data acquisition from the 1401 family of interfaces (CED, UK). A graphical user interface (GUI) is used to provide dynamic control of stimulus timing. Both single stimuli and trains of stimuli can be generated. The pulse generation routines make use of programmable variables within the interface and allow these to be rapidly changed during an experiment. The routines therefore provide the ease-of-use associated with external, stand-alone pulse generators. Complex stimulus protocols can be loaded from an external text file and facilities are included to create these files through the GUI. The software consists of a Spike2 script that runs in the host PC, and accompanying routines written in the 1401 sequencer control code, that run in the 1401 interface. Handshaking between the PC and the interface card are built into the routines and provides for full integration of sampling, analysis and stimulus generation during an experiment. Control of the 1401 digital-to-analogue converters is also provided; this allows control of stimulus amplitude as well as timing and also provides a sample-hold feature that may be used to remove DC offsets and drift from recorded data.

Quantitative PCR and Digital PCR for Detection of Ascaris lumbricoides Eggs in Reclaimed Water

PubMed Central

Santísima-Trinidad, Ana Belén; Bornay-Llinares, Fernando Jorge; Martín González, Marcos; Pascual Valero, José Antonio; Ros Muñoz, Margarita

2017-01-01

The reuse of reclaimed water from wastewater depuration is a widespread and necessary practice in many areas around the world and must be accompanied by adequate and continuous quality control. Ascaris lumbricoides is one of the soil-transmitted helminths (STH) with risk for humans due to its high infectivity and an important determinant of transmission is the inadequacy of water supplies and sanitation. The World Health Organization (WHO) recommends a limit equal to or lower than one parasitic helminth egg per liter, to reuse reclaimed water for unrestricted irrigation. We present two new protocols of DNA extraction from large volumes of reclaimed water. Quantitative PCR (qPCR) and digital PCR (dPCR) were able to detect low amounts of A. lumbricoides eggs. By using the first extraction protocol, which processes 500 mL of reclaimed water, qPCR can detect DNA concentrations as low as one A. lumbricoides egg equivalent, while dPCR can detect DNA concentrations as low as five A. lumbricoides egg equivalents. By using the second protocol, which processes 10 L of reclaimed water, qPCR was able to detect DNA concentrations equivalent to 20 A. lumbricoides eggs. This fact indicated the importance of developing new methodologies to detect helminth eggs with higher sensitivity and precision avoiding possible human infection risks. PMID:28377928

The difference between “equivalent” and “not different”

DOE PAGES

Anderson-Cook, Christine M.; Borror, Connie M.

2015-10-27

Often, experimenters wish to establish that populations of units can be considered equivalent to each other, in order to leverage improved knowledge about one population for characterizing the new population, or to establish the comparability of items. Equivalence tests have existed for many years, but their use in industry seems to have been largely restricted to biomedical applications, such as for assessing the equivalence of two drugs or protocols. We present the fundamentals of equivalence tests, compare them to traditional two-sample and ANOVA tests that are better suited to establishing differences in populations, and propose the use of a graphicalmore » summary to compare p-values across different thresholds of practically important differences.« less

Dual-layer DECT for multiphasic hepatic CT with 50 percent iodine load: a matched-pair comparison with a 120 kVp protocol.

PubMed

Nagayama, Yasunori; Nakaura, Takeshi; Oda, Seitaro; Utsunomiya, Daisuke; Funama, Yoshinori; Iyama, Yuji; Taguchi, Narumi; Namimoto, Tomohiro; Yuki, Hideaki; Kidoh, Masafumi; Hirata, Kenichiro; Nakagawa, Masataka; Yamashita, Yasuyuki

2018-04-01

To evaluate the image quality and lesion conspicuity of virtual-monochromatic-imaging (VMI) with dual-layer DECT (DL-DECT) for reduced-iodine-load multiphasic-hepatic CT. Forty-five adults with renal dysfunction who had undergone hepatic DL-DECT with 300-mgI/kg were included. VMI (40-70-keV, DL-DECT-VMI) was generated at each enhancement phase. As controls, 45 matched patients undergoing standard 120-kVp protocol (120-kVp, 600-mgI/kg, and iterative reconstruction) were included. We compared the size-specific dose estimate (SSDE), image noise, CT attenuation, and contrast-to-noise ratio (CNR) between protocols. Two radiologists scored the image quality and lesion conspicuity. SSDE was significantly lower in DL-DECT group (p < 0.01). Image noise of DL-DECT-VMI was almost constant at each keV (differences of ≤15%) and equivalent to or lower than of 120-kVp. As the energy decreased, CT attenuation and CNR gradually increased; the values of 55-60 keV images were almost equivalent to those of standard 120-kVp. The highest scores for overall quality and lesion conspicuity were assigned at 40-keV followed by 45 to 55-keV, all of which were similar to or better than of 120-kVp. For multiphasic-hepatic CT with 50% iodine-load, DL-DECT-VMI at 40- to 55-keV provides equivalent or better image quality and lesion conspicuity without increasing radiation dose compared with standard 120-kVp protocol. • 40-55-keV yields optimal image quality for half-iodine-load multiphasic-hepatic CT with DL-DECT. • DL-DECT protocol decreases radiation exposure compared with 120-kVp scans with iterative reconstruction. • 40-keV images maximise conspicuity of hepatocellular carcinoma especially at hepatic-arterial phase.

Beyond bipolar conceptualizations and measures: the case of attitudes and evaluative space.

PubMed

Cacioppo, J T; Gardner, W L; Berntson, G G

1997-01-01

All organisms must be capable of differentiating hostile from hospitable stimuli to survive. Typically, this evaluative discrimination is conceptualized as being bipolar (hostile-hospitable). This conceptualization is certainly evident in the area of attitudes, where the ubiquitous bipolar attitude measure, by gauging the net affective predisposition toward a stimulus, treats positive and negative evaluative processes as equivalent, reciprocally activated, and interchangeable. Contrary to conceptualizations of this evaluative process as bipolar, recent evidence suggests that distinguishable motivational systems underlie assessments of the positive and negative significance of a stimulus. Thus, a stimulus may vary in terms of the strength of positive evaluative activation and the strength of negative evaluative activation it evokes. Low activation of positive and negative evaluative processes by a stimulus reflects attitude neutrality or indifference, whereas high activation of positive and negative evaluative processes reflects attitude ambivalence. As such, attitudes can be represented more completely within a bivariate space than along a bipolar continuum. Evidence is reviewed showing that the positive and negative evaluative processes underlying many attitudes are distinguishable (stochastically and functionally independent), are characterized by distinct activation functions (positivity offset and negativity bias principles), are related differentially to attitude ambivalence (corollary of ambivalence asymmetries), have distinguishable antecedents (heteroscedacity principle), and tend to gravitate from a bivariate toward a bipolar structure when the underlying beliefs are the target of deliberation or a guide for behavior (principle of motivational certainty). The implications for society phenomena such as political elections and democratic structures are discussed.

Resetting of circadian melatonin and cortisol rhythms in humans by ordinary room light

NASA Technical Reports Server (NTRS)

Boivin, D. B.; Czeisler, C. A.

1998-01-01

The present study was designed to investigate whether a weak photic stimulus can reset the endogenous circadian rhythms of plasma melatonin and plasma cortisol in human subjects. A stimulus consisting of three cycles of 5 h exposures to ordinary room light (approximately 180 lux), centered 1.5 h after the endogenous temperature nadir, significantly phase-advanced the plasma melatonin rhythm in eight healthy young men compared with the phase delays observed in eight control subjects who underwent the same protocol but were exposed to darkness (p < or = 0.003). After light-induced phase advances, the circadian rhythms of plasma melatonin and plasma cortisol maintained stable temporal relationships with the endogenous core body temperature cycle, consistent with the conclusion that exposure to ordinary indoor room light had shifted a master circadian pacemaker.

Locomotion control of hybrid cockroach robots

PubMed Central

Sanchez, Carlos J.; Chiu, Chen-Wei; Zhou, Yan; González, Jorge M.; Vinson, S. Bradleigh; Liang, Hong

2015-01-01

Natural systems retain significant advantages over engineered systems in many aspects, including size and versatility. In this research, we develop a hybrid robotic system using American (Periplaneta americana) and discoid (Blaberus discoidalis) cockroaches that uses the natural locomotion and robustness of the insect. A tethered control system was firstly characterized using American cockroaches, wherein implanted electrodes were used to apply an electrical stimulus to the prothoracic ganglia. Using this approach, larger discoid cockroaches were engineered into a remotely controlled hybrid robotic system. Locomotion control was achieved through electrical stimulation of the prothoracic ganglia, via a remotely operated backpack system and implanted electrodes. The backpack consisted of a microcontroller with integrated transceiver protocol, and a rechargeable battery. The hybrid discoid roach was able to walk, and turn in response to an electrical stimulus to its nervous system with high repeatability of 60%. PMID:25740855

Does adopting a prenatal substance use protocol reduce racial disparities in CPS reporting related to maternal drug use? A California case study.

PubMed

Roberts, S C M; Zahnd, E; Sufrin, C; Armstrong, M A

2015-02-01

This study examined whether adopting a standardized prenatal substance use protocol (protocol) in a hospital labor and delivery unit reduced racial disparities in reporting to child protective services (CPS) related to maternal drug use during pregnancy. This study used an interrupted time series design with a non-equivalent control. One hospital adopted a protocol and another hospital group serving a similar geographic population did not change protocols. Data on CPS reporting disparities from these hospitals over 3.5 years were analyzed using segmented regression. In the hospital that adopted the protocol, almost five times more black than white newborns were reported during the study period. Adopting the protocol was not associated with reduced disparities. Adopting a protocol cannot be assumed to reduce CPS reporting disparities. Efforts to encourage hospitals to adopt protocols as a strategy to reduce disparities may be misguided. Other strategies to reduce disparities are needed.

Spontaneous Chronic Pain After Experimental Thoracotomy Revealed by Conditioned Place Preference: Morphine Differentiates Tactile Evoked Pain From Spontaneous Pain.

PubMed

Hung, Ching-Hsia; Wang, Jeffrey Chi-Fei; Strichartz, Gary R

2015-09-01

Chronic pain after surgery limits social activity, interferes with work, and causes emotional suffering. A major component of such pain is reported as resting or spontaneous pain with no apparent external stimulus. Although experimental animal models can simulate the stimulus-evoked chronic pain that occurs after surgery, there have been no studies of spontaneous chronic pain in such models. Here the conditioned place preference (CPP) paradigm was used to reveal resting pain after experimental thoracotomy. Male Sprague Dawley rats received a thoracotomy with 1-hour rib retraction, resulting in evoked tactile hypersensitivity, previously shown to last for at least 9 weeks. Intraperitoneal injections of morphine (2.5 mg/kg) or gabapentin (40 mg/kg) gave equivalent 2- to 3-hour-long relief of tactile hypersensitivity when tested 12 to 14 days postoperatively. In separate experiments, single trial CPP was conducted 1 week before thoracotomy and then 12 days (gabapentin) or 14 days (morphine) after surgery, followed the next day by 1 conditioning session with morphine or gabapentin, both versus saline. The gabapentin-conditioned but not the morphine-conditioned rats showed a significant preference for the analgesia-paired chamber, despite the equivalent effect of the 2 agents in relieving tactile allodynia. These results show that experimental thoracotomy in rats causes spontaneous pain and that some analgesics, such as morphine, that reduce evoked pain do not also relieve resting pain, suggesting that pathophysiological mechanisms differ between these 2 aspects of long-term postoperative pain. Perspective: Spontaneous pain, a hallmark of chronic postoperative pain, is demonstrated here in a rat model of experimental postthoracotomy pain, further validating the use of this model for the development of analgesics to treat such symptoms. Although stimulus-evoked pain was sensitive to systemic morphine, spontaneous pain was not, suggesting different mechanistic underpinnings. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

Normative Bilateral Brainstem Evoked Response Data for a Naval Aviation Student Population: Group Statistics

DTIC Science & Technology

1979-08-07

laus levels of the present study all fall within the plus and sinus one -standard deviation boundar; limits of the composite laboratory data plotted by...to be the case in the present study in that the =pz!Aude of the contralateral response prtduced by a given stimulus level follcuzd, in general, that...equivalent Gaussian distribution was applied to Cia study data. Such an analysis, performed by Thornton (36) on the latcncy and amplitude measurements

Spatial and Temporal Visual Masking and Visibility.

DTIC Science & Technology

1984-10-01

10x darker. Eutjects vie- d ’d binocularlI with free fi:aticn; heaa pcsiti:n was maintainel b -7 healrest The test stimulus was always a 4 fid vertical...In particular, our theoretical explanation (especially Birdsall’s Theorem) is in many ways equivalent to that presented by Lasley and Cohn b to...amplitude. In part A it it indicated that the width of the dark bars 901, BE) varies in different parts of the pattern. In part B is indicated tOe

Higher-order neural networks, Polyà polynomials, and Fermi cluster diagrams

NASA Astrophysics Data System (ADS)

Kürten, K. E.; Clark, J. W.

2003-09-01

The problem of controlling higher-order interactions in neural networks is addressed with techniques commonly applied in the cluster analysis of quantum many-particle systems. For multineuron synaptic weights chosen according to a straightforward extension of the standard Hebbian learning rule, we show that higher-order contributions to the stimulus felt by a given neuron can be readily evaluated via Polyà’s combinatoric group-theoretical approach or equivalently by exploiting a precise formal analogy with fermion diagrammatics.

Stress films, emotion, and cognitive response.

PubMed

Horowitz, M; Wilner, N

1976-11-01

The clinical theory of the repetition compulsion is sometimes taken to mean that neurotic persons, when traumatized, will develop compulsive repetitions of the trauma. Our experiment suggests that there is a more general effect--that various types of persons, after a variety of stressful events, will tend to develop intrusive and stimulus-repetitive thought; the stress itself does not necessarily have to have a negative valence. Equivalent effects were noted after stimuli that aroused positive emotions and after those stimuli that aroused dysphoric affects.

Patient Characterization Protocols for Psychophysiological Studies of Traumatic Brain Injury and Post-TBI Psychiatric Disorders

DTIC Science & Technology

2013-07-22

injury and psychiatric disorders are receiving increased research attention, and ERP technologies are making contributions to this effort. This review has... technology like ERPs. They yield information not evi- dent in RT and allow us to fractionate the stimulus input-response output process with greater...Homaifar et al. (98), who writing specifically about depression following TBI, recommended that multiple means of assessment should be used when diagnosing

Variation in diurnal sedation in mechanically ventilated patients who are managed with a sedation protocol alone or a sedation protocol and daily interruption.

PubMed

Mehta, Sangeeta; Meade, Maureen; Burry, Lisa; Mallick, Ranjeeta; Katsios, Christina; Fergusson, Dean; Dodek, Peter; Burns, Karen; Herridge, Margaret; Devlin, John W; Tanios, Maged; Fowler, Robert; Jacka, Michael; Skrobik, Yoanna; Olafson, Kendiss; Cook, Deborah

2016-08-01

Mechanically ventilated patients may receive more sedation during the night than during the day, potentially delaying extubation. We compared nighttime and daytime benzodiazepine and opioid administration in adult patients enrolled in a multicenter sedation trial comparing protocolized sedation alone or protocolized sedation combined with daily sedation interruption; and we evaluated whether nighttime and daytime doses were associated with liberation from mechanical ventilation. This is a secondary analysis of a randomized trial which was conducted in 16 North American medical-surgical ICUs. In all 423 patients, nurses applied a validated sedation scale hourly to titrate benzodiazepine and opioid infusions to achieve a light level of sedation. Using fentanyl equivalents and midazolam equivalents, we compared dosages administered during night (19:00 to 07:00) and day (07:00 to 19:00) shifts. Using multivariable logistic regression we evaluated the association between nighttime and daytime opioid and sedative doses, and spontaneous breathing trial (SBT) conduct, SBT success, and extubation. Nighttime benzodiazepine and opioid doses were significantly higher than daytime doses (mean difference midazolam equivalents 23.3 mg, 95 % CI 12.9, 33.8, p < 0.0001; mean difference fentanyl equivalents 356 mcg, 95 % CI 130, 582, p = 0.0021). Mean Sedation Agitation Scale score was similar between night and day, and was at target (3.2 vs 3.3, 95 % CI -0.05, 0.02, p = 0.35). Self-reported nurse workload was similar during the night and day. Patients were more often restrained during day shifts (76.3 % vs 73.7 %, p < 0.0001), and there were more unintentional device removals during the day compared with night (15.9 % vs 9.1 %, p < 0.0001). Increases in nighttime drug doses were independently associated with failure to meet SBT screening criteria, SBT failure, and the decision not to extubate the patient despite successful SBT. Patients received higher doses of opioids and benzodiazepines at night. Higher nighttime doses were associated with SBT failure and delayed extubation. ClinicalTrials.gov NCT00675363 . Registered 7 May 2008.

Sprayable microencapsulated sex pheromone formulations for mating disruption of four tortricid species: effects of application height, rate, frequency, and sticker adjuvant.

PubMed

Stelinski, L L; McGhee, P; Haas, M; Il'ichev, A L; Gut, L J

2007-08-01

Several application parameters of microencapsulated (MEC) sex pheromone formulations were manipulated to determine their impact on efficacy of disruption for codling moth, Cydia pomonella (L.); oriental fruit moth, Grapholita molesta (Busck); obliquebanded leafroller, Choristoneura rosaceana (Harris); and redbanded leafroller, Argyrotaenia velutinana (Walker). Depending on the experiment, the formulations evaluated were those formerly manufactured by 3M Canada (London, ON, Canada) or those that are currently available from Suterra LLC (Bend, OR). The efficacy of MEC formulations applied by air-blast sprayer evenly throughout the entire canopy of 2-3-m-tall apple (Malus spp.) trees was equivalent to treatments in which targeted applications of MECs were made to the lower or upper 1.5 m of the canopy (at equivalent overall rates) for oriental fruit moth and both leafroller species. The realized distribution of deposited microcapsules within the tree canopy corresponded well with the intended heights of application within the canopy. The additional coapplication of the pine resin sticker Nu-Film 17 increased efficacy but not longevity of MEC formulations for oriental fruit moth; this adjuvant had no added effects for codling moth or leafroller formulations. Increasing the rate of active ingredient (AI) per hectare by 20-30-fold (range 2.5-75.0 g/ha) did not improve the disruption efficacy of MECs for codling moth or either leafroller species when both low and high rates were applied at equivalent frequencies per season. A low-rate, high-frequency (nine applications per season) application protocol was compared with a standard protocol in which two to three applications were made per season, once before each moth generation for each species. The low-rate, high-frequency protocol resulted in equivalent or better disruption efficacy for each moth species, despite using two-fold less total AI per hectare per season with the former treatment. The low-rate, frequent-application protocol should make the use of MEC formulations of synthetic pheromone more economical and perhaps more effective.

Adaptive enhancement of learning protocol in hippocampal cultured networks grown on multielectrode arrays

PubMed Central

Pimashkin, Alexey; Gladkov, Arseniy; Mukhina, Irina; Kazantsev, Victor

2013-01-01

Learning in neuronal networks can be investigated using dissociated cultures on multielectrode arrays supplied with appropriate closed-loop stimulation. It was shown in previous studies that weakly respondent neurons on the electrodes can be trained to increase their evoked spiking rate within a predefined time window after the stimulus. Such neurons can be associated with weak synaptic connections in nearby culture network. The stimulation leads to the increase in the connectivity and in the response. However, it was not possible to perform the learning protocol for the neurons on electrodes with relatively strong synaptic inputs and responding at higher rates. We proposed an adaptive closed-loop stimulation protocol capable to achieve learning even for the highly respondent electrodes. It means that the culture network can reorganize appropriately its synaptic connectivity to generate a desired response. We introduced an adaptive reinforcement condition accounting for the response variability in control stimulation. It significantly enhanced the learning protocol to a large number of responding electrodes independently on its base response level. We also found that learning effect preserved after 4–6 h after training. PMID:23745105

Electroencephalographic reactivity testing in unconscious patients: a systematic review of methods and definitions.

PubMed

Admiraal, M M; van Rootselaar, A-F; Horn, J

2017-02-01

Electroencephalographic (EEG) reactivity testing is often presented as a clear-cut element of electrophysiological testing. Absence of EEG reactivity is generally considered an indicator of poor outcome, especially in patients after cardiac arrest. However, guidelines do not clearly describe how to test for reactivity and how to evaluate the results. In a quest for clear guidelines, we performed a systematic review aimed at identifying testing methods and definitions of EEG reactivity. We systematically searched the literature between 1970 and May 2016. Methodological quality of the studies was assessed using the QUality In Prognostic Studies tool. Quality of the descriptions of stimulus protocol and reactivity definition was rated on a four-category grading scale based on reproducibility. We found that protocols for EEG reactivity testing vary greatly and descriptions of protocols are almost never replicable. Furthermore, replicable definitions of presence or absence of EEG reactivity are never provided. In order to draw firm conclusions on EEG reactivity as a prognostic factor, future studies should include a precise stimulation protocol and reactivity definition to facilitate guideline formation. © 2016 EAN.

Measuring Changes in Ciliary Muscle Thickness with Accommodation in Young Adults

PubMed Central

Lossing, Laura Ashley; Sinnott, Loraine T.; Kao, Chiu-Yen; Richdale, Kathryn; Bailey, Melissa D.

2012-01-01

Purpose To develop a measurement protocol for changes in the shape and size of the ciliary muscle with accommodation using the Zeiss Visante™ Anterior Segment Optical Coherence Tomographer (AS-OCT) and to determine the test-retest repeatability of these measurements. Methods Subjects were 25 adults ages 23–28 years. The ciliary muscle was imaged at two visits with the Visante™ while accommodative response was monitored during imaging using the PowerRefractor. Ciliary muscle thickness was measured at 1 mm (CMT1), 2 mm (CMT2), and 3 mm (CMT3) posterior to the scleral spur and at the point of maximal thickness (CMTMAX). Thickness was measured at these locations while subjects viewed a target at distance and at a 4.00-D accommodative stimulus. Outcome measures were the change in thickness between distance and the 4.00-D stimulus and the change in thickness per diopter of accommodative response (PowerRefractor). Finally, the repeatability measurements between visit 1 and visit 2 were determined with a Bland-Altman analysis. Results The statistically significant modeled changes in ciliary muscle thickness were as follows: CMTMAX = 69.2 μm (4.00-D stimulus) and 18.1 μm (per diopter of accommodation); CMT1 = 45.2 μm (4.00-D stimulus) and 12.3 μm (per diopter of accommodation); and CMT3 = −45.9 μm (4.00-D stimulus) and −12.0 μm (per diopter of accommodation); p < 0.0001 for all. Conclusions The combination of the Visante™ and the PowerRefractor is a feasible tool for measuring thickening of ciliary muscle at more anterior locations and thinning at more posterior locations during accommodation. We noted a wide range of accommodative responses during the time of image capture in this study indicating that the most accurate estimates of the change in ciliary muscle dimensions with accommodation may be obtained by using accommodative response rather than stimulus values and by using measurements taken simultaneously with image capture. PMID:22504328

Encoding instructions and stimulus presentation in local environmental context-dependent memory studies.

PubMed

Markopoulos, G; Rutherford, A; Cairns, C; Green, J

2010-08-01

Murnane and Phelps (1993) recommend word pair presentations in local environmental context (EC) studies to prevent associations being formed between successively presented items and their ECs and a consequent reduction in the EC effect. Two experiments were conducted to assess the veracity of this assumption. In Experiment 1, participants memorised single words or word pairs, or categorised them as natural or man made. Their free recall protocols were examined to assess any associations established between successively presented items. Fewest associations were observed when the item-specific encoding task (i.e., natural or man made categorisation of word referents) was applied to single words. These findings were examined further in Experiment 2, where the influence of encoding instructions and stimulus presentation on local EC dependent recognition memory was examined. Consistent with recognition dual-process signal detection model predictions and findings (e.g., Macken, 2002; Parks & Yonelinas, 2008), recollection sensitivity, but not familiarity sensitivity, was found to be local EC dependent. However, local EC dependent recognition was observed only after item-specific encoding instructions, irrespective of stimulus presentation. These findings and the existing literature suggest that the use of single word presentations and item-specific encoding enhances local EC dependent recognition.

Interactions of cervico-ocular and vestibulo-ocular fast-phase signals in the control of eye position in rabbits.

PubMed Central

Barmack, N H; Errico, P; Ferraresi, A; Pettorossi, V E

1989-01-01

1. Eye movements in unanaesthetized rabbits were studied during horizontal neck-proprioceptive stimulation (movement of the body with respect to the fixed head), when this stimulation was given alone and when it was given simultaneously with vestibular stimulation (rotation of the head-body). The effect of neck-proprioceptive stimulation on modifying the anticompensatory fast-phase eye movements (AFPs) evoked by vestibular stimulation was studied with a 'conditioning-test' protocol; the 'conditioning' stimulus was a neck-proprioceptive signal evoked by a step-like change in body position with respect to the head and the 'test' stimulus was a vestibular signal evoked by a step rotation of the head-body. 2. The influence of eye position and direction of slow eye movements on the occurrence of compensatory fast-phase eye movements (CFPs) evoked by neck-proprioceptive stimulation was also examined. 3. The anticompensatory fast phase (AFP) evoked by vestibular stimulation was attenuated by a preceding neck-proprioceptive stimulus which when delivered alone evoked compensatory slow-phase eye movements (CSP) in the same direction as the CSP evoked by vestibular stimulation. Conversely, the vestibularly evoked AFP was potentiated by a neck-proprioceptive stimulus which evoked CSPs opposite to that of vestibularly evoked CSPs. 4. Eccentric initial eye positions increased the probability of occurrence of midline-directed compensatory fast-phase eye movements (CFPs) evoked by appropriate neck-proprioceptive stimulation. 5. The gain of the horizontal cervico-ocular reflex (GHCOR) was measured from the combined changes in eye position resulting from AFPs and CSPs. GHCOR was potentiated during simultaneous vestibular stimulation. This enhancement of GHCOR occurred at neck-proprioceptive stimulus frequencies which, in the absence of conjoint vestibular stimulation, do not evoke CSPs. PMID:2795479

Interoceptive conditioning in rats: effects of using a single training dose or a set of 5 different doses of nicotine.

PubMed

Pittenger, Steven T; Bevins, Rick A

2013-12-01

Interoceptive conditioning contributes to the tenacity of nicotine dependence. Previous research investigating nicotine as an interoceptive stimulus has typically employed administration of a single training dose of nicotine over an extended time. This approach has allowed for careful study of the nicotine stimulus. In humans, the nicotine stimulus is unlikely to be fixed across learning episodes. Thus, from a translational perspective, systematic variation of nicotine dose in training might better approximate interoceptive conditioning in humans. Notably, training with a class or set of discrete exteroceptive stimuli (e.g., different pictures of cars) produces interesting behavioral differences relative to training with a single stimulus. The present study sought to determine whether similar differences would occur if a set of nicotine stimuli were used in place of a single dose. To investigate this question, one group of male Sprague-Dawley rats was trained on a discriminated goal-tracking task with a set of nicotine doses (0.05, 0.125, 0.2, 0.275, and 0.35mg/kg). A second group received the standard protocol of training with a single nicotine dose (0.2mg/kg). On each nicotine session, there was intermittent access to liquid sucrose (26%) in a conditioning chamber. On intermixed saline sessions, sucrose was withheld. We examined acquisition, subsequent extinction, transfer of extinction, nicotine generalization, and mecamylamine blockade. Both groups reliably discriminated between nicotine and saline sessions, were sensitive to non-reinforcement, displayed transfer of extinction, demonstrated dose-dependent nicotine generalization, and responding was blocked by mecamylamine. There were no significant differences between the two groups. The unique nature of an interoceptive pharmacological stimulus and the challenges posed for studying the impact of training with a set of interoceptive stimuli are discussed. © 2013.

Recent Visual Experience Shapes Visual Processing in Rats through Stimulus-Specific Adaptation and Response Enhancement.

PubMed

Vinken, Kasper; Vogels, Rufin; Op de Beeck, Hans

2017-03-20

From an ecological point of view, it is generally suggested that the main goal of vision in rats and mice is navigation and (aerial) predator evasion [1-3]. The latter requires fast and accurate detection of a change in the visual environment. An outstanding question is whether there are mechanisms in the rodent visual system that would support and facilitate visual change detection. An experimental protocol frequently used to investigate change detection in humans is the oddball paradigm, in which a rare, unexpected stimulus is presented in a train of stimulus repetitions [4]. A popular "predictive coding" theory of cortical responses states that neural responses should decrease for expected sensory input and increase for unexpected input [5, 6]. Despite evidence for response suppression and enhancement in noninvasive scalp recordings in humans with this paradigm [7, 8], it has proven challenging to observe both phenomena in invasive action potential recordings in other animals [9-11]. During a visual oddball experiment, we recorded multi-unit spiking activity in rat primary visual cortex (V1) and latero-intermediate area (LI), which is a higher area of the rodent ventral visual stream. In rat V1, there was only evidence for response suppression related to stimulus-specific adaptation, and not for response enhancement. However, higher up in area LI, spiking activity showed clear surprise-based response enhancement in addition to stimulus-specific adaptation. These results show that neural responses along the rat ventral visual stream become increasingly sensitive to changes in the visual environment, suggesting a system specialized in the detection of unexpected events. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effects of whole body vibration on EMG activity of the upper extremity muscles in static modified push up position.

PubMed

Ashnagar, Zinat; Shadmehr, Azadeh; Hadian, Mohammadreza; Talebian, Saeed; Jalaei, Shohreh

2016-08-10

Whole Body Vibration (WBV) has been reported to change neuromuscular activity which indirectly assessed by electromyography (EMG). Although researches regarding the influence of WBV on EMG activity of the upper extremity muscles are in their infancy, contradictory findings have been reported as a result of dissimilar protocols. The purpose of this study was to investigate the effects of WBV on electromyography (EMG) activity of upper extremity muscles in static modified push up position. Forty recreationally active females were randomly assigned in WBV and control groups. Participants in WBV group received 5 sets of 30 seconds vibration at 5 mm (peak to peak) and 30 Hz by using vibratory platform. No vibration stimulus was used in the control group. Surface EMG was recorded from Upper Trapezius (UT), Serratus Anterior (SA), Biceps Brachii (BB) and Triceps Brachii (TB) muscles before, during and after the vibration protocol while the subjects maintained the static modified push up position. EMG signals were expressed as root mean square (EMGrms) and normalized by maximum voluntary exertion (MVE). EMGrms activity of the studied muscles increased significantly during the vibration protocol in the WBV group comparing to the control group (P ≤ 0.05). The results indicated that vibration stimulus transmitting via hands increased muscle activity of UT, SA, BB and TB muscles by an average of 206%, 60%, 106% and 120%, respectively, comparing to pre vibration values. These findings suggest that short exposure to the WBV could increase the EMGrms activity of the upper extremity muscles in the static modified push-up position. However, more sessions of WBV application require for a proper judgment.

Appetitive but not aversive olfactory conditioning modifies antennal movements in honeybees

PubMed Central

Cholé, Hanna; Junca, Pierre

2015-01-01

In honeybees, two olfactory conditioning protocols allow the study of appetitive and aversive Pavlovian associations. Appetitive conditioning of the proboscis extension response (PER) involves associating an odor, the conditioned stimulus (CS) with a sucrose solution, the unconditioned stimulus (US). Conversely, aversive conditioning of the sting extension response (SER) involves associating the odor CS with an electric or thermal shock US. Each protocol is based on the measure of a different behavioral response (proboscis versus sting) and both only provide binary responses (extension or not of the proboscis or sting). These limitations render the measure of the acquired valence of an odor CS difficult without testing the animals in a freely moving situation. Here, we studied the effects of both olfactory conditioning protocols on the movements of the antennae, which are crucial sensory organs for bees. As bees’ antennae are highly mobile, we asked whether their movements in response to an odorant change following appetitive or aversive conditioning and if so, do odor-evoked antennal movements contain information about the acquired valence of the CS? We implemented a tracking system for harnessed bees’ antennal movements based on a motion capture principle at a high frequency rate. We observed that differential appetitive conditioning had a strong effect on antennal movements. Bees responded to the reinforced odorant with a marked forward motion of the antennae and a strong velocity increase. Conversely, differential aversive conditioning had no associative effect on antennal movements. Rather than revealing the acquired valence of an odorant, antennal movements may represent a novel conditioned response taking place during appetitive conditioning and may provide a possible advantage to bees when foraging in natural situations. PMID:26572651

Effects of select and reject control on equivalence class formation and transfer of function.

PubMed

Perez, William F; Tomanari, Gerson Y; Vaidya, Manish

2015-09-01

The present study used a single-subject design to evaluate the effects of select or reject control on equivalence class formation and transfer of function. Adults were exposed to a matching-to-sample task with observing requirements (MTS-OR) in order to bias the establishment of sample/S+ (select) or sample/S- (reject) relations. In Experiment 1, four sets of baseline conditional relations were taught-two under reject control (A1B2C1, A2B1C2) and two under select control (D1E1F1, D2E2F2). Participants were tested for transitivity, symmetry, equivalence and reflexivity. They also learned a simple discrimination involving one of the stimuli from the equivalence classes and were tested for the transfer of the discriminative function. In general, participants performed with high accuracy on all equivalence-related probes as well as the transfer of function probes under select control. Under reject control, participants had high scores only on the symmetry test; transfer of function was attributed to stimuli programmed as S-. In Experiment 2, the equivalence class under reject control was expanded to four members (A1B2C1D2; A2B1C2D1). Participants had high scores only on symmetry and on transitivity and equivalence tests involving two nodes. Transfer of function was extended to the programmed S- added to each class. Results from both experiments suggest that select and reject controls might differently affect the formation of equivalence classes and the transfer of stimulus functions. © Society for the Experimental Analysis of Behavior.

Memory Meets Control in Hippocampal and Striatal Binding of Stimuli, Responses, and Attentional Control States

PubMed Central

Brashier, Nadia M.

2015-01-01

The human brain encodes experience in an integrative fashion by binding together the various features of an event (i.e., stimuli and responses) into memory “event files.” A subsequent reoccurrence of an event feature can then cue the retrieval of the memory file to “prime” cognition and action. Intriguingly, recent behavioral studies indicate that, in addition to linking concrete stimulus and response features, event coding may also incorporate more abstract, “internal” event features such as attentional control states. In the present study, we used fMRI in healthy human volunteers to determine the neural mechanisms supporting this type of holistic event binding. Specifically, we combined fMRI with a task protocol that dissociated the expression of event feature-binding effects pertaining to concrete stimulus and response features, stimulus categories, and attentional control demands. Using multivariate neural pattern classification, we show that the hippocampus and putamen integrate event attributes across all of these levels in conjunction with other regions representing concrete-feature-selective (primarily visual cortex), category-selective (posterior frontal cortex), and control demand-selective (insula, caudate, anterior cingulate, and parietal cortex) event information. Together, these results suggest that the hippocampus and putamen are involved in binding together holistic event memories that link physical stimulus and response characteristics with internal representations of stimulus categories and attentional control states. These bindings then presumably afford shortcuts to adaptive information processing and response selection in the face of recurring events. SIGNIFICANCE STATEMENT Memory binds together the different features of our experience, such as an observed stimulus and concurrent motor responses, into so-called event files. Recent behavioral studies suggest that the observer's internal attentional state might also become integrated into the event memory. Here, we used fMRI to determine the brain areas responsible for binding together event information pertaining to concrete stimulus and response features, stimulus categories, and internal attentional control states. We found that neural signals in the hippocampus and putamen contained information about all of these event attributes and could predict behavioral priming effects stemming from these features. Therefore, medial temporal lobe and dorsal striatum structures appear to be involved in binding internal control states to event memories. PMID:26538657

Psychological treatment of Comorbid Asthma and Panic Disorder: A Pilot Study

PubMed Central

Lehrer, Paul M.; Karavidas, Maria Katsamanis; Lu, Shou-En; Feldman, Jonathan; Kranitz, Linda; Abraham, Smrithy; Sanderson, William; Reynolds, Russ

2008-01-01

We evaluated two protocols for treating adults with comorbid asthma and panic disorder. The protocols included elements of Barlow’s “panic control therapy” and several asthma education programs, as well as modules designed to teach participants how to differentiate asthma and panic symptoms, and how to apply specific home management strategies for each. Fifty percent of subjects dropped out of a 14-session protocol by the eighth session; however, 83% of patients were retained in an eight-session protocol. Clinical results were mostly equivalent: significant decreases of >50% in panic symptoms, clinically significant decreases in asthma symptoms, improvement in asthma quality of life, and maintenance of clinical stability in asthma. Albuterol use decreased significantly in the 14-session protocol and at a borderline level in the 8-session protocol, while pulmonary function was maintained. A controlled evaluation of this procedure is warranted. PMID:17693054

Modeling depth from motion parallax with the motion/pursuit ratio

PubMed Central

Nawrot, Mark; Ratzlaff, Michael; Leonard, Zachary; Stroyan, Keith

2014-01-01

The perception of unambiguous scaled depth from motion parallax relies on both retinal image motion and an extra-retinal pursuit eye movement signal. The motion/pursuit ratio represents a dynamic geometric model linking these two proximal cues to the ratio of depth to viewing distance. An important step in understanding the visual mechanisms serving the perception of depth from motion parallax is to determine the relationship between these stimulus parameters and empirically determined perceived depth magnitude. Observers compared perceived depth magnitude of dynamic motion parallax stimuli to static binocular disparity comparison stimuli at three different viewing distances, in both head-moving and head-stationary conditions. A stereo-viewing system provided ocular separation for stereo stimuli and monocular viewing of parallax stimuli. For each motion parallax stimulus, a point of subjective equality (PSE) was estimated for the amount of binocular disparity that generates the equivalent magnitude of perceived depth from motion parallax. Similar to previous results, perceived depth from motion parallax had significant foreshortening. Head-moving conditions produced even greater foreshortening due to the differences in the compensatory eye movement signal. An empirical version of the motion/pursuit law, termed the empirical motion/pursuit ratio, which models perceived depth magnitude from these stimulus parameters, is proposed. PMID:25339926

Psychophysical testing of spatial and temporal dimensions of endogenous analgesia: conditioned pain modulation and offset analgesia.

PubMed

Honigman, Liat; Yarnitsky, David; Sprecher, Elliot; Weissman-Fogel, Irit

2013-08-01

The endogenous analgesia (EA) system is psychophysically evaluated using various paradigms, including conditioned pain modulation (CPM) and offset analgesia (OA) testing, respectively, the spatial and temporal filtering processes of noxious information. Though both paradigms assess the function of the EA system, it is still unknown whether they reflect the same aspects of EA and consequently whether they provide additive or equivalent data. Twenty-nine healthy volunteers (15 males) underwent 5 trials of different stimulation conditions in random order including: (1) the classic OA three-temperature stimulus train ('OA'); (2) a three-temperature stimulus train as control for the OA ('OAcon'); (3) a constant temperature stimulus ('constant'); (4) the classic parallel CPM ('CPM'); and (5) a combination of OA and CPM ('OA + CPM'). We found that in males, the pain reduction during the OA + CPM condition was greater than during the OA (P = 0.003) and CPM (P = 0.07) conditions. Furthermore, a correlation was found between OA and CPM (r = 0.62, P = 0.01) at the time of maximum OA effect. The additive effect found suggests that the two paradigms represent at least partially different aspects of EA. The moderate association between the CPM and OA magnitudes indicates, on the other hand, some commonality of their underlying mechanisms.

Anticipatory eye movements evoked after active following versus passive observation of a predictable motion stimulus.

PubMed

Burke, M R; Barnes, G R

2008-12-15

We used passive and active following of a predictable smooth pursuit stimulus in order to establish if predictive eye movement responses are equivalent under both passive and active conditions. The smooth pursuit stimulus was presented in pairs that were either 'predictable' in which both presentations were matched in timing and velocity, or 'randomized' in which each presentation in the pair was varied in both timing and velocity. A visual cue signaled the type of response required from the subject; a green cue indicated the subject should follow both the target presentations (Go-Go), a pink cue indicated that the subject should passively observe the 1st target and follow the 2nd target (NoGo-Go), and finally a green cue with a black cross revealed a randomized (Rnd) trial in which the subject should follow both presentations. The results revealed better prediction in the Go-Go trials than in the NoGo-Go trials, as indicated by higher anticipatory velocity and earlier eye movement onset (latency). We conclude that velocity and timing information stored from passive observation of a moving target is diminished when compared to active following of the target. This study has significant consequences for understanding how visuomotor memory is generated, stored and subsequently released from short-term memory.

Locomotion control of hybrid cockroach robots.

PubMed

Sanchez, Carlos J; Chiu, Chen-Wei; Zhou, Yan; González, Jorge M; Vinson, S Bradleigh; Liang, Hong

2015-04-06

Natural systems retain significant advantages over engineered systems in many aspects, including size and versatility. In this research, we develop a hybrid robotic system using American (Periplaneta americana) and discoid (Blaberus discoidalis) cockroaches that uses the natural locomotion and robustness of the insect. A tethered control system was firstly characterized using American cockroaches, wherein implanted electrodes were used to apply an electrical stimulus to the prothoracic ganglia. Using this approach, larger discoid cockroaches were engineered into a remotely controlled hybrid robotic system. Locomotion control was achieved through electrical stimulation of the prothoracic ganglia, via a remotely operated backpack system and implanted electrodes. The backpack consisted of a microcontroller with integrated transceiver protocol, and a rechargeable battery. The hybrid discoid roach was able to walk, and turn in response to an electrical stimulus to its nervous system with high repeatability of 60%. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Dynamic mapping of the human visual cortex by high-speed magnetic resonance imaging.

PubMed Central

Blamire, A M; Ogawa, S; Ugurbil, K; Rothman, D; McCarthy, G; Ellermann, J M; Hyder, F; Rattner, Z; Shulman, R G

1992-01-01

We report the use of high-speed magnetic resonance imaging to follow the changes in image intensity in the human visual cortex during stimulation by a flashing checkerboard stimulus. Measurements were made in a 2.1-T, 1-m-diameter magnet, part of a Bruker Biospec spectrometer that we had programmed to do echo-planar imaging. A 15-cm-diameter surface coil was used to transmit and receive signals. Images were acquired during periods of stimulation from 2 s to 180 s. Images were acquired in 65.5 ms in a 10-mm slice with in-plane voxel size of 6 x 3 mm. Repetition time (TR) was generally 2 s, although for the long flashing periods, TR = 8 s was used. Voxels were located onto an inversion recovery image taken with 2 x 2 mm in-plane resolution. Image intensity increased after onset of the stimulus. The mean change in signal relative to the prestimulation level (delta S/S) was 9.7% (SD = 2.8%, n = 20) with an echo time of 70 ms. Irrespective of the period of stimulation, the increase in magnetic resonance signal intensity was delayed relative to the stimulus. The mean delay measured from the start of stimulation for each protocol was as follows: 2-s stimulation, delay = 3.5 s (SD = 0.5 s, n = 10) (the delay exceeds stimulus duration); 20- to 24-s stimulation, delay = 5 s (SD = 2 s, n = 20). PMID:1438317

Catechol-O-methyltransferase (COMT) genotype affects cognitive control during total sleep deprivation.

PubMed

Satterfield, Brieann C; Hinson, John M; Whitney, Paul; Schmidt, Michelle A; Wisor, Jonathan P; Van Dongen, Hans P A

2018-02-01

Adaptive decision making is profoundly impaired by total sleep deprivation (TSD). This suggests that TSD impacts fronto-striatal pathways involved in cognitive control, where dopamine is a key neuromodulator. In the prefrontal cortex (PFC), dopamine is catabolized by the enzyme catechol-O-methyltransferase (COMT). A functional polymorphism (Val158Met) influences COMT's enzymatic activity, resulting in markedly different levels of prefrontal dopamine. We investigated the effect of this polymorphism on adaptive decision making during TSD. Sixty-six healthy young adults participated in one of two in-laboratory studies. After a baseline day, subjects were randomized to either a TSD group (n = 32) with 38 h or 62 h of extended wakefulness or a well-rested control group (n = 34) with 10 h nighttime sleep opportunities. Subjects performed a go/no-go reversal learning (GNGr) task at well-rested baseline and again during TSD or equivalent control. During the task, subjects were required to learn stimulus-response relationships from accuracy feedback. The stimulus-response relationships were reversed halfway through the task, which required subjects to learn the new stimulus-response relationships from accuracy feedback. Performance on the GNGr task was quantified by discriminability (d') between go and no-go stimuli before and after the stimulus-response reversal. GNGr performance did not differ between COMT genotypes when subjects were well-rested. However, TSD exposed a significant vulnerability to adaptive decision making impairment in subjects with the Val allele. Our results indicate that sleep deprivation degrades cognitive control through a fronto-striatal, dopaminergic mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.

Critical and maximally informative encoding between neural populations in the retina

PubMed Central

Kastner, David B.; Baccus, Stephen A.; Sharpee, Tatyana O.

2015-01-01

Computation in the brain involves multiple types of neurons, yet the organizing principles for how these neurons work together remain unclear. Information theory has offered explanations for how different types of neurons can maximize the transmitted information by encoding different stimulus features. However, recent experiments indicate that separate neuronal types exist that encode the same filtered version of the stimulus, but then the different cell types signal the presence of that stimulus feature with different thresholds. Here we show that the emergence of these neuronal types can be quantitatively described by the theory of transitions between different phases of matter. The two key parameters that control the separation of neurons into subclasses are the mean and standard deviation (SD) of noise affecting neural responses. The average noise across the neural population plays the role of temperature in the classic theory of phase transitions, whereas the SD is equivalent to pressure or magnetic field, in the case of liquid–gas and magnetic transitions, respectively. Our results account for properties of two recently discovered types of salamander Off retinal ganglion cells, as well as the absence of multiple types of On cells. We further show that, across visual stimulus contrasts, retinal circuits continued to operate near the critical point whose quantitative characteristics matched those expected near a liquid–gas critical point and described by the nearest-neighbor Ising model in three dimensions. By operating near a critical point, neural circuits can maximize information transmission in a given environment while retaining the ability to quickly adapt to a new environment. PMID:25675497

Physiological stimuli evoke two forms of endocytosis in bovine chromaffin cells.

PubMed

Chan, S A; Smith, C

2001-12-15

1. Exocytosis and endocytosis were measured following single, or trains of, simulated action potentials (sAP) in bovine adrenal chromaffin cells. Catecholamine secretion was measured by oxidative amperometry and cell membrane turnover was measured by voltage clamp cell capacitance measurements. 2. The sAPs evoked inward Na(+) and Ca(2+) currents that were statistically identical to those evoked by native action potential waveforms. On average, a single secretory granule underwent fusion following sAP stimulation. An equivalent amount of membrane was then quickly internalised (tau = 560 ms). 3. Stimulation with sAP trains revealed a biphasic relationship between cell firing rate and endocytic activity. At basal stimulus frequencies (single to 0.5 Hz) cells exhibited a robust membrane internalisation that then diminished as firing increased to intermediate levels (1.9 and 6 Hz). However at the higher stimulation rates (10 and 16 Hz) endocytic activity rebounded and was again able to effectively maintain cell surface near pre-stimulus levels. 4. Treatment with cyclosporin A and FK506, inhibitors of the phosphatase calcineurin, left endocytosis characteristics unaltered at the lower basal stimulus levels, but blocked the resurgence in endocytosis seen in control cells at higher sAP frequencies. 5. Based on these findings we propose that, under physiological electrical stimulation, chromaffin cells internalise membrane via two distinct pathways that are separable. One is prevalent at basal stimulus frequencies, is lessened with increased firing, and is insensitive to cyclosporin A and FK506. A second endocytic form is activated by increased firing frequencies, and is selectively blocked by cyclosporin A and FK506.

Physiological stimuli evoke two forms of endocytosis in bovine chromaffin cells

PubMed Central

Chan, Shyue-An; Smith, Corey

2001-01-01

Exocytosis and endocytosis were measured following single, or trains of, simulated action potentials (sAP) in bovine adrenal chromaffin cells. Catecholamine secretion was measured by oxidative amperometry and cell membrane turnover was measured by voltage clamp cell capacitance measurements. The sAPs evoked inward Na+ and Ca2+ currents that were statistically identical to those evoked by native action potential waveforms. On average, a single secretory granule underwent fusion following sAP stimulation. An equivalent amount of membrane was then quickly internalised (τ = 560 ms). Stimulation with sAP trains revealed a biphasic relationship between cell firing rate and endocytic activity. At basal stimulus frequencies (single to 0.5 Hz) cells exhibited a robust membrane internalisation that then diminished as firing increased to intermediate levels (1.9 and 6 Hz). However at the higher stimulation rates (10 and 16 Hz) endocytic activity rebounded and was again able to effectively maintain cell surface near pre-stimulus levels. Treatment with cyclosporin A and FK506, inhibitors of the phosphatase calcineurin, left endocytosis characteristics unaltered at the lower basal stimulus levels, but blocked the resurgence in endocytosis seen in control cells at higher sAP frequencies. Based on these findings we propose that, under physiological electrical stimulation, chromaffin cells internalise membrane via two distinct pathways that are separable. One is prevalent at basal stimulus frequencies, is lessened with increased firing, and is insensitive to cyclosporin A and FK506. A second endocytic form is activated by increased firing frequencies, and is selectively blocked by cyclosporin A and FK506. PMID:11744761

Stereomotion speed perception: contributions from both changing disparity and interocular velocity difference over a range of relative disparities

NASA Technical Reports Server (NTRS)

Brooks, Kevin R.; Stone, Leland S.

2004-01-01

The role of two binocular cues to motion in depth-changing disparity (CD) and interocular velocity difference (IOVD)- was investigated by measuring stereomotion speed discrimination and static disparity discrimination performance (stereoacuity). Speed discrimination thresholds were assessed both for random dot stereograms (RDS), and for their temporally uncorrelated equivalents, dynamic random dot stereograms (DRDS), at relative disparity pedestals of -19, 0, and +19 arcmin. While RDS stimuli contain both CD and IOVD cues, DRDS stimuli carry only CD information. On average, thresholds were a factor of 1.7 higher for DRDS than for RDS stimuli with no clear effect of relative disparity pedestal. Results were similar for approaching and receding targets. Variations in stimulus duration had no significant effect on thresholds, and there was no observed correlation between stimulus displacement and perceived speed, confirming that subjects responded to stimulus speed in each condition. Stereoacuity was equally good for our RDS and DRDS stimuli, showing that the difference in stereomotion speed discrimination performance for these stimuli was not due to any difference in the precision of the disparity cue. In addition, when we altered stereomotion stimulus trajectory by independently manipulating the speeds and directions of its monocular half-images, perceived stereomotion speed remained accurate. This finding is inconsistent with response strategies based on properties of either monocular half-image motion, or any ad hoc combination of the monocular speeds. We conclude that although subjects are able to discriminate stereomotion speed reliably on the basis of CD information alone, IOVD provides a precise additional cue to stereomotion speed perception.

Solid shape discrimination from vision and haptics: natural objects (Capsicum annuum) and Gibson's "feelies".

PubMed

Norman, J Farley; Phillips, Flip; Holmin, Jessica S; Norman, Hideko F; Beers, Amanda M; Boswell, Alexandria M; Cheeseman, Jacob R; Stethen, Angela G; Ronning, Cecilia

2012-10-01

A set of three experiments evaluated 96 participants' ability to visually and haptically discriminate solid object shape. In the past, some researchers have found haptic shape discrimination to be substantially inferior to visual shape discrimination, while other researchers have found haptics and vision to be essentially equivalent. A primary goal of the present study was to understand these discrepant past findings and to determine the true capabilities of the haptic system. All experiments used the same task (same vs. different shape discrimination) and stimulus objects (James Gibson's "feelies" and a set of naturally shaped objects--bell peppers). However, the methodology varied across experiments. Experiment 1 used random 3-dimensional (3-D) orientations of the stimulus objects, and the conditions were full-cue (active manipulation of objects and rotation of the visual objects in depth). Experiment 2 restricted the 3-D orientations of the stimulus objects and limited the haptic and visual information available to the participants. Experiment 3 compared restricted and full-cue conditions using random 3-D orientations. We replicated both previous findings in the current study. When we restricted visual and haptic information (and placed the stimulus objects in the same orientation on every trial), the participants' visual performance was superior to that obtained for haptics (replicating the earlier findings of Davidson et al. in Percept Psychophys 15(3):539-543, 1974). When the circumstances resembled those of ordinary life (e.g., participants able to actively manipulate objects and see them from a variety of perspectives), we found no significant difference between visual and haptic solid shape discrimination.

Biphasic and monophasic repair: comparative implications for biologically equivalent dose calculations in pulsed dose rate brachytherapy of cervical carcinoma

PubMed Central

Millar, W T; Davidson, S E

2013-01-01

Objective: To consider the implications of the use of biphasic rather than monophasic repair in calculations of biologically-equivalent doses for pulsed-dose-rate brachytherapy of cervix carcinoma. Methods: Calculations are presented of pulsed-dose-rate (PDR) doses equivalent to former low-dose-rate (LDR) doses, using biphasic vs monophasic repair kinetics, both for cervical carcinoma and for the organ at risk (OAR), namely the rectum. The linear-quadratic modelling calculations included effects due to varying the dose per PDR cycle, the dose reduction factor for the OAR compared with Point A, the repair kinetics and the source strength. Results: When using the recommended 1 Gy per hourly PDR cycle, different LDR-equivalent PDR rectal doses were calculated depending on the choice of monophasic or biphasic repair kinetics pertaining to the rodent central nervous and skin systems. These differences virtually disappeared when the dose per hourly cycle was increased to 1.7 Gy. This made the LDR-equivalent PDR doses more robust and independent of the choice of repair kinetics and α/β ratios as a consequence of the described concept of extended equivalence. Conclusion: The use of biphasic and monophasic repair kinetics for optimised modelling of the effects on the OAR in PDR brachytherapy suggests that an optimised PDR protocol with the dose per hourly cycle nearest to 1.7 Gy could be used. Hence, the durations of the new PDR treatments would be similar to those of the former LDR treatments and not longer as currently prescribed. Advances in knowledge: Modelling calculations indicate that equivalent PDR protocols can be developed which are less dependent on the different α/β ratios and monophasic/biphasic kinetics usually attributed to normal and tumour tissues for treatment of cervical carcinoma. PMID:23934965

For Your Phone Only: Custom Protocols for Efficient Secure Function Evaluation on Mobile Devices (Preprint)

DTIC Science & Technology

2012-11-01

that mobile application developers should reconsider implementing garbled circuits due to their extreme resource usage, and instead rely upon our equivalently secure and significantly more efficient alternative.

Current fluctuations in periodically driven systems

NASA Astrophysics Data System (ADS)

Barato, Andre C.; Chetrite, Raphael

2018-05-01

Small nonequelibrium systems driven by an external periodic protocol can be described by Markov processes with time-periodic transition rates. In general, current fluctuations in such small systems are large and may play a crucial role. We develop a theoretical formalism to evaluate the rate of such large deviations in periodically driven systems. We show that the scaled cumulant generating function that characterizes current fluctuations is given by a maximal Floquet exponent. Comparing deterministic protocols with stochastic protocols, we show that, with respect to large deviations, systems driven by a stochastic protocol with an infinitely large number of jumps are equivalent to systems driven by deterministic protocols. Our results are illustrated with three case studies: a two-state model for a heat engine, a three-state model for a molecular pump, and a biased random walk with a time-periodic affinity.

Neuroimaging paradigms for tonotopic mapping (II): the influence of acquisition protocol.

PubMed

Langers, Dave R M; Sanchez-Panchuelo, Rosa M; Francis, Susan T; Krumbholz, Katrin; Hall, Deborah A

2014-10-15

Numerous studies on the tonotopic organisation of auditory cortex in humans have employed a wide range of neuroimaging protocols to assess cortical frequency tuning. In the present functional magnetic resonance imaging (fMRI) study, we made a systematic comparison between acquisition protocols with variable levels of interference from acoustic scanner noise. Using sweep stimuli to evoke travelling waves of activation, we measured sound-evoked response signals using sparse, clustered, and continuous imaging protocols that were characterised by inter-scan intervals of 8.8, 2.2, or 0.0 s, respectively. With regard to sensitivity to sound-evoked activation, the sparse and clustered protocols performed similarly, and both detected more activation than the continuous method. Qualitatively, tonotopic maps in activated areas proved highly similar, in the sense that the overall pattern of tonotopic gradients was reproducible across all three protocols. However, quantitatively, we observed substantial reductions in response amplitudes to moderately low stimulus frequencies that coincided with regions of strong energy in the scanner noise spectrum for the clustered and continuous protocols compared to the sparse protocol. At the same time, extreme frequencies became over-represented for these two protocols, and high best frequencies became relatively more abundant. Our results indicate that although all three scanning protocols are suitable to determine the layout of tonotopic fields, an exact quantitative assessment of the representation of various sound frequencies is substantially confounded by the presence of scanner noise. In addition, we noticed anomalous signal dynamics in response to our travelling wave paradigm that suggest that the assessment of frequency-dependent tuning is non-trivially influenced by time-dependent (hemo)dynamics when using sweep stimuli. Copyright © 2014. Published by Elsevier Inc.

Bone loss during long term space flight is prevented by the application of a short term impulsive mechanical stimulus

NASA Astrophysics Data System (ADS)

Goodship, A. E.; Cunningham, J. L.; Oganov, V.; Darling, J.; Miles, A. W.; Owen, G. W.

In long term space flight, the mechanical forces applied to the skeleton are substantially reduced and are altered in character. This reduced skeletal loading results in a reduction in bone mass. Exercise techmques currently used in space can maintain muscle mass but the mechanical stimulus provided by this exercise does not prevent bone loss. By applying an external impulsive load for a short period each day, which is intended to mimic the heel strike transient, to the lower limb of an astronaut during a long term space flight (5 months), this study tests the hypothesis that the bone cells can be activated by an appropriate external mechanical stimulus to maintain bone mass throughout prolonged periods of weightlessness. A mechanical loading device was developed to produce a loading of the os-calcis similar to that observed during the heel strike transient. The device is activated by the astronaut to provide a transient load to the heel of one leg whilst providing an equivalent exercising load to the other leg. During the EUROMIR95 mission on the MIR space station, an astronaut used this device for a short period daily throughout the duration of the mission. Pre- and post-flight measurements of bone mineral density (BMD) of the os-calcis and femoral neck of the astronaut were made to determine the efficacy of the device in preventing loss of bone mineral during the mission. On the os-calcis which received the mechanical stimulus, BMD was maintained throughout the period of the flight, while it was reduced by up to 7% on the os-calcis which received no stimulus. Post-flight, BMD in both the stimulated and non-stimulated os-calcis reduces, the extent of this reduction however is less in the stimulated os-calcis. For the femoral neck, the mechanical Stimulation does not produce a positive effect. On the os-calcis which received the mechanical stimulus, BMD was maintained throughout the period of the flight, while it was reduced by up to 7% on the os-calcis which received no stimulus. Post-flight, BMD in both the stimulated and non-stimulated os-calcis reduces, the extent of this reduction however is less in the stimulated os-calcis. For the femoral neck, the mechanical stimulation does not produce a positive effect.

Visually induced adaptation in three-dimensional organization of primate vestibuloocular reflex

NASA Technical Reports Server (NTRS)

Angelaki, D. E.; Hess, B. J.

1998-01-01

The adaptive plasticity of the spatial organization of the vestibuloocular reflex (VOR) has been investigated in intact and canal-plugged primates using 2-h exposure to conflicting visual (optokinetic, OKN) and vestibular rotational stimuli about mutually orthogonal axes (generating torsional VOR + vertical OKN, torsional VOR + horizontal OKN, vertical VOR + horizontal OKN, and horizontal VOR + vertical OKN). Adaptation protocols with 0.5-Hz (+/-18 degrees ) head movements about either an earth-vertical or an earth-horizontal axis induced orthogonal response components as high as 40-70% of those required for ideal adaptation. Orthogonal response gains were highest at the adapting frequency with phase leads present at lower and phase lags present at higher frequencies. Furthermore, the time course of adaptation, as well as orthogonal response dynamics were similar and relatively independent of the particular visual/vestibular stimulus combination. Low-frequency (0. 05 Hz, vestibular stimulus: +/-60 degrees ; optokinetic stimulus: +/-180 degrees ) adaptation protocols with head movements about an earth-vertical axis induced smaller orthogonal response components that did not exceed 20-40% of the head velocity stimulus (i.e., approximately 10% of that required for ideal adaptation). At the same frequency, adaptation with head movements about an earth-horizontal axis generated large orthogonal responses that reached values as high as 100-120% of head velocity after 2 h of adaptation (i.e., approximately 40% of ideal adaptation gains). The particular spatial and temporal response characteristics after low-frequency, earth-horizontal axis adaptation in both intact and canal-plugged animals strongly suggests that the orienting (and perhaps translational) but not inertial (velocity storage) components of the primate otolith-ocular system exhibit spatial adaptability. Due to the particular nested arrangement of the visual and vestibular stimuli, the optic flow pattern exhibited a significant component about the third spatial axis (i.e., orthogonal to the axes of rotation of the head and visual surround) at twice the oscillation frequency. Accordingly, the adapted VOR was characterized consistently by a third response component (orthogonal to both the axes of head and optokinetic drum rotation) at twice the oscillation frequency after earth-horizontal but not after earth-vertical axis 0.05-Hz adaptation. This suggests that the otolith-ocular (but not the semicircular canal-ocular) system can adaptively change its spatial organization at frequencies different from those of the head movement.

Auditory cortical neurons are sensitive to static and continuously changing interaural phase cues.

PubMed

Reale, R A; Brugge, J F

1990-10-01

1. The interaural-phase-difference (IPD) sensitivity of single neurons in the primary auditory (AI) cortex of the anesthetized cat was studied at stimulus frequencies ranging from 120 to 2,500 Hz. Best frequencies of the 43 AI cells sensitive to IPD ranged from 190 to 2,400 Hz. 2. A static IPD was produced when a pair of low-frequency tone bursts, differing from one another only in starting phase, were presented dichotically. The resulting IPD-sensitivity curves, which plot the number of discharges evoked by the binaural signal as a function of IPD, were deeply modulated circular functions. IPD functions were analyzed for their mean vector length (r) and mean interaural phase (phi). Phase sensitivity was relatively independent of best frequency (BF) but highly dependent on stimulus frequency. Regardless of BF or stimulus frequency within the excitatory response area the majority of cells fired maximally when the ipsilateral tone lagged the contralateral signal and fired least when this interaural-phase relationship was reversed. 3. Sensitivity to continuously changing IPD was studied by delivering to the two ears 3-s tones that differed slightly in frequency, resulting in a binaural beat. Approximately 26% of the cells that showed a sensitivity to static changes in IPD also showed a sensitivity to dynamically changing IPD created by this binaural tonal combination. The discharges were highly periodic and tightly synchronized to a particular phase of the binaural beat cycle. High synchrony can be attributed to the fact that cortical neurons typically respond to an excitatory stimulus with but a single spike that is often precisely timed to stimulus onset. A period histogram, binned on the binaural beat frequency (fb), produced an equivalent IPD-sensitivity function for dynamically changing interaural phase. For neurons sensitive to both static and continuously changing interaural phase there was good correspondence between their static (phi s) and dynamic (phi d) mean interaural phases. 4. All cells responding to a dynamically changing stimulus exhibited a linear relationship between mean interaural phase and beat frequency. Most cells responded equally well to binaural beats regardless of the initial direction of phase change. For a fixed duration stimulus, and at relatively low fb, the number of spikes evoked increased with increasing fb, reflecting the increasing number of effective stimulus cycles. At higher fb, AI neurons were unable to follow the rate at which the most effective phase repeated itself during the 3 s of stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

IL-6, Antioxidant Capacity and Muscle Damage Markers Following High-Intensity Interval Training Protocols.

PubMed

Cipryan, Lukas

2017-02-01

The aim of this study was to investigate changes of interleukin-6 (IL-6), total antioxidant capacity (TAC) and muscle damage markers (creatine kinase (CK), myoglobin and lactate dehydrogenase (LDH)) in response to three different high-intensity interval training (HIIT) protocols of identical external work. Twelve moderately-trained males participated in the three HIIT trials which consisted of a warm-up, followed by 12 min of 15 s, 30 s or 60 s HIIT sequences with the work/rest ratio 1. The biochemical markers of inflammation, oxidative stress and muscle damage were analysed POST, 3 h and 24 h after the exercise. All HIIT protocols caused an immediate increase in IL-6, TAC, CK, myoglobin and LDH. The most pronounced between-trials differences were found for the POST-exercise changes in IL-6 (Effect size ± 90% confidence interval: 1.51 ± 0.63, 0.84 ± 0.34 and 1.80 ± 0.60 for the 15s/15s, 30s/30s and 60s/60s protocol, respectively) and myoglobin (1.11 ± 0.29, 0.45 ± 0.48 and 1.09 ± 0.22 for the 15s/15s, 30s/30s and 60s/60s protocol, respectively). There were no substantial between-trial differences in other biochemical variables. In conclusion, the 15s/15s and 60s/60s protocols might be preferred to the 30s/30s protocols in order to maximize the training stimulus.

Look before you leap: sensory memory improves decision making.

PubMed

Vlassova, Alexandra; Pearson, Joel

2013-09-01

Simple decisions require the processing and evaluation of perceptual and cognitive information, the formation of a decision, and often the execution of a motor response. This process involves the accumulation of evidence over time until a particular choice reaches a decision threshold. Using a random-dot-motion stimulus, we showed that simply delaying responses after the stimulus offset can almost double accuracy, even in the absence of new incoming visual information. However, under conditions in which the otherwise blank interval was filled with a sensory mask or concurrent working memory load was high, performance gains were lost. Further, memory and perception showed equivalent rates of evidence accumulation, suggesting a high-capacity memory store. We propose an account of continued evidence accumulation by sequential sampling from a simultaneously decaying memory trace. Memories typically decay with time, hence immediate inquiry trumps later recall from memory. However, the results we report here show the inverse: Inspecting a memory trumps viewing the actual object.

Size matters: Perceived depth magnitude varies with stimulus height.

PubMed

Tsirlin, Inna; Wilcox, Laurie M; Allison, Robert S

2016-06-01

Both the upper and lower disparity limits for stereopsis vary with the size of the targets. Recently, Tsirlin, Wilcox, and Allison (2012) suggested that perceived depth magnitude from stereopsis might also depend on the vertical extent of a stimulus. To test this hypothesis we compared apparent depth in small discs to depth in long bars with equivalent width and disparity. We used three estimation techniques: a virtual ruler, a touch-sensor (for haptic estimates) and a disparity probe. We found that depth estimates were significantly larger for the bar stimuli than for the disc stimuli for all methods of estimation and different configurations. In a second experiment, we measured perceived depth as a function of the height of the bar and the radius of the disc. Perceived depth increased with increasing bar height and disc radius suggesting that disparity is integrated along the vertical edges. We discuss size-disparity correlation and inter-neural excitatory connections as potential mechanisms that could account for these results. Copyright © 2016 Elsevier Ltd. All rights reserved.

Allocentrically implied target locations are updated in an eye-centred reference frame.

PubMed

Thompson, Aidan A; Glover, Christopher V; Henriques, Denise Y P

2012-04-18

When reaching to remembered target locations following an intervening eye movement a systematic pattern of error is found indicating eye-centred updating of visuospatial memory. Here we investigated if implicit targets, defined only by allocentric visual cues, are also updated in an eye-centred reference frame as explicit targets are. Participants viewed vertical bars separated by varying distances, and horizontal lines of equivalently varying lengths, implying a "target" location at the midpoint of the stimulus. After determining the implied "target" location from only the allocentric stimuli provided, participants saccaded to an eccentric location, and reached to the remembered "target" location. Irrespective of the type of stimulus reaching errors to these implicit targets are gaze-dependent, and do not differ from those found when reaching to remembered explicit targets. Implicit target locations are coded and updated as a function of relative gaze direction with respect to those implied locations just as explicit targets are, even though no target is specifically represented. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Factorizing the motion sensitivity function into equivalent input noise and calculation efficiency.

PubMed

Allard, Rémy; Arleo, Angelo

2017-01-01

The photopic motion sensitivity function of the energy-based motion system is band-pass peaking around 8 Hz. Using an external noise paradigm to factorize the sensitivity into equivalent input noise and calculation efficiency, the present study investigated if the variation in photopic motion sensitivity as a function of the temporal frequency is due to a variation of equivalent input noise (e.g., early temporal filtering) or calculation efficiency (ability to select and integrate motion). For various temporal frequencies, contrast thresholds for a direction discrimination task were measured in presence and absence of noise. Up to 15 Hz, the sensitivity variation was mainly due to a variation of equivalent input noise and little variation in calculation efficiency was observed. The sensitivity fall-off at very high temporal frequencies (from 15 to 30 Hz) was due to a combination of a drop of calculation efficiency and a rise of equivalent input noise. A control experiment in which an artificial temporal integration was applied to the stimulus showed that an early temporal filter (generally assumed to affect equivalent input noise, not calculation efficiency) could impair both the calculation efficiency and equivalent input noise at very high temporal frequencies. We conclude that at the photopic luminance intensity tested, the variation of motion sensitivity as a function of the temporal frequency was mainly due to early temporal filtering, not to the ability to select and integrate motion. More specifically, we conclude that photopic motion sensitivity at high temporal frequencies is limited by internal noise occurring after the transduction process (i.e., neural noise), not by quantal noise resulting from the probabilistic absorption of photons by the photoreceptors as previously suggested.

80-kVp CT Using Iterative Reconstruction in Image Space Algorithm for the Detection of Hypervascular Hepatocellular Carcinoma: Phantom and Initial Clinical Experience

PubMed Central

Hur, Saebeom; Kim, Soo Jin; Park, Ji Hoon; Han, Joon Koo; Choi, Byung Ihn

2012-01-01

Objective To investigate whether the low-tube-voltage (80-kVp), intermediate-tube-current (340-mAs) MDCT using the Iterative Reconstruction in Image Space (IRIS) algorithm improves lesion-to-liver contrast at reduced radiation dosage while maintaining acceptable image noise in the detection of hepatocellular carcinomas (HCC) in thin (mean body mass index, 24 ± 0.4 kg/m2) adults. Subjects and Methods A phantom simulating the liver with HCC was scanned at 50-400 mAs for 80, 100, 120 and 140-kVp. In addition, fifty patients with HCC who underwent multiphasic liver CT using dual-energy (80-kVp and 140-kVp) arterial scans were enrolled. Virtual 120-kVP scans (protocol A) and 80-kVp scans (protocol B) of the late arterial phase were reconstructed with filtered back-projection (FBP), while corresponding 80-kVp scans were reconstructed with IRIS (protocol C). Contrast-to-noise ratio (CNR) of HCCs and abdominal organs were assessed quantitatively, whereas lesion conspicuity, image noise, and overall image quality were assessed qualitatively. Results IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study. In the quantitative patient study, protocol C helped improve CNR by 51% and 172% than protocols A and B (p < 0.001), respectively, at equivalent radiation dosage. In the qualitative study, protocol C acquired the highest score for lesion conspicuity albeit with an inferior score to protocol A for overall image quality (p < 0.001). Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C. Conclusion CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP. PMID:22438682

Noisy processing and distillation of private quantum States.

PubMed

Renes, Joseph M; Smith, Graeme

2007-01-12

We provide a simple security proof for prepare and measure quantum key distribution protocols employing noisy processing and one-way postprocessing of the key. This is achieved by showing that the security of such a protocol is equivalent to that of an associated key distribution protocol in which, instead of the usual maximally entangled states, a more general private state is distilled. In addition to a more general target state, the usual entanglement distillation tools are employed (in particular, Calderbank-Shor-Steane-like codes), with the crucial difference that noisy processing allows some phase errors to be left uncorrected without compromising the privacy of the key.

Tomographic quantum cryptography: equivalence of quantum and classical key distillation.

PubMed

Bruss, Dagmar; Christandl, Matthias; Ekert, Artur; Englert, Berthold-Georg; Kaszlikowski, Dagomir; Macchiavello, Chiara

2003-08-29

The security of a cryptographic key that is generated by communication through a noisy quantum channel relies on the ability to distill a shorter secure key sequence from a longer insecure one. For an important class of protocols, which exploit tomographically complete measurements on entangled pairs of any dimension, we show that the noise threshold for classical advantage distillation is identical with the threshold for quantum entanglement distillation. As a consequence, the two distillation procedures are equivalent: neither offers a security advantage over the other.

Molecular cloning of Brevundimonas diminuta for efficacy assessment of reverse osmosis devices.

PubMed

Donofrio, Robert; Saha, Ratul; Bestervelt, Lori; Bagley, Susan

2012-06-01

Brevundimonas diminuta is the test organism specified in the United States Environmental Protection Agency's (USEPA) reverse osmosis (RO) treatment device verification protocol. As non-selective growth medium is employed, enumeration of B. diminuta may be impaired due to interference by indigenous heterotrophic bacteria. Thus the microbial removal capability of the filtration system may be incorrectly assessed. As these treatment devices are used in emergency situations, the health of the public could be compromised. The objective of this study was to develop selective approaches for enumerating viable B. diminuta in test water. Two molecular approaches were investigated: expression of a kanamycin resistance gene and expression of a fluorescent protein gene. The USEPA protocol specifies a 0.3 μm cell size, so the expression of the selective markers were assessed following growth on media designed to induce this small cell diameter. The kan(R) strain was demonstrated to be equivalent to the wild type in cell dimension and survival following exposure to the test water. The kan(R) strain showed equivalent performance to the wild type in the RO protocol indicating that it is a viable alternative surrogate. By utilizing this strain, a more accurate validation of the RO system can be achieved.

New perspectives on the auditory cortex: learning and memory.

PubMed

Weinberger, Norman M

2015-01-01

Primary ("early") sensory cortices have been viewed as stimulus analyzers devoid of function in learning, memory, and cognition. However, studies combining sensory neurophysiology and learning protocols have revealed that associative learning systematically modifies the encoding of stimulus dimensions in the primary auditory cortex (A1) to accentuate behaviorally important sounds. This "representational plasticity" (RP) is manifest at different levels. The sensitivity and selectivity of signal tones increase near threshold, tuning above threshold shifts toward the frequency of acoustic signals, and their area of representation can increase within the tonotopic map of A1. The magnitude of area gain encodes the level of behavioral stimulus importance and serves as a substrate of memory strength. RP has the same characteristics as behavioral memory: it is associative, specific, develops rapidly, consolidates, and can last indefinitely. Pairing tone with stimulation of the cholinergic nucleus basalis induces RP and implants specific behavioral memory, while directly increasing the representational area of a tone in A1 produces matching behavioral memory. Thus, RP satisfies key criteria for serving as a substrate of auditory memory. The findings suggest a basis for posttraumatic stress disorder in abnormally augmented cortical representations and emphasize the need for a new model of the cerebral cortex. © 2015 Elsevier B.V. All rights reserved.

What reaches the antenna? How to calibrate odor flux and ligand-receptor affinities.

PubMed

Andersson, Martin N; Schlyter, Fredrik; Hill, Sharon Rose; Dekker, Teun

2012-06-01

Physiological studies on olfaction frequently ignore the airborne quantities of stimuli reaching the sensory organ. We used a gas chromatography-calibrated photoionization detector to estimate quantities released from standard Pasteur pipette stimulus cartridges during repeated puffing of 27 compounds and verified how lack of quantification could obscure olfactory sensory neuron (OSN) affinities. Chemical structure of the stimulus, solvent, dose, storage condition, puff interval, and puff number all influenced airborne quantities. A model including boiling point and lipophilicity, but excluding vapor pressure, predicted airborne quantities from stimuli in paraffin oil on filter paper. We recorded OSN responses of Drosophila melanogaster, Ips typographus, and Culex quinquefasciatus, to known quantities of airborne stimuli. These demonstrate that inferred OSN tuning width, ligand affinity, and classification can be confounded and require stimulus quantification. Additionally, proper dose-response analysis shows that Drosophila AB3A OSNs are not promiscuous, but highly specific for ethyl hexanoate, with other earlier proposed ligands 10- to 10 000-fold less potent. Finally, we reanalyzed published Drosophila OSN data (DoOR) and demonstrate substantial shifts in affinities after compensation for quantity and puff number. We conclude that consistent experimental protocols are necessary for correct OSN classification and present some simple rules that make calibration, even retroactively, readily possible.

Quantum key distribution with an unknown and untrusted source

NASA Astrophysics Data System (ADS)

Zhao, Yi; Qi, Bing; Lo, Hoi-Kwong

2008-05-01

The security of a standard bidirectional “plug-and-play” quantum key distribution (QKD) system has been an open question for a long time. This is mainly because its source is equivalently controlled by an eavesdropper, which means the source is unknown and untrusted. Qualitative discussion on this subject has been made previously. In this paper, we solve this question directly by presenting the quantitative security analysis on a general class of QKD protocols whose sources are unknown and untrusted. The securities of standard Bennett-Brassard 1984 protocol, weak+vacuum decoy state protocol, and one-decoy state protocol, with unknown and untrusted sources are rigorously proved. We derive rigorous lower bounds to the secure key generation rates of the above three protocols. Our numerical simulation results show that QKD with an untrusted source gives a key generation rate that is close to that with a trusted source.

3D T2-weighted imaging to shorten multiparametric prostate MRI protocols.

PubMed

Polanec, Stephan H; Lazar, Mathias; Wengert, Georg J; Bickel, Hubert; Spick, Claudio; Susani, Martin; Shariat, Shahrokh; Clauser, Paola; Baltzer, Pascal A T

2018-04-01

To determine whether 3D acquisitions provide equivalent image quality, lesion delineation quality and PI-RADS v2 performance compared to 2D acquisitions in T2-weighted imaging of the prostate at 3 T. This IRB-approved, prospective study included 150 consecutive patients (mean age 63.7 years, 35-84 years; mean PSA 7.2 ng/ml, 0.4-31.1 ng/ml). Two uroradiologists (R1, R2) independently rated image quality and lesion delineation quality using a five-point ordinal scale and assigned a PI-RADS score for 2D and 3D T2-weighted image data sets. Data were compared using visual grading characteristics (VGC) and receiver operating characteristics (ROC)/area under the curve (AUC) analysis. Image quality was similarly good to excellent for 2D T2w (mean score R1, 4.3 ± 0.81; R2, 4.7 ± 0.83) and 3D T2w (mean score R1, 4.3 ± 0.82; R2, 4.7 ± 0.69), p = 0.269. Lesion delineation was rated good to excellent for 2D (mean score R1, 4.16 ± 0.81; R2, 4.19 ± 0.92) and 3D T2w (R1, 4.19 ± 0.94; R2, 4.27 ± 0.94) without significant differences (p = 0.785). ROC analysis showed an equivalent performance for 2D (AUC 0.580-0.623) and 3D (AUC 0.576-0.629) T2w (p > 0.05, respectively). Three-dimensional acquisitions demonstrated equivalent image and lesion delineation quality, and PI-RADS v2 performance, compared to 2D in T2-weighted imaging of the prostate. Three-dimensional T2-weighted imaging could be used to considerably shorten prostate MRI protocols in clinical practice. • 3D shows equivalent image quality and lesion delineation compared to 2D T2w. • 3D T2w and 2D T2w image acquisition demonstrated comparable diagnostic performance. • Using a single 3D T2w acquisition may shorten the protocol by 40%. • Combined with short DCE, multiparametric protocols of 10 min are feasible.

The transfer of Crel contextual control (same, opposite, less than, more than) through equivalence relations.

PubMed

Perez, William F; Kovac, Roberta; Nico, Yara C; Caro, Daniel M; Fidalgo, Adriana P; Linares, Ila; de Almeida, João Henrique; de Rose, Júlio C

2017-11-01

According to Relational Frame Theory (RFT) C rel denotes a contextual stimulus that controls a particular type of relational response (sameness, opposition, comparative, temporal, hierarchical etc.) in a given situation. Previous studies suggest that contextual functions may be indirectly acquired via transfer of function. The present study investigated the transfer of C rel contextual control through equivalence relations. Experiment 1 evaluated the transfer of C rel contextual functions for relational responses based on sameness and opposition. Experiment 2 extended these findings by evaluating transfer of function using comparative C rel stimuli. Both experiments followed a similar sequence of phases. First, abstract forms were established as C rel stimuli via multiple exemplar training (Phase 1). The contextual cues were then applied to establish arbitrary relations among nonsense words and to test derived relations (Phase 2). After that, equivalence relations involving the original C rel stimuli and other abstract forms were trained and tested (Phase 3). Transfer of function was evaluated by replacing the directly established C rel stimuli with their equivalent stimuli in the former experimental tasks (Phases 1 and 2). Results from both experiments suggest that C rel contextual control may be extended via equivalence relations, allowing other arbitrarily related stimuli to indirectly acquire C rel functions and regulate behavior by evoking appropriate relational responses in the presence of both previously known and novel stimuli. © 2017 Society for the Experimental Analysis of Behavior.

Establishing Substantial Equivalence: Transcriptomics

NASA Astrophysics Data System (ADS)

Baudo, María Marcela; Powers, Stephen J.; Mitchell, Rowan A. C.; Shewry, Peter R.

Regulatory authorities in Western Europe require transgenic crops to be substantially equivalent to conventionally bred forms if they are to be approved for commercial production. One way to establish substantial equivalence is to compare the transcript profiles of developing grain and other tissues of transgenic and conventionally bred lines, in order to identify any unintended effects of the transformation process. We present detailed protocols for transcriptomic comparisons of developing wheat grain and leaf material, and illustrate their use by reference to our own studies of lines transformed to express additional gluten protein genes controlled by their own endosperm-specific promoters. The results show that the transgenes present in these lines (which included those encoding marker genes) did not have any significant unpredicted effects on the expression of endogenous genes and that the transgenic plants were therefore substantially equivalent to the corresponding parental lines.

Water-equivalence of gel dosimeters for radiology medical imaging.

PubMed

Valente, M; Vedelago, J; Chacón, D; Mattea, F; Velásquez, J; Pérez, P

2018-03-08

International dosimetry protocols are based on determinations of absorbed dose to water. Ideally, the phantom material should be water equivalent; that is, it should have the same absorption and scatter properties as water. This study presents theoretical, experimental and Monte Carlo modeling of water-equivalence of Fricke and polymer (NIPAM, PAGAT and itaconic acid ITABIS) gel dosimeters. Mass and electronic densities along with effective atomic number were calculated by means of theoretical approaches. Samples were scanned by standard computed tomography. Photon mass attenuation coefficients and electron stopping powers were examined. Theoretical, Monte Carlo and experimental results confirmed good water-equivalence for all gel dosimeters. Overall variations with respect to water in the low energy radiology range (up to 130 kVp) were found to be less than 3% in average. Copyright © 2018 Elsevier Ltd. All rights reserved.

High-Throughput, Survivable Protocols for CDMA Packet-Radio Networks (SRNTN-74)

DTIC Science & Technology

1990-03-01

published in a paper by Jubin and Tornow [2], however the reader must be aware that the current SURAP algorithms deviate slightly from this reference...threading policy outlined by Jubin and Tornow is equivalent to a link- level window size of one, meaning a policy of not transmitting a new packet to a... Tornow . The DARPA packet-radio network protocols. Proceedings of the IEEE, 75(1):21-32, January 1987. [31 N. Gower and J. Jubin. Congestion control using

Enhanced Memory Consolidation Via Automatic Sound Stimulation During Non-REM Sleep.

PubMed

Leminen, Miika M; Virkkala, Jussi; Saure, Emma; Paajanen, Teemu; Zee, Phyllis C; Santostasi, Giovanni; Hublin, Christer; Müller, Kiti; Porkka-Heiskanen, Tarja; Huotilainen, Minna; Paunio, Tiina

2017-03-01

Slow-wave sleep (SWS) slow waves and sleep spindle activity have been shown to be crucial for memory consolidation. Recently, memory consolidation has been causally facilitated in human participants via auditory stimuli phase-locked to SWS slow waves. Here, we aimed to develop a new acoustic stimulus protocol to facilitate learning and to validate it using different memory tasks. Most importantly, the stimulation setup was automated to be applicable for ambulatory home use. Fifteen healthy participants slept 3 nights in the laboratory. Learning was tested with 4 memory tasks (word pairs, serial finger tapping, picture recognition, and face-name association). Additional questionnaires addressed subjective sleep quality and overnight changes in mood. During the stimulus night, auditory stimuli were adjusted and targeted by an unsupervised algorithm to be phase-locked to the negative peak of slow waves in SWS. During the control night no sounds were presented. Results showed that the sound stimulation increased both slow wave (p = .002) and sleep spindle activity (p < .001). When overnight improvement of memory performance was compared between stimulus and control nights, we found a significant effect in word pair task but not in other memory tasks. The stimulation did not affect sleep structure or subjective sleep quality. We showed that the memory effect of the SWS-targeted individually triggered single-sound stimulation is specific to verbal associative memory. Moreover, the ambulatory and automated sound stimulus setup was promising and allows for a broad range of potential follow-up studies in the future. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

[Acceptance and commitment therapy (ACT) and improving chess performance in promising young chess-players].

PubMed

Ruiz, Francisco J; Luciano, Carmen

2009-08-01

Acceptance and Commitment Therapy (ACT) is shown to be effective in relatively distant fields from the so-called psychological disorders. One of these areas is sport performance improvement. The aim of the current study is to expand the application of brief ACT protocols to improve chess-players' performance. In a previous study, a brief protocol was applied to international-level adult chess-players that was effective. The current study aims to apply an equivalent brief ACT protocol, but in this case, applied in a group format to promising young chess-players. In addition, this brief protocol is compared to a non-intervention control condition. Results show that the ACT brief protocol improved the performance in 5 out of 7 participants, and that none of the chess-players in the control condition reached the established change criterion. The differences between the conditions in chess performance were statistically significant. The results are discussed, emphasizing the replicated impact of a brief ACT protocol on the improvement of chess-players' performance.

Electronic Clinical Trial Protocol Distribution via the World-Wide Web

PubMed Central

Afrin, Lawrence B.; Kuppuswamy, Valarmathi; Slater, Barbara; Stuart, Robert K.

1997-01-01

Clinical trials today typically are inefficient, paper-based operations. Poor community physician awareness of available trials and difficult referral mechanisms also contribute to poor accrual. The Physicians Research Network (PRN) web was developed for more efficient trial protocol distribution and eligibility inquiries. The Medical University of South Carolina's Hollings Cancer Center trials program and two community oncology practices served as a testbed. In 581 man-hours over 18 months, 147 protocols were loaded into PRN. The trials program eliminated all protocol hardcopies except the masters, reduced photocopier use 59%, and saved 1.0 full-time equivalents (FTE), but 1.0 FTE was needed to manage PRN. There were no known security breaches, downtime, or content-related problems. Therefore, PRN is a paperless, user-preferred, reliable, secure method for distributing protocols and reducing distribution errors and delays because only a single copy of each protocol is maintained. Furthermore, PRN is being extended to serve other aspects of trial operations. PMID:8988471

Orienting attention to locations in internal representations.

PubMed

Griffin, Ivan C; Nobre, Anna C

2003-11-15

Three experiments investigated whether it is possible to orient selective spatial attention to internal representations held in working memory in a similar fashion to orienting to perceptual stimuli. In the first experiment, subjects were either cued to orient to a spatial location before a stimulus array was presented (pre-cue), cued to orient to a spatial location in working memory after the array was presented (retro-cue), or given no cueing information (neutral cue). The stimulus array consisted of four differently colored crosses, one in each quadrant. At the end of a trial, a colored cross (probe) was presented centrally, and subjects responded according to whether it had occurred in the array. There were equivalent patterns of behavioral costs and benefits of cueing for both pre-cues and retro-cues. A follow-up experiment used a peripheral probe stimulus requiring a decision about whether its color matched that of the item presented at the same location in the array. Replication of the behavioral costs and benefits of pre-cues and retro-cues in this experiment ruled out changes in response criteria as the only explanation for the effects. The third experiment used event-related potentials (ERPs) to compare the neural processes involved in orienting attention to a spatial location in an external versus an internal spatial representation. In this task, subjects responded according to whether a central probe stimulus occurred at the cued location in the array. There were both similarities and differences between ERPs to spatial cues toward a perception versus an internal spatial representation. Lateralized early posterior and later frontal negativities were observed for both pre- and retro-cues. Retro-cues also showed additional neural processes to be involved in orienting to an internal representation, including early effects over frontal electrodes.

Tracking speech comprehension in space and time.

PubMed

Pulvermüller, Friedemann; Shtyrov, Yury; Ilmoniemi, Risto J; Marslen-Wilson, William D

2006-07-01

A fundamental challenge for the cognitive neuroscience of language is to capture the spatio-temporal patterns of brain activity that underlie critical functional components of the language comprehension process. We combine here psycholinguistic analysis, whole-head magnetoencephalography (MEG), the Mismatch Negativity (MMN) paradigm, and state-of-the-art source localization techniques (Equivalent Current Dipole and L1 Minimum-Norm Current Estimates) to locate the process of spoken word recognition at a specific moment in space and time. The magnetic MMN to words presented as rare "deviant stimuli" in an oddball paradigm among repetitive "standard" speech stimuli, peaked 100-150 ms after the information in the acoustic input, was sufficient for word recognition. The latency with which words were recognized corresponded to that of an MMN source in the left superior temporal cortex. There was a significant correlation (r = 0.7) of latency measures of word recognition in individual study participants with the latency of the activity peak of the superior temporal source. These results demonstrate a correspondence between the behaviorally determined recognition point for spoken words and the cortical activation in left posterior superior temporal areas. Both the MMN calculated in the classic manner, obtained by subtracting standard from deviant stimulus response recorded in the same experiment, and the identity MMN (iMMN), defined as the difference between the neuromagnetic responses to the same stimulus presented as standard and deviant stimulus, showed the same significant correlation with word recognition processes.

Signals, resistance to change, and conditioned reinforcement in a multiple schedule.

PubMed

Bell, Matthew C; Gomez, Belen E; Kessler, Kira

2008-06-01

The effect of signals on resistance to change was evaluated using pigeons responding on a three-component multiple schedule. Each component contained a variable-interval initial link followed by a fixed-time terminal link. One component was an unsignaled-delay schedule, and two were equivalent signaled-delay schedules. After baseline training, resistance to change was assessed through (a) extinction and (b) adding free food to the intercomponent interval. During these tests, the signal stimulus from one of the signaled-delay components (SIG-T) was replaced with the initial-link stimulus from that component, converting it to an unsignaled-delay schedule. That signal stimulus was added to the delay period of the unsignaled-delay component (UNS), converting it to a signaled-delay schedule. The remaining signaled component remained unchanged (SIG-C). Resistance-to-change tests showed removing the signal had a minimal effect on resistance to change in the SIG-T component compared to the unchanged SIG-C component except for one block during free-food testing. Adding the signal to the UNS component significantly increased response rates suggesting that component had low response strength. Interestingly, the direction of the effect was in the opposite direction from what is typically observed. Results are consistent with the conclusion that the signal functioned as a conditioned reinforcer and inconsistent with a generalization-decrement explanation.

Fasting: a major limitation for resistance exercise training effects in rodents

PubMed Central

das Neves, W.; de Oliveira, L.F.; da Silva, R.P.; Alves, C.R.R.; Lancha, A.H.

2017-01-01

Protocols that mimic resistance exercise training (RET) in rodents present several limitations, one of them being the electrical stimulus, which is beyond the physiological context observed in humans. Recently, our group developed a conditioning system device that does not use electric shock to stimulate rats, but includes fasting periods before each RET session. The current study was designed to test whether cumulative fasting periods have some influence on skeletal muscle mass and function. Three sets of male Wistar rats were used in the current study. The first set of rats was submitted to a RET protocol without food restriction. However, rats were not able to perform exercise properly. The second and third sets were then randomly assigned into three experimental groups: 1) untrained control rats, 2) untrained rats submitted to fasting periods, and 3) rats submitted to RET including fasting periods before each RET session. While the second set of rats performed a short RET protocol (i.e., an adaptation protocol for 3 weeks), the third set of rats performed a longer RET protocol including overload (i.e., 8 weeks). After the short-term protocol, cumulative fasting periods promoted loss of weight (P<0.001). After the longer RET protocol, no difference was observed for body mass, extensor digitorum longus (EDL) morphology or skeletal muscle function (P>0.05 for all). Despite no effects on EDL mass, soleus muscle displayed significant atrophy in the fasting experimental groups (P<0.01). Altogether, these data indicate that fasting is a major limitation for RET in rats. PMID:29185588

IL-6, Antioxidant Capacity and Muscle Damage Markers Following High-Intensity Interval Training Protocols

PubMed Central

2017-01-01

Abstract The aim of this study was to investigate changes of interleukin-6 (IL-6), total antioxidant capacity (TAC) and muscle damage markers (creatine kinase (CK), myoglobin and lactate dehydrogenase (LDH)) in response to three different high-intensity interval training (HIIT) protocols of identical external work. Twelve moderately-trained males participated in the three HIIT trials which consisted of a warm-up, followed by 12 min of 15 s, 30 s or 60 s HIIT sequences with the work/rest ratio 1. The biochemical markers of inflammation, oxidative stress and muscle damage were analysed POST, 3 h and 24 h after the exercise. All HIIT protocols caused an immediate increase in IL-6, TAC, CK, myoglobin and LDH. The most pronounced between-trials differences were found for the POST-exercise changes in IL-6 (Effect size ± 90% confidence interval: 1.51 ± 0.63, 0.84 ± 0.34 and 1.80 ± 0.60 for the 15s/15s, 30s/30s and 60s/60s protocol, respectively) and myoglobin (1.11 ± 0.29, 0.45 ± 0.48 and 1.09 ± 0.22 for the 15s/15s, 30s/30s and 60s/60s protocol, respectively). There were no substantial between-trial differences in other biochemical variables. In conclusion, the 15s/15s and 60s/60s protocols might be preferred to the 30s/30s protocols in order to maximize the training stimulus. PMID:28469752

Fasting: a major limitation for resistance exercise training effects in rodents.

PubMed

das Neves, W; de Oliveira, L F; da Silva, R P; Alves, C R R; Lancha, A H

2017-11-17

Protocols that mimic resistance exercise training (RET) in rodents present several limitations, one of them being the electrical stimulus, which is beyond the physiological context observed in humans. Recently, our group developed a conditioning system device that does not use electric shock to stimulate rats, but includes fasting periods before each RET session. The current study was designed to test whether cumulative fasting periods have some influence on skeletal muscle mass and function. Three sets of male Wistar rats were used in the current study. The first set of rats was submitted to a RET protocol without food restriction. However, rats were not able to perform exercise properly. The second and third sets were then randomly assigned into three experimental groups: 1) untrained control rats, 2) untrained rats submitted to fasting periods, and 3) rats submitted to RET including fasting periods before each RET session. While the second set of rats performed a short RET protocol (i.e., an adaptation protocol for 3 weeks), the third set of rats performed a longer RET protocol including overload (i.e., 8 weeks). After the short-term protocol, cumulative fasting periods promoted loss of weight (P<0.001). After the longer RET protocol, no difference was observed for body mass, extensor digitorum longus (EDL) morphology or skeletal muscle function (P>0.05 for all). Despite no effects on EDL mass, soleus muscle displayed significant atrophy in the fasting experimental groups (P<0.01). Altogether, these data indicate that fasting is a major limitation for RET in rats.

Intermittent and continuous high-intensity exercise training induce similar acute but different chronic muscle adaptations.

PubMed

Cochran, Andrew J R; Percival, Michael E; Tricarico, Steven; Little, Jonathan P; Cermak, Naomi; Gillen, Jenna B; Tarnopolsky, Mark A; Gibala, Martin J

2014-05-01

High-intensity interval training (HIIT) performed in an 'all-out' manner (e.g. repeated Wingate tests) is a time-efficient strategy to induce skeletal muscle remodelling towards a more oxidative phenotype. A fundamental question that remains unclear, however, is whether the intermittent or 'pulsed' nature of the stimulus is critical to the adaptive response. In study 1, we examined whether the activation of signalling cascades linked to mitochondrial biogenesis was dependent on the manner in which an acute high-intensity exercise stimulus was applied. Subjects performed either four 30 s Wingate tests interspersed with 4 min of rest (INT) or a bout of continuous exercise (CONT) that was matched for total work (67 ± 7 kJ) and which required ∼4 min to complete as fast as possible. Both protocols elicited similar increases in markers of adenosine monophosphate-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase activation, as well as Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) mRNA expression (main effects for time, P ≤ 0.05). In study 2, we determined whether 6 weeks of the CONT protocol (3 days per week) would increase skeletal muscle mitochondrial content to a similar extent to what we have previously reported after 6 weeks of INT. Despite similar acute signalling responses to the CONT and INT protocols, training with CONT did not increase the maximal activity or protein content of a range of mitochondrial markers. However, peak oxygen uptake was higher after CONT training (from 45.7 ± 5.4 to 48.3 ± 6.5 ml kg(-1) min(-1); P < 0.05) and 250 kJ time trial performance was improved (from 26:32 ± 4:48 to 23:55 ± 4:16 min:s; P < 0.001) in our recreationally active participants. We conclude that the intermittent nature of the stimulus is important for maximizing skeletal muscle adaptations to low-volume, all-out HIIT. Despite the lack of skeletal muscle mitochondrial adaptations, our data show that a training programme based on a brief bout of high-intensity exercise, which lasted <10 min per session including warm-up, and performed three times per week for 6 weeks, improved peak oxygen uptake in young healthy subjects. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

Apomorphine conditioning and sensitization: the paired/unpaired treatment order as a new major determinant of drug conditioned and sensitization effects.

PubMed

de Matos, Liana Wermelinger; Carey, Robert J; Carrera, Marinete Pinheiro

2010-09-01

Repeated treatments with psychostimulant drugs generate behavioral sensitization. In the present study we employed a paired/unpaired protocol to assess the effects of repeated apomorphine (2.0 mg/kg) treatments upon locomotion behavior. In the first experiment we assessed the effects of conditioning upon apomorphine sensitization. Neither the extinction of the conditioned response nor a counter-conditioning procedure in which we paired an inhibitory treatment (apomorphine 0.05 mg/kg) with the previously established conditioned stimulus modified the sensitization response. In the second experiment, we administered the paired/unpaired protocol in two phases. In the second phase, we reversed the paired/unpaired protocol. Following the first phase, the paired group alone exhibited conditioned locomotion in the vehicle test and a sensitization response. In the second phase, the initial unpaired group which received 5 paired apomorphine trials during the reversal phase did not develop a conditioned response but developed a potentiated sensitization response. This disassociation of the conditioned response from the sensitization response is attributed to an apomorphine anti-habituation effect that can generate a false positive Pavlovian conditioned response effect. The potentiated sensitization response induced by the treatment reversal protocol points to an important role for the sequential experience of the paired/unpaired protocol in behavioral sensitization. 2010 Elsevier Inc. All rights reserved.

Loaded hip thrust-based PAP protocol effects on acceleration and sprint performance of handball players.

PubMed

Dello Iacono, Antonio; Padulo, Johnny; Seitz, Laurent D

2018-06-01

This study aimed to investigate the acute effects of two barbell hip thrust-based (BHT) post-activation potentiation (PAP) protocols on subsequent sprint performance. Using a crossover design, eighteen handball athletes performed maximal 15-m sprints before and 15s, 4min and 8min after two experimental protocols consisting of BHT loaded with either 50% or 85% 1RM (50PAP and 85PAP, respectively), in order to profile the transient PAP effects. The resulting sprint performances were significantly impaired at 15s only after the 85PAP protocol, which induced likely and very likely greater decreases compared to the 50PAP. At 4min and 8min, significant improvements and very likely beneficial effects were observed in the 10m and 15m performances following both protocols. Significant differences were found when comparing the two PAPs over time; the results suggested very likely greater performance improvements in 10m following the 85PAP after 4min and 8min, and possible greater performance improvements in 15m after 4min. Positive correlations between BHT 1RMs values and the greatest individual PAP responses on sprint performance were found. This investigation showed that both moderate and intensive BHT exercises can induce a PAP response, but the effects may differ according to the recovery following the potentiating stimulus and the individual`s strength level.

The touchscreen operant platform for assessing executive function in rats and mice

PubMed Central

Mar, Adam C.; Horner, Alexa E.; Nilsson, Simon R.O.; Alsiö, Johan; Kent, Brianne A.; Kim, Chi Hun; Holmes, Andrew; Saksida, Lisa M.; Bussey, Timothy J.

2014-01-01

Summary This protocol details a subset of assays developed within the touchscreen platform to measure aspects of executive function in rodents. Three main procedures are included: Extinction, measuring the rate and extent of curtailing a response that was previously, but is no longer, associated with reward; Reversal Learning, measuring the rate and extent of switching a response toward a visual stimulus that was previously not, but has become, associated with reward (and away from a visual stimulus that was previously, but is no longer, rewarded); and the 5-Choice Serial Reaction Time (5-CSRT) task, gauging the ability to selectively detect and appropriately respond to briefly presented, spatially unpredictable visual stimuli. These methods were designed to assess both complimentary and overlapping constructs including selective and divided visual attention, inhibitory control, flexibility, impulsivity and compulsivity. The procedures comprise part of a wider touchscreen test battery assessing cognition in rodents with high potential for translation to human studies. PMID:24051960

Implementation and Integration of a Finite Element Model into the Bone Remodeling Model to Characterize Skeletal Loading

NASA Technical Reports Server (NTRS)

Werner, C. R.; Lewandowski, B.; Boppana, A.; Pennline, J. A.

2017-01-01

NASA's Digital Astronaut Project is developing a bone physiology model to predict changes in bone mineral density over the course of a space mission. The model intends to predict bone loss due to exposure in microgravity as well as predicting bone maintenance due to mechanical stimulus generated by exercise countermeasures. These predictions will be used to inform exercise device efficacy and to help design exercise protocols that will maintain bone mineral density during long exposures to microgravity during spaceflight. The mechanical stimulus and the stresses that are exhibited on the bone are important factors for bone remodeling. These stresses are dependent on the types of exercise that are performed and vary throughout the bone due to the geometry. A primary area of focus for bone health is the proximal femur. This location is critical in transmitting loads between the upper and lower body and have been known to be a critical failure point in older individuals with conditions like osteoporosis.

Assessment and risk classification protocol for patients in emergency units1

PubMed Central

Silva, Michele de Freitas Neves; Oliveira, Gabriela Novelli; Pergola-Marconato, Aline Maino; Marconato, Rafael Silva; Bargas, Eliete Boaventura; Araujo, Izilda Esmenia Muglia

2014-01-01

Objective to develop, validate the contents and verify the reliability of a risk classification protocol for an Emergency Unit. Method the content validation was developed in a University Hospital in a country town located in the state of Sao Paulo and was carried out in two stages: the first with the individual assessment of specialists and the second with the meeting between the researchers and the specialists. The use of the protocol followed a specific guide. Concerning reliability, the concordance or equivalent method among observers was used. Results the protocol developed showed to have content validity and, after the suggested changes were made, there were excellent results concerning reliability. Conclusion the assistance flow chart was shown to be easy to use, and facilitate the search for the complaint in each assistance priority. PMID:26107828

Measurement of cardiopulmonary performance during acute exposure to a 2440-m equivalent atmosphere

NASA Technical Reports Server (NTRS)

Levitan, B. M.; Bungo, M. W.

1982-01-01

Each of 20 subjects (ranging in age from 18 to 38 years, 15 being male, five female) was given two Bruce Protocol symptom-limited maximum treadmill stress tests, breathing sea-level compressed air (20.9% O2) for one test and a 2440-m equivalent (15.5% O2) for the other. A significant difference was found to exist between measured VO2 max (p less than 0.0002) and exercise time (p less than 0.0004) for the two conditions. No significant differences were observed in heart rate or the recovery time to a respiratory quotient of less than 1. Hemoglobin saturation, as measured by an ear oximeter, averaged 95% for sea-level and 91% for the 2440-m equivalent gases. These results support a 2440-m equivalent contingency atmosphere in the Space Shuttle prior to donning a low-pressure suit for the purpose reducing nitrogen washout times.

A general dual-bolus approach for quantitative DCE-MRI.

PubMed

Kershaw, Lucy E; Cheng, Hai-Ling Margaret

2011-02-01

To present a dual-bolus technique for quantitative dynamic contrast-enhanced MRI (DCE-MRI) and show that it can give an arterial input function (AIF) measurement equivalent to that from a single-bolus protocol. Five rabbits were imaged using a dual-bolus technique applicable for high-resolution DCE-MRI, incorporating a time resolved imaging of contrast kinetics (TRICKS) sequence for rapid temporal sampling. AIFs were measured from both the low-dose prebolus and the high-dose main bolus in the abdominal aorta. In one animal, TRICKS and fast spoiled gradient echo (FSPGR) acquisitions were compared. The scaled prebolus AIF was shown to match the main bolus AIF, with 95% confidence intervals overlapping for fits of gamma-variate functions to the first pass and linear fits to the washout phase, with the exception of one case. The AIFs measured using TRICKS and FSPGR were shown to be equivalent in one animal. The proposed technique can capture even the rapid circulation kinetics in the rabbit aorta, and the scaled prebolus AIF is equivalent to the AIF from a high-dose injection. This allows separate measurements of the AIF and tissue uptake curves, meaning that each curve can then be acquired using a protocol tailored to its specific requirements. Copyright © 2011 Elsevier Inc. All rights reserved.

Sensitivity and integration in a visual pathway for circadian entrainment in the hamster (Mesocricetus auratus).

PubMed Central

Nelson, D E; Takahashi, J S

1991-01-01

1. Light-induced phase shifts of the circadian rhythm of wheel-running activity were used to measure the photic sensitivity of a circadian pacemaker and the visual pathway that conveys light information to it in the golden hamster (Mesocricetus auratus). The sensitivity to stimulus irradiance and duration was assessed by measuring the magnitude of phase-shift responses to photic stimuli of different irradiance and duration. The visual sensitivity was also measured at three different phases of the circadian rhythm. 2. The stimulus-response curves measured at different circadian phases suggest that the maximum phase-shift is the only aspect of visual responsivity to change as a function of the circadian day. The half-saturation constants (sigma) for the stimulus-response curves are not significantly different over the three circadian phases tested. The photic sensitivity to irradiance (1/sigma) appears to remain constant over the circadian day. 3. The hamster circadian pacemaker and the photoreceptive system that subserves it are more sensitive to the irradiance of longer-duration stimuli than to irradiance of briefer stimuli. The system is maximally sensitive to the irradiance of stimuli of 300 s and longer in duration. A quantitative model is presented to explain the changes that occur in the stimulus-response curves as a function of photic stimulus duration. 4. The threshold for photic stimulation of the hamster circadian pacemaker is also quite high. The threshold irradiance (the minimum irradiance necessary to induce statistically significant responses) is approximately 10(11) photons cm-2 s-1 for optimal stimulus durations. This threshold is equivalent to a luminance at the cornea of 0.1 cd m-2. 5. We also measured the sensitivity of this visual pathway to the total number of photons in a stimulus. This system is maximally sensitive to photons in stimuli between 30 and 3600 s in duration. The maximum quantum efficiency of photic integration occurs in 300 s stimuli. 6. These results suggest that the visual pathways that convey light information to the mammalian circadian pacemaker possess several unique characteristics. These pathways are relatively insensitive to light irradiance and also integrate light inputs over relatively long durations. This visual system, therefore, possesses an optimal sensitivity of 'tuning' to total photons delivered in stimuli of several minutes in duration. Together these characteristics may make this visual system unresponsive to environmental 'noise' that would interfere with the entrainment of circadian rhythms to light-dark cycles. PMID:1895235

Visualization of cortical, subcortical, and deep brain neural circuit dynamics during naturalistic mammalian behavior with head-mounted microscopes and chronically implanted lenses

PubMed Central

Resendez, Shanna L.; Jennings, Josh H.; Ung, Randall L.; Namboodiri, Vijay Mohan K.; Zhou, Zhe Charles; Otis, James M.; Nomura, Hiroshi; McHenry, Jenna A.; Kosyk, Oksana; Stuber, Garret D.

2016-01-01

Genetically encoded calcium indicators for visualizing dynamic cellular activity have greatly expanded our understanding of the brain. However, due to light scattering properties of the brain as well as the size and rigidity of traditional imaging technology, in vivo calcium imaging has been limited to superficial brain structures during head fixed behavioral tasks. This limitation can now be circumvented by utilizing miniature, integrated microscopes in conjunction with an implantable microendoscopic lens to guide light into and out of the brain, thus permitting optical access to deep brain (or superficial) neural ensembles during naturalistic behaviors. Here, we describe procedural steps to conduct such imaging studies using mice. However, we anticipate the protocol can be easily adapted for use in other small vertebrates. Successful completion of this protocol will permit cellular imaging of neuronal activity and the generation of data sets with sufficient statistical power to correlate neural activity with stimulus presentation, physiological state, and other aspects of complex behavioral tasks. This protocol takes 6–11 weeks to complete. PMID:26914316

Fluid management with a simplified conservative protocol for the acute respiratory distress syndrome*.

PubMed

Grissom, Colin K; Hirshberg, Eliotte L; Dickerson, Justin B; Brown, Samuel M; Lanspa, Michael J; Liu, Kathleen D; Schoenfeld, David; Tidswell, Mark; Hite, R Duncan; Rock, Peter; Miller, Russell R; Morris, Alan H

2015-02-01

In the Fluid and Catheter Treatment Trial (FACTT) of the National Institutes of Health Acute Respiratory Distress Syndrome Network, a conservative fluid protocol (FACTT Conservative) resulted in a lower cumulative fluid balance and better outcomes than a liberal fluid protocol (FACTT Liberal). Subsequent Acute Respiratory Distress Syndrome Network studies used a simplified conservative fluid protocol (FACTT Lite). The objective of this study was to compare the performance of FACTT Lite, FACTT Conservative, and FACTT Liberal protocols. Retrospective comparison of FACTT Lite, FACTT Conservative, and FACTT Liberal. Primary outcome was cumulative fluid balance over 7 days. Secondary outcomes were 60-day adjusted mortality and ventilator-free days through day 28. Safety outcomes were prevalence of acute kidney injury and new shock. ICUs of Acute Respiratory Distress Syndrome Network participating hospitals. Five hundred three subjects managed with FACTT Conservative, 497 subjects managed with FACTT Liberal, and 1,124 subjects managed with FACTT Lite. Fluid management by protocol. Cumulative fluid balance was 1,918 ± 323 mL in FACTT Lite, -136 ± 491 mL in FACTT Conservative, and 6,992 ± 502 mL in FACTT Liberal (p < 0.001). Mortality was not different between groups (24% in FACTT Lite, 25% in FACTT Conservative and Liberal, p = 0.84). Ventilator-free days in FACTT Lite (14.9 ± 0.3) were equivalent to FACTT Conservative (14.6 ± 0.5) (p = 0.61) and greater than in FACTT Liberal (12.1 ± 0.5, p < 0.001 vs Lite). Acute kidney injury prevalence was 58% in FACTT Lite and 57% in FACTT Conservative (p = 0.72). Prevalence of new shock in FACTT Lite (9%) was lower than in FACTT Conservative (13%) (p = 0.007 vs Lite) and similar to FACTT Liberal (11%) (p = 0.18 vs Lite). FACTT Lite had a greater cumulative fluid balance than FACTT Conservative but had equivalent clinical and safety outcomes. FACTT Lite is an alternative to FACTT Conservative for fluid management in Acute Respiratory Distress Syndrome.

Change in clinical indices following laser or scalpel treatment for periodontitis: A split-mouth, randomized, multi-center trial

NASA Astrophysics Data System (ADS)

Harris, David M.; Nicholson, Dawn M.; McCarthy, Delwin; Yukna, Raymond A.; Reynolds, Mark A.; Greenwell, Henry; Finley, James; McCawley, Thomas K.; Xenoudi, Pinelopi; Gregg, Robert H.

2014-02-01

Data are presented from a multi-center, prospective, longitudinal, clinical trial comparing four different treatments for periodontitis, (1) the LANAPTM protocol utilizing a FR pulsed-Nd:YAG laser; (2) flap surgery using the Modified Widman technique (MWF); (3) traditional scaling and root planing (SRP); and (4) coronal debridement (CD). Each treatment was randomized to a different quadrant. Fifty-one (54) subjects were recruited at five centers that included both private practice and university-based investigators. At 6-months and 12 months post-treatment the LANAPTM protocol and MWF yielded equivalent results based on changes in probing depths. The major difference observed between the two procedures was that patients reported significantly greater comfort following the LANAP™ procedure than following the MWF (P<0.001). There was greater reduction in bleeding in the LANAPTM quadrant than in the other three at both 6 and 12 months. Improvements following SRP were better than expected at 6 months and continued to improve, providing outcomes that were equivalent to both LANAPTM and MWF at 12 months. The improvement in the SRP quadrants suggests the hypothesis that an aspect of the LANAPTM protocol generated a significant, positive and unanticipated systemic (or trans-oral) effect on sub-gingival wound healing.

Retinal Atherosclerosis, Ophthalmologically Reported and Documented with OSA in 1987, is now Totally Reversed, and Recorded, Photographically. The Supposition then was that Equivalent Cortical Damage could Respond to the same Healing Protocol.

NASA Astrophysics Data System (ADS)

Niemi, Paul N.; O., D.; Mc Leod, David M.; Mc Leod, Roger D.

2007-10-01

Documented retinal atherosclerosis, ``silver streaking'' of retinal capillaries, was reported and documented with OSA, in October 1987. That retinal damage, despite claims it usually progresses and is nonreversible, is now completely cleared. The original OSA presentation proposed that equivalent cortical damage was probably present throughout the brain at that time, as attested by failing short-term memory performance and transient ischemic attacks, TIAs, brief vision strokes. The supposition then was that ophthalmologic access to the retina, by some accounts the progenitor of all brain evolution, could provide a means of monitoring the actual circulatory state of inaccessible parts of the brain. To the extent that retinal health was naturopathically restored, and memory performance seems also to have significantly kept pace, is it a tenable premise that such protocols have rather general importance? Can applied optics help establish more appropriate diagnoses, and evaluate treatments for dementia and Alzheimer's disease?

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

PubMed Central

Gau, Michael R.; Zdilla, Michael J.

2016-01-01

Organolithium reagents are powerful tools in the synthetic chemist's toolbox. However, the extreme pyrophoric nature of the most reactive reagents warrants proper technique, thorough training, and proper personal protective equipment. To aid in the training of researchers using organolithium reagents, a thorough, step-by-step protocol for the safe and effective use of tert-butyllithium on an inert gas line or within a glovebox is described. As a model reaction, preparation of lithium tert-butyl amide by the reaction of tert-butyl amine with one equivalent of tert-butyl lithium is presented. PMID:27911386

Influence of ballistic bench press on upper body power output in professional rugby players.

PubMed

West, Daniel J; Cunningham, Daniel J; Crewther, Blair T; Cook, Christian J; Kilduff, Liam P

2013-08-01

The use of heavy resistance exercise provides an effective preload stimulus for inducing postactivation potentiation (PAP) and increasing peak power output (PPO). However, this approach has limited application in many sporting situations (e.g., incorporation in a precompetition warm-up); and therefore, more practical strategies for inducing PAP need to be investigated. The aim of the present study was to compare the PPO changes after performing a preload stimulus of either a ballistic exercise or a traditional heavy resistance exercise. Twenty professional rugby union players completed 3 testing sessions, each separated by 48 hours. On the first occasion, subjects underwent a 3 repetition maximum (3RM)-bench press testing session. On the next 2 occasions, subjects performed a ballistic bench throw at baseline (30% of 1RM), followed by a preload stimulus of either heavy resistance training (HRT) (heavy bench press: 3 sets of 3 repetitions at 87% 1RM) or BBP (3 sets of 3 repetitions at 30% on 1RM) followed by ballistic bench throw after 8 minutes recovery. The trials were randomized and counterbalanced. Both preload stimuli protocols increased PPO compared with baseline (BBP baseline 892 ± 108 vs. 8 minutes 924 ± 119 W, p < 0.001; HRT baseline 893 ± 104 vs. 8 minutes 931 ± 116 W; p < 0.001). There were no conditional differences between PPO at 8 minutes (p = 0.141); moreover, the change in PPO from baseline was also similar between conditions (BBP Δ + 33 ± 18; HRT Δ + 38 ± 21 W; p = 0.112). In conclusion, a ballistic exercise provided an effective method of inducing PAP and increasing upper-body PPO; moreover, this elicited similar increases in PPO as a traditional heavy resistance exercise preloading stimulus.

New indices from microneurography to investigate the arterial baroreflex.

PubMed

Laurin, Alexandre; Lloyd, Matthew G; Hachiya, Tesshin; Saito, Mitsuru; Claydon, Victoria E; Blaber, Andrew

2017-06-01

Baroreflex-mediated changes in heart rate and vascular resistance in response to variations in blood pressure are critical to maintain homeostasis. We aimed to develop time domain analysis methods to complement existing cross-spectral techniques in the investigation of the vascular resistance baroreflex response to orthostatic stress. A secondary goal was to apply these methods to distinguish between levels of orthostatic tolerance using baseline data. Eleven healthy, normotensive males participated in a graded lower body negative pressure protocol. Within individual neurogenic baroreflex cycles, the amount of muscle sympathetic nerve activity (MSNA), the diastolic pressure stimulus and response amplitudes, diastolic pressure to MSNA burst stimulus and response times, as well as the stimulus and response slopes between diastolic pressure and MSNA were computed. Coherence, gain, and frequency of highest coherence between systolic/diastolic arterial pressure (SAP/DAP) and RR-interval time series were also computed. The number of MSNA bursts per low-frequency cycle increased from 2.55 ± 0.68 at baseline to 5.44 ± 1.56 at -40 mmHg of LBNP Stimulus time decreased (3.21 ± 1.48-1.46 ± 0.43 sec), as did response time (3.47 ± 0.86-2.37 ± 0.27 sec). At baseline, DAP-RR coherence, DAP-RR gain, and the time delay between decreases in DAP and MSNA bursts were higher in participants who experienced symptoms of presyncope. Results clarified the role of different branches of the baroreflex loop, and suggested functional adaptation of neuronal pathways to orthostatic stress. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Evaluation of viremia, proviral load and cytokine profile in naturally feline immunodeficiency virus infected cats treated with two different protocols of recombinant feline interferon omega.

PubMed

Leal, Rodolfo O; Gil, Solange; Duarte, Ana; McGahie, David; Sepúlveda, Nuno; Niza, Maria M R E; Tavares, Luís

2015-04-01

This study assesses viremia, provirus and blood cytokine profile in naturally FIV-infected cats treated with two distinct protocols of interferon omega (rFeIFN-ω). Samples from FIV-cats previously submitted to two single-arm studies were used: 7/18 received the licensed/subcutaneous protocol (SC) while 11/18 were treated orally (PO). Viremia, provirus and blood mRNA expression of interleukin (IL)-1, IL-4, IL-6, IL-10, IL-12p40, Interferon-γ and Tumor Necrosis Factor-α were monitored by Real-Time qPCR. Concurrent plasma levels of IL-6, IL-12p40 and IL-4 were assessed by ELISA. IL-6 plasma levels decreased in the SC group (p = 0.031). IL-6 mRNA expression (p = 0.037) decreased in the PO group, albeit not sufficiently to change concurrent plasma levels. Neither viremia nor other measured cytokines changed with therapy. Proviral load increased in the SC group (p = 0.031), which can be justified by a clinically irrelevant increase of lymphocyte count. Independently of the protocol, rFeIFN-ω seems to act on innate immunity by reducing pro-inflammatory stimulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantum key distribution with an unknown and untrusted source

NASA Astrophysics Data System (ADS)

Zhao, Yi; Qi, Bing; Lo, Hoi-Kwong

2009-03-01

The security of a standard bi-directional ``plug & play'' quantum key distribution (QKD) system has been an open question for a long time. This is mainly because its source is equivalently controlled by an eavesdropper, which means the source is unknown and untrusted. Qualitative discussion on this subject has been made previously. In this paper, we present the first quantitative security analysis on a general class of QKD protocols whose sources are unknown and untrusted. The securities of standard BB84 protocol, weak+vacuum decoy state protocol, and one-decoy decoy state protocol, with unknown and untrusted sources are rigorously proved. We derive rigorous lower bounds to the secure key generation rates of the above three protocols. Our numerical simulation results show that QKD with an untrusted source gives a key generation rate that is close to that with a trusted source. Our work is published in [1]. [4pt] [1] Y. Zhao, B. Qi, and H.-K. Lo, Phys. Rev. A, 77:052327 (2008).

DETECTION AND IDENTIFICATION OF SPEECH SOUNDS USING CORTICAL ACTIVITY PATTERNS

PubMed Central

Centanni, T.M.; Sloan, A.M.; Reed, A.C.; Engineer, C.T.; Rennaker, R.; Kilgard, M.P.

2014-01-01

We have developed a classifier capable of locating and identifying speech sounds using activity from rat auditory cortex with an accuracy equivalent to behavioral performance without the need to specify the onset time of the speech sounds. This classifier can identify speech sounds from a large speech set within 40 ms of stimulus presentation. To compare the temporal limits of the classifier to behavior, we developed a novel task that requires rats to identify individual consonant sounds from a stream of distracter consonants. The classifier successfully predicted the ability of rats to accurately identify speech sounds for syllable presentation rates up to 10 syllables per second (up to 17.9 ± 1.5 bits/sec), which is comparable to human performance. Our results demonstrate that the spatiotemporal patterns generated in primary auditory cortex can be used to quickly and accurately identify consonant sounds from a continuous speech stream without prior knowledge of the stimulus onset times. Improved understanding of the neural mechanisms that support robust speech processing in difficult listening conditions could improve the identification and treatment of a variety of speech processing disorders. PMID:24286757

Simulating multiprimary LCDs on standard tri-stimulus LC displays

NASA Astrophysics Data System (ADS)

Lebowsky, Fritz; Vonneilich, Katrin; Bonse, Thomas

2008-01-01

Large-scale, direct view TV screens, in particular those based on liquid crystal technology, are beginning to use subpixel structures with more than three subpixels to implement a multi-primary display with up to six primaries. Since their input color space is likely to remain tri-stimulus RGB we first focus on some fundamental constraints. Among them, we elaborate simplified gamut mapping architectures as well as color filter geometry, transparency, and chromaticity coordinates in color space. Based on a 'display centric' RGB color space tetrahedrization combined with linear interpolation we describe a simulation framework which enables optimization for up to 7 primaries. We evaluated the performance through mapping the multi-primary design back onto a RGB LC display gamut without building a prototype multi-primary display. As long as we kept the RGB equivalent output signal within the display gamut we could analyze all desirable multi-primary configurations with regard to colorimetric variance and visually perceived quality. Not only does our simulation tool enable us to verify a novel concept it also demonstrates how carefully one needs to design a multiprimary display for LCD TV applications.

Interactions of cognitive and auditory abilities in congenitally blind individuals.

PubMed

Rokem, Ariel; Ahissar, Merav

2009-02-01

Congenitally blind individuals have been found to show superior performance in perceptual and memory tasks. In the present study, we asked whether superior stimulus encoding could account for performance in memory tasks. We characterized the performance of a group of congenitally blind individuals on a series of auditory, memory and executive cognitive tasks and compared their performance to that of sighted controls matched for age, education and musical training. As expected, we found superior verbal spans among congenitally blind individuals. Moreover, we found superior speech perception, measured by resilience to noise, and superior auditory frequency discrimination. However, when memory span was measured under conditions of equivalent speech perception, by adjusting the signal to noise ratio for each individual to the same level of perceptual difficulty (80% correct), the advantage in memory span was completely eliminated. Moreover, blind individuals did not possess any advantage in cognitive executive functions, such as manipulation of items in memory and math abilities. We propose that the short-term memory advantage of blind individuals results from better stimulus encoding, rather than from superiority at subsequent processing stages.

Classification of electronically generated phantom targets by an Atlantic bottlenose dolphin (Tursiops truncatus).

PubMed

Aubauer, R; Au, W W; Nachtigall, P E; Pawloski, D A; DeLong, C M

2000-05-01

Animal behavior experiments require not only stimulus control of the animal's behavior, but also precise control of the stimulus itself. In discrimination experiments with real target presentation, the complex interdependence between the physical dimensions and the backscattering process of an object make it difficult to extract and control relevant echo parameters separately. In other phantom-echo experiments, the echoes were relatively simple and could only simulate certain properties of targets. The echo-simulation method utilized in this paper can be used to transform any animal echolocation sound into phantom echoes of high fidelity and complexity. The developed phantom-echo system is implemented on a digital signal-processing board and gives an experimenter fully programmable control over the echo-generating process and the echo structure itself. In this experiment, the capability of a dolphin to discriminate between acoustically simulated phantom replicas of targets and their real equivalents was tested. Phantom replicas were presented in a probe technique during a materials discrimination experiment. The animal accepted the phantom echoes and classified them in the same manner as it classified real targets.

Language performance and auditory evoked fields in 2- to 5-year-old children.

PubMed

Yoshimura, Yuko; Kikuchi, Mitsuru; Shitamichi, Kiyomi; Ueno, Sanae; Remijn, Gerard B; Haruta, Yasuhiro; Oi, Manabu; Munesue, Toshio; Tsubokawa, Tsunehisa; Higashida, Haruhiro; Minabe, Yoshio

2012-02-01

Language development progresses at a dramatic rate in preschool children. As rapid temporal processing of speech signals is important in daily colloquial environments, we performed magnetoencephalography (MEG) to investigate the linkage between speech-evoked responses during rapid-rate stimulus presentation (interstimulus interval < 1 s) and language performance in 2- to 5-year-old children (n = 59). Our results indicated that syllables with this short stimulus interval evoked detectable P50m, but not N100m, in most participants, indicating a marked influence of longer neuronal refractory period for stimulation. The results of equivalent dipole estimation showed that the intensity of the P50m component in the left hemisphere was positively correlated with language performance (conceptual inference ability). The observed positive correlations were suggested to reflect the maturation of synaptic organisation or axonal maturation and myelination underlying the acquisition of linguistic abilities. The present study is among the first to use MEG to study brain maturation pertaining to language abilities in preschool children. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Sensitivity of vergence responses of 5- to 10-week-old human infants

PubMed Central

Seemiller, Eric S.; Wang, Jingyun; Candy, T. Rowan

2016-01-01

Infants have been shown to make vergence eye movements by 1 month of age to stimulation with prisms or targets moving in depth. However, little is currently understood about the threshold sensitivity of the maturing visual system to such stimulation. In this study, 5- to 10-week-old human infants and adults viewed a target moving in depth as a triangle wave of three amplitudes (1.0, 0.5, and 0.25 meter angles). Their horizontal eye position and the refractive state of both eyes were measured simultaneously. The vergence responses of the infants and adults varied at the same frequency as the stimulus at the three tested modulation amplitudes. For a typical infant of this age, the smallest amplitude is equivalent to an interocular change of approximately 2° of retinal disparity, from nearest to farthest points. The infants' accommodation responses only modulated reliably to the largest stimulus, while adults responded to all three amplitudes. Although the accommodative system appears relatively insensitive, the sensitivity of the vergence responses suggests that subtle cues are available to drive vergence in the second month after birth. PMID:26891827

Pilot study to evaluate 3 hygiene protocols on the reduction of bacterial load on the hands of veterinary staff performing routine equine physical examinations.

PubMed

Traub-Dargatz, Josie L; Weese, J Scott; Rousseau, Joyce D; Dunowska, Magdalena; Morley, Paul S; Dargatz, David A

2006-07-01

Reduction factors (RFs) for bacterial counts on examiners' hands were compared when performing a standardized equine physical examination, followed by the use of one of 3 hand-hygiene protocols (washing with soap, ethanol gel application, and chlorohexidine-ethanol application). The mean RFs were 1.29 log10 and 1.44 log10 at 2 study sites for the alcohol-gel (62% ethyl alcohol active ingredient) protocols and 1.47 log10 and 1.94 log10 at 2 study sites for the chlorhexidine-alcohol (61% ethyl alcohol plus 1% chlorhexidine active ingredients) protocols, respectively. The RFs were significantly different (P < 0.0001) between the hand-washing group and the other 2 treatment groups (the alcohol-gel and the chlorhexidine-alcohol lotion). The use of alcohol-based gels or chlorhexidine-alcohol hand hygiene protocols must still be proven effective in equine practice settings, but in this study, these protocols were equivalent or superior to hand washing for reduction in bacterial load on the hands of people after they perform routine physical examinations.

Pilot study to evaluate 3 hygiene protocols on the reduction of bacterial load on the hands of veterinary staff performing routine equine physical examinations

PubMed Central

Traub-Dargatz, Josie L.; Weese, J. Scott; Rousseau, Joyce D.; Dunowska, Magdalena; Morley, Paul S.; Dargatz, David A.

2006-01-01

Abstract Reduction factors (RFs) for bacterial counts on examiners’ hands were compared when performing a standardized equine physical examination, followed by the use of one of 3 hand-hygiene protocols (washing with soap, ethanol gel application, and chlorohexidine-ethanol application). The mean RFs were 1.29 log10 and 1.44 log10 at 2 study sites for the alcohol-gel (62% ethyl alcohol active ingredient) protocols and 1.47 log10 and 1.94 log10 at 2 study sites for the chlorhexidine-alcohol (61% ethyl alcohol plus 1% chlorhexidine active ingredients) protocols, respectively. The RFs were significantly different (P < 0.0001) between the hand-washing group and the other 2 treatment groups (the alcohol-gel and the chlorhexidine-alcohol lotion). The use of alcohol-based gels or chlorhexidine-alcohol hand hygiene protocols must still be proven effective in equine practice settings, but in this study, these protocols were equivalent or superior to hand washing for reduction in bacterial load on the hands of people after they perform routine physical examinations. PMID:16898109

Dream recall and dream content in obsessive-compulsive patients: is there a change during exposure treatment?

PubMed

Kuelz, Anne K; Stotz, Ulrike; Riemann, Dieter; Schredl, Michael; Voderholzer, Ulrich

2010-08-01

Very little is known about dreams in patients with obsessive compulsive disorder, especially regarding changes over the course of treatment with stimulus exposure and response prevention. By use of dream content analysis, 40 dreams of 9 obsessive compulsive (OC) inpatients were compared with 84 dreams of 10 matched OC outpatients and 63 dreams of 11 healthy control participants. Dream protocols of inpatients were collected at the beginning of treatment and after the first exposure exercises. Controls filled in dream protocols in respective intervals. Before treatment, dreams of patients showed significantly less positive contents than dreams of healthy controls. Under treatment with exposure, a significant reduction of OC themes was observed. The findings support the continuity hypothesis of dreaming by showing a link between day-time symptoms and OC symptoms in dreams. Contrary to expectations, however, exposure treatment does not intensify dreams.

Housing conditions and stimulus females: a robust social discrimination task for studying male rodent social recognition

PubMed Central

Macbeth, Abbe H.; Edds, Jennifer Stepp; Young, W. Scott

2010-01-01

Social recognition (SR) enables rodents to distinguish between familiar and novel conspecifics, largely through individual odor cues. SR tasks utilize the tendency for a male to sniff and interact with a novel individual more than a familiar individual. Many paradigms have been used to study the roles of the neuropeptides oxytocin and vasopressin in SR. However, inconsistencies in results have arisen within similar mouse strains, and across different paradigms and laboratories, making reliable testing of social recognition difficult. The current protocol details a novel approach that is replicable across investigators and in different strains of mice. We created a protocol that utilizes gonadally intact, singly housed females presented within corrals to group-housed males. Housing females singly prior to testing is particularly important for reliable discrimination. This methodology will be useful for studying short-term social memory in rodents, and may also be applicable for longer-term studies. PMID:19816420

Classical conditioning through auditory stimuli in Drosophila: methods and models

PubMed Central

Menda, Gil; Bar, Haim Y.; Arthur, Ben J.; Rivlin, Patricia K.; Wyttenbach, Robert A.; Strawderman, Robert L.; Hoy, Ronald R.

2011-01-01

SUMMARY The role of sound in Drosophila melanogaster courtship, along with its perception via the antennae, is well established, as is the ability of this fly to learn in classical conditioning protocols. Here, we demonstrate that a neutral acoustic stimulus paired with a sucrose reward can be used to condition the proboscis-extension reflex, part of normal feeding behavior. This appetitive conditioning produces results comparable to those obtained with chemical stimuli in aversive conditioning protocols. We applied a logistic model with general estimating equations to predict the dynamics of learning, which successfully predicts the outcome of training and provides a quantitative estimate of the rate of learning. Use of acoustic stimuli with appetitive conditioning provides both an alternative to models most commonly used in studies of learning and memory in Drosophila and a means of testing hearing in both sexes, independently of courtship responsiveness. PMID:21832129

Drug-induced conditioned place preference and aversion in mice.

PubMed

Cunningham, Christopher L; Gremel, Christina M; Groblewski, Peter A

2006-01-01

This protocol describes the equipment and methods used to establish conditioned place preference (CPP) or aversion (CPA). Place conditioning is a form of Pavlovian conditioning routinely used to measure the rewarding or aversive motivational effects of objects or experiences (e.g., abused drugs). Here, we present a place conditioning procedure that has been used extensively to study the motivational effects of ethanol and other abused drugs in mice. This protocol involves three phases: (i) habituation (or a pretest), (ii) conditioning of an association between the drug and a tactile or visual stimulus and (iii) a test that offers a choice between the drug-associated cue and a neutral cue. If the drug has motivational significance, mice will spend significantly more time (CPP) or less time (CPA) in proximity to the drug-associated cue. Potential problems in the design and interpretation of place conditioning studies are discussed. A typical experiment lasts 2 weeks.

EQUIVALENCE OF ELEMENTAL CARBON BY THERMAL/OPTICAL REFLECTANCE AND TRANSMITTANCE WITH DIFFERENT TEMPERATURE PROTOCOLS. (R831086)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

21 CFR 1311.140 - Requirements for signing a controlled substance prescription.

Code of Federal Regulations, 2010 CFR

2010-04-01

... following statement or its substantial equivalent is displayed: “By completing the two-factor authentication... above information to the pharmacy for dispensing. The two-factor authentication protocol may only be... section remain displayed, the practitioner must be prompted to complete the two-factor authentication...

Quantifying the ozone and ultraviolet benefits already achieved by the Montreal Protocol.

PubMed

Chipperfield, M P; Dhomse, S S; Feng, W; McKenzie, R L; Velders, G J M; Pyle, J A

2015-05-26

Chlorine- and bromine-containing ozone-depleting substances (ODSs) are controlled by the 1987 Montreal Protocol. In consequence, atmospheric equivalent chlorine peaked in 1993 and has been declining slowly since then. Consistent with this, models project a gradual increase in stratospheric ozone with the Antarctic ozone hole expected to disappear by ∼2050. However, we show that by 2013 the Montreal Protocol had already achieved significant benefits for the ozone layer. Using a 3D atmospheric chemistry transport model, we demonstrate that much larger ozone depletion than observed has been avoided by the protocol, with beneficial impacts on surface ultraviolet. A deep Arctic ozone hole, with column values <120 DU, would have occurred given meteorological conditions in 2011. The Antarctic ozone hole would have grown in size by 40% by 2013, with enhanced loss at subpolar latitudes. The decline over northern hemisphere middle latitudes would have continued, more than doubling to ∼15% by 2013.

Quantifying the ozone and ultraviolet benefits already achieved by the Montreal Protocol

NASA Astrophysics Data System (ADS)

Chipperfield, M. P.; Dhomse, S. S.; Feng, W.; McKenzie, R. L.; Velders, G. J. M.; Pyle, J. A.

2015-05-01

Chlorine- and bromine-containing ozone-depleting substances (ODSs) are controlled by the 1987 Montreal Protocol. In consequence, atmospheric equivalent chlorine peaked in 1993 and has been declining slowly since then. Consistent with this, models project a gradual increase in stratospheric ozone with the Antarctic ozone hole expected to disappear by ~2050. However, we show that by 2013 the Montreal Protocol had already achieved significant benefits for the ozone layer. Using a 3D atmospheric chemistry transport model, we demonstrate that much larger ozone depletion than observed has been avoided by the protocol, with beneficial impacts on surface ultraviolet. A deep Arctic ozone hole, with column values <120 DU, would have occurred given meteorological conditions in 2011. The Antarctic ozone hole would have grown in size by 40% by 2013, with enhanced loss at subpolar latitudes. The decline over northern hemisphere middle latitudes would have continued, more than doubling to ~15% by 2013.

User-independent assessment of conditioning pain modulation by cuff pressure algometry.

PubMed

Graven-Nielsen, T; Izumi, M; Petersen, K K; Arendt-Nielsen, L

2017-03-01

The use of conditioning pain modulation (CPM) is hampered by poor reproducibility and lack of user-independent paradigms. This study refined the CPM paradigm by applying user-independent cuff algometry. In 20 subjects, the CPM effect of conditioning with cuff stimulation on the arm was investigated by pain test stimuli on the contralateral leg before and in parallel with different cuff conditionings (10, 30, 60 kPa/60 s; 30, 60 kPa/10 s). As test stimulus, another cuff was inflated (1 kPa/s) until the subjects detected the pain tolerance threshold (PTT) during which the pain detection threshold (PDT) and the pressure at a pain intensity of 6 cm on a 10-cm visual analogue scale (PVAS6) were extracted. For comparison, pressure pain thresholds (PPTs) as test stimuli were recorded by the user-dependent handheld pressure algometry. Combinations of cuff locations for conditioning (pain intensity standardized) and contralateral test stimuli were additionally evaluated (leg-arm, leg-leg, arm-thigh). The test-retest reliability in two sessions 1 month apart was assessed in five CPM protocols. In all protocols, the PDT, PVAS6 and PTT increased during conditioning compared with baseline (p < 0.05). The CPM effect (i.e. conditioning minus baseline) for PVAS6, PTT and PPT increased for increasing conditioning intensities (p < 0.05). The CPM effects were not significantly different for changes in conditioning durations or conditioning/test stimulus locations. In two sessions, the CPM effects for PVAS6 and PTT assessed after 60 s of conditioning on the leg/thigh showed the highest intra-class correlations (0.47-0.73), where they were 0.04-0.6 for PPTs. The user-independent cuff algometry is reliable for CPM assessment and for supra-pain threshold test stimuli better than the user-dependent technology. A user-independent CPM technique where the conditioning is controlled by one cuff stimulation, and the test-stimulus is provided by another cuff stimulation. This study shows that cuff algometry is reliable for CPM assessment. © 2016 European Pain Federation - EFIC®.

The effects of two equal-volume training protocols upon strength, body composition and salivary hormones in male rugby union players

PubMed Central

Heke, TOL; Keogh, JWL

2016-01-01

This study examined the effects of two equal-volume resistance-training protocols upon strength, body composition and salivary hormones in male rugby union players. Using a crossover design, 24 male rugby players completed a 4-week full-body (FB) and split-body (SB) training protocol of equal volume during the competitive season. One repetition maximum (1RM) strength, body composition via skinfold measurements and salivary testosterone (T) and cortisol (C) concentrations were assessed pre and post training. The FB and SB protocols improved upper (7.3% and 7.4%) and lower body 1RM strength (7.4% and 5.4%), whilst reducing body fat (-0.9% and -0.4%) and fat mass (-5.7% and -2.1%), respectively (all p ≤ 0.021). The SB protocol elevated T (21%) and C (50%) concentrations with a higher T/C ratio (28%) after FB training (all p ≤ 0.039). The strength changes were similar, but the body composition and hormonal results differed by protocol. Slope testing on the individual responses identified positive associations (p ≤ 0.05) between T and C concentrations and absolute 1RM strength in stronger (squat 1RM = 150.5 kg), but not weaker (squat 1RM = 117.4 kg), men. A short window of training involving FB or SB protocols can improve strength and body composition in rugby players. The similar strength gains highlight training volume as a key adaptive stimulus, although the programme structure (i.e. FB or SB) did influence the body composition and hormonal outcomes. It also appears that 1RM strength is associated with individual hormonal changes and baseline strength. PMID:27274103

The effects of two equal-volume training protocols upon strength, body composition and salivary hormones in male rugby union players.

PubMed

Crewther, B T; Heke, Tol; Keogh, Jwl

2016-06-01

This study examined the effects of two equal-volume resistance-training protocols upon strength, body composition and salivary hormones in male rugby union players. Using a crossover design, 24 male rugby players completed a 4-week full-body (FB) and split-body (SB) training protocol of equal volume during the competitive season. One repetition maximum (1RM) strength, body composition via skinfold measurements and salivary testosterone (T) and cortisol (C) concentrations were assessed pre and post training. The FB and SB protocols improved upper (7.3% and 7.4%) and lower body 1RM strength (7.4% and 5.4%), whilst reducing body fat (-0.9% and -0.4%) and fat mass (-5.7% and -2.1%), respectively (all p ≤ 0.021). The SB protocol elevated T (21%) and C (50%) concentrations with a higher T/C ratio (28%) after FB training (all p ≤ 0.039). The strength changes were similar, but the body composition and hormonal results differed by protocol. Slope testing on the individual responses identified positive associations (p ≤ 0.05) between T and C concentrations and absolute 1RM strength in stronger (squat 1RM = 150.5 kg), but not weaker (squat 1RM = 117.4 kg), men. A short window of training involving FB or SB protocols can improve strength and body composition in rugby players. The similar strength gains highlight training volume as a key adaptive stimulus, although the programme structure (i.e. FB or SB) did influence the body composition and hormonal outcomes. It also appears that 1RM strength is associated with individual hormonal changes and baseline strength.

Development of a neuromuscular electrical stimulation protocol for sprint training.

PubMed

Russ, David W; Clark, Brian C; Krause, Jodi; Hagerman, Fredrick C

2012-09-01

Sprint training is associated with several beneficial adaptations in skeletal muscle, including an enhancement of sarcoplasmic reticulum (SR) Ca(2+) release. Unfortunately, several patient populations (e.g., the elderly, those with cardiac dysfunction) that might derive great benefit from sprint exercise are unlikely to tolerate it. The purpose of this report was to describe the development of a tolerable neuromuscular electrical stimulation (NMES) protocol that induces skeletal muscle adaptations similar to those observed with sprint training. Our NMES protocol was modeled after a published sprint exercise protocol and used a novel electrode configuration and stimulation sequence to provide adequate training stimulus while maintaining subject tolerance. Nine young, healthy subjects (four men) began and completed the training protocol of the knee extensor muscles. All subjects completed the protocol, with ratings of discomfort far less than those reported in studies of traditional NMES. Training induced significant increases in SR Ca(2+) release and citrate synthase activity (~16% and 32%, respectively), but SR Ca(2+) uptake did not change. The percentage of myosin heavy chain IIx isoform was decreased significantly after training. At the whole muscle level, neither central activation nor maximum voluntary isometric contraction force were significantly altered, although isometric force did exhibit a trend toward an increase (~3%, P = 0.055). Surprisingly, the NMES training produced a significant increase in muscle cross-sectional area (~3%, P = 0.04). It seems that an appropriately designed NMES protocol can mimic many of the benefits of sprint exercise training, with a low overall time commitment and training volume. These findings suggest that NMES has the potential to bring the benefits of sprint exercise to individuals who are unable to tolerate traditional sprint training.

A Confirmation of the Quench-Cryoannealing Relaxation Protocol for Identifying Reduction States of Freeze-Trapped Nitrogenase Intermediates

PubMed Central

2015-01-01

We have advanced a mechanism for nitrogenase catalysis that rests on the identification of a low-spin EPR signal (S = 1/2) trapped during turnover of a MoFe protein as the E4 state, which has accumulated four reducing equivalents as two [Fe–H–Fe] bridging hydrides. Because electrons are delivered to the MoFe protein one at a time, with the rate-limiting step being the off-rate of oxidized Fe protein, it is difficult to directly control, or know, the degree of reduction, n, of a trapped intermediate, denoted En, n = 1–8. To overcome this previously intractable problem, we introduced a quench-cryoannealing relaxation protocol for determining n of an EPR-active trapped En turnover state. The trapped “hydride” state was allowed to relax to the resting E0 state in frozen medium, which prevents additional accumulation of reducing equivalents; binding of reduced Fe protein and release of oxidized protein from the MoFe protein both are abolished in a frozen solid. Relaxation of En was monitored by periodic EPR analysis at cryogenic temperature. The protocol rests on the hypothesis that an intermediate trapped in the frozen solid can relax toward the resting state only by the release of a stable reduction product from FeMo-co. In turnover under Ar, the only product that can be released is H2, which carries two reducing equivalents. This hypothesis implicitly predicts that states that have accumulated an odd number of electrons/protons (n = 1, 3) during turnover under Ar cannot relax to E0: E3 can relax to E1, but E1 cannot relax to E0 in the frozen state. The present experiments confirm this prediction and, thus, the quench-cryoannealing protocol and our assignment of E4, the foundation of the proposed mechanism for nitrogenase catalysis. This study further gives insights into the identity of the En intermediates with high-spin EPR signals, 1b and 1c, trapped under high electron flux. PMID:24635454

Top-down guidance in visual search for facial expressions.

PubMed

Hahn, Sowon; Gronlund, Scott D

2007-02-01

Using a visual search paradigm, we investigated how a top-down goal modified attentional bias for threatening facial expressions. In two experiments, participants searched for a facial expression either based on stimulus characteristics or a top-down goal. In Experiment 1 participants searched for a discrepant facial expression in a homogenous crowd of faces. Consistent with previous research, we obtained a shallower response time (RT) slope when the target face was angry than when it was happy. In Experiment 2, participants searched for a specific type of facial expression (allowing a top-down goal). When the display included a target, we found a shallower RT slope for the angry than for the happy face search. However, when an angry or happy face was present in the display in opposition to the task goal, we obtained equivalent RT slopes, suggesting that the mere presence of an angry face in opposition to the task goal did not support the well-known angry face superiority effect. Furthermore, RT distribution analyses supported the special status of an angry face only when it was combined with the top-down goal. On the basis of these results, we suggest that a threatening facial expression may guide attention as a high-priority stimulus in the absence of a specific goal; however, in the presence of a specific goal, the efficiency of facial expression search is dependent on the combined influence of a top-down goal and the stimulus characteristics.

Brain Responses to a 6-Hz Binaural Beat: Effects on General Theta Rhythm and Frontal Midline Theta Activity

PubMed Central

Jirakittayakorn, Nantawachara; Wongsawat, Yodchanan

2017-01-01

A binaural beat is a beat phenomenon that is generated by the dichotic presentation of two almost equivalent pure tones but with slightly different frequencies. The brain responses to binaural beats remain controversial; therefore, the aim of this study was to investigate theta activity responses to a binaural beat by controlling factors affecting localization, including beat frequency, carrier tone frequency, exposure duration, and recording procedure. Exposure to a 6-Hz binaural beat on a 250 Hz carrier tone for 30 min was utilized in this study. Quantitative electroencephalography (QEEG) was utilized as the recording modality. Twenty-eight participants were divided into experimental and control groups. Emotional states were evaluated by Brunel Mood Scale (BRMUS) before and after exposing to the stimulus. The results showed that theta activity was induced in the entire cortex within 10 min of exposure to the stimulus in the experimental group. Compared to the control group, theta activity was also induced at the frontal and parietal-central regions, which included the Fz position, and left hemisphere dominance was presented for other exposure durations. The pattern recorded for 10 min of exposure appeared to be brain functions of a meditative state. Moreover, tension factor of BRUMS was decreased in experimental group compared to control group which resembled the meditation effect. Thus, a 6-Hz binaural beat on a 250 Hz carrier tone was suggested as a stimulus for inducing a meditative state. PMID:28701912

Brain Responses to a 6-Hz Binaural Beat: Effects on General Theta Rhythm and Frontal Midline Theta Activity.

PubMed

Jirakittayakorn, Nantawachara; Wongsawat, Yodchanan

2017-01-01

A binaural beat is a beat phenomenon that is generated by the dichotic presentation of two almost equivalent pure tones but with slightly different frequencies. The brain responses to binaural beats remain controversial; therefore, the aim of this study was to investigate theta activity responses to a binaural beat by controlling factors affecting localization, including beat frequency, carrier tone frequency, exposure duration, and recording procedure. Exposure to a 6-Hz binaural beat on a 250 Hz carrier tone for 30 min was utilized in this study. Quantitative electroencephalography (QEEG) was utilized as the recording modality. Twenty-eight participants were divided into experimental and control groups. Emotional states were evaluated by Brunel Mood Scale (BRMUS) before and after exposing to the stimulus. The results showed that theta activity was induced in the entire cortex within 10 min of exposure to the stimulus in the experimental group. Compared to the control group, theta activity was also induced at the frontal and parietal-central regions, which included the Fz position, and left hemisphere dominance was presented for other exposure durations. The pattern recorded for 10 min of exposure appeared to be brain functions of a meditative state. Moreover, tension factor of BRUMS was decreased in experimental group compared to control group which resembled the meditation effect. Thus, a 6-Hz binaural beat on a 250 Hz carrier tone was suggested as a stimulus for inducing a meditative state.

The Semicircular Canal Microphonic

NASA Technical Reports Server (NTRS)

Rabbitt, R. D.; Boyle, R.; Highstein, S. M.; Dalton, Bonnie P. (Technical Monitor)

2002-01-01

Present experiments were designed to quantify the alternating current (AC) component of the semicircular canal microphonic for angular motion stimulation as a function of stimulus frequency and amplitude. The oyster toadfish, Opsanus tau, was used as the experimental model. Calibrated mechanical indentation of the horizontal canal duct was used as a stimulus to generate hair-cell and afferent responses reproducing those present during head rotation. Sensitivity to polarization of the endolymph DC voltage re: perilymph was also investigated. Modulation of endolymph voltage was recorded using conventional glass electrodes and lock-in amplification over the frequency range 0.2-80 Hz. Access to the endolymph for inserting voltage recording and current passing electrodes was obtained by sectioning the anterior canal at its apex and isolating the cut ends in air. For sinusoidal stimulation below approx.10 Hz, the horizontal semicircular canal AC microphonic was nearly independent of stimulus frequency and equal to approximately 4 microV per micron indent (equivalent to approx. 1 microV per deg/s). A saturating nonlinearity decreasing the microphonic gain was present for stimuli exceeding approx.3 micron indent (approx. 12 deg/s angular velocity). The phase was not sensitive to the saturating nonlinearity. The microphonic exhibited a resonance near 30Hz consistent with basolateral current hair cell resonance observed previously in voltage-clamp records from semicircular canal hair cells. The magnitude and phase of the microphonic exhibited sensitivity to endolymphatic polarization consistent with electro-chemical reversal of hair cell transduction currents.

Sources of interference in item and associative recognition memory.

PubMed

Osth, Adam F; Dennis, Simon

2015-04-01

A powerful theoretical framework for exploring recognition memory is the global matching framework, in which a cue's memory strength reflects the similarity of the retrieval cues being matched against the contents of memory simultaneously. Contributions at retrieval can be categorized as matches and mismatches to the item and context cues, including the self match (match on item and context), item noise (match on context, mismatch on item), context noise (match on item, mismatch on context), and background noise (mismatch on item and context). We present a model that directly parameterizes the matches and mismatches to the item and context cues, which enables estimation of the magnitude of each interference contribution (item noise, context noise, and background noise). The model was fit within a hierarchical Bayesian framework to 10 recognition memory datasets that use manipulations of strength, list length, list strength, word frequency, study-test delay, and stimulus class in item and associative recognition. Estimates of the model parameters revealed at most a small contribution of item noise that varies by stimulus class, with virtually no item noise for single words and scenes. Despite the unpopularity of background noise in recognition memory models, background noise estimates dominated at retrieval across nearly all stimulus classes with the exception of high frequency words, which exhibited equivalent levels of context noise and background noise. These parameter estimates suggest that the majority of interference in recognition memory stems from experiences acquired before the learning episode. (c) 2015 APA, all rights reserved).

Developing and validating trace fear conditioning protocols in C57BL/6 mice.

PubMed

Burman, Michael A; Simmons, Cassandra A; Hughes, Miles; Lei, Lei

2014-01-30

Classical fear conditioning is commonly used to study the biology of fear, anxiety and memory. Previous research demonstrated that delay conditioning requires a neural circuit involving the amygdala, but not usually the hippocampus. Trace and contextual fear conditioning require the amygdala and hippocampus. While these paradigms were developed primarily using rat models, they are increasingly being used in mice. The current studies develop trace fear conditioning and control paradigms to allow for the assessment of trace and delay fear conditioning in C57BL/6N mice. Our initial protocol yielded clear delay and contextual conditioning. However, trace conditioning failed to differentiate from an unpaired group and was not hippocampus-dependent. These results suggested that the protocol needed to be modified to specifically accommodate trace conditioning the mice. In order to reduce unconditioned freezing and increase learning, the final protocol was developed by decreasing the intensity of the tone and by increasing the inter-trial interval. Our final protocol produced trace conditioned freezing that was significantly greater than that followed unpaired stimulus exposure and was disrupted by hippocampus lesions. A review of the literature produced 90 articles using trace conditioning in mice. Few of those articles used any kind of behavioral control group, which is required to rule out non-associative factors causing fearful behavior. Fewer used unpaired groups involving tones and shocks within a session, which is the optimal control group. Our final trace conditioning protocol can be used in future studies examining genetically modified C57BL/6N mice. Copyright © 2013 Elsevier B.V. All rights reserved.

Developing and Validating Trace Fear Conditioning Protocols in C57BL/6 Mice

PubMed Central

Burman, Michael A; Simmons, Cassandra A; Hughes, Miles; Lei, Lei

2013-01-01

Background Classical fear conditioning is commonly used to study the biology of fear, anxiety and memory. Previous research demonstrated that delay conditioning requires a neural circuit involving the amygdala, but not usually the hippocampus. Trace and contextual fear conditioning require the amygdala and hippocampus. While these paradigms were developed primarily using rat models, they are increasingly being used in mice. New Method The current studies develop trace fear conditioning and control paradigms to allow for the assessment of trace and delay fear conditioning in C57BL/6N mice. Our initial protocol yielded clear delay and contextual conditioning. However, trace conditioning failed to differentiate from an unpaired group and was not hippocampus-dependent. These results suggested that the protocol needed to be modified to specifically accommodate trace conditioning the mice. In order to reduce unconditioned freezing and increase learning, the final protocol was developed by decreasing the intensity of the tone and by increasing the inter-trial interval. Results Our final protocol produced trace conditioned freezing that was significantly greater than that followed unpaired stimulus exposure and was disrupted by hippocampus lesions. Comparison with Existing Methods A review of the literature produced 90 articles using trace conditioning in mice. Few of those articles used any kind of behavioral control group, which is required to rule out non-associative factors causing fearful behavior. Fewer used unpaired groups involving tones and shocks within a session, which is the optimal control group. Conclusions Our final trace conditioning protocol can be used in future studies examining genetically modified C57BL/6N mice. PMID:24269252

Neural correlates of the spatial and expectancy components of endogenous and stimulus-driven orienting of attention in the Posner task.

PubMed

Doricchi, Fabrizio; Macci, Enrica; Silvetti, Massimo; Macaluso, Emiliano

2010-07-01

Voluntary orienting of visual attention is conventionally measured in tasks with predictive central cues followed by frequent valid targets at the cued location and by infrequent invalid targets at the uncued location. This implies that invalid targets entail both spatial reorienting of attention and breaching of the expected spatial congruency between cues and targets. Here, we used event-related functional magnetic resonance imaging (fMRI) to separate the neural correlates of the spatial and expectancy components of both endogenous orienting and stimulus-driven reorienting of attention. We found that during endogenous orienting with predictive cues, there was a significant deactivation of the right Temporal-Parietal Junction (TPJ). We also discovered that the lack of an equivalent deactivation with nonpredictive cues was matched to drop in attentional costs and preservation of attentional benefits. The right TPJ showed equivalent responses to invalid targets following predictive and nonpredictive cues. On the contrary, infrequent-unexpected invalid targets following predictive cues specifically activated the right Middle and Inferior Frontal Gyrus (MFG-IFG). Additional comparisons with spatially neutral trials demonstrated that, independently of cue predictiveness, valid targets activate the left TPJ, whereas invalid targets activate both the left and right TPJs. These findings show that the selective right TPJ activation that is found in the comparison between invalid and valid trials results from the reciprocal cancelling of the different activations that in the left TPJ are related to the processing of valid and invalid targets. We propose that left and right TPJs provide "matching and mismatching to attentional template" signals. These signals enable reorienting of attention and play a crucial role in the updating of the statistical contingency between cues and targets.

FLIT-MLO and No. 2 fuel oil: Effects of aerosol applications to mallard eggs on hatchability and behavior of ducklings

USGS Publications Warehouse

Albers, P.H.; Heinz, G.H.

1983-01-01

FLIT-MLO and No. 2 fuel oil are sprayed on wetlands for mosquito control during spring and summer. In one experiment to assess the effects of the spraying on birds, mallard eggs were sprayed with amounts of No. 2 fuel oil equivalent to 2.34, 4.67, or 18.70 liters/ha or FLIT-MLO equivalent to 9.35, 46.75, or 140.25 liters/ha on Day 6 of incubation. In a second experiment, mallard eggs were sprayed with 9.35, 46.75, or 140.25 liters/ha of FLIT-MLO on Days 3, 6, 12, or 18 of incubation. Hatchability of eggs sprayed with the highest treatment level of each substance was significantly lower than that of controls for the first experiment. Hatchability of eggs sprayed with FLIT-MLO in the second experiment was never significantly lower than that of controls. Ducklings from the first experiment, 36-48 hr old, were cold stressed for 1 hr at 8 degrees C and then immediately tested for their ability to respond to a fright stimulus. Ducklings from the group of eggs sprayed with 140.25 liters/ha of FLIT-MLO ran a significantly shorter distance from the fright stimulus than did controls. The effects of the heaviest exposure to FLIT-MLO (140.25 liters/ha) on egg hatchability and behavior of newly hatched young are uncertain because of the contradictory results for hatching success in the two experiments. However, normal applications of FLIT-MLO (9.35-46.75 liters/ha) or No. 2 fuel oil (2.34-4.67 liters/ha) do not appear to pose a threat to the embryos of breeding birds.

The Influence of the Rebaudioside A Content of Stevia (Stevia rebaudiana Bertoni) on the Determination of Sweetness Equivalence in Bittersweet Chocolates, Using the Time-Intensity Analysis.

PubMed

Azevedo, Bruna M; Ferreira, Janaína M M; Luccas, Valdecir; Bolini, Helena M A

2016-12-01

The consumption of diet products has increased greatly in recent years. The objectives of the study were to develop a bittersweet chocolate added inulin and stevias with different rebaudioside A contents (60%, 80%, and 97%). Five chocolate samples were formulated with different sucrose concentrations to determine the ideal sucrose concentration for bittersweet chocolate. The use of just-about-right scale identified an ideal sucrose concentration of 47.5% (w/w). The sweetness equivalence in sugar-free bittersweet chocolates was determined by the time-intensity method by 14 selected and trained judges. The data collected during each session of sensory evaluation furnished the following parameters in relation to the sweet stimulus: Imax (maximum intensity recorded), Timax (time at which the maximum intensity was recorded), Area (area of time × intensity curve), and Ttot (total duration time of the stimulus). The time-intensity analysis indicated that the percentages of rebaudioside A did not interfere with the sweetness intensity of the sweetener stevia in bittersweet chocolate and there was no significant difference in the concentrations tested (0.16%, 0.22%, 0.27%) of each stevia, in relation to the parameters evaluated. In addition, the reduction in fat content did not alter the perception of the sweetness intensity of the samples. These results showed important information to research and development of chocolate products. Therefore, the use of the lowest stevia concentration tested (0.16%) is the most indicated for use, since this quantity was sufficient to reach the ideal sweetness of the product, so there was no point in adding more. © 2016 Institute of Food Technologists®.

Honeybees in a virtual reality environment learn unique combinations of colour and shape.

PubMed

Rusch, Claire; Roth, Eatai; Vinauger, Clément; Riffell, Jeffrey A

2017-10-01

Honeybees are well-known models for the study of visual learning and memory. Whereas most of our knowledge of learned responses comes from experiments using free-flying bees, a tethered preparation would allow fine-scale control of the visual stimuli as well as accurate characterization of the learned responses. Unfortunately, conditioning procedures using visual stimuli in tethered bees have been limited in their efficacy. In this study, using a novel virtual reality environment and a differential training protocol in tethered walking bees, we show that the majority of honeybees learn visual stimuli, and need only six paired training trials to learn the stimulus. We found that bees readily learn visual stimuli that differ in both shape and colour. However, bees learn certain components over others (colour versus shape), and visual stimuli are learned in a non-additive manner with the interaction of specific colour and shape combinations being crucial for learned responses. To better understand which components of the visual stimuli the bees learned, the shape-colour association of the stimuli was reversed either during or after training. Results showed that maintaining the visual stimuli in training and testing phases was necessary to elicit visual learning, suggesting that bees learn multiple components of the visual stimuli. Together, our results demonstrate a protocol for visual learning in restrained bees that provides a powerful tool for understanding how components of a visual stimulus elicit learned responses as well as elucidating how visual information is processed in the honeybee brain. © 2017. Published by The Company of Biologists Ltd.

Equivalence between entanglement and the optimal fidelity of continuous variable teleportation.

PubMed

Adesso, Gerardo; Illuminati, Fabrizio

2005-10-07

We devise the optimal form of Gaussian resource states enabling continuous-variable teleportation with maximal fidelity. We show that a nonclassical optimal fidelity of N-user teleportation networks is necessary and sufficient for N-party entangled Gaussian resources, yielding an estimator of multipartite entanglement. The entanglement of teleportation is equivalent to the entanglement of formation in a two-user protocol, and to the localizable entanglement in a multiuser one. Finally, we show that the continuous-variable tangle, quantifying entanglement sharing in three-mode Gaussian states, is defined operationally in terms of the optimal fidelity of a tripartite teleportation network.

Comparison of Bruce treadmill exercise test protocols: is ramped Bruce equal or superior to standard bruce in producing clinically valid studies for patients presenting for evaluation of cardiac ischemia or arrhythmia with body mass index equal to or greater than 30?

PubMed

Bires, Angela Macci; Lawson, Dori; Wasser, Thomas E; Raber-Baer, Donna

2013-12-01

Clinically valid cardiac evaluation via treadmill stress testing requires patients to achieve specific target heart rates and to successfully complete the cardiac examination. A comparison of the standard Bruce protocol and the ramped Bruce protocol was performed using data collected over a 1-y period from a targeted patient population with a body mass index (BMI) equal to or greater than 30 to determine which treadmill protocol provided more successful examination results. The functional capacity, metabolic equivalent units achieved, pressure rate product, and total time on the treadmill as measured for the obese patients were clinically valid and comparable to normal-weight and overweight patients (P < 0.001). Data gathered from each protocol demonstrated that the usage of the ramped Bruce protocol achieved more consistent results in comparison across all BMI groups in achieving 80%-85% of their age-predicted maximum heart rate. This study did not adequately establish that the ramped Bruce protocol was superior to the standard Bruce protocol for the examination of patients with a BMI equal to or greater than 30.

12 CFR 365.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2013 CFR

2013-01-01

... OF GENERAL POLICY REAL ESTATE LENDING STANDARDS Registration of Residential Mortgage Loan Originators... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees...) identified in paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify...

12 CFR 365.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2014 CFR

2014-01-01

... OF GENERAL POLICY REAL ESTATE LENDING STANDARDS Registration of Residential Mortgage Loan Originators... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees...) identified in paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify...

12 CFR 365.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2011 CFR

2011-01-01

... OF GENERAL POLICY REAL ESTATE LENDING STANDARDS Registration of Residential Mortgage Loan Originators... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees...) identified in paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify...

12 CFR 365.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2012 CFR

2012-01-01

... OF GENERAL POLICY REAL ESTATE LENDING STANDARDS Registration of Residential Mortgage Loan Originators... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees...) identified in paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify...

29 CFR 1910.1001 - Asbestos.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... The designation of a material as “PACM” may be rebutted pursuant to paragraph (j)(8) of this section... level as demonstrated by a statistically valid protocol; and (C) The equivalent method is documented and... PACM are in excess of the TWA and/or excursion limit prescribed in paragraph (c) of this section. (2...

29 CFR 1910.1001 - Asbestos.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... The designation of a material as “PACM” may be rebutted pursuant to paragraph (j)(8) of this section... level as demonstrated by a statistically valid protocol; and (C) The equivalent method is documented and... PACM are in excess of the TWA and/or excursion limit prescribed in paragraph (c) of this section. (2...

Real-time Electrophysiology: Using Closed-loop Protocols to Probe Neuronal Dynamics and Beyond

PubMed Central

Linaro, Daniele; Couto, João; Giugliano, Michele

2015-01-01

Experimental neuroscience is witnessing an increased interest in the development and application of novel and often complex, closed-loop protocols, where the stimulus applied depends in real-time on the response of the system. Recent applications range from the implementation of virtual reality systems for studying motor responses both in mice1 and in zebrafish2, to control of seizures following cortical stroke using optogenetics3. A key advantage of closed-loop techniques resides in the capability of probing higher dimensional properties that are not directly accessible or that depend on multiple variables, such as neuronal excitability4 and reliability, while at the same time maximizing the experimental throughput. In this contribution and in the context of cellular electrophysiology, we describe how to apply a variety of closed-loop protocols to the study of the response properties of pyramidal cortical neurons, recorded intracellularly with the patch clamp technique in acute brain slices from the somatosensory cortex of juvenile rats. As no commercially available or open source software provides all the features required for efficiently performing the experiments described here, a new software toolbox called LCG5 was developed, whose modular structure maximizes reuse of computer code and facilitates the implementation of novel experimental paradigms. Stimulation waveforms are specified using a compact meta-description and full experimental protocols are described in text-based configuration files. Additionally, LCG has a command-line interface that is suited for repetition of trials and automation of experimental protocols. PMID:26132434

A shortened protocol for assessing cognitive bias in rats.

PubMed

Brydges, Nichola M; Hall, Lynsey

2017-07-15

Reliable measurement of affective state in animals is a significant goal of animal welfare. Such measurements would also improve the validity of pre-clinical mental health research which relies on animal models. However, at present, affective states in animals are inaccessible to direct measurement. In humans, changes in cognitive processing can give reliable indications of emotional state. Therefore, similar techniques are increasingly being used to gain proxy measures of affective states in animals. In particular, the 'cognitive bias' assay has gained popularity in recent years. Major disadvantages of this technique include length of time taken for animals to acquire the task (typically several weeks), negative experiences associated with task training, and issues of motivation. Here we present a shortened cognitive bias protocol using only positive reinforcers which must actively be responded to. The protocol took an average of 4days to complete, and produced similar results to previous, longer methods (minimum 30days). Specifically, rats housed in standard laboratory conditions demonstrated negative cognitive biases when presented with ambiguous stimuli, and took longer to make a decision when faced with an ambiguous stimulus. Compared to previous methods, this protocol is significantly shorter (average 4days vs. minimum 30days), utilises only positive reinforcers to avoid inducing negative affective states, and requires active responses to all cues, avoiding potential confounds of motivational state. We have successfully developed a shortened cognitive bias protocol, suitable for use with laboratory rats. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

How to select equivalent and complimentary reversed phase liquid chromatography columns from column characterization databases.

PubMed

Borges, Endler M

2014-01-07

Three RP-LC column characterization protocols [Tanaka et al. (1989), Snyder et al. (PQRI, 2002), and NIST SRM 870 (2000)] were evaluated using both Euclidian distance and Principal Components Analysis to evaluate effectiveness at identifying equivalent columns. These databases utilize specific chromatographic properties such as hydrophobicity, hydrogen bonding, shape/steric selectivity, and ion exchange capacity of stationary phases. The chromatographic parameters of each test were shown to be uncorrelated. Despite this, the three protocols were equally successful in identifying similar and/or dissimilar stationary phases. The veracity of the results has been supported by some real life pharmaceutical separations. The use of Principal Component Analysis to identify similar/dissimilar phases appears to have some limitations in terms of loss of information. In contrast, the use of Euclidian distances is a much more convenient and reliable approach. The use of auto scaled data is favoured over the use of weighted factors as the former data transformation is less affected by the addition or removal of columns from the database. The use of these free databases and their corresponding software tools shown to be valid for identifying similar columns with equivalent chromatographic selectivity and retention as a "backup column". In addition, dissimilar columns with complimentary chromatographic selectivity can be identified for method development screening strategies. Copyright © 2013 Elsevier B.V. All rights reserved.

Model-Driven Analysis of Eyeblink Classical Conditioning Reveals the Underlying Structure of Cerebellar Plasticity and Neuronal Activity.

PubMed

Antonietti, Alberto; Casellato, Claudia; D'Angelo, Egidio; Pedrocchi, Alessandra

The cerebellum plays a critical role in sensorimotor control. However, how the specific circuits and plastic mechanisms of the cerebellum are engaged in closed-loop processing is still unclear. We developed an artificial sensorimotor control system embedding a detailed spiking cerebellar microcircuit with three bidirectional plasticity sites. This proved able to reproduce a cerebellar-driven associative paradigm, the eyeblink classical conditioning (EBCC), in which a precise time relationship between an unconditioned stimulus (US) and a conditioned stimulus (CS) is established. We challenged the spiking model to fit an experimental data set from human subjects. Two subsequent sessions of EBCC acquisition and extinction were recorded and transcranial magnetic stimulation (TMS) was applied on the cerebellum to alter circuit function and plasticity. Evolutionary algorithms were used to find the near-optimal model parameters to reproduce the behaviors of subjects in the different sessions of the protocol. The main finding is that the optimized cerebellar model was able to learn to anticipate (predict) conditioned responses with accurate timing and success rate, demonstrating fast acquisition, memory stabilization, rapid extinction, and faster reacquisition as in EBCC in humans. The firing of Purkinje cells (PCs) and deep cerebellar nuclei (DCN) changed during learning under the control of synaptic plasticity, which evolved at different rates, with a faster acquisition in the cerebellar cortex than in DCN synapses. Eventually, a reduced PC activity released DCN discharge just after the CS, precisely anticipating the US and causing the eyeblink. Moreover, a specific alteration in cortical plasticity explained the EBCC changes induced by cerebellar TMS in humans. In this paper, for the first time, it is shown how closed-loop simulations, using detailed cerebellar microcircuit models, can be successfully used to fit real experimental data sets. Thus, the changes of the model parameters in the different sessions of the protocol unveil how implicit microcircuit mechanisms can generate normal and altered associative behaviors.The cerebellum plays a critical role in sensorimotor control. However, how the specific circuits and plastic mechanisms of the cerebellum are engaged in closed-loop processing is still unclear. We developed an artificial sensorimotor control system embedding a detailed spiking cerebellar microcircuit with three bidirectional plasticity sites. This proved able to reproduce a cerebellar-driven associative paradigm, the eyeblink classical conditioning (EBCC), in which a precise time relationship between an unconditioned stimulus (US) and a conditioned stimulus (CS) is established. We challenged the spiking model to fit an experimental data set from human subjects. Two subsequent sessions of EBCC acquisition and extinction were recorded and transcranial magnetic stimulation (TMS) was applied on the cerebellum to alter circuit function and plasticity. Evolutionary algorithms were used to find the near-optimal model parameters to reproduce the behaviors of subjects in the different sessions of the protocol. The main finding is that the optimized cerebellar model was able to learn to anticipate (predict) conditioned responses with accurate timing and success rate, demonstrating fast acquisition, memory stabilization, rapid extinction, and faster reacquisition as in EBCC in humans. The firing of Purkinje cells (PCs) and deep cerebellar nuclei (DCN) changed during learning under the control of synaptic plasticity, which evolved at different rates, with a faster acquisition in the cerebellar cortex than in DCN synapses. Eventually, a reduced PC activity released DCN discharge just after the CS, precisely anticipating the US and causing the eyeblink. Moreover, a specific alteration in cortical plasticity explained the EBCC changes induced by cerebellar TMS in humans. In this paper, for the first time, it is shown how closed-loop simulations, using detailed cerebellar microcircuit models, can be successfully used to fit real experimental data sets. Thus, the changes of the model parameters in the different sessions of the protocol unveil how implicit microcircuit mechanisms can generate normal and altered associative behaviors.

Shortcuts to adiabaticity by counterdiabatic driving for trapped-ion displacement in phase space

PubMed Central

An, Shuoming; Lv, Dingshun; del Campo, Adolfo; Kim, Kihwan

2016-01-01

The application of adiabatic protocols in quantum technologies is severely limited by environmental sources of noise and decoherence. Shortcuts to adiabaticity by counterdiabatic driving constitute a powerful alternative that speed up time-evolution while mimicking adiabatic dynamics. Here we report the experimental implementation of counterdiabatic driving in a continuous variable system, a shortcut to the adiabatic transport of a trapped ion in phase space. The resulting dynamics is equivalent to a ‘fast-motion video' of the adiabatic trajectory. The robustness of this protocol is shown to surpass that of competing schemes based on classical local controls and Fourier optimization methods. Our results demonstrate that shortcuts to adiabaticity provide a robust speedup of quantum protocols of wide applicability in quantum technologies. PMID:27669897

The clinical effectiveness of concise cognitive behavioral therapy with or without pharmacotherapy for depressive and anxiety disorders; a pragmatic randomized controlled equivalence trial in clinical practice.

PubMed

Meuldijk, D; Carlier, I V E; van Vliet, I M; van Veen, T; Wolterbeek, R; van Hemert, A M; Zitman, F G

2016-03-01

Depressive and anxiety disorders contribute to a high disease burden. This paper investigates whether concise formats of cognitive behavioral- and/or pharmacotherapy are equivalent with longer standard care in the treatment of depressive and/or anxiety disorders in secondary mental health care. A pragmatic randomized controlled equivalence trial was conducted at five Dutch outpatient Mental Healthcare Centers (MHCs) of the Regional Mental Health Provider (RMHP) 'Rivierduinen'. Patients (aged 18-65 years) with a mild to moderate anxiety and/or depressive disorder, were randomly allocated to concise or standard care. Data were collected at baseline, 3, 6 and 12 months by Routine Outcome Monitoring (ROM). Primary outcomes were the Brief Symptom Inventory (BSI) and the Web Screening Questionnaire (WSQ). We used Generalized Estimating Equations (GEE) to assess outcomes. Between March 2010 and December 2012, 182 patients, were enrolled (n=89 standard care; n=93 concise care). Both intention-to-treat and per-protocol analyses demonstrated equivalence of concise care and standard care at all time points. Severity of illness reduced, and both treatments improved patient's general health status and subdomains of quality of life. Moreover, in concise care, the beneficial effects started earlier. Concise care has the potential to be a feasible and promising alternative to longer standard secondary mental health care in the treatment of outpatients with a mild to moderate depressive and/or anxiety disorder. For future research, we recommend adhering more strictly to the concise treatment protocols to further explore the beneficial effects of the concise treatment. The study is registered in the Netherlands Trial Register, number NTR2590. Clinicaltrials.gov identifier: NCT01643642. Copyright © 2015 Elsevier Inc. All rights reserved.

Encoding of the amplitude modulation of pulsatile electrical stimulation in the feline cochlear nucleus by neurons in the inferior colliculus; effects of stimulus pulse rate

NASA Astrophysics Data System (ADS)

McCreery, Douglas; Han, Martin; Pikov, Victor; Yadav, Kamal; Pannu, Satinderpall

2013-10-01

Objectives. Persons without a functional auditory nerve cannot benefit from cochlear implants, but some hearing can be restored by an auditory brainstem implant (ABI) with stimulating electrodes implanted on the surface of the cochlear nucleus (CN). Most users benefit from their ABI, but speech recognition tends to be poorer than for users of cochlear implants. Psychophysical studies suggest that poor modulation detection may contribute to the limited performance of ABI users. In a cat model, we determined how the pulse rate of the electrical stimulus applied within or on the CN affects temporal and rate encoding of amplitude modulation (AM) by neurons in the central nucleus of the inferior colliculus (ICC). Approach. Stimulating microelectrodes were implanted chronically in and on the cats' CN, and multi-site recording microelectrodes were implanted chronically into the ICC. Encoding of AM pulse trains by neurons in the ICC was characterized as vector strength (VS), the synchrony of neural activity with the AM, and as the mean rate of neuronal action potentials (neuronal spike rate (NSR)). Main results. For intranuclear microstimulation, encoding of AM as VS was up to 3 dB greater when stimulus pulse rate was increased from 250 to 500 pps, but only for neuronal units with low best acoustic frequencies, and when the electrical stimulation was modulated at low frequencies (10-20 Hz). For stimulation on the surface of the CN, VS was similar at 250 and 500 pps, and the dynamic range of the VS was reduced for pulse rates greater than 250 pps. Modulation depth was encoded strongly as VS when the maximum stimulus amplitude was held constant across a range of modulation depth. This ‘constant maximum’ protocol allows enhancement of modulation depth while preserving overall dynamic range. However, modulation depth was not encoded as strongly as NSR. Significance. The findings have implications for improved sound processors for present and future ABIs. The performance of ABIs may benefit from using pulse rates greater than those presently used in most ABIs, and by sound processing strategies that enhance the modulation depth of the electrical stimulus while preserving dynamic range.

Cortical processing of tactile stimuli applied in quick succession across the fingertips: temporal evolution of dipole sources revealed by magnetoencephalography.

PubMed

Karageorgiou, Elissaios; Koutlas, Ioannis G; Alonso, Aurelio A; Leuthold, Arthur C; Lewis, Scott M; Georgopoulos, Apostolos P

2008-08-01

We used magnetoencephalography (MEG) in 10 healthy human subjects to study cortical responses to tactile stimuli applied to the fingertips of digits 2-5 of the right hand. Each stimulus lasted 50 ms and was produced by air-driven elastic membranes. Four-hundred stimuli were delivered on each finger in three temporal patterns (conditions). In the "Discrete" condition, stimuli were applied to each finger repetitively with an interstimulus interval (ISI) of 1-2 s. In the "Continuous" condition, stimuli were applied to the fingers sequentially as four-stimulus trains with zero ISI and 1-2 s intervening between trains. Finally, in the "Gap" condition, stimuli were applied as in the Continuous condition but with an ISI of 50 ms. A sensation of tactile motion across fingers (digit 2 --> digit 5) was reported by all subjects in the Continuous and Gap conditions. Cortical responses were extracted as single equivalent current dipoles over a period of 1 s following stimulus onset. In all three conditions, initial responses in left primary somatosensory cortex (SI) were observed ~20 to 50 ms after stimulus onset and were followed by additional left SI responses and bilateral responses in the secondary somatosensory cortex (SII). In addition, in the Continuous and Gap conditions, there was an activation of the precentral gyrus, the temporal aspects of which depended on the temporal relation of the administered stimuli, as follows. An ISI of 0 ms led to activation of the precentral gyrus shortly after the second stimulation, whereas an ISI of 50 ms led to activation of the precentral gyrus after the third stimulation. The current findings support results from previous studies on temporal activity patterns in SI and SII, verify the participation of the precentral gyrus during tactile motion perception and, in addition, reveal aspects of integration of sequential sensory stimulations over nonadjacent areas as well as temporal activity patterns in the postcentral and precentral gyri.

Taste-dependent sociophobia: when food and company do not mix.

PubMed

Guitton, Matthieu J; Klin, Yael; Dudai, Yadin

2008-08-22

Using a combination of the paradigm of conditioned taste aversion (CTA) and of the paradigm of social interactions, we report here that in the rat, eating while anxious may result in long-term alterations in social behavior. In the conventional CTA, the subject learns to associate a tastant (the conditioned stimulus, CS) with delayed toxicosis (an unconditioned stimulus, UCS) to yield taste aversion (the conditioned response, CR). However, the association of taste with delayed negative internal states that could generate CRs that are different from taste aversion should not be neglected. Such associations may contribute to the ontogenesis, reinforcement and symptoms of some types of taste- and food-related disorders. We have recently reported that a delayed anxiety-like state, induced by the anxiogenic drug meta-chlorophenylpiperazine (mCPP), can specifically associate with taste to produce CTA. We now show that a similar protocol results in a marked lingering impairment in social interactions in response to the conditioned taste. This is hence a learned situation in which food and company do not mix well.

Radiation dose equivalent to stowaways in vehicles.

PubMed

Khan, Siraj M; Nicholas, Paul E; Terpilak, Michael S

2004-05-01

The U.S. Bureau of Customs and Border Protection has deployed a large number of non-intrusive inspection (NII) systems at land border crossings and seaports throughout the United States to inspect cars, trucks, and sea containers. These NII systems use x rays and gamma rays for the detection of contraband. Unfortunately, undocumented aliens infrequently stow away in these same conveyances to illegally enter the United States. It is extremely important that the radiation dose equivalent imparted to these stowaways be within acceptable limits. This paper discusses the issues involved and describes a protocol the U.S. Bureau of Customs and Border Protection has used in a study to measure and document these levels. The results of this study show that the radiation dose equivalent to the stowaways from the deployed NII systems is negligibly small and does not pose a health hazard.

Continuous-variable measurement-device-independent quantum key distribution with virtual photon subtraction

NASA Astrophysics Data System (ADS)

Zhao, Yijia; Zhang, Yichen; Xu, Bingjie; Yu, Song; Guo, Hong

2018-04-01

The method of improving the performance of continuous-variable quantum key distribution protocols by postselection has been recently proposed and verified. In continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocols, the measurement results are obtained from untrusted third party Charlie. There is still not an effective method of improving CV-MDI QKD by the postselection with untrusted measurement. We propose a method to improve the performance of coherent-state CV-MDI QKD protocol by virtual photon subtraction via non-Gaussian postselection. The non-Gaussian postselection of transmitted data is equivalent to an ideal photon subtraction on the two-mode squeezed vacuum state, which is favorable to enhance the performance of CV-MDI QKD. In CV-MDI QKD protocol with non-Gaussian postselection, two users select their own data independently. We demonstrate that the optimal performance of the renovated CV-MDI QKD protocol is obtained with the transmitted data only selected by Alice. By setting appropriate parameters of the virtual photon subtraction, the secret key rate and tolerable excess noise are both improved at long transmission distance. The method provides an effective optimization scheme for the application of CV-MDI QKD protocols.

12 CFR 34.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2011 CFR

2011-01-01

....103 Section 34.103 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY REAL... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees... paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify their identity...

12 CFR 34.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2013 CFR

2013-01-01

....103 Section 34.103 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY REAL... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees... paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify their identity...

12 CFR 34.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2012 CFR

2012-01-01

....103 Section 34.103 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY REAL... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees... paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify their identity...

12 CFR 34.103 - Registration of mortgage loan originators.

Code of Federal Regulations, 2014 CFR

2014-01-01

....103 Section 34.103 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY REAL... not act as mortgage loan originators unless the bank has 10 or fewer full time or equivalent employees... paragraphs (e)(1)(i)(E) and (F) of this section must comply with Registry protocols to verify their identity...

Actigraphy-based sleep parameters during the reinstatement of methamphetamine self-administration in rhesus monkeys.

PubMed

Berro, Laís F; Andersen, Monica L; Tufik, Sergio; Howell, Leonard L

2016-04-01

The objective of this study was to investigate nighttime activity of nonhuman primates during extinction and cue- and drug-primed reinstatement of methamphetamine self-administration. Adult rhesus monkeys (Macaca mulatta; n = 5) self-administered methamphetamine (0.01 mg/kg/injection, i.v.) under a fixed-ratio 20 schedule of reinforcement. Saline infusions were then substituted for methamphetamine and stimulus light (drug-conditioned stimulus presented during drug self-administration) withheld until subjects reached extinction criteria. Drug- and cue-induced reinstatement effects were evaluated after i.v. noncontingent priming injections of methamphetamine (0.03, 0.1, or 0.3 mg/kg). Activity-based sleep measures were evaluated with Actiwatch monitors a week before (baseline nighttime activity parameters) and throughout the protocol. Although methamphetamine self-administration did not significantly affect nighttime activity compared to baseline, sleeplike parameters were improved during extinction compared to self-administration maintenance. Priming injection of 0.1 mg/kg methamphetamine, but not 0.03 or 0.3 mg/kg, induced significant reinstatement effects. These behavioral responses were accompanied by nighttime outcomes, with increased sleep fragmentation and decreased sleep efficiency in the night following 0.1 mg/kg methamphetamine-induced reinstatement. In the absence of both drug and drug-paired cues (extinction conditions), nighttime activity decreased compared to self-administration maintenance. Additionally, effective reinstatement conditions impaired sleeplike measures. Our data indicate that the reintroduction of the stimulus light as a drug-paired cue increased nighttime activity. (c) 2016 APA, all rights reserved).

Genotypic Influence on Aversive Conditioning in Honeybees, Using a Novel Thermal Reinforcement Procedure

PubMed Central

Junca, Pierre; Carcaud, Julie; Moulin, Sibyle; Garnery, Lionel; Sandoz, Jean-Christophe

2014-01-01

In Pavlovian conditioning, animals learn to associate initially neutral stimuli with positive or negative outcomes, leading to appetitive and aversive learning respectively. The honeybee (Apis mellifera) is a prominent invertebrate model for studying both versions of olfactory learning and for unraveling the influence of genotype. As a queen bee mates with about 15 males, her worker offspring belong to as many, genetically-different patrilines. While the genetic dependency of appetitive learning is well established in bees, it is not the case for aversive learning, as a robust protocol was only developed recently. In the original conditioning of the sting extension response (SER), bees learn to associate an odor (conditioned stimulus - CS) with an electric shock (unconditioned stimulus - US). This US is however not a natural stimulus for bees, which may represent a potential caveat for dissecting the genetics underlying aversive learning. We thus first tested heat as a potential new US for SER conditioning. We show that thermal stimulation of several sensory structures on the bee’s body triggers the SER, in a temperature-dependent manner. Moreover, heat applied to the antennae, mouthparts or legs is an efficient US for SER conditioning. Then, using microsatellite analysis, we analyzed heat sensitivity and aversive learning performances in ten worker patrilines issued from a naturally inseminated queen. We demonstrate a strong influence of genotype on aversive learning, possibly indicating the existence of a genetic determinism of this capacity. Such determinism could be instrumental for efficient task partitioning within the hive. PMID:24828422

Theoretical Limitations on Functional Imaging Resolution in Auditory Cortex

PubMed Central

Chen, Thomas L.; Watkins, Paul V.; Barbour, Dennis L.

2010-01-01

Functional imaging can reveal detailed organizational structure in cerebral cortical areas, but neuronal response features and local neural interconnectivity can influence the resulting images, possibly limiting the inferences that can be drawn about neural function. Discerning the fundamental principles of organizational structure in the auditory cortex of multiple species has been somewhat challenging historically both with functional imaging and with electrophysiology. A possible limitation affecting any methodology using pooled neuronal measures may be the relative distribution of response selectivity throughout the population of auditory cortex neurons. One neuronal response type inherited from the cochlea, for example, exhibits a receptive field that increases in size (i.e., decreases in selectivity) at higher stimulus intensities. Even though these neurons appear to represent a minority of auditory cortex neurons, they are likely to contribute disproportionately to the activity detected in functional images, especially if intense sounds are used for stimulation. To evaluate the potential influence of neuronal subpopulations upon functional images of primary auditory cortex, a model array representing cortical neurons was probed with virtual imaging experiments under various assumptions about the local circuit organization. As expected, different neuronal subpopulations were activated preferentially under different stimulus conditions. In fact, stimulus protocols that can preferentially excite selective neurons, resulting in a relatively sparse activation map, have the potential to improve the effective resolution of functional auditory cortical images. These experimental results also make predictions about auditory cortex organization that can be tested with refined functional imaging experiments. PMID:20079343

Distortion product otoacoustic emissions: comparison of sequential vs. simultaneous presentation of primary tones.

PubMed

Kumar, U Ajith; Maruthy, Sandeep; Chandrakant, Vishwakarma

2009-03-01

Distortion product otoacoustic emissions are one form of evoked otoacoustic emissions. DPOAEs provide the frequency specific information about the hearing status in mid and high frequency regions. But in most screening protocols TEOAEs are preferred as it requires less time compared to DPOAE. This is because, in DPOAE each stimulus is presented one after the other and responses are analyzed. Grason and Stadler Incorporation 60 (GSI-60) offer simultaneous presentation of four sets of primary tones at a time and checks for the DPOAE. In this mode of presentation, all the pairs are presented at a time and following that response is extracted separately whereas, in sequential mode primaries are presented in orderly fashion one after the other. In this article simultaneous and sequential protocols were used to compare the Distortion product otoacoustic emission amplitude, noise floor and administration time in individuals with normal hearing and mild sensori-neural (SN) hearing loss. In simultaneous protocols four sets of primary tones (i.e. 8 tones) were presented together whereas, in sequential presentation mode one set of primary tones was presented each time. Simultaneous protocol was completed in less than half the time required for the completion of sequential protocol. Two techniques yielded similar results at frequencies above 1000 Hz only in normal hearing group. In SN hearing loss group simultaneous presentation yielded signifi cantly higher noise floors and distortion product amplitudes. This result challenges the use of simultaneous presentation technique in neonatal hearing screening programmes and on other pathologies. This discrepancy between two protocols may be due to some changes in biomechanical process in the cochlear and/or due to higher distortion/noise produced by the system during the simultaneous presentation mode.

Comparison of Different Forms of Exercise Training in Patients With Cardiac Disease: Where Does High-Intensity Interval Training Fit?

PubMed

Gayda, Mathieu; Ribeiro, Paula A B; Juneau, Martin; Nigam, Anil

2016-04-01

In this review, we discuss the most recent forms of exercise training available to patients with cardiac disease and their comparison or their combination (or both) during short- and long-term (phase II and III) cardiac rehabilitation programs. Exercise training modalities to be discussed include inspiratory muscle training (IMT), resistance training (RT), continuous aerobic exercise training (CAET), and high-intensity interval training (HIIT). Particular emphasis is placed on HIIT compared or combined (or both) with other forms such as CAET or RT. For example, IMT combined with CAET was shown to be superior to CAET alone for improving functional capacity, ventilatory function, and quality of life in patients with chronic heart failure. Similarly, RT combined with CAET was shown to optimize benefits with respect to functional capacity, muscle function, and quality of life. Furthermore, in recent years, HIIT has emerged as an alternative or complementary (or both) exercise modality to CAET, providing equivalent if not superior benefits to conventional continuous aerobic training with respect to aerobic fitness, cardiovascular function, quality of life, efficiency, safety, tolerance, and exercise adherence in both short- and long-term training studies. Finally, short-interval HIIT was shown to be useful in the initiation and improvement phases of cardiac rehabilitation, whereas moderate- or longer-interval (or both) HIIT protocols appear to be more appropriate for the improvement and maintenance phases because of their high physiological stimulus. We now propose progressive models of exercise training (phases II-III) for patients with cardiac disease, including a more appropriate application of HIIT based on the scientific literature in the context of a multimodal cardiac rehabilitation program. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Automatic segmentation of the hippocampus for preterm neonates from early-in-life to term-equivalent age.

PubMed

Guo, Ting; Winterburn, Julie L; Pipitone, Jon; Duerden, Emma G; Park, Min Tae M; Chau, Vann; Poskitt, Kenneth J; Grunau, Ruth E; Synnes, Anne; Miller, Steven P; Mallar Chakravarty, M

2015-01-01

The hippocampus, a medial temporal lobe structure central to learning and memory, is particularly vulnerable in preterm-born neonates. To date, segmentation of the hippocampus for preterm-born neonates has not yet been performed early-in-life (shortly after birth when clinically stable). The present study focuses on the development and validation of an automatic segmentation protocol that is based on the MAGeT-Brain (Multiple Automatically Generated Templates) algorithm to delineate the hippocampi of preterm neonates on their brain MRIs acquired at not only term-equivalent age but also early-in-life. First, we present a three-step manual segmentation protocol to delineate the hippocampus for preterm neonates and apply this protocol on 22 early-in-life and 22 term images. These manual segmentations are considered the gold standard in assessing the automatic segmentations. MAGeT-Brain, automatic hippocampal segmentation pipeline, requires only a small number of input atlases and reduces the registration and resampling errors by employing an intermediate template library. We assess the segmentation accuracy of MAGeT-Brain in three validation studies, evaluate the hippocampal growth from early-in-life to term-equivalent age, and study the effect of preterm birth on the hippocampal volume. The first experiment thoroughly validates MAGeT-Brain segmentation in three sets of 10-fold Monte Carlo cross-validation (MCCV) analyses with 187 different groups of input atlases and templates. The second experiment segments the neonatal hippocampi on 168 early-in-life and 154 term images and evaluates the hippocampal growth rate of 125 infants from early-in-life to term-equivalent age. The third experiment analyzes the effect of gestational age (GA) at birth on the average hippocampal volume at early-in-life and term-equivalent age using linear regression. The final segmentations demonstrate that MAGeT-Brain consistently provides accurate segmentations in comparison to manually derived gold standards (mean Dice's Kappa > 0.79 and Euclidean distance <1.3 mm between centroids). Using this method, we demonstrate that the average volume of the hippocampus is significantly different (p < 0.0001) in early-in-life (621.8 mm(3)) and term-equivalent age (958.8 mm(3)). Using these differences, we generalize the hippocampal growth rate to 38.3 ± 11.7 mm(3)/week and 40.5 ± 12.9 mm(3)/week for the left and right hippocampi respectively. Not surprisingly, younger gestational age at birth is associated with smaller volumes of the hippocampi (p = 0.001). MAGeT-Brain is capable of segmenting hippocampi accurately in preterm neonates, even at early-in-life. Hippocampal asymmetry with a larger right side is demonstrated on early-in-life images, suggesting that this phenomenon has its onset in the 3rd trimester of gestation. Hippocampal volume assessed at the time of early-in-life and term-equivalent age is linearly associated with GA at birth, whereby smaller volumes are associated with earlier birth.

Automatic segmentation of the hippocampus for preterm neonates from early-in-life to term-equivalent age

PubMed Central

Guo, Ting; Winterburn, Julie L.; Pipitone, Jon; Duerden, Emma G.; Park, Min Tae M.; Chau, Vann; Poskitt, Kenneth J.; Grunau, Ruth E.; Synnes, Anne; Miller, Steven P.; Mallar Chakravarty, M.

2015-01-01

Introduction The hippocampus, a medial temporal lobe structure central to learning and memory, is particularly vulnerable in preterm-born neonates. To date, segmentation of the hippocampus for preterm-born neonates has not yet been performed early-in-life (shortly after birth when clinically stable). The present study focuses on the development and validation of an automatic segmentation protocol that is based on the MAGeT-Brain (Multiple Automatically Generated Templates) algorithm to delineate the hippocampi of preterm neonates on their brain MRIs acquired at not only term-equivalent age but also early-in-life. Methods First, we present a three-step manual segmentation protocol to delineate the hippocampus for preterm neonates and apply this protocol on 22 early-in-life and 22 term images. These manual segmentations are considered the gold standard in assessing the automatic segmentations. MAGeT-Brain, automatic hippocampal segmentation pipeline, requires only a small number of input atlases and reduces the registration and resampling errors by employing an intermediate template library. We assess the segmentation accuracy of MAGeT-Brain in three validation studies, evaluate the hippocampal growth from early-in-life to term-equivalent age, and study the effect of preterm birth on the hippocampal volume. The first experiment thoroughly validates MAGeT-Brain segmentation in three sets of 10-fold Monte Carlo cross-validation (MCCV) analyses with 187 different groups of input atlases and templates. The second experiment segments the neonatal hippocampi on 168 early-in-life and 154 term images and evaluates the hippocampal growth rate of 125 infants from early-in-life to term-equivalent age. The third experiment analyzes the effect of gestational age (GA) at birth on the average hippocampal volume at early-in-life and term-equivalent age using linear regression. Results The final segmentations demonstrate that MAGeT-Brain consistently provides accurate segmentations in comparison to manually derived gold standards (mean Dice's Kappa > 0.79 and Euclidean distance <1.3 mm between centroids). Using this method, we demonstrate that the average volume of the hippocampus is significantly different (p < 0.0001) in early-in-life (621.8 mm3) and term-equivalent age (958.8 mm3). Using these differences, we generalize the hippocampal growth rate to 38.3 ± 11.7 mm3/week and 40.5 ± 12.9 mm3/week for the left and right hippocampi respectively. Not surprisingly, younger gestational age at birth is associated with smaller volumes of the hippocampi (p = 0.001). Conclusions MAGeT-Brain is capable of segmenting hippocampi accurately in preterm neonates, even at early-in-life. Hippocampal asymmetry with a larger right side is demonstrated on early-in-life images, suggesting that this phenomenon has its onset in the 3rd trimester of gestation. Hippocampal volume assessed at the time of early-in-life and term-equivalent age is linearly associated with GA at birth, whereby smaller volumes are associated with earlier birth. PMID:26740912

Comparison of bandwidths in the inferior colliculus and the auditory nerve. II: Measurement using a temporally manipulated stimulus.

PubMed

Mc Laughlin, Myles; Chabwine, Joelle Nsimire; van der Heijden, Marcel; Joris, Philip X

2008-10-01

To localize low-frequency sounds, humans rely on an interaural comparison of the temporally encoded sound waveform after peripheral filtering. This process can be compared with cross-correlation. For a broadband stimulus, after filtering, the correlation function has a damped oscillatory shape where the periodicity reflects the filter's center frequency and the damping reflects the bandwidth (BW). The physiological equivalent of the correlation function is the noise delay (ND) function, which is obtained from binaural cells by measuring response rate to broadband noise with varying interaural time delays (ITDs). For monaural neurons, delay functions are obtained by counting coincidences for varying delays across spike trains obtained to the same stimulus. Previously, we showed that BWs in monaural and binaural neurons were similar. However, earlier work showed that the damping of delay functions differs significantly between these two populations. Here, we address this paradox by looking at the role of sensitivity to changes in interaural correlation. We measured delay and correlation functions in the cat inferior colliculus (IC) and auditory nerve (AN). We find that, at a population level, AN and IC neurons with similar characteristic frequencies (CF) and BWs can have different responses to changes in correlation. Notably, binaural neurons often show compression, which is not found in the AN and which makes the shape of delay functions more invariant with CF at the level of the IC than at the AN. We conclude that binaural sensitivity is more dependent on correlation sensitivity than has hitherto been appreciated and that the mechanisms underlying correlation sensitivity should be addressed in future studies.

Alternating between pro- and antisaccades: switch-costs manifest via decoupling the spatial relations between stimulus and response.

PubMed

Heath, Matthew; Gillen, Caitlin; Samani, Ashna

2016-03-01

Antisaccades are a nonstandard task requiring a response mirror-symmetrical to the location of a target. The completion of an antisaccade has been shown to delay the reaction time (RT) of a subsequent prosaccade, whereas the converse switch elicits a null RT cost (i.e., the unidirectional prosaccade switch-cost). The present study sought to determine whether the prosaccade switch-cost arises from low-level interference specific to the sensory features of a target (i.e., modality-dependent) or manifests via the high-level demands of dissociating the spatial relations between stimulus and response (i.e., modality-independent). Participants alternated between pro- and antisaccades wherein the target associated with the response alternated between visual and auditory modalities. Thus, the present design involved task-switch (i.e., switching from a pro- to antisaccade and vice versa) and modality-switch (i.e., switching from a visual to auditory target and vice versa) trials as well as their task- and modality-repetition counterparts. RTs were longer for modality-switch than modality-repetition trials. Notably, however, modality-switch trials did not nullify or lessen the unidirectional prosaccade switch-cost; that is, the magnitude of the RT cost for task-switch prosaccades was equivalent across modality-switch and modality-repetition trials. Thus, competitive interference within a sensory modality does not contribute to the unidirectional prosaccade switch-cost. Instead, the modality-independent findings evince that dissociating the spatial relations between stimulus and response instantiates a high-level and inertially persistent nonstandard task-set that impedes the planning of a subsequent prosaccade.

Delivery of nicotine in an extract of a smokeless tobacco product reduces its reinforcement-attenuating and discriminative stimulus effects in rats

PubMed Central

Harris, Andrew C.; Stepanov, Irina; Pentel, Paul R.; LeSage, Mark G.

2012-01-01

Rationale Animal models of tobacco addiction rely on administration of nicotine alone or nicotine combined with isolated constituents. Models using tobacco extracts derived from tobacco products and containing a range of tobacco constituents might more accurately simulate tobacco exposure in humans. Objective To compare the effects of nicotine alone and an aqueous smokeless tobacco extract in several addiction-related animal behavioral models. Methods Nicotine alone and nicotine dose-equivalent concentrations of extract were compared in terms of their acute effects on intracranial self-stimulation (ICSS) thresholds, discriminative stimulus effects, and effects on locomotor activity. Results Similar levels of nicotine and minor alkaloids were achieved using either artificial saliva or saline for extraction, supporting the clinical relevance of the saline extracts used in these studies. Extract produced reinforcement-enhancing (ICSS threshold-decreasing) effects similar to those of nicotine alone at low to moderate nicotine doses, but reduced reinforcement-attenuating (ICSS threshold-increasing) effects at a high nicotine dose. In rats trained to discriminate nicotine alone from saline, intermediate extract doses did not substitute for the training dose as well as nicotine alone. Locomotor stimulant effects and nicotine distribution to brain were similar following administration of extract or nicotine alone. Conclusions The reinforcement-attenuating and discriminative stimulus effects of nicotine delivered in an extract of a commercial smokeless tobacco product differed from those of nicotine alone. Extracts of tobacco products may be useful for evaluating the abuse liability of those products and understanding the role of non-nicotine constituents in tobacco addiction. PMID:21960181

Delivery of nicotine in an extract of a smokeless tobacco product reduces its reinforcement-attenuating and discriminative stimulus effects in rats.

PubMed

Harris, Andrew C; Stepanov, Irina; Pentel, Paul R; Lesage, Mark G

2012-04-01

Animal models of tobacco addiction rely on administration of nicotine alone or nicotine combined with isolated constituents. Models using tobacco extracts derived from tobacco products and containing a range of tobacco constituents might more accurately simulate tobacco exposure in humans. To compare the effects of nicotine alone and an aqueous smokeless tobacco extract in several addiction-related animal behavioral models. Nicotine alone and nicotine dose-equivalent concentrations of extract were compared in terms of their acute effects on intracranial self-stimulation (ICSS) thresholds, discriminative stimulus effects, and effects on locomotor activity. Similar levels of nicotine and minor alkaloids were achieved using either artificial saliva or saline for extraction, supporting the clinical relevance of the saline extracts used in these studies. Extract produced reinforcement-enhancing (ICSS threshold-decreasing) effects similar to those of nicotine alone at low to moderate nicotine doses, but reduced reinforcement-attenuating (ICSS threshold-increasing) effects at a high nicotine dose. In rats trained to discriminate nicotine alone from saline, intermediate extract doses did not substitute for the training dose as well as nicotine alone. Locomotor stimulant effects and nicotine distribution to brain were similar following administration of extract or nicotine alone. The reinforcement-attenuating and discriminative stimulus effects of nicotine delivered in an extract of a commercial smokeless tobacco product differed from those of nicotine alone. Extracts of tobacco products may be useful for evaluating the abuse liability of those products and understanding the role of non-nicotine constituents in tobacco addiction.

Latent vulnerability in cognitive performance following chronic cocaine self-administration in rhesus monkeys

PubMed Central

Porter, Jessica N.; Gurnsey, Kate; Jedema, Hank P.; Bradberry, Charles W.

2012-01-01

Rationale Cocaine use is associated with cognitive impairment which impacts treatment outcome. A clearer understanding of those deficits, and whether particular environments exacerbate them, is needed. Objectives This study evaluated whether previously observed domain-specific cognitive deficits persisted following a three month cessation from chronic cocaine self-administration, as well as the impact of novel and cocaine-associated attentional distractors. Methods Control and experimental groups of monkeys performed stimulus discrimination, stimulus reversal, and delayed match-to-sample (DMS) tasks. After establishing post-cocaine baseline performance, we examined general distractibility in both groups, using brief novel distractors counterbalanced across each task. After testing the novel distractor, an identical approach was used for exposure to an appetitive distractor previously associated with cocaine in the experimental group, or water in the control group. Results Post-administration baseline performance was equivalent between groups on all tasks. In the cocaine group, stimulus discrimination was unaffected by either distractor, whereas reversal performance was disrupted by both the novel and appetitive distractors. DMS performance was impaired in the cocaine group in the presence of the novel distractor. The control group’s performance was not affected by the presentation of either distractor on any task. Conclusion Our results reveal that despite normalized performance between groups, there exists in the cocaine group a domain-specific latent vulnerability of cognitive performance to impairment by environmental distractors. The pattern of vulnerability recapitulates the frank impairments seen in drug free animals during an active self-administration phase. A greater impact of the cocaine-associated distractor over the novel one was not observed. PMID:23108938

Latent vulnerability in cognitive performance following chronic cocaine self-administration in rhesus monkeys.

PubMed

Porter, Jessica N; Gurnsey, Kate; Jedema, Hank P; Bradberry, Charles W

2013-03-01

Cocaine use is associated with cognitive impairment which impacts treatment outcome. A clearer understanding of those deficits, and whether particular environments exacerbate them, is needed. This study evaluated whether previously observed domain-specific cognitive deficits persisted following a 3-month cessation from chronic cocaine self-administration, as well as the impact of novel and cocaine-associated attentional distractors. Control and experimental groups of monkeys performed stimulus discrimination, stimulus reversal, and delayed match-to-sample (DMS) tasks. After establishing post-cocaine baseline performance, we examined general distractibility in both groups, using brief novel distractors counterbalanced across each task. After testing the novel distractor, an identical approach was used for exposure to an appetitive distractor previously associated with cocaine in the experimental group or water in the control group. Post-administration baseline performance was equivalent between groups on all tasks. In the cocaine group, stimulus discrimination was unaffected by either distractor, whereas reversal performance was disrupted by both the novel and appetitive distractors. DMS performance was impaired in the cocaine group in the presence of the novel distractor. The control group's performance was not affected by the presentation of either distractor on any task. Our results reveal that despite normalized performance between groups, there exists in the cocaine group a domain-specific latent vulnerability of cognitive performance to impairment by environmental distractors. The pattern of vulnerability recapitulates the frank impairments seen in drug-free animals during an active self-administration phase. A greater impact of the cocaine-associated distractor over the novel one was not observed.

Quantifying the ozone and ultraviolet benefits already achieved by the Montreal Protocol

PubMed Central

Chipperfield, M. P.; Dhomse, S. S.; Feng, W.; McKenzie, R. L.; Velders, G.J.M.; Pyle, J. A.

2015-01-01

Chlorine- and bromine-containing ozone-depleting substances (ODSs) are controlled by the 1987 Montreal Protocol. In consequence, atmospheric equivalent chlorine peaked in 1993 and has been declining slowly since then. Consistent with this, models project a gradual increase in stratospheric ozone with the Antarctic ozone hole expected to disappear by ∼2050. However, we show that by 2013 the Montreal Protocol had already achieved significant benefits for the ozone layer. Using a 3D atmospheric chemistry transport model, we demonstrate that much larger ozone depletion than observed has been avoided by the protocol, with beneficial impacts on surface ultraviolet. A deep Arctic ozone hole, with column values <120 DU, would have occurred given meteorological conditions in 2011. The Antarctic ozone hole would have grown in size by 40% by 2013, with enhanced loss at subpolar latitudes. The decline over northern hemisphere middle latitudes would have continued, more than doubling to ∼15% by 2013. PMID:26011106

The World Already Avoided: Quantifying the Ozone Benefits Achieved by the Montreal Protocol

NASA Astrophysics Data System (ADS)

Chipperfield, Martyn; Dhomse, Sandip; Feng, Wuhu; McKenzie, Richard; Velders, Guus; Pyle, John

2015-04-01

Chlorine and bromine-containing ozone-depleting substances (ODSs) are controlled by the 1987 Montreal Protocol. In consequence, atmospheric equivalent chlorine peaked in 1993 and has been declining slowly since then. Consistent with this, models project a gradual increase in stratospheric ozone with the Antarctic Ozone Hole expected to disappear by ~2050. However, we show that by 2014 the Montreal Protocol has already achieved significant benefits for the ozone layer. Using an off-line 3-D atmospheric chemistry model, we demonstrate that much larger ozone depletion than observed has been avoided by the protocol, with benefits for surface UV and climate. A deep Arctic Ozone Hole, with column values <120 DU, would have occurred given the meteorological conditions in 2011. The Antarctic Ozone Hole would have grown in size by 40% by 2013, with enhanced loss at subpolar latitudes. The ozone decline over northern hemisphere middle latitudes would have continued, more than doubling to ~15% by 2013.

Forced-Choice Assessment of Work-Related Maladaptive Personality Traits: Preliminary Evidence From an Application of Thurstonian Item Response Modeling.

PubMed

Guenole, Nigel; Brown, Anna A; Cooper, Andrew J

2018-06-01

This article describes an investigation of whether Thurstonian item response modeling is a viable method for assessment of maladaptive traits. Forced-choice responses from 420 working adults to a broad-range personality inventory assessing six maladaptive traits were considered. The Thurstonian item response model's fit to the forced-choice data was adequate, while the fit of a counterpart item response model to responses to the same items but arranged in a single-stimulus design was poor. Monotrait heteromethod correlations indicated corresponding traits in the two formats overlapped substantially, although they did not measure equivalent constructs. A better goodness of fit and higher factor loadings for the Thurstonian item response model, coupled with a clearer conceptual alignment to the theoretical trait definitions, suggested that the single-stimulus item responses were influenced by biases that the independent clusters measurement model did not account for. Researchers may wish to consider forced-choice designs and appropriate item response modeling techniques such as Thurstonian item response modeling for personality questionnaire applications in industrial psychology, especially when assessing maladaptive traits. We recommend further investigation of this approach in actual selection situations and with different assessment instruments.

Further evidence of auditory extinction in aphasia.

PubMed

Marshall, Rebecca Shisler; Basilakos, Alexandra; Love-Myers, Kim

2013-02-01

Preliminary research (Shisler, 2005) suggests that auditory extinction in individuals with aphasia (IWA) may be connected to binding and attention. In this study, the authors expanded on previous findings on auditory extinction to determine the source of extinction deficits in IWA. Seventeen IWA (M(age) = 53.19 years) and 17 neurologically intact controls (M(age) = 55.18 years) participated. Auditory stimuli were spoken letters presented in a free-field listening environment. Stimuli were presented in single-stimulus stimulation (SSS) or double-simultaneous stimulation (DSS) trials across 5 conditions designed to determine whether extinction is related to binding, inefficient attention resource allocation, or overall deficits in attention. All participants completed all experimental conditions. Significant extinction was demonstrated only by IWA when sounds were different, providing further evidence of auditory extinction. However, binding requirements did not appear to influence the IWA's performance. Results indicate that, for IWA, auditory extinction may not be attributed to a binding deficit or inefficient attention resource allocation because of equivalent performance across all 5 conditions. Rather, overall attentional resources may be influential. Future research in aphasia should explore the effect of the stimulus presentation in addition to the continued study of attention treatment.

Reconstruction of audio waveforms from spike trains of artificial cochlea models

PubMed Central

Zai, Anja T.; Bhargava, Saurabh; Mesgarani, Nima; Liu, Shih-Chii

2015-01-01

Spiking cochlea models describe the analog processing and spike generation process within the biological cochlea. Reconstructing the audio input from the artificial cochlea spikes is therefore useful for understanding the fidelity of the information preserved in the spikes. The reconstruction process is challenging particularly for spikes from the mixed signal (analog/digital) integrated circuit (IC) cochleas because of multiple non-linearities in the model and the additional variance caused by random transistor mismatch. This work proposes an offline method for reconstructing the audio input from spike responses of both a particular spike-based hardware model called the AEREAR2 cochlea and an equivalent software cochlea model. This method was previously used to reconstruct the auditory stimulus based on the peri-stimulus histogram of spike responses recorded in the ferret auditory cortex. The reconstructed audio from the hardware cochlea is evaluated against an analogous software model using objective measures of speech quality and intelligibility; and further tested in a word recognition task. The reconstructed audio under low signal-to-noise (SNR) conditions (SNR < –5 dB) gives a better classification performance than the original SNR input in this word recognition task. PMID:26528113

Bridging the Gap: Understanding Eye Movements and Attentional Mechanisms is Key to Improving Amblyopia Treatment

NASA Astrophysics Data System (ADS)

Gambacorta, Christina Grace

Amblyopia is a developmental visual disorder resulting in sensory, motor and attentional deficits, including delays in both saccadic and manual reaction time. It is unclear whether this delay is due to differences in sensory processing of the stimulus, or the processes required to dis-engage/shift/re-engage attention when moving the eye from fixation to a saccadic target. In the first experiment we compare asymptotic saccadic and manual reaction times between the two eyes, using equivalent stimulus strength to account for differences in sensory processing. In a follow-up study, we modulate RT by removing the fixation dot, which is thought to release spatial attention at the fovea, and reduces reaction time in normal observers. Finally, we discuss the implications for these findings on future amblyopic treatment, specifically dichoptic video game playing. Playing videogames may help engage the attentional network, leading to greater improvements than traditional treatment of patching the non- amblyopic eye. Further, when treatment involves both eyes, fixation stability may be improved during the therapeutic intervention, yielding a better outcome than just playing a video game with a patch over the non-amblyopic eye.

[Multiple mere exposure effect: category evaluation measured in the Go/No-go association task (GNAT)].

PubMed

Kawakami, Naoaki; Yoshida, Fujio

2011-12-01

The effect on likability of multiple subliminal exposures to the same person was investigated. Past studies on the mere exposure effect indicated a correlation between the frequency of repeated exposure to the same stimulus and likability. We proposed that exposure to various stimuli of the same person would have a stronger effect on likability. Participants were subliminally exposed to photographs of a person's face taken from seven angles (multi-angle-exposure) three times each (Experiment 1), or photographs of a person with seven facial expressions (multi-expression-exposure) three times each (Experiment 2). Then, the likability toward the exposed person was measured using the Go/No-go Association Task. The results indicated that the effect of the multiple exposures from various angles was equivalent to exposure to only one full-face photograph shown 21 times (Experiment 1). Moreover, likability was significantly higher in the case of exposure to various facial expressions than for exposure to only a single facial expression (Experiment 2). The results suggest that exposure to various stimuli in a category is more effective than repeated exposure to a single stimulus for increasing likability.

Inattentional deafness in music.

PubMed

Koreimann, Sabrina; Gula, Bartosz; Vitouch, Oliver

2014-01-01

While inattentional blindness is a modern classic in attention and perception research, analogous phenomena of inattentional deafness have been widely neglected. We here present the first investigation of inattentional deafness in and with music under controlled experimental conditions. Inattentional deafness in music is defined as the inability to consciously perceive an unexpected musical stimulus when attention is focused on a certain facet of the piece. Participants listened to a modification of the first 1'50″ of Richard Strauss' Thus Spake Zarathustra; while the control group just listened, the experimental group had to count the number of timpani beats. An e-guitar solo served as the unexpected event. In Study 1, experimental data from n = 115 participants were analyzed. Non-musicians were compared with musicians to investigate the impact of expertise. In Study 2 (n = 47), the scope of the inattentional deafness effect was investigated with a more salient unexpected stimulus. Results demonstrate an inattentional deafness effect under dynamic musical conditions. Quite unexpectedly, the effect was structurally equivalent even for musicians. Our findings clearly show that sustained inattentional deafness exists in the musical realm, in close correspondence to inattentional blindness with dynamic visual stimuli.

Interval timing in children: effects of auditory and visual pacing stimuli and relationships with reading and attention variables.

PubMed

Birkett, Emma E; Talcott, Joel B

2012-01-01

Motor timing tasks have been employed in studies of neurodevelopmental disorders such as developmental dyslexia and ADHD, where they provide an index of temporal processing ability. Investigations of these disorders have used different stimulus parameters within the motor timing tasks that are likely to affect performance measures. Here we assessed the effect of auditory and visual pacing stimuli on synchronised motor timing performance and its relationship with cognitive and behavioural predictors that are commonly used in the diagnosis of these highly prevalent developmental disorders. Twenty-one children (mean age 9.6 years) completed a finger tapping task in two stimulus conditions, together with additional psychometric measures. As anticipated, synchronisation to the beat (ISI 329 ms) was less accurate in the visually paced condition. Decomposition of timing variance indicated that this effect resulted from differences in the way that visual and auditory paced tasks are processed by central timekeeping and associated peripheral implementation systems. The ability to utilise an efficient processing strategy on the visual task correlated with both reading and sustained attention skills. Dissociations between these patterns of relationship across task modality suggest that not all timing tasks are equivalent.

European Train Control System: A Case Study in Formal Verification

NASA Astrophysics Data System (ADS)

Platzer, André; Quesel, Jan-David

Complex physical systems have several degrees of freedom. They only work correctly when their control parameters obey corresponding constraints. Based on the informal specification of the European Train Control System (ETCS), we design a controller for its cooperation protocol. For its free parameters, we successively identify constraints that are required to ensure collision freedom. We formally prove the parameter constraints to be sharp by characterizing them equivalently in terms of reachability properties of the hybrid system dynamics. Using our deductive verification tool KeYmaera, we formally verify controllability, safety, liveness, and reactivity properties of the ETCS protocol that entail collision freedom. We prove that the ETCS protocol remains correct even in the presence of perturbation by disturbances in the dynamics. We verify that safety is preserved when a PI controlled speed supervision is used.

Training response inhibition to reduce food consumption: Mechanisms, stimulus specificity and appropriate training protocols.

PubMed

Adams, Rachel C; Lawrence, Natalia S; Verbruggen, Frederick; Chambers, Christopher D

2017-02-01

Training individuals to inhibit their responses towards unhealthy foods has been shown to reduce food intake relative to a control group. Here we aimed to further explore these effects by investigating the role of stimulus devaluation, training protocol, and choice of control group. Restrained eaters received either inhibition or control training using a modified version of either the stop-signal or go/no-go task. Following training we measured implicit attitudes towards food (Study 1) and food consumption (Studies 1 and 2). In Study 1 we used a modified stop-signal training task with increased demands on top-down control (using a tracking procedure and feedback to maintain competition between the stop and go processes). With this task, we found no evidence for an effect of training on implicit attitudes or food consumption, with Bayesian inferential analyses revealing substantial evidence for the null hypothesis. In Study 2 we removed the feedback in the stop-signal training to increase the rate of successful inhibition and revealed a significant effect of both stop-signal and go/no-go training on food intake (compared to double-response and go training, respectively) with a greater difference in consumption in the go/no-go task, compared with the stop-signal task. However, results from an additional passive control group suggest that training effects could be partly caused by increased consumption in the go control group whereas evidence for reduced consumption in the inhibition groups was inconclusive. Our findings therefore support evidence that inhibition training tasks with higher rates of inhibition accuracy are more effective, but prompt caution for interpreting the efficacy of laboratory-based inhibition training as an intervention for behaviour change. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Flicker-defined form perimetry in glaucoma patients.

PubMed

Horn, Folkert K; Kremers, Jan; Mardin, Christian Y; Jünemann, Anselm G; Adler, Werner; Tornow, Ralf P

2015-03-01

To assess the potential of flicker-defined form (FDF) perimetry to detect functional loss in patient groups with beginning glaucoma, and to evaluate the dynamic range of the FDF stimulus in individual patients and at individual test positions. FDF perimetry and standard automated perimetry (SAP) were performed at identical test locations (adapted G1 protocol) in 60 healthy subjects and 111 glaucoma patients. All patients showed glaucomatous optic disc appearance. Grouping within the glaucoma cohort was based on SAP-performance: 33 "preperimetric" open-angle glaucoma (OAG) patients, 28 "borderline" OAG (focal defects and SAP-mean defect (MD) <2 dB), 33 "early" OAG (SAP-MD < 5 dB), 17 "advanced" OAG. All participants were experienced in psychophysical and perimetric tests. Defect values and the areas under receiver operating characteristic curves (ROC) in patient groups were statistically compared. The values of FDF-MD in the preperimetric, borderline, and early OAG group were 2.7 ± 3.4 dB, 5.5 ± 2.6 dB, and 8.5 ± 3.4 dB respectively (all significantly above normal). The percentage of patients exceeding normal FDF-MD was 27.3 %, 60.7 %, and 87.9 % respectively. The age-adjusted FDF-mean defect (MD) of the G1X-protocol was not significantly correlated with refractive error, lens opacity, pupil size, or gender. Occurrence of ceiling effects (inability to detect targets at highest contrast) showed a high correlation with visual field losses (R = 0.72, p < 0.001). Local analysis indicates that SAP losses exceeding 5 dB could not be distinguished with the FDF technique. The FDF stimulus was able to detect beginning glaucoma damage. Patients with SAP-MD values exceeding 5 dB should be monitored with conventional perimetry because of its larger dynamic range.

Comparison of the efficiency of rat papillary muscles during afterloaded isotonic contractions and contractions with sinusoidal length changes.

PubMed

Mellors, L J; Gibbs, C L; Barclay, C J

2001-05-01

The results of previous studies suggest that the maximum mechanical efficiency of rat papillary muscles is lower during a contraction protocol involving sinusoidal length changes than during one involving afterloaded isotonic contractions. The aim of this study was to compare directly the efficiency of isolated rat papillary muscle preparations in isotonic and sinusoidal contraction protocols. Experiments were performed in vitro (27 degrees C) using left ventricular papillary muscles from adult rats. Each preparation performed three contraction protocols: (i) low-frequency afterloaded isotonic contractions (10 twitches at 0.2 Hz), (ii) sinusoidal length change contractions with phasic stimulation (40 twitches at 2 Hz) and (iii) high-frequency afterloaded isotonic contractions (40 twitches at 2 Hz). The first two protocols resembled those used in previous studies and the third combined the characteristics of the first two. The parameters for each protocol were adjusted to those that gave maximum efficiency. For the afterloaded isotonic protocols, the afterload was set to 0.3 of the maximum developed force. The sinusoidal length change protocol incorporated a cycle amplitude of +/-5% resting length and a stimulus phase of -10 degrees. Measurements of force output, muscle length change and muscle temperature change were used to calculate the work and heat produced during and after each protocol. Net mechanical efficiency was defined as the proportion of the energy (enthalpy) liberated by the muscle that appeared as work. The efficiency in the low-frequency, isotonic contraction protocol was 21.1+/-1.4% (mean +/- s.e.m., N=6) and that in the sinusoidal protocol was 13.2+/-0.7%, consistent with previous results. This difference was not due to the higher frequency or greater number of twitches because efficiency in the high-frequency, isotonic protocol was 21.5+/-1.0%. Although these results apparently confirm that efficiency is protocol-dependent, additional experiments designed to measure work output unambiguously indicated that the method used to calculate work output in isotonic contractions overestimated actual work output. When net work output, which excludes work done by parallel elastic elements, rather than total work output was used to determine efficiency in afterloaded isotonic contractions, efficiency was similar to that for sinusoidal contractions. The maximum net mechanical efficiency of rat papillary muscles performing afterloaded isotonic or sinusoidal length change contractions was between 10 and 15%.

Organ dose measurement using Optically Stimulated Luminescence Detector (OSLD) during CT examination

NASA Astrophysics Data System (ADS)

Yusuf, Muhammad; Alothmany, Nazeeh; Abdulrahman Kinsara, Abdulraheem

2017-10-01

This study provides detailed information regarding the imaging doses to patient radiosensitive organs from a kilovoltage computed tomography (CT) scan procedure using OSLD. The study reports discrepancies between the measured dose and the calculated dose from the ImPACT scan, as well as a comparison with the dose from a chest X-ray radiography procedure. OSLDs were inserted in several organs, including the brain, eyes, thyroid, lung, heart, spinal cord, breast, spleen, stomach, liver and ovaries, of the RANDO phantom. Standard clinical scanning protocols were used for each individual site, including the brain, thyroid, lung, breast, stomach, liver and ovaries. The measured absorbed doses were then compared with the simulated dose obtained from the ImPACT scan. Additionally, the equivalent doses for each organ were calculated and compared with the dose from a chest X-ray radiography procedure. Absorbed organ doses measured by OSLD in the RANDO phantom of up to 17 mGy depend on the organ scanned and the scanning protocols used. A maximum 9.82% difference was observed between the target organ dose measured by OSLD and the results from the ImPACT scan. The maximum equivalent organ dose measured during this experiment was equal to 99.899 times the equivalent dose from a chest X-ray radiography procedure. The discrepancies between the measured dose with the OSLD and the calculated dose from the ImPACT scan were within 10%. This report recommends the use of OSLD for measuring the absorbed organ dose during CT examination.

Simplified antibiotic regimens for treatment of clinical severe infection in the outpatient setting when referral is not possible for young infants in Pakistan (Simplified Antibiotic Therapy Trial [SATT]): a randomised, open-label, equivalence trial.

PubMed

Mir, Fatima; Nisar, Imran; Tikmani, Shiyam S; Baloch, Benazir; Shakoor, Sadia; Jehan, Fyezah; Ahmed, Imran; Cousens, Simon; Zaidi, Anita K M

2017-02-01

Parenteral antibiotic therapy for young infants (aged 0-59 days) with suspected sepsis is sometimes not available or feasible in countries with high neonatal mortality. Outpatient treatment could save lives in such settings. We aimed to assess the equivalence of two simplified antibiotic regimens, comprising fewer injections and oral rather than parenteral administration, compared with a reference treatment for young infants with clinical severe infection. We undertook the Simplified Antibiotic Therapy Trial (SATT), a three-arm, randomised, open-label, equivalence trial in five communities in Karachi, Pakistan. We enrolled young infants (aged 0-59 days) who either presented at a primary health-care clinic or were identified by a community health worker with signs of clinical severe infection. We included infants who were not critically ill and whose family refused admission. We randomly assigned infants to either intramuscular procaine benzylpenicillin and gentamicin once a day for 7 days (reference); oral amoxicillin twice daily and intramuscular gentamicin once a day for 7 days; or intramuscular procaine benzylpenicillin and gentamicin once a day for 2 days followed by oral amoxicillin twice daily for 5 days. The primary outcome was treatment failure within 7 days of enrolment and the primary analysis was per protocol. We judged experimental treatments as efficacious as the reference if the upper bound of the 95% CI for the difference in treatment failure was less than 5·0. This trial is registered at ClinicalTrials.gov, number NCT01027429. Between Jan 1, 2010, and Dec 26, 2013, 2780 infants were deemed eligible for the trial, of whom 2453 (88%) were enrolled. Because of inadequate clinical follow-up or treatment adherence, 2251 infants were included in the per-protocol analysis. 820 infants (747 per protocol) were assigned the reference treatment of procaine benzylpenicillin and gentamicin, 816 (751 per protocol) were allocated amoxicillin and gentamicin, and 817 (753 per protocol) were assigned procaine benzylpenicillin, gentamicin, and amoxicillin. Treatment failure within 7 days of enrolment was reported in 90 (12%) infants who received procaine benzylpenicillin and gentamicin (reference), 76 (10%) of those given amoxicillin and gentamicin (risk difference with reference -1·9, 95% CI -5·1 to 1·3), and 99 (13%) of those treated with procaine benzylpenicillin, gentamicin, and amoxicillin (risk difference with reference 1·1, -2·3 to 4·5). Two simplified antibiotic regimens requiring fewer injections are equivalent to a reference treatment for young infants with signs of clinical severe infection but without signs of critical illness. The use of these simplified regimens has the potential to increase access to treatment for sick young infants who cannot be referred to hospital. The Saving Newborn Lives initiative of Save the Children, through support from the Bill & Melinda Gates, and by WHO and USAID. Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license. Published by Elsevier Ltd.. All rights reserved.

Establishing Substantial Equivalence: Metabolomics

NASA Astrophysics Data System (ADS)

Beale, Michael H.; Ward, Jane L.; Baker, John M.

Modern ‘metabolomic’ methods allow us to compare levels of many structurally diverse compounds in an automated fashion across a large number of samples. This technology is ideally suited to screening of populations of plants, including trials where the aim is the determination of unintended effects introduced by GM. A number of metabolomic methods have been devised for the determination of substantial equivalence. We have developed a methodology, using [1H]-NMR fingerprinting, for metabolomic screening of plants and have applied it to the study of substantial equivalence of field-grown GM wheat. We describe here the principles and detail of that protocol as applied to the analysis of flour generated from field plots of wheat. Particular emphasis is given to the downstream data processing and comparison of spectra by multivariate analysis, from which conclusions regarding metabolome changes due to the GM can be assessed against the background of natural variation due to environment.

76 FR 58288 - International Maritime Organization Guidelines for Exhaust Gas Cleaning Systems for Marine...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-20

... Pollution by Ships, 1973 as modified by the Protocol of 1978 (MARPOL) if such a system should be considered an equivalent that would be at least as effective in reducing sulfur oxide emissions as the... Maritime Organization (IMO) for exhaust gas cleaning systems for marine engines to remove sulfur oxide...

24 CFR 3285.402 - Ground anchor installations.

Code of Federal Regulations, 2011 CFR

2011-04-01

... least equivalent to that provided by a coating of zinc on steel of not less than 0.30 oz./ft.2 of... recognized testing protocol. (2) Tie-down straps. A 11/4 inch x 0.035 inch or larger steel strapping conforming to ASTM D 3953—97, Standard Specification for Strapping, Flat Steel and Seals (incorporated by...

A Failure to Communicate

ERIC Educational Resources Information Center

Fredette, Michelle

2011-01-01

In April, Asia officially ran out of Internet Protocol (IP) version 4 addresses--the computer equivalent of running out of telephone numbers. Over the next couple of years, the rest of the world will also run dry. Yet, unlike the Y2K bug that had some people convinced the sky would fall, this particular problem is generating little more than tired…

Phenotyping sensory nerve endings in vitro in the mouse

PubMed Central

Zimmermann, Katharina; Hein, Alexander; Hager, Ulrich; Kaczmarek, Jan Stefan; Turnquist, Brian P; Clapham, David E; Reeh, Peter W

2014-01-01

This protocol details methods to identify and record from cutaneous primary afferent axons in an isolated mammalian skin–saphenous nerve preparation. The method is based on extracellular recordings of propagated action potentials from single-fiber receptive fields. Cutaneous nerve endings show graded sensitivities to various stimulus modalities that are quantified by adequate and controlled stimulation of the superfused skin with heat, cold, touch, constant punctate pressure or chemicals. Responses recorded from single-fibers are comparable with those obtained in previous in vivo experiments on the same species. We describe the components and the setting-up of the basic equipment of a skin–nerve recording station (few days), the preparation of the skin and the adherent saphenous nerve in the mouse (15–45 min) and the isolation and recording of neurons (approximately 1–3 h per recording). In addition, stimulation techniques, protocols to achieve single-fiber recordings, issues of data acquisition and action potential discrimination are discussed in detail. PMID:19180088

Maintaining ocular safety with light exposure, focusing on devices for optogenetic stimulation

PubMed Central

Yan, Boyuan; Vakulenko, Maksim; Min, Seok-Hong; Hauswirth, William W.; Nirenberg, Sheila

2016-01-01

Optogenetics methods are rapidly being developed as therapeutic tools for treating neurological diseases, in particular, retinal degenerative diseases. A critical component of the development is testing the safety of the light stimulation used to activate the optogenetic proteins. While the stimulation needs to be sufficient to produce neural responses in the targeted retinal cell class, it also needs to be below photochemical and photothermal limits known to cause ocular damage. The maximal permissible exposure is determined by a variety of factors, including wavelength, exposure duration, visual angle, pupil size, pulse width, pulse pattern, and repetition frequency. In this paper, we develop utilities to systematically and efficiently assess the contributions of these parameters in relation to the limits, following directly from the 2014 American National Standards Institute (ANSI). We also provide an array of stimulus protocols that fall within the bounds of both safety and effectiveness. Additional verification of safety is provided with a case study in rats using one of these protocols. PMID:26882975

Non-Instrumental Movement Inhibition (NIMI) Differentially Suppresses Head and Thigh Movements during Screenic Engagement: Dependence on Interaction

PubMed Central

Witchel, Harry J.; Santos, Carlos P.; Ackah, James K.; Westling, Carina E. I.; Chockalingam, Nachiappan

2016-01-01

Background: Estimating engagement levels from postural micromovements has been summarized by some researchers as: increased proximity to the screen is a marker for engagement, while increased postural movement is a signal for disengagement or negative affect. However, these findings are inconclusive: the movement hypothesis challenges other findings of dyadic interaction in humans, and experiments on the positional hypothesis diverge from it. Hypotheses: (1) Under controlled conditions, adding a relevant visual stimulus to an auditory stimulus will preferentially result in Non-Instrumental Movement Inhibition (NIMI) of the head. (2) When instrumental movements are eliminated and computer-interaction rate is held constant, for two identically-structured stimuli, cognitive engagement (i.e., interest) will result in measurable NIMI of the body generally. Methods: Twenty-seven healthy participants were seated in front of a computer monitor and speakers. Discrete 3-min stimuli were presented with interactions mediated via a handheld trackball without any keyboard, to minimize instrumental movements of the participant's body. Music videos and audio-only music were used to test hypothesis (1). Time-sensitive, highly interactive stimuli were used to test hypothesis (2). Subjective responses were assessed via visual analog scales. The computer users' movements were quantified using video motion tracking from the lateral aspect. Repeated measures ANOVAs with Tukey post hoc comparisons were performed. Results: For two equivalently-engaging music videos, eliminating the visual content elicited significantly increased non-instrumental movements of the head (while also decreasing subjective engagement); a highly engaging user-selected piece of favorite music led to further increased non-instrumental movement. For two comparable reading tasks, the more engaging reading significantly inhibited (42%) movement of the head and thigh; however, when a highly engaging video game was compared to the boring reading, even though the reading task and the game had similar levels of interaction (trackball clicks), only thigh movement was significantly inhibited, not head movement. Conclusions: NIMI can be elicited by adding a relevant visual accompaniment to an audio-only stimulus or by making a stimulus cognitively engaging. However, these results presume that all other factors are held constant, because total movement rates can be affected by cognitive engagement, instrumental movements, visual requirements, and the time-sensitivity of the stimulus. PMID:26941666

Non-Instrumental Movement Inhibition (NIMI) Differentially Suppresses Head and Thigh Movements during Screenic Engagement: Dependence on Interaction.

PubMed

Witchel, Harry J; Santos, Carlos P; Ackah, James K; Westling, Carina E I; Chockalingam, Nachiappan

2016-01-01

Estimating engagement levels from postural micromovements has been summarized by some researchers as: increased proximity to the screen is a marker for engagement, while increased postural movement is a signal for disengagement or negative affect. However, these findings are inconclusive: the movement hypothesis challenges other findings of dyadic interaction in humans, and experiments on the positional hypothesis diverge from it. (1) Under controlled conditions, adding a relevant visual stimulus to an auditory stimulus will preferentially result in Non-Instrumental Movement Inhibition (NIMI) of the head. (2) When instrumental movements are eliminated and computer-interaction rate is held constant, for two identically-structured stimuli, cognitive engagement (i.e., interest) will result in measurable NIMI of the body generally. Twenty-seven healthy participants were seated in front of a computer monitor and speakers. Discrete 3-min stimuli were presented with interactions mediated via a handheld trackball without any keyboard, to minimize instrumental movements of the participant's body. Music videos and audio-only music were used to test hypothesis (1). Time-sensitive, highly interactive stimuli were used to test hypothesis (2). Subjective responses were assessed via visual analog scales. The computer users' movements were quantified using video motion tracking from the lateral aspect. Repeated measures ANOVAs with Tukey post hoc comparisons were performed. For two equivalently-engaging music videos, eliminating the visual content elicited significantly increased non-instrumental movements of the head (while also decreasing subjective engagement); a highly engaging user-selected piece of favorite music led to further increased non-instrumental movement. For two comparable reading tasks, the more engaging reading significantly inhibited (42%) movement of the head and thigh; however, when a highly engaging video game was compared to the boring reading, even though the reading task and the game had similar levels of interaction (trackball clicks), only thigh movement was significantly inhibited, not head movement. NIMI can be elicited by adding a relevant visual accompaniment to an audio-only stimulus or by making a stimulus cognitively engaging. However, these results presume that all other factors are held constant, because total movement rates can be affected by cognitive engagement, instrumental movements, visual requirements, and the time-sensitivity of the stimulus.

Rethinking human visual attention: spatial cueing effects and optimality of decisions by honeybees, monkeys and humans.

PubMed

Eckstein, Miguel P; Mack, Stephen C; Liston, Dorion B; Bogush, Lisa; Menzel, Randolf; Krauzlis, Richard J

2013-06-07

Visual attention is commonly studied by using visuo-spatial cues indicating probable locations of a target and assessing the effect of the validity of the cue on perceptual performance and its neural correlates. Here, we adapt a cueing task to measure spatial cueing effects on the decisions of honeybees and compare their behavior to that of humans and monkeys in a similarly structured two-alternative forced-choice perceptual task. Unlike the typical cueing paradigm in which the stimulus strength remains unchanged within a block of trials, for the monkey and human studies we randomized the contrast of the signal to simulate more real world conditions in which the organism is uncertain about the strength of the signal. A Bayesian ideal observer that weights sensory evidence from cued and uncued locations based on the cue validity to maximize overall performance is used as a benchmark of comparison against the three animals and other suboptimal models: probability matching, ignore the cue, always follow the cue, and an additive bias/single decision threshold model. We find that the cueing effect is pervasive across all three species but is smaller in size than that shown by the Bayesian ideal observer. Humans show a larger cueing effect than monkeys and bees show the smallest effect. The cueing effect and overall performance of the honeybees allows rejection of the models in which the bees are ignoring the cue, following the cue and disregarding stimuli to be discriminated, or adopting a probability matching strategy. Stimulus strength uncertainty also reduces the theoretically predicted variation in cueing effect with stimulus strength of an optimal Bayesian observer and diminishes the size of the cueing effect when stimulus strength is low. A more biologically plausible model that includes an additive bias to the sensory response from the cued location, although not mathematically equivalent to the optimal observer for the case stimulus strength uncertainty, can approximate the benefits of the more computationally complex optimal Bayesian model. We discuss the implications of our findings on the field's common conceptualization of covert visual attention in the cueing task and what aspects, if any, might be unique to humans. Copyright © 2013 Elsevier Ltd. All rights reserved.

Interoceptive conditioning with the nicotine stimulus: extinction learning as a method for assessing stimulus similarity across doses.

PubMed

Polewan, Robert J; Savala, Stephanie A; Bevins, Rick A

2013-02-01

Interoceptive conditioning involving the nicotine stimulus likely contributes to chronic tobacco use. To better understand the nature of this interoceptive conditioning, we compared generalization during repeated extinction with generalization in a 'transfer of extinction' test using a wide range of test doses. Rats were first trained in the discriminated goal-tracking task in which nicotine (0.2 or 0.4 mg/kg), but not saline, was paired with repeated intermittent access to sucrose. Across sessions, nicotine acquired control of approach behavior directed at the location of previous sucrose deliveries. Extinction followed with eight 20-min sessions without sucrose access; extinction doses of nicotine ranged from 0.05 to 0.6 mg/kg. In rats trained with 0.4 mg/kg, the 0.1, 0.2, and 0.6 mg/kg doses evoked comparable responding across extinction sessions; substitution was only partial at 0.05 and 0.075 mg/kg (i.e. above saline controls, but less than the training dose). With the 0.2 mg/kg training dose, complete generalization was seen only at the 0.1 and 0.4 mg/kg doses. After extinction, rats were given a transfer test with their training dose. Rats trained with 0.4 mg/kg showed full transfer of extinction learning with 0.1, 0.2, and 0.6 mg/kg (i.e. responding comparable with extinction with the training dose). Partial transfer was observed at 0.075 mg/kg. With the 0.2 mg/kg nicotine dose, only 0.4 mg/kg fully generalized; 0.075, 0.1, and 0.6 mg/kg showed partial transfer. Extinction with 0.05 mg/kg dose did not show transfer to either training dose. These findings indicated that conclusions regarding stimulus similarity across nicotine doses can vary with testing protocol.

Reducing radiation dose to the female breast during CT coronary angiography: A simulation study comparing breast shielding, angular tube current modulation, reduced kV, and partial angle protocols using an unknown-location signal-detectability metric

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rupcich, Franco; Gilat Schmidt, Taly; Badal, Andreu

2013-08-15

Purpose: The authors compared the performance of five protocols intended to reduce dose to the breast during computed tomography (CT) coronary angiography scans using a model observer unknown-location signal-detectability metric.Methods: The authors simulated CT images of an anthropomorphic female thorax phantom for a 120 kV reference protocol and five “dose reduction” protocols intended to reduce dose to the breast: 120 kV partial angle (posteriorly centered), 120 kV tube-current modulated (TCM), 120 kV with shielded breasts, 80 kV, and 80 kV partial angle (posteriorly centered). Two image quality tasks were investigated: the detection and localization of 4-mm, 3.25 mg/ml and 1-mm,more » 6.0 mg/ml iodine contrast signals randomly located in the heart region. For each protocol, the authors plotted the signal detectability, as quantified by the area under the exponentially transformed free response characteristic curve estimator (A-caret{sub FE}), as well as noise and contrast-to-noise ratio (CNR) versus breast and lung dose. In addition, the authors quantified each protocol's dose performance as the percent difference in dose relative to the reference protocol achieved while maintaining equivalent A-caret{sub FE}.Results: For the 4-mm signal-size task, the 80 kV full scan and 80 kV partial angle protocols decreased dose to the breast (80.5% and 85.3%, respectively) and lung (80.5% and 76.7%, respectively) with A-caret{sub FE} = 0.96, but also resulted in an approximate three-fold increase in image noise. The 120 kV partial protocol reduced dose to the breast (17.6%) at the expense of increased lung dose (25.3%). The TCM algorithm decreased dose to the breast (6.0%) and lung (10.4%). Breast shielding increased breast dose (67.8%) and lung dose (103.4%). The 80 kV and 80 kV partial protocols demonstrated greater dose reductions for the 4-mm task than for the 1-mm task, and the shielded protocol showed a larger increase in dose for the 4-mm task than for the 1-mm task. In general, the CNR curves indicate a similar relative ranking of protocol performance as the corresponding A-caret{sub FE} curves, however, the CNR metric overestimated the performance of the shielded protocol for both tasks, leading to corresponding underestimates in the relative dose increases compared to those obtained when using the A-caret{sub FE} metric.Conclusions: The 80 kV and 80 kV partial angle protocols demonstrated the greatest reduction to breast and lung dose, however, the subsequent increase in image noise may be deemed clinically unacceptable. Tube output for these protocols can be adjusted to achieve a more desirable noise level with lesser breast dose savings. Breast shielding increased breast and lung dose when maintaining equivalent A-caret{sub FE}. The results demonstrated that comparisons of dose performance depend on both the image quality metric and the specific task, and that CNR may not be a reliable metric of signal detectability.« less

Perceptual advantage for category-relevant perceptual dimensions: the case of shape and motion.

PubMed

Folstein, Jonathan R; Palmeri, Thomas J; Gauthier, Isabel

2014-01-01

Category learning facilitates perception along relevant stimulus dimensions, even when tested in a discrimination task that does not require categorization. While this general phenomenon has been demonstrated previously, perceptual facilitation along dimensions has been documented by measuring different specific phenomena in different studies using different kinds of objects. Across several object domains, there is support for acquired distinctiveness, the stretching of a perceptual dimension relevant to learned categories. Studies using faces and studies using simple separable visual dimensions have also found evidence of acquired equivalence, the shrinking of a perceptual dimension irrelevant to learned categories, and categorical perception, the local stretching across the category boundary. These later two effects are rarely observed with complex non-face objects. Failures to find these effects with complex non-face objects may have been because the dimensions tested previously were perceptually integrated. Here we tested effects of category learning with non-face objects categorized along dimensions that have been found to be processed by different areas of the brain, shape and motion. While we replicated acquired distinctiveness, we found no evidence for acquired equivalence or categorical perception.

Facile Reductive Silylation of UO22+ to Uranium(IV) Chloride.

PubMed

Kiernicki, John J; Zeller, Matthias; Bart, Suzanne C

2017-01-19

General reductive silylation of the UO 2 2+ cation occurs readily in a one-pot, two-step stoichiometric reaction at room temperature to form uranium(IV) siloxides. Addition of two equivalents of an alkylating reagent to UO 2 X 2 (L) 2 (X=Cl, Br, I, OTf; L=triphenylphosphine oxide, 2,2'-bipyridyl) followed by two equivalents of a silyl (pseudo)halide, R 3 Si-X (R=aryl, alkyl, H; X=Cl, Br, I, OTf, SPh), cleanly affords (R 3 SiO) 2 UX 2 (L) 2 in high yields. Support is included for the key step in the process, reduction of U VI to U V . This procedure is applicable to a wide range of commercially available uranyl salts, silyl halides, and alkylating reagents. Under this protocol, one equivalent of SiCl 4 or two equivalents of Me 2 SiCl 2 results in direct conversion of the uranyl to uranium(IV) tetrachloride. Full spectroscopic and structural characterization of the siloxide products is reported. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Teaching topography-based and selection-based verbal behavior to developmentally disabled individuals: Some considerations

PubMed Central

Shafer, Esther

1993-01-01

Augmentative and alternative communication systems are widely recommended for nonvocal developmentally disabled individuals, with selection-based systems becoming increasingly popular. However, theoretical and experimental evidence suggests that topography-based communication systems are easier to learn. This paper discusses research relevant to the ease of acquisition of topography-based and selection-based systems. Additionally, current practices for choosing and designing communication systems are reviewed in order to investigate the extent to which links have been made with available theoretical and experimental knowledge. A stimulus equivalence model is proposed as a clearer direction for practitioners to follow when planning a communication training program. Suggestions for future research are also offered. PMID:22477085

Continuous-variable quantum key distribution based on a plug-and-play dual-phase-modulated coherent-states protocol

NASA Astrophysics Data System (ADS)

Huang, Duan; Huang, Peng; Wang, Tao; Li, Huasheng; Zhou, Yingming; Zeng, Guihua

2016-09-01

We propose and experimentally demonstrate a continuous-variable quantum key distribution (CV-QKD) protocol using dual-phase-modulated coherent states. We show that the modulation scheme of our protocol works equivalently to that of the Gaussian-modulated coherent-states (GMCS) protocol, but shows better experimental feasibility in the plug-and-play configuration. Besides, it waives the necessity of propagation of a local oscillator (LO) between legitimate users and generates a real local LO for quantum measurement. Our protocol is proposed independent of the one-way GMCS QKD without sending a LO [Opt. Lett. 40, 3695 (2015), 10.1364/OL.40.003695; Phys. Rev. X 5, 041009 (2015), 10.1103/PhysRevX.5.041009; Phys. Rev. X 5, 041010 (2015), 10.1103/PhysRevX.5.041010]. In those recent works, the system stability will suffer the impact of polarization drifts induced by environmental perturbations, and two independent frequency-locked laser sources are necessary to achieve reliable coherent detection. In the proposed protocol, these previous problems can be resolved. We derive the security bounds for our protocol against collective attacks, and we also perform a proof-of-principle experiment to confirm the utility of our proposal in real-life applications. Such an efficient scheme provides a way of removing the security loopholes associated with the transmitting LO, which have been a notoriously hard problem in continuous-variable quantum communication.

Radiation-induced changes in gustatory function comparison of effects of neutron and photon irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mossman, K.L.; Chencharick, J.D.; Scheer, A.C.

1979-04-01

Changes in gustatory function were measured in 51 patients with various forms of cancer who received radiation to the head and neck region. Forty patients (group I) were treated with conventional photon radiation (e.g. 66 Gy/7 weeks), and 11 patients (group II) were treated with cyclotron produced fast neutrons (e.g. 22 Gy/7 weeks). Taste acuity was measured for four taste qualities (salt, sweet, sour, and bitter) by a forced choice-three stimulus drop technique which measured detection and recognition thresholds and by a forced scaling technique which measured taste intensity responsiveness. Subjective complaints of anorexia, dysgeusia, taste loss, and xerostomia weremore » also recorded. Patients were studied before, during and up to two months after therapy. Prior to therapy, detection and recognition thresholds, intensity responsiveness, and the frequency of subjective complaints in patients from groups I and II were statistically equivalent. During and up to 2 months after therapy, taste impairment and frequency of subjective complaints increased significantly in neutron and photon treated patients, but were statistically equivalent. Results of this study indicate that gustatory tissue response as measured by taste detection and recognition and intensity responsiveness, and the frequency of subjective complaints related to taste are statistically equivalent in patients before, during, or up 2 months after they were given either neutron or photon radiation for tumors of the head and neck.« less

Use of a Novel Cell Adhesion Method and Digital Measurement to Show Stimulus-dependent Variation in Somatic and Oral Ciliary Beat Frequency in Paramecium

PubMed Central

Bell, Wade E.; Hallworth, Richard; Wyatt, Todd A.; Sisson, Joseph H.

2015-01-01

When Paramecium encounters positive stimuli, the membrane hyperpolarizes and ciliary beat frequency increases. We adapted an established immobilization protocol using a biological adhesive and a novel digital analysis system to quantify beat frequency in immobilized Paramecium. Cells showed low mortality and demonstrated beat frequencies consistent with previous studies. Chemoattractant molecules, reduction in external potassium, and posterior stimulation all increased somatic beat frequency. In all cases, the oral groove cilia maintained a higher beat frequency than mid-body cilia, but only oral cilia from cells stimulated with chemoattactants showed an increase from basal levels. PMID:25066640

An unconditioned stimulus retrieval extinction procedure to prevent the return of fear memory.

PubMed

Liu, Jianfeng; Zhao, Liyan; Xue, Yanxue; Shi, Jie; Suo, Lin; Luo, Yixiao; Chai, Baisheng; Yang, Chang; Fang, Qin; Zhang, Yan; Bao, Yanping; Pickens, Charles L; Lu, Lin

2014-12-01

Conditioned fear memories can be updated by extinction during reconsolidation, and this effect is specific to the reactivated conditioned stimulus (CS). However, a traumatic event can be associated with several cues, and each cue can potentially trigger recollection of the event. We introduced a technique to target all diverse cues associated with an aversive event that causes fear. In human experiments, 161 subjects underwent modified fear conditioning, in which they were exposed to an unconditioned stimulus (US) or unreinforced CS to reactivate the memory and then underwent extinction, spontaneous recovery, and reinstatement. In animal experiments, 343 rats underwent contextual fear conditioning under a similar protocol as that used in the human experiments. We also explored the molecular alterations after US reactivation in rats. Presentation of a lower intensity US before extinction disrupted the associations between the different CS and reactivated US in both humans and rats. This effect persisted for at least 6 months in humans and was selective to the reactivated US. This procedure was also effective for remote memories in both humans and rats. Compared with the CS, the US induced stronger endocytosis of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid glutamate receptors 1 and 2 and stronger activation of protein kinase A, p70S6 kinase, and cyclic adenosine monophosphate response element binding protein in the dorsal hippocampus in rats. These findings demonstrate that a modified US retrieval extinction strategy may have a potential impact on therapeutic approaches to prevent the return of fear. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Security Enhanced EMV-Based Mobile Payment Protocol

PubMed Central

2014-01-01

Near field communication has enabled customers to put their credit cards into a smartphone and use the phone for credit card transaction. But EMV contactless payment allows unauthorized readers to access credit cards. Besides, in offline transaction, a merchant's reader cannot verify whether a card has been revoked. Therefore, we propose an EMV-compatible payment protocol to mitigate the transaction risk. And our modifications to the EMV standard are transparent to merchants and users. We also encrypt the communications between a card and a reader to prevent eavesdropping on sensitive data. The protocol is able to resist impersonation attacks and to avoid the security threats in EMV. In offline transactions, our scheme requires a user to apply for a temporary offline certificate in advance. With the certificate, banks no longer need to lower customer's credits for risk control, and users can have online-equivalent credits in offline transactions. PMID:25302334

Security enhanced EMV-based mobile payment protocol.

PubMed

Yang, Ming-Hour

2014-01-01

Near field communication has enabled customers to put their credit cards into a smartphone and use the phone for credit card transaction. But EMV contactless payment allows unauthorized readers to access credit cards. Besides, in offline transaction, a merchant's reader cannot verify whether a card has been revoked. Therefore, we propose an EMV-compatible payment protocol to mitigate the transaction risk. And our modifications to the EMV standard are transparent to merchants and users. We also encrypt the communications between a card and a reader to prevent eavesdropping on sensitive data. The protocol is able to resist impersonation attacks and to avoid the security threats in EMV. In offline transactions, our scheme requires a user to apply for a temporary offline certificate in advance. With the certificate, banks no longer need to lower customer's credits for risk control, and users can have online-equivalent credits in offline transactions.

In vivo evaluation of the effect of stimulus distribution on FIR statistical efficiency in event-related fMRI

PubMed Central

Jansma, J Martijn; de Zwart, Jacco A; van Gelderen, Peter; Duyn, Jeff H; Drevets, Wayne C; Furey, Maura L

2013-01-01

Technical developments in MRI have improved signal to noise, allowing use of analysis methods such as Finite impulse response (FIR) of rapid event related functional MRI (er-fMRI). FIR is one of the most informative analysis methods as it determines onset and full shape of the hemodynamic response function (HRF) without any a-priori assumptions. FIR is however vulnerable to multicollinearity, which is directly related to the distribution of stimuli over time. Efficiency can be optimized by simplifying a design, and restricting stimuli distribution to specific sequences, while more design flexibility necessarily reduces efficiency. However, the actual effect of efficiency on fMRI results has never been tested in vivo. Thus, it is currently difficult to make an informed choice between protocol flexibility and statistical efficiency. The main goal of this study was to assign concrete fMRI signal to noise values to the abstract scale of FIR statistical efficiency. Ten subjects repeated a perception task with five random and m-sequence based protocol, with varying but, according to literature, acceptable levels of multicollinearity. Results indicated substantial differences in signal standard deviation, while the level was a function of multicollinearity. Experiment protocols varied up to 55.4% in standard deviation. Results confirm that quality of fMRI in an FIR analysis can significantly and substantially vary with statistical efficiency. Our in vivo measurements can be used to aid in making an informed decision between freedom in protocol design and statistical efficiency. PMID:23473798

Financial incentive does not affect P300 (in response to certain episodic and semantic probe stimuli) in the Complex Trial Protocol (CTP) version of the Concealed Information Test (CIT) in detection of malingering.

PubMed

Rosenfeld, J Peter; Labkovsky, Elena; Davydova, Elena; Ward, Anne; Rosenfeld, Lauren

2017-05-01

Previous research indicated that the skin conductance response of the autonomic nervous system in the Concealed Information Test (CIT) is typically increased in subjects who are financially and otherwise incentivized to defeat the CIT (the paradoxical "motivational impairment" effect). This is not the case for RT-based CITs, nor P300 tests based on the three-stimulus protocol for detection of cognitive malingering (although these are not the same as CITs). The present report is the first attempt to study the effect of financial motivation on the P300-based Complex Trial Protocol using both episodic and semantic memory probe and irrelevant stimuli. The Test of Memory Malingering (TOMM) was used to validate behavioral differences between the two groups we created by offering one (paid) group but not another (unpaid) group a financial reward for beating our tests. Group behavioral differences on the TOMM did confirm group manipulations. Probe-minus-irrelevant P300 differences did not differ between groups, although as previously, semantic memory-evoked P300s were larger than episodic memory-evoked P300s. © 2017 Society for Psychophysiological Research.

Auditory evoked potentials in the auditory system of a beluga whale Delphinapterus leucas to prolonged sound stimuli.

PubMed

Popov, Vladimir V; Sysueva, Evgenia V; Nechaev, Dmitry I; Rozhnov, Vyatcheslav V; Supin, Alexander Ya

2016-03-01

The effects of prolonged (up to 1500 s) sound stimuli (tone pip trains) on evoked potentials (the rate following response, RFR) were investigated in a beluga whale. The stimuli (rhythmic tone pips) were of frequencies of 45, 64, and 90 kHz at levels from 20 to 60 dB above threshold. Two experimental protocols were used: short- and long-duration. For the short-duration protocol, the stimuli were 500-ms-long pip trains that repeated at a rate of 0.4 trains/s. For the long-duration protocol, the stimuli were continuous pip successions lasting up to 1500 s. The RFR amplitude gradually decreased by three to seven times from 10 ms to 1500 s of stimulation. Decrease of response amplitude during stimulation was approximately proportional to initial (at the start of stimulation) response amplitude. Therefore, even for low stimulus level (down to 20 dB above the baseline threshold) the response was never suppressed completely. The RFR amplitude decay that occurred during stimulation could be satisfactorily approximated by a combination of two exponents with time constants of 30-80 ms and 3.1-17.6 s. The role of adaptation in the described effects and the impact of noise on the acoustic orientation of odontocetes are discussed.

A framework for the definition of standardized protocols for measuring upper-extremity kinematics.

PubMed

Kontaxis, A; Cutti, A G; Johnson, G R; Veeger, H E J

2009-03-01

Increasing interest in upper extremity biomechanics has led to closer investigations of both segment movements and detailed joint motion. Unfortunately, conceptual and practical differences in the motion analysis protocols used up to date reduce compatibility for post data and cross validation analysis and so weaken the body of knowledge. This difficulty highlights a need for standardised protocols, each addressing a set of questions of comparable content. The aim of this work is therefore to open a discussion and propose a flexible framework to support: (1) the definition of standardised protocols, (2) a standardised description of these protocols, and (3) the formulation of general recommendations. Proposal of a framework for the definition of standardized protocols. The framework is composed by two nested flowcharts. The first defines what a motion analysis protocol is by pointing out its role in a motion analysis study. The second flowchart describes the steps to build a protocol, which requires decisions on the joints or segments to be investigated and the description of their mechanical equivalent model, the definition of the anatomical or functional coordinate frames, the choice of marker or sensor configuration and the validity of their use, the definition of the activities to be measured and the refinements that can be applied to the final measurements. Finally, general recommendations are proposed for each of the steps based on the current literature, and open issues are highlighted for future investigation and standardisation. Standardisation of motion analysis protocols is urgent. The proposed framework can guide this process through the rationalisation of the approach.

Weapons and Materials Research Directorate (WMRD) Laboratory Demonstration Study

DTIC Science & Technology

2015-02-01

increases) • Miscellaneous (Protocol for determining GS equivalency and Special Act or Service awards) • Intern and Student Trainee Benchmarking The ARL...the burden, to Department of Defense, Washington Headquarters Services , Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson...change from the Civil Service General Schedule (GS) system were 1) enhanced hiring flexibilities, 2) broadbanding, 3) automated classification, 4

Speech evaluation after intravelar veloplasty. How to use Borel-Maisonny classification in the international literature?

PubMed

Kadlub, N; Chapuis Vandenbogaerde, C; Joly, A; Neiva, C; Vazquez, M-P; Picard, A

2018-04-01

Comparing functional outcomes after velar repair appeared to be difficult because of the absence of international standardized scale. Moreover most of the studies evaluating speech after cleft surgery present multiple biases. The aim of our study was to assess speech outcomes in a homogeneous group of patients, and to define an equivalence table between different speech scales. Patients with isolated cleft lip and palate (CLP), operated in our unit by the same senior surgeon were included. All patient were operated according to the same protocol (cheilo-rhinoplasty and intravelar veloplasty at 6 months, followed by a direct closure of the hard palate at 15 months). Speech evaluation was performed after 3 year-old and before the alveolar cleft repair. Borel-Maisonny scale and nasometry were used for speech evaluation. Twenty-four patients were included: 17 unilateral CLP and 7 bilateral CLP. According to the Borel-Maisonny classifications, 82.5% were ranged phonation 1, 1-2 or 2b. Nasometry were normal in almost 60% of cases. This study showed the efficiency of our protocol, and intravelar veloplasty. Moreover we proposed an equivalence table for speech evaluation scale. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Comparison of Clobetasol Propionate Generics Using Simplified in Vitro Bioequivalence Method for Topical Drug Products.

PubMed

Soares, Kelen Carine Costa; de Souza, Weidson Carlos; de Souza Texeira, Leonardo; da Cunha-Filho, Marcilio Sergio Soares; Gelfuso, Guilherme Martins; Gratieri, Tais

2017-11-20

The aim of this paper is to propose a simple in vitro skin penetration experiment in which the drug is extracted from the whole skin piece as a test valid for formulation screening and optimization during development process, equivalence assessment during quality control or post-approval after changes to the product. Twelve clobetasol propionate (CP) formulations (six creams and six ointments) from the local market were used as a model to challenge the proposed methodology in comparison to in vitro skin penetration following tape-stripping for drug extraction. To support the results, physicochemical tests for pH, viscosity, density and assay, as well as in vitro release were performed. Both protocols, extracting the drug from the skin using the tape-stripping technique or extracting from the full skin were capable of differentiating CP formulations. Only one formulation did not present statistical difference from the reference drug product in penetration tests and only other two oitments presented equivalent release to the reference. The proposed protocol is straightforward and reproducible. Results suggest the bioinequavalence of tested CP formulations reinforcing the necessity of such evaluations. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Motor excitability measurements: the influence of gender, body mass index, age and temperature in healthy controls.

PubMed

Casanova, I; Diaz, A; Pinto, S; de Carvalho, M

2014-04-01

The technique of threshold tracking to test axonal excitability gives information about nodal and internodal ion channel function. We aimed to investigate variability of the motor excitability measurements in healthy controls, taking into account age, gender, body mass index (BMI) and small changes in skin temperature. We examined the left median nerve of 47 healthy controls using the automated threshold-tacking program, QTRAC. Statistical multiple regression analysis was applied to test relationship between nerve excitability measurements and subject variables. Comparisons between genders did not find any significant difference (P>0.2 for all comparisons). Multiple regression analysis showed that motor amplitude decreases with age and temperature, stimulus-response slope decreases with age and BMI, and that accommodation half-time decrease with age and temperature. The changes related to demographic features on TRONDE protocol parameters are small and less important than in conventional nerve conduction studies. Nonetheless, our results underscore the relevance of careful temperature control, and indicate that interpretation of stimulus-response slope and accommodation half-time should take into account age and BMI. In contrast, gender is not of major relevance to axonal threshold findings in motor nerves. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

A functional magnetic resonance imaging assessment of small animals' phobia using virtual reality as a stimulus.

PubMed

Clemente, Miriam; Rey, Beatriz; Rodriguez-Pujadas, Aina; Breton-Lopez, Juani; Barros-Loscertales, Alfonso; Baños, Rosa M; Botella, Cristina; Alcañiz, Mariano; Avila, Cesar

2014-06-27

To date, still images or videos of real animals have been used in functional magnetic resonance imaging protocols to evaluate the brain activations associated with small animals' phobia. The objective of our study was to evaluate the brain activations associated with small animals' phobia through the use of virtual environments. This context will have the added benefit of allowing the subject to move and interact with the environment, giving the subject the illusion of being there. We have analyzed the brain activation in a group of phobic people while they navigated in a virtual environment that included the small animals that were the object of their phobia. We have found brain activation mainly in the left occipital inferior lobe (P<.05 corrected, cluster size=36), related to the enhanced visual attention to the phobic stimuli; and in the superior frontal gyrus (P<.005 uncorrected, cluster size=13), which is an area that has been previously related to the feeling of self-awareness. In our opinion, these results demonstrate that virtual stimulus can enhance brain activations consistent with previous studies with still images, but in an environment closer to the real situation the subject would face in their daily lives.

Multimodal gain control at the hippocampal Schaffer collateral-CA1 synapse.

PubMed

Lange-Asschenfeldt, Christian; Schipke, Carola G; Riepe, Matthias W

2007-04-06

Information processing at central nervous system synapses is shaped by long-lasting modifications, such as long-term potentiation and short-lived and putatively synapse-specific modifications by various forms of short-term plasticity, such as facilitation, potentiation, and depression. Using an extracellular paired-pulse facilitation (PPF) protocol at the Schaffer collateral-CA1 (SC) connection in acute hippocampal slices in mice, we extend previous reports of optimal signal gain at intermediate interpulse intervals obtained at single SC synapses to the network level. Moreover, maximum signal gain changed when the input intensity was altered. We found further that facilitation decreased with increasing stimulus amplitude and duration in an exact exponential fashion when varied at a fixed interpulse interval. Variation of these intensity parameters accounted for significant changes in PPF adding a spatial dimension to time-based synaptic filter characteristics. Thus, this synapse functions as an amplitude window discriminator with a low-level aperture in combination with a band-pass frequency filter. By providing mathematical functions for the characteristic presynaptic parameters frequency, stimulus amplitude, and pulse duration at the network level our results lay ground for future studies on pharmacologically, genetically, or otherwise altered animal models.

Impaired preparatory re-mapping of stimulus-response associations and rule-implementation in schizophrenic patients--the role for differences in early processing.

PubMed

Finke, Mareike; Barceló, Francisco; Garolera, Maite; Cortiñas, Miriam; Garrido, Gemma; Pajares, Marta; Escera, Carles

2011-07-01

An accurate representation of task-set information is needed for successful goal directed behavior. Recent studies point to disturbances in the early processing stages as plausible causes for task-switching deficits in schizophrenia. A task-cueing protocol was administered to a group of schizophrenic patients and compared with a sample of age-matched healthy controls. Patients responded slower and less accurate compared with controls in all conditions. The concurrent recording of event-related brain potentials to contextual cues and target events revealed abnormalities in the early processing of both cue-locked and target-locked N1 potentials. Abnormally enhanced target-locked P2 amplitudes were observed in schizophrenic patients for task-switch trials only, suggesting disrupted stimulus evaluation and memory retrieval processes. The endogenous P3 potentials discriminated between task conditions but without further differences between groups. These results suggest that the observed impairments in task-switching behavior were not specifically related to anticipatory set-shifting, but derived from a deficit in the implementation of task-set representations at target onset in the presence of irrelevant and conflicting information. Copyright © 2011 Elsevier B.V. All rights reserved.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction.

PubMed

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load-and other aspects of task difficulty-increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information-which decreases distractibility-as a side effect of the increased activity in a focused-attention network.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction

PubMed Central

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load—and other aspects of task difficulty—increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information—which decreases distractibility—as a side effect of the increased activity in a focused-attention network. PMID:27242485

Effect of intermittent standing and walking on physiological changes induced by head-down bed rest

NASA Technical Reports Server (NTRS)

Vernikos, J.; Ludwig, D. A.; Ertl, A. C.; Wade, C. E.; Keil, L.; OHara, D.

1994-01-01

Continuous exposure to gravity may not be necessary to prevent compromised physiological function resulting from exposure to microgravity. However, minimum gravity (G) exposure requirements, effectiveness of passive Gz versus activity in a G field, and optimal G stimulus amplitude, duration, and frequency are unknown. To partially address these questions, a 4-day, 6 degree head-down bed rest (HDBR) study (one ambulatory control day, 4 full HDBR days, one recovery day) was conducted. Nine males, 30-50 yr, were subjected to four different +1 Gz (head-foot) exposure protocols (periodic standing or controlled walking for 2 or 4 h/day in 15 min doses), plus a continuous HDBR (0 Gz) control. Standing 4 h completely prevented and standing 2 h partially prevented post-HDBR orthostatic intolerance. Both walking conditions (2 h and 4 h) attenuated the decrease in peak VO2 and prevented the increased urinary Ca2+ excretion associated with HDBR. Both 4 h conditions (standing and walking) attenuated plasma volume loss during HDBR. It was concluded that various physiological systems benefit differentially from passive +1 Gz or activity in +1 Gz and the duration (2 h vs. 4 h) of the stimulus may be an important moderating factor.

Regulation of muscle sympathetic nerve activity after bed rest deconditioning

NASA Technical Reports Server (NTRS)

Pawelczyk, J. A.; Zuckerman, J. H.; Blomqvist, C. G.; Levine, B. D.

2001-01-01

Cardiovascular deconditioning reduces orthostatic tolerance. To determine whether changes in autonomic function might produce this effect, we developed stimulus-response curves relating limb vascular resistance, muscle sympathetic nerve activity (MSNA), and pulmonary capillary wedge pressure (PCWP) with seven subjects before and after 18 days of -6 degrees head-down bed rest. Both lower body negative pressure (LBNP; -15 and -30 mmHg) and rapid saline infusion (15 and 30 ml/kg body wt) were used to produce a wide variation in PCWP. Orthostatic tolerance was assessed with graded LBNP to presyncope. Bed rest reduced LBNP tolerance from 23.9 +/- 2.1 to 21.2 +/- 1.5 min, respectively (means +/- SE, P = 0.02). The MSNA-PCWP relationship was unchanged after bed rest, though at any stage of the LBNP protocol PCWP was lower, and MSNA was greater. Thus bed rest deconditioning produced hypovolemia, causing a shift in operating point on the stimulus-response curve. The relationship between limb vascular resistance and MSNA was not significantly altered after bed rest. We conclude that bed rest deconditioning does not alter reflex control of MSNA, but may produce orthostatic intolerance through a combination of hypovolemia and cardiac atrophy.

Psychophysical correspondence between vibrotactile intensity and intracortical microstimulation for tactile neuroprostheses in rats

NASA Astrophysics Data System (ADS)

Devecioğlu, İsmail; Güçlü, Burak

2017-02-01

Objective. Recent studies showed that intracortical microstimulation (ICMS) generates artificial sensations which can be utilized as somatosensory feedback in cortical neuroprostheses. To mimic the natural psychophysical response, ICMS parameters are modulated according to psychometric equivalence functions (PEFs). PEFs match the intensity levels of ICMS and mechanical stimuli, which elicit equal detection probabilities, but they typically do not include the frequency as a control variable. We aimed to establish frequency-dependent PEFs for vibrotactile stimulation of the glabrous skin and ICMS in the primary somatosensory cortex of awake freely behaving rats. Approach. We collected psychometric data for vibrotactile and ICMS detection at three stimulation frequencies (40, 60 and 80 Hz). The psychometric data were fitted with a model equation of two independent variables (stimulus intensity and frequency) and four subject-dependent parameters. For each rat, we constructed a separate PEF which was used to estimate the ICMS current amplitude for a given displacement amplitude and frequency. The ICMS frequency was set equal to the vibrotactile frequency. We validated the PEFs in a modified task which included randomly selected probe trials presented either with a vibrotactile or an ICMS stimulus, and also at frequencies and intensity levels not tested before. Main results. The PEFs were generally successful in estimating the ICMS current intensities (no significant differences between vibrotactile and ICMS trials in Kolmogorov-Smirnov tests). Specifically, hit rates from both trial conditions were significantly correlated in 86% of the cases, and 52% of all data had perfect match in linear regression. Significance. The psychometric correspondence model presented in this study was constructed based on surface functions which define psychophysical detection probability as a function of stimulus intensity and frequency. Therefore, it may be used for the real-time modulation of the frequency and intensity of ICMS pulses in somatosensory neuroprostheses.

Psychophysical correspondence between vibrotactile intensity and intracortical microstimulation for tactile neuroprostheses in rats.

PubMed

Devecioğlu, İsmail; Güçlü, Burak

2017-02-01

Recent studies showed that intracortical microstimulation (ICMS) generates artificial sensations which can be utilized as somatosensory feedback in cortical neuroprostheses. To mimic the natural psychophysical response, ICMS parameters are modulated according to psychometric equivalence functions (PEFs). PEFs match the intensity levels of ICMS and mechanical stimuli, which elicit equal detection probabilities, but they typically do not include the frequency as a control variable. We aimed to establish frequency-dependent PEFs for vibrotactile stimulation of the glabrous skin and ICMS in the primary somatosensory cortex of awake freely behaving rats. We collected psychometric data for vibrotactile and ICMS detection at three stimulation frequencies (40, 60 and 80 Hz). The psychometric data were fitted with a model equation of two independent variables (stimulus intensity and frequency) and four subject-dependent parameters. For each rat, we constructed a separate PEF which was used to estimate the ICMS current amplitude for a given displacement amplitude and frequency. The ICMS frequency was set equal to the vibrotactile frequency. We validated the PEFs in a modified task which included randomly selected probe trials presented either with a vibrotactile or an ICMS stimulus, and also at frequencies and intensity levels not tested before. The PEFs were generally successful in estimating the ICMS current intensities (no significant differences between vibrotactile and ICMS trials in Kolmogorov-Smirnov tests). Specifically, hit rates from both trial conditions were significantly correlated in 86% of the cases, and 52% of all data had perfect match in linear regression. The psychometric correspondence model presented in this study was constructed based on surface functions which define psychophysical detection probability as a function of stimulus intensity and frequency. Therefore, it may be used for the real-time modulation of the frequency and intensity of ICMS pulses in somatosensory neuroprostheses.

Multifactorial Experimental Design to Optimize the Anti-Inflammatory and Proangiogenic Potential of Mesenchymal Stem Cell Spheroids.

PubMed

Murphy, Kaitlin C; Whitehead, Jacklyn; Falahee, Patrick C; Zhou, Dejie; Simon, Scott I; Leach, J Kent

2017-06-01

Mesenchymal stem cell therapies promote wound healing by manipulating the local environment to enhance the function of host cells. Aggregation of mesenchymal stem cells (MSCs) into three-dimensional spheroids increases cell survival and augments their anti-inflammatory and proangiogenic potential, yet there is no consensus on the preferred conditions for maximizing spheroid function in this application. The objective of this study was to optimize conditions for forming MSC spheroids that simultaneously enhance their anti-inflammatory and proangiogenic nature. We applied a design of experiments (DOE) approach to determine the interaction between three input variables (number of cells per spheroid, oxygen tension, and inflammatory stimulus) on MSC spheroids by quantifying secretion of prostaglandin E 2 (PGE 2 ) and vascular endothelial growth factor (VEGF), two potent molecules in the MSC secretome. DOE results revealed that MSC spheroids formed with 40,000 cells per spheroid in 1% oxygen with an inflammatory stimulus (Spheroid 1) would exhibit enhanced PGE 2 and VEGF production versus those formed with 10,000 cells per spheroid in 21% oxygen with no inflammatory stimulus (Spheroid 2). Compared to Spheroid 2, Spheroid 1 produced fivefold more PGE 2 and fourfold more VEGF, providing the opportunity to simultaneously upregulate the secretion of these factors from the same spheroid. The spheroids induced macrophage polarization, sprout formation with endothelial cells, and keratinocyte migration in a human skin equivalent model-demonstrating efficacy on three key cell types that are dysfunctional in chronic non-healing wounds. We conclude that DOE-based analysis effectively identifies optimal culture conditions to enhance the anti-inflammatory and proangiogenic potential of MSC spheroids. Stem Cells 2017;35:1493-1504. © 2017 AlphaMed Press.

Increased reaction time variability in attention-deficit hyperactivity disorder as a response-related phenomenon: evidence from single-trial event-related potentials.

PubMed

Saville, Christopher W N; Feige, Bernd; Kluckert, Christian; Bender, Stephan; Biscaldi, Monica; Berger, Andrea; Fleischhaker, Christian; Henighausen, Klaus; Klein, Christoph

2015-07-01

Increased intra-subject variability (ISV) in reaction times (RTs) is a promising endophenotype for attention-deficit hyperactivity disorder (ADHD) and among the most robust hallmarks of the disorder. ISV has been assumed to represent an attentional deficit, either reflecting lapses in attention or increased neural noise. Here, we use an innovative single-trial event-related potential approach to assess whether the increased ISV associated with ADHD is indeed attributable to attention, or whether it is related to response-related processing. We measured electroencephalographic responses to working memory oddball tasks in patients with ADHD (N = 20, aged 11.3 ± 1.1) and healthy controls (N = 25, aged 11.7 ± 1.1), and analysed these data with a recently developed method of single-trial event-related potential analysis. Estimates of component latency variability were computed for the stimulus-locked and response-locked forms of the P3b and the lateralised readiness potential (LRP). ADHD patients showed significantly increased ISV in behavioural ISV. This increased ISV was paralleled by an increase in variability in response-locked event-related potential latencies, while variability in stimulus-locked latencies was equivalent between groups. This result held across the P3b and LRP. Latency of all components predicted RTs on a single-trial basis, confirming that all were relevant for speed of processing. These data suggest that the increased ISV found in ADHD could be associated with response-end, rather than stimulus-end processes, in contrast to prevailing conceptions about the endophenotype. This mental chronometric approach may also be useful for exploring whether the existing lack of specificity of ISV to particular psychiatric conditions can be improved upon. © 2014 Association for Child and Adolescent Mental Health.

Monitoring of hemodynamic changes induced in the healthy breast through inspired gas stimuli with MR-guided diffuse optical imaging

PubMed Central

Carpenter, C. M.; Rakow-Penner, R.; Jiang, S.; Pogue, B. W.; Glover, G. H.; Paulsen, K. D.

2010-01-01

Purpose: The modulation of tissue hemodynamics has important clinical value in medicine for both tumor diagnosis and therapy. As an oncological tool, increasing tissue oxygenation via modulation of inspired gas has been proposed as a method to improve cancer therapy and determine radiation sensitivity. As a radiological tool, inducing changes in tissue total hemoglobin may provide a means to detect and characterize malignant tumors by providing information about tissue vascular function. The ability to change and measure tissue hemoglobin and oxygenation concentrations in the healthy breast during administration of three different types of modulated gas stimuli (oxygen∕carbogen, air∕carbogen, and air∕oxygen) was investigated. Methods: Subjects breathed combinations of gases which were modulated in time. MR-guided diffuse optical tomography measured total hemoglobin and oxygen saturation in the breast every 30 s during the 16 min breathing stimulus. Metrics of maximum correlation and phase lag were calculated by cross correlating the measured hemodynamics with the stimulus. These results were compared to an air∕air control to determine the hemodynamic changes compared to the baseline physiology. Results: This study demonstrated that a gas stimulus consisting of alternating oxygen∕carbogen induced the largest and most robust hemodynamic response in healthy breast parenchyma relative to the changes that occurred during the breathing of room air. This stimulus caused increases in total hemoglobin and oxygen saturation during the carbogen phase of gas inhalation, and decreases during the oxygen phase. These findings are consistent with the theory that oxygen acts as a vasoconstrictor, while carbogen acts as a vasodilator. However, difficulties in inducing a consistent change in tissue hemoglobin and oxygenation were observed because of variability in intersubject physiology, especially during the air∕oxygen or air∕carbogen modulated breathing protocols. Conclusions: MR-guided diffuse optical imaging is a unique tool that can measure tissue hemodynamics in the breast during modulated breathing. This technique may have utility in determining the therapeutic potential of pretreatment tissue oxygenation or in investigating vascular function. Future gas modulation studies in the breast should use a combination of oxygen and carbogen as the functional stimulus. Additionally, control measures of subject physiology during air breathing are critical for robust measurements. PMID:20443485

A neural model of hippocampal-striatal interactions in associative learning and transfer generalization in various neurological and psychiatric patients

PubMed Central

Moustafa, Ahmed A.; Keri, Szabolcs; Herzallah, Mohammad M.; Myers, Catherine E.; Gluck, Mark A.

2010-01-01

Building on our previous neurocomputational models of basal ganglia and hippocampal-region function (and their modulation by dopamine and acetylcholine, respectively), we show here how an integration of these models can inform our understanding of the interaction between the basal ganglia and hippocampal region in associative learning and transfer generalization across various patient populations. As a common test bed for exploring interactions between these brain regions and neuromodulators, we focus on the acquired equivalence task, an associative learning paradigm in which stimuli that have been associated with the same outcome acquire a functional similarity such that subsequent generalization between these stimuli increases. This task has been used to test cognitive dysfunction in various patient populations with damages to the hippocampal region and basal ganglia, including studies of patients with Parkinson’s disease (PD), schizophrenia, basal forebrain amnesia, and hippocampal atrophy. Simulation results show that damage to the hippocampal region—as in patients with hippocampal atrophy (HA), hypoxia, mild Alzheimer’s (AD), or schizophrenia—leads to intact associative learning but impaired transfer generalization performance. Moreover, the model demonstrates how PD and anterior communicating artery (ACoA) aneurysm—two very different brain disorders that affect different neural mechanisms—can have similar effects on acquired equivalence performance. In particular, the model shows that simulating a loss of dopamine function in the basal ganglia module (as in PD) leads to slow acquisition learning but intact transfer generalization. Similarly, the model shows that simulating the loss of acetylcholine in the hippocampal region (as in ACoA aneurysm) also results in slower acquisition learning. We argue from this that changes in associative learning of stimulus-action pathways (in the basal ganglia) or changes in the learning of stimulus representations (in the hippocampal region) can have similar functional effects. PMID:20728258

Quantum communication complexity of establishing a shared reference frame.

PubMed

Rudolph, Terry; Grover, Lov

2003-11-21

We discuss the aligning of spatial reference frames from a quantum communication complexity perspective. This enables us to analyze multiple rounds of communication and give several simple examples demonstrating tradeoffs between the number of rounds and the type of communication. Using a distributed variant of a quantum computational algorithm, we give an explicit protocol for aligning spatial axes via the exchange of spin-1/2 particles which makes no use of either exchanged entangled states, or of joint measurements. This protocol achieves a worst-case fidelity for the problem of "direction finding" that is asymptotically equivalent to the optimal average case fidelity achievable via a single forward communication of entangled states.

Presentation of Aural Stimuli to Newborns and Premature Infants: An Audiological Perspective.

PubMed

Cassidy

1999-01-01

The purpose of this study was twofold: (a) to examine extant research in the field of music with premature and full term infants in order to identify protocols being used in the presentation of musical stimuli to neonates and (b) to use knowledge gleaned from audiology as a basis for suggesting a standardized protocol for use of musical stimuli with infants. Articles considered appropriate for inclusion in the analysis met the following criteria: (a) presented data for the effects of music on a dependent measure, (b) had subjects who were identified as either premature or term newborns receiving treatment after birth and prior to discharge from the hospital, and (c) used music for some or all of the aural stimuli. Articles (N = 20) were categorized by demographic information, types of aural stimuli, independent variables, dependent measures, and protocol used to present the musical stimuli. Of primary importance to this study was the protocol used in each study to present musical stimuli. Data regarding total duration of stimuli per day, longest duration of stimuli per day, method of stimuli presentation, placement of speakers, decibel level of stimuli, and where;he decibel level was measured reveal that there is no standard protocol being followed with regard to the presentation of aural stimuli. Recommendations include future research on (a) determining a minimum gestational age where music therapy may be appropriate, (b) determining the frequency spectrum perceived by a premature infant, (c) determining the decibel levels reaching the ear drum and assessing appropriate levels for minimum stimulation with maximum results, and (d) carefully considering the method of stimulus presentation as it will have an impact on the decibel level reaching the ear drum of these infants.

Optimizing otoacoustic emission protocols for a UNHS program.

PubMed

Hatzopoulos, S; Petruccelli, J; Ciorba, A; Martini, A

2009-01-01

To identify the optimal test protocol to screen for hearing problems in newborns, an evaluation of three distortion product otoacoustic emission (DPOAE) protocols was conducted in neonates, from a well-baby nursery (WBN) and from a neonatal intensive care unit (NICU) and compared to the performance in newborns of a more standard protocol based on transient-evoked OAEs (TEOAEs). The DPOAE protocols used asymmetrical stimulus intensities (L(1) > L(2)) with a frequency ratio of 1.22, in the following format: (P1), L(1) = 60, L(2) = 50 dB SPL; (P2), L(1) = 65, L(2) = 55 dB SPL, and (P3), L(1) = 75, L(2) = 65 dB SPL. Linear TEOAE responses, evoked by click stimuli of 75 dB peSPL, were used as controls of normal cochlear function. Five frequencies at 1.5, 2.0, 3.0, 4.0 and 5.0 kHz were tested with a common commercially available macro-based software subroutine (Otodynamics Corp, ILO-92). The project evaluated the responses from 1200 WBN infants (average age 48 h) and 350 low-birth-weight NICU infants, all randomly selected. Statistical analyses comparing the signal-to-noise ratios (S/N), at the predefined f(2) frequencies, indicated that the P1 and P2 DPOAE protocols generated similar responses. Significant S/N differences were observed in the P3 to P2 dataset comparisons. DPOAE scoring criteria were estimated from the P3 dataset using a one-sided, distribution-free confidence intervals. The scoring criteria for a 'pass' were estimated as a minimum S/N of 6.0, 7.0 and 6.0 dB at 2.0, 3.0 and 4.0 kHz, respectively. In terms of feasibility, the P3 protocol generated responses in 98% of the WBN and 94.8% of the NICU infants. All three DPOAE protocols demonstrated shorter time-recording requirements than the standard TEOAE test. The false-positive and false-negative rates for the NICU infants were estimated as 0.0028 and 0.003%, respectively.

SU-E-T-620: Dosimetric Compliance Study for a New Prostate Protocol of Combined High Dose Rate Brachytherapy and Stereotactic Body Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, C; Giaddui, T; Den, R

2014-06-15

Purpose: To investigate the adherence of treatment plans of prostate cancer patients with the dosimetric compliance criteria of the new in house phase I trial of high dose rate (HDR) brachytherapy combined with stereotactic body radiotherapy (SBRT) for intermediate risk prostate cancer patients. Methods: Ten prostate cancer patients were treated using this trial. They received one fraction of HDR to 15Gy, followed by external beam(EB) boost of 3.2Gy(Level 1, five patients) or 3.94Gy(level 2, five patients) per fraction for 10 or 7 fractions, respectively, both equivalent to EB treatments of 113.5Gy in 2Gy fractions. The EB plans were either IMRTmore » or VMAT plans. DVH analysis was performed to verify the adherence of treatment plans to the dosimetric criteria of the trial. Results: For Level 1 patients, target coverage were adequate, with CTV V32Gy(%) of 99.0±1.0 (mean ± 1 standard deviation), and PTV V31Gy(%) of 99.6±0.3. PTV V32.9Gy(%) is 1.4±3.1 and PTVmax is 32.9±0.2Gy. Rectum, bladder and femoral heads sparing were well within protocol criteria. For Level 2 patients, CTV V27.6Gy(%) is 98.7±1.8; PTV V26.7Gy(%) is 99.0±1.4. PTV V28.4Gy(%) is 1.3±1.4, with three patients having minor deviation from protocol. Again critical structures were spared compliant to the protocol. The analysis of HDR plans show similar results, with adequate dose coverage to the prostate and sparing of critical structures including urethra and rectum. V100(%) and V90(%) of prostate are 96.0±1.1 and 98.9±0.5. Urethra D10(%) is 113.1±2.9. Rectum V80(cc) is 1.4±0.5. Hotspot in prostate is substantially higher than what the protocol specifies. But the criteria for hotspot are only guidelines, serving to lower the dose to urethra . Conclusion: This new high biological equivalent dose prostate trial has been carried out successfully for ten patients. Based on dosimetric analysis, all HDR and external plans were compliant to the protocol criteria, with only minor deviations.« less

Assessing analgesia equivalence and appetite following alfaxalone- or ketamine-based injectable anesthesia for feline castration as an example of enhanced recovery after surgery.

PubMed

Armstrong, Tatum; Wagner, Marika C; Cheema, Jagjit; Pang, Daniel Sj

2018-02-01

Objectives The primary study objective was to assess two injectable anesthetic protocols, given to facilitate castration surgery in cats, for equivalence in terms of postoperative analgesia. A secondary objective was to evaluate postoperative eating behavior. Methods Male cats presented to a local clinic were randomly assigned to receive either intramuscular ketamine (5 mg/kg, n = 26; KetHD) or alfaxalone (2 mg/kg, n = 24; AlfHD) in combination with dexmedetomidine (25 μg/kg) and hydromorphone (0.05 mg/kg). All cats received meloxicam (0.3 mg/kg SC) and intratesticular lidocaine (2 mg/kg). Species-specific pain and sedation scales were applied at baseline, 1, 2 and 4 h postoperatively. Time taken to achieve sternal recumbency and begin eating were also recorded postoperatively. Results Pain scale scores were low and showed equivalence between the treatment groups at all time points (1 h, P = 0.38, 95% confidence interval [CI] of the difference between group scores 0-0; 2 h, P = 0.71, 95% CI 0-0; 4 h, P = 0.97, 95% CI 0-0). Four cats crossed the threshold for rescue analgesia (KetHD, n = 1; AlfHD, n = 3). At 1 h, more cats in the KetHD (65%) group than in the AlfHD (42%) group were sedated, but statistical significance was not detected ( P = 0.15, 95% CI -1 to 0). Most AlfHD cats (88%) began eating by 1 h vs 65% of KetHD cats ( P = 0.039). Time to recover sternal recumbency did not differ between groups ( P = 0.86, 95% CI -14.1 to 11.8). Conclusions and relevance These results show that AlfHD and KetHD provide equivalent analgesia as part of a multimodal injectable anesthetic protocol. Alfaxalone is associated with an earlier return to eating.

Ambulatory Treatment of Fast Breathing in Young Infants Aged <60 Days: A Double-Blind, Randomized, Placebo-Controlled Equivalence Trial in Low-Income Settlements of Karachi

PubMed Central

Muhammad, Amber A.; Shafiq, Yasir; Shah, Saima; Kumar, Naresh; Ahmed, Imran; Azam, Iqbal; Pasha, Omrana; Zaidi, Anita K. M.

2017-01-01

Abstract Background. Integrated Management of Childhood Illness recommends that young infants with isolated fast breathing be referred to a hospital for antibiotic treatment, which is often impractical in resource-limited settings. Additionally, antibiotics may be unnecessary for physiologic tachypnea in otherwise well newborns. We tested the hypothesis that ambulatory treatment with oral amoxicillin for 7 days was equivalent (similarity margin of 3%) to placebo in young infants with isolated fast breathing in primary care settings where hospital referral is often unfeasible. Methods. This randomized equivalence trial was conducted in 4 primary health centers of Karachi, Pakistan. Infants presenting with isolated fast breathing and oxygen saturation ≥90% were randomly assigned to receive either oral amoxicillin or placebo twice daily for 7 days. Enrolled infants were followed on days 1–8, 11, and 14. The primary outcome was treatment failure by day 8, analyzed per protocol. The trial was stopped by the data safety monitoring board due to higher treatment failure rate and the occurrence of 2 deaths in the placebo arm in an interim analysis. Results. Four hundred twenty-three infants fulfilled per protocol criteria in the amoxicillin arm and 426 in the placebo arm. Twelve infants (2.8%) had treatment failure in the amoxicillin arm and 25 (5.9%) in the placebo arm (risk difference, 3.1; P value .04). Two infants in the placebo arm died, whereas no deaths occurred in the amoxicillin arm. Other adverse outcomes, as well as the proportions of relapse, were evenly distributed across both study arms. Conclusions. This trial failed to show equivalence of placebo to amoxicillin in the management of isolated fast breathing without hypoxemia or other clinical signs of illness in term young infants. Clinical Trials Registration. NCT01533818. PMID:27941119

Anaemia management protocols in the care of haemodialysis patients: examining patient outcomes.

PubMed

Saunders, Sushila; MacLeod, Martha L P; Salyers, Vince; MacMillan, Peter D; Ogborn, Malcolm R

2013-08-01

To determine whether the use of a nurse-driven protocol in the haemodialysis setting is as safe and effective as traditional physician-driven approaches to anaemia management. The role of haemodialysis nurses in renal anaemia management has evolved through the implementation of nurse-driven protocols, addressing the trend of exceeding haemoglobin targets and rising costs of erythropoietin-stimulating agents. Retrospective, non-equivalent case control group design. The sample was from three haemodialysis units in a control group (n = 64) and three haemodialysis units in a protocol group (n = 43). The protocol group used a nurse-driven renal anaemia management protocol, while the control group used a traditional physician-driven approach to renal anaemia management. All retrospective data were obtained from a provincial renal database. Data were analysed using chi-square tests and t-tests. Patient outcomes examined were haemoglobin levels, transferrin saturation levels, erythropoietin-stimulating agents use and intravenous iron use. Cost comparisons were determined using average use of erythropoietin-stimulating agents and intravenous iron. Control and protocol groups reached haemoglobin target levels. In the protocol group, 75% reached transferrin saturation target levels in comparison with 25% of the control group. Use and costs for iron was higher in the control group, while use and costs for erythropoietin was higher in the protocol group. The higher usage of erythropoietin-stimulating agents was potentially related to comorbid conditions amongst the protocol group. A nurse-driven protocol approach to renal anaemia management was as effective as the physician-driven approach in reaching haemoglobin and transferrin saturation levels. Further examination of the use and dosing of erythropoietin-stimulating agents and intravenous iron, their impact on haemoglobin levels related to patient comorbidities and subsequent cost effectiveness of protocols is required. Using a nurse-driven protocol in practice supports the independent nursing role while contributing to safe patient outcomes. © 2013 Blackwell Publishing Ltd.

Ambulation During Periods of Supersaturation Increase Decompression Stress in Spacewalk Simulations

NASA Technical Reports Server (NTRS)

Pollock, N. W.; Natoli, M. J.; Martina, S. D.; Conkin, J.; Wessel, J. H., III; Gernhardt, M. L.

2016-01-01

Musculoskeletal activity accelerates inert gas elimination during oxygen breathing prior to decompression (prebreathe), but may also promote bubble formation (nucleation) and increase the risk of decompression sickness (DCS). The timing, pattern and intensity of musculoskeletal activity and the level of tissue supersaturation are likely critical to the net effect. Understanding the relationships is important to evaluate exercise prebreathe protocols and quantify decompression risk in gravity and microgravity environments. The NASA Prebreathe Reduction Program (PRP) combined oxygen prebreathe and exercise preceding a low pressure (4.3 psia; altitude equivalent of 30,300 ft [9,235 m]) simulation exposure of non-ambulatory subjects (a microgravity analog) to produce two protocols now used by astronauts preparing for extravehicular activity. One protocol included both upright cycling and non-cycling exercise (CEVIS: 'cycle ergometer vibration isolation system') and one protocol relied on non-cycling exercise only (ISLE: 'in-suit light exercise'). CEVIS trial data serve as control data for the current study to investigate the influence of ambulation exercise in 1G environments on bubble formation and the subsequent risk of DCS.

Attentional Selection of Feature Conjunctions Is Accomplished by Parallel and Independent Selection of Single Features.

PubMed

Andersen, Søren K; Müller, Matthias M; Hillyard, Steven A

2015-07-08

Experiments that study feature-based attention have often examined situations in which selection is based on a single feature (e.g., the color red). However, in more complex situations relevant stimuli may not be set apart from other stimuli by a single defining property but by a specific combination of features. Here, we examined sustained attentional selection of stimuli defined by conjunctions of color and orientation. Human observers attended to one out of four concurrently presented superimposed fields of randomly moving horizontal or vertical bars of red or blue color to detect brief intervals of coherent motion. Selective stimulus processing in early visual cortex was assessed by recordings of steady-state visual evoked potentials (SSVEPs) elicited by each of the flickering fields of stimuli. We directly contrasted attentional selection of single features and feature conjunctions and found that SSVEP amplitudes on conditions in which selection was based on a single feature only (color or orientation) exactly predicted the magnitude of attentional enhancement of SSVEPs when attending to a conjunction of both features. Furthermore, enhanced SSVEP amplitudes elicited by attended stimuli were accompanied by equivalent reductions of SSVEP amplitudes elicited by unattended stimuli in all cases. We conclude that attentional selection of a feature-conjunction stimulus is accomplished by the parallel and independent facilitation of its constituent feature dimensions in early visual cortex. The ability to perceive the world is limited by the brain's processing capacity. Attention affords adaptive behavior by selectively prioritizing processing of relevant stimuli based on their features (location, color, orientation, etc.). We found that attentional mechanisms for selection of different features belonging to the same object operate independently and in parallel: concurrent attentional selection of two stimulus features is simply the sum of attending to each of those features separately. This result is key to understanding attentional selection in complex (natural) scenes, where relevant stimuli are likely to be defined by a combination of stimulus features. Copyright © 2015 the authors 0270-6474/15/359912-08$15.00/0.

Chaos-induced modulation of reliability boosts output firing rate in downstream cortical areas.

PubMed

Tiesinga, P H E

2004-03-01

The reproducibility of neural spike train responses to an identical stimulus across different presentations (trials) has been studied extensively. Reliability, the degree of reproducibility of spike trains, was found to depend in part on the amplitude and frequency content of the stimulus [J. Hunter and J. Milton, J. Neurophysiol. 90, 387 (2003)]. The responses across different trials can sometimes be interpreted as the response of an ensemble of similar neurons to a single stimulus presentation. How does the reliability of the activity of neural ensembles affect information transmission between different cortical areas? We studied a model neural system consisting of two ensembles of neurons with Hodgkin-Huxley-type channels. The first ensemble was driven by an injected sinusoidal current that oscillated in the gamma-frequency range (40 Hz) and its output spike trains in turn drove the second ensemble by fast excitatory synaptic potentials with short term depression. We determined the relationship between the reliability of the first ensemble and the response of the second ensemble. In our paradigm the neurons in the first ensemble were initially in a chaotic state with unreliable and imprecise spike trains. The neurons became entrained to the oscillation and responded reliably when the stimulus power was increased by less than 10%. The firing rate of the first ensemble increased by 30%, whereas that of the second ensemble could increase by an order of magnitude. We also determined the response of the second ensemble when its input spike trains, which had non-Poisson statistics, were replaced by an equivalent ensemble of Poisson spike trains. The resulting output spike trains were significantly different from the original response, as assessed by the metric introduced by Victor and Purpura [J. Neurophysiol. 76, 1310 (1996)]. These results are a proof of principle that weak temporal modulations in the power of gamma-frequency oscillations in a given cortical area can strongly affect firing rate responses downstream by way of reliability in spite of rather modest changes in firing rate in the originating area.

Equivalence of ELISpot Assays Demonstrated between Major HIV Network Laboratories

PubMed Central

Levine, Gail L.; Sambor, Anna; Carter, Donald K.; Sato, Alicia; Kopycinski, Jakub; Hayes, Peter; Hahn, Bridget; Birungi, Josephine; Tarragona-Fiol, Tony; Wan, Hong; Randles, Mark; Cooper, Andrew Raxworthy; Ssemaganda, Aloysius; Clark, Lorna; Kaleebu, Pontiano; Self, Steven G.; Koup, Richard; Wood, Blake; McElrath, M. Juliana; Cox, Josephine H.; Hural, John; Gilmour, Jill

2010-01-01

Background The Comprehensive T Cell Vaccine Immune Monitoring Consortium (CTC-VIMC) was created to provide standardized immunogenicity monitoring services for HIV vaccine trials. The ex vivo interferon-gamma (IFN-γ) ELISpot is used extensively as a primary immunogenicity assay to assess T cell-based vaccine candidates in trials for infectious diseases and cancer. Two independent, GCLP-accredited central laboratories of CTC-VIMC routinely use their own standard operating procedures (SOPs) for ELISpot within two major networks of HIV vaccine trials. Studies are imperatively needed to assess the comparability of ELISpot measurements across laboratories to benefit optimal advancement of vaccine candidates. Methods We describe an equivalence study of the two independently qualified IFN-g ELISpot SOPs. The study design, data collection and subsequent analysis were managed by independent statisticians to avoid subjectivity. The equivalence of both response rates and positivity calls to a given stimulus was assessed based on pre-specified acceptance criteria derived from a separate pilot study. Findings Detection of positive responses was found to be equivalent between both laboratories. The 95% C.I. on the difference in response rates, for CMV (−1.5%, 1.5%) and CEF (−0.4%, 7.8%) responses, were both contained in the pre-specified equivalence margin of interval [−15%, 15%]. The lower bound of the 95% C.I. on the proportion of concordant positivity calls for CMV (97.2%) and CEF (89.5%) were both greater than the pre-specified margin of 70%. A third CTC-VIMC central laboratory already using one of the two SOPs also showed comparability when tested in a smaller sub-study. Interpretation The described study procedure provides a prototypical example for the comparison of bioanalytical methods in HIV vaccine and other disease fields. This study also provides valuable and unprecedented information for future vaccine candidate evaluations on the comparison and pooling of ELISpot results generated by the CTC-VIMC central core laboratories. PMID:21179404

Protein substitute dosage in PKU: how much do young patients need?

PubMed

MacDonald, A; Chakrapani, A; Hendriksz, C; Daly, A; Davies, P; Asplin, D; Hall, K; Booth, I W

2006-07-01

The optimal dose of protein substitute has not been determined in children with phenylketonuria (PKU). To determine if a lower dose of protein substitute could achieve the same or better degree of blood phenylalanine control when compared to the dosage recommended by the UK MRC.(1) In a six week randomised, crossover study, two doses of protein substitute (Protocol A: 2 g/kg/day of protein equivalent; Protocol B: 1.2 g/kg/day protein equivalent) were compared in 25 children with well controlled PKU aged 2-10 years (median 6 years). Each dose of protein substitute was taken for 14 days, with a 14 day washout period in between. Twice daily blood samples (fasting pre-breakfast and evening, at standard times) for plasma phenylalanine were taken on day 8-14 of each protocol. The median usual dose of protein substitute was 2.2 g/kg/day (range 1.5-3.1 g/kg/day). When compared with control values, median plasma phenylalanine on the low dose of protein substitute increased at pre-breakfast by 301 mumol/l (95% CI 215 to 386) and in the evening by 337 micromol/l (95% CI 248 to 431). On the high dose of protein substitute, plasma phenylalanine concentrations remained unchanged when compared to control values. However, wide variability was seen between subjects. A higher dosage of protein substitute appeared to contribute to lower blood phenylalanine concentrations in PKU, but it did have a variable and individual impact and may have been influenced by the carbohydrate (+/- fat) content of the protein substitute.

Terminator Disparity Contributes to Stereo Matching for Eye Movements and Perception

PubMed Central

Optican, Lance M.; Cumming, Bruce G.

2013-01-01

In the context of motion detection, the endings (or terminators) of 1-D features can be detected as 2-D features, affecting the perceived direction of motion of the 1-D features (the barber-pole illusion) and the direction of tracking eye movements. In the realm of binocular disparity processing, an equivalent role for the disparity of terminators has not been established. Here we explore the stereo analogy of the barber-pole stimulus, applying disparity to a 1-D noise stimulus seen through an elongated, zero-disparity, aperture. We found that, in human subjects, these stimuli induce robust short-latency reflexive vergence eye movements, initially in the direction orthogonal to the 1-D features, but shortly thereafter in the direction predicted by the disparity of the terminators. In addition, these same stimuli induce vivid depth percepts, which can only be attributed to the disparity of line terminators. When the 1-D noise patterns are given opposite contrast in the two eyes (anticorrelation), both components of the vergence response reverse sign. Finally, terminators drive vergence even when the aperture is defined by a texture (as opposed to a contrast) boundary. These findings prove that terminators contribute to stereo matching, and constrain the type of neuronal mechanisms that might be responsible for the detection of terminator disparity. PMID:24285893

Terminator disparity contributes to stereo matching for eye movements and perception.

PubMed

Quaia, Christian; Optican, Lance M; Cumming, Bruce G

2013-11-27

In the context of motion detection, the endings (or terminators) of 1-D features can be detected as 2-D features, affecting the perceived direction of motion of the 1-D features (the barber-pole illusion) and the direction of tracking eye movements. In the realm of binocular disparity processing, an equivalent role for the disparity of terminators has not been established. Here we explore the stereo analogy of the barber-pole stimulus, applying disparity to a 1-D noise stimulus seen through an elongated, zero-disparity, aperture. We found that, in human subjects, these stimuli induce robust short-latency reflexive vergence eye movements, initially in the direction orthogonal to the 1-D features, but shortly thereafter in the direction predicted by the disparity of the terminators. In addition, these same stimuli induce vivid depth percepts, which can only be attributed to the disparity of line terminators. When the 1-D noise patterns are given opposite contrast in the two eyes (anticorrelation), both components of the vergence response reverse sign. Finally, terminators drive vergence even when the aperture is defined by a texture (as opposed to a contrast) boundary. These findings prove that terminators contribute to stereo matching, and constrain the type of neuronal mechanisms that might be responsible for the detection of terminator disparity.

Two-tone suppression in the cricket, Eunemobius carolinus (Gryllidae, Nemobiinae)

NASA Astrophysics Data System (ADS)

Farris, Hamilton E.; Hoy, Ronald R.

2002-03-01

Sounds with frequencies >15 kHz elicit an acoustic startle response (ASR) in flying crickets (Eunemobius carolinus). Although frequencies <15 kHz do not elicit the ASR when presented alone, when presented with ultrasound (40 kHz), low-frequency stimuli suppress the ultrasound-induced startle. Thus, using methods similar to those in masking experiments, we used two-tone suppression to assay sensitivity to frequencies in the audio band. Startle suppression was tuned to frequencies near 5 kHz, the frequency range of male calling songs. Similar to equal loudness contours measured in humans, however, equal suppression contours were not parallel, as the equivalent rectangular bandwidth of suppression tuning changed with increases in ultrasound intensity. Temporal integration of suppressor stimuli was measured using nonsimultaneous presentations of 5-ms pulses of 6 and 40 kHz. We found that no suppression occurs when the suppressing tone is >2 ms after and >5 ms before the ultrasound stimulus, suggesting that stimulus overlap is a requirement for suppression. When considered together with our finding that the intensity of low-frequency stimuli required for suppression is greater than that produced by singing males, the overlap requirement suggests that two-tone suppression functions to limit the ASR to sounds containing only ultrasound and not to broadband sounds that span the audio and ultrasound range.

Males and females show differential brain activation to taste when hungry and sated in gustatory and reward areas

PubMed Central

Haase, Lori; Green, Erin; Murphy, Claire

2011-01-01

Although males and females differ in eating behavior and prevalence rates for eating disorders and obesity, little is known about gender differences in cortical activation to pleasant and unpleasant pure tastes during the physiological states of hunger and satiety. Twenty-one healthy young adults (12 females and 9 males) underwent two functional magnetic resonance imaging scans. Using four pure tastants of differing qualities (i.e., salty, sour, bitter, sweet), the present study examined gender differences in fMRI activation during two motivational states (hunger and satiety). There was greater change in fMRI activation from hunger to satiety in males than females in response to all tastes within the middle frontal gyrus (BA 10), insula, and cerebellum. Males also had greater change in activation from hunger to satiety, relative to females, in limbic regions including dorsal striatum, amygdala, parahippocampal gyrus, and posterior and anterior cingulate; however, activation was stimulus dependent, despite equivalent ratings in perceived pleasantness and intensity. Interestingly, males and females showed significant change from hunger to satiety in response to citric acid, suggesting that in addition to gender and physiological condition, stimulus quality is an important factor in taste fMRI activation. These gender differences may have implications for the pathophysiology of eating disorders and obesity. PMID:21718731

Thresholding of auditory cortical representation by background noise

PubMed Central

Liang, Feixue; Bai, Lin; Tao, Huizhong W.; Zhang, Li I.; Xiao, Zhongju

2014-01-01

It is generally thought that background noise can mask auditory information. However, how the noise specifically transforms neuronal auditory processing in a level-dependent manner remains to be carefully determined. Here, with in vivo loose-patch cell-attached recordings in layer 4 of the rat primary auditory cortex (A1), we systematically examined how continuous wideband noise of different levels affected receptive field properties of individual neurons. We found that the background noise, when above a certain critical/effective level, resulted in an elevation of intensity threshold for tone-evoked responses. This increase of threshold was linearly dependent on the noise intensity above the critical level. As such, the tonal receptive field (TRF) of individual neurons was translated upward as an entirety toward high intensities along the intensity domain. This resulted in preserved preferred characteristic frequency (CF) and the overall shape of TRF, but reduced frequency responding range and an enhanced frequency selectivity for the same stimulus intensity. Such translational effects on intensity threshold were observed in both excitatory and fast-spiking inhibitory neurons, as well as in both monotonic and nonmonotonic (intensity-tuned) A1 neurons. Our results suggest that in a noise background, fundamental auditory representations are modulated through a background level-dependent linear shifting along intensity domain, which is equivalent to reducing stimulus intensity. PMID:25426029

The Contrast Sensitivity of the Newborn Human Infant

PubMed Central

Brown, Angela M.; Lindsey, Delwin T.; Cammenga, Joanna G.; Giannone, Peter J.; Stenger, Michael R.

2015-01-01

Purpose. To measure the binocular contrast sensitivity (CS) of newborn infants using a fixation-and-following card procedure. Methods. The CS of 119 healthy newborn infants was measured using stimuli printed on cards under the descending method of limits (93 infants) and randomized/masked designs (26 infants). One experienced and one novice adult observer tested the infants using vertical square-wave gratings (0.06 and 0.10 cyc/deg; 20/10,000 and 20/6000 nominal Snellen equivalent); the experienced observer also tested using horizontal gratings (0.10 cyc/deg) and using the Method of Constant Stimuli while being kept unaware of the stimulus values. Results. The CS of the newborn infant was 2.0 (contrast threshold = 0.497; 95% confidence interval: 0.475–0.524) for vertically oriented gratings and 1.74 (threshold = 0.575; 95% confidence interval: 0.523–0.633) for horizontally oriented gratings (P < 0.0006). The standard deviation of infant CS was comparable to that obtained by others on adults using the Pelli-Robson chart. The two observers showed similar practice effects. Randomization of stimulus order and masking of the adult observer had no effect on CS. Conclusions. The CS of individual newborn human infants can be measured using a fixation-and-following card procedure. PMID:25564453

Both trace and delay conditioned eyeblink responding can be dissociated from outcome expectancy.

PubMed

Weidemann, Gabrielle; Broderick, Joshua; Lovibond, Peter F; Mitchell, Christopher J

2012-01-01

Squire and colleagues have proposed that trace and delay eyeblink conditioning are fundamentally different kinds of learning: trace conditioning requires acquisition of a conscious declarative memory for the stimulus contingencies whereas delay conditioning does not. Declarative memory in trace conditioning is thought to generate conditioned responding through the activation of a conscious expectancy for when the unconditioned stimulus (US) is going to occur. Perruchet (1985) has previously shown that in a 50% partial reinforcement design it is possible to dissociate single cue delay eyeblink conditioning from conscious expectancy for the US by examining performance over runs of reinforced and nonreinforced trials. Clark, Manns, and Squire (2001) claim that this dissociation does not occur in trace eyeblink conditioning. In the present experiment we examined the Perruchet effect for short, moderate, and long trace intervals (600, 1000, and 1400 ms) and for the equivalent interstimulus intervals (ISIs) in a delay conditioning procedure. We found evidence for a dissociation of eyeblink CRs and US expectancy over runs regardless of whether there was a delay or a trace arrangement of cues. The reasons for the Perruchet effect are still unclear, but the present data suggest that it does not depend on a separate nondeclarative system of the type proposed by Squire and colleagues. (c) 2012 APA, all rights reserved.

Neural basis of superior performance of action videogame players in an attention-demanding task.

PubMed

Mishra, Jyoti; Zinni, Marla; Bavelier, Daphne; Hillyard, Steven A

2011-01-19

Steady-state visual evoked potentials (SSVEPs) were recorded from action videogame players (VGPs) and from non-videogame players (NVGPs) during an attention-demanding task. Participants were presented with a multi-stimulus display consisting of rapid sequences of alphanumeric stimuli presented at rates of 8.6/12 Hz in the left/right peripheral visual fields, along with a central square at fixation flashing at 5.5 Hz and a letter sequence flashing at 15 Hz at an upper central location. Subjects were cued to attend to one of the peripheral or central stimulus sequences and detect occasional targets. Consistent with previous behavioral studies, VGPs detected targets with greater speed and accuracy than NVGPs. This behavioral advantage was associated with an increased suppression of SSVEP amplitudes to unattended peripheral sequences in VGPs relative to NVGPs, whereas the magnitude of the attended SSVEPs was equivalent in the two groups. Group differences were also observed in the event-related potentials to targets in the alphanumeric sequences, with the target-elicited P300 component being of larger amplitude in VGPS than NVGPs. These electrophysiological findings suggest that the superior target detection capabilities of the VGPs are attributable, at least in part, to enhanced suppression of distracting irrelevant information and more effective perceptual decision processes.

Accurate Encoding and Decoding by Single Cells: Amplitude Versus Frequency Modulation

PubMed Central

Micali, Gabriele; Aquino, Gerardo; Richards, David M.; Endres, Robert G.

2015-01-01

Cells sense external concentrations and, via biochemical signaling, respond by regulating the expression of target proteins. Both in signaling networks and gene regulation there are two main mechanisms by which the concentration can be encoded internally: amplitude modulation (AM), where the absolute concentration of an internal signaling molecule encodes the stimulus, and frequency modulation (FM), where the period between successive bursts represents the stimulus. Although both mechanisms have been observed in biological systems, the question of when it is beneficial for cells to use either AM or FM is largely unanswered. Here, we first consider a simple model for a single receptor (or ion channel), which can either signal continuously whenever a ligand is bound, or produce a burst in signaling molecule upon receptor binding. We find that bursty signaling is more accurate than continuous signaling only for sufficiently fast dynamics. This suggests that modulation based on bursts may be more common in signaling networks than in gene regulation. We then extend our model to multiple receptors, where continuous and bursty signaling are equivalent to AM and FM respectively, finding that AM is always more accurate. This implies that the reason some cells use FM is related to factors other than accuracy, such as the ability to coordinate expression of multiple genes or to implement threshold crossing mechanisms. PMID:26030820

Design and testing of low intensity laser biostimulator.

PubMed

Valchinov, Emil S; Pallikarakis, Nicolas E

2005-01-13

The non-invasive nature of laser biostimulation has made lasers an attractive alternative in Medical Acupuncture at the last 25 years. However, there is still an uncertainty as to whether they work or their effect is just placebo. Although a plethora of scientific papers published about the topic showing positive clinical results, there is still a lack of objective scientific proofs about the biostimulation effect of lasers in Medical Acupuncture. The objective of this work was to design and build a low cost portable laser device for stimulation of acupuncture points, considered here as small localized biosources (SLB), without stimulating any sensory nerves via shock or heat and to find out a suitable method for objectively evaluating its stimulating effect. The design is aimed for studying SLB potentials provoked by laser stimulus, in search for objective proofs of the biostimulation effect of lasers used in Medical Acupuncture. The proposed biostimulator features two operational modes: program mode and stimulation mode and two output polarization modes: linearly and circularly polarized laser emission. In program mode, different user-defined stimulation protocols can be created and memorized. The laser output can be either continuous or pulse modulated. Each stimulation session consists of a pre-defined number of successive continuous or square pulse modulated sequences of laser emission. The variable parameters of the laser output are: average output power, pulse width, pulse period, and continuous or pulsed sequence duration and repetition period. In stimulation mode the stimulus is automatically applied according to the pre-programmed protocol. The laser source is 30 mW AlGaInP laser diode with an emission wavelength of 685 nm, driven by a highly integrated driver. The optical system designed for beam collimation and polarization change uses single collimating lens with large numerical aperture, linear polarizer and a quarter-wave retardation plate. The proposed method for testing the device efficiency employs a biofeedback from the subject by recording the biopotentials evoked by the laser stimulus at related distant SLB sites. Therefore measuring of SLB biopotentials caused by the stimulus would indicate that a biopotential has been evoked at the irradiated site and has propagated to the measurement sites, rather than being caused by local changes of the electrical skin conductivity. A prototype device was built according to the proposed design using relatively inexpensive and commercially available components. The laser output can be pulse modulated from 0.1 to 1000 Hz with a duty factor from 10 to 90%. The average output power density can be adjusted in the range 24-480 mW/cm2, where the total irradiation is limited to 2 Joule per stimulation session. The device is controlled by an 8-bit RISC Flash microcontroller with internal RAM and EEPROM memory, which allows for a wide range of different stimulation protocols to be implemented and memorized. The integrated laser diode driver with its onboard light power control loop provides safe and consistent laser modulation. The prototype was tested on the right Tri-Heater (TH) acupuncture meridian according to the proposed method. Laser evoked potentials were recorded from most of the easily accessible SLB along the meridian under study. They appear like periodical spikes with a repetition rate from 0.05 to 10 Hz and amplitude range 0.1-1 mV. The prototype's specifications were found to be better or comparable to those of other existing devices. It features low component count, small size and low power consumption. Because of the low power levels used the possibility of sensory nerve stimulation via the phenomenon of shock or heat is excluded. Thus senseless optical stimulation is achieved. The optical system presented offers simple and cost effective way for beam collimation and polarization change. The novel method proposed for testing the device efficiency allows for objectively recording of SLB potentials evoked by laser stimulus. Based on the biopotential records obtained with this method, a scientifically based conclusion can be drawn about the effectiveness of the commercially available devices for low-level laser therapy used in Medical Acupuncture. The prototype tests showed that with the biostimulator presented, SLB could be effectively stimulated at low power levels. However more studies are needed to derive a general conclusion about the SLB biostimulation mechanism of lasers and their most effective power and optical settings.

A second generation experiment in fault-tolerant software

NASA Technical Reports Server (NTRS)

Knight, J. C.

1986-01-01

The primary goal was to determine whether the application of fault tolerance to software increases its reliability if the cost of production is the same as for an equivalent nonfault tolerance version derived from the same requirements specification. Software development protocols are discussed. The feasibility of adapting to software design fault tolerance the technique of N-fold Modular Redundancy with majority voting was studied.

Evaluation of the appropriate use of a CIWA-Ar alcohol withdrawal protocol in the general hospital setting.

PubMed

Eloma, Amanda S; Tucciarone, Jason M; Hayes, Edmund M; Bronson, Brian D

2018-01-01

The Clinical Institute Withdrawal Assessment-Alcohol, Revised (CIWA-Ar) is an assessment tool used to quantify alcohol withdrawal syndrome (AWS) severity and inform benzodiazepine treatment for alcohol withdrawal. To evaluate the prescribing patterns and appropriate use of the CIWA-Ar protocol in a general hospital setting, as determined by the presence or absence of documented AWS risk factors, patients' ability to communicate, and provider awareness of the CIWA-Ar order. This retrospective chart review included 118 encounters of hospitalized patients placed on a CIWA-Ar protocol during one year. The following data were collected for each encounter: patient demographics, admitting diagnosis, ability to communicate, and admission blood alcohol level; and medical specialty of the clinician ordering CIWA-Ar, documentation of the presence or absence of established AWS risk factors, specific parameters of the protocol ordered, service admitted to, provider documentation of awareness of the active protocol within 48 h of initial order, total benzodiazepine dose equivalents administered and associated adverse events. 57% of patients who started on a CIWA-Ar protocol had either zero or one documented risk factor for AWS (19% and 38% respectively). 20% had no documentation of recent alcohol use. 14% were unable to communicate. 19% of medical records lacked documentation of provider awareness of the ordered protocol. Benzodiazepine associated adverse events were documented in 15% of encounters. The judicious use of CIWA-Ar protocols in general hospitals requires mechanisms to ensure assessment of validated alcohol withdrawal risk factors, exclusion of patients who cannot communicate, and continuity of care during transitions.

A cooled CCD camera-based protocol provides an effective solution for in vitro monitoring of luciferase.

PubMed

Afshari, Amirali; Uhde-Stone, Claudia; Lu, Biao

2015-03-13

Luciferase assay has become an increasingly important technique to monitor a wide range of biological processes. However, the mainstay protocols require a luminometer to acquire and process the data, therefore limiting its application to specialized research labs. To overcome this limitation, we have developed an alternative protocol that utilizes a commonly available cooled charge-coupled device (CCCD), instead of a luminometer for data acquiring and processing. By measuring activities of different luciferases, we characterized their substrate specificity, assay linearity, signal-to-noise levels, and fold-changes via CCCD. Next, we defined the assay parameters that are critical for appropriate use of CCCD for different luciferases. To demonstrate the usefulness in cultured mammalian cells, we conducted a case study to examine NFκB gene activation in response to inflammatory signals in human embryonic kidney cells (HEK293 cells). We found that data collected by CCCD camera was equivalent to those acquired by luminometer, thus validating the assay protocol. In comparison, The CCCD-based protocol is readily amenable to live-cell and high-throughput applications, offering fast simultaneous data acquisition and visual and quantitative data presentation. In conclusion, the CCCD-based protocol provides a useful alternative for monitoring luciferase reporters. The wide availability of CCCD will enable more researchers to use luciferases to monitor and quantify biological processes. Copyright © 2015 Elsevier Inc. All rights reserved.

Exercise Increases the Cardiovascular Stimulus Provided by Artificial Gravity

NASA Technical Reports Server (NTRS)

Howarth, M. S.; Moore, F. B.; Hinghofer-Szalkay, H.; Jezova, D.; Diedrich, A.; Ferris, M. B.; Schlegel, T. T.; Pathwardhan, A. R.; Knapp, C. F.; Evans, J. M.

2008-01-01

We investigated fluid shifts and regulatory responses to variations of posture, exercise, Gz level and radius of rotation in subjects riding NASA Ames 20G centrifuge. Results are from 4 protocols that address radius and exercise effects only. Protocol A: After 10 min supine control, 12 healthy men (35 plus or minus 9 yr, 82.8 plus or minus 7.9 kg) were exposed to rotational 1 Gz (2.5 m radius) for 2 min followed by 20 min alternating between 1 and 1.25 Gz. Blood samples were taken pre and post spin. Protocol B: Same as A, but lower limb exercise (70% V02max) preceded ramps to 1.25 Gz. Protocol C: Same as A but radius of rotation 8.3 m. Protocol D: Same as B but at 8.3 m. The 8 subjects who completed all protocols, increased heart rate (HR) from control, on average, by: A: 5, B: 39, C: 11, D: 44 bpm. For thoracic fluid volume, (bioimpedance), the 8 subjects changed from control, on average: A: -394, B: -548, C: -537, D: -708 mL. For thigh fluid volume, changes from control, on average, were: A: -137, B: 129, C: -75, D: 159 mL. Hematocrit changes from control were: A: 2.3, B: 3.5, C: 2.3, D: 4.3 %. Radius effects were mild and included greater loss of fluid from the thorax, less fluid loss from the thigh and increased heart rate at the longer radius. Pre-acceleration exercise effects were more dramatic and included additional loss of fluid from the chest, increased fluid volume of the thigh, increased hematocrit and greater heart rate increases. We propose that short bouts of intense exercise can be used to magnify the cardiovascular stress delivered by artificial gravity (AG) training and the combination of AG with exercise training can be fine-tuned to preserve orthostatic tolerance of astronauts during spaceflight.

Superconducting Qubits as Mechanical Quantum Engines

NASA Astrophysics Data System (ADS)

Sachtleben, Kewin; Mazon, Kahio T.; Rego, Luis G. C.

2017-09-01

We propose the equivalence of superconducting qubits with a pistonlike mechanical quantum engine. The work reports a study on the nature of the nonequilibrium work exchanged with the quantum-nonadiabatic working medium, which is modeled as a multilevel coupled quantum well system subject to an external control parameter. The quantum dynamics is solved for arbitrary control protocols. It is shown that the work output has two components: one that depends instantaneously on the level populations and another that is due to the quantum coherences built in the system. The nonadiabatic coherent dynamics of the quantum engine gives rise to a resistance (friction) force that decreases the work output. We consider the functional equivalence of such a device and a rf-SQUID flux qubit.

Diagnosis and management of somatosensory tinnitus: review article

PubMed Central

Sanchez, Tanit Ganz; Rocha, Carina Bezerra

2011-01-01

Tinnitus is the perception of sound in the absence of an acoustic external stimulus. It affects 10–17% of the world's population and it a complex symptom with multiple causes, which is influenced by pathways other than the auditory one. Recently, it has been observed that tinnitus may be provoked or modulated by stimulation arising from the somatosensorial system, as well as from the somatomotor and visual–motor systems. This specific subgroup – somatosensory tinnitus – is present in 65% of cases, even though it tends to be underdiagnosed. As a consequence, it is necessary to establish evaluation protocols and specific treatments focusing on both the auditory pathway and the musculoskeletal system. PMID:21808880

Development of techniques to enhance man/machine communication

NASA Technical Reports Server (NTRS)

Targ, R.; Cole, P.; Puthoff, H.

1974-01-01

A four-state random stimulus generator, considered to function as an ESP teaching machine was used to investigate an approach to facilitating interactions between man and machines. A subject tries to guess in which of four states the machine is. The machine offers the user feedback and reinforcement as to the correctness of his choice. Using this machine, 148 volunteer subjects were screened under various protocols. Several whose learning slope and/or mean score departed significantly from chance expectation were identified. Direct physiological evidence of perception of remote stimuli not presented to any known sense of the percipient using electroencephalographic (EEG) output when a light was flashed in a distant room was also studied.

Neural correlates of species-typical illogical cognitive bias in human inference.

PubMed

Ogawa, Akitoshi; Yamazaki, Yumiko; Ueno, Kenichi; Cheng, Kang; Iriki, Atsushi

2010-09-01

The ability to think logically is a hallmark of human intelligence, yet our innate inferential abilities are marked by implicit biases that often lead to illogical inference. For example, given AB ("if A then B"), people frequently but fallaciously infer the inverse, BA. This mode of inference, called symmetry, is logically invalid because, although it may be true, it is not necessarily true. Given pairs of conditional relations, such as AB and BC, humans reflexively perform two additional modes of inference: transitivity, whereby one (validly) infers AC; and equivalence, whereby one (invalidly) infers CA. In sharp contrast, nonhuman animals can handle transitivity but can rarely be made to acquire symmetry or equivalence. In the present study, human subjects performed logical and illogical inferences about the relations between abstract, visually presented figures while their brain activation was monitored with fMRI. The prefrontal, medial frontal, and intraparietal cortices were activated during all modes of inference. Additional activation in the precuneus and posterior parietal cortex was observed during transitivity and equivalence, which may reflect the need to retrieve the intermediate stimulus (B) from memory. Surprisingly, the patterns of brain activation in illogical and logical inference were very similar. We conclude that the observed inference-related fronto-parietal network is adapted for processing categorical, but not logical, structures of association among stimuli. Humans might prefer categorization over the memorization of logical structures in order to minimize the cognitive working memory load when processing large volumes of information.

Excimer laser: a module of the alopecia areata common protocol.

PubMed

McMichael, Amy J

2013-12-01

Alopecia areata (AA) is an autoimmune condition characterized by T cell-mediated attack of the hair follicle. The inciting antigenic stimulus is unknown. A dense perbulbar lymphocytic infiltrate and reproducible immunologic abnormalities are hallmark features of the condition. The cellular infiltrate primarily consists of activated T lymphocytes and antigen-presenting Langerhans cells. The xenon chloride excimer laser emits its total energy at the wavelength of 308 nm and therefore is regarded as a "super-narrowband" UVB light source. Excimer laser treatment is highly effective in psoriasis, another T cell-mediated disorder that shares many immunologic features with AA. The excimer laser is superior in inducing T cell apoptosis in vitro compared with narrowband UVB, with paralleled improved clinical efficacy. The excimer laser has been used successfully in patients with AA. In this context, evaluation of the potential benefit of 308-nm excimer laser therapy in the treatment of AA is clinically warranted. Herein, the use of a common treatment protocol with a specifically designed module to study the outcome of excimer laser treatment on moderate-to-severe scalp AA in adults is described.

Efficacy of attention bias modification using threat and appetitive stimuli: a meta-analytic review.

PubMed

Beard, Courtney; Sawyer, Alice T; Hofmann, Stefan G

2012-12-01

Attention bias modification (ABM) protocols aim to modify attentional biases underlying many forms of pathology. Our objective was to conduct an effect size analysis of ABM across a wide range of samples and psychological problems. We conducted a literature search using PubMed, PsycInfo, and author searches to identify randomized studies that examined the effects of ABM on attention and subjective experiences. We identified 37 studies (41 experiments) totaling 2,135 participants who were randomized to training toward neutral, positive, threat, or appetitive stimuli or to a control condition. The effect size estimate for changes in attentional bias was large for the neutral versus threat comparisons (g=1.06), neutral versus appetitive (g=1.41), and neutral versus control comparisons (g=0.80), and small for positive versus control (g=0.24). The effects of ABM on attention bias were moderated by stimulus type (words vs. pictures) and sample characteristics (healthy vs. high symptomatology). Effect sizes of ABM on subjective experiences ranged from 0.03 to 0.60 for postchallenge outcomes, -0.31 to 0.51 for posttreatment, and were moderated by number of training sessions, stimulus type, and stimulus orientation (top/bottom vs. left/right). Fail-safe N calculations suggested that the effect size estimates were robust for the training effects on attentional biases, but not for the effect on subjective experiences. ABM studies using threat stimuli produced significant effects on attention bias across comparison conditions, whereas appetitive stimuli produced changes in attention only when comparing appetitive versus neutral conditions. ABM has a moderate and robust effect on attention bias when using threat stimuli. Further studies are needed to determine whether these effects are also robust when using appetitive stimuli and for affecting subjective experiences. Copyright © 2012. Published by Elsevier Ltd.

On a method to detect long-latency excitations and inhibitions of single hand muscle motoneurons in man.

PubMed

Awiszus, F; Feistner, H; Schäfer, S S

1991-01-01

The peri-stimulus-time histogram (PSTH) analysis of stimulus-related neuronal spike train data is usually regarded as a method to detect stimulus-induced excitations or inhibitions. However, for a fairly regularly discharging neuron such as the human alpha-motoneuron, long-latency modulations of a PSTH are difficult to interpret as PSTH modulations can also occur as a consequence of a modulated neuronal autocorrelation. The experiments reported here were made (i) to investigate the extent to which a PSTH of a human hand-muscle motoneuron may be contaminated by features of the autocorrelation and (ii) to develop methods that display the motoneuronal excitations and inhibitions without such contamination. Responses of 29 single motor units to electrical ulnar nerve stimulation below motor threshold were investigated in the first dorsal interosseous muscle of three healthy volunteers using an experimental protocol capable of demonstrating the presence of autocorrelative modulations in the neuronal response. It was found for all units that the PSTH as well as the cumulative sum (CUSUM) derived from these responses were severely affected by the presence of autocorrelative features. On the other hand, calculating the CUSUM in a slightly modified form yielded--for all units investigated--a neuronal output feature sensitive only to motoneuronal excitations and inhibitions induced by the afferent volley. The price that has to be paid to arrive at such a modified CUSUM (mCUSUM) was a high computational effort prohibiting the on-line availability of this output feature during the experiment. It was found, however, that an interspike interval superposition plot (IISP)--easily obtainable during the experiment--is also free of autocorrelative features.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantifying Social Motivation in Mice Using Operant Conditioning.

PubMed

Martin, Loren; Iceberg, Erica

2015-08-08

In this protocol, social motivation is measured in mice through a pair of operant conditioning paradigms. To conduct the experiments, two-chambered shuttle boxes were equipped with two operant levers (left and right) and a food receptacle in one chamber, which was then divided from the second chamber by an automated guillotine door covered by a wire grid. Different stimulus mice, rotated across testing days, served as a social stimulus behind the wire grid, and were only visible following the opening of the guillotine door. Test mice were trained to lever press in order to open the door and gain access to the stimulus partner for 15 sec. The number of lever presses required to obtain the social reward progressively increased on a fixed schedule of 3. Testing sessions ended after test mice stopped lever pressing for 5 consecutive minutes. The last reinforced ratio or breakpoint can be used as a quantitative measure of social motivation. For the second paradigm, test mice were trained to discriminate between left and right lever presses in order to obtain either a food reward or the social reward. Mice were rewarded for every 3 presses of each respective lever. The number of food and social rewards can be compared as a measurement of the value placed upon each reward. The ratio of each reward type can also be compared between mouse strains and the change in this ratio can be monitored within testing sessions to measure satiation with a given reward type. Both of these operant conditioning paradigms are highly useful for the quantification of social motivation in mouse models of autism and other disorders of social behavior.

Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart

PubMed Central

Orini, Michele; Simon, Ron B.; Providência, Rui; Khan, Fakhar Z.; Segal, Oliver R.; Babu, Girish G.; Bradley, Richard; Rowland, Edward; Ahsan, Syed; Chow, Anthony W.; Lowe, Martin D.; Taggart, Peter

2016-01-01

The spatial variation in restitution properties in relation to varying stimulus site is poorly defined. This study aimed to investigate the effect of varying stimulus site on apicobasal and transmural activation time (AT), action potential duration (APD) and repolarization time (RT) during restitution studies in the intact human heart. Ten patients with structurally normal hearts, undergoing clinical electrophysiology studies, were enrolled. Decapolar catheters were placed apex to base in the endocardial right ventricle (RVendo) and left ventricle (LVendo), and an LV branch of the coronary sinus (LVepi) for transmural recording. S1–S2 restitution protocols were performed pacing RVendo apex, LVendo base, and LVepi base. Overall, 725 restitution curves were analyzed, 74% of slopes had a maximum slope of activation recovery interval (ARI) restitution (Smax) > 1 (P < 0.001); mean Smax = 1.76. APD was shorter in the LVepi compared with LVendo, regardless of pacing site (30-ms difference during RVendo pacing, 25-ms during LVendo, and 48-ms during LVepi; 50th quantile, P < 0.01). Basal LVepi pacing resulted in a significant transmural gradient of RT (77 ms, 50th quantile: P < 0.01), due to loss of negative transmural AT-APD coupling (mean slope 0.63 ± 0.3). No significant transmural gradient in RT was demonstrated during endocardial RV or LV pacing, with preserved negative transmural AT-APD coupling (mean slope −1.36 ± 1.9 and −0.71 ± 0.4, respectively). Steep ARI restitution slopes predominate in the normal ventricle and dynamic ARI; RT gradients exist that are modulated by the site of activation. Epicardial stimulation to initiate ventricular activation promotes significant transmural gradients of repolarization that could be proarrhythmic. PMID:27371682

Negative Emotion Does Not Modulate Rapid Feature Integration Effects

PubMed Central

Trübutschek, Darinka; Egner, Tobias

2012-01-01

Emotional arousal at encoding is known to facilitate later memory recall. In the present study, we asked whether this emotion-modulation of episodic memory is also evident at very short time scales, as measured by “feature integration effects,” the moment-by-moment binding of relevant stimulus and response features in episodic memory. This question was motivated by recent findings that negative emotion appears to potentiate first-order trial sequence effects in classic conflict tasks, which has been attributed to emotion-modulation of conflict-driven cognitive control processes. However, these effects could equally well have been carried by emotion-modulation of mnemonic feature binding processes, which were perfectly confounded with putative control processes in these studies. In the present experiments, we tried to shed light on this question by testing explicitly whether feature integration processes, assessed in isolation of conflict–control, are in fact susceptible to negative emotion-modulation. For this purpose, we adopted a standard protocol for assessing the rapid binding of stimulus and response features in episodic memory (Experiment 1) and paired it with the presentation of either neutral or fearful background face stimuli, shown either at encoding only (Experiment 2), or at both encoding and retrieval (Experiment 3). Whereas reliable feature integration effects were observed in all three experiments, no evidence for emotion-modulation of these effects was detected, in spite of significant effects of emotion on response times. These findings suggest that rapid feature integration of foreground stimulus and response features is not subject to modulation by negative emotional background stimuli and further suggest that previous reports of emotion-modulated trial–transition effects are likely attributable to the effects of emotion on cognitive control processes. PMID:22509172

Waning of "conditioned pain modulation": a novel expression of subtle pronociception in migraine.

PubMed

Nahman-Averbuch, Hadas; Granovsky, Yelena; Coghill, Robert C; Yarnitsky, David; Sprecher, Elliot; Weissman-Fogel, Irit

2013-01-01

To assess the decay of the conditioned pain modulation (CPM) response along repeated applications as a possible expression of subtle pronociception in migraine. One of the most explored mechanisms underlying the pain modulation system is "diffuse noxious inhibitory controls," which is measured psychophysically in the lab by the CPM paradigm. There are contradicting reports on CPM response in migraine, questioning whether migraineurs express pronociceptive pain modulation. Migraineurs (n = 26) and healthy controls (n = 35), all females, underwent 3 stimulation series, consisting of repeated (1) "test-stimulus" (Ts) alone that was given first followed by (2) parallel CPM application (CPM-parallel), and (3) sequential CPM application (CPM-sequential), in which the Ts is delivered during or following the conditioning-stimulus, respectively. In all series, the Ts repeated 4 times (0-3). In the CPM series, repetition "0" consisted of the Ts-alone that was followed by 3 repetitions of the Ts with a conditioning-stimulus application. Although there was no difference between migraineurs and controls for the first CPM response in each series, we found waning of CPM-parallel efficiency along the series for migraineurs (P = .005 for third vs first CPM), but not for controls. Further, greater CPM waning in the CPM-sequential series was correlated with less reported extent of pain reduction by episodic medication (r = 0.493, P = .028). Migraineurs have subtle deficits in endogenous pain modulation which requires a more challenging test protocol than the commonly used single CPM. Waning of CPM response seems to reveal this pronociceptive state. The clinical relevance of the CPM waning effect is highlighted by its association with clinical parameters of migraine. © 2013 American Headache Society.

Disruption of Cue-Potentiated Feeding in Mice with Blocked Ghrelin Signaling

PubMed Central

Walker, Angela K.; Ibia, Imikomobong E.; Zigman, Jeffrey M.

2012-01-01

The peptide hormone ghrelin regulates a variety of eating behaviors. Not only does it potently increase intake of freely-available food, but it also shifts food preference towards diets rich in fat, enhances operant responding for food rewards, and induces conditioned place preference for food rewards. Here, we postulated that ghrelin also enables cue-potentiated feeding, in which eating is enhanced upon presentation of a food-conditioned stimulus. To test this hypothesis, a novel cue-potentiated feeding protocol adapted for use in mice was designed and validated, and then the effects of pharmacologic ghrelin receptor (GHSR) antagonism and GHSR transcriptional blockade (as occurs in GHSR-null mice) were assessed. Sated C57BL/6J mice indeed demonstrated cue-potentiated intake of grain-based pellets specifically upon presentation of a positive conditioned stimulus (CS+) but not a negative conditioned stimulus (CS-). Treatment with a GHSR antagonist blocked potentiated feeding in sated C57BL/6J mice in response to the CS+. In contrast, while GHSR-null mice also lacked a potentiation of feeding specifically in response to the CS+, they displayed an enhanced intake of pellets in response to both the positive and negative conditioned stimuli. The pattern of immediate early gene expression within the basolateral amygdala -- a brain region previously linked to cue-potentiated feeding -- paralleled the observed behavior of these mice, suggesting uncharacteristic activation of the amygdala in response to negative conditioned stimuli in GHSR-null mice as compared to wild-type littermates. Thus, although the observed disruptions in cue-potentiated feeding are different depending upon whether GHSR activity or GHSR expression is blocked, a key role for GHSRs in establishing a specific positive cue-food association has now been established. PMID:23063723

COMT and DRD2/ANKK-1 gene-gene interaction account for resetting of gamma neural oscillations to auditory stimulus-driven attention.

PubMed

Garcia-Garcia, Manuel; Via, Marc; Zarnowiec, Katarzyna; SanMiguel, Iria; Escera, Carles; Clemente, Immaculada C

2017-01-01

Attention capture by potentially relevant environmental stimuli is critical for human survival, yet it varies considerably among individuals. A large series of studies has suggested that attention capture may depend on the cognitive balance between maintenance and manipulation of mental representations and the flexible switch between goal-directed representations and potentially relevant stimuli outside the focus of attention; a balance that seems modulated by a prefrontostriatal dopamine pathway. Here, we examined inter-individual differences in the cognitive control of attention through studying the effects of two single nucleotide polymorphisms regulating dopamine at the prefrontal cortex and the striatum (i.e., COMTMet108/158Val and ANKK1/DRD2TaqIA) on stimulus-driven attention capture. Healthy adult participants (N = 40) were assigned to different groups according to the combination of the polymorphisms COMTMet108/158Val and ANKK1/DRD2TaqIA, and were instructed to perform on a well-established distraction protocol. Performance in individuals with a balance between prefrontal dopamine display and striatal receptor density was slowed down by the occurrence of unexpected distracting events, while those with a rather unbalanced dopamine activity were able maintain task performance with no time delay, yet at the expense of a slightly lower accuracy. This advantage, associated to their distinct genetic profiles, was paralleled by an electrophysiological mechanism of phase-resetting of gamma neural oscillation to the novel, distracting events. Taken together, the current results suggest that the epistatic interaction between COMTVal108/158Met and ANKK1/DRD2 TaqIa genetic polymorphisms lies at the basis of stimulus-driven attention capture.

Quantifying stimulus-response rehabilitation protocols by auditory feedback in Parkinson's disease gait pattern

NASA Astrophysics Data System (ADS)

Pineda, Gustavo; Atehortúa, Angélica; Iregui, Marcela; García-Arteaga, Juan D.; Romero, Eduardo

2017-11-01

External auditory cues stimulate motor related areas of the brain, activating motor ways parallel to the basal ganglia circuits and providing a temporary pattern for gait. In effect, patients may re-learn motor skills mediated by compensatory neuroplasticity mechanisms. However, long term functional gains are dependent on the nature of the pathology, follow-up is usually limited and reinforcement by healthcare professionals is crucial. Aiming to cope with these challenges, several researches and device implementations provide auditory or visual stimulation to improve Parkinsonian gait pattern, inside and outside clinical scenarios. The current work presents a semiautomated strategy for spatio-temporal feature extraction to study the relations between auditory temporal stimulation and spatiotemporal gait response. A protocol for auditory stimulation was built to evaluate the integrability of the strategy in the clinic practice. The method was evaluated in transversal measurement with an exploratory group of people with Parkinson's (n = 12 in stage 1, 2 and 3) and control subjects (n =6). The result showed a strong linear relation between auditory stimulation and cadence response in control subjects (R=0.98 +/-0.008) and PD subject in stage 2 (R=0.95 +/-0.03) and stage 3 (R=0.89 +/-0.05). Normalized step length showed a variable response between low and high gait velocity (0.2> R >0.97). The correlation between normalized mean velocity and stimulus was strong in all PD stage 2 (R>0.96) PD stage 3 (R>0.84) and controls (R>0.91) for all experimental conditions. Among participants, the largest variation from baseline was found in PD subject in stage 3 (53.61 +/-39.2 step/min, 0.12 +/- 0.06 in step length and 0.33 +/- 0.16 in mean velocity). In this group these values were higher than the own baseline. These variations are related with direct effect of metronome frequency on cadence and velocity. The variation of step length involves different regulation strategies and could need others specific external cues. In conclusion the current protocol (and their selected parameters, kind of sound time for training, step of variation, range of variation) provide a suitable gait facilitation method specially for patients with the highest gait disturbance (stage 2 and 3). The method should be adjusted for initial stages and evaluated in a rehabilitation program.

Anaerobic threshold employed on exercise training prescription and performance assessment for laboratory rodents: A short review.

PubMed

Abreu, Phablo; Mendes, Sávio Victor Diogenes; Leal-Cardoso, José Henrique; Ceccatto, Vânia Marilande

2016-04-15

Several studies have generated numerous terms in the field of exercise training prescription and performance assessment that often do not match the information previously demonstrated by many other works, generating much debate and resulting in an immense pool of scientific results. Several protocols in exercise training prescription and performance assessment have been proposed for these purposes by many reasons. In the field of exercise science, the protocol must be thoroughly investigated and provide real tools to be reproducible. Many laboratories have been adapting and developing evaluation protocols and testing on physical training of rodents in different experimental conditions. In this context, mice, rats and rabbits are preferentially chosen due to easy manipulation and good response to exercise, and comparable at results obtained with humans in compatible effort intensities. But, the exercise training programs and aerobic-anaerobic transition assessment proposed for animal models vary extensively, depending on the species, gender, age, type of stimulus, type of exercise, type of method and also on the specific objectives of the program. This short review demonstrates the need in offering tools performed by invasive measurement to assess the anaerobic threshold by blood lactate employed on evolution of aerobic-anaerobic parameters of rodents. The objective of this short review was to present and to discuss physical evaluation protocols applications to rodents. The table submitted may give a basis for anaerobic threshold employed on exercise training prescription and performance assessment for laboratory rodents in future research. Copyright © 2016 Elsevier Inc. All rights reserved.

In vivo evaluation of the effect of stimulus distribution on FIR statistical efficiency in event-related fMRI.

PubMed

Jansma, J Martijn; de Zwart, Jacco A; van Gelderen, Peter; Duyn, Jeff H; Drevets, Wayne C; Furey, Maura L

2013-05-15

Technical developments in MRI have improved signal to noise, allowing use of analysis methods such as Finite impulse response (FIR) of rapid event related functional MRI (er-fMRI). FIR is one of the most informative analysis methods as it determines onset and full shape of the hemodynamic response function (HRF) without any a priori assumptions. FIR is however vulnerable to multicollinearity, which is directly related to the distribution of stimuli over time. Efficiency can be optimized by simplifying a design, and restricting stimuli distribution to specific sequences, while more design flexibility necessarily reduces efficiency. However, the actual effect of efficiency on fMRI results has never been tested in vivo. Thus, it is currently difficult to make an informed choice between protocol flexibility and statistical efficiency. The main goal of this study was to assign concrete fMRI signal to noise values to the abstract scale of FIR statistical efficiency. Ten subjects repeated a perception task with five random and m-sequence based protocol, with varying but, according to literature, acceptable levels of multicollinearity. Results indicated substantial differences in signal standard deviation, while the level was a function of multicollinearity. Experiment protocols varied up to 55.4% in standard deviation. Results confirm that quality of fMRI in an FIR analysis can significantly and substantially vary with statistical efficiency. Our in vivo measurements can be used to aid in making an informed decision between freedom in protocol design and statistical efficiency. Published by Elsevier B.V.

Continuous-Variable Measurement-Device-Independent Multipartite Quantum Communication Using Coherent States

NASA Astrophysics Data System (ADS)

Zhou, Jian; Guo, Ying

2017-02-01

A continuous-variable measurement-device-independent (CV-MDI) multipartite quantum communication protocol is designed to realize multipartite communication based on the GHZ state analysis using Gaussian coherent states. It can remove detector side attack as the multi-mode measurement is blindly done in a suitable Black Box. The entanglement-based CV-MDI multipartite communication scheme and the equivalent prepare-and-measurement scheme are proposed to analyze the security and guide experiment, respectively. The general eavesdropping and coherent attack are considered for the security analysis. Subsequently, all the attacks are ascribed to coherent attack against imperfect links. The asymptotic key rate of the asymmetric configuration is also derived with the numeric simulations illustrating the performance of the proposed protocol.

Transfer of function and prior derived-relations testing.

PubMed

Doughty, Adam H; Best, Lauren

2017-10-01

This experiment assessed transfer of function through equivalence relations with and without prior derived-stimulus-relations (DSR) testing. In a DSR-Testing Group, eight college students learned A-B and A-C discriminations in baseline. They then derived the B-C and C-B equivalence relations before being exposed to a transfer-of-function manipulation and test. Eight participants in a No-DSR Testing Group were exposed to the transfer-of-function manipulation and test immediately after learning the baseline discriminations (i.e., B-C and C-B testing were omitted). In the transfer-of-function manipulation, participants learned to respond differently in the presence of B1 and B2 to avoid money loss. In the transfer-of-function test, responding in the presence of C1 and C2 was measured in the absence of differential consequences. Transfer of function occurred reliably only in the DSR-Testing Group (i.e., participants responding to C1 and C2 in the manner they learned to respond to B1 and B2, respectively). These findings support the notion that prior DSR testing can be critical to observing transfer of function. Copyright © 2017 Elsevier B.V. All rights reserved.

Hair cell tufts and afferent innervation of the bullfrog crista ampullaris

NASA Technical Reports Server (NTRS)

Myers, Steven F.; Lewis, Edwin R.

1990-01-01

Within the bullfrog semicircular canal crista, hair cell tuft types were defined and mapped with the aid of scanning electron microscopy. Dye-filled planar afferent axons had mean distal axonal diameters of 1.6-4.9 microns, highly branched arbors, and contacted 11-24 hair cells. Dye-filled isthmus afferent axons had mean distal axonal diameters of 1.8-7.9 microns, with either small or large field arbors contacting 4-9 or 25-31 hair cells. The estimated mean number of contacts per innervated hair cell was 2.2 for planar and 1.3 for isthmus afferent neurons. Data on evoked afferent responses were available only for isthmus units that were observed to respond to our microrotational stimuli. Of 21 such afferent neurons, eight were successfully dye-filled. Within this sample, high-gain units had large field arbors and lower-gain units had small field arbors. The sensitivity of each afferent neuron was analyzed in terms of noise equivalent input (NEI), the stimulus amplitude for which the afferent response amplitude is just equivalent to the rms deviation of the instantaneous spike rate. NEI for isthmus units varied from 0.63 to 8.2 deg/s; the mean was 3.2 deg/s.

A behavior analytic analogue of learning to use synonyms, syntax, and parts of speech.

PubMed

Chase, Philip N; Ellenwood, David W; Madden, Gregory

2008-01-01

Matching-to-sample and sequence training procedures were used to develop responding to stimulus classes that were considered analogous to 3 aspects of verbal behavior: identifying synonyms and parts of speech, and using syntax. Matching-to-sample procedures were used to train 12 paired associates from among 24 stimuli. These pairs were analogous to synonyms. Then, sequence characteristics were trained to 6 of the stimuli. The result was the formation of 3 classes of 4 stimuli, with the classes controlling a sequence response analogous to a simple ordering syntax: first, second, and third. Matching-to-sample procedures were then used to add 4 stimuli to each class. These stimuli, without explicit sequence training, also began to control the same sequence responding as the other members of their class. Thus, three 8-member functionally equivalent sequence classes were formed. These classes were considered to be analogous to parts of speech. Further testing revealed three 8-member equivalence classes and 512 different sequences of first, second, and third. The study indicated that behavior analytic procedures may be used to produce some generative aspects of verbal behavior related to simple syntax and semantics.

Slow Temporal Summation of Pain for Assessment of Central Pain Sensitivity and Clinical Pain of Fibromyalgia Patients

PubMed Central

Staud, Roland; Weyl, Elizabeth E.; Riley, Joseph L.; Fillingim, Roger B.

2014-01-01

Background In healthy individuals slow temporal summation of pain or wind-up (WU) can be evoked by repetitive heat-pulses at frequencies of ≥.33 Hz. Previous WU studies have used various stimulus frequencies and intensities to characterize central sensitization of human subjects including fibromyalgia (FM) patients. However, many trials demonstrated considerable WU-variability including zero WU or even wind-down (WD) at stimulus intensities sufficient for activating C-nociceptors. Additionally, few WU-protocols have controlled for contributions of individual pain sensitivity to WU-magnitude, which is critical for WU-comparisons. We hypothesized that integration of 3 different WU-trains into a single WU-response function (WU-RF) would not only control for individuals’ pain sensitivity but also better characterize their central pain responding including WU and WD. Methods 33 normal controls (NC) and 38 FM patients participated in a study of heat-WU. We systematically varied stimulus intensities of.4 Hz heat-pulse trains applied to the hands. Pain summation was calculated as difference scores of 1st and 5th heat-pulse ratings. WU-difference (WU-Δ) scores related to 3 heat-pulse trains (44°C, 46°C, 48°C) were integrated into WU-response functions whose slopes were used to assess group differences in central pain sensitivity. WU-aftersensations (WU-AS) at 15 s and 30 s were used to predict clinical FM pain intensity. Results WU-Δ scores linearly accelerated with increasing stimulus intensity (p<.001) in both groups of subjects (FM>NC) from WD to WU. Slope of WU-RF, which is representative of central pain sensitivity, was significantly steeper in FM patients than NC (p<.003). WU-AS predicted clinical FM pain intensity (Pearson’s r = .4; p<.04). Conclusions Compared to single WU series, WU-RFs integrate individuals’ pain sensitivity as well as WU and WD. Slope of WU-RFs was significantly different between FM patients and NC. Therefore WU-RF may be useful for assessing central sensitization of chronic pain patients in research and clinical practice. PMID:24558475

In-Fiber Magneto-Optic Devices Based on Ultrahigh Verdet Constant Organic Materials and Holey Fibers

DTIC Science & Technology

2009-02-02

protocols and a noise equivalent magnetic field sensitivity of ~ 100 pT/ VHz has been demonstrated. • Magneto-optic properties of magnetite - PMMA composite...nanoparticle - PMMA nanocomposite. We have used both transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) to...we expect to enhance it in our devices by their proper symmetrization as described above. Passive Poking core ^^ direction Magnetic AA

In vivo imaging and analysis of cerebrovascular hemodynamic responses and tissue oxygenation in the mouse brain.

PubMed

Kisler, Kassandra; Lazic, Divna; Sweeney, Melanie D; Plunkett, Shane; El Khatib, Mirna; Vinogradov, Sergei A; Boas, David A; Sakadži, Sava; Zlokovic, Berislav V

2018-06-01

Cerebrovascular dysfunction has an important role in the pathogenesis of multiple brain disorders. Measurement of hemodynamic responses in vivo can be challenging, particularly as techniques are often not described in sufficient detail and vary between laboratories. We present a set of standardized in vivo protocols that describe high-resolution two-photon microscopy and intrinsic optical signal (IOS) imaging to evaluate capillary and arteriolar responses to a stimulus, regional hemodynamic responses, and oxygen delivery to the brain. The protocol also describes how to measure intrinsic NADH fluorescence to understand how blood O 2 supply meets the metabolic demands of activated brain tissue, and to perform resting-state absolute oxygen partial pressure (pO 2 ) measurements of brain tissue. These methods can detect cerebrovascular changes at far higher resolution than MRI techniques, although the optical nature of these techniques limits their achievable imaging depths. Each individual procedure requires 1-2 h to complete, with two to three procedures typically performed per animal at a time. These protocols are broadly applicable in studies of cerebrovascular function in healthy and diseased brain in any of the existing mouse models of neurological and vascular disorders. All these procedures can be accomplished by a competent graduate student or experienced technician, except the two-photon measurement of absolute pO 2 level, which is better suited to a more experienced, postdoctoral-level researcher.

PubMed Central

Bédard, S; Desrochers, A; Fecteau, G; Higgins, R

2001-01-01

This study was designed to evaluate 4 preoperative skin preparations, that is, more specifically, to compare the efficacy of chlorhexidine gluconate (CG) and povidone-iodine (PI), as well as 2 hair removal techniques (clipper alone or clipper followed by razor) for preoperative skin preparation in cattle. The 4 protocols resulted in a significant decrease in the number of bacterial colony-forming units (cfu). Group 4 (clipping + shaving + CG) had a significantly lower number of preoperative cfu per gel plate compared with groups 1 (clipping + PI) and 3 (clipping + shaving + PI). Skin reaction frequency was significantly higher in groups 3 and 4 (47.8% for both protocols) than in groups 1 and 2 (clipping + PI or CG) (8.7% for both). Wound infection frequency was 4.3% (4/92) and no significant difference was observed between the 4 treatment groups. The 4 protocols tested were equivalent as to efficacy and satisfactorily decreased skin microflora. Clipping alone was shown to be preferable to clipping plus shaving as a method of hair removal in cattle, with fewer skin reactions and no more wound infections. PMID:11265188

Intra and inter-session reliability of rapid Transcranial Magnetic Stimulation stimulus-response curves of tibialis anterior muscle in healthy older adults.

PubMed

Peri, Elisabetta; Ambrosini, Emilia; Colombo, Vera Maria; van de Ruit, Mark; Grey, Michael J; Monticone, Marco; Ferriero, Giorgio; Pedrocchi, Alessandra; Ferrigno, Giancarlo; Ferrante, Simona

2017-01-01

The clinical use of Transcranial Magnetic Stimulation (TMS) as a technique to assess corticospinal excitability is limited by the time for data acquisition and the measurement variability. This study aimed at evaluating the reliability of Stimulus-Response (SR) curves acquired with a recently proposed rapid protocol on tibialis anterior muscle of healthy older adults. Twenty-four neurologically-intact adults (age:55-75 years) were recruited for this test-retest study. During each session, six SR curves, 3 at rest and 3 during isometric muscle contractions at 5% of maximum voluntary contraction (MVC), were acquired. Motor Evoked Potentials (MEPs) were normalized to the maximum peripherally evoked response; the coil position and orientation were monitored with an optical tracking system. Intra- and inter-session reliability of motor threshold (MT), area under the curve (AURC), MEPmax, stimulation intensity at which the MEP is mid-way between MEPmax and MEPmin (I50), slope in I50, MEP latency, and silent period (SP) were assessed in terms of Standard Error of Measurement (SEM), relative SEM, Minimum Detectable Change (MDC), and Intraclass Correlation Coefficient (ICC). The relative SEM was ≤10% for MT, I50, latency and SP both at rest and 5%MVC, while it ranged between 11% and 37% for AURC, MEPmax, and slope. MDC values were overall quite large; e.g., MT required a change of 12%MSO at rest and 10%MSO at 5%MVC to be considered a real change. Inter-sessions ICC were >0.6 for all measures but slope at rest and MEPmax and latency at 5%MVC. Measures derived from SR curves acquired in <4 minutes are affected by similar measurement errors to those found with long-lasting protocols, suggesting that the rapid method is at least as reliable as the traditional methods. As specifically designed to include older adults, this study provides normative data for future studies involving older neurological patients (e.g. stroke survivors).

Nanomolar Oxytocin Synergizes with Weak Electrical Afferent Stimulation to Activate the Locomotor CPG of the Rat Spinal Cord In Vitro

PubMed Central

Dose, Francesco; Zanon, Patrizia; Coslovich, Tamara; Taccola, Giuliano

2014-01-01

Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM–1 μM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other protocols, and delineate the use of oxytocin to strengthen the efficiency of electrical stimulation to activate locomotor circuits. PMID:24658101

Alouatta trichromatic color vision: cone spectra and physiological responses studied with microspectrophotometry and single unit retinal electrophysiology.

PubMed

Silveira, Luiz Carlos L; Saito, Cézar A; da Silva Filho, Manoel; Kremers, Jan; Bowmaker, James K; Lee, Barry B

2014-01-01

The howler monkeys (Alouatta sp.) are the only New World primates to exhibit routine trichromacy. Both males and females have three cone photopigments. However, in contrast to Old World monkeys, Alouatta has a locus control region upstream of each opsin gene on the X-chromosome and this might influence the retinal organization underlying its color vision. Post-mortem microspectrophotometry (MSP) was performed on the retinae of two male Alouatta to obtain rod and cone spectral sensitivities. The MSP data were consistent with only a single opsin being expressed in each cone and electrophysiological data were consistent with this primate expressing full trichromacy. To study the physiological organization of the retina underlying Alouatta trichromacy, we recorded from retinal ganglion cells of the same animals used for MSP measurements with a variety of achromatic and chromatic stimulus protocols. We found MC cells and PC cells in the Alouatta retina with similar properties to those previously found in the retina of other trichromatic primates. MC cells showed strong phasic responses to luminance changes and little response to chromatic pulses. PC cells showed strong tonic response to chromatic changes and small tonic response to luminance changes. Responses to other stimulus protocols (flicker photometry; changing the relative phase of red and green modulated lights; temporal modulation transfer functions) were also similar to those recorded in other trichromatic primates. MC cells also showed a pronounced frequency double response to chromatic modulation, and with luminance modulation response saturation accompanied by a phase advance between 10-20 Hz, characteristic of a contrast gain mechanism. This indicates a very similar retinal organization to Old-World monkeys. Cone-specific opsin expression in the presence of a locus control region for each opsin may call into question the hypothesis that this region exclusively controls opsin expression.

Fast-track surgery for uncomplicated appendicitis in children: a matched case-control study.

PubMed

Cundy, Thomas P; Sierakowski, Kyra; Manna, Alexandra; Cooper, Celia M; Burgoyne, Laura L; Khurana, Sanjeev

2017-04-01

Standardized post-operative protocols reduce variation and enhance efficiency in patient care. Patients may benefit from these initiatives by improved quality of care. This matched case-control study investigates the effect of a multidisciplinary criteria-led discharge protocol for uncomplicated appendicitis in children. Key protocol components included limiting post-operative antibiotics to two intravenous doses, avoidance of intravenous opioid analgesia, prompt resumption of diet, active encouragement of early ambulation and nursing staff autonomy to discharge patients that met assigned criteria. The study period was from August 2015 to February 2016. Outcomes were compared with a historical control group matched for operative approach. Outcomes for 83 patients enrolled to our protocol were compared with those of 83 controls. There was a 29.2% reduction in median post-operative length of stay in our protocol-based care group (19.6 versus 27.7 h; P < 0.001). The rate of discharges within 24 h improved from 12 to 42%. There was no significant difference in complication rate (4.8 versus 7.2%; P = 0.51). Mean oral morphine dose equivalent per kilogram requirement was less than half (46%) that of control group patients (P < 0.001). Mean number of ondansetron doses was also significantly lower. Projected annual direct cost savings following protocol implementation was AUD$77 057. Implementation of a criteria-led discharge protocol at our hospital decreased length of stay, reduced variation in care, preserved existing low morbidity, incurred substantial cost savings, and safely rationalized opioid and antiemetic medication. These protocols are inexpensive and offer tangible benefits that are accessible to all health care settings. © 2016 Royal Australasian College of Surgeons.

Accuracy of software-assisted detection of tumour feeders in transcatheter hepatic chemoembolization using three target definition protocols.

PubMed

Iwazawa, J; Ohue, S; Hashimoto, N; Mitani, T

2014-02-01

To compare the accuracy of computer software analysis using three different target-definition protocols to detect tumour feeder vessels for transarterial chemoembolization of hepatocellular carcinoma. C-arm computed tomography (CT) data were analysed for 81 tumours from 57 patients who had undergone chemoembolization using software-assisted detection of tumour feeders. Small, medium, and large-sized targets were manually defined for each tumour. The tumour feeder was verified when the target tumour was enhanced on selective C-arm CT of the investigated vessel during chemoembolization. The sensitivity, specificity, and accuracy of the three protocols were evaluated and compared. One hundred and eight feeder vessels supplying 81 lesions were detected. The sensitivity of the small, medium, and large target protocols was 79.8%, 91.7%, and 96.3%, respectively; specificity was 95%, 88%, and 50%, respectively; and accuracy was 87.5%, 89.9%, and 74%, respectively. The sensitivity was significantly higher for the medium (p = 0.003) and large (p < 0.001) target protocols than for the small target protocol. The specificity and accuracy were higher for the small (p < 0.001 and p < 0.001, respectively) and medium (p < 0.001 and p < 0.001, respectively) target protocols than for the large target protocol. The overall accuracy of software-assisted automated feeder analysis in transarterial chemoembolization for hepatocellular carcinoma is affected by the target definition size. A large target definition increases sensitivity and decreases specificity in detecting tumour feeders. A target size equivalent to the tumour size most accurately predicts tumour feeders. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Reproducibility of three-dimensional cephalometric landmarks in cone-beam and low-dose computed tomography.

PubMed

Olszewski, R; Frison, L; Wisniewski, M; Denis, J M; Vynckier, S; Cosnard, G; Zech, F; Reychler, H

2013-01-01

The purpose of this study is to compare the reproducibility of three-dimensional cephalometric landmarks on three-dimensional computed tomography (3D-CT) surface rendering using clinical protocols based on low-dose (35-mAs) spiral CT and cone-beam CT (I-CAT). The absorbed dose levels for radiosensitive organs in the maxillofacial region during exposure in both 3D-CT protocols were also assessed. The study population consisted of ten human dry skulls examined with low-dose CT and cone-beam CT. Two independent observers identified 24 cephalometric anatomic landmarks at 13 sites on the 3D-CT surface renderings using both protocols, with each observer repeating the identification 1 month later. A total of 1,920 imaging measurements were performed. Thermoluminescent dosimeters were placed at six sites around the thyroid gland, the submandibular glands, and the eyes in an Alderson phantom to measure the absorbed dose levels. When comparing low-dose CT and cone-beam CT protocols, the cone-beam CT protocol proved to be significantly more reproducible for four of the 13 anatomical sites. There was no significant difference between the protocols for the other nine anatomical sites. Both low-dose and cone-beam CT protocols were equivalent in dose absorption to the eyes and submandibular glands. However, thyroid glands were more irradiated with low-dose CT. Cone-beam CT was more reproducible and procured less irradiation to the thyroid gland than low-dose CT. Cone-beam CT should be preferred over low-dose CT for developing three-dimensional bony cephalometric analyses.

Dissociation of learned helplessness and fear conditioning in mice: a mouse model of depression.

PubMed

Landgraf, Dominic; Long, Jaimie; Der-Avakian, Andre; Streets, Margo; Welsh, David K

2015-01-01

The state of being helpless is regarded as a central aspect of depression, and therefore the learned helplessness paradigm in rodents is commonly used as an animal model of depression. The term 'learned helplessness' refers to a deficit in escaping from an aversive situation after an animal is exposed to uncontrollable stress specifically, with a control/comparison group having been exposed to an equivalent amount of controllable stress. A key feature of learned helplessness is the transferability of helplessness to different situations, a phenomenon called 'trans-situationality'. However, most studies in mice use learned helplessness protocols in which training and testing occur in the same environment and with the same type of stressor. Consequently, failures to escape may reflect conditioned fear of a particular environment, not a general change of the helpless state of an animal. For mice, there is no established learned helplessness protocol that includes the trans-situationality feature. Here we describe a simple and reliable learned helplessness protocol for mice, in which training and testing are carried out in different environments and with different types of stressors. We show that with our protocol approximately 50% of mice develop learned helplessness that is not attributable to fear conditioning.

A method for closed-loop presentation of sensory stimuli conditional on the internal brain-state of awake animals

PubMed Central

Rutishauser, Ueli; Kotowicz, Andreas; Laurent, Gilles

2013-01-01

Brain activity often consists of interactions between internal—or on-going—and external—or sensory—activity streams, resulting in complex, distributed patterns of neural activity. Investigation of such interactions could benefit from closed-loop experimental protocols in which one stream can be controlled depending on the state of the other. We describe here methods to present rapid and precisely timed visual stimuli to awake animals, conditional on features of the animal’s on-going brain state; those features are the presence, power and phase of oscillations in local field potentials (LFP). The system can process up to 64 channels in real time. We quantified its performance using simulations, synthetic data and animal experiments (chronic recordings in the dorsal cortex of awake turtles). The delay from detection of an oscillation to the onset of a visual stimulus on an LCD screen was 47.5 ms and visual-stimulus onset could be locked to the phase of ongoing oscillations at any frequency ≤40 Hz. Our software’s architecture is flexible, allowing on-the-fly modifications by experimenters and the addition of new closed-loop control and analysis components through plugins. The source code of our system “StimOMatic” is available freely as open-source. PMID:23473800

A Functional Magnetic Resonance Imaging Assessment of Small Animals’ Phobia Using Virtual Reality as a Stimulus

PubMed Central

Rey, Beatriz; Rodriguez-Pujadas, Aina; Breton-Lopez, Juani; Barros-Loscertales, Alfonso; Baños, Rosa M; Botella, Cristina; Alcañiz, Mariano; Avila, Cesar

2014-01-01

Background To date, still images or videos of real animals have been used in functional magnetic resonance imaging protocols to evaluate the brain activations associated with small animals’ phobia. Objective The objective of our study was to evaluate the brain activations associated with small animals’ phobia through the use of virtual environments. This context will have the added benefit of allowing the subject to move and interact with the environment, giving the subject the illusion of being there. Methods We have analyzed the brain activation in a group of phobic people while they navigated in a virtual environment that included the small animals that were the object of their phobia. Results We have found brain activation mainly in the left occipital inferior lobe (P<.05 corrected, cluster size=36), related to the enhanced visual attention to the phobic stimuli; and in the superior frontal gyrus (P<.005 uncorrected, cluster size=13), which is an area that has been previously related to the feeling of self-awareness. Conclusions In our opinion, these results demonstrate that virtual stimulus can enhance brain activations consistent with previous studies with still images, but in an environment closer to the real situation the subject would face in their daily lives. PMID:25654753

Predicting Return of Fear Following Exposure Therapy With an Implicit Measure of Attitudes

PubMed Central

Vasey, Michael W.; Harbaugh, Casaundra N.; Buffington, Adam G.; Jones, Christopher R.; Fazio, Russell H.

2012-01-01

We sought to advance understanding of the processes underlying the efficacy of exposure therapy and particularly the phenomenon of return of fear (ROF) following treatment by drawing on a social psychological view of phobias as attitudes. Specifically, a dual process theory of attitude-related behavior predicts that a positive response to exposure therapy may reflect change in either the automatic (the attitude representation itself) or controlled (skills and confidence at coping with the fear) responses to the phobic stimulus, or both. However, if the attitude representation remains negative following treatment, ROF should be more likely. We tested this hypothesis in a clinical sample of individuals with public speaking phobia using a single-session exposure therapy protocol previously shown to be efficacious but also associated with some ROF. Consistent with predictions, a post-treatment implicit measure of attitudes toward public speaking (the Personalized Implicit Association Test [PIAT]) predicted ROF at 1-month follow-up. These results suggest that change in the automatically activated attitude toward the phobic stimulus is an important goal of exposure therapy and that an implicit measure like the PIAT can provide a useful measure of such change by which to gauge the adequacy of exposure treatment and predict its long-term efficacy. PMID:23085186

Impact of early life adversity on EMG stress reactivity of the trapezius muscle.

PubMed

Luijcks, Rosan; Vossen, Catherine J; Roggeveen, Suzanne; van Os, Jim; Hermens, Hermie J; Lousberg, Richel

2016-09-01

Human and animal research indicates that exposure to early life adversity increases stress sensitivity later in life. While behavioral markers of adversity-induced stress sensitivity have been suggested, physiological markers remain to be elucidated. It is known that trapezius muscle activity increases during stressful situations. The present study examined to what degree early life adverse events experienced during early childhood (0-11 years) and adolescence (12-17 years) moderate experimentally induced electromyographic (EMG) stress activity of the trapezius muscles, in an experimental setting. In a general population sample (n = 115), an anticipatory stress effect was generated by presenting a single unpredictable and uncontrollable electrical painful stimulus at t = 3 minutes. Subjects were unaware of the precise moment of stimulus delivery and its intensity level. Linear and nonlinear time courses in EMG activity were modeled using multilevel analysis. The study protocol included 2 experimental sessions (t = 0 and t = 6 months) allowing for examination of reliability.Results show that EMG stress reactivity during the stress paradigm was consistently stronger in people with higher levels of early life adverse events; early childhood adversity had a stronger moderating effect than adolescent adversity. The impact of early life adversity on EMG stress reactivity may represent a reliable facet that can be used in both clinical and nonclinical studies.

Making Decisions under Ambiguity: Judgment Bias Tasks for Assessing Emotional State in Animals

PubMed Central

Roelofs, Sanne; Boleij, Hetty; Nordquist, Rebecca E.; van der Staay, Franz Josef

2016-01-01

Judgment bias tasks (JBTs) are considered as a family of promising tools in the assessment of emotional states of animals. JBTs provide a cognitive measure of optimism and/or pessimism by recording behavioral responses to ambiguous stimuli. For instance, a negative emotional state is expected to produce a negative or pessimistic judgment of an ambiguous stimulus, whereas a positive emotional state produces a positive or optimistic judgment of the same ambiguous stimulus. Measuring an animal’s emotional state or mood is relevant in both animal welfare research and biomedical research. This is reflected in the increasing use of JBTs in both research areas. We discuss the different implementations of JBTs with animals, with a focus on their potential as an accurate measure of emotional state. JBTs have been successfully applied to a very broad range of species, using many different types of testing equipment and experimental protocols. However, further validation of this test is deemed necessary. For example, the often extensive training period required for successful judgment bias testing remains a possible factor confounding results. Also, the issue of ambiguous stimuli losing their ambiguity with repeated testing requires additional attention. Possible improvements are suggested to further develop the JBTs in both animal welfare and biomedical research. PMID:27375454

Electrically induced muscle cramps induce hypertrophy of calf muscles in healthy adults.

PubMed

Behringer, M; Moser, M; Montag, J; McCourt, M; Tenner, D; Mester, J

2015-06-01

Skeletal muscles usually cramp at short lengths, where the tension that can be exerted by muscle fibers is low. Since high tension is an important anabolic stimulus, it is questionable if cramps can induce hypertrophy and strength gains. In the present study we investigated if electrically induced cramps (EIMCs) can elicit these adaptations. 15 healthy male adults were randomly assigned to an intervention (IG; n=10) and a control group (CG; n=5). The cramp protocol (CP) applied twice a week to one leg of the IG, consisted of 3x6 EIMCs, of 5 s each. Calf muscles of the opposite leg were stimulated equally, but were hindered from cramping by fixating the ankle at 0° plantar flexion (nCP). After six weeks, the cross sectional area of the triceps surae was similarly increased in both the CP (+9.0±3.4%) and the nCP (+6.8±3.7%). By contrast, force of maximal voluntary contractions, measured at 0° and 30° plantar flexion, increased significantly only in nCP (0°: +8.5±8.8%; 30°: 11.7±13.7%). The present data indicate that muscle cramps can induce hypertrophy in calf muscles, though lacking high tension as an important anabolic stimulus.

Electrically induced muscle cramps induce hypertrophy of calf muscles in healthy adults

PubMed Central

Behringer, M.; Moser, M.; Montag, J.; McCourt, M.; Tenner, D.; Mester, J.

2015-01-01

Objectives: Skeletal muscles usually cramp at short lengths, where the tension that can be exerted by muscle fibers is low. Since high tension is an important anabolic stimulus, it is questionable if cramps can induce hypertrophy and strength gains. In the present study we investigated if electrically induced cramps (EIMCs) can elicit these adaptations. Methods: 15 healthy male adults were randomly assigned to an intervention (IG; n=10) and a control group (CG; n=5). The cramp protocol (CP) applied twice a week to one leg of the IG, consisted of 3x6 EIMCs, of 5 s each. Calf muscles of the opposite leg were stimulated equally, but were hindered from cramping by fixating the ankle at 0° plantar flexion (nCP). Results: After six weeks, the cross sectional area of the triceps surae was similarly increased in both the CP (+9.0±3.4%) and the nCP (+6.8±3.7%). By contrast, force of maximal voluntary contractions, measured at 0° and 30° plantar flexion, increased significantly only in nCP (0°: +8.5±8.8%; 30°: 11.7±13.7%). Conclusion: The present data indicate that muscle cramps can induce hypertrophy in calf muscles, though lacking high tension as an important anabolic stimulus. PMID:26032216

The effect of early-life stress on airway inflammation in adult mice.

PubMed

Vig, Rattanjeet; Gordon, John R; Thébaud, Bernard; Befus, A Dean; Vliagoftis, Harissios

2010-01-01

Neonatal stress induces permanent physiological changes that may influence the immune system. Early-life stress increases asthma disease severity in children. We investigated the effects of early-life stress on allergic airway inflammation using a murine model of asthma coupled to maternal separation as an early-life stress stimulus. Maternally separated (MS) and unseparated control (CON) mice were sensitized with ovalbumin (OVA) beginning at day 31 after birth. Challenging mice with OVA increased airway hyperresponsiveness (AHR) and the number of inflammatory cells recovered in the bronchoalveolar lavage (BAL), compared to saline-challenged mice. Challenging MS mice with OVA resulted in less total inflammatory cells, eosinophils, interferon-gamma, and interleukin-4 in BAL compared to CON mice. However, MS mice challenged with OVA exhibited AHR similar to CON mice challenged with OVA. In contrast, an enhanced stress protocol (MS+) involving removal of pups from their home cages following the removal of the dam resulted in inflammatory cell accumulation and cytokine levels in the BAL similar to CON mice and higher than MS mice. These findings indicate that the effect of early-life psychological factors on the development of airway inflammatory diseases such as asthma is very complex and depends on the quality of the psychological stress stimulus.

fMRI mapping of the visual system in the mouse brain with interleaved snapshot GE-EPI.

PubMed

Niranjan, Arun; Christie, Isabel N; Solomon, Samuel G; Wells, Jack A; Lythgoe, Mark F

2016-10-01

The use of functional magnetic resonance imaging (fMRI) in mice is increasingly prevalent, providing a means to non-invasively characterise functional abnormalities associated with genetic models of human diseases. The predominant stimulus used in task-based fMRI in the mouse is electrical stimulation of the paw. Task-based fMRI in mice using visual stimuli remains underexplored, despite visual stimuli being common in human fMRI studies. In this study, we map the mouse brain visual system with BOLD measurements at 9.4T using flashing light stimuli with medetomidine anaesthesia. BOLD responses were observed in the lateral geniculate nucleus, the superior colliculus and the primary visual area of the cortex, and were modulated by the flashing frequency, diffuse vs focussed light and stimulus context. Negative BOLD responses were measured in the visual cortex at 10Hz flashing frequency; but turned positive below 5Hz. In addition, the use of interleaved snapshot GE-EPI improved fMRI image quality without diminishing the temporal contrast-noise-ratio. Taken together, this work demonstrates a novel methodological protocol in which the mouse brain visual system can be non-invasively investigated using BOLD fMRI. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Influence of inter-stimulus interval of spinal cord stimulation in patients with disorders of consciousness: A preliminary functional near-infrared spectroscopy study.

PubMed

Zhang, Yujin; Yang, Yi; Si, Juanning; Xia, Xiaoyu; He, Jianghong; Jiang, Tianzi

2018-01-01

Spinal cord stimulation (SCS) is a promising treatment for disorders of consciousness (DOC), but the underlying mechanism and most effective procedures remain uncertain. To optimize the protocol, previous studies evaluated the frequency-specific effects of SCS on neurophysiological activities. However, whether and how the inter-stimulus interval (ISI) parameter affects the SCS neuromodulation in DOC remains unknown. We enrolled nine DOC patients who had implanted SCS devices and conducted three different durations of ISIs. Using functional near-infrared spectroscopy (fNIRS), we monitored the blood volume fluctuations in the prefrontal and occipital cortices during the SCS. The results showed that short stimuli (30 s) induced significant cerebral blood volume changes, especially in the prefrontal cortex, an important area in the consciousness system. By comparing the mean value of the responses from the first and the last block in each session, a shorter ISI was found to improve the blood volume in the prefrontal cortex. This phenomenon was more significant for the subgroup of patients with a favorable prognosis. These preliminary results imply that the ISI may be an important factor for SCS. The research paradigm proposed here also provides insights for further quantitative evaluations of the therapeutic effects of neuromodulation.

Natural Firing Patterns Imply Low Sensitivity of Synaptic Plasticity to Spike Timing Compared with Firing Rate

PubMed Central

Wallisch, Pascal; Ostojic, Srdjan

2016-01-01

Synaptic plasticity is sensitive to the rate and the timing of presynaptic and postsynaptic action potentials. In experimental protocols inducing plasticity, the imposed spike trains are typically regular and the relative timing between every presynaptic and postsynaptic spike is fixed. This is at odds with firing patterns observed in the cortex of intact animals, where cells fire irregularly and the timing between presynaptic and postsynaptic spikes varies. To investigate synaptic changes elicited by in vivo-like firing, we used numerical simulations and mathematical analysis of synaptic plasticity models. We found that the influence of spike timing on plasticity is weaker than expected from regular stimulation protocols. Moreover, when neurons fire irregularly, synaptic changes induced by precise spike timing can be equivalently induced by a modest firing rate variation. Our findings bridge the gap between existing results on synaptic plasticity and plasticity occurring in vivo, and challenge the dominant role of spike timing in plasticity. SIGNIFICANCE STATEMENT Synaptic plasticity, the change in efficacy of connections between neurons, is thought to underlie learning and memory. The dominant paradigm posits that the precise timing of neural action potentials (APs) is central for plasticity induction. This concept is based on experiments using highly regular and stereotyped patterns of APs, in stark contrast with natural neuronal activity. Using synaptic plasticity models, we investigated how irregular, in vivo-like activity shapes synaptic plasticity. We found that synaptic changes induced by precise timing of APs are much weaker than suggested by regular stimulation protocols, and can be equivalently induced by modest variations of the AP rate alone. Our results call into question the dominant role of precise AP timing for plasticity in natural conditions. PMID:27807166

Bacterial extract (OM-85) with human-equivalent doses does not inhibit the development of asthma in a murine model.

PubMed

Rodrigues, A; Gualdi, L P; de Souza, R G; Vargas, M H M; Nuñez, N K; da Cunha, A A; Jones, M H; Pinto, L A; Stein, R T; Pitrez, P M

OM-85 is an immunostimulant bacterial lysate, which has been proven effective in reducing the number of lower airways infections. We investigated the efficacy of the bacterial lysate OM-85 in the primary prevention of a murine model of asthma. In the first phase of our study the animals received doses of 0.5μg, 5μg and 50μg of OM-85 through gavage for five days (days -10 to -6 of the protocol), 10 days prior to starting the sensitisation with ovalbumin (OVA), in order to evaluate the results of dose-response protocols. A single dose (5μg) was then chosen in order to verify in detail the effect of OM-85 on the pulmonary allergic response. Total/differential cells count and cytokine levels (IL-4, IL-5, IL-13 and IFN-γ) from bronchoalveolar lavage fluid (BALF), OVA-specific IgE levels from serum, lung function and lung histopathological analysis were evaluated. OM-85 did not reduce pulmonary eosinophilic response, regardless of the dose used. In the phase protocol using 5μg/animal of OM-85, no difference was shown among the groups studied, including total cell and eosinophil counts in BALF, serum OVA-specific IgE, lung histopathologic findings and lung resistance. However, OM-85 decreased IL-5 and IL-13 levels in BALF. OM-85, administered in early life in mice in human-equivalent doses, does not inhibit the development of allergic pulmonary response in mice. Copyright © 2016 SEICAP. Published by Elsevier España, S.L.U. All rights reserved.

Water equivalent thickness of immobilization devices in proton therapy planning - Modelling at treatment planning and validation by measurements with a multi-layer ionization chamber.

PubMed

Fellin, Francesco; Righetto, Roberto; Fava, Giovanni; Trevisan, Diego; Amelio, Dante; Farace, Paolo

2017-03-01

To investigate the range errors made in treatment planning due to the presence of the immobilization devices along the proton beam path. The measured water equivalent thickness (WET) of selected devices was measured by a high-energy spot and a multi-layer ionization chamber and compared with that predicted by treatment planning system (TPS). Two treatment couches, two thermoplastic masks (both un-stretched and stretched) and one headrest were selected. At TPS, every immobilization device was modelled as being part of the patient. The following parameters were assessed: CT acquisition protocol, dose-calculation grid-sizes (1.5 and 3.0mm) and beam-entrance with respect to the devices (coplanar and non-coplanar). Finally, the potential errors produced by a wrong manual separation between treatment couch and the CT table (not present during treatment) were investigated. In the thermoplastic mask, there was a clear effect due to beam entrance, a moderate effect due to the CT protocols and almost no effect due to TPS grid-size, with 1mm errors observed only when thick un-stretched portions were crossed by non-coplanar beams. In the treatment couches the WET errors were negligible (<0.3mm) regardless of the grid-size and CT protocol. The potential range errors produced in the manual separation between treatment couch and CT table were small with 1.5mm grid-size, but could be >0.5mm with a 3.0mm grid-size. In the headrest, WET errors were negligible (0.2mm). With only one exception (un-stretched mask, non-coplanar beams), the WET of all the immobilization devices was properly modelled by the TPS. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.