<PAGE>

                                    COCENSYS, INC.                  EXHIBIT 10.3
                                EXECUTIVE OFFICERS'
                          CHANGE OF CONTROL SEVERANCE PLAN
                                          
                                    INTRODUCTION

     The CoCensys, Inc. Executive Officers' Change of Control Severance Plan 
was adopted by the Board of Directors (the "Board") of CoCensys, Inc., a 
Delaware corporation (the "Company"), on December 16, 1997.  The Plan is 
intended to provide Executive Officers who are Participants in the Plan and 
whose employment terminates during the period beginning three (3) months 
prior to a Change of Control and ending fifteen (15) months following a 
Change of Control with the Severance Benefits specified herein. This Plan 
document is also the Summary Plan Description for the Plan.

     Certain capitalized terms used in the Plan are defined in Article 9.
                                          
                       ARTICLE 1 -- ESTABLISHMENT OF THE PLAN

     As of the Effective Date, the Company hereby establishes a severance 
plan to be known as the "Executive Officers' Change of Control Severance 
Plan" (the "Plan"), as set forth herein.  The benefits provided by the Plan 
shall be available to all Participants.
                                          
                              ARTICLE 2 -- ELIGIBILITY

     2.1  PARTICIPATION.  Each Executive Officer whom the Board or the 
Compensation Committee of the Board shall from time to time designate as such 
shall be a participant in the Plan (a "Participant").  Any employee holding 
the title of President, Chief Executive Officer, Vice President, or General 
Counsel shall be considered to be an Executive Officer for purposes of 
eligibility under the Plan without further action by the Board or the 
Compensation Committee of the Board.

     2.2  DURATION OF PARTICIPATION.  A Participant shall cease to be a 
Participant in the Plan when such Participant ceases to be a designated 
Executive Officer; PROVIDED, HOWEVER, that if such Participant is then 
entitled to payment of Severance Benefits, such Participant shall remain a 
Participant in the Plan until the full amount of the Severance Benefits has 
been paid to such Participant.
                                          
                           ARTICLE 3 -- SEVERANCE BENEFITS

          3.1  RIGHT TO SEVERANCE BENEFITS.  A Participant shall be entitled 
to receive the benefits from the Company set forth in Section 3.2 (the 
"Severance Benefits") if, within the period beginning three (3) months prior 
to a Change of Control and ending fifteen (15) months following a Change of 
Control (the "Coverage Period"), the Participant's employment by the Company:

                                       1.
<PAGE>


          (a)  shall be involuntarily terminated by the Company without 
Cause; or

          (b)  shall be voluntarily terminated by the Participant on account 
of an event constituting Constructive Termination.

     3.2  DETERMINATION OF SEVERANCE BENEFITS.  If, after a Change of 
Control, any Participant has a right to receive Severance Benefits pursuant 
to Section 3.1 above, Severance Benefits shall be determined as follows:

          (a)   The Participant shall receive a Severance Payment for the 
number of months set forth below ( the "Severance Payment Period"):
<TABLE>
<CAPTION>
          Participant                        Severance Payment Period
          -----------                        ------------------------
          <S>                                <C>
          Chief Executive Officer/President       24 months
          Vice President/General Counsel          12 months
</TABLE>

          (b)   The Participant shall receive a Target Bonus through the end 
of the Severance Payment Period. Therefore, if the Participant's Severance 
Payment Period is twelve (12) months, then the Participant shall receive an 
amount equal to his or her Target Bonus, and if the Severance Payment Period 
is twenty four (24) months, then the Participant shall receive an amount 
equal to twice his or her Target Bonus.

          (c)  The unvested portion of any stock options issued under the 
Option Plans and held by the Participant on the Date of Termination shall be 
fully vested and exercisable as of the later of: (i) the date of the Change 
of Control or (ii) the Date of Termination.  Such options shall remain 
exercisable until the earlier of (i) the expiration of the original full term 
of the option or (ii) two (2) years following the expiration of the Severance 
Payment Period. 

          (d)  Each Participant who is enrolled in a health or dental plan 
sponsored by the Company may be eligible to continue coverage under such 
health or dental plan (or to convert to an individual policy), at the time of 
the Participant's termination of employment under the Consolidated Omnibus 
Budget Reconciliation Act of 1985 ("COBRA").  The Company will notify the 
individual of any such right to continue health coverage at the time of 
termination.  The Company will continue to pay its share of the Participant's 
health insurance premiums until the earliest of: (i) eighteen (18) months 
after the Date of Termination, (ii) such time as the Participant becomes 
eligible to participate in another employer's health insurance plan, or (iii) 
the termination of the Severance Payment Period; PROVIDED THAT the 
Participant elects to continue coverage under COBRA and timely pays the 
Participant's portion of the premiums (the "COBRA Period").  No provision of 
this Plan will affect the continuation coverage rules under COBRA, except 
that the Company's payment of any applicable insurance premiums during the 
COBRA Period will be credited as payment by the Participant for purposes of 
the Participant's payment required under COBRA.  Therefore, the period during 
which an Participant must elect to continue the Company's group medical or 
dental coverage at his or her own expense under COBRA, the length of time 
during which COBRA coverage will be made available to the Participant, and 
all other rights and obligations of the Participant under COBRA (except the 

                                       2.
<PAGE>

obligation to pay insurance premiums that the Company pays during the COBRA 
Period) will be applied in the same manner that such rules would apply in the 
absence of this Plan.  At the conclusion of the COBRA Period, the Participant 
will be responsible for the entire payment of premiums required under COBRA 
for the duration of the COBRA period.

     For purposes of this Section 3.2(d), applicable premiums that will be 
paid by the Company during the Severance Payment Period shall not include any 
amounts payable by the Participant under the Company's Section 125 health 
care reimbursement plan, which amounts, if any, are the sole responsibility 
of the Participant.

     3.3  TIME OF SEVERANCE PAYMENT.  The Company reserves the right to 
determine whether the Severance Benefits under the Plan will be paid in a 
single sum or in installments and to choose the timing of such payments, 
provided, however, that all payments under this Plan will be completed within 
a period of time following a Participant's Date of Termination not exceeding 
the Severance Payment Period. Notwithstanding the foregoing, the 
Participant's Target Bonus payment under Section 3.2(b) shall be paid as 
follows: (i) in a lump sum no later than thirty (30) days following the Date 
of Termination if the Participant's Severance Payment Period is twelve (12) 
months, or (ii) in two equal installments, with the first installment no 
later than thirty (30) days following the Date of Termination and the second 
installment no later than thirteen (13) months following the Date of 
Termination, if the Participant's Severance Payment Period is twenty four 
(24) months. If a terminating employee is indebted to the Company at his or 
her Date of Termination, the Company reserves the right to offset any 
Severance Benefits under the Plan by the amount of such indebtedness. In no 
event shall payment of any Plan benefit be made prior to the Participant's 
Date of Termination.

     3.4  NO MITIGATION.  The Participant shall not be required to mitigate 
the amount of the Severance Benefits by seeking other employment or 
otherwise, and, subject to Section 3.2(d), any amount earned by the 
Participant as the result of employment by another employer after the Date of 
Termination shall not reduce the amount of the Severance Benefit.

     3.5  MAXIMUM BENEFIT OFFSETS AND WITHHOLDING.  In the event of a Change 
of Control, (i) the Severance Benefits are in lieu of any other benefit 
provided under any other group severance plan of the Company and (ii) 
Severance Benefits shall be reduced by the amount of any payment to which the 
Participant is entitled under any individual severance agreement then in 
effect between the Participant and the Company.  In addition, the Company 
shall withhold appropriate federal, state, local and foreign income and 
employment taxes from any payments hereunder.

     3.6  NOTICE OF TERMINATION.  Any termination by the Company for Cause or 
by the Participant on account of Constructive Termination shall be 
communicated by Notice of Termination to the other party hereto given by hand 
delivery or by registered or certified mail, return receipt requested, 
postage prepaid, if to the Participant, then to the Participant at the 
Participant's address as set forth in the Company's records, and, if to the 
Company, to CoCensys, Inc., 201 Technology Drive, Irvine, California 92618.  
Any notices given pursuant to this Section 3.6 shall be effective on the 
earlier of the date on which such notice is actually received by the 

                                       3.
<PAGE>

addressee or the date that is three days after such notice is sent by the 
addressor.  For purposes of the Plan, a "Notice of Termination" means a 
written notice which (i) indicates the specific termination provision in the 
Plan relied upon and (ii) if the Date of Termination, as defined below, is 
other than the date of receipt of such notice, specifies the termination date 
(which date shall be not more than fifteen (15) days after the giving of such 
notice).   The failure by the Company or the Participant to set forth in the 
Notice of Termination any fact or circumstance which contributes to a showing 
of Cause or of Constructive Termination shall not waive any right of the 
Company or of the Participant, respectively, hereunder or preclude the 
Company or the Participant, respectively, from asserting such fact or 
circumstance in enforcing its, his or her rights hereunder.

     3.7  DATE OF TERMINATION.  "Date of Termination" means the date of 
receipt of the Notice of Termination or any later date specified therein, as 
the case may be; PROVIDED, HOWEVER, that (i) if the Participant's employment 
is terminated by the Company other than by reason of death or Disability, or 
for Cause, the Date of Termination shall be the date on which the Company 
notifies the Participant of such termination and (ii) if the Participant's 
employment is terminated by reason of death or Disability, the Date of 
Termination shall be the date of death or determination of Disability 
pursuant to Section 9.5, as the case may be.

     3.8  SPECIAL EXCEPTION.  No benefit shall be payable hereunder solely 
because a Participant's employment terminates because the Company or a 
subsidiary, a division or other operating assets thereof is sold after a 
Change of Control if:

          (a)  The purchaser is contractually obligated to offer the 
Participant a comparable or better job without relocation; and

          (b)  The purchaser is contractually obligated to maintain a plan at 
least equivalent to this Plan.

     3.9  CERTAIN REDUCTION OF PAYMENTS. 

          (a)  Anything in the Plan to the contrary notwithstanding, in the 
event that any payment, distribution or other benefit provided by the Company 
to or for the benefit of a Participant (whether paid or payable or provided 
or to be provided pursuant to the terms of the Plan or otherwise) (a 
"Payment") would (i) constitute a "parachute payment" within the meaning of 
Section 280G of the Code and (ii) but for this Section 3.9, be subject to the 
excise tax imposed by Section 4999 of the Code (the "Excise Tax"), then, in 
accordance with this Section 3.9, such Payments shall be reduced to the 
maximum amount that would result in no portion of the Payments being subject 
to the Excise Tax, but only if and to the extent that such a reduction would 
result in the Participant's receipt of Payments that are greater than the net 
amount the Participant would receive (after application of the Excise Tax) if 
no reduction is made.  The amount of required reduction, if any, shall be the 
smallest amount so that the Participant's net proceeds with respect to the 
Payments (after taking into account payment of any Excise Tax and all 
federal, state and local income, employment or other taxes) shall be 
maximized.  If, notwithstanding any reduction described in this Section 3.9 
(or in the absence of any such reduction), the IRS determines that a Payment 
is subject to the Excise Tax (or subject to a

                                       4.
<PAGE>

different amount of the Excise Tax than determined by the Company or the 
Participant), then Section 3.9(c) shall apply.  If the Excise Tax is not 
eliminated pursuant to this Section 3.9, the Participant shall pay the Excise 
Tax.

          (b)   All determinations required to be made under this Section 3.9 
shall be made by the Company's independent auditors.  Such auditors shall 
provide detailed supporting calculations both to the Company and the 
Participant.  Any such reasonable determination by the Company's independent 
auditors shall be binding upon the Company and the Participant.  The 
Participant shall determine which and how much of the Payments, including 
without limitation any option acceleration benefits provide under this Plan 
or any option ("Option Benefits"), as the case may be, shall be eliminated or 
reduced consistent with the requirements of this Section 3.9, provided that, 
if the Participant does not make such determination within ten business days 
of the receipt of the calculations made by the Company's independent 
auditors, the Company shall elect which and how much of the Option Benefits 
or other Payments, as the case may be, shall be eliminated or reduced 
consistent with the requirements of this Section 3.9 and in the following 
order: payments of the Target Bonus under Section 3.2(b), Severance Payments 
under Section 3.2(a), and option acceleration as described in Section 3.2(c), 
and then the Company shall notify the Participant promptly of such election.  
Within five business days thereafter, the Company shall pay to or distribute 
to or for the benefit of the Participant such amounts as are then due to the 
Participant under the Plan.

          (c)  As a result of the uncertainty in the application of Section 
280G of the Code at the time of the initial determination by the Company's 
independent auditors hereunder, it is possible that Option Benefits or other 
Payments, as the case may be, will have been made by the Company which should 
not have been made ("Overpayment") or that additional Option Benefits or 
other Payments, as the case may be, which will not have been made by the 
Company could have been made ("Underpayment"), in each case, consistent with 
the calculations required to be made hereunder.  In the event that the 
Company's independent auditors, based upon the assertion of a deficiency by 
the IRS against the Participant or the Company which the Company's 
independent auditors believe has a high probability of success, determine 
that an Overpayment has been made, any such Overpayment paid or distributed 
by the Company to or for the benefit of the Participant shall be treated for 
all purposes as a loan AB INITIO to the Participant which the Participant 
shall repay to the Company together with interest at the applicable federal 
rate provided for in Section 7872(f)(2) of the Code; PROVIDED, HOWEVER, that 
no such loan shall be deemed to have been made and no amount shall be payable 
by the Participant to the Company if and to the extent such deemed loan and 
payment would not either reduce the amount on which the Participant is 
subject to tax under Section 1 and Section 4999 of the Code or generate a 
refund of such taxes.  In the event that the Company's independent auditors, 
based upon controlling precedent or other substantial authority, determine 
that an Underpayment has occurred, any such Underpayment shall be promptly 
paid by the Company to or for the benefit of the Participant together with 
interest at the applicable federal rate provided for in Section 7872(f)(2) of 
the Code.

                                       5.
<PAGE>

                  ARTICLE 4 -- PAYMENTS TO AND FROM THE PLAN

     The benefits under the Plan shall be paid from the general funds of the 
Company, and the Participants shall be no more than unsecured general 
creditors of the Company. 
                                          
                 ARTICLE 5 -- OTHER RIGHTS AND BENEFITS NOT AFFECTED

     5.1  NONEXCLUSIVITY.  Nothing in the Plan shall prevent or limit any 
Participant's continuing or future participation in any benefit, bonus, 
incentive or other plans, programs, policies or practices provided by the 
Company and for which a Participant may otherwise qualify, nor shall anything 
herein limit or otherwise affect such rights as any Participant may have 
under any stock option or other agreements with the Company; PROVIDED, 
HOWEVER, that in accordance with Section 3.5, in the event of a Change of 
Control, the Severance Payments hereunder shall be in lieu of any other 
severance payments to which any Participant may otherwise be entitled, 
including without limitation, under any employment contract or severance 
plan.  Except as otherwise expressly provided herein, amounts which are 
vested benefits or which a Participant is otherwise entitled to receive under 
any plan, policy, practice or program of the Company at or subsequent to the 
Date of Termination shall be payable in accordance with such plan, policy, 
practice or program.

     5.2  EMPLOYMENT STATUS.  The Plan does not constitute a contract of 
employment or impose on any Participant or the Company any obligation to 
retain any Participant as an employee, to change the status of the 
Participant's employment, or to change the Company's policies regarding 
termination of employment.
                                          
                          ARTICLE 6 -- SUCCESSOR TO COMPANY

     The Plan shall be binding upon any successor or assignee, whether direct 
or indirect, by purchase, merger, consolidation or otherwise, to all or 
substantially all the business or assets of the Company, and any such 
successor or assignee shall be required to perform the Company's obligations 
under the Plan, in the same manner and to the same extent that the Company 
would be required to perform if no such succession or assignment had taken 
place.  In such event, the term "Company," as used in the Plan, shall mean 
the Company as hereinafter defined and any successor or assignee to the 
business or assets which by reason hereof becomes bound by the terms and 
provisions of the Plan.
                                          
                       ARTICLE 7 -- NON-ALIENATION OF BENEFITS

     No benefit hereunder shall be subject to anticipation, alienation, sale, 
transfer, assignment, pledge, encumbrance or charge, and any attempt to do so 
shall be void.
                                          
                   ARTICLE 8 -- LEGAL CONSTRUCTION AND ARBITRATION

     8.1  APPLICABLE LAW. This Plan is intended to be governed by and shall 
be construed in accordance with the Employee Retirement Income Security Act 
of 1974 ("ERISA") and, to the extent not preempted by ERISA, the laws of the 
State of California.

                                       6.
<PAGE>

     8.2  ARBITRATION.  Any and all disputes or controversies, whether of law 
or fact of any nature whatsoever, arising from or respecting the application 
of the Plan to any Participant shall be decided by arbitration by the 
American Arbitration Association in accordance with the rules and regulations 
of that Association, or by any other arbitration body mutually agreed upon by 
the parties.  Pre-arbitration discovery shall be permitted at the request of 
either party to a dispute under appropriate protection for proprietary and 
confidential business information.

     The arbitrators shall be selected as follows:  the Company and the 
Participant who is a party to the dispute shall each select one independent, 
qualified arbitrator and the two arbitrators so selected shall select the 
third arbitrator. The Company reserves the right to disqualify any individual 
arbitrator who shall be employed by or affiliated with a competing 
organization.

     Arbitration shall take place in Irvine, California, or any other 
location mutually agreeable to the parties.  At the request of either party, 
arbitration proceedings will be conducted in the utmost secrecy and, in such 
case, all documents, testimony and records shall be received, heard and 
maintained by the arbitrators in secrecy under seal, available for inspection 
only by the parties to the arbitration, their respective attorneys, and their 
respective expert consultants or witnesses who shall agree, in advance and in 
writing, to receive all such information confidentially and to maintain such 
information in secrecy, and make no use of such information except for the 
purposes of the arbitration, until such information shall become generally 
known.

     The arbitrators, who shall act by majority vote, shall be able to decree 
any and all relief of an equitable nature, including but not limited to such 
relief as a temporary restraining order, a temporary injunction, or a 
permanent injunction, and shall also be able to award damages, with or 
without an accounting and costs. The decree or judgment of an award rendered 
by the arbitrators may be entered and enforced in any court having 
jurisdiction over the parties.

     Reasonable notice of the time and place of arbitration shall be given to 
persons other than the parties, if such notice is required by law, in which 
case such persons or their authorized representatives shall have the right to 
attend or participate in the arbitration hearing in such manner as the law 
shall require.

     If any action is necessary to enforce or interpret the application of 
the Plan to a Participant, the prevailing party shall be entitled to 
reasonable attorney's fees, costs, and necessary disbursements in addition to 
any other relief to which that party may be entitled.
                                          
                              ARTICLE 9 -- DEFINITIONS

     For purposes of the Plan, the following terms shall have the meanings 
set forth below.

     9.1   "CAUSE" shall mean: (a) an intentional act that materially injures 
the Company; (b) the intentional refusal or failure to follow the lawful and 
reasonable directions of the Board of Directors or the directions of any 
individual to whom the Participant reports; (c) the willful and habitual 
neglect of duties; or (d) the conviction of a felony involving moral 
turpitude which is reasonably likely to inflict or has inflicted material 
injury on the Company; PROVIDED that the

                                       7.
<PAGE>

Participant did not cure such misconduct within thirty (30) days following 
receipt of written notice of such misconduct from the Company.

     9.2  "CHANGE OF CONTROL" shall be deemed to have occurred at any of the 
following times:

           (a)  Upon the adoption by the stockholders of the Company of a 
plan of dissolution, liquidation, or sale or distribution of substantially 
all of the assets or operations of the Company;

          (b)  Upon stockholder approval of a reorganization, merger, 
consolidation or other combination of the Company with one or more 
corporations as a result of which the Company will not be a surviving 
corporation and the stockholders of the Company immediately prior to the 
transaction will own beneficially less than sixty percent (60%) of the then 
outstanding shares of the equity securities of the controlling entity 
immediately following consummation of the transaction;

          (c)  Upon stockholder approval of a reorganization, merger, 
consolidation or other combination of the Company with one or more 
corporations as a result of which the Company will be a surviving 
corporation, but pursuant to which a person (as defined in Section 3(a)(9) 
and 14(d)(2) of the Securities Exchange Act of 1934, as amended (the 
"Exchange Act")) or group of persons will acquire the beneficial ownership of 
forty percent (40%) or more of the equity securities of the Company 
immediately following consummation; or

          (d)  At such time that, in connection with a tender offer or 
exchange offer for any shares of the Company's outstanding common stock (or 
securities convertible into common stock) or other sale of any such 
securities by stockholders of the Company, a person or group of persons owns 
beneficially thirty-three percent (33%) or more of the outstanding common 
stock of the Company.

          For purposes of this Section 9.2, a "person" shall exclude (i) the 
Company, (ii) any subsidiary of the Company, (iii) any trustee or other 
fiduciary holding securities under an employee benefit plan of the Company, 
or (iv) any company owned, directly or indirectly, by the stockholders of the 
Company in substantially the same proportion as their ownership of stock of 
the Company prior to the consummation of the transaction.

     9.3  "COMPANY" means CoCensys, Inc., a Delaware corporation, and any 
successor as provided in Article 6 hereof.

     9.4  "DATE OF TERMINATION" has the meaning set forth in Section 3.7.

     9.5  "DISABILITY" means permanent and total disability as defined in 
Section 22(e)(3) of the Internal Revenue Code of 1986, as amended.

     9.6  "EFFECTIVE DATE" shall mean January 1, 1998.

                                       8.
<PAGE>

     9.7  "EXECUTIVE OFFICER" means the Chief Executive Officer, the 
President, any Vice President and the General Counsel of the Company.

     9.8  "CONSTRUCTIVE TERMINATION" means (i) the assignment of duties and 
responsibilities which result in a diminution of position or function (but 
not merely a change in title or reporting relationships); (ii) the reduction 
in base salary by more than ten percent (10%); (iii) a material reduction in 
the Eligible Employee's package of incentives and benefits in the aggregate; 
(iv) the relocation of the Eligible Employee's principal office by more than 
thirty (30) miles, unless approved by the Eligible Employee; (v) the material 
breach of this Plan or any other material agreement between the Eligible 
Employee and the Company regarding the terms and conditions of employment; or 
(vi) the failure of any acquiring or surviving corporation to assume the 
responsibilities of the Company under this Plan or under any other material 
agreement between the Eligible Employee and the Company regarding the terms 
and conditions of employment. 

     9.9  "NOTICE OF TERMINATION" has the meaning set forth in Section 3.6.

     9.10 "OPTION PLANS" shall mean those Plans adopted by the Company by 
which an Executive Officer has been or may be granted a stock option to 
acquire the Company's common stock or other equity securities, as well as any 
employee stock option plan adopted subsequent to the date hereof and prior to 
a Change of Control (and any plans succeeding thereto).

     9.11 "PARTICIPANT" has the meaning set forth in Section 2.1.

     9.12 "PERSON" shall mean any individual, firm, corporation or other 
entity, and shall include any successor (by merger or otherwise) of such 
entity.

     9.13 "PLAN" has the meaning set forth in Article 1.

     9.14 "SEVERANCE BENEFITS" has the meaning set forth in Section 3.1.

     9.15 "SEVERANCE PAYMENT" shall mean the Participant's base pay 
(excluding overtime, bonuses, draws, commissions, and other forms of 
additional compensation), at the rate in effect during the last regularly 
scheduled payroll period immediately preceding the Date of Termination.

     9.16 "TARGET BONUS" shall mean the greater of: (i) the Participant's 
target bonus for the year in which the Date of Termination occurs, as 
approved by the Compensation Committee of the Board of Directors or (ii) the 
average of the annual bonuses actually paid to the Participant over the two 
years immediately preceding the Date of Termination (or if less, the period 
of time the Participant has provided services to the Company).
                                          
                            ARTICLE 10 -- MISCELLANEOUS

     10.1 SEVERABILITY.  If any term, provision, covenant or restriction of 
the Plan is held by a court of competent jurisdiction or other authority to 
be invalid, void or unenforceable, the

                                       9.
<PAGE>

remainder of the terms, provisions, covenants and restrictions of the Plan 
shall remain in full force and effect and shall in no way be affected, 
impaired or invalidated.

     10.2 CONSTRUCTION OF PLAN.  Any gender, where appearing in the Plan, 
shall be deemed to include the other gender, the singular shall include the 
plural, and the plural shall include the singular, unless the context 
otherwise requires. Descriptive headings of the several Articles of the Plan 
are inserted for convenience only and shall not control or affect the meaning 
or construction of any of the provisions hereof.  In the event of a conflict 
between the text of the Plan and any summary, description or other 
information regarding the Plan, the text of the Plan shall control. 

     10.3 AMENDMENT OR TERMINATION. The Company, by resolution of the 
Company's Board of Directors or the Compensation Committee of the Board, may 
amend or terminate this Plan with respect to any Participant or all 
Participants at any time except during the Coverage Period.
                                          
                     ARTICLE 11 -- CLAIMS, INQUIRIES AND APPEALS

     11.1 APPLICATIONS FOR BENEFITS AND INQUIRIES.  Any application for 
benefits, inquiries about the Plan or inquiries about present or future 
rights under the Plan must be submitted to the Plan Administrator in writing. 
 The Plan Administrator is: 
                                          
                          Vice President, Human Resources
                                   CoCensys, Inc.
                                201 Technology Drive
                              Irvine, California 92618

     11.2 DENIAL OF CLAIMS.  In the event that any application for benefits 
is denied in whole or in part, the Plan Administrator must notify the 
applicant, in writing, of the denial of the application, and of the 
applicant's right to review the denial.  The written notice of denial will be 
set forth in a manner designed to be understood by the employee, and will 
include specific reasons for the denial, specific references to the Plan 
provision upon which the denial is based, a description of any additional 
material or information necessary for the applicant to perfect the claim 
along with an explanation as to why such information is necessary and an 
explanation of the Plan's claim procedure.

     This written notice will be given to the employee within 90 days after 
the Plan Administrator receives the application, unless special circumstances 
require an extension of time, in which case, the Plan Administrator has up to 
an additional 90 days for processing the application.  If an extension of 
time for processing is required, written notice of the extension will be 
furnished to the applicant before the end of the initial 90-day period.

     This notice of extension will describe the special circumstances 
necessitating the additional time and the date by which the Plan 
Administrator is to render its decision on the application.  If written 
notice of denial of the application for benefits is not furnished within the 

                                       10.
<PAGE>

specified time, the application shall be deemed to be denied.  The applicant 
will then be permitted to appeal the denial in accordance with the Review 
Procedure described below.

     11.3 REQUEST FOR A REVIEW.  Any person (or that person's authorized 
representative) for whom an application for benefits is denied (or deemed 
denied), in whole or in part, may appeal the denial by submitting a written 
request for a review to the Plan Administrator within 60 days after the 
application is denied (or deemed denied).  The Plan Administrator will give 
the applicant (or his or her representative) an opportunity to review 
pertinent documents in preparing a request for a review.  A request for a 
review shall be in writing and shall be addressed to:  
                                          
                          Vice President, Human Resources
                                   CoCensys, Inc.
                                201 Technology Drive
                              Irvine, California 92618

A request for review must set forth all of the grounds on which it is based, 
all facts in support of the request and any other matters that the applicant 
feels are pertinent.  The Plan Administrator may require the applicant to 
submit additional facts, documents or other material as it may find necessary 
or appropriate in making its review.

     11.4 DECISION ON REVIEW.  The Plan Administrator will act on each 
request for review within 60 days after receipt of the request, unless 
special circumstances require an extension of time (not to exceed an 
additional 60 days), for processing the request for a review.  If an 
extension for review is required, written notice of the extension will be 
furnished to the applicant within the initial 60-day period.  The Plan 
Administrator will give prompt, written notice of its decision to the 
applicant.  In the event that the Plan Administrator confirms the denial of 
the application for benefits in whole or in part, the notice will outline, in 
a manner calculated to be understood by the applicant, the specific reasons 
for the decision and the specific Plan provisions upon which the decision is 
based.  If written notice of the Plan Administrator's decision is not given 
to the applicant within the time prescribed in this Section 11.4, the 
application will be deemed denied on review.

     11.5 RULES AND PROCEDURES.  The Plan Administrator will establish rules 
and procedures, consistent with the Plan and with ERISA, as necessary and 
appropriate in carrying out its responsibilities in reviewing benefit claims. 
The Plan Administrator may require an applicant who wishes to submit 
additional information in connection with an appeal from the denial (or 
deemed denial) of benefits to do so at the applicant's own expense.

     11.6 EXHAUSTION OF REMEDIES.  No legal action for benefits under the 
Plan may be brought until the claimant has (i) submitted a written 
application for benefits in accordance with the procedures described by 
Section 11.1 above, (ii) been notified by the Plan Administrator that the 
application is denied (or the application is deemed denied due to the Plan 
Administrator's failure to act on it within the established time period), 
(iii) filed a written request for a review of the application in accordance 
with the appeal procedure described in Section 11.3 above and (iv) been 
notified in writing that the Plan Administrator has denied the appeal (or the 
appeal is

                                       11.
<PAGE>

deemed to be denied due to the Plan Administrator's failure to take any 
action on the claim within the time prescribed by Section 11.4 above). 
                                          
                        ARTICLE 12 -- OTHER PLAN INFORMATION

     12.1 EMPLOYER AND PLAN IDENTIFICATION NUMBERS.  The Employer 
Identification Number assigned to the Company (which is the "Plan Sponsor" as 
that term is used in ERISA) by the Internal Revenue Service is 330538836.  
The Plan Number assigned to the Plan by the Plan Sponsor pursuant to the 
instructions of the Internal Revenue Service is 504.

     12.2 ENDING DATE FOR PLAN'S FISCAL YEAR.  The date of the end of the 
fiscal year for the purpose of maintaining the Plan's records is December 31.

     12.3  AGENT FOR THE SERVICE OF LEGAL PROCESS.  The agent for the service 
of legal process with respect to the Plan is the General Counsel, CoCensys, 
Inc., 201 Technology Drive, Irvine, California 92618.

     12.4 PLAN SPONSOR AND ADMINISTRATOR.  The "Plan Sponsor" of the Plan is 
CoCensys, Inc., 201 Technology Drive, Irvine, California 92618. The "Plan 
Administrator" of the Plan is the Vice President, Human Resources, CoCensys, 
Inc., 201 Technology Drive, Irvine, California 92618.  The Plan Sponsor and 
Plan Administrator's telephone number is (949) 753-6100.  The Plan 
Administrator is the named fiduciary charged with the responsibility for 
administering the Plan. 
                                          
                       ARTICLE 13 -- STATEMENT OF ERISA RIGHTS

     13.1 Participants in this Plan (which is a welfare benefit plan 
sponsored by CoCensys, Inc.) are entitled to certain rights and protections 
under ERISA.  If you are a Participant, you are considered a participant in 
the Plan and, under ERISA, you are entitled to:

          (a)  Examine, without charge, at the Plan Administrator's office 
and at other specified locations, such as work sites, all Plan documents and 
copies of all documents filed by the Plan with the U.S. Department of Labor, 
such as detailed annual reports;

          (b)  Obtain copies of all Plan documents and Plan information upon 
written request to the Plan Administrator.  The Administrator may make a 
reasonable charge for the copies;

          (c)  Receive a summary of the Plan's annual financial report, in 
the case of a plan that is required to file an annual financial report with 
the Department of Labor.  (Generally, all pension plans and welfare plans 
with 100 or more participants must file these annual reports.)  

          (d)  In addition to creating rights for Plan participants, ERISA 
imposes duties upon the people responsible for the operation of the employee 
benefit plan. The people who operate the Plan, called "fiduciaries" of the 
Plan, have a duty to do so prudently and in the interest of you and other 
Plan participants and beneficiaries.

                                       12.
<PAGE>

          (e)  No one, including your employer or any other person, may fire 
you or otherwise discriminate against you in any way to prevent you from 
obtaining a Plan benefit or exercising your rights under ERISA.  If your 
claim for a Plan benefit is denied in whole or in part, you must receive a 
written explanation of the reason for the denial.  You have the right to have 
the Plan review and reconsider your claim.

          (f)  Under ERISA, there are steps you can take to enforce the above 
rights.  For instance, if you request materials from the Plan and do not 
receive them within 30 days, you may file suit in a federal court.  In such a 
case, the court may require the Plan Administrator to provide the materials 
and pay you up to $100 a day until you receive the materials, unless the 
materials were not sent because of reasons beyond the control of the Plan 
Administrator.  If you have a claim for benefits that is denied or ignored, 
in whole or in part, you may file suit in a state or federal court.  If it 
should happen that the Plan fiduciaries misuse the Plan's money or if you are 
discriminated against for asserting your rights, you may seek assistance from 
the U.S. Department of Labor, or you may file suit in a federal court.  The 
court will decide who should pay court costs and legal fees.  If you are 
successful, the court may order the person you have sued to pay these costs 
and fees.  If you lose, the court may order you to pay these costs and fees, 
for example, if it finds your claim is frivolous.

     13.2 If you have any questions about the Plan, you should contact the 
Plan Administrator.  If you have any questions about your rights under ERISA, 
you should contact the nearest area office of the U.S. Labor - Management 
Services Administration, Department of Labor. 
                                          
                               ARTICLE 14 -- EXECUTION

     Having been adopted by its Board on December 16, 1997, the Plan has been
executed by a duly authorized officer on May 13th, 1998.
 
                                  COCENSYS, INC.

                                  By:   F. Richard Nichol, Ph.D.               
                                     -------------------------------------------
                                  Title:   President and Chief Executive Officer
                                        ----------------------------------------

                                       13.