Decoding and Selective Modulation of Human Memory During Awake/Sleep Cycles

University of California, Los Angeles150 enrolled

Overview

The proposed project seeks to elucidate memory processes and consolidation during sleep by leveraging the unique capability of direct recordings from the human brain at multiple levels of resolution-single neurons, localized neuronal assemblies, intracranial local field potentials-during rich behavioral tasks with real-life narratives and extracting neural features that relate to different aspects of episodic experience. The investigators will further probe causal mechanisms of consolidation by application of auditory and electrical stimulations during sleep and its effect on modulating memory processes.

Study Type

INTERVENTIONAL

Allocation

Purpose

BASIC_SCIENCE

Masking

SINGLE

Enrollment

150

Conditions

Memory, Delayed

Interventions

Auditory and Electrical Stimulation

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria: * All epilepsy patients between the ages of 18 and 65 who undergo depth electrode placement for clinical purposes * Eligibility is determined by the epilepsy surgery team (based on neuropsychological testing and on psychiatric evaluation) * Willing to provide informed consent and participate the study Exclusion Criteria: * Neurological or psychiatric issues, other than epilepsy, that would put the patient at risk * Patient is younger than 18 or older than 65 years of age * Unwilling to provide informed consent

Outcomes

Primary Outcomes

Recognition Accuracy

Accuracy will be analyzed to evaluate performance on memory tasks before and after sleep, specifically the ability to recognize correct items compared to all items. Accuracy will be measured using the sum of true positive and true negative divided by the total number of items. A within-subjects design will be employed and accuracy for stimulated vs. non-stimulated items will be compared.

Time frame: 1-2 days contained within the participants' 1-2 week hospital stay; Specifically for each experiment, the outcome measure will be computed during the pre- and post-sleep memory tasks

Recognition Discriminability (D-prime)

Discriminability will be analyzed to evaluate performance on memory tasks before and after sleep, specifically the ability to recognize target items from distractor items. Discriminability will be measured using a discriminability index (d-prime). In addition to d-prime being a normalized metric, it provides critical and complementary information to the accuracy metric (Outcome 1) given that it is a measure of sensitivity (and not bias) in the cases where data labels are not balanced . A within-subjects design will be employed and discriminability for stimulated vs. non-stimulated items will be compared.

Time frame: 1-2 days contained within the participants' 1-2 week hospital stay; Specifically for each experiment, the outcome measure will be computed during the pre- and post-sleep memory tasks.

Secondary Outcomes

Power sleep oscillations

The power of slow waves, spindles, ripples (all in units of dbm) will be computed. Employing a within-subjects design, the investigators will compare the change in the power of these oscillatory features for stimulated vs. non-stimulated items.

Time frame: 1-2 days contained within the participants' 1-2 week hospital stay. Specifically for each experiment, the outcome measure will be computed during the sleep period between pre and post-sleep memory tasks.

Neuronal replay index

Neuronal replay index, defined as the percentage of time during which neurons manifest replay-like activation as compared to the duration of deep sleep will be computed. Employing a within-subjects design, the investigators will compare the replay measure for stimulated vs. non-stimulated items.