The Computational and Neural Mechanisms Linking Decision-making and Memory in Humans

Study Overview
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Brief Summary
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Learning to make good decisions in the present, and accurately recalling events and information from the past, are critical aspects of human cognition that are often impaired in many psychiatric disorders. This project aims to identify the how the choices individuals make influence what, and how, people remember by combining disparate techniques in computational modeling and direct brain recordings in human subjects. The researcher developed a dual-task paradigm, probing how decisions in one task affect immediate recognition memory. To examine the neural mechanisms underlying model-free RL's influence on memory, the researcher will record local field potential (LFP) and single neuron activity in various brain regions as epilepsy patients perform the proposed task. The results of this project will identify specific neurocomputational mechanisms unifying decision-making and memory processes.

Official Title
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The Computational and Neural Mechanisms Linking Decision-making and Memory in Humans

Conditions
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Memory, Short-Term

Intervention / Treatment
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* Behavioral: Value-manipulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Has seizure activity which is deemed non-responsive to standard pharmacological intervention(s), as determined by treating Neurologist and established clinical practices Has elected to receive clinically indicated intracranial EEG (electrocorticography (ECoG), stereoelectroencephalography (SEEG)) and/or temporal responsive neurostimulation (RNS) for medication-refractory epilepsy outside of this research study, as determined by treating clinician(s) and per current clinical practice Capacity to provide written informed consent Language proficiency in English or Spanish Willing and able to comply with all study-related procedures Exclusion Criteria: History of psychosis, such as in the context of depressive or manic episode. Active suicidal ideation with intent, suicide attempt within the last six months, or other serious suicide risk Inability to provide informed consent or reliably participate in study assessments, as per the Montreal Cognitive Assessment (MOCA; score < 26) or in the opinion of the evaluating neuropsychologist. Individuals unwilling or unable to undergo electrode implantation procedures Medical contraindications to neurosurgery or for general anesthesia, neurosurgery, or an MRI scan (required for electrode implantation) Neurological disorder other than epilepsy or other significant brain pathology, if contraindicated in the opinion of implanting neurosurgeon. Women who are pregnant

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Value-manipulation<br>Participants with epilepsy will complete a behavioral task in which they use a laptop computer to do a decision-making and memory task. | Behavioral: Value-manipulation<br>* During the decision-making task, different choices are assigned different values probabilistically.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Local-field potentials changes | Detection of local-field potentials (LFPs) in the various regions (hippocampus, amygdala, and frontal cortex). Local field potentials are the biological voltages recorded by macroelectrodes implanted in participant's subcortical regions as part of their treatment for epilepsy. LFP changes (measured as increases or decreases in voltage) as a function of participant behavior will be recorded, and in response to the task manipulation of the value of choices during the decision-making task | During task participation, approx. 30-45 min in the first 2 weeks of hospital stay | 
| Firing rate changes | Single-neuron activity recorded from the hippocampus, amygdala, and frontal cortex. Single-neuron activity refers the micro-scale changes in single-neuron action potentials recorded by microelectrodes implanted in subcortical regions. Firing rate changes (measured as difference in spikes/seconds [Hz]) will be reported for neurons as a function of how behavior changes when the value of choices is altered. | During task participation, approx. 30-45 min in the first 2 weeks of hospital stay | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reaction time | Reaction times involve measuring how quickly the participant makes each choice during the decision-making and memory tasks, in milliseconds. This will be recorded by logging keypresses and mouse inputs to the behavioral computers. Slow reaction times indicate increased cognitive processing. | During task participation, approx. 30-45 min in the first 2 weeks of hospital stay | 
| Number of hit rates for decision-making | Choices in decision-making task involved logging the decision-making selections that participants make. This will be recorded by logging keypresses and mouse inputs (left or right) to the behavioral computers. This will be used to track whether participants decisions change when value manipulations occur. | During task participation, approx. 30-45 min in the first 2 weeks of hospital stay | 
| Number of hit rates for Memory performance | Memory performance involved logging the memory-recognition selections that participants make. This will be recorded by logging keypresses and mouse inputs (old or new) to the behavioral computers. This will be used to track whether participants memory performance changes when value manipulations occur. | During task participation, approx. 30-45 min in the first 2 weeks of hospital stay |