Cognitive Demands and Electrical Stimulation in Memory Function Research

Recruiting in Palo Alto (17 mi)

+1 other location

Overseen ByJoel Voss, PhD

Age: 18 - 65

Sex: Any

Travel: May be covered

Time Reimbursement: Varies

Trial Phase: Academic

Waitlist Available

Sponsor: University of Chicago

No Placebo Group

Trial Summary

What is the purpose of this trial?This project tests the role of the human hippocampus in providing online representation of episodic content and providing the top-down signals to brain networks for visuospatial attention and visual processing needed to drive visual sampling for the formation of coherent episodic memories. This hypothesis will be tested in several experiments that measure and manipulate hippocampal activity within eye-tracking tasks designed to isolate the interplay between memory and visual sampling during memory formation. These experiments will be performed in individuals with epilepsy undergoing neurosurgical procedures as part of clinical care, as this provides invasive recordings of neural activity (intracranial electroencephalography, or "iEEG") from the hippocampus and other regions of interest with temporal resolution that matches the rapid pace of eye movements. The temporal resolution of iEEG is key to addressing the hypotheses concerning how the hippocampus drives visual sampling, in addition to responding to it. Direct electrical stimulation through the iEEG electrodes will also be used to test the necessary role of hippocampal processing in driving active visual sampling. By rigorously testing the role of hippocampus in interaction with large-scale networks during the process of memory formation that occurs via active sampling, this project aims to better understand mechanisms relevant to the disruptions of memory formation that occur in neurological and psychiatric disorders.

Eligibility Criteria

This study is for adults over 18 with normal or corrected vision who speak English natively. It's designed for individuals with epilepsy undergoing neurosurgical procedures, allowing researchers to record and stimulate brain activity directly.

Participant Groups

The trial investigates how the hippocampus influences memory formation and visual processing. Participants will perform eye-tracking tasks while receiving different cognitive challenges and electrical stimulations to their brains.

6Treatment groups

Experimental Treatment

Group I: Experiment 6Experimental Treatment1 Intervention

The same group of 20 iEEG subjects that are included in Study Experiment Condition 5 will perform the same eye-tracking memory task as described for Study Experiment Condition 2. This experiment condition will be performed on a different day of the inpatient visit than participation in Study Experiment Condition 5.

Group II: Experiment 5Experimental Treatment1 Intervention

Subjects with iEEG electrodes implanted will perform the same eye-tracking memory task as described for Study Experiment Condition 1. This is a different group of iEEG subjects selected based on having iEEG electrodes implanted in the hippocampus as well as in at least one location of the Dorsal Attention Network (DAN), which is a region of interest for the experiment condition. 20 subjects undergoing iEEG recordings as part of epilepsy treatment will be assigned to this study experiment condition.

Group III: Experiment 4Experimental Treatment2 Interventions

The same 20 subjects with iEEG electrodes implanted who perform Study Experiment Condition 1 will perform the same eye-tracking memory task described for Study Experiment Condition 2. For these subjects, high-frequency electrical stimulation will be delivered through the iEEG electrodes on a subset of study trials, with half of stimulated trials receiving stimulation of the hippocampus and the other half receiving stimulation of the amygdala. This memory task will take about 1.5 hours to complete and will be performed on a different day of their inpatient visit than the procedures for Study Experiment Condition 1.

Group IV: Experiment 3Experimental Treatment2 Interventions

The same 20 subjects with iEEG electrodes implanted who perform Study Experiment Condition 2 will perform the same eye-tracking memory task described for Study Experiment Condition 1. For these subjects, high-frequency electrical stimulation will be delivered through the iEEG electrodes on a subset of study trials, with half of stimulated trials receiving stimulation of the hippocampus and the other half receiving stimulation of the amygdala. This memory task will take about 1.5 hours to complete and will be performed on a different day of their inpatient visit than the procedures for Study Experiment Condition 2.

Group V: Experiment 2Experimental Treatment1 Intervention

Subjects with iEEG electrodes implanted will perform an eye-tracking memory task in which they view arrays of everyday objects arranged as a grid and later undergo memory testing for these object image arrays. Half of the object-image arrays are studied actively (subjects view objects in any order they wish) and half are studied passively (viewing patterns are predetermined and subjects must follow along). For the memory test, subjects attempt to pick studied objects from among novel (foil) objects and replace them at studied locations using the computer mouse. Eye movements will be remotely (noninvasively) tracked using a camera during the study phases. This memory task will take about 1.5 hours to complete. 20 subjects undergoing iEEG recordings as part of epilepsy treatment will be assigned to this study experiment condition.

Group VI: Experiment 1Experimental Treatment1 Intervention

Subjects with iEEG electrodes implanted will perform an eye-tracking memory task in which they view pictures of naturalistic scenes and later undergo memory testing for these scene pictures. For the memory test, studied scenes will be repeated and presented along with novel (foil) scenes. Subjects will attempt to discriminate studied from novel scenes using button press responses. Eye movements will be remotely (noninvasively) tracked using a camera during both study and test. This memory task will take about 1.5 hours to complete. 20 subjects undergoing iEEG recordings as part of epilepsy treatment will be assigned to this study experiment condition.