PIPages
Labs

Bharath Chandrasekaran

Northwestern University, IL·Neuroscience

Why do some adults learn new speech sounds, such as those of a second language, far better than others? And what does the brain's response to sound actually reveal?

Fields

Neuroscience

Psychology

Biomedical Engineering

Topics

auditory neuroscience

speech perception

second language learning

Grants
2 known grants, through Dec 2027

What they work on

  1. Test whether moment-to-moment brain states, driven by noradrenergic, cholinergic and dopaminergic arousal systems, explain individual differences in learning speech sound categories, measured in mice and humans with pupil tracking, neural recordings and behavior.
  2. Use vagus nerve stimulation, a non-invasive way to engage arousal systems, to improve auditory learning, toward a device that pairs pupil-linked arousal monitoring with stimulation.
  3. Characterize the cortex's contribution to the frequency-following response, a scalp brain wave that tracks sound, by recording scalp and intracranial activity in human patients, macaques and guinea pigs.
  4. Compare frequency-following responses to human and animal vocalizations across species with representational similarity analysis, testing the influence of predictability, category relevance and arousal.
  5. Build and validate a computational model of cortex-to-midbrain feedback on the response, using patients with Heschl's gyrus lesions and chemogenetic suppression in animals.

More about the research

Two projects tackle these questions. One explores how shifting brain states during learning explain differences between learners, and how gentle nerve stimulation might boost learning. The other works out where a widely used brain-wave measure of speech processing comes from. Both combine studies in humans and animals.

Why it matters

These projects could lead to simple, cheap and safe tools, such as pupil-guided vagus nerve stimulation, that help adults who struggle to learn a second language or other skills. Clarifying where the frequency-following response comes from could also strengthen its use as a clinical biomarker of speech processing.

Known grants

From NIH and NSF research grants. Labs often have other funding we can't see.

Collaborative Research: NCS-FR: Individual variability in auditory learning characterized using multi-scale and multi-modal physiology and neuromodulation

NSF · Jan 2024 – Dec 2027

Cortical contributions to frequency-following response generation and modulation

NIH · Apr 2014 – Mar 2027

Closest labs

Matthew Leonard

University of California-San Francisco, CA·Neuroscience

Determine how arousal systems that release noradrenaline, acetylcholine and dopamine affect cortical neurons during the pre-sound, sound-encoding and feedback phases of a sound-learning task in mice.

Kevin Sitek

Northwestern University, IL·Neuroscience·Early-career

Use the frequency-following response, a scalp recording of how faithfully early auditory structures encode a sound, to determine when and where auditory-motor interactions occur during self-generated sounds, subcortically or in primary auditory cortex.

Adeen Flinker

New York University, NY·Neuroscience

Map the integration periods, the time windows over which neurons combine sound, across primary and non-primary auditory cortex, using direct cortical recordings in neurosurgical patients.

The school

Northwestern University: 71 labs on PI Pages, $1.3B a year on research, 536 research doctorates a year.

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