A bug doesn't have to be crawling on your skin for you to feel that itchy sensation.

Living in New York City, I occasionally see local news headlines and hear stories from friends of friends about the horrors of bed bugs. Although I have yet to face the nightmarish ordeal myself, I do have the same unpleasant experience whenever the topic comes up: a sudden overwhelming itching sensation on my skin.

I know I’m not alone. Apparently it’s not uncommon to feel the urge to scratch when you talk or think about bugs. And in fact, there are even terms to describe this specific phenomenon.

So why exactly do conversations or thoughts about creepy crawly critters cause an itching sensation, even in the absence of any actual bugs? And is there anything you can do about this phenomenon? HuffPost asked some experts to break it down.

What’s happening in our brains and bodies when we talk or think about bugs?

“The brain doesn’t just process reality ― it constructs it,” Dr. Shaheen E. Lakhan, a board-certified neurologist, told HuffPost. “When you hear about bugs crawling on someone’s scalp or imagine bedbugs in a mattress, your brain activates the same neural circuits as if it were happening to you. This is called ‘contagious itch,’ and it’s driven by a blend of somatosensory activation, emotional processing and mirror neuron activity.”

He explained that our brains can generate sensations even when there’s no physical stimulus, so a bug doesn’t have to be crawling on your skin for you to feel an itch. Instead, you can process a visual input (e.g., seeing someone else scratch) or auditory cue (hearing about insects), or it could even be purely cognitive, like when you imagine bedbugs.

“When you hear about bugs on someone’s scalp, your brain doesn’t just register the words,” Lakhan said. “It activates the somatosensory cortex, the part of the brain responsible for processing bodily sensations like touch, temperature and pain. This activation occurs as if there were actual bugs on your scalp. It’s a ‘simulated’ somatosensory experience, demonstrating that the brain can generate these feelings internally, independent of direct external stimulation.”

The phenomenon can be understood as a form of top-down processing, in which the brain’s higher-level cognitive and emotional functions ― like memories and other prior knowledge and experience ― influences sensory perception. (This is in contrast to bottom-up processing, in which the brain takes in basic sensory details to build higher level understanding.)

Psychologists have also used the terms psychogenic itching, psychogenic formication and psychogenic pruritus to describe itchy sensations........

© HuffPost