Graham Turpin

Cardiac and forearm plethysmographic responses to high intensity auditory stimulation

This paper reports an investigation of forearm blood flow and cardiac responses to high intensity auditory stimulation. Blood was assessed in terms of forearm girth (FG) using a strain gauge, and since this technique had not been used previously, a preliminary study was conducted to validate the measure. In Experiment 1 (N = 24), subjects performed either a fast- or slow-paced mental arithmetic task. The data indicated that the strain gauge technique differentiated periods of rest from arithmetic stress and produced results comparable with those obtained using limb volume plethysmography. In Experiment 2 (N = 24), subjects received eight presentations of either a 60 dB or a 110 dB white noise stimulus at randomly ordered intervals of 35, 40, 45 and 50 sec; stimulus rise time was 50 msec and the duration 1 sec. Both groups displayed short-latency (i.e. within 10 beats poststimulus) cardiac accelerative responses which habituated over trials. In addition, the 110dB group displayed a long-latency (19.9 sec) accelerative response of approximately 25 beats per min and this was accompanied by an increase in FG. These responses occurred only following the first stimulus presentation, and analysis of the EKG T-wave amplitude suggested that the cardiac response was mediated sympathetically. These results are discussed in terms of conceptions of the startle and defence responses in man and the fight/flight reaction in animals.

Effects of stimulus position in the respiratory cycle on the evoked cardiac response

The present experiment investigated the effects of stimulus position within the respiratory cycle on the evoked cardiac response (ECR). Two independent groups of subjects (N=14) received six presentations of a 75-dB tone of 1 sec duration and instantaneous rise time. The mean interstimulus interval was 45 sec. In one group, stimuli were presented at midinspiration, whereas in the other group stimuli were delivered during midexpiration. Heart rate (HR), skin conductance responses (SCR), and respiration were measured. Stimuli presented during midinspiration produced cardiac acceleration, whereas stimuli presented during midexpiration resulted in deceleration. These differences were substantially reduced following correction for respiratory sinus arrhythmia. The corrected ECR consisted solely of cardiac deceleration in both groups. Deceleration was largest in the inspiration group. No differences in SCRs were found. These results are discussed in terms of the “vagal gating” hypothesis.

The incremental stimulus intensity effect and habituation of evoked electrodermal responses

The present paper reports two experiments which were designed to investigate the effectiveness of a gradually increasing series of stimulus intensities for producing response habituation to a higher intensity stimulus. Experiment 1 (N = 45) employed 3-sec 1,000-Hz tones of moderate intensity, while Experiment 2 (N = 36) employed 1-sec tones of relatively high intensity. In both experiments, skin conductance was measured while subjects received a series of constant-intensity stimuli (Group C), an incremental series (Group I), or a random series (Group R). Eight trials were presented in Experiment 1, while in Experiment 2, 25 trials (5 blocks of 5 trials) were employed. The range of intensities employed for Groups I and R was 42–70 dB in Experiment 1, and 80–100 dB in Experiment 2. On the basis of previous work (O’Gorman & Jamieson, 1975), it was predicted that Group I would display smaller and fewer responses on the final trial in Experiment 1 and during the final trial block in Experiment 2 than would Groups C and R. However, neither experiment provided evidence for the “incremental stimulus intensity effect.” In Experiment 1, there were no habituation differences between the groups, while in Experiment 2, the constant series resulted in significantly greater habituation than did the incremental series for both response frequency and response amplitude.

Abstracts of papers presented at the eleventh annual scientific meeting of the psychophysiology society, Charing Cross and Westminster Medical Schools, London, December 1983Introduction

In the early classifications (Linnaeus 1758, et al.) all mayflies, constituting a single holophyletic genus Ephemera Linnaeus 1758 (placed to artificial order Neuroptera), were divided into two groups according to the number of imaginal caudalii – 3 or 2. Each of these groups was actually polyphyletic. The imaginal paracercus is developed in the majority of European Furcatergaliae and vestigial in the majority of European Tridentiseta and Branchitergaliae; thus if one studies superficially the European species only, an impression could appear that this character allows one to divide mayflies into natural groups. However, more detailed examination of mayflies reveals that representatives with 3 and 2 caudalii occur in many evidently holophyletic taxa (see Index of characters [2.3.20]). After Latreille (1802) introduces a rank of family to zoological systematics, it became possible to raise the rank of mayflies from genus to family and to attribute generic ranks to subordinated groups. In the beginning of the XIX century there were attempts to divide mayflies into subordinate groups based of presence or absence of hind wings (Leach 1815, et al.); all mayflies were divided into 4 genera: Ephemera (3 caudalii and 4 wings), Brachycercus Curtis 1834 (3 caudalii and 2 wings), Baetis Leach 1815 (2 caudalii and 4 wings) and Cloeon Leach 1815 (2 caudalii and 2 wings). However, the type species of the generic names Baetis and Cloeon appear to be related (recently both are placed to Turbanoculata), and the genus Baetis in such sense appears to be very heterogenous. Later, the number of genera was increased (Pictet 1843–1845, et al.), but the classification remained artificial. Eaton (1883–1888 et al.) made a comprehensive revision of mayfly species and suggested a new classification. His taxa diagnoses are based on adult characters only and are rather formal; larval structures are excellently illustrated but insufficiently described; for many taxa larvae were unknown or associated wrongly. It is even difficult to understand how such detailed and absolutely correct drawings of larvae could be made by the investigator, who did not know the taxonomic significance of many characters shown on them. Many supraspecies taxa established by Eaton were natural, although they did not have sufficient diagnoses. Later (Lestage 1917, et al.) ephemeropterologists paid more and more attention to larval characters rather than to imaginal ones, and established classifications based mainly or solely on larval characters. Since the artificial Linnaean order Neuroptera was completely divided into smaller natural orders (the process started by Burmeister 1829, and finished by Packard 1886 and Handlirsch 1903), mayflies got ordinal rank and were divided into a number of families and superfamilies, which in large degree corresponded to sections, series and groups proposed by Eaton (1883–1888) to the former family Ephemeridae. Basing mainly on larval characters, authors of new classifications changed many of these taxa to make the classification more natural and suggested different phylogenetic schemes (Ulmer 1920b, Edmunds & Traver 1954, Demoulin 1958, Tshernova 1970, Landa 1969, Riek 1973, et al.). Recently it is usual to accept several superfamilies, approximately from 10 to 40 families and several hundred genera. Attempts to divide mayflies into highest taxa has undergone the following evolution. 1) McCafferty and Edmunds (1979) divided all mayflies into Pannota and Schistonota, regarding Pannota to be holophyletic, and Schistonota to be paraphyletic. Even if one agrees with the phylogenetic hypothesis of these authors, this classification is not good, because here the paraphyletic taxon is larger than the holophyletic one. 2) Because of this, Kluge (1989), based on the same phylogenetic theory, suggested dividing mayflies into Furcatergalia (which included Pannota and a part of Schistonota) and Costatergalia (which included a part of Schistonota), regarding Furcatergalia to be holophyletic, and Costatergalia to be paraphyletic. In this classification, the two taxa regarded to be holophyletic and paraphyletic have subequal species numbers, which is also not good, but better than the previous classification. 3) The next step was made by McCafferty