Traumatic brain injury
Effects of sports-related concussion on the neurocognitive-linguistic system
The short- and long-term effects of sports-related concussions remain a growing concern. Although the majority of college athletes' symptoms and cognitive deficits typically recover within 1-2 weeks post-concussion, findings from our lab (and others) used ERPs to demonstrate persistent changes to the functional neural networks underlying attention (Ledwidge & Molfese, 2016) and working memory (Hudac, Cortesa, Ledwidge & Molfese, 2017) years following injury. However, a lack of difference in neuropsychological abilities between athletes with and without a history of concussion begs the question: What is the clinical utility of ERPs if behavioral markers of cognition are not affected?
Recently, we suggested that investigations studying the association between sports-related concussion and language abilities are warranted (Ledwidge, in press). Sparse research has considered this avenue, which is surprising given the number of studies demonstrating persistent language deficits following non-sports-related concussion. Efficient and accurate language comprehension involves the interaction between both lexical, cognitive, (and often social) mechanisms. Consequently, it is possible that behavioral and electrophysiological assessments of language comprehension provide naturalistic tools to examine recovery from sports-related concussion
We are collaborating with the BW Department of Communication Disorders to study changes to the cognitive-linguistic system during concussion recovery in college athletes. We are collecting both functional measures as well as recording ERPs during both comprehension and cognitive inhibition. Our goal is to successfully chart the time course of recovery of cognition and language in this population to better inform clinical best practices for concussion management and intervention.
Cognitive and Emotional Brain Responses in Children and Adolescents
In this study we’re recording event-related brain potentials (ERPs) in children and adolescents 7-17 years of age to examine typically developing cognitive and emotional processing. The findings from this study will guide our future work in investigating how these brain responses may change after pediatric concussion. As shown in the picture
to the right, we
record EEG while children/adolescents view
pictures that vary in emotional
valence (i.e., negative, neutral, positive).
Before we could study the LPP brain response, we first
normed a set of images on emotional valence and arousal
children/adolescents and were also “parent-approved.”
The images we selected are from the Nencki
Affective Picture System (NAPS), which is a set
of standardized, realistic images
(e.g., animals; see right image ), that elicit
emotional responses (Marchewka et al., 2013).
These images had never been normed in
children/adolescents. In an online study, parents
determined which pictures were appropriate for
their children to view. Then the children rated each picture
on emotional valence (e.g., negative,neutral, positive) using
the Self-Assessment Manikin (SAM; Bradley & Lang, 1994; see image below). Through this study, we normed standardized a set of 60 images: 30 which elicited positive emotions in children/adolescents and 30 which were neutral (Ledwidge et al., unpublished).
Previous literature has shown that mild traumatic brain injuries (mTBIs) may affect ERP markers of emotional-cognition in adults (Ma ̈ki-Marttunen et al., 2015). However, this has yet to be demonstrated in pediatric mTBI/concussion. In our study, we seek to establish that our set of parent-approved pictures replicates previous literature which showed that children’s brains elicit the LPP to emotional stimuli (Cuthbert et al., 2000; Hajcak and Olvet, 2008; Hajcak & Dennis, 2009). Our future work aims to use the LPP as a marker to study cognitive-emotional changes after concussion in children/adolescents.
Researchers adjusting an EEG net
Example NAPs image
Example of SAM scale used to assess valence
Adult Cognition and Language
Contextual ambiguity resolution during discourse comprehension
Our understanding of the meaning being portrayed within a conversation or discourse changes to each instance of a new semantic item. However, when the topic of a conversation is ambiguous, we must actively search for and identify the meaning/purpose that interlocultors or narrators are attempting to portray. This ambiguity extends beyond single words but rather encompasses the broader discourse context. We are using ERPs to study how the brain resolves this contextual ambiguity. Furthermore, is this process distinct from that which involves the change/update of an existing context?
Preliminary results from this study suggest that the Late Anterior Positivity ("Frontal post-N400 positivity") fluctuates to coherent words that partially resolve contextual ambiguity. In contrast, greater P600 amplitudes are recorded to coherent, but unexpected words within a known, existing context.
Smartphone-induced divided attention
The literature is rich in its demonstrations of the distracting properties of your cell-phone when used while driving. It turns out that humans are not as good at multi-tasking as we think. In fact, the term "multi-tasking" is a misnomer, as we instead switch between tasks with the performance on each task decreasing as a function of the number of tasks being performed.
The social aspects of smartphones (e.g., texting, notifications) have the capacity to provide us with potentially limitless positive reinforcement. The Motivated Cognition Model (Lang, 2006) demonstrates that we allocate greater attentional resources to stimuli we are motivated to engage in, such as those which provide positive reinforcement (e.g., cell phones). And as long our phones are turned on, there is always the opportunity to receive this gratification. This study is the first to examine if and how the mere presence of a smartphones alters ERP markers of attention.
The competition between emotional and spatial attention
Through this project we seek to understand the attentional competition between emotional and spatial information. From Posner's (1980) work (And others) we know that targets presented in locations (e.g., left side of screen) that were correctly cued by a preceding arrow (pointed left) are processes quicker than when there was a mismatch between cue and target. Follow up work from Mangun and Hillyard (1991) demonstrated this attentional facilitation by recording a greater N100 ERP to correctly cued targets.
We've adapted the Posner (1980) cueing task and instead are using averted faces (eye gaze left, right) crossed with emotional expression (negative, positive, neutral) as cues for the location of a forthcoming target. Since these cues carry both emotional and spatial information, ERPs recorded to post-cue targets will allow us to establish the attentional competition between them. The image below is an example of a valid cue-target trial.
We suspect that when an emotional face (e.g., happy, sad) validly cues the target location (e.g., eye gaze to left side, target location presented on the left), we will observe a smaller N1 amplitude to the target compared to when the valid face cue had a neutral expression. In ERP-ing the facial cue as well,dDifferences in late positive potential (LPP) amplitude to emotional faces (relative to neutral) would empirically validate that the diminished N100 effect ( to targets) is in direct consequence to the emotional information.