Personal growth in caregivers of persons with brain injury or multiple sclerosis.

An existing scale of personal growth in caregivers of people with multiple sclerosis (MS) was expanded for use with an acquired brain injury (ABI) population, and was modified following additional psychometric analyses. A cross-sectional online survey was administered to 315 caregiving partners of persons with MS and 310 family caregivers of persons with ABI. Principal component analysis (PCA) performed on the original 32-item instrument yielded a 4-component, 17-item solution with correlated subscales with solid psychometric properties. Subscales were labelled Appreciation, Positivity, Adjustment, and Spirituality. Secondary PCA conducted revealed three subscales (five items each) correlated moderately while the fourth, Spirituality, remained distinct. The sum of the three five-item subscales may serve as a total score. Reliability analysis yielded acceptable-to-high internal consistency. Comparisons of the PGS with existing instruments demonstrated its discriminant/convergent validity. Two kinds of latent class analyses were conducted on the 15-item PGS to identify three latent classes that spanned the neurologic groups, revealing that measurement invariance was held for the instrument in this sample. An instrument with sound psychometric properties was established, designed to assess personal growth in caregivers of individuals with ABI or MS. Future work should explore its value in other populations and as a metric of changes over time.

Frequency-domain analysis of transient visual evoked potentials in schizophrenia.

PURPOSE: Frequency-domain measures were applied to characterize neural deficits in individuals with schizophrenia using transient visual evoked potentials (tVEP). These measures were compared with conventional time-domain measures to elucidate underlying neurophysiological mechanisms and examine the value of frequency analysis. METHODS: Four frequency bands of activity identified in previous work were explored with respect to magnitude (spectral power), timing (phase), a combined measure, magnitude-squared coherence (MSC), and compared to amplitudes and times of prominent deflections in the response. RESULTS: Band 2 power/MSC (14-28 Hz) captured the major deflections in the waveform and its power predicted N75-P100 amplitude for patients and controls. Band 3 power/MSC (30-40 Hz) correlated highly with the earliest deflection (P60-N75), reflecting input to primary visual cortex (V1) and produced the largest magnitude effect. Phase of the 24th harmonic component predicted P100 peak time for patients and controls and yielded the largest group difference. Cluster analyses including time- and frequency-domain measures identified subgroups of patients with differential neurophysiological effects. A small but significant difference in visual acuity was found between groups that appears to be neurally based: Acuity (range 0.63-1.6) was not correlated with any tVEP measures in controls nor with input timing to V1 (P60 peak time) in patients, but was correlated with later tVEP measures in patients. All but two of the patients were on antipsychotic medication: Medication level (chlorpromazine equivalents) was correlated negatively with tVEP time measures and positively with certain magnitude measures yielding responses similar to controls at high levels. CONCLUSIONS: Overall, frequency-domain measures were shown to be objective and recommended as an alternative to conventional, subjective time-domain measures for analyzing tVEPs and in distinguishing between groups (patients vs. controls and patient subgroups). The findings implicated a loss of excitatory input to V1 in schizophrenia. Acuity as measured in the current study reflected disease status, and medication level was associated with improved tVEP responses. These novel tVEP techniques may be useful in revealing neurophysiological processes affected in schizophrenia and as a clinical tool.

Contrast sensitivity deficits in schizophrenia: A psychophysical investigation.

Individuals with schizophrenia have problems with visual contrast processing. The current study investigated contrast sensitivity (CS) in schizophrenia/schizoaffective disorder to elucidate the underlying neural mechanisms affected by this disorder and to identify critical testing conditions that distinguish individuals with the disorder from healthy individuals. Principal component analysis was applied to the data (N = 143) to separate responses from distinct visual pathways. Participants were 68 patients and 75 age-similar controls. CS was obtained using a forced-choice psychophysical paradigm with grating patterns of low to high spatial frequency presented at short and long durations. Linear mixed-effects models were used to examine differences in log CS with respect to group, duration, and stimulus condition. Lower CSs were found in patients compared to controls over all stimulus conditions with the magnitude of deficits dependent on both spatial frequency and stimulus duration. Log CSs to low and high spatial frequencies loaded onto separate principal components, supporting the existence of two psychophysical mechanisms, transient and sustained. Critical conditions were identified to tap each mechanism. Visual acuity was correlated moderately with log CS to high, but not low, spatial frequencies, and deficits found for acuity and CS to moderate/high spatial frequencies (4-21 cycles/degree) appear to reflect dysfunction in the sustained mechanism. CS deficits found at the lowest spatial frequency tested (0.5 cycles/degree) appear to reflect dysfunction in the transient mechanism. Both types of CS deficits may have diagnostic value and implications for social and neurocognitive deficits in this disorder.

The influence of trait mindfulness on depression in multiple sclerosis: potential implications for treatment.

PURPOSE: This study seeks to add to existing literature on depression and illness intrusiveness in chronic disorders by examining, (1) how the perceived intrusiveness of multiple sclerosis (MS) leads to depression, (2) and the mediating role trait mindfulness plays in this relationship METHODS: Participants (N = 755) were persons with MS (PwMS) recruited through the North American Research Committee on MS (NARCOMS) registry (a larger study). Participants completed the Illness Intrusiveness Ratings Scale, the Hospital Anxiety and Depression Scale and the Mindful Attention Awareness Scale. A mediation model assessed if trait mindfulness mediates the relationship between illness intrusiveness and depression RESULTS: Illness intrusiveness predicted trait mindfulness (a = - 4.54; p < .001), trait mindfulness predicted depression (b = - .04; p < .001); there was a direct effect of illness intrusiveness on depression (c' = 2.53; p < .001) and an indirect effect on depression (ab = .17, 95% BCa CI [.10, .25]) when trait mindfulness was in the model, which represented a medium size effect, R2med = .10 [95% CI .07, .14] CONCLUSION: Trait mindfulness mediates the relationship between illness intrusiveness and depression in PwMS. Providers could provide psychoeducation on the benefits of mindfulness and mindfulness-based interventions.

Emotion regulation after acquired brain injury: a study of heart rate variability, attentional control, and psychophysiology.

Primary objective: To examine the efficacy of heart rate variability biofeedback (HRV-BF) to treat emotional dysregulation in persons with acquired brain injury. Design: A secondary analysis of a quasi-experimental study which enrolled 13 individuals with severe chronic acquired brain injury participating in a community-based programme. Response-to-treatment was measured with two HRV resonance indices (low frequency activity [LF] and low frequency/high frequency ratio [LF/HF]). Main outcome: Behavior Rating Inventory of Executive Function-informant report (emotional control subscale [EC]). Results: Results show significant correlation between LF and EC with higher LF activity associated with greater emotional control; the association between LF/HF pre-post-change score and EC is not statistically significant. A moderation model, however, demonstrates a significant influence of attention on the relation between LF/HF change and EC when attention level is high, with an increase in LF/HF activity associated with greater emotional control. Conclusions: HRV-BF is associated with large increases in HRV, and it appears to be useful for the treatment of emotional dysregulation in individuals with severe acquired brain injury. Attention training may enhance an individual's emotional control.

Quantification and statistical analysis of the transient visual evoked potential to a contrast-reversing pattern: A frequency-domain approach.

Visual function is often assessed by recording transient visual evoked potentials to contrast reversal of spatial patterns (tVEP-CR). This technique relies on measurements of amplitudes and peak times of a few points in the time-domain waveform, which require subjective selection of appropriate time points in a possibly noisy waveform and ignores much of the informational content in the response. Here, we introduce a set of frequency-domain measures that capture the full content of the response. Magnitude-squared coherence is used to determine the significance and reliability of magnitude measures; estimates of time delay are based on frequency-domain phase measures. In Study 1, extensive testing of a small number of observers revealed response details, and in Study 2, testing of a larger sample verified the novel frequency-domain measures and demonstrated the validity of a short-duration technique to produce reliable tVEP-CRs. In addition, Study 2 revealed adaptation effects present under prolonged stimulation conditions. Principal component analyses provided evidence for six distinct frequency mechanisms, and comparisons with time-domain measures indicated that power in high-frequency bands may be used as objective measures of excitatory input to visual cortex. A middle-frequency band captures the major peaks in the tVEP-CR waveform, and its power is highly correlated with the standard peak-to-trough amplitude measure. These novel frequency-domain indices may serve as more precise and powerful tools to assess visual function in healthy and diseased states.

Accuracy of isolated-check visual evoked potential technique for diagnosing primary open-angle glaucoma.

PURPOSE: The aim of this study was to determine the diagnostic accuracy, sensitivity and specificity of isolated-check visual evoked potentials (icVEP) in primary open-angle glaucoma (POAG). METHODS: Ninety POAG patients and sixty-six healthy controls were recruited consecutively. All subjects underwent icVEP and visual field testing. Swept icVEP response functions were obtained by increasing contrast in six stimulus steps, recording the electroencephalogram synchronized to the stimulus display's frame rate and calculating the corresponding signal-to-noise ratio (SNR) of the response at the fundamental frequency to evaluate visual function. Depth of modulation of the check luminance was increased as follows: 2, 4, 8, 14, 22 and 32%, about an equal level of standing contrast, so that the pattern appeared and disappeared at a frequency of 10.0 Hz. SNR above 0.85 was deemed to be significant at the 0.1 level and SNR above 1 significant at the 0.05 level. RESULTS: The results show that SNR is contrast dependent. It significantly rose as contrast increased. The areas under receiver-operating-characteristic curves (AUCs) indicating classification accuracy for all POAG cases in comparison with normal subjects were 0.790 (sensitivity 91.1%, specificity 69.7%) with the cutoff SNR of 0.85, and 0.706 (sensitivity 95.6%, specificity 51.5%) with the cutoff SNR of 1. The AUC of early glaucoma cases (EG) in comparison with normal subjects was 0.801 (sensitivity 93.3%, specificity 69.7%) with the cutoff SNR of 0.85, and 0.717 (sensitivity 97.8%, specificity 51.5%) with the cutoff SNR of 1. CONCLUSION: icVEP has good diagnostic accuracy (high sensitivity and moderate specificity) in distinguishing early POAG patients from healthy subjects. It might be a promising device to use in conjunction with complementary functional and structural measures for early POAG detection.

Development and Validation of the State-Trait Inventory of Cognitive Fatigue in Community-Dwelling Older Adults.

OBJECTIVE: To develop and validate a subjective measure of cognitive fatigue-the State-Trait Inventory of Cognitive Fatigue-in community-dwelling older adults. DESIGN: Scale development and test construction. SETTING: Community-dwelling older adults enrolled in a longitudinal cohort aging study. PARTICIPANTS: Participants (N=175) were healthy, English-speaking, community-dwelling adults, age ≥65 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: State-Trait Inventory of Cognitive Fatigue total, cognitive fatigue, motivation, mental effort, and boredom summation scores for both state and trait forms. RESULTS: Principal component analysis yielded the expected 4 components for both state and trait forms: cognitive fatigue, mental effort, motivation, and boredom. All components had good reliability. There was good convergent validity as measured by the strong positive relation between cognitive fatigue and a subjective measure of general fatigue, even after controlling for depressive symptoms. Greater subjective cognitive fatigue was associated with worse performance on measures thought to be more sensitive to aspects of executive functioning. CONCLUSIONS: This study developed and established the psychometric properties of a new instrument for the subjective measurement of cognitive fatigue for use in community-dwelling older adults. The State-Trait Inventory of Cognitive Fatigue's relatively brief administration time (<10min; mean, 5.6±2.9) and strong psychometric properties support its utility in both research and clinical settings. Future studies should establish the psychometric properties of this scale in other populations and examine its predictive utility for relevant clinical outcomes.

The impact of sexual dysfunction on health-related quality of life in people with multiple sclerosis.

BACKGROUND: Sexual dysfunction is a prevalent symptom in multiple sclerosis (MS) that may affect patients' health-related quality of life (HrQoL). OBJECTIVE: The objective of this paper is to examine the impact of sexual dysfunction on HrQoL in a large national sample using The Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 (MSISQ-19). METHODS: Participants were recruited from a large MS registry, the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry. Participants self-reported demographic information and completed the Patient Determined Disease Steps (PDDS), MSISQ-19, and the Short Form-12 (SF-12). RESULTS: The study population included 6183 persons (mean age: 50.6, SD = 9.6; 74.7% female, 42.3% currently employed). Using multivariate hierarchical regression analyses, all variables excluding gender predicted both the physical component summary (PCS-12) and the mental component summary (MCS-12) of the SF-12. Scores on the MSISQ-19 uniquely accounted for 3% of the variance in PCS-12 scores while disability level, as measured by PDDS, accounted for 31% of the variance. Conversely, MSISQ-19 scores uniquely accounted for 13% of the variance in MCS-12 scores, whereas disability level accounted for less than 1% of the variance. CONCLUSION: In patients with MS, sexual dysfunction has a much larger detrimental impact on the mental health aspects of HrQoL than severity of physical disability.

The Relationship between Clinical and Psychophysical Assessments of Visual Perceptual Disturbances in Individuals at Clinical High Risk for Psychosis: A Preliminary Study.

This study investigated relations between a measure of early-stage visual function and self-reported visual anomalies in individuals at clinical high risk for psychosis (CHR-P). Eleven individuals at CHR identified via the Structured Interview for Psychosis-Risk Syndromes (SIPS) were recruited from a CHR-P research program in NYC. The sample was ~36% female, ranging from 16 to 33 years old (M = 23.90, SD = 6.14). Participants completed a contrast sensitivity task on an iPad with five spatial frequencies (0.41-13 cycles/degree) and completed the self-report Audio-Visual Abnormalities Questionnaire. Higher contrast sensitivity (better performance) to low spatial frequencies was associated with higher perceptual (r = 0.616, p = 0.044) and visual disturbances (r = 0.667, p = 0.025); lower contrast sensitivity to a middle spatial frequency was also associated with higher perceptual (r = -0.604, p = 0.049) and visual disturbances (r = -0.606, p = 0.048). This relation between the questionnaire and contrast sensitivity to low spatial frequency may be indicative of a reduction in lateral inhibition and "flooding" of environmental stimuli. The association with middle spatial frequencies, which play a critical role in face processing, may result in a range of perceptual abnormalities. These findings demonstrate that self-reported perceptual anomalies occur in these individuals and are linked to performance on a measure of early visual processing.

Comparison of psychophysical, electrophysiological, and fMRI assessment of visual contrast responses in patients with schizophrenia.

Perception has been identified by the NIMH-sponsored Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) group as a useful domain for assessing cognitive deficits in patients with schizophrenia. Specific measures of contrast gain derived from recordings of steady-state visual evoked potentials (ssVEP) have demonstrated neural deficits within the visual pathways of patients with schizophrenia. Psychophysical measures of contrast sensitivity have also shown functional loss in these patients. In the current study, functional magnetic resonance imaging (fMRI) was used in conjunction with ssVEP and contrast sensitivity testing to elucidate the neural underpinnings of these deficits. During fMRI scanning, participants viewed 1) the same low and higher spatial frequency stimuli used in the psychophysical contrast sensitivity task, at both individual detection threshold contrast and at a high contrast; and 2) the same stimuli used in the ssVEP paradigm, which were designed to be biased toward either the magnocellular or parvocellular visual pathway. Patients showed significant impairment in contrast sensitivity at both spatial frequencies in the psychophysical task, but showed reduced occipital activation volume for low, but not higher, spatial frequency at the low and high contrasts tested in the magnet. As expected, patients exhibited selective deficits under the magnocellular-biased ssVEP condition. However, occipital lobe fMRI responses demonstrated the same general pattern for magnocellular- and parvocellular-biased stimuli across groups. These results indicate dissociation between the fMRI measures and the psychophysical/ssVEP measures. These latter measures appear to have greater value for the functional assessment of the contrast deficits explored here.

Using a highly abbreviated California Verbal Learning Test-II to detect verbal memory deficits.

Multiple sclerosis (MS) is frequently accompanied by changes in verbal memory. We hypothesized that administering an abbreviated California Verbal Learning Test-II (CVLT-II) would detect verbal memory problems in MS accurately, thus serving as a potential screening tool. We performed receiver-operating-characteristic (ROC) analyses of three trials (trial 1, trial 2, and trial 1+2 combined) for raw data against standardized total scores. The results showed that at 1.5 standard deviations (SD) from the mean, the first two trials were 96.3% accurate, while at 2 SD from the mean, the first two trials combined were 97.5% accurate. We conclude that this study demonstrates than an abbreviated CVLT-II is a valid screening tool for verbal memory impairments.

The Multiple Sclerosis Intimacy and Sexuality Questionnaire -- re-validation and development of a 15-item version with a large US sample.

BACKGROUND: Sexual dysfunction is common in multiple sclerosis (MS) but reliable and valid measurement in this population is needed. OBJECTIVE: The objective of this research is to re-validate the Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 in a large US sample. METHODS: A total of 6300 MS patients from the NARCOMS registry completed the MSISQ-19. Unforced principal component analysis utilizing oblique rotation with Kaiser Normalization validated its construct validity. RESULTS: The scree plot supported a three-component solution, with 63% of total variance explained. The components mirrored the original validation study measuring primary, secondary, and tertiary sexual dysfunction. PCA suggested the scale could be shortened to 15 items, which were found to apply equally well to males and females (with one primary item specific for each sex). The components were moderately intercorrelated (Pearson rs ranged from 0.5 to 0.67). The secondary subscale correlated most highly with self-reported disability (r (6081) = 0.44, p < 0.001), whereas the tertiary subscale correlated most highly with psychological distress (r (5992) = -.37, p < 0.001). Cronbach's alpha for the total scale (0.92) and the subscales (primary, 0.87; secondary, 0.82; tertiary, 0.91) demonstrated good reliability. CONCLUSION: The revised 15-item MSISQ is a reliable and valid measure of sexual dysfunction in men and women with MS.

Posttraumatic growth, social support, and social constraint in hematopoietic stem cell transplant survivors.

OBJECTIVE: The relation between posttraumatic growth (PTG) and aspects of the social context, such as social support and social constraint, continues to be unclear in cancer survivors. Social cognitive processing theory is a useful framework for examining the effect of the social context on PTG. In theory, support interactions may either facilitate or hinder cognitive processing and thus lead to different PTG outcomes. The current study tested the hypothesis that emotional support and instrumental support would each explain a unique amount of the variance in PTG in distressed hematopoietic stem cell transplant (HSCT) survivors. Additionally, it was predicted that social constraint on cancer-related disclosure would be negatively associated with PTG. METHODS: Forty-nine distressed HSCT survivors with a spouse or partner completed the posttraumatic growth inventory and measures of social support received from their spouse/partner and social constraint from people close to them as part of a larger clinical trial. RESULTS: Both emotional and instrumental social support were positively correlated with PTG, and social constraint on disclosure was not associated with PTG. Contrary to hypotheses, instrumental support was the only unique social contextual predictor of PTG. CONCLUSIONS: The results of this study highlight the importance of examining the effects of subtypes of social support on PTG separately. Findings are discussed in the context of the cognitive (i.e., processing of the traumatic event) versus non-cognitive (i.e., buffering stress) pathways between the social context and PTG. Future research directions are presented.

Heart rate variability biofeedback, executive functioning and chronic brain injury.

PRIMARY OBJECTIVE: To determine if individuals with brain injury can modify heart rate variability (HRV) through biofeedback and, if so, enhance its pattern to improve emotional regulation and problem-solving ability. DESIGN: A quasi-experimental design with repeated measures was employed. Thirteen individuals aged 23-63 years with severe brain injury (13-40 years post-onset) participating in a community-based programme were enrolled. MAIN OUTCOMES: Response-to-treatment was measured with HRV indices, Behavior Rating Inventory of Executive Function (BRIEF-A-Informant) and attention/problem-solving tests. RESULTS: At post-treatment, HRV indices (Low Frequency/High Frequency [LF/HF] and coherence ratio) increased significantly. Increased LF/HF values during the second-half of a 10-minute session were associated with higher attention scores. Participants who scored better (by scoring lower) in informant ratings at pre-treatment had highest HRV scores at post-treatment. Accordingly, at post-treatment, families' ratings of participants' emotional control correlated with HRV indices; staffs' ratings of participants' working memory correlated with participants' HRV indices. Self-ratings of the BRIEF-A Task Monitoring scale at post-treatment correlated with family ratings at pre-treatment and post-treatment. CONCLUSIONS: Results demonstrate an association between regulation of emotions/cognition and HRV training. Individuals with severe, chronic brain injury can modify HRV through biofeedback. Future research should evaluate the efficacy of this approach for modifying behavioural problems.

Age-related differences in the severity of sexual dysfunction symptoms and psychological distress in individuals with multiple sclerosis.

BACKGROUND: Sexual dysfunction (SD) is a common symptom for many with multiple sclerosis (MS). However, SD research in general appears to often overlook young adults within their samples, which can be a major issue for better understanding and treatment for the MS population. Few studies have compared age-related differences in distress in response to physical disability. Research has also found that many people diagnosed with MS do not discuss any SD struggles with their providers. The present study hopes to see whether age-related differences exist in the reporting of the levels of primary, secondary, and tertiary SD, as defined by subscale scores of the Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 (MSISQ-19), and amount of distress, as defined by the 12-Item Short Form Health Survey (SF-12)'s Mental Component Summary (MCS-12). Additionally, we hope to determine if there are any age-related or sex-related differences in help-seeking behaviors for SD. METHODS: Study participants were recruited from the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry. Participants completed the MSISQ-19, SF-12, and Patient Determined Disease Steps (PDDS), provided demographic information, and responded if they received medical or psychological treatment for SD. Study participants were 5815 respondents (Mage = 51 years, SD = 9.63, 75 % female, 30 % having attained a high school diploma, 35 % scoring "advanced disability" on the PDDS). Young adult (19-39 years), middle adult (40-64 years), and mature adult (65-older) were compared on SD. RESULTS: Linear mixed effects modeling revealed that the MSISQ-19 subscale scores were significantly predicted by secondary SD (t = 2.48, p < .13). Young adult participants had the lowest primary SD (M = 13.87, 95 % CI [13.13, 14.61]) when compared to mature adult (M = 14.12, 95 % CI [13.27, 14.97]) and middle adult participants (M = 14.44, 95 % CI [14.21, 14.66]), though none were statistically significant. Mature adults had the lowest secondary SD (M = 16.50, 95 % CI [15.65, 17.35]), a statistically significant difference from the middle adults (M = 18.20, 95 % CI [17.97, 18.42]) and young adults (M = 18.91, 95 % CI [18.17, 19.65]). Mature adults had the lowest tertiary symptoms (M = 10.12, 95 % CI [9.27, 10.96]), followed by young adults (M = 12.23, 95 % CI [11.48, 12.97]), and middle adults (M = 11.65, 95 % CI [11.43, 11.88]), though none were statistically significant. Hierarchical multiple regressions found that age had the most significant impact on SD. When SF-12 MCS-12 was added, linear mixed effects did not reveal any statistically significant results between the age groups and SD levels. In contrast, hierarchical multiple regressions found that SF-12 MCS-12 scores had the most significant impact on SD. There were significant age-related and sex-related differences in help-seeking behaviors in those who sought psychological counseling as opposed to medical treatment for SD. CONCLUSION: Our study has highlighted the importance of clinicians assessing for SD and psychological distress within their patients and to consider potential differences in symptom presentations of age groups to better address their unique needs.

The spatial contrast sensitivity function and its neurophysiological bases.

Contrast processing is a fundamental function of the visual system, and contrast sensitivity as a function of spatial frequency (CSF) provides critical information about the integrity of the system. Here, we used a novel iPad-based instrument to collect CSFs and fitted the data with a difference of Gaussians model to investigate the neurophysiological bases of the spatial CSF. The reliability of repeat testing within and across sessions was evaluated in a sample of 22 adults for five spatial frequencies (0.41-13 cycles/degree) and two temporal durations (33 and 500 ms). Results demonstrate that the shape of the CSF, lowpass versus bandpass, depends on the temporal stimulus condition. Comparisons with previous psychophysical studies and with single-cell data from macaques and humans indicate that the major portion of the CSF, spatial frequencies >1.5 cycles/degree regardless of temporal condition, is determined by a 'sustained' mechanism (presumably parvocellular input to primary visual cortex [V1]). Contrast sensitivity to the lowest spatial frequency tested appears to be generated by a 'transient' mechanism (presumably magnocellular input to V1). The model fits support the hypothesis that the high spatial frequency limb of the CSF reflects the receptive field profile of the center mechanism of the smallest cells in the parvocellular pathway. These findings enhance the value of contrast sensitivity testing in general and increase the accessibility of this technique for use by clinicians through implementation on a commercially-available device.

Objective frequency analysis of transient visual evoked potentials in autistic children.

Visual evoked potentials (VEPs) provide a means to examine neural mechanisms in autism with high temporal resolution. Conventional VEP analysis relies on subjective inspection of a few points (peaks and troughs) in the time-domain waveform. The current study applied power spectral analysis and magnitude-squared coherence (MSC) statistics (frequency-domain measures) to VEPs recorded during 1-minute runs and with a recently developed short-duration technique that allow for objective examination of the responses (Zemon & Gordon, European Journal of Neuroscience, 2018, 48, 1765-1788) from nonautistic and autistic children. Results indicate that, for both groups, early time-domain measures (P60 , N75 , P100 ) are highly correlated with middle- and high-frequency (14-28 and 30-48 Hz, respectively) mechanisms, and late measures are highly correlated with a low-frequency (6-12 Hz) mechanism. One frequency-domain measure (power in the middle-frequency band) is capable of predicting the key amplitude measure (N75 -P100 ) with high accuracy. MSC and power measures were combined to yield separate measures of signal and noise strength to evaluate alternate hypotheses in autism. Linear mixed-effects modeling demonstrated selective differences in early time-domain and middle-to-high frequency-domain measures in autistic children as compared to nonautistic children given both recording techniques, implicating weaker excitatory input to the cortex. Receiver-operating-characteristic curve analysis showed predictive diagnostic accuracy for middle- and high-frequency bands based on MSC. These findings support the value of frequency analysis measures (power spectral analysis and MSC) in the objective examination of neural differences in autism. LAY SUMMARY: Visual evoked potentials (VEPs) are used to assess neural mechanisms. Typically, VEPs are analyzed by subjective examination of time-series waveforms; but here objective techniques were applied to quantify VEP frequency components to investigate neural differences between autistic and nonautistic children. The objective measures demonstrate group differences in brain function that point to weaker excitatory input to the cortex in autism.

Handedness and Cognition in Multiple Sclerosis: Potential Indications for Hemispheric Vulnerability.

BACKGROUND: Multiple sclerosis (MS) affects over 2.5 million individuals worldwide, yet much of the disease course is unknown. Hemispheric vulnerability in MS may elucidate part of this process but has not yet been studied. The current study assessed neuropsychological functioning as it relates to hemispheric vulnerability in MS. METHODS: Verbal IQ, as measured by verbal comprehension index (VCI), nonverbal IQ, as measured by perceptual reasoning index (PRI) and memory acquisition were compared in right-handed (dextral) and non-right-handed (non-dextral) persons with MS (PwMS). RESULTS: Linear mixed-effects modeling indicated a significant main effect of handedness, F(1, 195.35) = 3.95, p = .048, for a composite measure of VCI, PRI, and memory acquisition, with better performance for dextral PwMS. In examining differences for specific neuropsychological measures, the largest effect size between dextral and non-dextral participants was seen in PRI (d = 0.643), F(1,341) = 12.163, p = .001. No significant interaction effect between handedness and IQ was found, F(3, 525.60) = 0.75, p = .523. CONCLUSIONS: Dextral PwMS perform better than non-dextral PwMS when assessing neuropsychological performance for memory and IQ combined. Results are suggestive of increased vulnerability in the left brain to the pathological process of MS.

Visual Evoked Potential Abnormalities in Phelan-McDermid Syndrome.

OBJECTIVE: The current study used visual evoked potentials (VEPs) to examine excitatory and inhibitory postsynaptic activity in children with Phelan-McDermid syndrome (PMS) and the association with genetic factors. PMS is caused by haploinsufficiency of SHANK3 on chromosome 22 and represents a common single-gene cause of autism spectrum disorder (ASD) and intellectual disability. METHOD: Transient VEPs were obtained from 175 children, including 31 with PMS, 79 with idiopathic ASD, 45 typically developing controls, and 20 unaffected siblings of children with PMS. Stimuli included standard and short-duration contrast-reversing checkerboard conditions, and the reliability between these 2 conditions was assessed. Test-retest reliability and correlations with deletion size were explored in the group with PMS. RESULTS: Children with PMS and, to a lesser extent, those with idiopathic ASD displayed significantly smaller amplitudes and decreased beta and gamma band activity relative to TD controls and PMS siblings. Across groups, high intraclass correlation coefficients were obtained between standard and short-duration conditions. In children with PMS, test-retest reliability was strong. Deletion size was significantly correlated with P60-N75 amplitude for both conditions. CONCLUSION: Children with PMS displayed distinct transient VEP waveform abnormalities in both time and frequency domains that might reflect underlying glutamatergic deficits that were associated with deletion size. A similar response pattern was observed in a subset of children with idiopathic ASD. VEPs offer a noninvasive measure of excitatory and inhibitory neurotransmission that holds promise for stratification and surrogate endpoints in ongoing clinical trials in PMS and ASD.