Neuroexcitatory symptoms of acute poisoning of vertebrates by pyrethroids are related to the ability of these insecticides to modify electrical activity in various parts of the nervous system.Repetitive nerve activity, particularly in the sensory nervous system, membrane depolarization, and enhanced neurotransmitter release, eventually followed by block of excitation, result from a prolongation of the sodium current during membrane excitation. This effect is caused by a stereoselective and structure-related interaction with voltage-dependent sodium channels, the primary target site of the pyrethroids.Near-lethal doses of pyrethroids cause sparse axonal damage that is reversed in surviving animals. After prolonged exposure to lower doses of pyrethroids axonal damage is not observed.Occupational exposure to pyrethroids frequently leads to paresthesia and respiratory irritation, which are probably due to repetitive firing of sensory nerve endings. Massive exposure may lead to severe human poisoning symptoms, which are generally treated well by symptomatic and supportive measures.

Theories of dual cognition assume two distinguishable information processing styles: rational and intuitive. We discuss how the concepts of rationality and intuition are used in these theories, and the relations of these two thinking styles to personality characteristics. With the Rational-Experiential Inventory (REI; Pacini & Epstein, 1999 ), a questionnaire that assesses personal preferences for thinking either rationally or intuitively, we found clear evidence for the independence of the two thinking styles in a large Dutch sample (N = 774). We also found Conscientiousness to be a significant predictor of a preference for rational thinking and an inverse predictor of intuitive thinking. We also administered the REI and a Big Five inventory to a Spanish sample (N = 141), and present these results next to those of the Dutch sample. We further established the validity of the REI’s distinction between rationality and intuition by administering another measure, the Preference for Intuition or Deliberation (PID; Betsch, 2004 , 2008 ), to a subset of the Dutch sample (n = 405). We briefly describe two small studies in which a preference for rationality or intuition, measured by the REI, was found to be related to task behavior. In the general discussion we consider all results together, and compare them to Pacini and Epstein’s results. We conclude that a dual-process distinction between rationality and intuition is valid cross-culturally and that a proclivity toward either is reliably measured by the REI, not only in the USA but in Europe as well.

The stimulus response relation of the epidermal lateral-line organ of Xenopus laevis was studied by recording activity of single afferent nerve fibres in isolated preparations. Linear frequency response analysis over a frequency range of 0.1--100Hz was performed under steady-state conditions, using small amplitude, sinusoidal water displacements produced by a glass sphere at a short distance from the skin. Period histograms of afferent nerve activity were computed, and amplitude, phase and mean activity of the response were determined by means of Fourier analysis. A standardization procedure at the start of each experiment made scaling of the frequency responses of different preparations unnecessary. The results show that for small stimulus amplitudes the response of the lateral-line organ over the whole range of frequencies studied can adequately be described as a modulation of the spontaneous activity. The amplitude of the response is proportional to the stimulus amplitude, and the phase of the response is independent of stimulus amplitude. The lateral-line organ of Xenopus laevis can thus be regarded as a linear system for stimuli which produce modulation of the spontaneous activity. The frequency response demonstrates unequivocally that the lateral-line organ of Xenopus laevis functions as a water velocity detector. For frequencies of stimulation from 0.1--20Hz the gain increases with a slope of 7.5 dB/oct, and up to 5Hz the response is almost in phase with the water velocity. The extent to which the different transmission steps between stimulus and response will contribute to the frequency response is discussed.

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