Contains research objectives and reports on six research projects.U.S. Public Health Service (B-3055)U.S. Public Health Service (B-3090)Office of Naval Research (Nonr-1841 (70))Air Force (AF33(616)-7588)Air Force (AFAFOSR-155-63)Air Force (AFAFOSR-155-63)Army Chemical Corps (DA-18-108-405-Cml-942)National Science Foundation (Grant G-16526

Cogan, D. G.

Finnila, C. A.

Gottlieb, G. L.

Henrikson, W. G.

Howland, H. R.

Kurkjian, R. G.

Labaugh, K. D.

Northrop, G. H.

Sandberg, A. A.

Segal, G.

Sever, G.

Smith, Gabriella W.

Stanten, S. F.

Stark, J. W.

Stark, L.

Tunstall, B. P.

Van Horn, E. C., Jr.

Young, L. R.

Zapol, W. M.

Zuber, B. L.

DSpace@MIT

XXV. NEUROLOGYL. Stark A. A. Sandberg I. H. ThomaeF. H. Baker Susanne Shuman A. TroelstraR. W. Cornew J. L. Simpson E. C. Van Horn, Jr.H. T. Hermann Gabriella W. Smith P. A. WillisJ. C. Houk, Jr. I. Sobel S. YasuiE. L. Mudamra S. F. Stanten L. R. YoungF. Naves B. L. ZuberRESEARCH OBJECTIVESThe aim of our work is to apply the concept of communication and control theoryto our analyses of neurological and biological mechanisms. The group is composed ofneurologists, mathematicians, and electrical engineers. Our research endeavors tospan a wide field that includes experiments on human control mechanisms, mathemat-ical methods for analysis of nonlinear systems, including simulation, clinical studieswith on-line digital-computer techniques employed, neurophsiology of simple inverte-brate receptors, and adaptive pattern-recognition techniques with the use of computers.L. StarkA. WORK COMPLETEDShort summaries follow of theses accepted by the departments, and in partial fulfill-ment of the requirements for the degrees, indicated.1. A Sampled Data Model for Eye-Tracking Movements, Sc.D. Thesis, Departmentof Aeronautics and Astronautics, M.I.T., May 1962.A sampled-data model has been developed, based on the following principles: 1) thepredictability of the target signal has a profound effect on the system's ability of trackcontinuous and discontinuous target motion; 2) the saccadic and pursuit systems functionseparately; and 3) the eye-movement tracking characteristics are of a discrete nature.L. R. Young2. A Convenient Eye Position and Pupil Size Meter, S.M.Thesis, Department ofElectrical Engineering, M.I.T., June 1962.A specialized television system, in which a technique of circular track scanning isemployed, takes continuous readings of eye pupil size and position. The ac componentsof scanning deflection signals are proportional to the eye pupil diameter, and the dccomponents are proportional to the coordinates of eye pupil position.C. A. FinnilaThis research is supported in part by the U.S. Public Health Service (B-3055,B-3090), the Office of Naval Research (Nonr-1841 (70)), the Air Force (AF33(616)-7588,AF49(638)-1130, AFAFOSR-155-63), and the Army Chemical Corps (DA-18-108-405-Cml-942); and in part by the National Science Foundation (Grant G-16526).QPR No. 68 229(XXV. NEUROLOGY)3. The Design and Construction of a Motor Coordination Testing Servomechanism,Department of Electrical Engineering, M.I.T., June 1962.An instrument consisting of two electrically identical dc servomechanisms with con-centric output shafts was designed to test the dynamic behavior of human motor coordi-nation in the lower arm and wrist.G. L. Gottlieb4. Effects of Alcohol and Barbiturates on Rotational Mechanical Responses, S. B.Thesis, Department of Electrical Engineering, M.I.T., June 1962.The effect of alcohol and barbiturates on the response of subjects following a lightspot with a pointer was found to depend on the frequency at which the input light movedon the screen.W. G. Henrikson5. Head-Position Indicator, S.B. Thesis, Department of Electrical Engineering,M.I.T., June 1962.A gyroscope-demodular system was used to indicate head position, so that the placewhere a subject looks in a given situation can be determined.H. R. Howland6. Computer Analysis of Handwriting Applied to Cancer Detection, S.B. Thesis,Department of Electrical Engineering, M.I.T., June 1962.The Kaufer Neuromuscular Test was programmed on the TX-0 computer, the resultsanalyzed, and improvements suggested.R. G. Kurkjian7. A Semiconductor Regulated DC Power Supply, S.B.Thesis, Department of Elec-trical Engineering, M.I.T., June 1962.An efficient power supply for application to a servomechanism system is obtained bycascading a transistorized filter and a transistor dc regulator.K. D. Labaugh8. A Measuring Device for the Tremor of the Human Finger, S.B. Thesis, Depart-ment of Electrical Engineering, M.I.T., June 1962.With a transducer that employs the change in capacitance of two plates, caused byvarying the distance between them, a signal can be detected which indicates fingertremor.G. SegalQPR No. 68 230(XXV. NEUROLOGY)9. The Pupil Light Reflex in the Owl, S.B. Thesis, Department of Biology, M.I.T.,May 1962.The pupil reflex of an owl to light was found to contain nonlinearities that contributeto the variability of the gain results.G. H. Northrop10. Linear Light Source for Eye Stimulation, Department of Electrical Engineering,M.I.T., June 1962.A television screen is used as a light source to stimulate the eye, and thus enableone to observe the pupil under various stimulation conditions.G. Sever11. The Effects of Drugs on the Transfer Function of the Human Pupil System,Department of Biology, M.I.T., May 1962.Using physostignine and hydroxyamphetamine hydrobromide together, we foundthat the minimum phase lag was increased, and the gain of the transfer func-tion decreased.J. W. Stark12. Effect of Operating Conditions on Noise in Human Pupil Servomechanism, S.B.Thesis, Department of Electrical Engineering, M.I.T., June 1962.The mean-square value of noise was found to be a monotonically increasing functionof light intensity: the noise has stationary components from 0.08 cps to 2 cps, and thespectrum contained a relative maximum at 15 cycles per minute which corresponded tothe respiration rate.B. P. Tunstall13. Transient Adaptation in the Human Pupil Servomechanism, S.B. Thesis, Depart-ment of Biology, M.I.T., June 1962.The rapid rise in visual threshold is concomitant, but not simultaneous, with arapid rise in pupil response when the steady light input to the pupil is decreased.W. M. ZapolQPR No. 68 231(XXV. NEUROLOGY)B. EYE CONVERGENCEAn apparatus similar to that described by Rashbass and Westheimerl (Fig. XXV-1)has been used to present a convergence-divergence stimulus to human subjects.GLASSESO MAXIMUM CENTERCONVERGENCE LINE co = 150CMIOCM FROM 0 FROM 0/ PLANE/ MIRRORFACE OF CATHODE-RAY TUBEFig. XXV-1. Eye-convergence apparatus.The electrical apparatus used is shown in Fig. XXV-2. Eye movements arerecorded from photocells mounted on eyeglass frames.2 The variable measuredEYE BRIDGE VOLTAGE AMPLIFIERGLASSES IRCUIT FOR FOLLOWER XIOBALANCINGFig. XXV-2. Electrical circuit for eye-convergenceapparatus.thus far, the angle of convergence-divergence (ar), is defined as the angle betweenthe line of sight when the eye is focused at infinity and the line passing throughthe target and the center of the eye. Calibration of eye movements (Fig. XXV-3)is accomplished by having the subject focus on a light appearing at infinity andthen on a light that is a known distance from the first. Thus a known a is sub-rtended. Subjects have been presented with sinusoidal and step stimuli. Recordsof stimuli and responses appear in Fig. XXV-3. Future investigations will includeclosed-loop predictable and unpredictable frequency responses with single andQPR No. 68 232(a) (C)ar =0 oar= 5.09"as = 6780as= 0Fig. XXV-3.a r  20 ° LEFTar = 00a,= 20aRIGHTb) (d)Step response, f = 1.0 cps.Sinusoidal response, f = 0.1 ps.Sinusoidal response, f = 1.0 cps.Typical calibration, a s = stimulus angle; arresponse angle (average value shown).QPR No. 68 233(XXV. NEUROLOGY)mixed computer-produced sinusoidal stimuli used. Finally, the dynamics of thesystem when the feedback loop has been opened will be investigated.B. L. Zuber, L. StarkReferences1. C. Rashbass and G. Westheimer, Disjunctive eye movements, J. Physiol. 159,339-360 (1961).2. G. P. Nelson, L. Stark, and L. R. Young, Phototube glasses for measuring eyemovements, Quarterly Progress Report No. 67, Research Laboratory of Electronics,M.I.T., October 15, 1962, pp. 214-216.C. PUPILLARY NOISEIn an attempt to discover possible sources of pupillary unrest (noise), a crosscorre-lation program has been written for the GE 225 computer. With the aid of this programPUPILAREAI i bHEMiRESPIRATIONSIGNALPUPILAREARESPIRATIONSIGNAL ti14~ii~~l~ iiiii lii iiri 14  i lM!! ii ii :::, I : l ii i::i j!7mli- I LtIt'V"t~- .855 SECFig. XXV-4. Digitalized records of pupil area and respiration signal.QPR No. 68II l ll :: ii i i~ i i i ii I :i i~ i i iii iiiii 'iiiiiiiii iil: i-iiii~ ii:ii -ljiiI . . . ... ... L.. ii== .., ,=liil =,=,,=Inili  iiiii ili  IIIIl II lI !iii il = =Ii! =IIlll ~ iiii, l= i il ilii =, =, =............................... =....... " i i=ii=.;i.I i i!!! i~i li il!!ill~il!! ... . . .. .... .. I !I I i i i ..41 l I II IU, ::'!!"::::': : :; ~ - ;: ~;: ~~ - ~::: ~ -~ ii: ~y~:I;::: : i._:: ::::: ~i::: :: ~ ':: - "'" ' : "'~'~"" "ii:::: :: ""~'~ ::: ::'::::::: ii:iiiii ''' iii-:i;:I:I: ::; ''riiiii: ~ lii!:iiiiiii!" ~iiiiiiiliiiiiiii ::': : :: :::" ' '~' "' :' :::': ::' ::~~ ~ ~:::I::::I::::i:I:,:: -:i: :::;::;: ::: ::!iliii'iliiiiliiiiiiiii'::'::i'-liiiiiiiiiiiiilliiiiiil'iliiil.~iiiiiiiiii- --- -IlW1Ji~!iiiii i234(XXV. NEUROLOGY)x0-- .4875 SECFig. XXV-5. Crosscorrelation between pupil noise and respiration.pupil noise can be compared with other biological signals to determine whether or notcorrelation exists.As a first attempt, the pupil noise was crosscorrelated with a respiration signal.This respiration signal was obtained from a device that consisted of a thermistor (FenwalType BC32L1) placed inside a hollow plastic tube, which, in turn, was inserted intothe nostril of the subject. As the subject inhaled and exhaled, the temperature in theenvironment of the thermistor changed and thus the resistance of the thermistor changed.The thermistor was used as one arm of a resistance bridge, and the signal obtainedindicated, in some sense, the respiration of the subject.The respiration was crosscorrelated with the pupil area under constant illuminationconditions. Three cases were tried: (a) slow breathing, (b) regular breathing, and(c) fast breathing.Figure XXV-4 shows a typical area and respiration signal for the slow-breathingcase after digitalization, and Fig. XXV-5 shows its crosscorrelation function. Thecrosscorrelation function is( (t) -- ) (y(t+T) -Y)R ( T ) a axyxyHere, the bar denotes time average, x is the pupil area, y is the respiration signal,T and 7 are the respective time-average values, and ax and o are the respective rmsQPR No. 68 235(XXV. NEUROLOGY)values of the signal. We see from Fig. XXV-5 that the correlation peak goes as highas 15 per cent. For regular breathing the correlation peak was approximately 11 percent, and for fast breathing a peak of approximately 2 per cent was obtained.No definite conclusions will be drawn now, due to the fact that the experiment wasperformed only once, and there is the possibility of head movement during breathing,which could add correlation.S. F. Stanten, L. StarkD. EYE-MOVEMENT EXPERIMENTATIONEquipment for our eye-movement experiment has been set up at the MassachusettsEye and Ear Infirmary of the Massachusetts General Hospital. It is very similar to theexperimental arrangement used for the study of the effect of pharmacological agents onIoTARGET ._ANGLE O0-10000-10.--i - I SEC5CM/SEC(a)TARGET 1000ANGLEANGLE -100BRUSH INSTRUMENTS DIVISION OFCLEVITECORPORATION CLEVEIANt-- k-ISEC5CM/SEC(b)Fig. XXV-6. Response to step changes in target angle recorded from (a) normalsubject, and (b) young child with possible brain tumor.QPR No. 68............IN i236(XXV. NEUROLOGY)control of eye movements.l We are studying patients with various eye-movement dis-orders who sit with head fixed in a "catcher's" mask. They wear a pair of photocellgoggles that measure eye movement as a moving spot of light on an oscilloscope screenis tracked.The patient performs a varied set of tasks: (a) directed gaze in darkness - lateraland forward; (b) compensatory movements to passive head rotation; (c) directed gazeat fixation point; and (d) conjugate eye movements following moving targets of steps,constant velocity, constant acceleration, and sinusoids. These are designed to measurecertain types of eye movements - saccades, pursuit, fixation, stability, and nystagmus.Figure XXV-6a shows the response of a normal subject to step changes in targetangle. Note the rapid response without much overshoot. Figure XXV-6b shows theresponse of a young child with a possible brain tumor. His record shows considerableoscillatory overshoot that was not seen in ordinary clinical examination.Gabriella W. Smith, D. G. Cogan, L. Stark(Dr. D. G. Cogan is Chief of Ophthalmology, Massachusetts Eye and Ear Infirmary.)References1. H. T. Hermann, G. P. Nelson, L. Stark, and L. R. Young, Effect of pharma-cological agents on control of eye movements, Quarterly Progress Report No. 67,Research Laboratory of Electronics, M.I.T., October 15, 1962, pp. 231-232.E. MODEL OF PUPIL REFLEX TO LIGHTWork continues in an attempt to refine our model of the human pupillary responseto light. Extensive use has been made of the GE 225 computer as an integral part of ahybrid analog-digital pupil model, and to obtain reliable results by the use of on-lineaveraging of experimental data.From Fig. XXV-7, and from previous work1, 2 it is apparent that some form of scalecompression is present early in the signal processing by the system. Figure XXV-8illustrates the existence of a nonlinearity with memory. Note the small effect of thepulsewidth on the height of the response.The model presented previously is shown in Fig. XXV-9. The revised model shownin Fig. XXV-10 differs from the previous model in the following respects.(i) A logarithmic scale-compression factor has been added, the results of which areshown in Fig. XXV-11.(ii) An extra and faster time constant has been added to the transfer function of T.This addition will aid in reducing the effect on response height of pulsewidths from10 msec to 2 seconds. However, this addition decreases the dependence of time to peakon the pulsewidth in contradiction with experimental results.QPR No. 68 2370.03OOLUS0.02_J-JS001O0Fig. XXV-7.6MM0.21MM7-6.25MM0.21MMLU_1-5.20MMTIMEPupil response to light pulses of different heights.- ISEC t-4.74 MM -STIMULITi = 1.00,0.50,0.10,0.05,0.01 SECITiI -= 0.006 MILLILUMENA I=0.016 MILLILUMEN0.02zLU0.01 :0__JTIME -Fig. XXV-8.QPR No. 68Average response of pupil to light pulses of decreasing width.238I "j/IOld pupil model. T1 = 1.5 sec; T = 0.15 sec; a = 0.1.'(t)I'(t) = LOG 2 [K I(t - T) + 1] K = 6, r1 = 1.5 SEC, r 2 = 0 . 2 , r = 0.2 SECa= 0.05, = 0.8, T= 0.2 SECFig. XXV- 10. New pupil model.5432I -I SEC--Fig. XXV-11. Response (top) of pupil model to positive pulses (bottom) of greatlyvarying amplitude. Note scale compression of log function. (Over-shoot of the simulated stimuli is due to X-Y recorder inertia. )QPR No. 68I (t)Fig. XXV-9.239(XXV. NEUROLOGY)(iii) The lower diodes have been introduced to make the recently introduced rapidlight adaptation ineffective during dark adaptation.A. A. Sandberg, L. StarkReferences1. L. Stark, Julia H. Redhead, and H. Van der Tweel, Pulse response of thepupil, Acta Physiol. Pharmacol. Neerl. (in press).2. F. H. Baker, Pupil response to short-duration pulses, Quarterly ProgressReport No. 65, Research Laboratory of Electronics, M.I.T., April 15, 1962, pp. 251-257.F. HUMAN PREDICTION OF FILTERED RANDOM SEQUENCESAn experiment has been designed to investigate a human subject's strategy in pre-dicting successive numbers in a nonindependent sequence of random numbers. Theexperiment is implemented in the form of a digital-computer program that interactswith the subject and the experimenter by means of typewriters. This program hasbeen written and checked out, and the first carefully controlled experiments are nowin progress.The subject is presented with a sequence of positive and negative decimal integers,which are formed by taking a weighted sum of (a) a number obtained by an independentsampling of a uniform distribution of zero mean and (b) a linear combination of previousnumbers in the output sequence.After each number is presented, the subject is asked to predict what the next numberin the sequence will be. It is apparent, and, indeed, can be proved, that he may mini-mize his mean-square error by setting his prediction just equal to the quantity (b) above.This is then his "optimum policy."Figure XXV-12 gives a block diagram of the experimental configuration. The quan-tities shown have the following meanings:R Random-number generatorFi FilterD 1  Delay of one discrete time unitS SubjectE Experimenteri Discrete time variableX(i) Independent sample from a uniform distributionY(i) Constrained random numberQ(i) Subject's optimum prediction for Y(i)Y(i-1) The number presented to the subject just before he gives P(i)QPR No. 68 240x(i)RFig. XXV-12. Experimental configuration.I I I I ISMEP(i) SMOOTHED MAGNITUDE OF SUBJECT'SPOLICY ERROR WITH S - 3(NOTE SCALE CHANGE ON ORDINATE)I I I I0 5 10 15 20 25 30 35 40 45 50i = DISCRETE TIME VARIABLEFig. XXV-13. Results of one human prediction experiment.QPR No. 6850 --50 1I241(XXV. NEUROLOGY)P(i) Subject's prediction for Y(i)Eg(i) Subject's guess error (=P(i)-Y(i))Ep(i) Subject's policy error (=P(i)-Q(i)).Another quantity that is not shown in Fig. XXV-11 and is also calculated by thecomputer isSSMEP(i) = S I Ep(i-j) .j=1Here, SMEP stands for "smoothed magnitude of policy error." We have found it con-venient to set S = 3 for most of our experiments.Figure XXV-13 is a graph of P(i), Y(i), and SMEP(i) (with S=3) plotted against ifor a representative sum of 50 predictions.The hypothesis has been set forth that the subject will gradually learn to behave wellwith respect to the optimum policy, but that the random character of the Y's will causehim to eventually become dissatisfied with his performance. He will then make adrastic change in his policy, which, of course, will cause his policy error to increasein magnitude. He will then gradually return to the optimum policy, only to becomedissatisfied again later on. Our experimentation has not progressed far enough to en-able us to confirm or deny this hypothesis.E. C. Van Horn, Jr., L. StarkQPR No. 68 242

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