Alfredo Sklar

Alfredo Sklar

Doctor of Philosophy

About

23
Publications
1,081
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
227
Citations
Featured research
Article
Full-text available
Background Impairments in selective attention and their neurophysiologic concomitants early in the course of psychotic illness remain relatively understudied. Our recent data provided evidence for disruptions in the attention-related electrophysiological responses among individuals following their first psychotic break (FESz). Specifically, FESz exhibited reduced amplitudes of the N2pc component compared to healthy controls (HC) during a target detection task. The present investigation additionally used the magnetoencephalography (MEG) data that had been simultaneously recorded during selective attention task performance to identify disruptions in source-resolved cortical regions underlying the N2pc impairment. Methods MEG and EEG were simultaneously recorded from 22 first-episode schizophrenia spectrum (FESz) and 22 healthy control (HC) individuals during two target detection tasks that required different degrees of top-down attentional control; pop-out and visual search. MEG and EEG sensor locations were coregistered with structural MRI scans for each participant and the boundary element method was used to model the forward solution. The inverse solution for cortical activity contributing to the N2pc signal (275 – 325ms post stimulus) was then derived using the noise covariance matrix calculated from the baseline period of each trial. BA7, BA39, and BA37 were selected a priori as regions of interests (ROIs) based on previous investigations of N2pc sources. Average activity during the N2pc time window was compared between groups using a 2 (task condition) x 2 (group) x 3 (ROI) ANOVA. Results A significant interaction between group and task condition was observed (F1,42=5.3, p=.03). HC exhibited marginally increased activity during pop-out compared to FESz (t42=1.86, p=.07) despite a statistically equivalent level of activity during visual search (t42=-0.86, p=.39). There were no main effects of group (p=.54), task condition (p=.90), or ROI (p=.94). Nor were there interactions between ROI and group (p=.81) or ROI and task (p=.16). Whereas no correlations between ROI activity and N2pc were observed among FESz (p’s>.05), larger BA37 during visual search activity was associated with larger N2pc scalp amplitudes in HC (r=-.65, p=.001). Discussion In contrast to the simple group difference in N2pc amplitude recorded from the scalp, examination of the cortical dynamics contributing to this response revealed a differential effect of task condition between groups. FESz exhibited reduced activity relative to HC on target pop-out trials compared to those requiring a top-down, serial search of potential target stimuli. While this finding appears counterintuitive, it may reflect a hyperfocusing of attention on distractor stimuli in our FESz group recently described in a study of individuals with schizophrenia. This mechanism would explain the relative preservation of attention-related cortical activity in FESz during a task with increased distractor interference. The difference between our sensor-level N2pc results based on EEG recordings and our source-level cortical activity derived from simultaneously recorded EEG and MEG speaks to the importance of utilizing complementary imaging modalities to enrich our understanding of processes involved in complex cognitive functions.
Article
Full-text available
Unlabelled: ABSTRACT. Objective: Despite substantial attention being paid to the health benefits of moderate alcohol intake as a lifestyle, the acute effects of alcohol on psychomotor and working memory function in older adults are poorly understood. Method: The effects of low to moderate doses of alcohol on neurobehavioral function were investigated in 39 older (55-70 years; 15 men) and 51 younger (25-35 years; 31 men) social drinkers. Subjects received one of three randomly assigned doses (placebo, .04 g/dl, or .065 g/dl target breath alcohol concentration). After beverage consumption, they completed the Trail Making Test Parts A and B and a working memory task requiring participants to determine whether probe stimuli were novel or had been presented in a preceding set of cue stimuli. Efficiency of working memory task performance was derived from accuracy and reaction time measures. Results: Alcohol was associated with poorer Trail Making Test Part B performance for older subjects. Working memory task results suggested an Age × Dose interaction for performance efficiency, with older but not younger adults demonstrating alcohol-related change. Directionality of change and whether effects on accuracy or reaction time drove the change depended on the novelty of probe stimuli. Conclusions: This study replicates previous research indicating increased susceptibility of older adults to moderate alcohol-induced psychomotor and set-shifting impairment and suggests such susceptibility extends to working memory performance. Further research using additional tasks and assessing other neuropsychological domains is needed. (J. Stud. Alcohol Drugs, 75, 870-879, 2014).
Conference Paper
Full-text available
Introduction: Despite an extensive literature documenting the health benefits of a moderate drinking lifestyle, the acute effects of moderate consumption and how they change across the lifespan have remained understudied. Our previous report (Sklar et al., 2013) observed an increased sensitivity to alcohol among older drivers on basic components of driving using a simple driving scenario. The present study extended these findings using multiple scenarios that more closely represented real-world driving situations to measure adverse driving events.Methods:36 older (M=60.3, SD=3.9) and 36 younger (M=27.3, SD=2.5) healthy moderate drinkers participated. Under a no alcohol condition, subjects completed a~20 minute simulated driving task (baseline). The drive consisted of 23 events (e.g., intersections, crosswalks, etc.) spanning three scenarios of increasing complexity (i.e. rural, small town, and city). On a subsequent day, subjects returned to the laboratory, received one of three randomly assigned alcohol doses intended to pro-duce breath alcohol concentrations of either 0.0% (placebo), 0.04% (low), and 0.065%(moderate),and repeated the driving exercise. Dependent variables included the number of a) crashes, b) excursions (i.e., roadside and centerline crossings), c) speed limit exceedances, and d) failures to stop at red lights. Results: Older adults were involved in more crashes, excursions, and ran more red lights than their younger counterparts (p’s<0.05) at baseline. Following beverage consumption, individuals in the moderate dose group committed more lane excursions than placebo when baseline performance was included as a covariate (p=0.02). An interaction between age and dose was observed for red light stop failures with older adults in the moderate dose group running more red lights than younger adults at the same dose level (p=0.01).Conclusion: These data provide further evidence for the impairing effects of moderate alcohol consumption on driving performance. They also suggest a differential age effect of alcohol on driving, although this interaction was observed for only one of the dependent variables. Future analyses examining setting complexity and its interactions with age and alcohol are of particular interest in light of previous research exploring age and alcohol effects on cognitive load and distractibility using simulated driving tasks https://doi.org/10.1111/acer.12451
Article
Full-text available
Evidence from a growing body of literature suggests that alcohol, even at moderate-dose levels, disrupts the ability to ignore distractors. However, little work has been done to elucidate the neural processes underlying this deficit. The present study was conducted to determine if low-to-moderate alcohol doses affect sensory gating, an electrophysiological phenomenon believed to reflect the pre-attentive filtering of irrelevant sensory information. Sixty social drinkers were administered one of three doses intended to produce breath alcohol concentrations of 0.0 % (placebo), 0.04 % (i.e., low dose), and 0.065 % (i.e., moderate dose). A paired-click paradigm consisting of 100 pairs of identical tones (S1 and S2) was used to assess sensory gating. Amplitudes of P50, N100, and P200 auditory evoked potentials (AEPs) were used to calculate gating difference (S1-S2) and ratio (S2/S1) scores. The moderate alcohol dose significantly decreased P50 and N100 gating relative to placebo. Comparisons between the difference and ratio scores helped characterize the gating mechanisms affected at these stages of information processing. Alcohol did not alter P200 sensory gating. These data suggest that alcohol disrupts pre-attentional sensory-filtering processes at breath alcohol concentrations (BrACs) below the current 0.08 % legal limit. Future studies should perform a combined assessment of sensory gating and selective attention to better understand the relationship between these two alcohol-induced deficits.
Article
Full-text available
There is a substantial body of literature documenting the deleterious effects of both alcohol consumption and age on driving performance. There is, however, limited work examining the interaction of age and acute alcohol consumption. The current study was conducted to determine if moderate alcohol doses differentially affect the driving performance of older and younger adults. Healthy older (55-70) and younger (25-35) adults were tested during a baseline session and again following consumption of one of three beverages [0.0 % (placebo), 0.04 % or 0.065 % target breath alcohol concentration]. Measures of driving precision and average speed were recorded. Older adults performed more poorly on precision driving measures and drove more slowly than younger adults at baseline. After controlling for baseline performance, interactions between alcohol and age were observed following beverage consumption on two measures of driving precision with older adults exhibiting greater impairment as a result of alcohol consumption. These data provide evidence that older adults may be more susceptible to the effects of alcohol on certain measures of driving performance. An investigation of mechanisms accounting for alcohol's effects on driving in older and younger adults is required. Further evaluation using more complex driving environments is needed to assess the real-world implication of this interaction.

Publications

Publications (23)
Article
Introduction Aberrant network connectivity is a core deficit in schizophrenia and may underlie many of its associated cognitive deficits. Previous work in first-episode schizophrenia spectrum illness (FESz) suggests preservation of working memory network function during low-load conditions with dysfunction emerging as task complexity increases. Thi...
Article
Cognitive impairments account for significant morbidity in schizophrenia and are present at disease onset. Controlled processes are particularly susceptible and may contribute to pervasive selective attention deficits. The present study assessed fronto-parietal attention network (FPAN) functioning during cue presentation on a visual search task in...
Article
Background Knowledge is lacking regarding deficits in selective attention and their underlying biological mechanisms during early stages of schizophrenia. The present study examined the N2pc, a neurophysiological index of covert spatial attention, and its cortical sources at first psychotic episode in the schizophrenia spectrum (FESz). Methods Neu...
Article
Impairments in early-stage visual processing are observed in chronic psychosis. However, their presence, localization within the brain, and contribution to cognitive symptoms remain less well established early in disease course. The present study utilized magnetoencephalography (MEG) to examine sensory responses within primary visual cortex (V1). M...
Article
Full-text available
Background Impairments in selective attention and their neurophysiologic concomitants early in the course of psychotic illness remain relatively understudied. Our recent data provided evidence for disruptions in the attention-related electrophysiological responses among individuals following their first psychotic break (FESz). Specifically, FESz ex...
Article
A limited number of publications have documented the effects of acute alcohol administration among older adults. Among these, only a few have investigated sex differences within this population. The current project examined the behavioral effects of acute low- and moderate-dose alcohol on 62 older (ages 55-70) male and female, healthy, light to mod...
Article
Full-text available
Unlabelled: ABSTRACT. Objective: Despite substantial attention being paid to the health benefits of moderate alcohol intake as a lifestyle, the acute effects of alcohol on psychomotor and working memory function in older adults are poorly understood. Method: The effects of low to moderate doses of alcohol on neurobehavioral function were inves...
Conference Paper
Full-text available
Introduction: Despite an extensive literature documenting the health benefits of a moderate drinking lifestyle, the acute effects of moderate consumption and how they change across the lifespan have remained understudied. Our previous report (Sklar et al., 2013) observed an increased sensitivity to alcohol among older drivers on basic components of...
Article
Full-text available
Evidence from a growing body of literature suggests that alcohol, even at moderate-dose levels, disrupts the ability to ignore distractors. However, little work has been done to elucidate the neural processes underlying this deficit. The present study was conducted to determine if low-to-moderate alcohol doses affect sensory gating, an electrophysi...
Article
Full-text available
There is a substantial body of literature documenting the deleterious effects of both alcohol consumption and age on driving performance. There is, however, limited work examining the interaction of age and acute alcohol consumption. The current study was conducted to determine if moderate alcohol doses differentially affect the driving performance...
Article
Full-text available
Background: Studies exploring differential effects of acute alcohol consumption on younger and older adults are lacking within the field of alcohol research, especially those using moderate doses. Previous studies addressing this question have tended to use complex behavioral tasks too broad to isolate specific neurocognitive processes affected by...
Conference Paper
Full-text available
Background. Although acute behavioral effects of alcohol intoxication are well studied, less is known about the effects of small doses of alcohol. This pilot study was conducted to examine the relationship between subjective intoxication, alcohol dose, and neurobehavioral performance. Methods. Healthy, nonsmoking community-dwelling subjects (n = 8,...
Article
This study provides a comprehensive expression analysis for the entire matrix metalloproteinase (MMP) gene family during the process of epithelial resurfacing following corneal abrasion injury in the mouse. The mRNA levels for all known MMP genes expressed in mouse, the related enzyme ADAM-10, and the known tissue inhibitors of metalloproteinases (...
Conference Paper
Purpose: Nicotine use is prevalent among treatment-seeking substance abusers. Recent work in our lab suggests that acute nicotine may serve to “normalize” the stress response as reflected in salivary cortisol levels obtained after laboratory-based psychological stressors (Gilbertson, et al, 2011). Previous work (e.g., Errico, et al, 2002) suggested...
Conference Paper
Attentional deficits in abstinent alcoholics are well characterized, particularly with regard to cognitive efficiency (conceptualized in terms of speed/accuracy tradeoffs). Of interest, cortisol responsivity is known to be compromised in this population. Current work from our laboratory suggests that in alcoholics receiving active transdermal nicot...
Article
This study examined the effects of interpersonal similarity on vicarious error processing. We predicted that high similarity between self and other would predict increased neural responsiveness to the other's errors, based on the assumption that experience is more strongly shared when it involves similar others. Participants observed a confederate...

Network

Cited By