Chinese-Specific Speech Imagery Coding Using High-Density ECoG

Investigation of Chinese-Specific Speech Imagery Encoding and Decoding Using High-Density Electrocorticography

The goal of this study is to investigate whether high-density electrocorticography (ECoG) signals recorded from the surface of the brain can be used to decode neural representations of Mandarin Chinese speech features, including lexical tone, without requiring overt speech movements. The study focuses on the development and evaluation of decoding algorithms based on neural activity recorded during clinically indicated neurosurgical procedures.

The main questions it aims to answer are:

Can high-density ECoG signals be decoded to reconstruct neural representations of Mandarin Chinese speech features, particularly lexical tone?

Can neural activity recorded during silent auditory speech imagery be decoded to reconstruct tone-specific speech representations without actual articulation?

The study includes two groups of adult patients with neurological conditions who require cortical electrode placement as part of clinically indicated care:

A intraoperative high-density ECoG temporary coverage group, enrolling approximately 50 patients with functional-area glioma or drug-resistant epilepsy who undergo awake neurosurgery with temporary high-density ECoG coverage for clinical functional mapping.

A permanent high-density ECoG implantation group, enrolling approximately 10 patients with severe speech or language impairment caused by neurological conditions such as stroke, brain tumors, amyotrophic lateral sclerosis (ALS), or locked-in syndrome, who receive permanent high-density cortical electrode implantation for long-term monitoring.

Participants will:

Complete preoperative clinical assessments as part of standard medical care, including brain imaging, language function evaluation, and routine neurological assessments

Undergo clinically indicated awake neurosurgical procedures during which high-density ECoG electrodes are placed on the cortical surface for clinical functional localization

Perform language-related tasks, such as listening to speech, imagining speech, and limited spoken responses, while brain electrical activity is recorded for approximately 20-30 minutes during surgery, without altering standard surgical procedures

For participants in the permanent implantation group, participate in long-term follow-up visits approximately every 2 weeks or monthly for up to 12 months after surgery, including evaluation of signal quality and research-related analysis and optimization of decoding algorithms

All surgical procedures involving temporary or permanent electrode placement are performed for clinical indications and have been approved through institutional ethical and scientific review. Participation in this study does not alter standard clinical care for the temporary recording group and does not require additional clinical procedures beyond routine treatment.

This research aims to support the long-term development of silent brain-to-speech communication technologies for individuals with severe speech or motor impairments and to improve understanding of how frontal, parietal, and temporal brain regions represent imagined speech in tonal languages such as Mandarin Chinese.

Study Overview

• Status: Recruiting
• Conditions: Stroke; ALS; Aphasia; Dysarthria; Brain Tumor Adult; Speech and Language Disorder; locked-in Syndrome; Epilepsies
• Intervention / Treatment: Procedure: Intraoperative high-density ECoG recording; Procedure: Permanent high-density ECoG implantation

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Feng Yan, MD, PhD; Phone Number: +86 19032580606; Email: yan.feng7@163.com
• Study Contact Backup: Name: Zehao Zhao, Md, PhD; Phone Number: +86 17816872380; Email: zhaozehaox@163.com

Study Locations

• China
  • Zhejiang
    • Hangzhou, Zhejiang, China, 310009
      • Recruiting
      • The Second Affiliated Hospital, Zhejiang University School of Medicine
      • Contact: Feng Yan, MD, PhD; Phone Number: +86 19032580606; Email: yan.feng7@163.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age between 20 and 80 years.
• Ability and willingness to provide informed consent and comply with study procedures.
• No severe preoperative emotional or consciousness disorders that would preclude participation in experimental tasks.
• For patients undergoing intraoperative temporary high-density ECoG coverage: Patients with cerebral eloquent-area gliomas or refractory epilepsy undergoing awake craniotomy as part of standard clinical management.
• For patients undergoing intraoperative temporary high-density ECoG coverage: Lesions involving or adjacent to eloquent brain areas including language, motor, or memory-related regions.
• For patients undergoing intraoperative temporary high-density ECoG coverage: Mild mass effect without severe intracranial hypertension.
• For patients undergoing intraoperative temporary high-density ECoG coverage: Preoperative language function largely preserved, with naming, reading, and language comprehension ≥80% of normal performance.
• For patients undergoing permanent high-density ECoG implantation: Severe speech or language dysfunction caused by stroke, brain tumors, amyotrophic lateral sclerosis (ALS), or locked-in syndrome.
• For patients undergoing permanent high-density ECoG implantation: No substantial improvement after 3-6 months of adequate rehabilitation and disease duration >12 months.
• For patients undergoing permanent high-density ECoG implantation: Structural integrity of speech imagery-related cortices (ventral central lobule, supramarginal gyrus, superior temporal gyrus, middle temporal gyrus, middle frontal gyrus, and inferior frontal gyrus).
• For patients undergoing permanent high-density ECoG implantation: Diagnosis of severe dysarthria or severe motor aphasia, with spontaneous speech score <5/20 on the Aphasia Battery of Chinese (ABC) and auditory comprehension ≥80% of normal levels.

Exclusion Criteria:

• Significant mass effect with severe intracranial hypertension precluding awake craniotomy or electrode implantation.
• Severe neurological dysfunction that would prevent participation in study procedures (except for speech or language impairment in the permanent implantation cohort).
• Contraindications to MRI scanning or awake craniotomy, including incompatible implanted medical devices, severe claustrophobia, or obstructive sleep apnea syndrome.
• Severe psychiatric disorders or cognitive impairment preventing participation in treatment or follow-up assessments (Mini-Mental State Examination score <24).
• Severe systemic medical comorbidities.
• Pregnancy or lactation.
• Refusal or inability to provide informed consent.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intraoperative high-density ECoG temporary coverage; Approximately 50 patients with cerebral eloquent area gliomas or refractory epilepsy will be enrolled. All enrolled patients will undergo awake craniotomy as part of their routine tumor treatment. ① Age between 20 and 80 years; ② Patients with cerebral eloquent area gliomas or refractory epilepsy, with lesions involving or adjacent to eloquent brain areas including language, motor, and memory critical regions; ③ Mild mass effect; ④ No severe language, emotional, or consciousness disorders preoperatively; preoperative language function assessments including naming, reading, and language comprehension abilities must reach 80% of normal levels; ⑤ Informed consent; subjects must demonstrate good willingness and capacity for cooperation.	Procedure: Intraoperative high-density ECoG recording; Electrode implantation is performed via neurosurgical awake craniotomy. Following intraoperative awakening, direct cortical electrical stimulation is applied to localize language functional areas while the subject performs language tasks. Subsequently, high-density electrocorticography is employed to record neural electrical activity. For the temporary coverage group, this enables precise localization of language functional areas; for the permanent implantation group, this facilitates determination of optimal electrode implantation sites.
Experimental: Permanent high-density ECoG implantation; Approximately 10 patients with speech or language dysfunction resulting from stroke, brain tumors, amyotrophic lateral sclerosis (ALS), or locked-in syndrome will be enrolled. ① Age between 20 and 80 years; ② Speech or language dysfunction caused by stroke, brain tumors, ALS, or locked-in syndrome, with no substantial improvement after 3-6 months of adequate rehabilitation training and disease duration >12 months; ③ Speech imagery-related cortices (ventral central lobule, supramarginal gyrus, superior temporal gyrus, middle temporal gyrus, middle frontal gyrus, and inferior frontal gyrus) essentially intact; ④ No emotional or consciousness disorders preoperatively; preoperative language assessment diagnosis of severe dysarthria or severe motor aphasia (Aphasia Battery of Chinese, ABC spontaneous speech score <5/20), with auditory comprehension reaching >80% of normal levels; ⑤ Informed consent; subjects must demonstrate good willingness and capacity for cooperation.	Procedure: Intraoperative high-density ECoG recording; Electrode implantation is performed via neurosurgical awake craniotomy. Following intraoperative awakening, direct cortical electrical stimulation is applied to localize language functional areas while the subject performs language tasks. Subsequently, high-density electrocorticography is employed to record neural electrical activity. For the temporary coverage group, this enables precise localization of language functional areas; for the permanent implantation group, this facilitates determination of optimal electrode implantation sites.; Procedure: Permanent high-density ECoG implantation; In the permanent implantation group, subjects demonstrating satisfactory intraoperative electrode signals who voluntarily consent to permanent electrode implantation will undergo permanent electrode placement and long-term follow-up. Postoperative follow-up is conducted biweekly or monthly, encompassing: signal quality assessment, analysis of neural encoding mechanisms during speech imagery, and calibration of brain-computer interface decoding algorithms. The trial duration for each subject is approximately 13 months.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Electrode Signal Quality Assessment	Electrode reliability over time is evaluated through electrode impedance, signal-to-noise ratio (SNR), and responsive channel proportion. Low electrode impedance, high SNR, and high responsive channel proportion indicate good signal quality reliability of the device.	through study completion, an average of 2 years
Decoding Classification Accuracy	The proportion of correctly classified targets by the decoding model is evaluated for recognition categories (e.g., syllables, words, or sentences).	through study completion, an average of 2 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Encoding Model Analysis	An L2-regularized time-receptive-field (TRF) model (time window: -400 to 400 ms) with parallel five-fold cross-validation is employed to calculate the coefficient of determination (R²) between neural signals and AKT, phonemic features, and Mel-spectrogram, respectively, enabling comprehensive evaluation of the encoding capacity of fronto-parieto-temporal neurons for articulatory and acoustic features.	through study completion, an average of 2 years

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adverse Event Incidence Rate	All adverse events are collected through active monitoring (intraoperative observation, postoperative daily ward rounds), adverse event report forms, imaging examinations, laboratory tests (routine blood test, cerebrospinal fluid analysis), and patient complaints. Incidence rates are calculated separately for each adverse event category (intraoperative electrical stimulation-related, device-related, drug-related, pregnancy-related, etc.) using the formula: number of patients experiencing specific adverse events divided by total enrolled patients multiplied by 100%.	through study completion, an average of 2 years

Collaborators and Investigators

• Sponsor: Second Affiliated Hospital, School of Medicine, Zhejiang University
• Investigators: Principal Investigator: Feng Yan, Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University

Publications and helpful links

General Publications

• Metzger SL, Littlejohn KT, Silva AB, Moses DA, Seaton MP, Wang R, Dougherty ME, Liu JR, Wu P, Berger MA, Zhuravleva I, Tu-Chan A, Ganguly K, Anumanchipalli GK, Chang EF. A high-performance neuroprosthesis for speech decoding and avatar control. Nature. 2023 Aug;620(7976):1037-1046. doi: 10.1038/s41586-023-06443-4. Epub 2023 Aug 23.
• Lu J, Li Y, Zhao Z, Liu Y, Zhu Y, Mao Y, Wu J, Chang EF. Neural control of lexical tone production in human laryngeal motor cortex. Nat Commun. 2023 Oct 30;14(1):6917. doi: 10.1038/s41467-023-42175-9.
• Liu Y, Zhao Z, Xu M, Yu H, Zhu Y, Zhang J, Bu L, Zhang X, Lu J, Li Y, Ming D, Wu J. Decoding and synthesizing tonal language speech from brain activity. Sci Adv. 2023 Jun 9;9(23):eadh0478. doi: 10.1126/sciadv.adh0478. Epub 2023 Jun 9.

Study record dates

Study Major Dates

• Study Start (Estimated): March 15, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: March 4, 2026
• First Submitted That Met QC Criteria: March 9, 2026
• First Posted (Actual): March 10, 2026

Study Record Updates

• Last Update Posted (Actual): March 10, 2026
• Last Update Submitted That Met QC Criteria: March 9, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: speech production; speech imagery; Chinese Mandarin; neural encoding; speech decoding
• Additional Relevant MeSH Terms: Neurologic Manifestations; Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Neuromuscular Diseases; Neurobehavioral Manifestations; Communication Disorders; Paralysis; Speech Disorders; Articulation Disorders; Quadriplegia; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Communication; Verbal Behavior; Locked-In Syndrome; Stroke; Epilepsy; Aphasia; Language Disorders; Dysarthria; Speech
• Other Study ID Numbers: 2025-1259

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The human patient data relevant to this study are accessible under restricted access according to our IRB protocol.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No