My research focuses on the cognitive and neural mechanisms of attentional control and their breakdown.
How do we decide what we pay attention to? How do we ignore irrelevant information? How does past experience shape these processes? How are these process impaired by aging and disease?
These are a few of the questions guiding my research program, and I attempt to answer them using an array of behavioral and neuroscientific methods. In addition, I'm interested in other topics such as understanding the organization of prefrontal cortex and how we can use this knowledge to understand and improve cognitive control.
The role of bottom-up factors top-down attentional control
Along with my colleagues, I have demonstrated that perceptual competition between items in a search display determines the strength of top-down control over irrelevant information processing (Roper, Cosman, & Vecera, 2013), even when irrelevant information is highly salient (Cosman & Vecera, 2009, 2010a, 2010b). Similarly, we have shown that during perceptual grouping an individual’s ability to selectively ignore irrelevant visual information depends on whether that information is ‘grouped’ into the same object as relevant visual information (Cosman & Vecera, 2010, 2012). This suggests that early, ‘bottom-up’ perceptual processes can directly influence the effectiveness of top-down control, and ongoing work is examining how deficits in perceptual competition contribute to attention issues in psychiatric populations.
The role of learning in top-down attentional control
A large portion of my work has focused on how long-term learning and memory systems enable us to better suppress the processing of irrelevant information. I have argued that attentional suppression relies on the gradual ‘tuning’ of the visual system to aspects of a task and its context; in other words, we learn to control attention (Cosman & Vecera, 2010a, Cosman & Vecera, 2013a, 2014; Vecera, Cosman, et al., 2014). For example, implicit learning of contingencies between targets, distractors and their defining features (e.g., their shape or color) is both necessary and sufficient to effectively ignore distracting, task-irrelevant information (Cosman & Vecera, 2013a, 2014). Further, ERP indices of distractor suppression (the distractor positivity, or Pd) are present only when observers learn that specific features define a task-irrelevant distractor (Cosman & Woodman, 2015, VSS). Finally, learning-dependent control is absent in amnesic patients with bilateral medial temporal lobe damage (Cosman & Vecera, 2013b) even at short delays (Cosman, under revision), suggesting that traditional associative learning and memory systems play a critical role in top-down attentional control.
Comparative studies of attentional control
A large portion of my current work is focused on establishing homologies in the behavioral and electrophysiological characteristics of attentional control across humans and non-human primates. These homologies provide a basis for studying the neurophysiological foundations of behavioral and EEG markers of attention, improving their interpretability and clinical utility in humans. I have demonstrated that macaque monkeys exhibit an ERP component related to distractor suppression during visual search (the Pd component referenced above) nearly identical to that observed in humans (Cosman, Schall, & Woodman, 2014a). Importantly, I have shown through simultaneous recording of single unit responses in multiple regions of the prefrontal cortex (frontal eye field (FEF), dorsal premotor cortex (PMd)) that a cascade of inhibitory processes lead to the suppression of salient distractor items preceding the onset of the Pd. This suggests that a distributed prefrontal network may be responsible for generating distractor suppression effects observed in both behavior and the surface EEG (Cosman, Schall, & Woodman, 2014 SfN; Cosman et al., 2015 SfN).
Causally manipulating top-down control: tDCS
On the basis of the psychophysical and neurophysiological findings outlined above, I have begun to use trasncranial direct-current stimulation in conjunction with EEG to causally explore the neural mechanisms of attention in humans. In short, tDCS uses surface electrodes to connect the brain to an electrical circuit, allowing weak currents to reach the cortex and alter neuronal excitability. We have shown using concurrent tDCS/EEG that following stimulation of FEF in humans, there is little influence on general visual search behavior or the neural correlates of target selection (measured by the N2pc). However, there is a marked reduction in the processing of task-irrelevant distractors directly following stimulation, suggesting a selective influence of FEF stimulation on distractor suppression (Cosman, Atreya, & Woodman, 2015; Cosman, Atreya, & Woodman, in prep).
Causally manipulating top-down control: Focused Ultrasound
In conjunction with colleagues in the Vanderbilt Department of Radiology (Charles Caskey) and Psychology (Wolf Zinke), I have helped to develop a non-human primate model for ultrasound-based neuromodulation. Whereas tDCS electrically modulates neural excitability, transcranial focused ultrasound (tFUS) uses sound waves to mechanically alter excitability. It also provides a much more focal site of stimulation than tDCS (~2mm vs. 2cm). We are currently one of only a handful of groups in the world with a primate model of tFUS, and are using tFUS in conjunction with EEG and single unit recordings in prefrontal cortex to better understand how different parameters (e.g., intensity, duration) change the behavioral and neural effects of tFUS on attentional and motor processes. In preliminary work, we have shown that tFUS centered on frontal eye field can speed saccade production in both simple detection tasks and more difficult visual search tasks, and this speeding is reflected in both sensory and attention-related EEG responses.
These are a few of the questions guiding my research program, and I attempt to answer them using an array of behavioral and neuroscientific methods. In addition, I'm interested in other topics such as understanding the organization of prefrontal cortex and how we can use this knowledge to understand and improve cognitive control.
The role of bottom-up factors top-down attentional control
Along with my colleagues, I have demonstrated that perceptual competition between items in a search display determines the strength of top-down control over irrelevant information processing (Roper, Cosman, & Vecera, 2013), even when irrelevant information is highly salient (Cosman & Vecera, 2009, 2010a, 2010b). Similarly, we have shown that during perceptual grouping an individual’s ability to selectively ignore irrelevant visual information depends on whether that information is ‘grouped’ into the same object as relevant visual information (Cosman & Vecera, 2010, 2012). This suggests that early, ‘bottom-up’ perceptual processes can directly influence the effectiveness of top-down control, and ongoing work is examining how deficits in perceptual competition contribute to attention issues in psychiatric populations.
The role of learning in top-down attentional control
A large portion of my work has focused on how long-term learning and memory systems enable us to better suppress the processing of irrelevant information. I have argued that attentional suppression relies on the gradual ‘tuning’ of the visual system to aspects of a task and its context; in other words, we learn to control attention (Cosman & Vecera, 2010a, Cosman & Vecera, 2013a, 2014; Vecera, Cosman, et al., 2014). For example, implicit learning of contingencies between targets, distractors and their defining features (e.g., their shape or color) is both necessary and sufficient to effectively ignore distracting, task-irrelevant information (Cosman & Vecera, 2013a, 2014). Further, ERP indices of distractor suppression (the distractor positivity, or Pd) are present only when observers learn that specific features define a task-irrelevant distractor (Cosman & Woodman, 2015, VSS). Finally, learning-dependent control is absent in amnesic patients with bilateral medial temporal lobe damage (Cosman & Vecera, 2013b) even at short delays (Cosman, under revision), suggesting that traditional associative learning and memory systems play a critical role in top-down attentional control.
Comparative studies of attentional control
A large portion of my current work is focused on establishing homologies in the behavioral and electrophysiological characteristics of attentional control across humans and non-human primates. These homologies provide a basis for studying the neurophysiological foundations of behavioral and EEG markers of attention, improving their interpretability and clinical utility in humans. I have demonstrated that macaque monkeys exhibit an ERP component related to distractor suppression during visual search (the Pd component referenced above) nearly identical to that observed in humans (Cosman, Schall, & Woodman, 2014a). Importantly, I have shown through simultaneous recording of single unit responses in multiple regions of the prefrontal cortex (frontal eye field (FEF), dorsal premotor cortex (PMd)) that a cascade of inhibitory processes lead to the suppression of salient distractor items preceding the onset of the Pd. This suggests that a distributed prefrontal network may be responsible for generating distractor suppression effects observed in both behavior and the surface EEG (Cosman, Schall, & Woodman, 2014 SfN; Cosman et al., 2015 SfN).
Causally manipulating top-down control: tDCS
On the basis of the psychophysical and neurophysiological findings outlined above, I have begun to use trasncranial direct-current stimulation in conjunction with EEG to causally explore the neural mechanisms of attention in humans. In short, tDCS uses surface electrodes to connect the brain to an electrical circuit, allowing weak currents to reach the cortex and alter neuronal excitability. We have shown using concurrent tDCS/EEG that following stimulation of FEF in humans, there is little influence on general visual search behavior or the neural correlates of target selection (measured by the N2pc). However, there is a marked reduction in the processing of task-irrelevant distractors directly following stimulation, suggesting a selective influence of FEF stimulation on distractor suppression (Cosman, Atreya, & Woodman, 2015; Cosman, Atreya, & Woodman, in prep).
Causally manipulating top-down control: Focused Ultrasound
In conjunction with colleagues in the Vanderbilt Department of Radiology (Charles Caskey) and Psychology (Wolf Zinke), I have helped to develop a non-human primate model for ultrasound-based neuromodulation. Whereas tDCS electrically modulates neural excitability, transcranial focused ultrasound (tFUS) uses sound waves to mechanically alter excitability. It also provides a much more focal site of stimulation than tDCS (~2mm vs. 2cm). We are currently one of only a handful of groups in the world with a primate model of tFUS, and are using tFUS in conjunction with EEG and single unit recordings in prefrontal cortex to better understand how different parameters (e.g., intensity, duration) change the behavioral and neural effects of tFUS on attentional and motor processes. In preliminary work, we have shown that tFUS centered on frontal eye field can speed saccade production in both simple detection tasks and more difficult visual search tasks, and this speeding is reflected in both sensory and attention-related EEG responses.
