Journal
JOURNAL OF NEUROSCIENCE
Volume 40, Issue 37, Pages 7155-7168Publisher
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.0486-20.2020
Keywords
hippocampus; memory; noninvasive stimulation; recollection; simultaneous TMS/IMRI; theta-burst
Categories
Funding
- National Institute of Mental Health [R01-MH106512, R01-MH111790]
- National Institute of Neurological Disorders and Stroke [T32-NS047987, F31-NS111892]
- Office of the Provost
- Office for Research
- Northwestern University Information Technology
- Northwestern University Department of Radiology
Ask authors/readers for more resources
The hippocampus supports episodic memory via interaction with a distributed brain network. Previous experiments using network-targeted noninvasive brain stimulation have identified episodic memory enhancements and modulation of activity within the hippocampal network. However, mechanistic insights were limited because these effects were measured long after stimulation and therefore could have reflected various neuroplastic aftereffects with extended time courses. In this experiment with human subjects of both sexes, we tested for immediate stimulation impact on encoding-related activity of the hippocampus and immediately adjacent medial-temporal cortex by delivering theta-burst transcranial magnetic stimulation (TBS) concurrent with fMRI, as an immediate impact of stimulation would suggest an influence on neural activity. We reasoned that TBS would be particularly effective for influencing the hippocampus because rhythmic neural activity in the theta band is associated with hippocampal memory processing. First, we demonstrated that it is possible to obtain robust fMRI correlates of task-related activity during concurrent TBS. We then identified immediate effects of TBS on encoding of visual scenes. Brief volleys of TBS targeting the hippocampal network increased activity of the targeted (left) hippocampus during scene encoding and increased subsequent recollection. Stimulation did not influence activity during an intermixed numerical task with no memory demand. Control conditions using beta band and out-of-network stimulation also did not influence hippocampal activity or recollection. TBS targeting the hippocampal network therefore immediately impacted hippocampal memory processing. This suggests direct, beneficial influence of stimulation on hippocampal neural activity related to memory and supports the role of theta-band activity in human episodic memory.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available