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To: - From: Su bjyect: . I ~ V ~,vVlri ~l/G{ Date: November 2, 1981 I spent twelve days working with Prof. Dr. med. K.-H. Plattig and Dr. med. G. Kobal at the Institute of Physiology be able to begin our own research without'difficulty. F.G.R. The purpose of my visit was to study olfactory evoked potential (OEP) recording techniques. Dr. Kobal tutored me in all aspects of OEP recording, and I believe that we should and Biocybernetics, Friedrich Alexander University, Erlangen, per experiment. In addition to OEPs, we also obtained psycho- physical ratings of stimulus intensity and~degree of trigeminal nerve involvement. Kobal and myself). The data were recorded on FM tape for subsequent computer analyses. -A given experiment consisted of presenting combinations of four odorants, for a total of ten times each. The wave forms so obtained were summated~, yielding four averaged OEPs PHJLIP MORRIS INCORPORATED INTER-OFFICE CORRESPONDENCE RICHHOND, Y(RGIN'JA Mr. Leo Meyer F. P. Gullotta Erlangen Trip During my first week at the Institute we performed ten experiments on five individuals (three medical students, Dr.. varying degree of detectability by anosmics. The four odorants that we studied were phenyl ethyl alcohol, citral, anethole and benzaldehyde. These were four of the eight odorants selected by Dr. Ikeda, and were chosen because of their. are being delivered. Recordings are made via scalp electrodes positioned at vertex and at mastoid (reference). Eye movements and other artifacts are carefully monitored, and stimulus pres- entations accompanied by such artifacts are eliminated in later analyses. A predetermined odorant is presented at a rate of once - every thirty to fourty seconds. The olfactometer allows for the presentation of the odorants into a constantly flowing airstream for a given stimulus duration (usually 200 msec.). The switching operation from odor-containing air to clean air cannot be perceived~by the subject, yet the stimulus rise time (20 msec) is sufficiently short to allow for computer averaging. lie quietly and breath only through the mouth while the odorants then inserted about 1.0 cm into one nostril. The subject must sound masked. A teflon tube (for stimulus presentation) is The 0EP recording technique consists of having the sub- ject recline in a shielded chamber which is ventilated and

Mr. Leo Meyer -2- November 2, 1981 Stimulus intensity is varied by mixing odor-laden air with different amounts of clean air. Psychophysical judgments of odor intensity were made by comparing the strength of each odorant to a standard. After an odorant was presented, the subject pressed a start button which controlled a light display mounted above the subject's head. The lights went on in sequence, and the subject stopped the sequence when the display matched his estimation, relative to the standard. The display controlled a digital counter which yielded numbers relatable to the subject's,.j udgments. : The subject performed a second task which reQuired that. ne estimate ttze degree of trigeminal stimulation (amount of "stitching") the odorant gave. The estimations were based on a scale ranging from zero to five,' corresponding to no tri- geminal involvement to very strong trigeminal stimulation. Four days of the second week were occupied by computer analyses of the data which we had previously gathered. This consisted of playing the taped data into a DEC PDP-11 computer, and running various programs for artifact rejection, baseline adjustments, smoothing, additive and negative transfer, plotting, etc. During my final day in Erlangen, Dr. Kobal demonstrated the recording of electrotrigem'inograms (ETGs). ETGs were ob- tained by placing an electrode up the lateral surface of the nose until it rested upon the regio res iratoria and recording the summated generator potentiao chemica stimulation of the free trigeminal nerve endings. The odorants that we employed were the same as we used for the OEP recordings. The ETG tech- nique is quite simple (with practice), and we should consider it as a supplement to our OEP work. Our preliminary findings based on ten experiments with four :odorants suggest the following tentative conclusions: (1) Differ- ent odorants appear to yield OEPs which differ in terms of lat- ency, amplitude and waveform morphology; (2) as the degree tri- geminal nerve stimulation increases the latency of the primary component.decreases and the rise time to the primary negative peak shortens (3) those odorants which purportedly have tri- geminal components depolarize the free trigeminal nerve endings in the nose. The degree of depolarization agree with the de- tectability of these odorants in anosmics. Dr. Kobal is progressing well on the work which we have funded. He will continue to record OEPs and ETGs on the four ~ odorants described above. In addition, he will test three other compounds: menthol, vanillin, C02, and the combination of van- illin and C02. This series of recordings shou prove to be very interesting. Vanillin is virtually all olfactory, whi.le C02 is,all trigeminal. By studying each OEP individually, and then by observing the combined effects, we should be able to

.~ . .,.,~' Osderie Daylor Ikeda Dunn Fagan Kallianos.. Spielberg So.uthwick ' Ennis Behavioral Research'Group P. Mr. Leo Meyer -3= November 2, 1981 .in January or February, 1982. determine how the addition of a trigeminal stimulant modifies the response to an olfactory stimulant. This information, together with ETG and psychophysical- data will be written in a comprehensive'report which we'should receive ule. The instrument should be completed in February. Work on the olfactometer which we*ordered is coming along well. Progress was somewhat slowed because Herr Bachmann (the head technician) was suffering from chronic hiccups. This was worry- some,•since much of the olfactometer is made*of handblown glass! Herr Bachmann has now recovered and work is progressing on sched- the instrument. Dr. Kobal be brought to the'U.S. to help us reassemble and debug should be shipped disassembled. Wheri it arrives, I suggest that Since the olfactometer is quite'fragile, we agreed that it cc: Dr. T. Mr. Dr. Dr. .-Dr. Dr. Mr. Mr. Dr. F. R. W. R. A. H. R. D.