Media Images

Caption

X-ray showing electrodes that surgeons use to find and remove the source of seizures (to cure epilepsy), while sparing the source of mental functions like language. This is a composite image: the face portion was swapped in from a different person’s x-ray, to protect the privacy of the patient.

In the present study, recordings when patients spoke words revealed that one small part of the brain engages in processing the identity, structure, and sounds of words, separately and in a quick sequence.

Credit

Illustration: Ned T. Sahin, PhD

Click image for full-size.

IMPORTANT NOTE: Electrodes are never implanted just for research!! Electrodes are only placed in people’s brains as part of existing and accepted surgical practice. We then get patients’ consent to also record from these electrodes for research purposes.

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Brain scan showing electrodes that surgeons use to find and remove the source of seizures (to cure epilepsy), while sparing the source of mental functions like language.

[The patient in the x-ray above had one type of electrodes: sub-dural grid electrodes, which are a flat sheet of electrode contacts that are placed directly against the brain surface. The patient in this picture, at left, had a different type of electrodes implanted (different surgeon and hospital): these electrodes are called depth electrodes, and are long thin probes with 8 separate recording contacts along their length.]

In the present study, recordings when patients spoke words revealed that one small part of the brain processes the identity, structure, and sounds of words, separately and in a quick sequence.

Credit

Illustration: Ned T. Sahin, PhD. Brain Image Reconstruction: Sean McInerney.

Caption

Same as above.

Credit

Illustration: Ned T. Sahin, PhD. Brain Image Reconstruction: Sean McInerney.

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Same as above.

Credit

Illustration: Ned T. Sahin, PhD

Caption

Direct recordings from sets of brain cells revealed that three fundamentally distinct aspects of language (meaning, structure, and word sounds) are computed in a small part of the brain and in a tightly-timed sequence.

Explanation of the drawing: The stylized waveform symbolizes the 3-component LFP (local field potential) brain wave that was the core result of the paper. It is a representation of the average electrical signal (vertical axis is voltage) over time. The total waveform represents about 1 second. The stick-figure cartoon of a man on the first LFP component represents the meaning of the word (“walk”), since that first component was associated with the lexical features (roughly, meaning) of the word. The next component was associated with the grammatical structure of the word to be spoken, for instance “walk” plus the ending “-ed” to signify the past tense. The final component was associated with phonology or the sound form of the word, so in this drawing it has the word pronunciation “wokt”.

The stylized head is reconstructed from MRI data. The brain is the actual brain of the patient, but the face is of a separate volunteer, to protect patient confidentiality.

Credit

Illustration: Ned T. Sahin, PhD

Caption

Same as above.

Credit

Illustration: Ned T. Sahin, PhD

Caption

Same as above.

Credit

Illustration: Ned T. Sahin, PhD. Brain Image Reconstruction: Sean McInerney.

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[Collection of images: Click individually, for the high-resolution versions.]

Three-dimensional composite brain scan images showing the entry points of thin electrode arrays that are implanted to guide surgery to cure epilepsy.

Variants show different numbers of the electrodes for illustrative purposes, and have different color schemes. 3D barrel-like structures are the housings sitting outside the skull where the electrodes enter through the skull. The electrodes themselves are in some cases superimposed, simulating how they enter into the brain in these patients. I can generate permutations of the images if you don’t find one that suits your publication or web site.

Credit

Illustration: Ned T. Sahin, PhD

Caption

Brain images: Same as above, but with the head rotated to another angle (any is possible, if you want a different one).

Portrait: Paul Broca, who discovered the language-related brain region known as Broca’s area 150 years ago. The function of the region has been hotly debated since but has not been resolved. The present method revealed a level of organization not previously detectable, and the fact that three distinct linquistic processes overlap spatially may account for confusion over the region’s function in the past.

Credit

Illustration: Ned T. Sahin, PhD. [Image of Broca was in public domain on several web sites.]

Caption

Mug shot of first author Ned T. Sahin, in case a face shot might be desired for an article on this paper. Photos of other authors should be on their web sites – see my Collaborators page for links.

Credit

Ned T. Sahin, PhD.

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Another mug shot.

Credit

Ned T. Sahin, PhD.