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Daniel J. Simmonds
University of Pittsburgh
Developmental psychologyPsychologyNeuroscienceCognitionWorking memory
15Publications
12H-index
1,961Citations
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Publications 15
Newest
#1Brenden Tervo-Clemmens (University of Pittsburgh)H-Index: 4
#2Daniel J. Simmonds (University of Pittsburgh)H-Index: 12
Last. Beatriz Luna (University of Pittsburgh)H-Index: 9
view all 8 authors...
Abstract Background Retrospective neuroimaging studies have suggested an association between early cannabis onset and later neurocognitive impairment. However, these studies have been limited in their ability to distinguish substance use risk factors from cannabis-induced effects on neurocognition. We used a prospective cohort design to test whether neurocognitive differences preceded cannabis onset (substance use risk model) and if early cannabis use was associated with poorer neurocognitive de...
5 CitationsSource
#1Andrew Lynn (Brown University)H-Index: 2
#2Aarthi Padmanabhan (Stanford University)H-Index: 13
Last. Kirsten O'Hearn (University of Pittsburgh)H-Index: 19
view all 7 authors...
Face recognition abilities improve between adolescence and adulthood over typical development (TD), but plateau in autism, leading to increasing face recognition deficits in autism later in life. Developmental differences between autism and TD may reflect changes between neural systems involved in the development of face encoding and recognition. Here, we focused on whole-brain connectivity with the fusiform face area (FFA), a well-established face-preferential brain region. Older children, adol...
13 CitationsSource
#1Brenden Tervo-Clemmens (University of Pittsburgh)H-Index: 4
#2Daniel J. Simmonds (University of Pittsburgh)H-Index: 12
Last. Beatriz Luna (University of Pittsburgh)H-Index: 9
view all 6 authors...
Abstract Given prior reports of adverse effects of cannabis use on working memory, an executive function with a protracted developmental course during adolescence, we examined associations between developmental patterns of cannabis use and adult working memory (WM) processes. Seventy-five adults with longitudinal assessments of cannabis use (60 with reported use, 15 with no reported use) and prenatal drug exposure assessment completed a spatial WM task during fMRI at age 28. All subjects passed ...
8 CitationsSource
#1Daniel J. Simmonds (University of Pittsburgh)H-Index: 12
#2Michael N. Hallquist (PSU: Pennsylvania State University)H-Index: 25
Last. Beatriz Luna (University of Pittsburgh)H-Index: 9
view all 3 authors...
Abstract Working memory (WM), the ability to hold information on-line to guide planned behavior, improves through adolescence in parallel with continued maturation of critical brain systems supporting cognitive control. Initial developmental neuroimaging studies with one or two timepoints have provided important though varied results limiting our understanding of which and how neural systems change during this transition into mature WM. In this study, we leverage functional magnetic resonance im...
18 CitationsSource
#1Daniel J. SimmondsH-Index: 12
#2Michael N. Hallquist (University of Pittsburgh)H-Index: 25
Last. Beatriz LunaH-Index: 54
view all 4 authors...
White matter (WM) continues to mature through adolescence in parallel with gains in cognitive ability. To date, developmental changes in human WM microstructure have been inferred using analyses of cross-sectional or two time-point follow-up studies, limiting our understanding of individual developmental trajectories. The aims of the present longitudinal study were to characterize the timing of WM growth and investigate how sex and behavior are associated with different developmental trajectorie...
161 CitationsSource
Your brain is the control center of your body; every movement, thought, and feeling that you have starts in your brain. But how does the brain do this? The work in the brain is done by neurons, a type of cell that looks like a tree with lots of branches going in all directions (look at the left side of Figure 1 to see what a neuron looks like). Thoughts and actions happen when different neurons “talk” to each other. In fact, there are neurons all over your body that get information about the wor...
Source
#1Rebecca Vaurio (ICSCI: Kennedy Krieger Institute)H-Index: 3
#2Daniel J. Simmonds (University of Pittsburgh)H-Index: 12
Last. Stewart H. Mostofsky (ICSCI: Kennedy Krieger Institute)H-Index: 59
view all 3 authors...
One of the most consistent findings in children with ADHD is increased moment-to-moment variability in reaction time (RT). The source of increased RT variability can be examined using ex-Gaussian analyses that divide variability into normal and exponential components and Fast Fourier transform (FFT) that allow for detailed examination of the frequency of responses in the exponential distribution. Prior studies of ADHD using these methods have produced variable results, potentially related to dif...
149 CitationsSource
#1Stewart H. Mostofsky (Johns Hopkins University)H-Index: 59
#2Stephanie K. Powell (ICSCI: Kennedy Krieger Institute)H-Index: 1
Last. James J. Pekar (Johns Hopkins University)H-Index: 53
view all 6 authors...
Although motor deficits are common in autism, the neural correlates underlying the disruption of even basic motor execution are unknown. Motor deficits may be some of the earliest identifiable signs of abnormal development and increased understanding of their neural underpinnings may provide insight into autism-associated differences in parallel systems critical for control of more complex behaviour necessary for social and communicative development. Functional magnetic resonance imaging was use...
284 CitationsSource
#1Charles Chong-Hwa Hong (Johns Hopkins University)H-Index: 2
#2James C O Harris (Johns Hopkins University)H-Index: 28
Last. James J. Pekar (Johns Hopkins University)H-Index: 53
view all 12 authors...
We studied the neural correlates of rapid eye movement during sleep (REM) by timing REMs from video recording and using rapid event-related functional MRI. Consistent with the hypothesis that REMs share the brain systems and mechanisms with waking eye movements and are visually-targeted saccades, we found REM-locked activation in the primary visual cortex, thalamic reticular nucleus (TRN), ‘visual claustrum’, retrosplenial cortex (RSC, only on the right hemisphere), fusiform gyrus, anterior cing...
68 CitationsSource
#1Ericka L. Wodka (JHUSOM: Johns Hopkins University School of Medicine)H-Index: 14
#2Daniel J. Simmonds (ICSCI: Kennedy Krieger Institute)H-Index: 12
Last. Stewart H. Mostofsky (JHUSOM: Johns Hopkins University School of Medicine)H-Index: 59
view all 4 authors...
To examine the impact of interstimulus “jitter” (i.e., randomization of the interval between successive stimulus events) on response control during continuous task performance, 41 healthy adults completed four go/no-go tasks that were identical except for interstimulus interval (ISI) jitter: a 0% jitter task with a fixed (1,000-ms) ISI, a 10% jitter task with an ISI range of 900–1,100 ms, a 30% jitter task with an ISI range of 700–1,300 ms, and a 50% jitter task with an ISI range of 500–1,500 ms...
22 CitationsSource
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