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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2020-03-11T22:52:00.8443268+00:00 -->
<!-- Version            : 5.0.1.369 -->
<!-- Package ID         : 2df9090719844842aa12376c5ae9230e -->
<!-- Copyright (c) 2020 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="hsdt_HealthTechConnexIncorporationMember" name="HealthTechConnexIncorporationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_HeuroCanadaIncorporationMember" name="HeuroCanadaIncorporationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ComputerSoftwareAndHardwareMember" name="ComputerSoftwareAndHardwareMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_SharePurchaseAgreementMember" name="SharePurchaseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_CoPromotionAgreementMember" name="CoPromotionAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_PonsMember" name="PonsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ProprietaryTechnologyMember" name="ProprietaryTechnologyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ClinicalResearchAndCoPromotionAgreementMember" name="ClinicalResearchAndCoPromotionAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_EmployeeAndNonEmployeeStockOptionMember" name="EmployeeAndNonEmployeeStockOptionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NeurocatchDeviceMember" name="NeurocatchDeviceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ServicesPerformedUsingNeurocatchDeviceMember" name="ServicesPerformedUsingNeurocatchDeviceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_PotentialAmountReceivable" name="PotentialAmountReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_NumberOfDevices" name="NumberOfDevices" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOtherReceivables" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOtherReceivables" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_BusinessAcquisitionPurchasePriceAllocationGoodwillNotExpectedTaxDeductibleAmount" name="BusinessAcquisitionPurchasePriceAllocationGoodwillNotExpectedTaxDeductibleAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_NumberOfPatientsToCollectData" name="NumberOfPatientsToCollectData" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_InitialTermOfExclusiveRight" name="InitialTermOfExclusiveRight" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_AdditionalRenewalTermOfExclusiveRight" name="AdditionalRenewalTermOfExclusiveRight" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_WrittenNoticePeriodForAdditionalRenewalTerm" name="WrittenNoticePeriodForAdditionalRenewalTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_LicenseRevenueTermOfAgreement" name="LicenseRevenueTermOfAgreement" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_AcquiredProprietarySoftwareMember" name="AcquiredProprietarySoftwareMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NumberOfOperatingLease" name="NumberOfOperatingLease" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OperatingLeaseRightOfUseAssetAmortization" name="OperatingLeaseRightOfUseAssetAmortization" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ReclassificationToAdditionalPaidInCapitalUponModificationOfStockOptions" name="ReclassificationToAdditionalPaidInCapitalUponModificationOfStockOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ReclassificationOfStockBasedCompensationLiabilityClassifiedStockOptions" name="ReclassificationOfStockBasedCompensationLiabilityClassifiedStockOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ContractWithCustomerPerformanceObligationAndPayment" name="ContractWithCustomerPerformanceObligationAndPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ContractWithCustomerPerformanceObligationAndPaymentDueInOneYear" name="ContractWithCustomerPerformanceObligationAndPaymentDueInOneYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ContractWithCustomerPerformanceObligationAndPaymentDueInTwoYears" name="ContractWithCustomerPerformanceObligationAndPaymentDueInTwoYears" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ContractWithCustomerPerformanceObligationAndPaymentDueInThreeYears" name="ContractWithCustomerPerformanceObligationAndPaymentDueInThreeYears" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_CostOfGoodsSoldPerDevice" name="CostOfGoodsSoldPerDevice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_NumberOfFranchiseAgreements" name="NumberOfFranchiseAgreements" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_PercentageOfFranchiseFeeRevenue" name="PercentageOfFranchiseFeeRevenue" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_AccountsReceivableNetCurrentFromContracts" name="AccountsReceivableNetCurrentFromContracts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_BlackScholesModelMember" name="BlackScholesModelMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NonCurrentReceivableMember" name="NonCurrentReceivableMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ScheduleOfStockholdersEquityLineItems" name="ScheduleOfStockholdersEquityLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ScheduleOfStockholdersEquityTable" name="ScheduleOfStockholdersEquityTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_WarrantsFourMember" name="WarrantsFourMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_AprilTwoThousandSixteenOfferingandMayTwoThousandSixteenOverAllotmentMember" name="AprilTwoThousandSixteenOfferingandMayTwoThousandSixteenOverAllotmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_WarrantsSevenMember" name="WarrantsSevenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_PublicOfferingMember" name="PublicOfferingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_TrancheOneMember" name="TrancheOneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_TrancheTwoMember" name="TrancheTwoMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_TrancheThreeMember" name="TrancheThreeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NovemberTwoThousandAndEighteenPublicOfferingMember" name="NovemberTwoThousandAndEighteenPublicOfferingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NovemberTwoThousandAndNineteenPublicOfferingMember" name="NovemberTwoThousandAndNineteenPublicOfferingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ClassOfWarrantsOrRightExpirationDate" name="ClassOfWarrantsOrRightExpirationDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OptionsExercisableToPurchaseUnits" name="OptionsExercisableToPurchaseUnits" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OptionsExercisePricePerUnit" name="OptionsExercisePricePerUnit" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OfferingExpirationPeriod" name="OfferingExpirationPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OtherCashIssuanceCostsRelatedToOffering" name="OtherCashIssuanceCostsRelatedToOffering" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightExercised" name="ClassOfWarrantOrRightExercised" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightCancelledDueToExpiration" name="ClassOfWarrantOrRightCancelledDueToExpiration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_GrossProceedsFromIssuanceOrSaleOfEquity" name="GrossProceedsFromIssuanceOrSaleOfEquity" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_WarrantsExpirationDate" name="WarrantsExpirationDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_DecreaseInAdditionalPaidInCapital" name="DecreaseInAdditionalPaidInCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_WarrantsGrantedMember" name="WarrantsGrantedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NumberOfTranches" name="NumberOfTranches" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_FairValueOfWarrantsReclassifiedToAdditionalPaidInCapital" name="FairValueOfWarrantsReclassifiedToAdditionalPaidInCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_PaymentsForUnderwritingDiscountsAndCommissions" name="PaymentsForUnderwritingDiscountsAndCommissions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_PaymentsForOfferingExpenses" name="PaymentsForOfferingExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ProceedsFromIssuanceOfCommonStockNet" name="ProceedsFromIssuanceOfCommonStockNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_FairValueOfWarrantsAtIssuance" name="FairValueOfWarrantsAtIssuance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ExpenseRelatedToDistributionOfCommonStockAndWarrants" name="ExpenseRelatedToDistributionOfCommonStockAndWarrants" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_AccruedShareIssuanceCost" name="AccruedShareIssuanceCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_FairValueOfWarrantsLiability" name="FairValueOfWarrantsLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_FairValueOfWarrantLiabilityAtIssuance" name="FairValueOfWarrantLiabilityAtIssuance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_FairValueOfWarrantsLiabilityExercise" name="FairValueOfWarrantsLiabilityExercise" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_FairValueOfPreviouslyEquityClassifiedWarrants" name="FairValueOfPreviouslyEquityClassifiedWarrants" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_FairValueOfPreviouslyLiabilityClassifiedWarrantsReclassifiedToAdditionalPaidInCapital" name="FairValueOfPreviouslyLiabilityClassifiedWarrantsReclassifiedToAdditionalPaidInCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightGranted" name="ClassOfWarrantOrRightGranted" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightExpired" name="ClassOfWarrantOrRightExpired" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightOutstandingAndExercisable" name="ClassOfWarrantOrRightOutstandingAndExercisable" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightExercisePriceGrantedOfWarrantsOrRights" name="ClassOfWarrantOrRightExercisePriceGrantedOfWarrantsOrRights" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightExercisePriceExpiredOfWarrantsOrRights" name="ClassOfWarrantOrRightExercisePriceExpiredOfWarrantsOrRights" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightExercisePriceExercisedOfWarrantsOrRights" name="ClassOfWarrantOrRightExercisePriceExercisedOfWarrantsOrRights" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ClassOfWarrantOrRightExercisePriceOutstandingAndExercisableOfWarrantsOrRights" name="ClassOfWarrantOrRightExercisePriceOutstandingAndExercisableOfWarrantsOrRights" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_WarrantsOneMember" name="WarrantsOneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_WarrantsThreeMember" name="WarrantsThreeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_WarrantsFiveMember" name="WarrantsFiveMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_WarrantsEightMember" name="WarrantsEightMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_WarrantsNineMember" name="WarrantsNineMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_CommonStockCapitalSharesReservedForFutureIssuanceNewShares" name="CommonStockCapitalSharesReservedForFutureIssuanceNewShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_TwoThousandEighteenOmnibusIncentivePlanMember" name="TwoThousandEighteenOmnibusIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_TwoThousandSixteenOmnibusIncentivePlanMember" name="TwoThousandSixteenOmnibusIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_StockIssuedDuringPeriodSharesStockOptionsExercisedOnCashlessBasis" name="StockIssuedDuringPeriodSharesStockOptionsExercisedOnCashlessBasis" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_NumberOfCommonStockSharesWithheld" name="NumberOfCommonStockSharesWithheld" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_SharebasedCompensationArrangementByReductionToStockbasedCompensationLiability" name="SharebasedCompensationArrangementByReductionToStockbasedCompensationLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_SharebasedCompensationArrangementByStockbasedCompensationLiabilityReclassificationToAdditionalPaidInCapitalUponModificationOfStockOptions" name="SharebasedCompensationArrangementByStockbasedCompensationLiabilityReclassificationToAdditionalPaidInCapitalUponModificationOfStockOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPostModificationPeriodWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPostModificationPeriodWeightedAverageGrantDateFairValue" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OptionOneMember" name="OptionOneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwoMember" name="OptionTwoMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionThreeMember" name="OptionThreeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionFourMember" name="OptionFourMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionFiveMember" name="OptionFiveMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionSixMember" name="OptionSixMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionSevenMember" name="OptionSevenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionEightMember" name="OptionEightMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionNineMember" name="OptionNineMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTenMember" name="OptionTenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionElevenMember" name="OptionElevenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwelveMember" name="OptionTwelveMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionThirteenMember" name="OptionThirteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionFourteenMember" name="OptionFourteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionFifteenMember" name="OptionFifteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionSixteenMember" name="OptionSixteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionsSeventeenMember" name="OptionsSeventeenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionEighteenMember" name="OptionEighteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionNineteenMember" name="OptionNineteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyMember" name="OptionTwentyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyOneMember" name="OptionTwentyOneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyTwoMember" name="OptionTwentyTwoMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyThreeMember" name="OptionTwentyThreeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyFourMember" name="OptionTwentyFourMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyFiveMember" name="OptionTwentyFiveMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentySixMember" name="OptionTwentySixMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentySevenMember" name="OptionTwentySevenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyEightMember" name="OptionTwentyEightMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_OptionTwentyNineMember" name="OptionTwentyNineMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodExercised" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodExercised" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodCancelled" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodCancelled" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodForeignExchangeGains" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodForeignExchangeGains" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInNonEmployeeChangeInFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInNonEmployeeChangeInFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodReclassificationToAdditionalPaidInCapital" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodReclassificationToAdditionalPaidInCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_NumberOfRestrictedStockUnitsWithheldForTaxes" name="NumberOfRestrictedStockUnitsWithheldForTaxes" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_AccruedFranchiseFeeCurrent" name="AccruedFranchiseFeeCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_IncomeTaxReconciliationExpectedIncomeTaxRecovery" name="IncomeTaxReconciliationExpectedIncomeTaxRecovery" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_IncomeTaxReconciliationChangeInDerivativeLiability" name="IncomeTaxReconciliationChangeInDerivativeLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_IncomeTaxReconciliationNondeductibleExpenseChangeInOtherPermanentDifference" name="IncomeTaxReconciliationNondeductibleExpenseChangeInOtherPermanentDifference" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_OperatingLossCarryforwardsExpirationYear" name="OperatingLossCarryforwardsExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_IncomeTaxesLineItems" name="IncomeTaxesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_IncomeTaxesTable" name="IncomeTaxesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_PercentageOfRoyaltyOnNetRevenue" name="PercentageOfRoyaltyOnNetRevenue" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_CommitmentsAndContingenciesLineItems" name="CommitmentsAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_CommitmentsAndContingenciesTable" name="CommitmentsAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_AdvancedNeuroRehabilitationLimitedLiabilityCompanyMember" name="AdvancedNeuroRehabilitationLimitedLiabilityCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_LicenseAgreementForExclusiveRightsOnPatentPendingTechnologyMember" name="LicenseAgreementForExclusiveRightsOnPatentPendingTechnologyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_AAndBCompanyLimitedMember" name="AAndBCompanyLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_AssetPurchaseAgreementMember" name="AssetPurchaseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_AltairLimitedLiabilityCompanyMember" name="AltairLimitedLiabilityCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ManufacturingAndSupplyAgreementMember" name="ManufacturingAndSupplyAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_KeyTronicCorporationMember" name="KeyTronicCorporationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_PenaltyPayable" name="PenaltyPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_PercentageOfRoyaltyOnSales" name="PercentageOfRoyaltyOnSales" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_EffectiveDateOfTerminationOfAgreement" name="EffectiveDateOfTerminationOfAgreement" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OperatingLeaseCommencementDate" name="OperatingLeaseCommencementDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OperatingLeaseOptionToExtendLeaseTermYear" name="OperatingLeaseOptionToExtendLeaseTermYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OperatingLeaseOptionToExtendLeaseTermDate" name="OperatingLeaseOptionToExtendLeaseTermDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OperatingLeaseRentPlusUtilitiesBeginningDate" name="OperatingLeaseRentPlusUtilitiesBeginningDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_OperatingLeaseAnnualIncreaseInRentalPercentage" name="OperatingLeaseAnnualIncreaseInRentalPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="hsdt_LongTermPurchaseCommitmentAutoRenewalPeriod" name="LongTermPurchaseCommitmentAutoRenewalPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_LongTermPurchaseCommitmentNoticePeriodToCancelRenewalPeriod" name="LongTermPurchaseCommitmentNoticePeriodToCancelRenewalPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_NumberOfFoundingClinics" name="NumberOfFoundingClinics" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_MaximumAmountOfLongTermPurchaseCommitment" name="MaximumAmountOfLongTermPurchaseCommitment" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_NetProftAndLossBasis" name="NetProftAndLossBasis" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_PartialConsiderationGrantedPeriod" name="PartialConsiderationGrantedPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_NumberOfAdditionalClinics" name="NumberOfAdditionalClinics" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_NumberOfClinicsAuthorized" name="NumberOfClinicsAuthorized" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ConsultingFeePayableToDirectors" name="ConsultingFeePayableToDirectors" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="hsdt_MontelMediaIncMember" name="MontelMediaIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ConsultingAgreementMember" name="ConsultingAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_NonEmployeeStockOptionMember" name="NonEmployeeStockOptionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ClinvueLLCMember" name="ClinvueLLCMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_PercentageOfBeneficiallyOwnedCommonStock" name="PercentageOfBeneficiallyOwnedCommonStock" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ReimbursableTrialCost" name="ReimbursableTrialCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="hsdt_ExpirationDateOfOriginalContract" name="ExpirationDateOfOriginalContract" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ScheduleOfCostSharingAgreementAndCooperativeResearchAndDevelopmentAgreementLineItems" name="ScheduleOfCostSharingAgreementAndCooperativeResearchAndDevelopmentAgreementLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ScheduleOfCostSharingAgreementAndCooperativeResearchAndDevelopmentAgreementTable" name="ScheduleOfCostSharingAgreementAndCooperativeResearchAndDevelopmentAgreementTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_UnitedStatesArmyMedicalResearchAndMaterielCommandMember" name="UnitedStatesArmyMedicalResearchAndMaterielCommandMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_CooperativeResearchAndDevelopmentAgreementMember" name="CooperativeResearchAndDevelopmentAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="hsdt_ExpirationYearOfOriginalContract" name="ExpirationYearOfOriginalContract" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ExtendedExpirationDateOfOriginalContract" name="ExtendedExpirationDateOfOriginalContract" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="hsdt_ReceiptOfExpenseReimbursement" name="ReceiptOfExpenseReimbursement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
</xsd:schema>
