Latency Of Behavioral Responses Research Articles

Overt Word Reading and Visual Object Naming in Adults with Dyslexia: Electroencephalography Study in Transparent Orthography.

The study aimed to investigate overt reading and naming processes in adult people with dyslexia (PDs) in shallow (transparent) language orthography. The results of adult PDs are compared with adult healthy controls HCs. Comparisons are made in three phases: pre-lexical (150-260 ms), lexical (280-700 ms), and post-lexical stage of processing (750-1000 ms) time window. Twelve PDs and HCs performed overt reading and naming tasks under EEG recording. The word reading and naming task consisted of sparse neighborhoods with closed phonemic onset (words/objects sharing the same onset). For the analysis of the mean ERP amplitude for pre-lexical, lexical, and post-lexical time window, a mixed design ANOVA was performed with the right (F4, FC2, FC6, C4, T8, CP2, CP6, P4) and left (F3, FC5, FC1, T7, C3, CP5, CP1, P7, P3) electrode sites, within-subject factors and group (PD vs. HC) as between-subject factor. Behavioral response latency results revealed significantly prolonged reading latency between HCs and PDs, while no difference was detected in naming response latency. ERP differences were found between PDs and HCs in the right hemisphere's pre-lexical time window (160-200 ms) for word reading aloud. For visual object naming aloud, ERP differences were found between PDs and HCs in the right hemisphere's post-lexical time window (900-1000 ms). The present study demonstrated different distributions of the electric field at the scalp in specific time windows between two groups in the right hemisphere in both word reading and visual object naming aloud, suggesting alternative processing strategies in adult PDs. These results indirectly support the view that adult PDs in shallow language orthography probably rely on the grapho-phonological route during overt word reading and have difficulties with phoneme and word retrieval during overt visual object naming in adulthood.

Behavioral hearing thresholds and response latencies in killer whales (Orcinus orca) depend on sound duration

Large odontocetes are considered at risk of auditory and behavioral impacts from sonar, and it is necessary to predict the effects of tonal sonar signals that have widely varying durations. Here, the effect of sound duration on hearing threshold and reaction time was investigated in two killer whales (Orcinus orca) using behavioral methods. Hearing tests were conducted using sounds between 50 μs and 2 s in duration for frequencies across the hearing range. Hearing thresholds within each frequency were dependent on sound duration, with threshold increasing with duration out to a plateau, which was used to calculate auditory integration time. Vocal response reaction time data showed decreasing latency with increasing signal level and length. These data were consistent with other marine mammal species and demonstrate that signal detection and behavior are affected by the duration of tonal sounds in killer whales.

Locus coeruleus and dorsal cingulate morphology contributions to slowed processing speed

Slowed information processing speed is a defining feature of cognitive aging. Nucleus locus coeruleus (LC) and medial prefrontal regions are targets for understanding slowed processing speed because these brain regions influence neural and behavioral response latencies through their roles in optimizing task performance. Although structural measures of medial prefrontal cortex have been consistently related to processing speed, it is unclear if 1) declines in LC structure underlie this association because of reciprocal connections between LC and medial prefrontal cortex, or 2) if LC declines provide a separate explanation for age-related changes in processing speed. LC and medial prefrontal structural measures were predicted to explain age-dependent individual differences in processing speed in a cross-sectional sample of 43 adults (19–79 years; 63% female). Higher turbo-spin echo LC contrast, based on a persistent homology measure, and greater dorsal cingulate cortical thickness were significantly and each uniquely related to faster processing speed. However, only dorsal cingulate cortical thickness appeared to statistically mediate age-related differences in processing speed. The results suggest that individual differences in cognitive processing speed can be attributed, in part, to structural variation in nucleus LC and medial prefrontal cortex, with the latter key to understanding why older adults exhibit slowed processing speed.

Evaluation of performance of hearing aid users using Acoustic Change Complex (ACC) and behavioral measures

ObjectiveTo validate the clinical use of Acoustic Change Complex (ACC) as an objective tool in children who use hearing Aids and explore how far ACC response parameters could be correlated to behavioral tests. MethodSixty Arabic speaking children, using binaural Hearing Aids (H.As), participated in the present study. Their age ranged from 6 to 12 years. Evaluation of Hearing aid device performance was performed through questionnaire, speech in noise tests and aided/unaided ACC recordings. Two stimuli '' vowel/o/with SNR (0 &+8) ''were developed and standardized to elicit ACC response. The replicated ACC waveforms were collected and analyzed and the aided ACC responses were compared with unaided ACC and correlated to behavioral tests. ResultsThe ACC percent identification in children using H.As using vowel/o/with SNR (+8 & 0) stimuli was 75% and 45% respectively in aided condition, the percent decreased to 40% and 15% in unaided condition. Speech in noise stimuli showed significant difference of ACC-N1 latency between the aided and unaided groups being longer in the unaided condition. The correlations between behavioral tests and ACC response (latency and amplitude) were irrelevant. ConclusionsHearing-impaired subjects can process speech stimulus at the level of the auditory cortex, and in a more effective manner when they used their H.As. ACC can be used as an objective measure for selective auditory attention ability using vowel-in-noise. However, it couldn't replace Behavioral measures.

Learning to predict: Neuronal signatures of auditory expectancy in human event-related potentials

Learning to anticipate future states of the world based on statistical regularities in the environment is a key component of perception and is vital for the survival of many organisms. Such statistical learning and prediction are crucial for acquiring language and music appreciation. Importantly, learned expectations can be implicitly derived from exposure to sensory input, without requiring explicit information regarding contingencies in the environment. Whereas many previous studies of statistical learning have demonstrated larger neuronal responses to unexpected versus expected stimuli, the neuronal bases of the expectations themselves remain poorly understood. Here we examined behavioral and neuronal signatures of learned expectancy via human scalp-recorded event-related brain potentials (ERPs). Participants were instructed to listen to a series of sounds and press a response button as quickly as possible upon hearing a target noise burst, which was either reliably or unreliably preceded by one of three pure tones in low-, mid-, and high-frequency ranges. Participants were not informed about the statistical contingencies between the preceding tone ‘cues’ and the target. Over the course of a stimulus block, participants responded more rapidly to reliably cued targets. This behavioral index of learned expectancy was paralleled by a negative ERP deflection, designated as a neuronal contingency response (CR), which occurred immediately prior to the onset of the target. The amplitude and latency of the CR were systematically modulated by the strength of the predictive relationship between the cue and the target. Re-averaging ERPs with respect to the latency of behavioral responses revealed no consistent relationship between the CR and the motor response, suggesting that the CR represents a neuronal signature of learned expectancy or anticipatory attention. Our results demonstrate that statistical regularities in an auditory input stream can be implicitly learned and exploited to influence behavior. Furthermore, we uncover a potential ‘prediction signal’ that reflects this fundamental learning process.

Measuring attentional bias to food cues in young children using a visual search task: An eye-tracking study

ObjectiveAttentional bias to food cues may be a risk factor for childhood obesity, yet there are few paradigms to measure such biases in young children. Therefore, the present work introduces an eye-tracking visual search task to measure attentional bias in young children. Methods: Fifty-one 3-6-year-olds played a game to find a target cartoon character among food (experimental condition) or toy (control condition) distractors. Children completed the experimental and toy conditions on two separate visits in randomized order. Behavioral (response latencies) and eye-tracking measures (time to first fixation, initial gaze duration duration, cumulative gaze duration ) of attention to food and toy cues were computed. Regressions were used to test for attentional bias to food versus toy cues, and whether attentional bias to food cues was related to current BMI z-score. Results: Children spent more cumulative time looking at food versus toy distractors and took longer to locate the target when searching through food versus toy distractors. The faster children fixated on their first food versus toy distractor was associated with higher BMI z-scores. Conclusions: Using a game-based paradigm employing eye-tracking, we found a behavioral attentional bias to food vs. toy distractors in young children. Further, attentional bias to food cues was associated with current BMI z-score.

Analysis of the Emotional-Cognitive Processes using a Modified Multisource Interference Task and Recording of EEG and Behavioral Responses

We investigated changes in the EEG signals and the latency of behavioral responses in the cognitive test with interfering emotional stimuli. It was hypothesized that the cognitive process would be not only influenced by emotional factors but would also result in different patterns by emotional types (e.g., annoyance, happiness, neutrality, etc.) We developed a new method, the modified multisource interference task (mMSIT), to test our hypotheses. The EEG signals and behavioral responses were collected. Participants were required to press a button after stimulation; simultaneously, four-channel EEGs (F3, F4, Cz, and Pz) were recorded from 21 healthy participants. Event-related potentials (ERPs) and time-frequency EEG spectrograms were analyzed. Behavioral patterns were quantified by measuring the reaction times and error rates for button pressing. The P2 amplitudes at presentation of images of annoyed faces were found to be significantly lower than those for neutral and happy interference faces. The spectral powers of the β range in F4 and Pz were also significantly smaller in annoyed interference compared to others. Additionally, the latency of behavioral responses for annoyed faces was significantly longer compared to that for happy faces. However, an error rate increase for annoyed faces was not observed. These results show that electrophysiological responses and behavioral reactions are significantly affected at visual perception of annoyed faces. Our findings demonstrate that negative emotional interference can increase the load of cognitive processing as a distractor, and our results show that the mMSIT is a useful task in studies of normal human cognition and emotions.

Impulsivity and Response Latency in Non-Suicidal Self-Injury: The Role of Negative Urgency in Emotion Regulation.

Impulsivity is thought to be a contributing factor in non-suicidal self-injury (NSSI), yet the research is limited and inconsistent. In particular, little is known about how impulsivity is associated with response latency between initial urge and later self-injury, emotion regulation processes, or severity of NSSI. In this study, we tested group differences between participants with and without a history of NSSI on a questionnaire measure of impulsivity. In addition, we tested hypothesized correlations between impulsivity and relevant variables within the NSSI sample using questionnaires and self-reported response latency between urge and injury. Participants included 159 undergraduate students, 84 with an NSSI history and 75 without an NSSI history. Results indicated greater impulsivity on facets of Urgency and (lack of) Perseverance for the NSSI group. Within the NSSI sample, facets of impulsivity were associated with difficulties in emotion regulation and NSSI severity, but not response latency. In addition, response latency, a possible behavioral marker of impulsivity, was not associated with emotion regulation processes or NSSI frequency. These results suggest that higher scores on self-report measures of impulsivity, but not behavioral response latency measures, are associated with emotion regulation processes in individuals who self-injure.

Elucidating Underlying Processes of Psychometric Intelligence: A Comparison of Behavioral Response Latency and P3 Latency in a Modified Hick Reaction Time Paradigm

The present longitudinal study examined the role of positivity in predicting ego-resiliency over a 10-year period. Participants were 373 middle adolescents (46.9% males) assessed during the transition into young adulthood. The mean age of participants was 16.9 years at the beginning of the study and 25.9 years at the end. An autoregressive cross-lagged model was used to investigate the prediction of positivity from ego-resiliency. At each time point, positivity predicted later ego-resiliency above and beyond its high stability. Ego-resiliency, instead, did not predict positivity. These results provide corroboration from a longitudinal perspective of previous findings highlighting the potential benefits of positive emotion for helping people to cope successfully with stressful events during their lives. The theoretical and practical implications of these results are discussed.

Time to Loss of Consciousness and Its Relation to Behavior in Slaughter Pigs during Stunning with 80 or 95% Carbon Dioxide.

Exposure to CO2 at high concentration is a much debated stunning method in pigs. Pigs respond aversively to high concentrations of CO2, and there is uncertainty about what behaviors occur before and after loss of consciousness. The aim was to assess timing of unconsciousness in pigs during exposure to high concentrations of CO2 based on changes in electroencephalogram (EEG) activity and the relation with the behaviors sniffing, retreat and escape attempts, lateral head movements, jumping, muscular contractions, loss of posture, and gasping. Pigs (108 ± 9 kg) were randomly assigned to 80% CO2 (80C, n = 24) or 95% CO2 (95C, n = 24). The time at which the gondola started descending into the well pre-filled with 80C or 95C was marked as T = 0. The CO2 exposure lasted 346 s after which the corneal reflex and breathing were assessed for 1 min. Visual assessment of changes in the amplitude and frequency of EEG traces after T = 0 was used to determine loss of consciousness. Time to loss of consciousness was longer in 80C pigs (47 ± 6 s) than in 95C pigs (33 ± 7 s). Time to an iso-electric EEG was similar in 80C pigs (75 ± 23 s) and 95C pigs (64 ± 32 s). When pigs descended into the well, the earlier entry of 95C pigs into high CO2 atmosphere rather than the concentration of CO2 by itself affected the latency of behavioral responses and decreasing brain activity. During exposure to the gas, 80C and 95C pigs exhibited sniffing, retreat attempts, lateral head movements, jumping, and gasping before loss of consciousness. 95C pigs exhibited all these behaviors on average earlier than 80C pigs after T = 0. But the interval between onset of these behaviors and loss of consciousness and the duration of these behaviors, except gasping, was similar for both treatments. Loss of posture was on average observed in both groups 10 s before EEG-based loss of consciousness. Furthermore, 88% of 80C pigs and 94% of 95C pigs demonstrated muscular contractions before loss of consciousness. The findings provide little reason to conclude on a behavioral basis that these atmospheres are greatly different in their impact on pig welfare.

Acute ethanol effects on neural encoding of reward size and delay in the nucleus accumbens.

Acute ethanol administration can cause impulsivity, resulting in increased preference for immediately available rewards over delayed but more valuable alternatives. The manner in which reward size and delay are represented in neural firing is not fully understood, and very little is known about ethanol effects on this encoding. To address this issue, we used in vivo electrophysiology to characterize neural firing in the core of the nucleus accumbens (NAcc) in rats responding for rewards that varied in size or delay after vehicle or ethanol administration. The NAcc is a central element in the circuit that governs decision-making and importantly, promotes choice of delayed rewards. We found that NAcc firing in response to reward-predictive cues encoded anticipated reward value after vehicle administration, but ethanol administration disrupted this encoding, resulting in a loss of discrimination between immediate and delayed rewards in cue-evoked neural responses. In addition, NAcc firing occurring at the time of the operant response (lever pressing) was inversely correlated with behavioral response latency, such that increased firing rates were associated with decreased latencies to lever press. Ethanol administration selectively attenuated this lever press-evoked firing when delayed but not immediate rewards were expected. These effects on neural firing were accompanied by increased behavioral latencies to respond for delayed rewards. Our results suggest that ethanol effects on NAcc cue- and lever press-evoked encoding may contribute to ethanol-induced impulsivity.

Mindful Aging: The Effects of Regular Brief Mindfulness Practice on Electrophysiological Markers of Cognitive and Affective Processing in Older Adults

There is growing interest in the potential benefits of mindfulness meditation practices in terms of counteracting some of the cognitive effects associated with aging. Pursuing this question, the aim of the present study was to investigate the influence of mindfulness training on executive control and emotion regulation in older adults, by means of studying behavioral and electrophysiological changes. Participants, 55 to 75 years of age, were randomly allocated to an 8-week mindful breath awareness training group or an active control group engaging in brain training exercises. Before and after the training period, participants completed an emotional-counting Stroop task, designed to measure attentional control and emotion regulation processes. Concurrently, their brain activity was measured by means of 64-channel electroencephalography. The results show that engaging in just over 10 min of mindfulness practice five times per week resulted in significant improvements in behavioral (response latency) and electrophysiological (N2 event-related potential) measures related to general task performance. Analyses of the underlying cortical sources (Variable Resolution Electromagnetic Tomography, VARETA) indicate that this N2-related effect is primarily associated with changes in the right angular gyrus and other areas of the dorsal attention network. However, the study did not find the expected specific improvements in executive control and emotion regulation, which may be due to the training instructions or the relative brevity of the intervention. Overall, the results indicate that engaging in mindfulness meditation training improves the maintenance of goal-directed visuospatial attention and may be a useful strategy for counteracting cognitive decline associated with aging.

Cellular evidence for efference copy in Drosophila visuomotor processing.

Each time a locomoting fly turns, the visual image sweeps over the retina and generates a motion stimulus. Classic behavioral experiments suggested that flies use active neural-circuit mechanisms to suppress the perception of self-generated visual motion during intended turns. Direct electrophysiological evidence, however, has been lacking. We found that visual neurons in Drosophila receive motor-related inputs during rapid flight turns. These inputs arrived with a sign and latency appropriate for suppressing each targeted cell's visual response to the turn. Precise measurements of behavioral and neuronal response latencies supported the idea that motor-related inputs to optic flow-processing cells represent internal predictions of the expected visual drive induced by voluntary turns. Motor-related inputs to small object-selective visual neurons could reflect either proprioceptive feedback from the turn or internally generated signals. Our results in Drosophila echo the suppression of visual perception during rapid eye movements in primates, demonstrating common functional principles of sensorimotor processing across phyla.

Neural correlates of individual differences in processing of rising tones in Cantonese: Implications for speech perception and production

Neural correlates of individual differences in processing of rising tones in Cantonese: Implications for speech perception and production

Temporal Features of Spike Trains in the Moth Antennal Lobe Revealed by a Comparative Time-Frequency Analysis

The discrimination of complex sensory stimuli in a noisy environment is an immense computational task. Sensory systems often encode stimulus features in a spatiotemporal fashion through the complex firing patterns of individual neurons. To identify these temporal features, we have developed an analysis that allows the comparison of statistically significant features of spike trains localized over multiple scales of time-frequency resolution. Our approach provides an original way to utilize the discrete wavelet transform to process instantaneous rate functions derived from spike trains, and select relevant wavelet coefficients through statistical analysis. Our method uncovered localized features within olfactory projection neuron (PN) responses in the moth antennal lobe coding for the presence of an odor mixture and the concentration of single component odorants, but not for compound identities. We found that odor mixtures evoked earlier responses in biphasic response type PNs compared to single components, which led to differences in the instantaneous firing rate functions with their signal power spread across multiple frequency bands (ranging from 0 to 45.71 Hz) during a time window immediately preceding behavioral response latencies observed in insects. Odor concentrations were coded in excited response type PNs both in low frequency band differences (2.86 to 5.71 Hz) during the stimulus and in the odor trace after stimulus offset in low (0 to 2.86 Hz) and high (22.86 to 45.71 Hz) frequency bands. These high frequency differences in both types of PNs could have particular relevance for recruiting cellular activity in higher brain centers such as mushroom body Kenyon cells. In contrast, neurons in the specialized pheromone-responsive area of the moth antennal lobe exhibited few stimulus-dependent differences in temporal response features. These results provide interesting insights on early insect olfactory processing and introduce a novel comparative approach for spike train analysis applicable to a variety of neuronal data sets.

Enhanced sensitivity to rare, emotion-irrelevant stimuli in females: neural correlates

Numerous studies showed enhanced sensitivity of females to emotional stimuli relative to males using multiple tasks. However, in the present study, two event-related potential (ERP) experiments targeting the impact of gender on rare stimulus processing both showed enhanced sensitivity of females to rare stimulus that is neutral, irrelevant to emotion. Subjects were required to press different keys for standard and rare pictures in Experiment 1, and to do nothing but to passively view the pictures in Experiment 2. Rare pictures elicited more intense pop-out effects in females, at both neuroelectrical (multiple levels of ERP analyses) and behavioral (response latencies and pop-out assessment) levels across experiments. Thus, females are equipped with enhanced sensitivity to rare, emotion-irrelevant stimuli relative to males, probably as a result of evolutionary adaptation. This effect is ought to be considered in studies that use an oddball paradigm.

Perceptual ambiguity of bistable visual stimuli causes no or little increase in perceptual latency

Cognitive ambiguity, such as found in categorical judgments, increases behavioral response latency. Here we examined whether perceptual ambiguity for bistable stimuli, stimuli in which two perceptual interpretations were mutually competitive, also increased perceptual latency. We presented a bistable stimulus and measured the observer's reaction time to judge which of two possible percepts was seen. Perceptual ambiguity was systematically manipulated and how it affected the response latency was examined. The first experiment used a motion-defined rotating cylinder. The observers judged the rotation direction, and the perceptual ambiguity was controlled by binocular disparity. The second experiment used Rubin's vase. The observers judged whether the figure was a vase or faces, and the perceptual ambiguity was controlled by luminance of the surround. In both experiments, we found that the perceptual ambiguity caused only a small or no increase in reaction time and, presumably, in the perceptual latency included in the reaction time. These findings suggest that perceptual competition does not have a strong effect on the latency of the initial perception of bistable stimuli. Given that many perceptual problems are under-constrained as in the cases of bistable stimuli, it is presumably ecologically functional for the brain to establish perception as quickly as possible regardless of the presence of potential alternatives.

Temporal frequency modulates reaction time responses to first-order and second-order motion.

This study investigated the effect of temporal frequency and modulation depth on reaction times for discriminating the direction of first-order (luminance-defined) and second-order (contrast-defined) motion, equated for visibility using equal multiples of direction-discrimination threshold. Results showed that reaction times were heavily influenced by temporal frequency, especially in the case of second-order motion. At 1 Hz, reaction times were faster for first-order compared with second-order motion. As temporal frequency increased, reaction times for first-order motion decreased slightly, but those for second-order motion decreased more rapidly. At 8 Hz, reaction times for second-order motion were, in many cases, faster than those for first-order motion. Reaction times decreased as stimulus modulation depth increased at approximately the same rate for both motion types. The findings demonstrate that behavioral response latencies to first-order and second-order motion are dependent on specific stimulus parameters and may, in some cases, be shorter in response to second-order compared with first-order motion.

Stimulus-Induced and State-Dependent Sustained Gamma Activity Is Tightly Coupled to the Hemodynamic Response in Humans

A prompt behavioral response to a stimulus depends both on the salience of the stimulus as well as the subject's preparedness. Thus, both stimulus properties and cognitive factors, such as attention, may determine the strength of neuronal synchronization in the gamma range. For a comprehensive investigation of stimulus-response processing through noninvasive imaging, it is, however, a crucial issue whether both kinds of gamma modulation elicit a hemodynamic response. Here, we show that, in the human visual cortex, stimulus strength and internal state modulate sustained gamma activity and hemodynamic response in close correspondence. When participants reported velocity changes of gratings varying in contrast, gamma activity (35-70 Hz) increased systematically with contrast. For stimuli of constant contrast, the amplitude of gamma activity before the behaviorally relevant velocity change was inversely correlated to the behavioral response latency. This indicates that gamma activity also reflects an overall attentive state. For both sources of variance, gamma activity was tightly coupled to the hemodynamic response measured through optical topography. Because of the close relationship between high-frequency neuronal activity and the hemodynamic signal, we conclude that both stimulus-induced and state-dependent gamma activity trigger a metabolic demand and are amenable to vascular-based imaging.

Tactile stimulation accelerates behavioral responses to visual stimuli through enhancement of occipital gamma-band activity

We investigated how responses of occipital cortex to visual stimuli are modulated by simultaneously presented tactile stimuli. Magnetoencephalography was recorded while subjects performed a simple reaction time task. Presence of a task-irrelevant tactile stimulus leads to faster behavioral responses and earlier and stronger gamma-band synchronization in occipital cortex, irrespective of the relative location of the tactile stimulus. While also other stimulus related responses in occipital cortex were modulated (alpha-band and evoked responses in parieto-occipital region), correlation-analysis revealed induced gamma-band activity to be the best predictor of the faster behavioral response latencies, suggesting a key-role of oscillatory activity for cross-modal integration.