Kara A Dyckman

Kara A Dyckman
University of Georgia | UGA · Department of Psychology

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31
Publications
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1,147
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Publications

Publications (31)
Article
Full-text available
Background Brain function in schizophrenia has been probed using saccade paradigms and functional magnetic resonance imaging, but little information exists about how changing task context impacts saccade related brain activation and behavioral performance. We recruited schizophrenia and comparison subjects to perform saccade tasks in differing cont...
Article
Full-text available
The ability to dynamically and rapidly adjust task performance based on its outcome is fundamental to adaptive, flexible behavior. Over trials of a task, responses speed up until an error is committed and after the error responses slow down. These dynamic adjustments serve to optimize performance and are well-described by the speed-accuracy trade-o...
Article
Objectives: To evaluate brain activation using functional magnetic resonance imaging (fMRI) and specifically, activation changes across time associated with practice-related cognitive control during eye movement tasks. Experimental design: Participants were engaged in antisaccade performance (generating a glance away from a cue) while fMR images...
Article
Cognitive control is required for correct antisaccade performance. High antisaccade error rates characterize certain psychiatric disorders, but can be highly variable, even among healthy groups. Antisaccade data were acquired from a large sample of healthy undergraduates, and error rate was quantified. Participants who reliably made few errors (goo...
Article
Full-text available
Background: Impaired ability to use contextual information to optimally prepare for tasks contributes to performance deficits in schizophrenia. We used magnetoencephalography and an antisaccade task to investigate the neural basis of this deficit. Methods: In schizophrenia patients and healthy control participants, we examined the difference in...
Chapter
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Saccades are rapid eye movements that move the eyes to a location of interest. Regions within posterior parietal cortex (PPC) have consistently shown activation in brain imaging studies of saccades, ostensibly reflecting shifts of visual attention and the transformation of sensory input into motor commands. Saccades range from the most basic reflex...
Article
Full-text available
Cognitive control is required for correct performance on antisaccade tasks, including the ability to inhibit an externally driven ocular motor response (a saccade to a peripheral stimulus) in favor of an internally driven ocular motor goal (a saccade directed away from a peripheral stimulus). Healthy humans occasionally produce errors during antisa...
Article
Anti and pro-saccade performance in single or mixed contexts was explored in a large sample of young adults (n=281). ANOVAs were first conducted to evaluate trial type, context and gender effects. A cluster analysis was then used to determine whether subgroups could be identified based on saccadic performance variables. Increased antisaccade errors...
Article
Full-text available
Recognizing errors and adjusting responses are fundamental to adaptive behavior. The error-related negativity (ERN) and error-related functional MRI (fMRI) activation of the dorsal anterior cingulate cortex (dACC) index these processes and are thought to reflect the same neural mechanism. In the present study, we evaluated this hypothesis. Although...
Article
Full-text available
Responding to errors is a critical first step in learning from mistakes, a process that is abnormal in schizophrenia. To gain insight into the neural and molecular mechanisms of error processing, we used functional MRI to examine effects of a genetic variant in methylenetetrahydrofolate reductase (MTHFR 677C>T, rs1801133) that increases risk for sc...
Article
Impaired antisaccade performance is a consistent cognitive finding in schizophrenia. Antisaccades require both response inhibition and volitional motor programming, functions that are essential to flexible responding. We investigated whether abnormal timing of hemodynamic responses (HDRs) to antisaccades might contribute to perseveration of ocular...
Data
Statistical maps of MTHFR 677C>T genotype effects in the contrast of antisaccade correct versus fixation at 4 s displayed on the inflated medial and lateral cortical surfaces. The dACC is outlined in green.
Data
Schematic depiction of the saccadic paradigm with idealized eye position traces. Saccadic trials lasted 4000 ms and began with an instructional cue at the center of the screen. For half of the participants, orange concentric rings were the cue for a prosaccade trial (a) and a blue “X” was the cue for an antisaccade trial (b). These cues were revers...
Article
Full-text available
Patients with schizophrenia exhibit deficient response monitoring as indexed by blunted activation of the dorsal anterior cingulate cortex (dACC) and functionally related regions during error commission. This pattern may reflect heritable alterations of dACC function. We examined whether the hypofunctional 677C>T variant in MTHFR, a candidate schiz...
Article
Full-text available
Reaction time variability across trials to identical stimuli may arise from both ongoing and transient neural processes occurring before trial onset. These processes were examined with dense-array EEG as humans completed saccades in a "gap" paradigm known to elicit bimodal variability in response times, including separate populations of "express" a...
Article
Full-text available
Patients with schizophrenia consistently show deficient performance on tasks requiring volitional saccades. We previously reported reduced fractional anisotropy in the white matter underlying right dorsal anterior cingulate cortex in schizophrenia, which, along with lower fractional anisotropy in the right frontal eye field and posterior parietal c...
Article
This review provides a summary of the contributions made by human functional neuroimaging studies to the understanding of neural correlates of saccadic control. The generation of simple visually guided saccades (redirections of gaze to a visual stimulus or pro-saccades) and more complex volitional saccades require similar basic neural circuitry wit...
Article
People with schizophrenia and their biological relatives have deficits in executive control processes such as inhibition and working memory as evidenced by performance abnormalities on antisaccade (AS) and ocular motor delayed response (ODR) tasks. The present functional magnetic resonance imaging (fMRI) study was conducted to investigate brain act...
Article
The present study evaluated the effect of context on behavior and brain activity during saccade tasks. FMRI and eye movement data were collected while 36 participants completed three runs in a block design: (1) fixation alternating with pro-saccades, (2) fixation alternating with anti-saccades, and (3) pro- alternating with anti-saccades. Two task-...
Article
Schizophrenia is characterized by executive functioning deficits, presumably mediated by prefrontal cortex dysfunction. For example, schizophrenia participants show performance deficits on ocular motor delayed response (ODR) tasks, which require both inhibition and spatial working memory for correct performance. The present functional magnetic reso...
Article
Full-text available
Past research indicates that social exclusion leads to self-control failure. The present research examined the neural substrates of this effect. Participants were randomly assigned to either a social exclusion (n=15) or control (n=15) condition. Self-control was assessed by having participants solve 180 moderately difficult math problems while meas...
Article
The temporal and spatial characteristics of brain activity preceding prosaccades and antisaccades were investigated using source reconstructions of 64-channel electroencephalography and 148-channel magnetoencephalography data. Stimulus-locked data showed early cuneus activity was stronger during antisaccades, and later occipital gyrus activity was...
Article
Full-text available
The ability to change behavior to adapt to the environment, known as behavioral plasticity, is an important part of daily life. In the present study subjects' performances on antisaccade tasks were manipulated by training them on one of three different eye movement tasks (antisaccade, prosaccade, and fixation). Thirty subjects were tested at three...
Article
Full-text available
The entire gamut of facial shapes has not been included in prior research investigating the perception of African American men’s facial attractiveness. The 10 facial shapes identified for African American men (elliptic, oval, reversed oval, round, rectangular, quadratic, rhombic, trapezium, inverted trapezium, and pentagonal) were examined in this...
Article
The purpose of the present study was to determine whether changes in brain function during saccadic tasks could be observed after participants practiced eye movement tasks for one week. Although the behavioral effects of practice were unclear, there were particular saccade-related brain areas that showed changes across time; not all changes were in...

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