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- Creators: School of Life Sciences
- Creators: Tsakalis, Konstantinos
Description
Development of post-traumatic epilepsy (PTE) after traumatic brain injury (TBI) is a major health concern (5% - 50% of TBI cases). A significant problem in TBI management is the inability to predict which patients will develop PTE. Such prediction, followed by timely treatment, could be highly beneficial to TBI patients. Six male Sprague-Dawley rats were subjected to a controlled cortical impact (CCI). A 6mm piston was pneumatically driven 3mm into the right parietal cortex with velocity of 5.5m/s. The rats were subsequently implanted with 6 intracranial electroencephalographic (EEG) electrodes. Long-term (14-week) continuous EEG recordings were conducted. Using linear (coherence) and non-linear (Lyapunov exponents) measures of EEG dynamics in conjunction with measures of network connectivity, we studied the evolution over time of the functional connectivity between brain sites in order to identify early precursors of development of epilepsy. Four of the six TBI rats developed PTE 6 to 10 weeks after the initial insult to the brain. Analysis of the continuous EEG from these rats showed a gradual increase of the connectivity between critical brain sites in terms of their EEG dynamics, starting at least 2 weeks prior to their first spontaneous seizure. In contrast, for the rats that did not develop epilepsy, connectivity levels did not change, or decreased during the whole course of the experiment across pairs of brain sites. Consistent behavior of functional connectivity changes between brain sites and the "focus" (site of impact) over time was demonstrated for coherence in three out of the four epileptic and in both non-epileptic rats, while for STLmax in all four epileptic and in both non-epileptic rats. This study provided us with the opportunity to quantitatively investigate several aspects of epileptogenesis following traumatic brain injury. Our results strongly support a network pathology that worsens with time. It is conceivable that the observed changes in spatiotemporal dynamics after an initial brain insult, and long before the development of epilepsy, could constitute a basis for predictors of epileptogenesis in TBI patients.
ContributorsTobin, Edward (Author) / Iasemidis, Leonidas (Thesis advisor) / Tsakalis, Konstantinos (Committee member) / Muthuswamy, Jitendran (Committee member) / Arizona State University (Publisher)
Created2012
Description
Approximately 1% of the world population suffers from epilepsy. Continuous long-term electroencephalographic (EEG) monitoring is the gold-standard for recording epileptic seizures and assisting in the diagnosis and treatment of patients with epilepsy. However, this process still requires that seizures are visually detected and marked by experienced and trained electroencephalographers. The motivation for the development of an automated seizure detection algorithm in this research was to assist physicians in such a laborious, time consuming and expensive task. Seizures in the EEG vary in duration (seconds to minutes), morphology and severity (clinical to subclinical, occurrence rate) within the same patient and across patients. The task of seizure detection is also made difficult due to the presence of movement and other recording artifacts. An early approach towards the development of automated seizure detection algorithms utilizing both EEG changes and clinical manifestations resulted to a sensitivity of 70-80% and 1 false detection per hour. Approaches based on artificial neural networks have improved the detection performance at the cost of algorithm's training. Measures of nonlinear dynamics, such as Lyapunov exponents, have been applied successfully to seizure prediction. Within the framework of this MS research, a seizure detection algorithm based on measures of linear and nonlinear dynamics, i.e., the adaptive short-term maximum Lyapunov exponent (ASTLmax) and the adaptive Teager energy (ATE) was developed and tested. The algorithm was tested on long-term (0.5-11.7 days) continuous EEG recordings from five patients (3 with intracranial and 2 with scalp EEG) and a total of 56 seizures, producing a mean sensitivity of 93% and mean specificity of 0.048 false positives per hour. The developed seizure detection algorithm is data-adaptive, training-free and patient-independent. It is expected that this algorithm will assist physicians in reducing the time spent on detecting seizures, lead to faster and more accurate diagnosis, better evaluation of treatment, and possibly to better treatments if it is incorporated on-line and real-time with advanced neuromodulation therapies for epilepsy.
ContributorsVenkataraman, Vinay (Author) / Jassemidis, Leonidas (Thesis advisor) / Spanias, Andreas (Thesis advisor) / Tsakalis, Konstantinos (Committee member) / Arizona State University (Publisher)
Created2012
Description
The research question this thesis aims to answer is whether depressive symptoms of adolescents involved in romantic relationships are related to their rejection sensitivity. It was hypothesized that adolescents who have more rejection sensitivity, indicated by a bigger P3b response, will have more depressive symptoms. This hypothesis was tested by having adolescent couples attend a lab session in which they played a Social Rejection Task while EEG data was being collected. Rejection sensitivity was measured using the activity of the P3b ERP at the Pz electrode. The P3b ERP was chosen to measure rejection sensitivity as it has been used before to measure rejection sensitivity in previous ostracism studies. Depressive symptoms were measured using the 20-item Center for Epidemiological Studies Depression Scale (CES-D, Radloff, 1977). After running a multiple regression analysis, the results did not support the hypothesis; instead, the results showed no relationship between rejection sensitivity and depressive symptoms. The results are also contrary to similar literature which typically shows that the higher the rejection sensitivity, the greater the depressive symptoms.
ContributorsBiera, Alex (Author) / Dishion, Tom (Thesis director) / Ha, Thao (Committee member) / Shore, Danielle (Committee member) / Barrett, The Honors College (Contributor)
Created2015-05
Description
Previous research has showed that auditory modulation may be affected by pure tone
stimuli played prior to the onset of speech production. In this experiment, we are examining the
specificity of the auditory stimulus by implementing congruent and incongruent speech sounds in
addition to non-speech sound. Electroencephalography (EEG) data was recorded for eleven adult
subjects in both speaking (speech planning) and silent reading (no speech planning) conditions.
Data analysis was accomplished manually as well as via generation of a MATLAB code to
combine data sets and calculate auditory modulation (suppression). Results of the P200
modulation showed that modulation was larger for incongruent stimuli than congruent stimuli.
However, this was not the case for the N100 modulation. The data for pure tone could not be
analyzed because the intensity of this stimulus was substantially lower than that of the speech
stimuli. Overall, the results indicated that the P200 component plays a significant role in
processing stimuli and determining the relevance of stimuli; this result is consistent with role of
P200 component in high-level analysis of speech and perceptual processing. This experiment is
ongoing, and we hope to obtain data from more subjects to support the current findings.
stimuli played prior to the onset of speech production. In this experiment, we are examining the
specificity of the auditory stimulus by implementing congruent and incongruent speech sounds in
addition to non-speech sound. Electroencephalography (EEG) data was recorded for eleven adult
subjects in both speaking (speech planning) and silent reading (no speech planning) conditions.
Data analysis was accomplished manually as well as via generation of a MATLAB code to
combine data sets and calculate auditory modulation (suppression). Results of the P200
modulation showed that modulation was larger for incongruent stimuli than congruent stimuli.
However, this was not the case for the N100 modulation. The data for pure tone could not be
analyzed because the intensity of this stimulus was substantially lower than that of the speech
stimuli. Overall, the results indicated that the P200 component plays a significant role in
processing stimuli and determining the relevance of stimuli; this result is consistent with role of
P200 component in high-level analysis of speech and perceptual processing. This experiment is
ongoing, and we hope to obtain data from more subjects to support the current findings.
ContributorsTaylor, Megan Kathleen (Author) / Daliri, Ayoub (Thesis director) / Liss, Julie (Committee member) / School of Life Sciences (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Previous research demonstrated the overall efficacy of an embodied language intervention (EMBRACE) that taught pre-school children how to simulate (imagine) language in a heard narrative. However, EMBRACE was not effective for every child. To try to explain this variable response to the intervention, the video recordings made during the four-day intervention sessions were assessed and emotion was coded. Each session was emotion-coded for child emotions and for child-researcher emotions. The child specific emotions were 1) engagement in the task, this included level of participation in the activity, 2) motivation/attention to persist and complete the task, as well as stay focused, and 3) positive affect throughout the session. The child-researcher specific emotions were 1) engagement with each other, this involved how the child interacted with the researcher and under what context, and 2) researcher’s positive affect, this incorporated how enthusiastic and encouraging the researcher was throughout the session. It was hypothesized that effectiveness of the intervention would be directly correlated with the degree that the child displayed positive emotions during the intervention. Thus, the analysis of these emotions should highlight differences between the control and EMBRACE group and help to explain variability in effectiveness of the intervention. The results did indicate that children in the EMBRACE group generally had a significantly higher positive affect compared to the control group, but these results did not influence the ability for the child to effectively recall or moderate the EEG variables in the post-test. The results also showed that children who interacted with the researcher more tended to be in the EMBRACE group, whereas children who did not interact with the researcher more frequently were in the control group, showing that the EMBRACE intervention ended up being a more collaborative task.
ContributorsOtt, Lauren Ruth (Author) / Glenberg, Arthur (Thesis director) / Presson, Clark (Committee member) / Kupfer, Anne (Committee member) / School of Life Sciences (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
In the study of the human brain’s ability to multitask, there are two perspectives: concurrent multitasking (performing multiple tasks simultaneously) and sequential multitasking (switching between tasks). The goal of this study is to investigate the human brain’s ability to “multitask” with multiple demanding stimuli of approximately equal concentration, from an electrophysiological perspective different than that of stimuli which don’t require full attention or exhibit impulsive multitasking responses. This study investigates the P3 component which has been experimentally proven to be associated with mental workload through information processing and cognitive function in visual and auditory tasks, where in the multitasking domain the greater attention elicited, the larger P3 waves are produced. This experiment compares the amplitude of the P3 component of individual stimulus presentation to that of multitasking trials, taking note of the brain workload. This study questions if the average wave amplitude in a multitasking ERP experiment will be the same as the grand average when performing the two tasks individually with respect to the P3 component. The hypothesis is that the P3 amplitude will be smaller in the multitasking trial than in the individual stimulus presentation, indicating that the brain is not actually concentrating on both tasks at once (sequential multitasking instead of concurrent) and that the brain is not focusing on each stimulus to the same degree when it was presented individually. Twenty undergraduate students at Barrett, the Honors College at Arizona State University (10 males and 10 females, with a mean age of 18.75 years, SD= 1.517) right handed, with normal or corrected visual acuity, English as first language, and no evidence of neurological compromise participated in the study. The experiment results revealed that one- hundred percent of participants undergo sequential multitasking in the presence of two demanding stimuli in the electrophysiological data, behavioral data, and subjective data. In this particular study, these findings indicate that the presence of additional demanding stimuli causes the workload of the brain to decrease as attention deviates in a bottleneck process to the multiple requisitions for focus, indicated by a reduced P3 voltage amplitude with the multitasking stimuli when compared to the independent. This study illustrates the feasible replication of P3 cognitive workload results for demanding stimuli, not only impulsive-response experiments, to suggest the brain’s tendency to undergo sequential multitasking when faced with multiple demanding stimuli. In brief, this study demonstrates that when higher cognitive processing is required to interpret and respond to the stimuli, the human brain results to sequential multitasking (task- switching, not concurrent multitasking) in the face of more challenging problems with each stimulus requiring a higher level of focus, workload, and attention.
ContributorsNeill, Ryan (Author) / Brewer, Gene (Thesis director) / Peter, Beate (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Transcranial Current Stimulation (TCS) is a long-established method of modulating neuronal activity in the brain. One type of this stimulation, transcranial alternating current stimulation (tACS), is able to entrain endogenous oscillations and result in behavioral change. In the present study, we used five stimulation conditions: tACS at three different frequencies (6Hz, 12Hz, and 22Hz), transcranial random noise stimulation (tRNS), and a no-stimulation sham condition. In all stimulation conditions, we recorded electroencephalographic data to investigate the link between different frequencies of tACS and their effects on brain oscillations. We recruited 12 healthy participants. Each participant completed 30 trials of the stimulation conditions. In a given trial, we recorded brain activity for 10 seconds, stimulated for 12 seconds, and recorded an additional 10 seconds of brain activity. The difference between the average oscillation power before and after a stimulation condition indicated change in oscillation amplitude due to the stimulation. Our results showed the stimulation conditions entrained brain activity of a sub-group of participants.
ContributorsChernicky, Jacob Garrett (Author) / Daliri, Ayoub (Thesis director) / Liss, Julie (Committee member) / School of Life Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05