New study shows targeted brain stimulation can block traumatic memory consolidation

A study published in Behaviour Research and Therapy has demonstrated that targeting a specific part of the brain with magnetic stimulation can disrupt the consolidation of traumatic memories, potentially paving the way for new treatments for conditions like anxiety and PTSD.

Researchers have long known that human memories of threats are highly flexible and can be edited. This flexibility has been harnessed by interfering with the memory consolidation process. Techniques such as non-invasive brain stimulation have been used to modify these memories, but the exact mechanisms and optimal timing for intervention have remained unclear.

Led by Simone Battaglia from the University of Bologna in Italy, the research team was particularly interested in the role of the dorsolateral prefrontal cortex (dlPFC) in consolidating threat memories. They hypothesized that this brain region is crucial for the process and that disrupting its activity could prevent the consolidation of traumatic memories.

To test their hypothesis, the team conducted a study involving 72 healthy adult volunteers. The participants were divided into four groups and subjected to a threat-conditioning paradigm. This involved pairing a visual stimulus with an electric shock to create a conditioned threat response. The key intervention was the application of low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) targeting the dlPFC immediately after the threat acquisition phase.

The researchers discovered that participants who received LF-rTMS targeting the dlPFC showed a significant reduction in defensive reactions to the threat stimulus immediately after stimulation, as well as one hour and 24 hours later. In contrast, participants in the control groups, who received either occipital cortex stimulation, delayed dlPFC stimulation (six hours later), or sham stimulation, did not show any reduction in defensive reactions.

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By disrupting the activity of this brain region within the early consolidation period, the researchers were able to prevent the persistence and return of conditioned threat responses. The authors suggest that LF-rTMS could be a powerful tool for interfering with the consolidation of aversive, threat-related memories.

Battaglia and colleagues emphasized the importance of their findings, “unveiling the brain areas necessary for memory consolidation in the context of novel threat learning creates an engaging chance for non-invasive stimulation-based interventions, applicable to mental disorders such as anxiety and post-traumatic stress disorders. In this context, it is crucial to be aware that 20–60% of psychiatric populations show a poor response to classic pharmacological and behavioral therapies, putting a strain on the healthcare system… Thus, specific treatments resulting from new/combined approaches will also lead to a reduction in the financial concerns arising from the cost of psychiatric interventions.”

However, the study did have some limitations. The researchers relied solely on skin conductance response to assess fear responses, which may not capture the full complexity of the emotional and physiological reactions involved. Additionally, the study only administered LF-rTMS to the left dlPFC, leaving open the question of whether similar effects would be observed with stimulation of the right dlPFC.

The study, “Nip it in the bud: Low-frequency rTMS of the prefrontal cortex disrupts threat memory consolidation in humans”, was authored by Simone Battaglia, Claudio Nazzi, Miquel A. Fullana, Giuseppe di Pellegrino, and Sara Borgomaneri.