Standard experimental paradigm designs and data exclusion practices in cognitive psychology can inadvertently introduce systematic "shadow" biases in participant samples.

Standard cognitive psychology research practices can introduce inadvertent sampling biases that reduce the reliability and generalizability of the findings. Researchers commonly acknowledge and understand that any given study sample is not perfectly generalizable, especially when implementing typical experimental constraints (e.g., limiting recruitment to specific age ranges or to individuals with normal color vision). However, less obvious systematic sampling constraints, referred to here as "shadow" biases, can be unintentionally introduced and can easily go unnoticed. For example, many standard cognitive psychology study designs involve lengthy and tedious experiments with simple, repetitive stimuli. Such testing environments may 1) be aversive to some would-be participants (e.g., those high in certain neurodivergent symptoms) who may self-select not to enroll in such studies, or 2) contribute to participant attrition, both of which reduce the sample's representativeness. Likewise, standard performance-based data exclusion efforts (e.g., minimum accuracy or response time) or attention checks can systematically remove data from participants from subsets of the population (e.g., those low in conscientiousness). This commentary focuses on the theoretical and practical issues behind these non-obvious and often unacknowledged "shadow" biases, offers a simple illustration with real data as a proof of concept of how applying attention checks can systematically skew latent/hidden variables in the included population, and then discusses the broader implications with suggestions for how to manage and reduce, or at a minimum acknowledge, the problem.

Evidence for a Spoken Word Lexicon in the Auditory Ventral Stream.

The existence of a neural representation for whole words (i.e., a lexicon) is a common feature of many models of speech processing. Prior studies have provided evidence for a visual lexicon containing representations of whole written words in an area of the ventral visual stream known as the visual word form area. Similar experimental support for an auditory lexicon containing representations of spoken words has yet to be shown. Using functional magnetic resonance imaging rapid adaptation techniques, we provide evidence for an auditory lexicon in the auditory word form area in the human left anterior superior temporal gyrus that contains representations highly selective for individual spoken words. Furthermore, we show that familiarization with novel auditory words sharpens the selectivity of their representations in the auditory word form area. These findings reveal strong parallels in how the brain represents written and spoken words, showing convergent processing strategies across modalities in the visual and auditory ventral streams.

Increases in symptoms associated with obsessive-compulsive disorder among university students during the COVID-19 pandemic.

OBJECTIVE: The long-term consequences of the COVID-19 pandemic on college students' mental health remains unknown. The current study explored self-reported Obsessive-Compulsive symptomatology among college student cohorts from pre-, peak-, and later-pandemic time points. PARTICIPANTS: Undergraduate college students (N = 524) who volunteered for course credit. METHODS: Self-report responses on the Dimensional Obsessive-Compulsive Scale (DOCS), which includes subscales for contamination, unacceptable thoughts, harm responsibility, and symmetry, were collected from November 29, 2016 through April 27, 2021 and assessed for differences between the pre-, peak-, and later-pandemic cohorts. RESULTS: Peak-pandemic responders reported higher symptomatology for contamination and unacceptable thoughts compared to pre-pandemic responders (and for pre- vs. later-pandemic for contamination), with no significant effects for symmetry or harm responsibility. CONCLUSIONS: Although the longer-term consequences of the COVID-19 pandemic on students remains unknown, a greater shift in college mental health services from prevention to assessing and addressing more immediate challenges may be necessary.

Conscientiousness protects visual search performance from the impact of fatigue.

Visual search-looking for targets among distractors-underlies many critical professions (e.g., radiology, aviation security) that demand optimal performance. As such, it is important to identify, understand, and ameliorate negative factors such as fatigue-mental and/or physical tiredness that leads to diminished function. One way to reduce the detrimental effects is to minimize fatigue itself (e.g., scheduled breaks, adjusting pre-shift behaviors), but this is not always possible or sufficient. The current study explored whether some individuals are less susceptible to the impact of fatigue than others; specifically, if conscientiousness, the ability to control impulses and plan, moderates fatigue's impact. Participants (N = 374) self-reported their energy (i.e., the inverse of fatigue) and conscientiousness levels and completed a search task. Self-report measures were gathered prior to completing the search task as part of a large set of surveys so that participants could not anticipate any particular research question. Preregistered linear mixed-effect analyses revealed main effects of energy level (lower state energy related to lower accuracy) and conscientiousness (more trait conscientiousness related to higher accuracy), and, critically, a significant interaction between energy level and conscientiousness. A follow-up analysis, that was designed to illustrate the nature of the primary result, divided participants into above- vs. below-median conscientiousness groups and revealed a significant negative relationship between energy level and accuracy for the below median, but not above-median, group. The results raise intriguing operational possibilities for visual search professions, with the most direct implication being the incorporation of conscientiousness measures to personnel selection processes.

A precise quantification of how prior experience informs current behavior.

Human behavior does not exist in a bubble-it is influenced by countless forces, including each individual's current goals, preexisting cognitive biases, and prior experience. The current project leveraged a massive behavioral data set to provide a data-driven quantification of the relationship between prior experience and current behavior. Data from two different behavioral tasks (a categorization task and a visual search task) demonstrated that prior history had a precise, systematic, and meaningful influence on subsequent performance. Specifically, the greater the evidence for (or against) all aspects of the current trial, the more (or less) efficient behavior was on that trial. The robust influence of prior experience was present for even distracting and likely unattended information. The ubiquity and consistency of the effect for features both related and unrelated to stimulus presence suggests a domain-general mechanism that increases the efficiency of behavior in contexts that match prior experience. These findings are theoretically important for understanding behavioral adaptation, experimentally powerful for directly addressing effects of previous trials when designing and analyzing research projects, and potentially useful for optimizing behavior in various applied contexts. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Moving Beyond the Keypress: As Technology Advances, so Should Psychology Response Time Measurements.

Decades of research in cognitive psychology have largely relied on simple key or button presses to quantify human behavior. While many valuable discoveries have been made, a richer response modality may reveal more information regarding the different processes that underlie complex human behavior. This study provides a proof of concept for using a touch-and-swipe response method to separate response time into two components to extract more meaningful behavioral insights. Across several analyses, the two components were consistently shown to be separable, independent measurements of behavior. Furthermore, evaluating these isolated response time components improved inferential power and clarity of behavioral patterns. The touch-and-swipe response method is simple and easy-to-use, and it shows promise for more accurately targeting mechanisms of interest.

Great expectations: minor differences in initial instructions have a major impact on visual search in the absence of feedback.

Professions such as radiology and aviation security screening that rely on visual search-the act of looking for targets among distractors-often cannot provide operators immediate feedback, which can create situations where performance may be largely driven by the searchers' own expectations. For example, if searchers do not expect relatively hard-to-spot targets to be present in a given search, they may find easy-to-spot targets but systematically quit searching before finding more difficult ones. Without feedback, searchers can create self-fulfilling prophecies where they incorrectly reinforce initial biases (e.g., first assuming and then, perhaps wrongly, concluding hard-to-spot targets are rare). In the current study, two groups of searchers completed an identical visual search task but with just a single difference in their initial task instructions before the experiment started; those in the "high-expectation" condition were told that each trial could have one or two targets present (i.e., correctly implying no target-absent trials) and those in the "low-expectation" condition were told that each trial would have up to two targets (i.e., incorrectly implying there could be target-absent trials). Compared to the high-expectation group, the low-expectation group had a lower hit rate, lower false alarm rate and quit trials more quickly, consistent with a lower quitting threshold (i.e., performing less exhaustive searches) and a potentially higher target-present decision criterion. The expectation effect was present from the start and remained across the experiment-despite exposure to the same true distribution of targets, the groups' performances remained divergent, primarily driven by the different subjective experiences caused by each groups' self-fulfilling prophecies. The effects were limited to the single-targets trials, which provides insights into the mechanisms affected by the initial expectations set by the instructions. In sum, initial expectations can have dramatic influences-searchers who do not expect to find a target, are less likely to find a target as they are more likely to quit searching earlier.

Prioritizing Health Care Solutions for Pressure Ulcers Using the Quality Function Deployment Process.

Reducing the incidence and morbidity of pressure ulcers remains a leading national priority in patient safety. However, the optimal strategy for a hospital or health system to address this safety goal is not straightforward given the number and complexity of available solutions. Leveraging techniques from systems engineering, such as the quality function deployment process, may provide a transparent and objective way to address this challenge. A detailed and practical application of quality function deployment is presented that demonstrates the value of applying engineering practices for prioritizing solutions for pressures ulcers specifically and can easily be adapted to other conditions.

A crash in visual processing: Interference between feedforward and feedback of successive targets limits detection and categorization.

The human visual system can detect objects in streams of rapidly presented images at presentation rates of 70 Hz and beyond. Yet, target detection is often impaired when multiple targets are presented in quick temporal succession. Here, we provide evidence for the hypothesis that such impairments can arise from interference between "top-down" feedback signals and the initial "bottom-up" feedforward processing of the second target. Although it is has been recently shown that feedback signals are important for visual detection, this "crash" in neural processing affected both the detection and categorization of both targets. Moreover, experimentally reducing such interference between the feedforward and feedback portions of the two targets substantially improved participants' performance. The results indicate a key role of top-down re-entrant feedback signals and show how their interference with a successive target's feedforward process determine human behavior. These results are not just relevant for our understanding of how, when, and where capacity limits in the brain's processing abilities can arise, but also have ramifications spanning topics from consciousness to learning and attention.

Correction to: How to correctly put the "subsequent" in subsequent search miss errors.

The following formatting changes to the figures and table need to be made in order to enhance readability.

How to correctly put the "subsequent" in subsequent search miss errors.

Visual search, finding targets among distractors, is theoretically interesting and practically important as it involves many cognitive abilities and is vital for several critical industries (e.g., radiology, baggage screening). Unfortunately, search is especially error prone when more than one target is present in a display (a phenomenon termed the satisfaction of search effect or the subsequent search miss effect). The general effect is that observers are more likely to miss a second target if a first was already detected. Unpacking the underlying mechanisms requires two key aspects in analysis and design. First, to speak to the "subsequent" nature of the effect, the analyses must compare performance on single-target trials to performance for a second target in dual-target displays after a first has been found. Second, the design must include single-target displays that are matched in difficulty to each dual-target display to enable fair comparisons. However, it is not clear that prior research has met these two standards simultaneously. Work from academic radiology has primarily used designs with well-matched single- and dual-target trials, but most employed analyses that do not focus solely on performance after a first target has been detected. Work from cognitive psychology has generally performed the correct analyses, but relied on unmatched single- and dual-target trials, introducing a confound that could distort the results. In the current paper, we demonstrate the impact of this confound in empirical data and provide a roadmap for proper study design and analyses.

A Woman in Her 30s With a History of Cervical Cancer Presents With Shortness of Breath and Pleuritic Chest Pain.

A woman in her 30s presented to the ED with a 3-month history of shortness of breath on exertion, dry cough, and pleuritic chest pain. A month ago, the patient was seen at an internal medicine clinic and was found to have a right pleural effusion. A thoracentesis revealed straw-colored fluid, a total nucleated cell count of 1,260 × 106/L, and a differential with neutrophils of 0.15, lymphocytes of 0.55, macrophages/monocytes of 0.19, and eosinophils of 0.10. Fluid cytology and culture were negative. The patient was presumed to have a parapneumonic effusion and treated empirically with antibiotics. However, she continued to have progressive symptoms, prompting her current visit to the ED. The patient was diagnosed with stage IIIB invasive cervical squamous cell carcinoma (SCC) approximately 7 months ago. MRI of the pelvis demonstrated a cervical mass with invasion of the right parametrial fat, but there was no evidence of uterine, vaginal, or lymph node involvement. A CT scan of the chest, abdomen, and pelvis was negative for distant metastases. The patient completed treatment with external beam radiation therapy and cisplatin chemotherapy 6 months ago. Three weeks prior to presentation to the ED, a repeat MRI pelvis showed no evidence of tumor progression and features consistent with posttreatment fibrotic changes.

There Is a "U" in Clutter: Evidence for Robust Sparse Codes Underlying Clutter Tolerance in Human Vision.

The ability to recognize objects in clutter is crucial for human vision, yet the underlying neural computations remain poorly understood. Previous single-unit electrophysiology recordings in inferotemporal cortex in monkeys and fMRI studies of object-selective cortex in humans have shown that the responses to pairs of objects can sometimes be well described as a weighted average of the responses to the constituent objects. Yet, from a computational standpoint, it is not clear how the challenge of object recognition in clutter can be solved if downstream areas must disentangle the identity of an unknown number of individual objects from the confounded average neuronal responses. An alternative idea is that recognition is based on a subpopulation of neurons that are robust to clutter, i.e., that do not show response averaging, but rather robust object-selective responses in the presence of clutter. Here we show that simulations using the HMAX model of object recognition in cortex can fit the aforementioned single-unit and fMRI data, showing that the averaging-like responses can be understood as the result of responses of object-selective neurons to suboptimal stimuli. Moreover, the model shows how object recognition can be achieved by a sparse readout of neurons whose selectivity is robust to clutter. Finally, the model provides a novel prediction about human object recognition performance, namely, that target recognition ability should show a U-shaped dependency on the similarity of simultaneously presented clutter objects. This prediction is confirmed experimentally, supporting a simple, unifying model of how the brain performs object recognition in clutter. SIGNIFICANCE STATEMENT: The neural mechanisms underlying object recognition in cluttered scenes (i.e., containing more than one object) remain poorly understood. Studies have suggested that neural responses to multiple objects correspond to an average of the responses to the constituent objects. Yet, it is unclear how the identities of an unknown number of objects could be disentangled from a confounded average response. Here, we use a popular computational biological vision model to show that averaging-like responses can result from responses of clutter-tolerant neurons to suboptimal stimuli. The model also provides a novel prediction, that human detection ability should show a U-shaped dependency on target-clutter similarity, which is confirmed experimentally, supporting a simple, unifying account of how the brain performs object recognition in clutter.

A quantitative link between face discrimination deficits and neuronal selectivity for faces in autism.

Individuals with Autism Spectrum Disorder (ASD) appear to show a general face discrimination deficit across a range of tasks including social-emotional judgments as well as identification and discrimination. However, functional magnetic resonance imaging (fMRI) studies probing the neural bases of these behavioral differences have produced conflicting results: while some studies have reported reduced or no activity to faces in ASD in the Fusiform Face Area (FFA), a key region in human face processing, others have suggested more typical activation levels, possibly reflecting limitations of conventional fMRI techniques to characterize neuron-level processing. Here, we test the hypotheses that face discrimination abilities are highly heterogeneous in ASD and are mediated by FFA neurons, with differences in face discrimination abilities being quantitatively linked to variations in the estimated selectivity of face neurons in the FFA. Behavioral results revealed a wide distribution of face discrimination performance in ASD, ranging from typical performance to chance level performance. Despite this heterogeneity in perceptual abilities, individual face discrimination performance was well predicted by neural selectivity to faces in the FFA, estimated via both a novel analysis of local voxel-wise correlations, and the more commonly used fMRI rapid adaptation technique. Thus, face processing in ASD appears to rely on the FFA as in typical individuals, differing quantitatively but not qualitatively. These results for the first time mechanistically link variations in the ASD phenotype to specific differences in the typical face processing circuit, identifying promising targets for interventions.

Feasibility of an ambulance-based stroke trial, and safety of glyceryl trinitrate in ultra-acute stroke: the rapid intervention with glyceryl trinitrate in Hypertensive Stroke Trial (RIGHT, ISRCTN66434824).

BACKGROUND AND PURPOSE: The practicalities of doing ambulance-based trials where paramedics perform all aspects of a clinical trial involving patients with ultra-acute stroke have not been assessed. METHODS: We performed a randomized controlled trial with screening, consent, randomization, and treatment performed by paramedics prior to hospitalization. Patients with probable ultra-acute stroke (<4 hours) and systolic blood pressure (SBP) >140 mm Hg were randomized to transdermal glyceryl trinitrate (GTN; 5 mg/24 hours) or none (blinding under gauze dressing) for 7 days with the first dose given by paramedics. The primary outcome was SBP at 2 hours. RESULTS: Of a planned 80 patients, 41 (25 GTN, 16 no GTN) were enrolled >22 months with median age [interquartile range] 79 [16] years; men 22 (54%); SBP 168 [46]; final diagnosis: stroke 33 (80%) and transient ischemic attack 3 (7%). Time to randomization was 55 [75] minutes. After treatment with GTN versus no GTN, SBP at 2 hours was 153 [31] versus 174 [27] mm Hg, respectively, with difference -18 [30] mm Hg (P=0.030). GTN improved functional outcome with a shift in the modified Rankin Scale by 1 [3] point (P=0.040). The rates of death, 4 (16%) versus 6 (38%; P=0.15), and serious adverse events, 14 (56%) versus 10 (63%; P=0.75), did not differ between GTN and no GTN. CONCLUSIONS: Paramedics can successfully enroll patients with ultra-acute stroke into an ambulance-based trial. GTN reduces SBP at 2 hours and seems to be safe in ultra-acute stroke. A larger trial is needed to assess whether GTN improves functional outcome. CLINICAL TRIAL REGISTRATION URL: http://www.controlled-trials.com/ISRCTN66434824/66434824. Unique identifier: 66434824.

The perceived health risks of indoor radon gas and overhead powerlines: a comparative multilevel approach.

Radon and overhead powerlines are two radiation risk cases that have raised varying levels of concern among the general public and experts. Despite both involving radiation-a typically feared and unseen health hazard-individuals' perceptions of the two risk cases may invoke rather different factors. We examined individual and geographic-contextual factors influencing public perceptions of the health risks of indoor radon gas and overhead powerlines in a comparative research design, utilizing a postal questionnaire with 1,528 members of the general public (response rate 28%) and multilevel modeling techniques. This study found that beliefs about the two risk cases mainly differed according to the level of "exposure"-defined here in terms of spatial proximity. We argue that there are two alternative explanations for this pattern of findings: that risk perception itself varies directly with proximity, or that risk is more salient to concerned people in the exposed areas. We also found that while people living in high radon areas are more concerned about the risks of indoor radon gas, they find these risks more acceptable and have more trust in authorities. These results might reflect the positive effects of successive radon campaigns in high radon areas, which may have raised awareness and concern, and at the same time may have helped to increase trust by showing that the government takes the health risks of indoor radon gas seriously, suggesting that genuine risk communication initiatives may have positive impacts on trust in risk management institutions.

Youth tobacco surveillance--United States, 2001-2002.

PROBLEM/CONDITION: Cigarette smoking is the leading preventable cause of death in the United States, accounting for approximately 440,000 deaths each year. The prevalence of cigarette smoking nationwide among high school students (grades 9-12) increased during the 1990s, peaking during 1996-1997, and then declined. Approximately 80% of tobacco users initiate use before age 18 years. An estimated 6.4 million children aged <18 years who are living today will die prematurely as adults because they began to smoke cigarettes during adolescence. The annual health-related economic cost associated with tobacco use exceeds 167 billion dollars. Because of these health and economic consequences, CDC has recommended that states establish and maintain comprehensive tobacco-control programs to reduce tobacco use among youth. REPORTING PERIOD: This report covers data collected during January 2001-December 2002. DESCRIPTION OF THE SYSTEM: The National Youth Tobacco Survey (NYTS) and state youth tobacco surveys (YTS) were developed to provide states with data to support the design, implementation, and evaluation of comprehensive tobacco-control programs. NYTS is representative of middle and high school students in the 50 states and the District of Columbia. During spring 2002, a total of 26,149 students in 246 schools completed NYTS questionnaires. Weighted data for the YTS were achieved by 13 states in 2001 and by 20 states in 2002; state sample sizes varied (range: 982-38,934). This report summarizes data from the 2002 NYTS and the 2001 and 2002 YTS. RESULTS AND INTERPRETATION: Findings from the 2002 NYTS indicate that current use of any tobacco product ranged from 13.3% among middle school students to 28.2% among high school students. Cigarette smoking was the most prevalent form of tobacco use, with 9.8% of middle school students and 22.5% of high school students reporting that they currently smoke cigarettes. Cigar smoking was the second most prevalent form of tobacco use, with 6.0% of middle school students and 11.6% of high school students reporting that they currently smoke cigars. Among current cigarette smokers, 41.8% of middle school students and 52.0% of high school students reported that they usually smoke Marlboro cigarettes. Black middle school and high school students who smoke were more likely to smoke Newport cigarettes than any other brand (58.3% and 66.8%, respectively). Among middle school students aged <18 years, 75.9% were not asked to show proof of age when they bought or tried to buy cigarettes, and 63.4% were not refused purchase because of their age. Among high school students aged <18 years, 58.5% were not asked to show proof of age when they bought or tried to buy cigarettes, and 60.6% were not refused purchase because of their age. Nearly half (49.6%) of middle school students and 62.1% of high school students who smoke reported a desire to stop smoking cigarettes, with 55.4% of middle school students and 53.1% of high school students reported having made at least one cessation attempt during the 12 months preceding the survey. Among students who have never smoked cigarettes, 21.3% of middle school students and 22.9% of high school students were susceptible to initiating cigarette smoking in the next year. Exposure to secondhand smoke (i.e., environmental tobacco smoke) was high. During the week before the survey, 1) 88.3% of middle school students and 91.4% of high school students who currently smoke cigarettes and 47.1% of middle school students and 53.3% of high school students who have never smoked cigarettes were in the same room with someone who was smoking cigarettes; 2) 81.7% of middle school students and 83.7% of high school students who currently smoke cigarettes and 31.5% of middle school students and 29.1% of high school students who have never smoked cigarettes rode in a car with someone who was smoking cigarettes; and 3) 71.5% of middle school students and 57.5% of high school students who currently smoke cigarettes and 33.3% of middle school students and 29.9% of high school students who have never smoked cigarettes lived in a home in which someone else smoked cigarettes. Media and advertising influence was also noted, with 58.1% of middle school students and 54.9% of high school students who currently use tobacco and 11.0% of middle school students and 13.7% of high school students who have never used tobacco reporting that they would wear or use an item with a tobacco company name or logo on it. Although 84.6% of middle school students and 91.2% of high school students had seen or heard antismoking commercials on television or radio, 89.9% of middle school students and 91.3% of high school students also had seen actors using tobacco on television or in the movies. PUBLIC HEALTH ACTIONS: Health and education officials use YTS and NYTS data to plan, evaluate, and improve national and state programs to prevent and control youth tobacco use. States can use these data in presentations to their state legislators to demonstrate the need for funding comprehensive tobacco-control programs, including tobacco cessation and prevention programs for youth.

Evaluating the efficacy of a mental models approach for improving occupational chemical risk protection.

Chemical risk protection in the workplace relies partly on informing workers about possible risks using material safety data sheets (MSDS). This article reports on phase 2 of a project (phase 1 reported in Cox et al.), which employed a mental models approach to improve on data sheets as communicative interventions for perchloroethylene in dry cleaning and rosin-based solder flux in the electronics industry within small businesses in the United Kingdom (small enterprises (SEs) < 25 employees in the workplace). It focuses on the efficacy of a multimethod evaluation strategy to assess (1) the capacity of a mental models approach to yield contextually relevant data for intervention design and (2) the effectiveness of the strategy itself in validating the mental models data. The evaluation was conducted using postal questionnaires and semi-structured verbal protocols to provide responses to the alternative intervention content and to prioritize risk messages. User discussion groups were then employed, particularly as a means of establishing whether contextual information could be obtained that would differ qualitatively from the kind elicited through individual (semi) structured methods. We conclude that the mental models approach as part of an iterative process including systematic multimethod evaluation is successful in supporting the design of relevant communications to the users of chemicals. The overall viability of communicative interventions in the context of health and safety in small businesses remains in question. Future research might aim to develop a more holistic approach to interventions in complex occupational contexts.

Aberrant myofibril assembly in tropomodulin1 null mice leads to aborted heart development and embryonic lethality.

Tropomodulin1 (Tmod1) caps thin filament pointed ends in striated muscle, where it controls filament lengths by regulating actin dynamics. Here, we investigated myofibril assembly and heart development in a Tmod1 knockout mouse. In the absence of Tmod1, embryonic development appeared normal up to embryonic day (E) 8.5. By E9.5, heart defects were evident, including aborted development of the myocardium and inability to pump, leading to embryonic lethality by E10.5. Confocal microscopy of hearts of E8-8.5 Tmod1 null embryos revealed structures resembling nascent myofibrils with continuous F-actin staining and periodic dots of alpha-actinin, indicating that I-Z-I complexes assembled in the absence of Tmod1. Myomesin, a thick filament component, was also assembled normally along these structures, indicating that thick filament assembly is independent of Tmod1. However, myofibrils did not become striated, and gaps in F-actin staining (H zones) were never observed. We conclude that Tmod1 is required for regulation of actin filament lengths and myofibril maturation; this is critical for heart morphogenesis during embryonic development.

Mice lacking Tropomodulin-2 show enhanced long-term potentiation, hyperactivity, and deficits in learning and memory.

Actin filaments control cell morphology and are essential to the growth of dendritic spines and the plasticity of hippocampal long-term potentiation (LTP). The length of these filaments is regulated in muscle and nonmuscle cell types by tropomodulins 1-4 (Tmod1-4), a family of proteins that cap the pointed ends of actin filaments. To investigate whether tropomodulins could play a role in synaptic plasticity, learning, memory, or behavior, we created mice lacking Tropomodulin-2 (Tmod2), which is highly expressed in neuronal structures. Tmod2(lacZ-/-) mice are viable and fertile and exhibit no gross morphological or anatomical abnormalities, but behavioral analysis found hyperactivity, reduced sensorimotor gating, and impaired learning and memory. Electrophysiological analysis revealed enhanced LTP in Tmod2(lacZ-/-) mice. These studies suggest that Tmod2 plays a role in behavior, learning, memory, and synaptic plasticity.