Investigation of Oscillations Underlying Human Cognitive and Affective Processing Using Intracranial EEG

Study Overview
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Brief Summary
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Purpose: To investigate the electrophysiological correlates of human cognition and affective processing. Participants: Drug-resistant epilepsy patients undergoing epilepsy surgery cortical mapping with continuous electrocorticography (ECoG) with intracranial electrodes. Procedures (methods): Participants will perform computer-based cognitive and affective processing tasks during routine long-term monitoring. Intracranial EEG will be collected during the task

Detailed Description
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Oscillations in different frequency bands like theta, alpha, beta, gamma and high gamma are thought to underlie processing of cognitive and emotional information. For example, theta (3 - 7 Hz) and alpha (8 - 12 Hz) oscillations are known to underlie working memory as well as attentional processing. Theta oscillations are known to differentiate emotional and neutral stimuli while gamma oscillations (30 - 50 Hz) are known to underlie rapid integration of information. The fact that these oscillations are also disrupted in neuropsychiatric disorders underline the importance of these oscillations. A lot of our understanding of these oscillations come from non invasive methods in humans like electroencephalography (EEG), magnetoencephalography (MEG) and invasive methods in animal models. However, EEG and MEG measure oscillations that are generated by collective firing of large cortical patches thereby losing spatial resolution. Also activity from deeper structures like amygdala and hippocampus cannot be picked up in these modalities. Animal models often suffer from the poor translation of behavior from animals to humans and vice versa. Intracranial EEG or Electrocorticography (ECoG) helps overcome the drawbacks described above. Studies using ECoG have become widespread and have been helpful in elucidating the functional roles of different brain regions in cognition and emotion. The investigators aim to utilize these established procedures to study the role of oscillations recorded from different brain regions in cognition and emotion. Patients with medically refractory epilepsy undergo long-term invasive monitoring for surgical resection planning. Electrodes are implanted subdurally over seizure focus to identify seizure onset zone and patients are often in the epilepsy monitoring unit at the Neuroscience hospital for approximately a week. During this period, intracranial EEG is constantly acquired for clinical investigation. The investigators plan to recruit these patients while they undergo long-term monitoring to leverage the rare access to direct brain recordings and study the role of oscillations in cognitive and affective processing. Patients who provide informed consent to participate in the study will perform computer based cognitive and emotional processing tasks.

Official Title
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Investigation of Oscillations Underlying Human Cognitive and Affective Processing Using Intracranial EEG

Conditions
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Working Memory, Emotions

Intervention / Treatment
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* Behavioral: Working Memory Task
* Behavioral: Reward Learning Task
* Behavioral: Facial Emotion Recognition Task


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: History of medically intractable epilepsy Capable of giving informed consent Aged 18 - 80 years, either sex Exclusion Criteria: Major systemic illness Severe cognitive impairment defined as mini-mental state examination of less than 20 Severe psychiatric illness Excessive use of alcohol or other substances

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cognitive and Emotion Processing Tasks<br>As a part of the clinical monitoring, intracranial EEG is continuously collected when the participant is at the Epilepsy Monitoring Unit at the UNC Neuroscience Hospital. We will use an FDA approved EEG amplifier/data acquisition system to collect the research data. Computer-based tasks will be presented through a laptop and task related timing information will be transmitted from the laptop to the data acquisition system. Computer-based tasks will include Working Memory task, Reward Learning Task and Facial Emotion Recognition Task | Behavioral: Working Memory Task<br>* Sternberg Task Items, which can be visually presented alphabets, shapes or numbers or sound tones presented through speakers, will be presented to the participant. The participant will need to maintain the presented items in their memory and indicate, when a single probe item is presented, whether the probe item was present in the immediately preceding list by pressing a key on the keyboard. N-Back Task Items are presented continuously sequentially and participants are instructed to indicate whether items are repeated n items before by pressing a key on the keyboard. The task is divided into blocks of 0,1,2,3 -back trials based on the 'n'. For example in the 2 - back task, the participant has to indicate if the item presented 2 items before matches the current item. Similar to the previous task, the items can be presented visually or auditorily.<br>* Other names: N-Back Task;Behavioral: Reward Learning Task<br>* Two abstract visual stimuli are presented on the screen and participant is asked to choose one. Unknown to the participant, each stimulus is associated with distinct probabilities of virtual reward such that one stimulus is associated with net gain while the other is associated with net loss. The participant's goal is to maximize the reward. Once the participant identifies the stimulus associated with net gain, the reward probabilities are reversed. This process is repeated 5 times.<br>* Other names: Learning reversal task;Behavioral: Facial Emotion Recognition Task<br>* On a given trial, participants will be presented with images of two faces side-by-side. The faces will either match in terms of emotion category (e.g., 2 anger faces) or not (e.g., an anger face and a fear face). Faces presented together will always be of the same gender but different identities. Participants will be asked to determine whether the two faces presented depict the same emotion category.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intracranial EEG Spectra Power | Spectral analysis of electrophysiology data will be performed using multi-taper fft and wavelet transforms. The measures will be compared between different epochs within the tasks to determine what oscillations are modulated by the task. The correlation between the measures described above and the task performance will also be estimated. | Intracranial EEG will be collected simultaneously when the participants perform the task. 1 Hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Task Performance: Reaction Times | For all the tasks described above, the time from when the response is prompted and when the response is obtained is collected as reaction time. Reaction time is measured in milliseconds. | 1 Hour | 
| Intracranial EEG Functional Connectivity Analysis | Functional connectivity between the different electrodes will be measured using phase locking value and Granger causality. | Intracranial EEG will be collected simultaneously when the participants perform the task. 1 Hour |