“Facephenes”: Brain Stimulation Creates Phantasmal Faces

By Neuroskeptic | November 4, 2017 2:45 pm

Have you ever seen a face on a football?

In a new paper, neuroscientists Gerwin Schalk et al. report that brain stimulation caused a man to experience strange hallucinations. The patient saw faces in everyday objects, including an orange soccer ball and a featureless box. The researchers coined the word “facephenes” to refer to these face-like perceptions.

Schalk et al. studied a 26 year old Japanese man suffering from intractable epilepsy. The patient was implanted with a large number of brain electrodes in order to pin down the source of his seizures. Crucially for Schalk et al., several of the electrodes lay on the fusiform face area (FFA).

The FFA has been a focus of much research to determine whether it is – as the name suggests – a brain area devoted to the perception of faces. While there have been monkey studies previously, Schalk et al. say this is the first human study to focus on the how FFA stimulation affects the perception of non-face objects.

schalk_facephene

It turned out that stimulation of particular points within the left FFA evoked fleeting, face-like imagery that the patient stuggled to describe. The transcript of his running commentary on his experiences makes it clear how subtle the facephenes were:

Stimulation while looking at a Box:
Patient: “It doesn’t change much. But for the first second, just for the very first second after it started I saw an eye, and eye, and a mouth for a bit but I started thinking ‘what is this’? but the next thing I noticed was just looking at this box.”

Stimulation while looking at a Ball:
Patient: “How do I explain this … just like the previous one, I see an eye, an eye and a mouth, sideways.”
Experimenter: “What kind of face was it?”
Patient: “Just now? What’s that cartoon character? … Not sure what, but some sort of cartoon character.”

When the FFA was stimulated while the patient was looking at the face of one of the experimenters, it caused a characteristically Japanese transformation:

Patient: Your facial expression changed.
Experimenter: What changes?
Patient: From your eyes to your mouth, your face kind of changes into an anime character.

This is a striking set of results. The main advance here is that Schalk et al. have shown that FFA stimulation is sufficient to evoke face perception. Previous studies had only shown it to be necessary, by showing that disrupting the FFA impairs face processing. Thus, the evidence that the FFA is causally involved in face perception grows stronger. Still, I suspect that the long debate over the function of this area isn’t over.

Then again, this isn’t the first human FFA stimulation study. Back in 2012, Parvizi et al. carried out a study similar to Schalk et al.’s. They found that FFA stimulation disrupts and distorts face perception, but their patient didn’t report facephenes. So why not? Schalk et al. don’t really discuss the discrepency, saying only that Parvizi et al. “did not systematically test” the effects on non-face perception. Maybe only certain people see facephenes.

One question I had about the results was this: did the patient experience the facephenes as being ‘in’ the objects, such that they became objects-with-faces? Or, alternatively, were the faces ‘on’ the objects – superimposed on them, but seperate from them? The patient’s vague and halting description in the transcripts doesn’t seem to distinguish between these two possibilities.

Schalk et al., though, explicitly describe the facephenes as being “superimposed” on the real world, saying that the stimulation “added a face on top” of the objects. Perhaps it’s a language issue: the transcript is translated from Japanese, so perhaps the original meaning makes it clear that the faces were distinct from the objects.

CATEGORIZED UNDER: faces, papers, select, Top Posts
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  • TLongmire

    Energy is added, entropy increases, then the trickster fairy shows it’s face. https://uploads.disquscdn.com/images/625d39210d59173a74d3d886d71b7b05ffeeb8b4f300609fc7d2c95b5fe6379c.jpg

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    man suffering from intractable epilepsy. The patient was implanted with a large number of brain electrodes” Cannibidiol emulsion sub-lingual as a trial. It often affords deep suppression of epileptiform events without intoxication. It is a revenue threat to Big Pharma.

    Epilepsy Curr. 16(4) 239 (2016), DOI:10.5698/1535-7511-16.4.239
    …The median reduction in monthly motor seizures was 36·5%
    Seizure 21(5) 344 (2012), DOI:10.1016/j.seizure.2012.03.001
    …These results extend the anti-convulsant profile of CBD; when combined with a reported absence of psychoactive effects,
    J. Pharmacol. Exp. Ther. 332(2) 569 (2010), DOI:10.1124/jpet.109.159145
    …” exerted clear anticonvulsant effects with significant decreases in incidence of severe seizures and mortality compared with vehicle-treated animals. Finally, CBD acted with only low affinity at cannabinoid CB1 receptors”

    • John Ohno

      How is this relevant?

      Most studies involving direct electrical stimulation of deep brain structures are performed on epileptics, because intractible epilepsy is one of the few disorders that benefits from substantial brain surgery (severing the corpus collosum) — so it’s convenient to perform experiments while their skulls are open, which would otherwise be an ethical minefield.

      While restrictions on cannabis are unusually strong in Japan, it would be shocking if in the course of going through all available treatments, intractable epileptics in other first-world countries did not also try pot. It’s also pretty naive to think that “big pharma” would not also leverage their budgets and facilities to dominate the production and distribution of synthetic cannibinoids once they are approved for any medical use in a major market.

      There are a *lot* of epilepsy drugs, with different mechanisms of action. All of them are a miracle drug to somebody, but none of them solve all cases. CBD is very unlikely to be an exception — probably, it will be a slight improvement over existing drugs for some people who already respond to treatment, slightly less effective on others, and will treat some fraction of currently-intractible cases, just like every other one of the literally hundreds of anti-convulsants currently available.

      • Kamran Rowshandel

        Have you ever tried CBD? There’s nothing on Earth with a more unpleasant effect than it.

  • LCND

    Below is a quote from

    Electrophysiological studies of human face perception. III: Effects of top-down processing on face-specific potentials
    A Puce, T Allison, G McCarthy – Cerebral Cortex, 1999
    https://academic.oup.com/cercor/article/9/5/445/310738

    See also: https://www.biorxiv.org/content/biorxiv/early/2017/05/26/142786.full.pdf

    We have known about face hallucinations arising from stimulation of this region for almost 20 years.

    https://uploads.disquscdn.com/images/fc06f994f9d10e4ad721e6f29fec64423372987d90679e85c26ae55b8c285f83.png

  • Jenny H

    I would presume that this is similar to the ‘faces’ one sees when dropping off to sleep. Being a ‘doggy’ person, sometimes I see human faces, and sometimes I see dog faces and heads. They are always beautiful and I just which I could draw them.

  • Aina Puce

    It is always tricky to work out the exact content of hallucinations that patients described when their brains are electrically stimulated invasively. One way is to perform the stimulation with a large white board in front of the patient which has a central fixation cross in the center that the patient gazes at during stimulation. The white board itself has lines on it {a bit like a dartboard}. In this way the patient can describe where exactly in their visual field the hallucination occurs, whether it moves (and to where) and so on… Once these ‘baseline’ studies have been performed and the hallucinations have been documented, other testing can be conducted with objects, familiar faces and words so on. In this way, if there is a better chance of determining whether the hallucination is ‘superimposed’ on what is being viewed or whether there is a real distortion to the visual percept being viewed. From our experience, it seems like there is more likely to be a superposition of the hallucination on the visual material. The patients can describe it interfering with what they are trying to see. The interesting thing is that the hallucination is reproducible – one can go back time and time again and stimulate the same pair of electrical contacts and elicit the same phenomenon. In our experience, the hallucinated faces are typically not familiar to the individual.

    • Sys Best

      The pt does not seem to describe a face, rather says ‘eyes and mouth’. It seems to be the feature vector of a perceptron.

      • Aina Puce

        We have also described a patient seeing only an eye. It was with continued stimulation that it became a face. [See the quote from our paper posted by LCND.]

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Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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