Attention refers to that critical aspect of cognitive and neural functioning that allows us to focus on and respond to the most important aspects of our environment. Transient lapses of attention lead to inefficient learning, distracted driving, and neglect of ongoing needs, and the involuntary capture of attention to stimuli that trigger cravings relates to the difficulties in overcoming addiction. Enhancing the ability to control attention is therefore potentially important across a wide range of situations.

In Dr. Joseph Hopfinger’s lab, functional magnetic resonance imaging (fMRI) is used to identify the neural structures involved in voluntary and involuntary attention, and electroencephalogram (EEG) recordings are used to better understand the timing of these activities. A critical part of the network involved in attentional control is the posterior parietal area of the brain, especially in the right hemisphere. Indeed, patients with damage to parietal areas in the right hemisphere often show a “disengage” deficit, in which they are especially impaired at reorienting their attention to their impaired visual field after they’ve been engaged in their “good” visual field. In a recent study, Dr. Hopfinger’s lab stimulated the parietal region of the brain in healthy young adults to investigate if boosting activity there could enhance the same process that is impaired in patients with damage to that area.

The ability to safely and noninvasively stimulate localized regions of the brain is an exciting new direction in brain research. The new Neurostimulation Core lab (co-directed by Dr. Hopfinger and Dr. Charlotte Boettiger) allows investigators to perform some of the most promising types of this stimulation – transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES). Neural activity is known to occur at multiple oscillatory frequencies, and in Dr. Hopfinger’s recent work, they used a variant of tES called transcranial alternating current stimulation (tACS) to target not just the brain region of interest, but to also stimulate it at the specific frequencies that EEG studies have suggested may be most involved with specific functions of attention. In a recent study (Hopfinger et al., 2017, in Cognitive Neuroscience), Dr. Hopfinger and graduate student Jonathan Parsons stimulated the posterior parietal area of brain at two frequencies, a slower pattern called alpha (~10Hz) and a faster pattern called gamma (~40 Hz), each proposed to be associated with cognitive functions.

The results showed that gamma stimulation enhanced participants’ ability to reorient attention. Specifically, after their right parietal cortex was stimulated, subjects were significantly faster to disengage attention from its current focus and reorient to a new location where the target suddenly appeared. Critically, this was not simply a general function of any stimulation, because stimulating the exact same area but at the slower frequency (10 Hz) produced no effect on task performance. These findings go beyond previous fMRI and patient research by providing new evidence of the specific patterns of neural activity within the parietal lobe that affect the mental functions of disengaging and reorienting attention. Whereas parietal damage impairs these functions, stimulation within the gamma frequency range enhances it.

Furthermore, the same stimulation parameters that produced effects on voluntary attention produced no effects on involuntary attention capture. This relates to other fMRI research in Dr. Hopfinger’s lab which indicates that the brain’s attention network is differentially engaged across the hemispheres for voluntary attention compared to involuntary attention (Meyer et al., 2018, in Neuropsychologia). With medical student Jake Bowling, Dr. Hopfinger’s lab is currently using connectivity modeling of fMRI results to show that the direction and strength of connections between the parietal and frontal attentional control regions are different across the hemispheres for voluntary vs. involuntary attention. These lines of research aim to reveal the precise brain mechanisms by which individuals fall prey to distraction and how they regain control over their mind’s eye.

Dr. Joseph Hopfinger is a Professor in the Cognitive Psychology Program within the Department of Psychology and Neuroscience at UNC Chapel Hill. He is also the leader of the cross-program Human Neuroimaging Group in the Department of Psychology and Neuroscience. His work studies the cognitive processes and neural mechanisms of attention, distraction, and selective perception using a multi-methodological approach. To learn more about Dr. Hopfinger and his research, visit him online.


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