Browsing by Author "Appelbaum, L Gregory"

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Open Access
A Common Mechanism for Perceptual Reversals in Motion-Induced Blindness, the Troxler Effect, and Perceptual Filling-In.
(Perception, 2016-10-03) Devyatko, Dina; Appelbaum, L Gregory; Mitroff, Stephen R
Several striking visual phenomena involve a physically present stimulus that alternates between being perceived and being "invisible." For example, motion-induced blindness, the Troxler effect, and perceptual filling-in all consist of subjective alternations where an item repeatedly changes from being seen to unseen. In the present study, we explored whether these three specific visual phenomena share any commonalities in their alternation rates and patterns to better understand the mechanisms of each. Data from 69 individuals revealed moderate to strong correlations across the three phenomena for the number of perceptual disappearances and the accumulated duration of the disappearances. Importantly, these effects were not correlated with eye movement patterns (saccades) assessed through eye tracking, differences in motion sensitivity as indexed by dot coherence and speed perception thresholds, or simple reaction time abilities. Principal component analyses revealed a single component that explained 67% of the variance for the number of perceptual reversals and 60% for the accumulated duration of the disappearances. The temporal dynamics of illusory disappearances was also compared for each phenomenon, and normalized durations of disappearances were well fit by a gamma distribution with similar shape parameters for each phenomenon, suggesting that they may be driven by a single oscillatory mechanism.
Open Access
A Randomized Controlled Trial Investigating the Feasibility and Adherence to an Aerobic Training Program in Healthy Individuals.
(Journal of sport rehabilitation, 2019-09) Teel, Elizabeth F; Marshall, Stephen W; Appelbaum, L Gregory; Battaglini, Claudio L; Carneiro, Kevin A; Guskiewicz, Kevin M; Register-Mihalik, Johna K; Mihalik, Jason P
CONTEXT:Concussion management is moving from passive rest strategies to active interventions, including aerobic exercise therapy. Little information is available regarding the feasibility and adherence of these programs. OBJECTIVES:To determine whether an aerobic exercise training program intended for rehabilitation in people with concussion is feasible. Healthy, nonconcussed subjects were studied in this phase 1 trial. DESIGN:Phase 1 parallel-group, randomized controlled trial in a sample of healthy (nonconcussed), recreationally active university students. SETTING:Laboratory. PATIENTS:40 healthy university students. METHODS:Participants were equally randomized to acute concussion therapy intervention (ACTIVE) training or nontraining groups. All participants completed maximal cardiopulmonary exercise tests on a stationary cycle ergometer at 2 test sessions approximately 14 days apart. During this 2-week study period, ACTIVE training participants completed six 30-minute cycling sessions, progressing from 60% to 80% of the participant's individualized maximal oxygen consumption. A subset of participants (NACTIVE = 12, Nnontraining = 11) wore physical activity monitors throughout the 2-week study period. MAIN OUTCOMES MEASURES:Study protocol and randomization effectiveness, exercise safety and adherence, and progressive intensity of the ACTIVE training procedures. RESULTS:No adverse events occurred during any exercise sessions. Twelve ACTIVE training participants (60%) completed all training sessions, and every participant completed at least 4 sessions. Heart rate increased throughout the training period (P < .001), but symptom changes and training adherence remained stable despite the progressively increasing workload. ACTIVE training participants completed approximately 30 additional minutes of physical activity on training sessions days, although that was not statistically significant (P = .20). CONCLUSIONS:University-aged students were adherent to the ACTIVE training protocol. Future research should investigate the safety and feasibility of aerobic training programs in acutely concussed individuals to determine their appropriateness as a clinical rehabilitation strategy.
Open Access
Action video game playing is associated with improved visual sensitivity, but not alterations in visual sensory memory.
(Atten Percept Psychophys, 2013-08) Appelbaum, L Gregory; Cain, Matthew S; Darling, Elise F; Mitroff, Stephen R
Action video game playing has been experimentally linked to a number of perceptual and cognitive improvements. These benefits are captured through a wide range of psychometric tasks and have led to the proposition that action video game experience may promote the ability to extract statistical evidence from sensory stimuli. Such an advantage could arise from a number of possible mechanisms: improvements in visual sensitivity, enhancements in the capacity or duration for which information is retained in visual memory, or higher-level strategic use of information for decision making. The present study measured the capacity and time course of visual sensory memory using a partial report performance task as a means to distinguish between these three possible mechanisms. Sensitivity measures and parameter estimates that describe sensory memory capacity and the rate of memory decay were compared between individuals who reported high evels and low levels of action video game experience. Our results revealed a uniform increase in partial report accuracy at all stimulus-to-cue delays for action video game players but no difference in the rate or time course of the memory decay. The present findings suggest that action video game playing may be related to enhancements in the initial sensitivity to visual stimuli, but not to a greater retention of information in iconic memory buffers.
Open Access
Distress tolerance to auditory feedback and functional connectivity with the auditory cortex.
(Psychiatry research. Neuroimaging, 2018-12) Addicott, Merideth A; Daughters, Stacey B; Strauman, Timothy J; Appelbaum, L Gregory
Distress tolerance is the capacity to withstand negative affective states in pursuit of a goal. Low distress tolerance may bias an individual to avoid or escape experiences that induce affective distress, but the neural mechanisms underlying the bottom-up generation of distress and its relationship to behavioral avoidance are poorly understood. During a neuroimaging scan, healthy participants completed a mental arithmetic task with easy and distress phases, which differed in cognitive demands and positive versus negative auditory feedback. Then, participants were given the opportunity to continue playing the distress phase for a financial bonus and were allowed to quit at any time. The persistence duration was the measure of distress tolerance. The easy and distress phases activated auditory cortices and fronto-parietal regions. A task-based functional connectivity analysis using the left secondary auditory cortex (i.e., planum temporale) as the seed region revealed stronger connectivity to fronto-parietal regions and anterior insula during the distress phase. The distress-related connectivity between the seed region and the left anterior insula was negatively correlated with distress tolerance. The results provide initial evidence of the role of the anterior insula as a mediating link between the bottom-up generation of affective distress and top-down behavioral avoidance of distress.
Open Access
Improved Visual Cognition through Stroboscopic Training.
(Front Psychol, 2011) Appelbaum, L Gregory; Schroeder, Julia E; Cain, Matthew S; Mitroff, Stephen R
Humans have a remarkable capacity to learn and adapt, but surprisingly little research has demonstrated generalized learning in which new skills and strategies can be used flexibly across a range of tasks and contexts. In the present work we examined whether generalized learning could result from visual-motor training under stroboscopic visual conditions. Individuals were assigned to either an experimental condition that trained with stroboscopic eyewear or to a control condition that underwent identical training with non-stroboscopic eyewear. The training consisted of multiple sessions of athletic activities during which participants performed simple drills such as throwing and catching. To determine if training led to generalized benefits, we used computerized measures to assess perceptual and cognitive abilities on a variety of tasks before and after training. Computer-based assessments included measures of visual sensitivity (central and peripheral motion coherence thresholds), transient spatial attention (a useful field of view - dual task paradigm), and sustained attention (multiple-object tracking). Results revealed that stroboscopic training led to significantly greater re-test improvement in central visual field motion sensitivity and transient attention abilities. No training benefits were observed for peripheral motion sensitivity or peripheral transient attention abilities, nor were benefits seen for sustained attention during multiple-object tracking. These findings suggest that stroboscopic training can effectively improve some, but not all aspects of visual perception and attention.
Open Access
Improvement in visual search with practice: mapping learning-related changes in neurocognitive stages of processing.
(J Neurosci, 2015-04-01) Clark, Kait; Appelbaum, L Gregory; van den Berg, Berry; Mitroff, Stephen R; Woldorff, Marty G
Practice can improve performance on visual search tasks; the neural mechanisms underlying such improvements, however, are not clear. Response time typically shortens with practice, but which components of the stimulus-response processing chain facilitate this behavioral change? Improved search performance could result from enhancements in various cognitive processing stages, including (1) sensory processing, (2) attentional allocation, (3) target discrimination, (4) motor-response preparation, and/or (5) response execution. We measured event-related potentials (ERPs) as human participants completed a five-day visual-search protocol in which they reported the orientation of a color popout target within an array of ellipses. We assessed changes in behavioral performance and in ERP components associated with various stages of processing. After practice, response time decreased in all participants (while accuracy remained consistent), and electrophysiological measures revealed modulation of several ERP components. First, amplitudes of the early sensory-evoked N1 component at 150 ms increased bilaterally, indicating enhanced visual sensory processing of the array. Second, the negative-polarity posterior-contralateral component (N2pc, 170-250 ms) was earlier and larger, demonstrating enhanced attentional orienting. Third, the amplitude of the sustained posterior contralateral negativity component (SPCN, 300-400 ms) decreased, indicating facilitated target discrimination. Finally, faster motor-response preparation and execution were observed after practice, as indicated by latency changes in both the stimulus-locked and response-locked lateralized readiness potentials (LRPs). These electrophysiological results delineate the functional plasticity in key mechanisms underlying visual search with high temporal resolution and illustrate how practice influences various cognitive and neural processing stages leading to enhanced behavioral performance.
Open Access
Mapping the semantic structure of cognitive neuroscience.
(J Cogn Neurosci, 2014-09) Beam, Elizabeth; Appelbaum, L Gregory; Jack, Jordynn; Moody, James; Huettel, Scott A
Cognitive neuroscience, as a discipline, links the biological systems studied by neuroscience to the processing constructs studied by psychology. By mapping these relations throughout the literature of cognitive neuroscience, we visualize the semantic structure of the discipline and point to directions for future research that will advance its integrative goal. For this purpose, network text analyses were applied to an exhaustive corpus of abstracts collected from five major journals over a 30-month period, including every study that used fMRI to investigate psychological processes. From this, we generate network maps that illustrate the relationships among psychological and anatomical terms, along with centrality statistics that guide inferences about network structure. Three terms--prefrontal cortex, amygdala, and anterior cingulate cortex--dominate the network structure with their high frequency in the literature and the density of their connections with other neuroanatomical terms. From network statistics, we identify terms that are understudied compared with their importance in the network (e.g., insula and thalamus), are underspecified in the language of the discipline (e.g., terms associated with executive function), or are imperfectly integrated with other concepts (e.g., subdisciplines like decision neuroscience that are disconnected from the main network). Taking these results as the basis for prescriptive recommendations, we conclude that semantic analyses provide useful guidance for cognitive neuroscience as a discipline, both by illustrating systematic biases in the conduct and presentation of research and by identifying directions that may be most productive for future research.
Open Access
Mapping the structure of perceptual and visual-motor abilities in healthy young adults.
(Acta Psychol (Amst), 2015-05) Wang, Lingling; Krasich, Kristina; Bel-Bahar, Tarik; Hughes, Lauren; Mitroff, Stephen R; Appelbaum, L Gregory
The ability to quickly detect and respond to visual stimuli in the environment is critical to many human activities. While such perceptual and visual-motor skills are important in a myriad of contexts, considerable variability exists between individuals in these abilities. To better understand the sources of this variability, we assessed perceptual and visual-motor skills in a large sample of 230 healthy individuals via the Nike SPARQ Sensory Station, and compared variability in their behavioral performance to demographic, state, sleep and consumption characteristics. Dimension reduction and regression analyses indicated three underlying factors: Visual-Motor Control, Visual Sensitivity, and Eye Quickness, which accounted for roughly half of the overall population variance in performance on this battery. Inter-individual variability in Visual-Motor Control was correlated with gender and circadian patters such that performance on this factor was better for males and for those who had been awake for a longer period of time before assessment. The current findings indicate that abilities involving coordinated hand movements in response to stimuli are subject to greater individual variability, while visual sensitivity and occulomotor control are largely stable across individuals.
Open Access
Sensorimotor abilities predict on-field performance in professional baseball.
(Scientific reports, 2018-01-08) Burris, Kyle; Vittetoe, Kelly; Ramger, Benjamin; Suresh, Sunith; Tokdar, Surya T; Reiter, Jerome P; Appelbaum, L Gregory
Baseball players must be able to see and react in an instant, yet it is hotly debated whether superior performance is associated with superior sensorimotor abilities. In this study, we compare sensorimotor abilities, measured through 8 psychomotor tasks comprising the Nike Sensory Station assessment battery, and game statistics in a sample of 252 professional baseball players to evaluate the links between sensorimotor skills and on-field performance. For this purpose, we develop a series of Bayesian hierarchical latent variable models enabling us to compare statistics across professional baseball leagues. Within this framework, we find that sensorimotor abilities are significant predictors of on-base percentage, walk rate and strikeout rate, accounting for age, position, and league. We find no such relationship for either slugging percentage or fielder-independent pitching. The pattern of results suggests performance contributions from both visual-sensory and visual-motor abilities and indicates that sensorimotor screenings may be useful for player scouting.
Open Access
Sensorimotor learning during a marksmanship task in immersive virtual reality
(Frontiers in Psychology, 2018-02-06) Rao, Hrishikesh M; Khanna, Rajan; Zielinski, David J; Lu, Yvonne; Clements, Jillian M; Potter, Nicholas D; Sommer, Marc A; Kopper, Regis; Appelbaum, L Gregory
Sensorimotor learning refers to improvements that occur through practice in the performance of sensory-guided motor behaviors. Leveraging novel technical capabilities of an immersive virtual environment, we probed the component kinematic processes that mediate sensorimotor learning. Twenty naïve subjects performed a simulated marksmanship task modeled after Olympic Trap Shooting standards. We measured movement kinematics and shooting performance as participants practiced 350 trials while receiving trial-by-trial feedback about shooting success. Spatiotemporal analysis of motion tracking elucidated the ballistic and refinement phases of hand movements. We found systematic changes in movement kinematics that accompanied improvements in shot accuracy during training, though reaction and response times did not change over blocks. In particular, we observed longer, slower, and more precise ballistic movements that replaced effort spent on corrections and refinement. Collectively, these results leverage developments in immersive virtual reality technology to quantify and compare the kinematics of movement during early learning of full body sensorimotor orienting.
Open Access
Strategic allocation of attention reduces temporally predictable stimulus conflict.
(J Cogn Neurosci, 2012-09) Appelbaum, L Gregory; Boehler, Carsten N; Won, Robert; Davis, Lauren; Woldorff, Marty G
Humans are able to continuously monitor environmental situations and adjust their behavioral strategies to optimize performance. Here we investigate the behavioral and brain adjustments that occur when conflicting stimulus elements are, or are not, temporally predictable. ERPs were collected while manual response variants of the Stroop task were performed in which the SOAs between the relevant color and irrelevant word stimulus components were either randomly intermixed or held constant within each experimental run. Results indicated that the size of both the neural and behavioral effects of stimulus incongruency varied with the temporal arrangement of the stimulus components, such that the random-SOA arrangements produced the greatest incongruency effects at the earliest irrelevant first SOA (-200 msec) and the constant-SOA arrangements produced the greatest effects with simultaneous presentation. These differences in conflict processing were accompanied by rapid (∼150 msec) modulations of the sensory ERPs to the irrelevant distractor components when they occurred consistently first. These effects suggest that individuals are able to strategically allocate attention in time to mitigate the influence of a temporally predictable distractor. As these adjustments are instantiated by the participants without instruction, they reveal a form of rapid strategic learning for dealing with temporally predictable stimulus incongruency.
Open Access
Stroboscopic visual training improves information encoding in short-term memory.
(Atten Percept Psychophys, 2012-11) Appelbaum, L Gregory; Cain, Matthew S; Schroeder, Julia E; Darling, Elise F; Mitroff, Stephen R
The visual system has developed to transform an undifferentiated and continuous flow of information into discrete and manageable representations, and this ability rests primarily on the uninterrupted nature of the input. Here we explore the impact of altering how visual information is accumulated over time by assessing how intermittent vision influences memory retention. Previous work has shown that intermittent, or stroboscopic, visual training (i.e., practicing while only experiencing snapshots of vision) can enhance visual-motor control and visual cognition, yet many questions remain unanswered about the mechanisms that are altered. In the present study, we used a partial-report memory paradigm to assess the possible changes in visual memory following training under stroboscopic conditions. In Experiment 1, the memory task was completed before and immediately after a training phase, wherein participants engaged in physical activities (e.g., playing catch) while wearing either specialized stroboscopic eyewear or transparent control eyewear. In Experiment 2, an additional group of participants underwent the same stroboscopic protocol but were delayed 24 h between training and assessment, so as to measure retention. In comparison to the control group, both stroboscopic groups (immediate and delayed retest) revealed enhanced retention of information in short-term memory, leading to better recall at longer stimulus-to-cue delays (640-2,560 ms). These results demonstrate that training under stroboscopic conditions has the capacity to enhance some aspects of visual memory, that these faculties generalize beyond the specific tasks that were trained, and that trained improvements can be maintained for at least a day.
Open Access
The dynamics of proactive and reactive cognitive control processes in the human brain.
(J Cogn Neurosci, 2014-05) Appelbaum, L Gregory; Boehler, C Nicolas; Davis, Lauren A; Won, Robert J; Woldorff, Marty G
In this study, we leveraged the high temporal resolution of EEG to examine the neural mechanisms underlying the flexible regulation of cognitive control that unfolds over different timescales. We measured behavioral and neural effects of color-word incongruency, as different groups of participants performed three different versions of color-word Stroop tasks in which the relative timing of the color and word features varied from trial to trial. For this purpose, we used a standard Stroop color identification task with equal congruent-to-incongruent proportions (50%/50%), along with two versions of the "Reverse Stroop" word identification tasks, for which we manipulated the incongruency proportion (50%/50% and 80%/20%). Two canonical ERP markers of neural processing of stimulus incongruency, the frontocentral negative polarity incongruency wave (NINC) and the late positive component (LPC), were evoked across the various conditions. Results indicated that color-word incongruency interacted with the relative feature timing, producing greater neural and behavioral effects when the task-irrelevant stimulus preceded the target, but still significant effects when it followed. Additionally, both behavioral and neural incongruency effects were reduced by nearly half in the word identification task (Reverse Stroop 50/50) relative to the color identification task (Stroop 50/50), with these effects essentially fully recovering when incongruent trials appeared only infrequently (Reverse Stroop 80/20). Across the conditions, NINC amplitudes closely paralleled RTs, indicating this component is sensitive to the overall level of stimulus conflict. In contrast, LPC amplitudes were largest with infrequent incongruent trials, suggesting a possible readjustment role when proactive control is reduced. These findings thus unveil distinct control mechanisms that unfold over time in response to conflicting stimulus input under different contexts.
Open Access
The influence of different Stop-signal response time estimation procedures on behavior-behavior and brain-behavior correlations.
(Behav Brain Res, 2012-04-01) Boehler, C Nicolas; Appelbaum, L Gregory; Krebs, Ruth M; Hopf, Jens-Max; Woldorff, Marty G
The fundamental cognitive-control function of inhibitory control over motor behavior has been extensively investigated using the Stop-signal task. The critical behavioral parameter describing stopping efficacy is the Stop-signal response time (SSRT), and correlations with estimates of this parameter are commonly used to establish that other variables (e.g., other behavioral measures or brain activity measures) are closely related to inhibitory motor control. Recently, however, it has been argued that SSRT estimates can be strongly distorted if participants strategically slow down their responses over the course of the experiment, resulting in the SSRT no longer reliably representing response-inhibition efficacy. Here, we performed new analyses on behavioral and functional data from an fMRI version of the Stop-signal task to gauge the consequences of using different SSRT estimation approaches that are differentially prone to the influence of strategic response slowing. The results indicate that the SSRT estimation approach can dramatically change behavior-behavior correlations. Specifically, a correlation between the SSRT and Go-trial accuracy that was highly significant with one estimation approach, virtually disappeared for the other. Additional analyses indeed supported that this effect was related to strategic response slowing. Concerning brain-behavior correlations, only the left anterior insula was found to be significantly correlated with the SSRT within the set of areas tested here. Interestingly, this brain-behavior correlation differed little for the different SSRT-estimation procedures. In sum, the current results highlight that different SSRT-estimation procedures can strongly influence the distribution of SSRT values across subjects, which in turn can ramify into correlational analyses with other parameters.
Open Access
The time course of shape discrimination in the human brain.
(Neuroimage, 2013-02-15) Ales, Justin M; Appelbaum, L Gregory; Cottereau, Benoit R; Norcia, Anthony M
The lateral occipital cortex (LOC) activates selectively to images of intact objects versus scrambled controls, is selective for the figure-ground relationship of a scene, and exhibits at least some degree of invariance for size and position. Because of these attributes, it is considered to be a crucial part of the object recognition pathway. Here we show that human LOC is critically involved in perceptual decisions about object shape. High-density EEG was recorded while subjects performed a threshold-level shape discrimination task on texture-defined figures segmented by either phase or orientation cues. The appearance or disappearance of a figure region from a uniform background generated robust visual evoked potentials throughout retinotopic cortex as determined by inverse modeling of the scalp voltage distribution. Contrasting responses from trials containing shape changes that were correctly detected (hits) with trials in which no change occurred (correct rejects) revealed stimulus-locked, target-selective activity in the occipital visual areas LOC and V4 preceding the subject's response. Activity that was locked to the subjects' reaction time was present in the LOC. Response-locked activity in the LOC was determined to be related to shape discrimination for several reasons: shape-selective responses were silenced when subjects viewed identical stimuli but their attention was directed away from the shapes to a demanding letter discrimination task; shape-selectivity was present across four different stimulus configurations used to define the figure; LOC responses correlated with participants' reaction times. These results indicate that decision-related activity is present in the LOC when subjects are engaged in threshold-level shape discriminations.