To place the tips of the fingers against one's own forehead, as if trying to access something recalcitrant from the brain.
(Derived from "mind meld," coined by the original television series Star Trek, referring to a technique employed by Mr. Spock to access the thoughts and emotions of another being.)
From a prose adaptation of David Mamet's Glengarry Glen Ross:
"...how are you?" Ricky asked, finally noticing George's agitation.
"Fine.... You mean the board? How am I doing on the board?"
"Okay," Ricky said, slightly bewildered. "The board."
"I'm fucked on the board! My mind must be other places," George said, performing a mine meld, "Because I can't... I can't..."
"You can't do what?" Ricky barked impatiently.