Habituation versus sensory adaptation as the cause of reduced attraction following pulsed and constant sex pheromone pre-exposure in Trichoplusia ni

Trichoplusia ni males receiving a pulsed regime of sex pheromone pre-exposure later, in a wind tunnel, exhibited reduced upwind flight and close approach to a sex pheromone source compared to males receiving continuous pre-exposure. Electroantennogram (EAG) amplitudes from either pulsed or continuously pre-exposed males were significantly reduced from controls only during exposure. EAG amplitudes returned within one minute after exposure to levels not significantly different from controls, indicating that habituation, not sensory adaptation was probably the cause of reduced flights under the pulsed regime. Additionally, activity levels of males during each pulsed pre-exposure remained high compared to constant or no pre-exposure males, implying that pulsing was better at achieving central nervous system habituation because it avoided adapting the receptors.     

Analysis and Modeling of Frequency-Specific Habituation of the Goldfish Vestibulo-Ocular Reflex

Modification of the vestibulo-ocular reflex (VOR) by vestibular habituation is an important paradigm in the study of neural plasticity. The VOR is responsible for rotating the eyes to maintain the direction of gaze during head rotation. The response of the VOR to sinusoidal rotation is quantified by its gain (eye rotational velocity/head rotational velocity) and phase difference (eye velocity phase—inverted head velocity phase). The frequency response of the VOR in naïve animals has been previously modeled as a high-pass filter (HPF). A HPF passes signals above its corner frequency with gain 1 and phase 0 but decreases gain and increases phase lead (positive phase difference) as signal frequency decreases below its corner frequency. Modification of the VOR by habituation occurs after prolonged low-frequency rotation in the dark. Habituation causes a reduction in low-frequency VOR gain and has been simulated by increasing the corner frequency of the HPF model. This decreases gain not only at the habituating frequency but further decreases gain at all frequencies below the new corner frequency. It also causes phase lead to increase at all frequencies below the new corner frequency (up to some asymptotic value). We show that habituation of the goldfish VOR is not a broad frequency phenomena but is frequency specific. A decrease in VOR gain is produced primarily at the habituating frequency, and there is an increase in phase lead at nearby higher frequencies and a decrease in phase lead at nearby lower frequencies (phase crossover). Both the phase crossover and the frequency specific gain decrease make it impossible to simulate habituation of the VOR simply by increasing the corner frequency of the HPF model. The simplest way to simulate our data is to subtract the output of a band-pass filter (BPF) from the output of the HPF model of the naïve VOR. A BPF passes signals over a limited frequency range only. A BPF decreases gain and imparts a phase lag and lead, respectively, as frequency increases and decreases outside this range. Our model produces both the specific decrease in gain at the habituating frequency, and the phase crossover centered on the frequency of habituation. Our results suggest that VOR habituation may be similar to VOR adaptation (in which VOR modification is produced by visual-vestibular mismatch) in that both are frequency-specific phenomena.     

Behavioral Responses of Gorillas to Habituation in the Dzanga-Ndoki National Park,Central African Republic

We monitored the impact of habituation for tourism through changes in gorillas' behavior during the habituation process at Bai Hokou (Dzanga-Ndoki National Park, Central African Republic) from August 1996 to December 1999. From August 1998 onwards we focused on one gorilla group: the Munye. During the habituation process, it became increasingly easier to locate and to remain with the gorillas. Their initial reactions of aggression, fear and vocalization upon contact were replaced increasingly by ignoring us. Curiosity appeared to be an intermediate stage in the process. The way in which contacts with the Munye ended became more subdued over time. Regular daily contact is important in promoting habituation. Likewise, contacting gorillas while they are in a tree or in dense forest provides positive results compared to open habitat. Contacts within 10 m and contacts without forewarning the gorillas of observer presence, e.g., via tongue clacking, should be avoided. As of December 1999, habituation had progressed well; habituation of western gorillas is feasible. However, the gorillas experience negative effects during the habituation process, showing, for example, an increase in daily path length, and reactions of aggression, fear and vocalization upon contact. Impacts diminish over time. Given these and other potentially negative effects, the decision to begin habituation should not be taken lightly.     

The taxonomy of neolithic man and its phylogenetic relationship to later paleolithic man and modern man in China

In approaching the taxonomy of Neolithic Man and its phylogenetic relationship to Later Paleolithic Man and Modern Man in China, the statistical methods used here are Penrose's shape distance and PCA (Principal Component Analysis). The scattergram based on principal component scores, combines the dendrogram based on Penrose's shape distance, and takes the male taxonomy into main consideration, but takes the female taxonomy — as a reference only because the differentiations in physical characteristics among male populations generally are rather larger than those among the female populations. Thus according to this scattergram, Neolithic Man in China can be divided into two large groups: the Northern China group, and the Southern China group. The theory is that in Hengzhen there exist some blood mixtures between the Southern China Group and the Northern China Group (especially the third subgroup) of Neolithic Man. Later Paleolithic Man of China — Liujiang and Upper-Cave Man — can also clearly distinguished from the rest of Neolithic Man in China in the scattergram, and can be considered as two different local types of Later Paleolithic Man. So-called “Negro-Australoid” racial traits can themselves be doubtlessly traced back to Later Paleolithic Man of China — Liujiang and Upper-cave Man. These traits are the intrinsic characteristics of Neolithic Man in China and only then is there slight difference in the extent of the manifestation of these traits in the population.     

Conditioning of slow electrocortical activity evoked by sensory stimulation and by a reflex movement in man]

Slow cerebral waves are recorded from 10 adults during an experiment consisting of the application of isolated or coupled sensorial stimulations, the weak sound occuring 880 msec prior to the strong light when coupled. Prior to coupling, the stimulations evoke on the vertex generally negative slow waves which would indicate an orientation reaction. After coupling, the responses to sound become constantly negative and are considered as waves described as "negative contingent variations". To the contrary, responses to light are inverted and become constantly positive. Such a phenomenon equally observed during experiments consisting of sound coupled to a reflex movement recalls the resolution of the negative contingent variation, the decision wave and the motor potentiel that accompanies the execution of voluntary movement, however here, it is produced during conditioning which does not require active motor participation by the subject. These results demonstrate that the simple coupling of two stimulations following the protocol developed by Pavlov provokes in man a complex collection of responses containing a motor component analogous to that which one observes in more elaborate experiments destined to prove the anticipation of the decision.     

Ranging Patterns of a Western Gorilla Group During Habituation to Humans in the Dzanga-Ndoki National Park,Central African Republic

The ranging patterns of western gorillas have been described in relation to their more frugivorous diet as compared to mountain gorillas. However, the lack of data from habituated groups prevents a full understanding of their ranging behavior and its implications for western gorilla social behavior. Unhabituated gorillas often flee from approaching researchers, possibly resulting in longer daily ranges and home range expansions and/or shifts. I report on the influence of habituation on the ranging patterns of a western gorilla group. I analyzed progress in habituation through changes in gorilla reactions, displayed upon detecting the observers. I measured daily path length and home range while following the group's trails and monitored diet via fecal analyses and direct observations. During the study period, habituation progressed and the gorillas increasingly ignored the arrival of observers. As a result, daily path lengths were longer during the early stages of habituation, when the gorillas were avoiding observers. There was no range expansion or shift, though the measure is more difficult to investigate, being subject to error due to variation in sample size. We recorded seasonal changes in the consumption of fruit by gorillas, but no direct effect on ranging patterns is detectable with the data available, which is likely a consequence of the combined effect of habituation and seasonality on group movements. The findings are not only important for understanding the extent of human influence while conducting research on wild gorillas but also suggest the need for caution when interpreting results from non-habituated gorillas.     

Morphological characteristics of the spermatogonial stem cells in man

The present investigation is concerned with establishing morphological criteria of spermatogonial stem cells in man. Testicular biopsies from patients having undergone semicastration for malignant tumors and radio- and chemotherapy for one year following the operation were studied light and electron microscopically. Those spermatogonial types that survived the treatment were regarded as stem cells in view of the fact that the stem cells, in contrast to the more differentiated spermatogonia, are radiation resistant and less sensitive to various noxious agents. In 7 out of 28 cases examined, a small number of spermatogonia was found adjacent to the basement membrane. The majority of these cells show the characteristic features of pale type A spermatogonia, while a few cells may represent variants of this cell type. The dark type A spermatogonia are almost completely eliminated from the seminiferous tubules. A concept is proposed that the stem cells of the human testis may be derived from the pale type A spermatogonia or the variants of this cell type.     

Cerebral-evoked responses elicited by direct stimulation of the lateral spinothalamic tract in the human

The authors recorded cerebral-evoked responses elicited by direct stimulation of the human lateral spinothalamic tract (LST) during percutaneous cordotomy to investigate central conduction of noxious stimuli. These responses consisted of four negative potentials, peak latency being 3.8 (N1), 8.4 (N2), 12.2 (N3) and 21.9 (N4) ms respectively. N1 showed wide distribution over the scalp and was considered to be of subcortical origin. N2-N4 were distributed in both the temporal and central area. The different distribution pattern of N2-N4 from conventional somatosensory-evoked potential suggested a different projection of LST from the medial lemniscus system.     

Immunofluorescence study of LRF neurons in man

Summary Human LRF neurons were characterized by immunofluorescence, using rabbit immunesera against unconjugated synthetic LRF, previously adsorbed on polyvinylpyrrolidone.These neurons, which vary in number from one specimen to another, are mainly concentrated in the mediobasal hypothalamus (infundibular and premammillary nuclei in particular) and in the lamina terminalis and the neighbouring preoptic area. They give rise respectively to a hypothalamoinfundibular LRF tract (ending around the capillaries of the primary portal plexus of the infundibulum) and to a preoptico-terminal tract (ending mainly around the capillaries of the primary and secondary plexuses of the vascular organ of the lamina terminalis and, in addition, between the ependymal cells lining its ventricular surface). It is suggested that these two tracts could be implicated in the tonic and cyclic control of gonadotropic secretion.Some reactive neurons are also present in the septal and pericommissural regions and in the retromammillary area and rostral mesencephalon. These neurons give rise to various extrahypophyseal LRF tracts, probably ending in the telencephalon and the brainstem. It is suggested that LRF, in addition to its major prehypophysiotropic action, is able to modulate the activity of certain telencephalic or mesencephalic structures.I should like to thank Dr. E. Farkas (Head of U. 154 INSERM and Laboratory of Neuropathology, Saint Vincent de Paul Hospital, Paris), Prof. Müller (Head of the Institute of Forensic Medicine, Lille) and collaborators (Ag. Prof. Lenoir, Drs. Debarge and Willot) and Prof. Delecour (Head of Salengro Maternity, Lille) for kindly providing human hypothalami     

Increase on the coronary flow induced by dioclein in isolated rat heart

In the present work the effect of dioclein, a new flavonoid from Dioclea grandiflora, was investigated in rat hearts. The experiments were performed using the classic method of Langendorff, where flow, inotropic, chronotropic and electric parameters were analyzed. Bolus administration of Dioclein (1-100 microg) induced a sustained and dose-dependent increase in coronary flow with no modification in inotropic, chronotropic and electrical parameters. The duration of increase in coronary flow induced by dioclein (10 microg) was approximately 4-fold higher than that observed in the presence of sodium nitroprusside (NPS; 10 microg). Besides, the effect of dioclein measured as the area-under-the-curve was approximately 4.5-folds higher than that observed with NPS. Pre-treatment with L-NAME (100 microM) and indomethacin (10 microM) alone did not modify the effect of dioclein (10 microg), suggesting that nitric oxide (NO) and cyclooxygenase-derived factors were not involved. However, association of L-NAME plus indomethacin inhibited the duration of the effect of dioclein (10 microg) without changing its increase in the coronary flow. Furthermore, the absence of alteration in inotropism and chronotropism of the heart associated with its coronary effect suggest that dioclein could be an interesting lead compound for the development of drugs for the treatment coronary heart diseases.     

Latitude-related changes in the amplitude of annual mortality rhythm. The biological equator in man

There is extensive literature describing the effect of season on mortality rates, especially in cardiovascular and respiratory disease. This study compares latitude with the extent of seasonal variation of monthly deaths from all causes. In developed countries, there is a peak of deaths in winter and a trough in summer. Monthly numbers of deaths were established in 89 countries in the Northern and Southern Hemisphere. Using cosinor analysis, the extent of seasonal variation (amplitude) was established and correlated with latitude. The amplitude of seasonality was greatest in mid-latitude around 35°, but low or absent near the equator and subpolar regions. The amplitude can differ at the same latitude. The weather in equatorial regions and in habitations near the Arctic Circle is very different, but death has a similar seasonal rhythm. The purpose is to record this epidemiological finding even though no simple explanation is provided. Weather alone cannot explain it, and it is possible that day length (photoperiod) has an important, but complex, underlying role.     

Role of nitrosyl factors in the hindlimb vasodilation elicited by baroreceptor afferent nerve stimulation

This study determined whether electrical stimulation (ES) of the baroreceptor afferent fibers in the aortic depressor nerve (ADN) produces hindlimb vasodilation in pentobarbital-anesthetized rats via the release of nitric oxide (NO)-containing (nitrosyl) factors from NO synthase-positive lumbar sympathetic nerve terminals. ES of the ADN (1-10 Hz for 15 s) produced frequency-dependent reductions in mean arterial blood pressure (MAP) and mesenteric and hindlimb vascular resistance (MR and HLR, respectively). The falls in resistance were substantially smaller in hindlimb beds in which the ipsilateral lumbar sympathetic chain had been transected 7-10 days previously. The maximal falls in MR and hindquarter vascular resistance (HQR) produced by 1- to 10-Hz ES of the ADN were unaffected by the specific inhibitor of neuronal NO synthase 7-nitroindazole (7-NI, 45 mg/kg iv). However, the total falls in HQR (mmHg.kHz(-1).s) produced by these stimuli were significantly diminished by 7-NI, whereas the total falls in MR were not affected. Four successive episodes of 10-Hz ES produced equivalent reductions in MAP, MR, and HQR. The peak changes in these parameters were not affected by 7-NI. However, the total falls in HQR progressively diminished with each successive stimulus, whereas the total falls in MR remained unchanged. These results provide evidence that the hindlimb vasodilation produced by ES of baroreceptor afferents within the ADN may involve the activation of postganglionic lumbar sympathetic vasodilator fibers, which release newly synthesized and preformed nitrosyl factors.     

Distinct hemodynamic and gastric effects of human CGRP I and II in man

The human calcitonin gene-related peptides I and II (or and β) (CGRP I and II) are encoded by two different genes, but they have 34 of the 37 amino acid residues in common. Human CGRP I more potently stimulated blood flow through the skin and carotid artery (p<0.01), and the heart rate (p<0.05), and plasma renin activity and aldosterone secretion than human CGRP II (p<0.02). Inhibition of pentagastrin-stimulated gastric acid output, on the other hand, was only obtained with CGRP II. The separate effects of human CGRP I and II on the cardiovascular and gastric systems are presumably mediated by different receptors or receptor pathways recognized by the two closely related neuropeptides.     

Emotional and social behaviors elicited by electrical stimulation of the insula in the macaque monkey

Evidence from a large number of brain imaging studies has shown that, in humans, the insula, and especially its anterior part, is involved in emotions and emotion recognition. Typically, however, these studies revealed that, besides the insula, a variety of other cortical and subcortical areas are also active. Brain imaging studies are correlative in nature, and, as such, they cannot give indications about the necessary contribution of the different centers involved in emotions. In the present study, we aimed to define more clearly the role of the insula in emotional and social behavior of the monkey by stimulating it electrically. Using this technique, one may determine whether direct activation of the insula can produce specific emotional or social behaviors and exactly which parts of this structure are responsible for these behaviors. The results showed that two emotional behaviors, a basic one (disgust) and a social one (affiliative state), were easily elicited by electrical stimulation of specific parts of the insula. Both behaviors were characterized by specific motor and vegetative responses and by a dramatic change in the monkey's responsiveness to external stimuli.     

Osmotic thirst suppression elicited by electrical stimulation of the basal forebrain in the dog.

Reactivity of the thirst mechanism to osmotic stimuli was measured in conscious dogs chronically implanted with electrodes in the basal forebrain. It was found that the thirst threshold to the osmotic stimulus increases markedly during electrical stimulation of the preoptic area, septum, nucleus accumbens septi, and to smaller degree during stimulation of the nucleus caudatus. The possibility of existence of some inhibitory components in the neural system controlling thirst in the dog is suggested.     

Characteristics of hypotension elicited by electrical stimulation of the lateralhypothalamusin anaesthetized dogs.

Electrical stimulation of the lateral hypothalamus near the paraventricular nucleus hypothalami, resulted in : hypotension, light bradycardia, decrease of the left ventricular systolic pressure without increase of the left ventricular end-diastolic pressure or left ventricular output, femoral vasodilatation and occasionally renal vasodilatation. The hypotensive reactions were potentiated by baroreceptor deafferentation. They were not blocked by anticholinergic, antihistaminic or antidopaminergic agents.