Other Psychological Responses to Brain Stimulation

Following are some responses to brain stimulation that Penfield documented.

What sorts of psychological responses did Penfield trigger with direct brain stimulation?

Vocalization A person will make a moaning sound or other vocalization when the precentral gyrus at the top of the brain is stimulated.

Movement Leg or arm movements are a common reaction to stimulation of the motor cortex (the area represented in the homunculus). An "intelligent woman" stated, "my leg moved itself." Sometimes the patient can suppress a movement triggered by brain stimulation. Other times stimulation results in "movement over which [the patient] has no control."

Music A musician heard a song from the musical Guys and Dolls when his temporal lobe was stimulated.

Auditory illusions A number of patients experienced a feeling that sounds in the environment were growing louder, or more far away, or occurring faster or slower.

Visual constructions One man saw "A man and a dog walking." Another saw "someone coming towards me as though he was going to hit me."

Spatial illusions Stimulation of the non-dominant hemisphere made things seem nearer, farther away, or distorted in space. Also common was the labyrinthine illusion, a feeling that the body had changed position in space.

Odors and tastes Some patients reported bitter tastes or disagreeable odors upon brain stimulation

Forced thoughts Patients often had "strange thoughts...difficult to explain" such as "a feeling that I had told somebody or other to do this or that."

Emotions Patients sometimes responded to brain stimulation with powerful feelings of nameless dread, fear, loneliness, remoteness, or disgust, other times with puzzlement or with laughter.

If the brain is involved in constructing the mind, then it should not surprise us that such a wide variety of experiences can be triggered by electrical stimulation of the exposed cortex. After all, every experience is produced by the brain, in the opinion of modern neuroscientists.


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