Alterations in event-related potentials (ERPs) of MPTP-treated monkeys

Using an auditory ‘oddball’ paradigm and classical conditioning, we have studied auditory evoked potentials (AEPs) and P300-like potentials in monkeys pre- and post-MPTP treatment. Free-field acoustic stimuli were 500 Hz and 4000 Hz tones, which were designated as the ‘frequent’ and ‘rare’ conditions, respectively. The 4000 Hz stimuli were reinforced with mild somatosensory electrical stimulation. During the first few weeks following 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) administration, all monkeys gradually developed a parkinsonian syndrome, which partially, but not completely improved within 30–40 days in 2 animals. The amplitudes of the AEP were initially significantly decreased, but progressively returned to pretreatment magnitudes in the 2 monkeys which partially recovered. P300-like potentials were initially abolished in all animals; however, 30–40 days later P300 spontaneously re-emerged in the same 2 monkeys. Latencies of both of these signals were unaffected by MPTP. Acute administration of dopamine precursor during the first phase of neurotoxicity partially and temporarily improved depressed AEP amplitudes, but did not restore absent P300-like potentials. The relevance of these results for Parkinson's disease is discussed.     

Correlation between auditory thalamic area evoked responses and species-specific call characteristics

Evoked potentials were recorded from the posterior dorsal thalamus of green treefrogs (Hyla cinerea) in response to single tones and combinations of two and three tones. 1. The responses to two tones were largest when one of the component tones was 500 Hz and when the second component was between 2000 and 4000 Hz (Fig.3). 2. The response to 500 + 3000 Hz showed nonlinear facilitation; i.e., the amplitude of the response was greater than the sum of the responses to the component tones alone (Figs. 4, 5). This result provides evidence that cells functioning as 'AND' gates will be found in this center. 3. When a third tone around 1200 Hz was added to a stimulus of 500 + 3000 Hz a 65% decrease in the evoked response amplitude occurred (Fig. 6). 4. The largest evoked response amplitude to a two-tone stimulus (500 + 3000 Hz) occurred when the rise-time was less than 50 ms (Fig. 7). 5. The two-tone tuning was found to be temperature dependent. The optimal lower frequency tone shifted downward with decreasing temperatures (Fig. 8). 6. When the temperatures of the neurophysiological and the behavioral experiments are matched, the optimal stimuli for evoking a large response are closely correlated to the parameters of the acoustic stimuli preferred by gravid H. cinerea females in discrimination tests. This center therefore appears to be very important for the processing of complex species-specific sounds.     

Typological characteristics of conditioned reflex learning in monkeys

Three types of conditioned learning dynamics were singled out in males of the rhesus monkeys by the speed of formation of a positive motor instrumental reflex and differentiation. Type I is characterized by the fastest mastering of separate subprograms and of the whole test program of conditioned behaviour, by optimal functional characteristics in the process of learning and by a high adaptivity in new conditions. The most prolonged formation of the conditioned reflexes occurs in monkeys of the III-d type; 50% of them do not master the whole learning program; monkeys with such type of learning dynamics have no adaptation of previously acquired conditioned stereotype to new environmental conditions. Monkeys of the II-nd type of learning dynamics possess intermediate characteristics. A notion is substantiated of interconnection of higher nervous activity properties with typological characteristics of conditioned learning dynamics in monkeys.     

P300-like potentials in the normal monkey using classical conditioning and an auditory ‘oddball’ paradigm

Endogenous components of evoked potentials resembling P300 in humans were sequentially studied in 3 cynomolgus monkeys (Macaca fascicularis) using an auditory ‘oddball’ paradigm. The two different auditory stimuli were 500 Hz and 4000 Hz tones, designated as the ‘frequent’ and ‘rare’ stimuli, respectively. The probability of ‘rare’ tone presentation was initially 0.2. We further used probabilities of 0.1, 0.3 and 0.5. The ‘rare’ stimulus was reinforced by electrical stimulation, which followed the onset of the high tone by 700 msec. After 3–5 training sessions, a late positive wave was observed following the ‘rare’ tone. The latency of this P300-like signal was 314±16.2 msec, and teh amplitude 23.6±3.14 μV. The amplitude of this potential was modified by changes in stimulus presentation probability and by withholding reinforcement.     

Concomitant Pavlovian conditioning of heart rate and leg flexion responses in the rat

Pavlovian conditioning was studied in male Fischer 344 rats using tones as the conditioned stimulus (CS) and footshock as the unconditioned stimulus (UCS). Different groups of animals received (a) contiguous CS-UCS pairings with a 0.5 sec CS, (b) contiguous CS-UCS pairings with a 4.0 sec CS, or (c) a random sequence of noncontiguous tones and shocks using either a 0.5 sec or a 4.0 sec CS. Heart rate (HR) and leg flexion (LF) responses were recorded. Leg flexion conditioning occurred only in the 0.5 sec contiguous group. Decelerative HR CRs occurred only in the 4.0 sec contiguous group. Accelerative HR changes occurred in the other two groups but were significantly greater in the 0.5 sec contiguous group. These results are similar to but not identical to those obtained during eyeblink or nictitating membrane conditioning in rabbits, and suggest that the topography of the Pavlovian HR CR is dependent on the simultaneous occurrence of other classically conditioned responses.     

Conditioned taste aversion and motion sickness in cats and squirrel monkeys

The relationship between vomiting and conditioned taste aversion was studied in intact cats and squirrel monkeys and in cats and squirrel monkeys in which the area postrema was ablated by thermal cautery. In cats conditioned 7-12 months after ablation of the area postrema, three successive treatments with xylazine failed to produce either vomiting or conditioned taste aversion to a novel fluid. Intact cats, however, vomited and formed a conditioned aversion. In squirrel monkeys conditioned 6 months after ablation of the area postrema, three treatments with lithium chloride failed to produce conditioned taste aversion. Intact monkeys did condition with these treatments. Neither intact nor ablated monkeys vomited or evidenced other signs of illness when injected with lithium chloride. When the same ablated cats and monkeys were exposed to a form of motion that produced vomiting prior to surgery, conditioned taste aversion was produced and some animals vomited. These findings confirm other studies indicating motion can produce vomiting in animals with the area postrema destroyed and demonstrate that motion-induced conditioned taste aversion can be produced after ablation of the area postrema. The utility of conditioned taste aversion as a measure of subemetic motion sickness is discussed by examining agreement and disagreement between identifications of motion sickness by conditioned taste aversion and vomiting. It is suggested that a convincing demonstration of the utility of conditioned taste aversion as a measure of nausea requires the identification of physiological correlates of nausea, and caution should be exercised when attempting to interpret conditioned taste aversion as a measure of nausea.     

Dry matter disappearance and gelatinization of grains as influenced by processing and conditioning

Four ruminally cannulated steers (average body weight 430 kg) were used in a 4 × 4 split plot. Latin square design, in situ experiment to evaluate grain processing methods and effects of grain conditioner on dry matter (DM) disappearance (DMI) and degree of gelatinization of four grains. Effects of grinding or steam flaking, with and without the addition of a commercial grain conditioner, on DMD of corn (Zea mays), barley (Hordeum vulgare), wheat (Triticum vulgare) and sorghum (Sorghum vulgare) were measured at incubation times of 0, 6, 12, 24, 36 and 48 h. Degree of gelatinization of grains was determined by polarized light microscopy as loss of birefringence.

Ground grams had greater DMD than flaked grains at 0 h (sorghum, P < 0.05), 24 h (wheat, P < 0.01), 24 h (barley, P < 0.05) and 36 h (wheat, P < 0.01); however, steam flaking increased DMD at 36 h (corn, sorghum, P < 0.01) and 48 h (sorghum, P < 0.01) compared with grinding. In situ DMD was greater (P < 0.05) for ground, ground + conditioned and steam-flaked barley than for steam-flaked + conditioned barley at 24 h. Ground wheat had the greatest (P < 0.10) DMD among ground grains at 12 and 24 h; likewise, ground + conditioned wheat had the greatest (P < 0.10) DMD among ground + conditioned grains. A trend for increased DMD of wheat was observed across time, and among processing and conditioning methods, compared with other grains. Degree of gelatinization was greater for steam-flaked than for ground grains. Corn, wheat and barley reached gelatinization at lower temperatures than sorghum. These data suggest that effects of processing and conditioning varied among grains and within grains across time. Use of a commercial grain conditioner did not consistently alter DMD of grains.     

Learning-induced dynamic receptive field changes in primary auditory cortex of the unanaesthetized Mongolian gerbil

Learning-induced changes of the spectro-temporal characteristics of primary auditory cortex (AI) units were studied by response plane analysis of recordings from the AI in unanaesthetized Mongolian gerbils. Using response planes obtained prior to and after auditory discrimination training bins of significant change were identified and their spectro-temporal distribution was studied. Bins of significant changes were generally found to be distributed over the entire spectro-temporal receptive field but occurred most frequently within the first 100 ms of response in the spectral neighbourhood (1.5 octaves) of the frequency of the reinforced conditioned stimulus. Training-induced response decreases occurred early after 10 ms for reinforced conditioned tones and tones in the frequency neighbourhood. Response increases occurred so early only for non-reinforced tones in the neighbourhood of the reinforced frequency and occurred later (after 40 ms) for the reinforced tones. The results are discussed in the light of dynamic disinhibition. Accepted: 13 August 1997     

Hearing and communication in blue monkeys (Cercopithecus mitis)

Hearing and vocal communication in blue monkeys (Cercopithecus mitis) was studied within an ecological context. Field measurements of the acoustical characteristics of the blue monkey's natural habitat were conducted in the Kibale forest (Uganda) and in Kakamega forest (Kenya). Measurements of background noise levels indicated that vocal communication pitched in the 100–1000-Hz frequency band would be relatively unimpeded by disruptive background noises. Furthermore, measurements of the propagation rate of audio signals indicated that calls pitched in the 125–200-Hz region penetrated the forest with minimal decrement in amplitude. Tests of the blue monkey's acoustic sensitivyty and range of hearing were conducted in the laboratory with standard audiometric procedures. Hearing in the blue monkey was characterized by a U-shaped function, with maximum sensitivity of about 5 dB SPL spanning a four-octave range from 1 to 16 kHz. The hearing of blue monkeys was superior to human hearing for tones below 500 Hz and above 8 kHz in frequency. A comparative analysis of primate hearing indicated that the blue monkey was approximately 18 dB more sensitive to low-frequency tones than the comparably sized, semi-terrestrial rhesus monkey (Macaca mulatta). Furthermore, blue monkeys exhibit phonatory specializations for vocal production in this relatively unused, low-frequency band of 125–200 Hz. These specializations for low-frequency vocal production and low-frequency hearing collectively act to increase the effective distance of long-range acoustic communication in the forest canopy.     

Comparison of methods to stimulate ovarian follicular growth in cynomolgus and African green monkeys for collection of mature oocytes

The objective was to compare various gonadotropin-based methods to stimulate ovarian follicular growth in female cynomolgus (n=16) and African green monkeys (n=8) for collection of mature oocytes. On the 1st day of menstruation, the monkeys were treated with 3.75 mg leuprorelin acetate (a GnRH agonist). Starting 2-3 weeks later, ovarian follicular growth was stimulated as follows: (a) 25 IU/kg of human FSH (hFSH) in a glycerol solution given once daily for 9 d; (b) 200 IU of eCG given six times during a 9-d interval; (c) 75 IU/kg hFSH in a glycerol solution given three times (72 h intervals) during a 6-d interval. In addition, the monkeys were given 1200 or 4000 IU of hCG 36 h (Methods A and B) or 60 h (Method C) after the last gonadotropin treatment, and oocyte collection was attempted 36-38 h after hCG. Although there were no significant differences among methods in the number of oocytes collected, in cynomolgus monkeys, hFSH (Methods A and C) was better than eCG (Method B; 12 and 10 versus 7 mature oocytes, respectively), whereas in African green monkeys, eCG (Method B) was more effective than hFSH (Method A; 12 versus 7 mature oocytes). Furthermore, in cynomolgus monkeys, Method C was nearly as effective as Method A; using a glycerol solution as a solvent decreased the frequency of hFSH administration from nine to three times. In conclusion, in cynomolgus and African green monkeys, ovarian response depended on the species and on the individual, and in cynomolgus monkeys, hFSH in a glycerol solvent was effective.     

Overshooting cytosolic Ca2+ signals evoked by capacitative Ca2+ entry result from delayed stimulation of a plasma membrane Ca2+ pump

The effect of capacitative Ca2+ entry on cytosolic free Ca2+ concentration ([Ca2+]c) was examined in calf pulmonary artery endothelial cells treated with thapsigargin. Restoration of extracellular Ca2+ evoked an overshoot in [Ca2+]c: the initial rate of Ca2+ influx was 12.4 +/- 0.5 nM/s as [Ca2+]c rose monoexponentially (time constant, tau = 36 +/- 2 s) to a peak (322 +/- 16 nM) before declining to 109 +/- 14 nM after 2000 s. Rates of Ca2+ removal from the cytosol were measured throughout the overshoot by recording the monoexponential decrease in [Ca2+]c after rapid removal of extracellular Ca2+. The time constant for recovery (tau rec decreased from 54 +/- 4 s when Ca2+ was removed after 10 s to its limiting value of 8.8 +/- 1.0 s when it was removed after 2000 s. The time dependence of the changes in tau rec indicate that an increase in [Ca2+]c is followed by a delayed (tau = 408 s) stimulation of Ca2+ removal, which fully reverses (tau approximately 185 s) after Ca2+ entry ceases. Numerical simulation indicated that the changes in Ca2+ removal were largely responsible for the overshooting pattern of [Ca2+]c. Because prolonged (30 min) Ca2+ entry did not increase the total 45Ca2+ content of the cells, an increased rate of Ca2+ extrusion across the plasma membrane most likely mediates the Ca2+ removal, and since it persists in the absence of extracellular Na+, it probably results from stimulation of a plasma membrane Ca2+ pump. We conclude that delayed stimulation of a plasma membrane Ca2+ pump by capacitative Ca2+ entry may protect cells from excessive increases in [Ca2+]c and contribute to oscillatory changes in [Ca2+]c.     

Influence of the composition of the fusion medium on the yield of electrofused yeast hybrids

Abstract Electrofusion between cells of yeast strains with different genetic markers in isotonic sorbitol solutions leads to high yields of hybrids when 0.1 mM Ca²⁺ and 0.5 mM Mg²⁺ salts are aded. On average, 1000–2000 hybrids are obtained when electrofusion is performed (in a helical chamber) compared to a yield of about 40–120 in the absence of these bivalent cations. A further increase in yield can be achieved by the addition of 1 mg/ml albumin, which results in up to 4000 hybrids per experimental run. The entire fusion process leads to very reproducible results in the presence of these substances.     

Probability of fixation under weak selection: a branching process unifying approach

We link two-allele population models by Haldane and Fisher with Kimura's diffusion approximations of the Wright-Fisher model, by considering continuous-state branching (CB) processes which are either independent (model I) or conditioned to have constant sum (model II). Recent works by the author allow us to further include logistic density-dependence (model III), which is ubiquitous in ecology. In all models, each allele (mutant or resident) is then characterized by a triple demographic trait: intrinsic growth rate r, reproduction variance sigma and competition sensitivity c. Generally, the fixation probability u of the mutant depends on its initial proportion p, the total initial population size z, and the six demographic traits. Under weak selection, we can linearize u in all models thanks to the same master formula u = p + p(1 - p)[g(r)s(r) + g(sigma)s(sigma) + g(c)s(c)] + o(s(r),s(sigma),s(c), where s(r) = r' - r, s(sigma) = sigma-sigma' and s(c) = c - c' are selection coefficients, and g(r), g(sigma), g(c) are invasibility coefficients (' refers to the mutant traits), which are positive and do not depend on p. In particular, increased reproduction variance is always deleterious. We prove that in all three models g(sigma) = 1/sigma and g(r) = z/sigma for small initial population sizes z. In model II, g(r) = z/sigma for all z, and we display invasion isoclines of the 'mean vs variance' type. A slight departure from the isocline is shown to be more beneficial to alleles with low sigma than with high r. In model III, g(c) increases with z like ln(z)/c, and g(r)(z) converges to a finite limit L > K/sigma, where K = r/c is the carrying capacity. For r > 0 the growth invasibility is above z/sigma when z < K, and below z/sigma when z > K, showing that classical models I and II underestimate the fixation probabilities in growing populations, and overestimate them in declining populations.     

Elevated frequency of CD1c+ myeloid dendritic cells in the peripheral blood mononuclear cells of simian/human immunodeficiency virus (SHIV) and simian immunodeficiency virus (SIV) repeatedly infected Chinese rhesus macaques

CD1c+ myeloid dendritic cells (mDCs) in the peripheral blood of 30 SHIV-SF162p4 and SIVmac251 sequentially infected Chinese rhesus macaques were examined by flow cytometry to obtain further insight into mDC alterations in HIV/AIDS. The CD1c+ cells were found to be mononuclear leukocytes rather than granulocytes, and most of them expressed CD20. CD1c+mDCs (CD1c+CD20−) consisted of two morphological subsets: the granular and the large CD1c+mDCs. The expression of HLA-DR, CD86, and CD11b, but no CCR7, CD83 and CD123, together with their endocytotic capacity indicated that they were immature mDCs. Their frequency at weeks 10 and 12 post-infection was significantly higher than that of un-infected ones; the large CD1c+mDC level was significantly different between time points and almost absent from un-infected rhesus monkeys; significant correlations between CD1c+mDCs and plasma viral load levels were also observed. These data indicated a possible role for CD1c+mDCs in the pathophysiological process of SIV/HIV infection.     

The Binaural Masking-Level Difference of Mandarin Tone Detection and the Binaural Intelligibility-Level Difference of Mandarin Tone Recognition in the Presence of Speech-Spectrum Noise

Binaural hearing involves using information relating to the differences between the signals that arrive at the two ears, and it can make it easier to detect and recognize signals in a noisy environment. This phenomenon of binaural hearing is quantified in laboratory studies as the binaural masking-level difference (BMLD). Mandarin is one of the most commonly used languages, but there are no publication values of BMLD or BILD based on Mandarin tones. Therefore, this study investigated the BMLD and BILD of Mandarin tones. The BMLDs of Mandarin tone detection were measured based on the detection threshold differences for the four tones of the voiced vowels /i/ (i.e., /i1/, /i2/, /i3/, and /i4/) and /u/ (i.e., /u1/, /u2/, /u3/, and /u4/) in the presence of speech-spectrum noise when presented interaurally in phase (S₀N₀) and interaurally in antiphase (S_πN₀). The BILDs of Mandarin tone recognition in speech-spectrum noise were determined as the differences in the target-to-masker ratio (TMR) required for 50% correct tone recognitions between the S₀N₀ and S_πN₀ conditions. The detection thresholds for the four tones of /i/ and /u/ differed significantly (p<0.001) between the S₀N₀ and S_πN₀ conditions. The average detection thresholds of Mandarin tones were all lower in the S_πN₀ condition than in the S₀N₀ condition, and the BMLDs ranged from 7.3 to 11.5 dB. The TMR for 50% correct Mandarin tone recognitions differed significantly (p<0.001) between the S₀N₀ and S_πN₀ conditions, at –13.4 and –18.0 dB, respectively, with a mean BILD of 4.6 dB. The study showed that the thresholds of Mandarin tone detection and recognition in the presence of speech-spectrum noise are improved when phase inversion is applied to the target speech. The average BILDs of Mandarin tones are smaller than the average BMLDs of Mandarin tones.     

Factors Limiting Performance in a Multitone Intensity-Discrimination Task: Disentangling Non-Optimal Decision Weights and Increased Internal Noise

To identify factors limiting performance in multitone intensity discrimination, we presented sequences of five pure tones alternating in level between loud (85 dB SPL) and soft (30, 55, or 80 dB SPL). In the “overall-intensity task”, listeners detected a level increment on all of the five tones. In the “masking task”, the level increment was imposed only on the soft tones, rendering the soft tones targets and loud tones task-irrelevant maskers. Decision weights quantifying the importance of the five tone levels for the decision were estimated using methods of molecular psychophysics. Compatible with previous studies, listeners placed higher weights on the loud tones than on the soft tones in the overall-intensity condition. In the masking task, the decisions were systematically influenced by the to-be-ignored loud tones (maskers). Using a maximum-likelihood technique, we estimated the internal noise variance and tested whether the internal noise was higher in the alternating-level five-tone sequences than in sequences presenting only the soft or only the loud tones. For the overall-intensity task, we found no evidence for increased internal noise, but listeners applied suboptimal decision weights. These results are compatible with the hypothesis that the presence of the loud tones does not impair the precision of the representation of the intensity of the soft tones available at the decision stage, but that this information is not used in an optimal fashion due to a difficulty in attending to the soft tones. For the masking task, in some cases our data indicated an increase in internal noise. Additionally, listeners applied suboptimal decision weights. The maximum-likelihood analyses we developed should also be useful for other tasks or other sensory modalities.     

Weighting of Spatial and Spectro-Temporal Cues for Auditory Scene Analysis by Human Listeners

The auditory system creates a neuronal representation of the acoustic world based on spectral and temporal cues present at the listener''s ears, including cues that potentially signal the locations of sounds. Discrimination of concurrent sounds from multiple sources is especially challenging. The current study is part of an effort to better understand the neuronal mechanisms governing this process, which has been termed “auditory scene analysis”. In particular, we are interested in spatial release from masking by which spatial cues can segregate signals from other competing sounds, thereby overcoming the tendency of overlapping spectra and/or common temporal envelopes to fuse signals with maskers. We studied detection of pulsed tones in free-field conditions in the presence of concurrent multi-tone non-speech maskers. In “energetic” masking conditions, in which the frequencies of maskers fell within the ±1/3-octave band containing the signal, spatial release from masking at low frequencies (∼600 Hz) was found to be about 10 dB. In contrast, negligible spatial release from energetic masking was seen at high frequencies (∼4000 Hz). We observed robust spatial release from masking in broadband “informational” masking conditions, in which listeners could confuse signal with masker even though there was no spectral overlap. Substantial spatial release was observed in conditions in which the onsets of the signal and all masker components were synchronized, and spatial release was even greater under asynchronous conditions. Spatial cues limited to high frequencies (>1500 Hz), which could have included interaural level differences and the better-ear effect, produced only limited improvement in signal detection. Substantially greater improvement was seen for low-frequency sounds, for which interaural time differences are the dominant spatial cue.     

Comparison of the pharmacokinetics of subcutaneous and intravenous administration of a phosphorothioate oligodeoxynucleotide in cynomolgus monkeys

The pharmacokinetics of subcutaneous (s.c.) administration of a phosphorothioate oligodeoxynucleotide (PS-ODN) was evaluated in cynomolgus monkeys. In a single dose study, monkeys were injected s.c. or intravenously (i.v.) with doses of either 1 or 5 mg/kg ISIS 2302. The bioavailability of s.c. injection ranged from 26% to 55% and appeared to be dependent on the concentration of the dosing solution rather than the dose. The bioavailability of a subcutaneously administered 5 mg/kg dose of ISIS 2302 was 55% using a 50 mg/ml dosing solution and only 26% using a 10 mg/ml dosing solution. Slow absorption from the s.c. injection site significantly blunted the maximal concentration (Cmax) compared with i.v. administration. The time to peak plasma concentration (Tmax) increased slightly with increasing dose, from 0.5 to 1 hour for the 1 mg/kg dose to 1 to 2.5 hours for the 5 mg/kg dose. Plasma half-lives were prolonged after s.c. administration, indicating more dependence on absorption than elimination. The half-lives after s.c. administration averaged 3 hours, whereas after i.v. administration, the half-lives were <1 hour. Metabolism of the ISIS 2302 after s.c. injection was consistent with exonucleolytic cleavage, as previously observed after i.v. administration. In summary, s.c. administration of PS-ODN resulted in prolonged and extensive absorption of the ODN.     

Analysis of changes in the electrical activity of the neocortex in dogs during the formation of the stereotype of food-procuring conditioned reflexes in them

A system of food-procuring conditioned reflexes (dynamic stereotype after I.P. Pavlov) was elaborated in dogs. In the interstimuli periods, 0.6 to 0.8 sec. prior the action of the conditioned stimulus, they exhibited a "state of expectancy" characterized by an increase of frequency (up to 80 per sec.) of potential oscillations of a small amplitude (20 to 30 mcv) and their pronounced sychroneity, predominantly in the anterior parts of the neocortex. The conditioned signal acting against such background produced specific reactions in the form of a limited number of bursts (3 to 4 in 0.5 sec.) of highfrequency (up to 100 per sec.) synchronized activity (HSA) of considerable amplitude (50 to 60 mcv) which always preceded conditioned reactions, being in certain temporal relations with them. A correlation-spectral analysis has shown that in the HSA period, electrical activity became considerably more regular; in the intensity spectra the extreme frequencies of the analyzed band (5 to 7 c/s and 90 to 100 c/s) became prominent, and in most cases high values of the coherence function were due to them. HSA reactions are regarded as a major link in the trigger mechanism of conditioned food-procuring reactions.