Research

Verbal communication, in particular speech comprehension, relies on a combination of general auditory and speech-specific mechanisms, as well as on their interactions with multimodal and wide-spread neural networks that support other cognitive functions (e.g., attention and decision making). We study the cognitive and neural mechanisms that support language comprehension and verbal communication, in monolingual and bilingual individuals.

Methodologies

We use multiple electrophysiological methodologies, including whole-brain recordings using MEG and EEG, as well as intracranial electrophysiology in clinical settings (iEEG). This combination provides us with the unique opportunity to study human communication across neuronal scales: whole-brain neural dynamics in MEG, and submillimeter spatial resolution of intracranial recordings. Experimentally, we combine the analysis of continuous naturalistic stimuli with targeted hypothesis-driven task and stimulus designs.

Previous Research Projects

Cortical representations of syllables in continuous speech

The continuous speech signal is characterized by prominent temporal modulations of its overall amplitude, reflective of its syllabic structure. In her postdoctoral work at UCSF, Yulia probed how the speech envelope is encoded in the speech cortex using intracranial recordings from neurosurgical patients. They discovered that neuronal populations in speech cortex represent the speech amplitude envelope through encoding of rapid increases in the envelope (acoustic edges). This representation reflects the rate of amplitude change, cueing the timing and stress of syllables (Oganian & Chang, Sci Adv, 2019).
This piece on npr contains a comprehensive summary of this work.

Current Research Projects

Effects of varying speech information rate on neuronal processing

Involved team members: Mara Wolter, Dr. Yulia Oganian

Cognitive and neural representations of speech onsets

Involved team members: Charlotte Mock, Dr. Yulia Oganian

Neural processing of vowel duration

Involved team members: Mara Wolter, Andrey Zyryanov, Harivignesh Ganesan, Dr. Yulia Oganian