Alcohol reduces the connection between the amygdala and the prefrontal cortex, so the fear and smart centres don’t communicate as much.

Research people did an experiment, as they often claim to do. It was a suspiciously small sample of participants, as it often is. The difference here was the humanoid laboratory rats being drunk on almost half a litre of alcohol. In fMRI, there was reduced amygdala to prefrontal cortex activity during alcohol intoxication. This suggests reduced connectivity.

Specifically, the decreased amygdala to orbitofrontal cortex interaction messes up the processing and behavioural inhibition around emotional stimuli.

References

1. Gorka, S. M., Fitzgerald, D. A., King, A. C., & Phan, K. L. (2013). Alcohol attenuates amygdala-frontal connectivity during processing social signals in heavy social drinkers: a preliminary pharmaco-fMRI study. Psychopharmacology, 229(1), 141–154. https://doi.org/10.1007/s00213-013-3090-0
2. Rolls, E. T., Cheng, W., & Feng, J. (2020). The orbitofrontal cortex: reward, emotion and depression. Brain communications, 2(2), fcaa196. https://doi.org/10.1093/braincomms/fcaa196