Abstract

Moderate-to-severe traumatic brain injury (M/S TBI) can affect an individual's ability to perform daily tasks. For example, individuals with M/S TBI are more likely to commit errors on tasks such as making a meal or wrapping a present. The neural processes involved in such errors are poorly understood. Studies suggest that neurophysiologic markers of cognitive control and error processing may be helpful in gaining additional insight into errors on naturalistic action tasks. Unfortunately, previous experimental methods left a methodological gap which limited the use of neurophysiological markers in the study of naturalistic action. Several recent studies in healthy adults have suggested one method of bridging the gap by having individuals observe another person's errors. The current study was the first study to employ the method in a TBI population as a possible means of gaining additional insight into the detrimental effects of M/S TBI on the performance of naturalistic actions. In order to gain additional insight into the effects of M/S TBI on the completion of naturalistic tasks I used two neurophysiologic markers of cognitive control and error processing. They were the observer error related negativity (oERN) and the P300 components of the scalp-recorded event-related potential (ERP). I hypothesized that individuals with M/S TBI would demonstrate error-specific changes in the two oERN and P300 that would correlate with self-reported difficulties in daily functioning. The study consisted of two experiments. One compared 15 individuals with M/S TBI to 17 demographically similar healthy controls on an error related naturalistic action based picture task. The second compared an overlapping sample of 16 individuals with M/S TBI to 16 demographically similar controls as they watched a confederate complete the Erikson flanker task, a commonly used task in the study of electrophysiological markers. Accuracy (error vs. correct) and group (M/S TBI vs. control) effects were analyzed using 2 x 2 repeated measures ANOVAs on ERP amplitude and latency. Pearson product-moment correlations were calculated to evaluate the relationship between the P300 and oERN and measures of self-reported executive functioning (Frontal Systems Behavior Scale, FrSBe) and neuropsychological measures. Findings supported a difference between the control and M/S TBI groups in how errors were processed during the naturalistic actions based picture task. There was an interaction between group membership and response accuracy (error vs. correct) on P300 amplitude and P300 latency. Controls demonstrated reduced P300 amplitude and latency on error trials compared to correct trials. Individuals with M/S TBI did not demonstrate a significant difference between correct trials and error trials on P300 amplitude and latency. The amplitude and latency of the P300 were correlated with self-reported functional difficulties in individuals with M/S TBI but not control participants. A Fisher's r -- z analysis indicated that correlations differed significantly between groups; however, an outlier was identified in the correlational data. Removal of the outlier data led to non-significant results in the Fisher's r -- z analysis. Taken together, results of the picture task supplied evidence that for individuals with M/S TBI differences in neurophysiologic markers between groups could be explained by reduced adaptation to complexity or by possible deficits in a secondary error processing pathway for complex errors. Future research could focus on better defining the functional relationship between P300 amplitude and latency and increased errors in naturalistic actions following M/S TBI. Observation of the flanker task did not elicit oERN waveforms from either healthy controls or from individuals with M/S TBI. The results could be due to problems with the current task, but also raised some concerns about previous studies using the flanker task which employed a slightly different methodology requiring participants to count errors. The current study did not require participant to count errors. As a whole, the study supplied partial support for using electrophysiological markers of error processing to gain additional understanding increased errors in the performance of naturalistic actions following M/S TBI.

Degree

PhD

College and Department

Family, Home, and Social Sciences; Psychology

Rights

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