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.

Purpose: The purpose of this study was to examine the effects of long-term (24 weeks) physical activity on attention allocated toward food in college freshmen women. Methods: Seventy-nine freshmen college women wore a multi-function pedometer for 24 weeks after being randomly assigned to a daily step level: 10,000; 12,500; or 15,000. After at least 16 weeks of intervention, participants were given a cognitive viewing task (pictures of food and flowers) with the neural response measured using electroencephalogram (EEG) and event-related potentials (ERPs). P300s and LPPs are components of the ERP indicating increased attention to stimuli. Results: There was a significant difference in daily step counts between groups. No interaction between step group and picture condition (food vs. flowers) was found for any of the three ERP (event-related potential) variables (P300 amplitude, P300 latency, LPP amplitude). The 12,500 group showed a significantly elevated response in comparison to the other groups for both food and flowers (F=8.84; P=0.0002). Additionally, subjective rating of hunger was significantly lower in the 15,000 step group (F=4.72; P=0.0030). Conclusion: It appears that long-term increases in physical activity are capable of reducing neural orientation toward hedonic food cues as well as subjective hunger ratings. In addition to increasing energy expenditure, increases in long-term physical activity may also influence the physiological drive to consume food.

Cross modality matching is a magnitude matching procedure, developed to study the relationships between sensory modalities. Auditory and visual sensory integration can be examined through cross modality matching of brightness and loudness. Brightness and loudness are natural correlates of one another as they both represent the parameter of intensity for their respective sensory modalities. Past studies have demonstrated that typical individuals tend to match brighter lights with louder sounds and dimmer lights with softer sounds. The current study utilized a modified cross modality matching procedure, combined with electroencephalography (EEG) data, to examine the cortical response to sensory integration. It was hypothesized that the response latency and cortical distribution of the EEG data would show differences between matched and unmatched conditions of light and sound stimuli. Light and sound stimuli were presented to 10 participants (five males and five females between the ages of 18 and 28 years) in a forced choice paradigm. The behavioral responses, reaction times, and EEG data were recorded for each patient. Results demonstrated that there were significant differences in behavioral reaction time among the stimulus conditions. However, reaction times were only significantly faster for the loudest sound paired with the brightest light. No other pairs of matched stimuli resulted in faster reaction times. Event related potentials (ERPs) were identified for matched and unmatched stimulus conditions. No differences were identified in latency of the ERPs among conditions. Additionally, source localization revealed that dipole locations for each stimulus condition remained relatively constant in the prefrontal cortex. As the prefrontal cortex has been found to be associated with decision-making and sensory integration, it can be concluded that sensory integration did occur. However, the processing of sensory information did not change for matched or unmatched conditions of light and sound.

The present study investigated how heightened P3a effects may be induced using a free-operant paradigm rather than traditional two and three stimulus oddballs. This was accomplished by using a fixed set of stimuli and mixed FR5 and VR5 reinforcement schedules. Most participants showed heightened P3a effects in the VR5 conditions, but a few participants did not. The data for the group that did not show the P3a effect in their data were variable, and definite conclusions about the factors related to the non-occurrence of the P3a were not researched. Despite this, there appears to be a relation between operant behavior dimensions (i.e., reaction time and response rate) and the P3a effect, with higher reaction times and lower response rates correlated to more significant P3a effects. Limitations discussed include the use of too simple of a behavioral topography and the lack of anecdotal participant interviews that could shed light on deviant performances.

The auditory system is able to recognize auditory objects and is thought to form predictive models of them even though the acoustic information arriving at our ears is often imperfect, intermixed, or distorted. We investigated implicit regularity extraction for acoustically intact versus disrupted six-tone sound patterns via event-related potentials (ERPs). In an exact-repetition condition, identical patterns were repeated; in two distorted-repetition conditions, one randomly chosen segment in each sound pattern was replaced either by white noise or by a wrong pitch. In a roving-standard paradigm, sound patterns were repeated 1–12 times (standards) in a row before a new pattern (deviant) occurred. The participants were not informed about the roving rule and had to detect rarely occurring loudness changes. Behavioral detectability of pattern changes was assessed in a subsequent behavioral task. Pattern changes (standard vs. deviant) elicited mismatch negativity (MMN) and P3a, and were behaviorally detected above the chance level in all conditions, suggesting that the auditory system extracts regularities despite distortions in the acoustic input. However, MMN and P3a amplitude were decreased by distortions. At the level of MMN, both types of distortions caused similar impairments, suggesting that auditory regularity extraction is largely determined by the stimulus statistics of matching information. At the level of P3a, wrong-pitch distortions caused larger decreases than white-noise distortions. Wrong-pitch distortions likely prevented the engagement of restoration mechanisms and the segregation of disrupted from true pattern segments, causing stronger informational interference with the relevant pattern information

No description available.

No description available.

<p>Neural responses to anticipatory coarticulatory cues were investigated across systematically varying phonological conditions. Congruent or incongruent subphonemic information was placed between an initial consonant and a vowel in a consonant-vowel- consonant (CVC) spoken word (Archibald & Joanisse, 2011). Due to physical and temporal differences across sound classes, the objective was to investigate whether coarticulatory information would be processed differently across controlled manipulations of onset (fricative vs. stop) and vowel type (height vs. backness). Event- related potentials (ERPs) were recorded during a printed-word/spoken-word matching paradigm, in which participants indicated whether a visual prime stimulus and a spoken word matched/mismatched. The “Phonological Mapping Negativity” (PMN) component provides strong evidence that the use of coarticulatory information in speech recognition varies in strength and timing as a function of onset type (fricative vs. stop) and vowel height (high vs. low). Coarticulatory cues were more readily perceived in spoken word beginning with fricatives than with stops. Similarly, subphonemic variations were more easily detected in low vowels than in high vowels. Observed perceptual and temporal differences are interpreted to reflect variations in subphonemic and phonological processing.</p> / Master of Science (MSc)

When presented with two identical sounds from different locations separated by a short onset asynchrony, listeners report hearing a single source at the location of the lead sound, a phenomenon called the precedence effect (Wallach et al., 1949; Haas, 1951). When the onset asynchrony is above echo threshold, listeners report hearing the lead and lag sounds as separate sources with distinct locations. Event-related potential (ERP) studies have shown that perception of separate sound sources is accompanied by an object-related negativity (ORN) 100-250 ms after onset and a late posterior positivity (LP) 300-500 ms after onset (Sanders et al., 2008; Sanders et al., 2011). The current study tested whether these ERP effects are modulated by attention. Clicks were presented in lead/lag pairs at and around listeners’ echo thresholds while in separate blocks they 1) attended to the sounds and reported if they heard the lag sound as a separate source, and 2) performed a difficult 2-back visual task. Replicating previous results, when attention was directed to the sounds, an ORN and LP were observed for click pairs 1 ms above compared to 1 ms below echo threshold. In contrast, when attention was directed away from the sounds to the visual task, neither the ORN nor the LP was evident. Instead, click pairs 1 ms above echo threshold elicited an anterior positivity 250-450 ms after onset. In addition, an effect resembling an ORN was found in comparing ERPs elicited by unattended click pairs with SOAs below attended echo threshold. These results indicate that attention modulates early perceptual processes in the precedence effect and may be critical for auditory object formation under these conditions.

No description available.