Author ORCID Identifier

0000-0003-4319-9200

Date of Graduation

12-2022

Document Type

Dissertation (PhD)

Program Affiliation

Neuroscience

Degree Name

Doctor of Philosophy (PhD)

Advisor/Committee Chair

Francesco Versace

Committee Member

Scott Lane

Committee Member

Qingchun Tong

Committee Member

Marina Vannucci

Committee Member

Shelli Kesler

Abstract

Due to individual differences in the brain’s reward system, some individuals are more vulnerable than others to maladaptive, reward-seeking behaviors, such as substance use or compulsive eating. A body of research has demonstrated that individuals who attribute higher levels of incentive salience to reward-associated cues than to pleasant images (termed “C>P group” throughout) are more vulnerable to compulsive eating than those who attribute higher incentive salience to pleasant images than reward- associated cues (P>C group). Meanwhile, a separate body of research has demonstrated that cognitive control also regulates eating by enabling top-down attentional control. This dissertation aims to identify how both cognitive control and incentive salience act in tandem to regulate cue-induced eating. A central question of this research is: do individuals in the C>P group also show attenuated cognitive control?

Because the animal literature indicates that individuals who attribute high incentive salience to reward-associated cues also show attenuated top-down attentional control, I hypothesized that C>P individuals would also show attenuated cognitive control relative to P>C individuals. To test this hypothesis, I analyzed electroencephalogram (EEG) data collected during a controlled cued food delivery task, in which participants viewed images and were dispensed food rewards (candy) that they could choose to eat or discard, and non-food objects (beads, control condition). From the EEG recordings, I calculated the amplitude of the late positive potential (LPP) and power (µV2) in the theta (θ, 4-8 Hz) frequency band as metrics of affective and cognitive processing, respectively. To identify individual differences in both affective and cognitive processing, I then conducted two separate K-means (k = 2) cluster analyses using LPP and theta power data.

The LPP-based cluster analysis replicated previous findings: C>P individuals ate significantly more candies during the experiment than P>C individuals. However, I found no significant differences in theta power between the P>C and C>P groups. Meanwhile, the theta-based cluster analysis found that some individuals show higher theta during the candy condition than the bead condition (θCA>θBE), while others show higher theta power during the bead condition than the candy condition (θBE>θCA). Furthermore, the θCA>θBE group ate significantly more during the experiment than the θBE>θCA group. Finally, I crossed group assignments from both the LPP- and theta-based cluster analyses to create four groups based on LPP- and theta-based risk factors: those with no risk factors (P>C & θBE>θCA group), those with only an LPP risk factor (C>P & θCA>θBE), those with only a theta risk factor (P>C & θCA>θBE), and finally those with both risk factors (C>P & θCA>θBE). I found that individuals with no risk factors ate the least of all four groups, and the other three groups showed significantly higher levels of eating behavior on average.

From these results, I can conclude that both cognitive and affective brain systems are involved in regulating cue-induced eating. However, the finding that P>C and C>P individuals do not show significant differences in theta power suggests that cognitive and affective mechanisms may act independently in humans. Because an individual with an affective vulnerability to cue-induced eating may not also have a cognitive vulnerability, this underscores the need for targeted, individualized treatments for maladaptive behaviors. For example, these research findings could be applied to the use of transcranial magnetic stimulation (TMS) to ameliorate addictive disorders: individuals with higher theta power during food-related decision-making may be selected for excitatory stimulation of brain regions associated with cognitive control, such as dorsolateral prefrontal cortex (dlPFC), whereas individuals who attribute high incentive salience to reward-related cues may benefit from inhibitory stimulation of reward-associated areas, such as medial prefrontal cortex (mPFC).

Keywords

cognitive control, incentive salience, cue-induced behavior, psychophysiology, ERPs, LPP, theta, EEG, eating behavior, cue-induced behavior

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