Fiend Without A Face (1958)

A scene from Fiend Without a Face in which disembodied brains, initially invisible, but now readily seen, looking for more victims’ necks to wrap their spines around.

Kit Maker: John Dennet

From Wikipedia:

Fiend Without a Face is a 1958 British black-and-white science fiction film directed by Arthur Crabtree. It tells the story of mysterious deaths at the hands of an invisible life-form that steals human brains and spinal columns. The film was based upon Amelia Reynolds Long’s 1930 short story entitled “The Thought Monster” that was originally published in Weird Tales magazine.