Biology subjects

Hoefle, S.

Publications and source records attributed to Hoefle, S..

2 recordsLinked to original sources

bioRxiv2022

Transcranial electrical stimulation modulates emotional experience and metabolites in the prefrontal cortex in a donation task

In this study we investigated whether transcranial Direct Current Stimulation (tDCS) applied to two prefrontal cortex regions, the ventromedial prefrontal cortex (vmPFC, anode) and right dorsolateral prefrontal cortex (DLPFC, cathode) can be used to induce changes in self-reported emotions and modulate metabolite concentrations under both electrodes. We employed in vivo quantitative MR Spectroscopy (MRS) in healthy adult participants and quantified the changes in GABA and Glx complex (Glutamate and Glutamine) before and after five sessions of tDCS stimulation. tDCS was delivered at 2mA intensity for 20 minutes for the active group and 1 minute for the sham group. tDCS was applied over five days while participants were engaged in a charitable donation task, known to engage the reward network. We observed increased levels of GABA in vmPFC, but not in DLPFC. Glx levels were decreased in both vmPFC and DLPFC. We found that self-reported happiness increased significantly over time only in the active group. There was a decrease in self-reported guiltiness in both active and sham groups. Altogether, the results indicate that self-reported emotions can be modulated by prefrontal stimulation. This may be because the changes in GABA and Glx concentrations following repeated stimulation induce remote changes in the reward network through interactions with other metabolites, previously thought to be unreachable with noninvasive stimulation techniques.

neuroscience↗

bioRxiv2019

Development of Pavlovian-to-instrumental transfer (PIT) task to examine the effects of reward-predicting cues on behavioral activation in young adults

There is a growing recognition that much of human behavior is governed by the presence of classically conditioned cues. The Pavlovian-to-Instrumental Transfer (PIT) paradigm offers a way to measure the effects of classically conditioned stimuli on behavior. In the current study, a novel PIT paradigm was developed for use in conjunction with an fMRI classical conditioning task. This could allow for a measurement of BOLD responses to anticipated rewards, unconfounded by operant responses, while providing a behavioral measure of conditioning effects. Twenty-four healthy young adults completed 1) instrumental training, 2) Pavlovian conditioning, and 3) Transfer test. During instrumental training, participants learned to apply force on a handgrip to win money from slot machines pictured on a computer screen. During Pavlovian conditioning, slot machines appeared with one of two abstract symbols (cues), one symbol was predictive of monetary reward. During the Transfer test, participants again applied force on a handgrip to win more money. This time, slot machines were presented with the Pavlovian cues, but with the outcomes hidden. The results indicated increased effort on the instrumental task, i.e., higher response frequency and greater force, in the presence of a reward-predicting cue. Our findings add to a growing number of studies demonstrating PIT effects in humans. This paradigm was proved to be useful in measuring the effects of a conditioned stimulus on behavioral activation.

neuroscience↗