A visual cortex origin of trauma memory intrusions: integrated evidence from TMS and fMRI.

BACKGROUND

Intrusive trauma memories - vivid, distressing recollections that occur involuntarily and may feel present - is a defining symptom of post-traumatic stress disorder (PTSD). While traditional models emphasize dysregulation within limbic-prefrontal circuits, emerging evidence implicates visual sensory systems in the formation of trauma-memory intrusions. However, direct causal evidence remains lacking.

METHODS

We combined functional MRI with repetitive transcranial magnetic stimulation (rTMS) to examine the causal role of visual sensory cortices in intrusive memory formation. Healthy participants underwent a trauma-film paradigm, followed by fMRI scanning during memory encoding and a post-encoding resting phase during which spontaneous intrusions were recorded. One group received 1-Hz rTMS targeting early visual cortex (V1/V2); a control group received stimulation at the Vertex. Intrusive memories were recorded over the subsequent 7 days.

RESULTS

rTMS to V1/V2 significantly reduced the frequency, vividness, and emotional intensity of intrusive memories, while preserving recognition of episodic gist. fMRI analyses showed that intrusive episodes were associated with heightened activation and stable neural representations within the occipital visual cortex (OVC). Functional and effective connectivity analyses further revealed that the occurrence of intrusions was predicted by interactions between the middle frontal gyrus (MFG) and OVC. Dynamic causal modeling confirmed direct, bidirectional MFG-OVC interactions that coexisted with, but tracked the intrusion dynamics more closely than, the traditional prefrontal-limbic circuits.

CONCLUSIONS

These findings provide the first causal evidence for the direct involvement of the early visual cortex in trauma-memory intrusions. They highlight the visual system as a novel neuromodulation target for therapeutic intervention on PTSD.