Exhibit 3.1

FOURTH AMENDED AND RESTATED

CERTIFICATE OF INCORPORATION OF

VIGIL NEUROSCIENCE, INC.

FIRST: The name of the corporation is: Vigil Neuroscience, Inc. (the “Corporation”).

SECOND: The address of the registered office of the Corporation in the State of Delaware is: 251 Little Falls Drive, City of Wilmington, County of New Castle, Delaware 19808. The name of its registered agent for service of process in the State of Delaware at such address is Corporation Service Company.

THIRD: The purpose of the Corporation is to engage in any and all lawful acts or activities for which corporations may be organized under the General Corporation Law of the State of Delaware (the “DGCL”), as from time to time amended.

FOURTH: The total number of shares of capital stock which the Corporation shall have authority to issue is one thousand (1,000), all of which shares shall be common stock each having a par value of $0.0001. The Corporation may issue fractions of a share of common stock.

FIFTH: In addition to the powers and authority herein before or by statute expressly conferred upon them, the board of directors of the Corporation (the “Board of Directors”) is hereby empowered to exercise all such powers and do all such acts and things as may be exercised or done by the Corporation, subject to the provisions of the DGCL, this Certificate of Incorporation and the bylaws of the Corporation. Election of directors need not be by written ballot unless the bylaws of the Corporation so provide.

SIXTH: In furtherance and not in limitation of the powers conferred by law, subject to any limitations contained in this Certificate of Incorporation, the bylaws of the Corporation may be adopted, amended or repealed by the Board of Directors, but any bylaws adopted by the Board of Directors may be amended or repealed by the stockholders entitled to vote thereon.

SEVENTH: To the fullest extent permitted by the DGCL, no director of the Corporation shall be personally liable to the Corporation or its stockholders for monetary damages for any breach of fiduciary duty as a director, except for liability (a) for any breach of the director’s duty of loyalty to the Corporation or its stockholders, (b) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (c) under Section 174 of the DGCL or (d) for any transaction from which the director derived an improper personal benefit. No amendment to or repeal of this Article Seventh shall apply to or have any effect on the liability or alleged liability of any director of the Corporation for or with respect to any acts or omissions of such director occurring prior to such amendment or repeal.

EIGHTH: The Corporation reserves the right to amend, alter, change or repeal any provision contained in this Certificate of Incorporation, in the manner now or hereafter prescribed by statute, and all rights conferred upon stockholders herein are granted subject to this reservation.

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Vigil Neuroscience, Inc. 8-K