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                                                                    Exhibit 10.1


                                 LOAN AGREEMENT



This agreement dated June 28, 2000, is by and between 4-D Neuroimaging, a
California corporation based in San Diego, CA (the "Borrower"), and BDN, a
company based in Madrid, Spain (the "Lender"), (each the "Party" and together
the "Parties").

WHEREAS, the Borrower has the necessity to borrow funds from the Lender for
working capital purposes, and

WHEREAS, the Lender is able to and agrees to provide funds for the purpose
intended, and

NOW, THEREFORE, Lender hereby agrees to provide to Borrower a loan for working
capital purposes. This loan is made available to the Borrower by the Lender
based on the following terms, conditions and procedures:

FORM OF LOAN:                       This loan takes the form of a Promissory
                                    Note, which accrues simple interest and can
                                    be repaid in part or in whole at any time.

TERM, DURATION:                     This loan shall be made available to
                                    Borrower for a period beginning the date
                                    indicated above, and ending on September 30,
                                    2000. All amounts owed shall become due and
                                    payable on this date, unless otherwise
                                    amended in writing by mutual agreement.

ACKNOWLEDGEMENT:                    The loan is authenticated by the signing of
                                    this document below, by duly authorized
                                    representatives of the respective Parties.

AMOUNT, PURPOSE AND                 The amount of this loan is $350,000 and is
FUNDS TRANSFER:                     to be used for 4-D Neuroimaging working
                                    capital purposes.

                                    Funds shall transfer from the Lender to the
                                    Borrower and be sent by interbank wire
                                    transfer to the following back account:

                                              Silicon Valley Bank
                                              San Diego, CA
                                              ABA #121140399
                                              FBO: 4-D Neuroimaging
                                              A/C #3300145899
                                              Swift #SVBKUS6SA


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Loan Agreement                                                            Page 2


INTEREST RATE AND                   The starting interest rate shall be based on
PAYMENT:                            the three month U.S. dollar LIBOR + 1%,
                                    rounded up to the nearest quarter percent.
                                    The U.S. dollar LIBOR rate shall be
                                    determined by referring to the quoted rate
                                    in the Wall Street Journal printed on the
                                    date indicated above, representing the prior
                                    day's three month rate. The starting rate
                                    shall continue effective until September 30,
                                    2000.

INTEREST ACCRUAL:                   Interest shall accrue during the period and
                                    shall not compound, commencing with the day
                                    of receipt of the funds. Interest shall be
                                    calculated daily and accrued monthly if not
                                    paid. At the end of the period all principal
                                    and interest shall become due and payable.
                                    If interest is not paid then compounding
                                    will commence.

CURRENCY EXCHANGE:                  Borrower shall be held responsible for
                                    paying the interest and repaying the
                                    principal in the Lender's currency.

REPAYMENT:                          The Borrower can repay in part or in whole
                                    all outstanding amounts owed, including
                                    interest, at any time, all interest due
                                    being paid first, then principal, without
                                    penalty, to the bank indicated by Lender.

PLEDGES:                            Tangible assets such as receivables or fixed
                                    assets may be pledged as security for the
                                    loan upon mutual agreement, but are not a
                                    necessary precondition for funds to be drawn
                                    down.

ASSIGNABILITY:                      The Lender retains the right to assign this
                                    Loan Agreement to any party without
                                    modification, or if modifications are
                                    required, by receiving in advance the
                                    written consent of the Borrower.

This Loan Agreement has been executed by the Persons below as of the date
indicated above, each Person being the duly appointed representative.




/s/ Felipe Fernandez                       /s/ D. Scott Buchanan
-----------------------------------        -------------------------------------
Mr. Felipe Fernandez                       Dr. D. Scott Buchanan
BDN Spain                                  4-D Neuroimaging
Lender                                     Borrower