Get a whiff of xenon to see what small alteration to electrical properties of the neurons amounts to.

My initial reaction was shock that a heavier-than-air radioactive gas might go into someone's lungs on purpose. It triggers a lot of my "scary danger" heuristics for gases. Googling turned up a bunch of fascinating stuff. Thanks for the surprise! For anyone else interested, educational content includes:

• Since its 1951 report of use in humans, xenon has been viewed as the closest candidate for an ideal anesthetic gas for its superior hemodynamic stability and swift recovery period

• Neuroprotective and neurotoxic properties of the ‘inert’ gas, xenon

• First baby given xenon gas to prevent brain injury

• Sulfur hexafluoride has a similar speed of sound (and hence affect on voice sound) but isn't mind altering

Neat!