Optogenetic tools for analyzing the neural circuits of behavior

In order to understand how the brain generates behaviors, it is important to be able to determine how neural circuits work together to perform computations. Because neural circuits are made of a great diversity of cell types, it is critical to be able to analyze how these different kinds of cell work together. In recent years, a toolbox of fully genetically encoded molecules has emerged that, when expressed in specific neurons, enables the electrical activity of the targeted neurons to be controlled in a temporally precise fashion by pulses of light. We describe this optogenetic toolbox, how it can be used to analyze neural circuits in the brain and how optogenetics is impacting the study of cognition.     

Psychophysics of the McGurk and other audiovisual speech integration effects

When the auditory and visual components of spoken audiovisual nonsense syllables are mismatched, perceivers produce four different types of perceptual responses, auditory correct, visual correct, fusion (the so-called McGurk effect), and combination (i.e., two consonants are reported). Here, quantitative measures were developed to account for the distribution of the four types of perceptual responses to 384 different stimuli from four talkers. The measures included mutual information, correlations, and acoustic measures, all representing audiovisual stimulus relationships. In Experiment 1, open-set perceptual responses were obtained for acoustic /bɑ/ or /lɑ/ dubbed to video /bɑ, dɑ, gɑ, vɑ, zɑ, lɑ, wɑ, eɑ/. The talker, the video syllable, and the acoustic syllable significantly influenced the type of response. In Experiment 2, the best predictors of response category proportions were a subset of the physical stimulus measures, with the variance accounted for in the perceptual response category proportions between 17% and 52%. That audiovisual stimulus relationships can account for perceptual response distributions supports the possibility that internal representations are based on modality-specific stimulus relationships.     

Emphatic inaccuracy in husband to wife aggression: The overattribution bias

Is husbands’ wife‐directed aggression related to unusual accuracy (hypersensitivity) or to bias (being likely to inappropriately infer criticism or rejection) when they infer women’s critical/rejecting thoughts and feelings? Results of a study using the empathic accuracy paradigm and signal detection analyses revealed that the greater the husbands’ bias to overattribute criticism and rejection to the thoughts and feelings of women they had never met, the more the husbands reported behaving in a verbally aggressive way toward their own wives. This finding discourages the conclusion that maritally aggressive men are uniquely provoked by their own female partners, and instead suggests that they are biased to overattribute criticism and rejection to women in general. The strength of this overattribution bias correlated negatively with the men’s accuracy in inferring the actual content of the women’s thoughts and feelings. On the other hand, the husbands’ thematic accuracy (their ability to accurately specify which of the stimulus women’s thoughts and feelings really were critical or rejecting) was associated with their self‐reported marital satisfaction.     

Measuring lexical diversity in children who stutter: application of vocd

There is growing but equivocal evidence that the language abilities of young children who stutter (CWS) may be depressed when compared to those of their fluent peers. In particular, the lexical skills of CWS have variously been reported to be weaker or stronger than comparison children in a number of recent studies. One source for such disagreement may be the measures used to compute lexical characteristics of these children's spoken conversations. In this study, we examined the concurrent validity of two measures of lexical diversity in spontaneous language samples, Type-Token Ratio (TTR) and the newly developed utility vocd (Malvern & Richards, 1997), using a standard test of expressive vocabulary as the comparison measure. Findings indicated that vocd values ("D") correlated well with standardized measures of expressive vocabulary, while TTR values did not. In addition, both the standardized measure and vocd revealed significantly poorer expressive lexical skills of CWS, whereas TTR analyses did not evidence this difference. Results are discussed in relation to the relative strength of vocd over TTR as a method for describing lexical characteristics of the spontaneous language samples of this population. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to (1) identify several common measures of conversational vocabulary and the strengths and weaknesses of each, and (2) compare the performance of the young CWS in this study to their normally fluent peers in terms of vocabulary performance on both formal and conversational measures of vocabulary.     

Biography becomes autobiography: distorting the subjective past

This work addresses whether creating a biographical sketch for a fictional adolescent can increase confidence that one personally experienced these details in adolescence (memory distortion) and whether susceptibility to such distortion (depends on whether adolescence is considered part of one's subjective past or subjective present. We divided the subjective past and present using the point at which a person experienced the last life event that changed his or her personality significantly. We operationalized the subjective past as events associated with the period before the last life-changing event and the subjective present as events associated with the period after that event. Participants' confidence in their own autobiographical memory increased after they wrote a brief story about a fictional character. This increase occurred only for those who considered adolescence to be part of their subjective past. These results indicate that subjective time (in addition to objective time) may be a valuable factor in determining who is susceptible to memory distortion. We discuss these findings in terms of familiarity attribution and source monitoring.     

Attention and size in a global/local task

Two-letter stimuli, consisting of one small letter inside a much larger one (in Experiments 1A, 1B, and 2) or inside a "blob" (in Experiment 3), were used to examine the role of size difference in global/local tasks. The small letter was placed at locations that avoided contour interactions. The results showed no identity interference, in that the specific identity of the large letter did not differentially affect identification of the small one. However, there was evidence of global advantage, in that the presence of a large letter hindered identification of the small one. The magnitude of the global advantage effect, as measured by the difference in performance between the small-single and small-embedded conditions, was largest (about 200 ms reaction time (RT) difference) when the large letters were the same as the small ones, lower (a 63 ms difference in Experiment IB, and 89 ms in Experiment 2) when the large letters were unrelated to the small ones, and lowest (a 25 ms difference) when the large stimuli were blobs. It is proposed that the amount of interference depends on the overlap between the features of the large stimuli, as a set, and those of the small ones, also as a set.     

When Home Is Where the Harm Is: Family Betrayal and Posttraumatic Outcomes in Young Adulthood

Research on institutional betrayal has found that institutional wrongdoing that fails to prevent or respond supportively to victims of abuse adds to the burden of trauma. In this two-study investigation with young adult university students, we demonstrated parallels between institutional betrayal and ways that families can fail to prevent or respond supportively to child abuse perpetrated by a trusted other, a phenomenon we call family betrayal (FB). In Study 1, psychometric analysis of a new FB questionnaire provided evidence of its internal consistency, unidimensionality, and convergent and discriminant validity. The majority (approximately 72%) of young adults abused in childhood reported a history of FB, with an average of 4.26 FB events (SD = 4.45, range 0–14). Consistent with betrayal trauma theory, Study 2 revealed that FB was 4× more likely to occur in relation to childhood abuse by someone very close to the victim (vs. non-interpersonal victimization), with a particularly strong effect for female participants. FB history predicted significant delay to disclosure of a self-identified worst traumatic event (η_p² = .017) and significant increases in dissociation (?R² = .05) and posttraumatic stress (?R² = .07) symptoms in young adulthood. Moreover, with FB in the regression models, only FB—not child abuse nor recent interpersonal victimization—predicted dissociation and clinically significant elevations in posttraumatic stress. Findings suggest that FB is a prevalent phenomenon among young adults abused as children and that it explains unique, clinically significant variance in posttraumatic distress, warranting increased attention from trauma researchers and clinicians.     

Impaired Health-Related Quality of Life in Children and Families Affected by Methylmalonic Acidemia

An understanding of health related quality of life (HRQoL) in children and families affected by methylmalonic acidemia (MMA) is important in planning counseling and therapeutic intervention. Liver transplantation (LT) is used as a treatment for MMA; however, its risks and benefits continue to be investigated. The purpose of this study was twofold: (1) to measure HRQoL in children and families affected by MMA using the Pediatric Quality of Life Inventory (PedsQL?) parent version, and (2) to assess the impact of LT on HRQoL by comparing LT and non-LT patient scores and free responses. Parents/caregivers reported lower scores on the majority of the PedsQL? scales as compared to samples of healthy children, children with solid organ transplants for indications other than MMA, and families affected by chronic conditions. Scores for children with MMA were lowest in school and social functioning and scores for families were lowest in worry and activity impairment. There were no significant differences in LT and non-LT patient scores on the PedsQL? scales. Our results document the negative impact of MMA on HRQoL.