bluuebunny/crossref_metadata_2025 huggingface dataset:
Event‐Related Potentials Elicited by Deviant Endings to Melodies
Authors: Paller Ken A. , McCarthy Gregory , Wood Charles C.
Published: February 2007

Event‐related potentials were recorded from scalp electrodes while subjects listened to well‐known melodies. The melodies ended either with the expected note or with a different note. This design was a nonlinguistic analogue of the design used by Kutas and Hillyard (1980b), who first reported that anomalous terminal words in sentences elicited N400 potentials. However, Besson and Macar (1987) reported that deviant terminal notes in melodies did not elicit N400 potentials. In the present study, additional time was allowed for expectations to develop for the terminal note. Deviant terminal notes did not elicit N400s. In both studies, however, the deviant notes elicited P300‐like waves. This outcome raised the possibility that N400 might have been masked by the positive potential. In a second condition in which P300 amplitude was minimized, N400s were again not evident. These results thus illustrate two additional situations in which nonlinguistic stimuli that deviated from a sequential pattern failed to elicit N400 potentials.
A Comparison between Two Methods for Assessing Heartbeat Perception
Authors: Knoll Joachim F. , Hodapp Volker
Published: February 2007

In this study two methods assessing heartbeat perception ability were compared. Subjects (N = 64) completed Schandry's (1981) mental tracking task and Störmer's (1988) heartbeat discrimination procedure (based on Whitehead, Drescher, Heiman, & Blackwell, 1977). In addition, subjects were tested on their ability to estimate the duration of time intervals. A high degree of correspondence was found between the two heartbeat perception tasks for the extreme groups of very good and very poor perceivers, but a low degree of correspondence emerged for the middle range of performance (overall r= .59, p<.001). Time estimation did not correlate significantly with either heartbeat detection procedure. Blood pressure measurements taken after the Schandry task and between Störmer test blocks showed that blood pressure amplitude was elevated among good perceivers on both heartbeat detection tasks.
Beat‐by‐Beat Cardiac Responses in Normals and Schizophrenics to Events Varying in Conditional Probability
Authors: Steinhauer Stuart R. , Jennings J. Richard , van Kammen Daniel P. , Zubin Joseph
Published: February 2007

Anticipatory cardiac deceleration and poststimulus acceleration were studied in schizophrenic inpatients and controls during performance of a counting task. Reduced cardiac responding has been reported for schizophrenic patients for paradigms using relatively long intertrial intervals. During a relatively fast rate of stimulus presentation (3‐s interstimulus interval), changes in cardiac interbeat interval were measured in 20 inpatient male chronic schizophrenics and 18 control volunteers. Subjects counted an infrequent tone which was always followed by at least one frequent tone. Control subjects showed significant anticipatory cardiac deceleration preceding the unpredictable tones, whereas patients did not show a differential cardiac deceleration. Control subjects showed poststimulus acceleration that was inversely proportional to the conditional probability of events, whereas patients exhibited greatly reduced poststimulus acceleration; patterns for both groups resembled findings previously observed for event‐related potential and pupillary dilation data. Analysis of cardiac cycle time indicated significant variation in primary bradycardia associated with the delay between stimuli and immediately preceding R‐waves in controls (replicating Lacey & Lacey, 1980), with only an immediate bradycardia at stimulus reception for patients regardless of cardiac cycle time. The data reinforce the notion that the manner in which information is used by schizophrenics, as reflected by cardiac responsivity, differs both quantitatively and qualitatively from that of controls.
Third Ventricle Enlargement and Lower Heart Rate Levels in a High‐Risk Sample
Authors: Cannon Tyrone D. , Raine Adrian , Herman Therese M. , Mednick Sarnoff A. , Schulsinger Fini , Moore Marilyn
Published: February 2007

Heart rate activity and computed tomographic measures of structural brain abnormalities were evaluated in 32 individuals with a genetic risk for schizophrenia (offspring of schizophrenic mothers). Heart rate activity was assessed in 1962 when the subjects were a mean age of 15.1 years. Diagnostic and computed tomography assessments were conducted in 1980. Compared to individuals with normal third ventricles, individuals with enlarged third ventricles evidenced significantly lower heart rate levels overall and significantly lower heart rate during rest and during the periods preceding conditioning and test for conditioning stimulus trials. These effects were independent of age, psychiatric diagnosis, and abnormalities in other brain regions. Difficulties in interpretaton posed by the index of brain abnormality employed and by the 18‐year time interval between the heart rate and computed tomography assessments are discussed. Together with prior evidence of a relationship between third ventricle enlargement and reduced electrodermal responsiveness in the same subjects, these findings provide a preliminary indication that enlargement of the third ventricle may involve damage to diencephalic structures involved in autonomic nervous system activity.
The Effect of Common Versus Distinctive Stimulus Features on Electrodermal Orientation to Significant Stimuli
Authors: Ben‐Shakhar Gershon , Gati Itamar
Published: February 2007

The relationship between electrodermal responsivity and stimulus similarity was previously demonstrated in a series of studies. These studies were guided by a feature‐matching model according to which similarity is an additive function of the common and distinctive features of the stimuli. In these experiments common and distinctive features were simultaneously manipulated, thus confounding the effects of the two sets of features. In the present experiment, we examined the separate effects of these two sets of features by an independent manipulation of common and distinctive components of the stimuli. A modified version of the guilty knowledge technique was employed, with compound pictorial and verbal stimuli (schematic faces and verbal descriptions of people) as the relevant items memorized by the subjects. Skin conductance responses were measured during the subsequent presentation of a stimulus sequence comprised of a test stimulus, which shared some common components with the relevant stimulus, and several neutral control stimuli. As hypothesized, a larger number of distinctive components resulted in decreased responsivity. Yet, contrary to our expectation, the number of common components of the relevant and test stimuli had no effect on responsivity. Several hypotheses are suggested to account for this unexpected result.
Right hemisphere representation of autonomic conditioning to facial emotional expressions
Authors: JOHNSEN BJøRN HELGE , HUGDAHL KENNETH
Published: February 2007

In this experiment, a lateralized right hemisphere effect was found for electrodermal associative learning to facial emotional expressions. Sixty‐two subjects were presented simultaneously with a slide of a happy face in the right or left visual half field (VHF) and a slide of an angry face in the opposite VHF. Four groups were formed by the combination of the two VHF positions of angry/happy faces and the administration/omission of shock unconditioned stimuli. The results showed that simultaneous presentation of the angry face to the right hemisphere and the happy face to the left hemisphere, together with shock, resulted in a strong conditioned association with the angry face and a relatively weak association with the happy face. Furthermore, simultaneous presentation of the angry face to the left hemisphere and the happy face to the right hemisphere, together with shock, resulted in a relatively weak association with both stimuli. No significant differences were found for the no‐shock control groups. The present results confirm previous findings of a right hemisphere advantage for representation of associative learning.
Visual spatial attention to stimuli presented on the vertical and horizontal meridian: An ERP study
Authors: GUNTER THOMAS C. , WIJERS ALBERTUS A. , JACKSON JANET L. , MULDER GIJSBERTUS
Published: February 2007

In the first experiment, 48 subjects carried out a visual spatial attention task. Stimuli were presented at the vertical meridian, either above or below a fixation dot, and the subjects were instructed to attend to one of these stimulus positions and ignore the other position. In three different conditions, the distances between stimulus positions and fixation were 0.5°, 0.9°, and 1.3°. Subjects searched for the presence of prememorized target letters at the attended location: memory load was one or four items in different conditions. The P1/N1 enhancement typically found on the horizontal dimension was not observed on the vertical dimension. Instead, a positive shift of the attended compared with the unattended stimuli was found, which was most prominent at anterior electrodes. This positivity showed effects of the distance manipulation. The N2b‐P3a effect of attention and the effect of memory load (search negativity) normally present in this kind of selective search task were also found. Reaction times were faster when attention was directed above fixation than when it was directed below fixation. The event‐related potential data suggested that this difference could be attributed to a more efficient neglecting of irrelevant stimuli presented below fixation. In Experiment 2, we examined whether the absence of the P1/N1 enhancement as the result of spatial attention in Experiment 1 could be attributed to (a) the presentation of stimuli along the vertical meridian instead of along the horizontal meridian, (b) the use of midline electrodes instead of lateralized electrodes, and (c) the relatively small spatial separation between the relevant and irrelevant stimuli. Twelve subjects searched for the presence of a single target letter at an attended position in three different conditions. In two of the conditions the letters were presented to the left or right of fixation. The distance between fixation and the stimulus positions was 1.3° in one of these conditions and 3° in the other condition. In the third condition, the stimuli were presented at 3° above or below fixation. In all three conditions effects similar to those in Experiment 1 were observed. In addition, in all three conditions an enhancement of the P1 and N1 components was found at two lateral occipitotemporal electrodes.
Processing of auditory stimuli during auditory and visual attention as revealed by event‐related potentials
Authors: ALHO KIMMO , WOODS DAVID L. , ALGAZI ALAIN
Published: February 2007

Auditory event‐related brain potentials (ERPs) were recorded during auditory and visual selective attention tasks. Auditory stimuli consisted of frequent standard tones (1000 Hz) and infrequent deviant tones (1050 Hz and 1300 Hz) delivered randomly to the left and right ears. Visual stimuli were vertical line gratings randomly presented on a video monitor at mean intervals of 6 s. During auditory attention, the subject attended to the stimuli in a designated ear and responded to the 1300‐Hz deviants occurring among the attended tones. During visual attention, the subject responded to the occasional visual stimuli. ERPs for tones delivered to the attended ear were negatively displaced relative to ERPs elicited by tones delivered to the unattended ear and to ERPs elicited by auditory stimuli during visual attention. This attention effect consisted of negative difference waves with early and late components. Mismatch negativities (MMNs) were elicited by 1300‐Hz and 1050‐Hz deviants irrespective of whether they occurred among attended or unattended tones. MMN amplitudes were unaffected by attention, supporting the proposal that the MMN is generated by an automatic cerebral discrimination process.
The lateralized readiness potential preceding brief isometric force pulses of different peak force and rate of force production
Authors: SOMMER WERNER , LEUTHOLD HARTMUT , ULRICH ROLD
Published: February 2007

Previous studies have reported that the lateralization of the readiness potential is unaffected by force amplitude of brief unimanual responses. However, Because those studies did not spectify rate of force production, response force probably was mainly controlled by force unit duration rather than by recruitment of force units, which may explain this negative finding. To enforce recruitment control, we factorially combined peak force (10% or 50% of maximal voluntary finger force) and time to peak force (100 or 200 ms). A precue provided advance information about the responding index finger (left vs. right). After 1 s, the imperative stimulus followed, requiring a brisk isometric flexion of the specified index finger. Symmetric effects, maximal at the vertex, of both force and rate of force production were observed 200–100 ms before the imperative stimulus in stimulus‐synchronized averages and 200–100 ms before response onset in response‐synchronized averages. However, neither force nor rate to force production affected the lateralized readiness potential. We conclude that this measure does not reflect movement parameters but appears to indicate an abstract preparation of lateralized response channels.
Modulation of spinal reflexes: Arousal, pleasure, action
Authors: BONNET MICHEL , BRADLEY MARGARET M. , LANG PETER J. , REQUIN JEAN
Published: February 2007

The human startle reflex is reliably modulated by the affective valence of foreground pictures, with larger reflexes elicited when viewing unpleasant relative to pleasant scenes. If this modulation is due to priming of the defensive startle reflex by an aversive foreground, a different pattern should occur for a reflex that is not inherently defensive in nature. In the current study, affective modulation was investigated using the spinal tendinous (T) reflex, which is well documented as sensitive to differences in arousal and is involved in actions that are both appetitively and defensively motivated. As such, T reflexes elicited during unpleasant pictures were not expected to be augmented relative to those elicited in the context of pleasant pictures. Results showed that T reflexes were facilitated during processing of arousing stimuli – either pleasant or unpleasant relative to low‐arousal neutral materials. These effects of emotional stimuli on T‐reflex amplitude are consistent with the hypothesis that motivational priming underlies affective reflex modulation.
Somatosensory responses during selective spatial attention: The N120‐to‐N140 trasition
Authors: GARCÍA‐LARREA LUIS , LUKASZEWICZ ANNE‐CLAIRE , MAUGUIÈRE FRANÇOIS
Published: February 2007

The somatosensory evoked potential negative components in the 100–150‐ms range were studied under conditions where attention was directed either toward or away from the probe stimulus. An N120 component, not sensitive to spatial attention, appeared in all conditions, including the no‐task condition. Its distribution was consistent with an origin in the second somatic area. A later N140 response, not recorded in neutral conditions, was highly sensitive to spatial attention and reached its maximum to stimulation of the attended hand; its behavior was consistent with that of a processing negativity. The N140 was bilaterally distributed, but the hemisphere contralateral to stimulation appeared to be involved earlier than the ipsilateral one. Although the exogenous N120 may be influenced by somatosensory awareness and perhaps tactile recognition, the N140 appears linked to the spatial components of attention and results from the activation of several areas in both hemispheres.
Time course and mechanisms of decreased plasma volume during acute psychological stress and postural change in humans
Authors: PATTERSON STEPHEN M. , KRANTZ DAVID S. , JOCHUM SANDRA
Published: February 2007

In this study, we examined the effects of psychological stress on calculated plasma volume, the relationship of these changes to changes in hematologic factors, and the time course of plasma volume changes. Plasma volume changes were assessed using mass densitometry techniques, which measured changes in blood and plasma density. Hematologic and hemodynamic variables were assessed in 40 healthy men and women during a mental arithmetic (math) or benign reading task and during postural change (standing). Results indicated that math and posture change produced a significant decrease in plasma volume (ps < .001) and increases in blood pressure (ps < .001), blood and plasma density (ps < .001), and total plasma protein (p < .001). Correlations were observed between plasma volume changes and changes in systolic (r= .55, p < .0001), diastolic (r= .61, p < .0001), and mean (r= .65, p < .0001) arterial pressure during math; plasma volume and blood pressure returned to baseline within 12 min following the math task. These results suggest that an important mechanism for stress‐induced decreases in plasma volume is increased blood pressure leading to increased fluid shifts from the vasculature into the interstitial spaces.
Effects of sound intensity on a midlatency evoked response to repeated auditory stimuli in schizophrenic and normal subjects
Authors: GRIFFITH JAY , HOFFER LEE D. , ADLER LAWRENCE E. , ZERBE GARY O. , FREEDMAN ROBERT
Published: February 2007

Inhibitory gating of response to repeated stimuli is demonstrated by several event‐related potentials, including the auditory P50 wave. The present study examined the effects of variation in sound intensity on this phenomenon in schizophrenics and normal subjects. Paired clicks, 500 ms apart, were presented 50 dB above threshold to 10 normal subjects and 10 schizophrenics. The normal subjects demonstrated significantly more decrement of response to the second stimulus than did the schizophrenics. When the sounds were noticeably louder(70 dB above threshold), no such difference was observed. Rather, both groups had similarly diminished gating of response. A significant difference between schizophrenics and normal subjects was also observed when the sounds were 30 dB above threshold, but the difference was smaller than that at 50 dB. At any stimulus intensity, concomitant eye movements led to loss of gating of P50 in the normal subjects.
Preparation for action: An ERP study about two tasks provoking variability in response speed
Authors: WASCHER EDMUND , VERLEGER ROLF , JASKOWSKI PIOTR , WAUSCHKUHN BERND
Published: February 2007

This study focused on the covariation of response speed and event‐related potentials during response preparation and on whether these variations can be brought under experimental control. Two S1‐S2 choice response tasks with temporal uncertainty were conducted. In Experiment I, S1 was 100% informative. Fast subjects showed larger P3s with S1 than slow subjects. The terminal CNV (tCNV) increased intraindividually with response speed. In Experiment 2.50% of S1s were uninformative and the visual display was designed to attract more attention. Effects of information were found on P3 amplitude, on the topography of tCNV, and on the temporal distribution of response times. Interindividual differences disappeared in Experiment 2. The results suggest that group differences in Experiment 1 were due to different strategies of allocating visual attention. Interindividual variations of strategy showed a pattern of effects different from intraindividual variations of efficiency.
N200 in the flanker task as a neurobehavioral tool for investigating executive control
Authors: KOPP BRUNO , RIST FRED , MATTLER UWE
Published: February 2007

Event‐related potentials were recorded in a flanker task using arrowheads pointing to the left or to the right as targets and as congruent or incongruent flanker stimuli using squares as neutral flanker stimuli. The onset of the flanker stimuli preceded that of the target stimuli byt 100 ms. Lateralized readiness potentials showed response activation below execution threshold in correspondence to the information conveyed by the flanker stimuli. Exclusively, the incongruent flanker condition provoked a N2c, which evolved closely synchronized to the erroneous response. Graded response analyses separating incongruent trials with weak, medium, and strong incorrect response activation revealed that the N2c amplitude covaried with the magnitude of the erroneous response. The N2c in the incongruent compatibility condition of the flanker task thus corresponds to the avoidance of inappropriate responses, possibly reflecting the inhibition of automatically but erroneously primed responses. The results are compatible with studies of error correction, suggesting that efference monitoring is a constituent of executive control.
Stimulus novelty and significance in electrodermal orienting responses: The effects of adding versus deleting stimulus components
Authors: GATI ITAMAR , BEN‐SHAKHAR GERSHON , AVNI‐LIBERTY SHARON
Published: February 2007

Several aspects of a feature‐matching theory formulated to account for the roles of stimulus novelty and significance in determining orienting responses (ORs) were examined. Stimulus significance and stimulus novelty were independently manipulated, and the electrodermal component of the OR was measured while sequences of compound pictorial or verbal stimuli were presented. Each sequence included a test stimulus, which was either significant or neutral, and was preceded by several standard control stimuli. Novelty was manipulated by either adding or deleting components from the standard stimuli, and significance was defined within the framework of the guilty knowledge paradigm. A change in the number of components of both verbal and pictorial test stimuli affected OR magnitude for significant but not for neutral test stimuli. Similar ORs were obtained regardless of the direction of stimulus change.
Saccades to moving targets in schizophrenia: Evidence for normal posterior cortex functioning
Authors: CLEMENTZ BRETT A.
Published: February 2007

People diagnosed with schizophrenia have abnormalities of smooth pursuit eye movement initiation that could be attributable to dysfunction of posterior cortical areas and/or the smooth pursuit regions of frontal cortex. To evaluate whether schizophrenia patients' pursuit initiation performance is most consistent with pre‐ or postrolandic neuropathology, 25 schizophrenia patients and 25 nonpsychiatric individuals were presented step‐ramp stimuli moving either away from or toward the fovea. Schizophrenia and nonpsychiatric individuals did not differ on position error of saccades to moving targets, suggesting that the schizophrenia patients did not have general difficulty with motion perception. During the initial 100 ms of smooth pursuit, however, schizophrenia patients had significantly slower eye velocities than did nonpsychiatric individuals. These results suggest that schizophrenia patients'smooth pursuit abnormalities are not associated with neuropathology of posterior cortical areas.
Phase‐sensitive interaction of cardiac and respiratory timing in humans
Authors: JENNINGS J. RICHARD , MCKNIGHT J. DANIEL , VAN DER MOLEN MAURITS
Published: February 2007

We asked whether the heart rate response to respiratory change varied as a function of timing within the cardiac cycle. Respiratory and electrocardiographic data were collected from seven men and seven women during three weekly sessions under conditions of normal and visually paced breathing. Results revealed that, when inspiration began sooner than 500 ms before the subsequent heart beat, inspiration had little effect on the subsequent interbeat interval. However, the timing of the subsequent beat was accelerated when inspiration began later than 450 ms before this heart beat. Similar relationships were observed for expiratory onset. Results were not attributable to volitional control or rate of breathing. The modulation of respiratory sinus arrhythmia by the timing of respiratory events in the cardiac cycle has implications for the role of vagal control in the synchronization of heart rate with respiratory and behavioral actions.
Neurophysiological correlates of mental arithmetic
Authors: PAULI PAUL , LUTZENBERGER WERNER , BIRBAUMER NIELS , RICKARD TIMOTHY C. , BOURNE LYLE E.
Published: February 2007

Thirteen subjects were extensively trained on nine multiplication problems varying in difficulty. Practice was associated with a reaction time speed up and an attenuation of the problem size effect. The introduction of previously unpracticed problems led to a performance rebound to pretraining levels, indicating practice specificity. The event‐related potentials were characterized by a late positive complex, followed by a positive slow wave. Offset latency of positive slow wave and preresponse amplitude at parietal electrodes showed practice specificity effects that systematically changed with practice and problem size, indicating an association with the load imposed on working memory. The peak of the late positive complex probably reflects task learning or adaptation effects because it was attenuated by practice predominantly at frontal electrodes, showed no practice specificity, and was not affected by problem size.
Bradycardia during baroreflex stimulation and active or passive stressor tasks: Cardiorespiratory fitness and hostility
Authors: GRAHAM RALPH E. , ZEICHNER AMOS , PEACOCK LELON J. , DISHMAN ROD K.
Published: February 2007

We examined whether the resting bradycardia associated with cardiorespiratory fitness extends to lowered heart rate (HR) and mean arterial pressure during novel passive or active laboratory stressors and to a longer heart period during stimulation of the carotid‐cardiac vagal baroreflex, independently of the Type A behavior pattern (TABP) and hostility. Forty‐four normotensive Caucasian men (18–35 years of age) completed the Structured Interview for TABP, the Cook‐Medley Hostility Scale, and a peak oxygen uptake (Vo2peak) test. Vo2peakwas inversely related to HR prior to, during, and after each stressor and was positively related to heart period during baroreflex testing. Hostility was inversely related to heart period during baroreflex testing. TABP had no effects. Our findings indicate that cardiorespiratory fitness and low hostility are independently associated with a bradycardia during stimulation of the carotid‐cardiac baroreflex, consistent with a possible enhancement of cardiac vagal tone.
Prepulse effects on the photic eyeblink reflex: Evidence for startle‐dazzle theory
Authors: BURKE JASON , HACKLEY STEVEN A.
Published: February 2007

Weak visual prestimulation effects on the early (R50, 50–80 ms) and late (R80, 80–200 ms) components of the eyeblink response to bright light flashes were studied in 16 normal individuals. At a lead time of 120 ms, R50 was inhibited relative to no‐prepulse control trials, whereas R80 was facilitated. According to the proposed startle‐dazzle theory, luminance onset transients trigger an initial response, R50, that is functionally related to startle. Sustained stimulation then activates prolonged eyelid (R80) and pupil responses, which serve to minimize retinal bleaching. Although the sensitivity of the photic blink reflex to attention is controversial, R50 latency showed a pattern suggestive of inhibition of return (Posner & Cohen, 1984, Attention and performance, Vol. X, pp. 531–556, Hillsdale, NJ: Erlbaum). Analyses in a patient with unilateral occipital lobe damage supported previous evidence that inhibition by a visual prepulse requires neocortex, but facilitation does not.
Temporal prominence of auditory evoked potentials (N1 wave) in 4‐8‐year‐old children
Authors: BRUNEAU N. , ROUX S. , GUÉRIN P. , BARTHÉLÉMY C. , LELORD G.
Published: February 2007

Cortical auditory evoked potentials (N1 wave) were studied in 24 adults (12 men, 12 women) and 20 children (12 boys, 8 girls; age: 4‐8 years). In adults, this wave was recorded with maximal amplitude at frontocentral sites, peaking at about 100 ms poststimulation, whereas in children the auditory response displayed maximal amplitude at the midtemporal sites, with a positive wave at about 100 ms and a large negative wave at approximately 170 ms. Moreover, the modulatory effects of intensity on N1 amplitude were prominent at frontocentral sites in adults and at temporal sites in children. Frontocentral negative response was also recorded in children but was smaller in amplitude and longer in peak latency (around 140 ms) than in adults; responses were of greater amplitude at the frontal site than at the vertex before 6 years of age, whereas the reverse was more often found after this age. These data suggest great differences with age in the neural generators contributing to auditory evoked potentials recorded in the N1 latency range.
An assessment of the discomfort associated with the use of rose bengal 1% eyedrops on the normal human eye: a comparison with saline 0.9% and a topical ocular anaesthetic
Authors: Doughty Michael J. , Lee Carole‐Ann , Ritchie Seana , Naase Taher
Published: February 2007

Purpose:  To assess the time‐dependent changes in ocular comfort following unilateral instillation of preservative‐free rose bengal 1% eyedrops when compared with saline 0.9% or proxymetacaine 0.5%.

Methods:  A total of 61 subjects, aged between 19 and 77 years, were asked to complete an ocular symptoms questionnaire, and then to indicate the comfort level for each eye on a 100‐point visual analogue scale (VAS). A single drop of rose bengal was instilled in one eye (left or right) and a drop of saline or anaesthetic instilled in the other eye. The VAS assessments were repeated at an average of 4 and 7 min later.

Results:  The instillation of rose bengal eyedrops produced an initial average reduction in comfort of 39.8 points, as compared with a reduction of 11.5 points following the anaesthetic and a reduction of 3.4 points for saline. However, the responses to rose bengal were highly variable, ranging from reductions of 1.5 to 84.6 points. In most subjects, some recovery had occurred within 6–8 min, but the comfort scores averaged 27.8 points below baseline levels prior to rose bengal. Slightly greater discomfort was noted by older subjects and those with darker irides.

Conclusions:  This study confirms that the use of rose bengal eyedrops can elicit a sensation of discomfort, but that this adverse reaction does not last very long. Based on the initial kinetics of recovery from discomfort, it is estimated that this should last no longer than 10–15 min (at least for those without significant ocular surface disease).
Acid deposition at Rothamsted, Saxmundham and Woburn, 1969–83
Authors: Goulding K. W. T. , Poulton P. R.
Published: February 2007

Abstract. Rainfall has become less acid at Rothamsted and Saxmundham over the period 1969–83. The pH of rain at these two sites has increased from 4.4–4.6 to about 4.8–4.9; at Woburn it has remained approximately constant at 4.4–4.6. Amounts of NH4‐N and NO3‐N deposited at present are 10–15 and 5–10 kg ha−1 a−1 respectively. They have been increasing at Rothamsted and Woburn. Some 50–60 kg ha−1 a−1 of Cl and 25–35 kg ha−1 a−1 of SO4‐S are presently deposited. Deposition of non‐sea Cl and SO4‐S has been increasing markedly at all three sites. Non‐sea salts comprise 35% of the total salt deposition near the coast at Saxmundham, 58% inland at Rothamsted and Woburn.
The effect of applying cobalt sulphate to soil on the cobalt content of herbage
Authors: Evans C.
Published: February 2007

Abstract. Two hill pastures in north Dyfed, Wales, were each treated at reseeding in 1971 with 2.25, 4.5 and 9.0 kg ha−1 cobalt sulphate. Herbage samples for analysis of Co content were taken in summer at each site from 1971 to 1976 and also at site 1 from 1977 to 1983. Acetic acid extractable Co was measured in soil samples taken each winter for the same period at both sites. At site 1, on a peat, the treatments continued to give worthwhile increases in herbage and soil Co after 13 years. At site 2, on a mineral soil, the residual effects were small and lasted no more than four years. It is suggested that me lower response and residual value at site 2 is due to higher levels of exchangeable and easily reducible manganese.
Yield and uptake of fertilizer nitrogen by direct‐drilled winter barley growing on a chalk soil
Authors: Christian D.G. , Crees R. , Dowdell R.J.
Published: February 2007

Abstract. This paper reports the growth and yield of grain and the utilization of fertilizer nitrogen applied on either one or two occasions in spring to a crop of winter barley established by direct drilling on a chalk soil in southern England. Nitrogen, as ammonium nitrate, was applied at rates of 0 to 140 kg N ha−1 in a range of proportions on two occasions (March and April 1981); nitrogen‐15 was used to facilitate study of the nitrogen utilization by the crop.

When sampled before the second top‐dressing in April, the greatest number of tillers were found on plants treated with 70 and 100 kg N ha−1 in March. The total above ground dry matter production at harvest was greatest when the split nitrogen dressing totalled more than 100 kg N ha−1, although the apparent efficiency of nitrogen usage (kg DM per kg N applied) was greatest when 60 kg N ha−1 was divided equally between the two application dates. Grain yield was heaviest (6.471 ha−1) at the largest rate of nitrogen applied (140 kg N ha−1); the lightest yield from the nitrogen treated crops was recorded from 100 kg N ha−1 applied as a single dressing in April that stimulated shoot production and decreased individual grain weight. The recovery in grain and straw of labelled fertilizer nitrogen applied only in March averaged 42.2% and was 49.8% when the nitrogen was applied only in April. The recovery of nitrogen applied in both March and April at the total rate of 100 kg N ha−1 but split 30/70 or 70/30 was 44.5% and 42.5% respectively. Non‐fertilizer sources of nitrogen contributed 60.7–71.7% of the total nitrogen uptake by the crop at harvest.
Factors influencing nitrogen inputs and outputs in two Scottish upland catchments
Authors: Edwards A.C. , Creasey J. , Cresser M.S.
Published: February 2007

Abstract. The factors influencing inorganic nitrogen inputs in wet deposition in two upland catchments in northeast Scotland are discussed. Seasonal trends in nitrate‐nitrogen concentrations in water draining from the catchments, and in monthly nitrate‐nitrogen outputs, are reported and explained. The inputs in rain exceeded the output in the rivers in the two catchments by 3.9–9.4 kg ha−1a−1. Retention by vegetation probably plays a crucial role in nitrogen cycling in the uplands.
Nitrogen losses from the field: denitrification and leaching in intensive winter cereal production in relation to tillage method of a clay soil
Authors: Colbourn P.
Published: February 2007

Abstract. Losses of soil and fertilizer nitrogen by leaching and denitritication from a clay soil in southern England have been measured over four years. Nitrate losses in drainage water from direct‐drilled land averaged 20–30 kg N ha ‘a’ with wide seasonal variation. Ploughing and conventional cultivations increased this loss. Denitritication from direct‐drilled land averaged 5–10 kg N ha ‘a’ with wide seasonal variation. Ploughing and drainage both diminished denitritication losses but cultivation had the greater effect. These nitrogen losses occurred mainly in autumn and spring.

Nitrogen losses, in drainage water or by denitritication after spring fertilizer applications, were related to the rainfall in the 28 days following top dressing. Approximately 40 mm rain was needed to cause a loss of 10% of the nitrogen applied but in practice losses were quite variable.
Soil degradation and management under intensive sugarcane cultivation in North Queensland
Authors: Wood A.W.
Published: February 2007

Abstract. Sugarcane yields in the Herbert Valley in North Queensland have been declining over the past 15 years. Better yields are obtained where crops are grown on previously unused land. Soils under cane are more compacted, more acid, contain less organic matter and are lower in cation exchange capacity and exchangeable cations. These differences reflect soil degradation caused by intensive cultivation.

Contributing factors to the degradation of soils include soil compaction and structural breakdown occurring during harvest and cultivation operations, losses of organic matter due to burning of crop residues and acidification of soils due to large applications of nitrogen fertilizers.

Soil management practices should aim to increase soil organic matter levels, provide a more favourable biological environment, reduce physical damage to soils during harvesting and cultivation, reduce soil acidity and improve the effectiveness of fertilizing practices.
The impact of pasture improvement on the soil solution chemistry of some stagnopodzols in mid‐Wales
Authors: Hornung M. , Stevens P.A. , Reynolds B.
Published: February 2007

Abstract. The impact of three methods of pasture improvement on soil water chemistry were studied: ploughing plus 15 t ha‐1 lime c. 40 years ago, 5 t ha‐1 surface spread lime c. 20 years ago and surface cultivation with 7 t ha‐1 lime plus compound fertilizer 10 years ago. Soil solution was sampled using tensionless lysimeters and porous ceramic cups. Concentrations of several solutes were higher in the treated soils than a control, including solutes not added in lime or fertilizers. Calcium, magnesium and bicarbonate concentrations showed the largest increases; these were apparent in all horizons, and all treatments. Bicarbonate had become the dominant anion. Solute concentrations varied between treatments and were related to the amount of an element added rather than time since treatment. Highest mean calcium concentrations, 6.25 mg l‐1 were still low compared with drainage from lowland arable soils but could have a significant impact on the calcium‐poor surface waters of the uplands.
A rationale for permeable backfill placed over pipe drains
Authors: Castle D. A.
Published: February 2007

Abstract. Much field drainage work in Great Britain includes costly permeable backfill material as a connector between mole drains, subsoiler fissures, or permeable subsoil layers and the pipe. This paper reviews the role of the Ministry of Agriculture in sponsoring research and advice on drainage design, as well as providing grant‐aid to farmers for the installation of field drainage. As a result of this involvement permeable backfill is now regarded as an essential element in the drainage of clayey soils and springs. The cost is fully justified by the establishment and maintenance of highly efficient and flexible farming systems. These techniques are applicable to many countries where clayey, slowly permeable soils predominate.
The effect of freeze/thaw on gaseous nitrogen loss from upland soils
Authors: Edwards A.C. , Killham K.
Published: February 2007

Abstract. The effect of a short‐term freeze/thaw cycle (15°C to ‐8°C to 15°C) on gaseous N‐loss (denitrification and NH3‐volatilization) from intact blocks of an upland soil is described. Rates of both denitrification and NH3‐volatilization were increased by the freeze/thaw cycle, particularly when the blocks had previously been fertilized with urea. Increased gaseous N‐loss due to freeze/thaw is reported for soils under heather and under improved grass pasture.
Principles of land appraisal and land use planning within the European Community
Authors: Verheye W.H.
Published: February 2007

Abstract. In the European Community (EC) a change towards more market‐oriented land use planning is required because of surplus stocks of cereals and dairy products, while at the same time other agricultural goods have to be imported. The implementation of such a policy has to be based on a scientifically sound and objective inventory of the physical potential of the EC as a whole.

Principles of such a physical land assessment are explained, using the concepts of the FAO‐Framework for Land Evaluation and the Agro‐ecological Zone Approach, but adapted to European conditions. The conclusions arrived at through this procedure lead to different alternatives and scenarios, and hence provide valuable background information for future land use planning.
Soil survey data needs when studying modern land use problems
Authors: Bouma J. , Lanen H.A.J. , Breeuwsma A. , Wösten H.J.M. , Kooistra M.J.
Published: February 2007

Abstract. Modern land use problems in the Netherlands are now focused on striking a balance between agricultural production, environmental protection, and nature and landscape conservation by means of new laws on soil protection. Quantitative expressions for crucial land qualities for different land management scenarios are needed to obtain adequate input for the decision making process emphasizing not only actual, but particularly potential conditions. Computer simulation techniques are being applied in this context. Three case studies are reviewed, covering: (i) adsorption of excess phosphate from animal manure; (ii) effects of lowering of water deficits for crops, and (iii) effects of soil tillage and compaction on crucial land qualities for agricultural production. Lack of representative basic data for simulation models inhibits their widespread practical application. Derivation of such basic data from existing soil‐survey databases is therefore being discussed in terms of using various types of transfer functions, which allow more effective use of available data. In addition, geographical information systems are needed to allow rapid output for areas of land as represented on soil maps.
Applications of computer modelling to predict mineral nitrogen in soil and nitrogen in crops
Authors: Whitmore A.P. , Addiscott T.M.
Published: February 2007

Abstract. A computer simulation model is described which estimates the amounts of nitrogen in the soil and winter wheat crop in spring at the time when farmers require fertilizer advice. The model has been validated against five years of experimental data on several different soil types in the east of England. Various practical applications of the model are described.
Soil water and crop production in Botswana
Authors: Jones M. J.
Published: February 2007

Abstract. This paper draws on the results of a five‐year project on the agronomy, crop physiology and soil physics of the cropping of sorghum and subsidiary crops at several sites in Botswana. The low and erratic yields usually obtained stem largely from the low and erratic rainfall, the harsh physical properties of the soils and the unfavourable interactions between these factors. Deep ploughing is essential to allow root penetration and water retrieval from depth in soils of high bulk density; sorghum plant densities must be kept moderately low, at the price of increased surface evaporation, to ensure that plants are big enough to optimize harvest index; and intercropping with cowpeas should be avoided, since it decreases sorghum yield stability with little appreciable compensation. One essential for a more stable, higher‐yielding cropping system is the year‐round management of the soil as a water storage medium. This will require the alternation of short periods of bare fallow with a sequence of crops with short and long growth cycles.
Nitrogen inputs and outputs in a small agricultural catchment in the eastern part of the United Kingdom
Authors: Roberts G.
Published: February 2007

Abstract. Nitrate concentrations measured in an ephemeral stream draining a 170 ha clay catchment in eastern England, with about 23% arable land, were greater than 11.3 mg N 1–1 on the resumption of flow each autumn but then declined. There was also a spring peak in two years out of seven, 1978–1984, which depend on the length of time soils was at field capacity in the preceding winter. Mean annual load measured in rain was 19 kg N ha‐1 and loss of nitrate in the stream 34 kg N ha‐1. A catchment nitrogen balance suggested that inputs, which averaged 130 kg N ha yr‐1, were generally more than outputs, average 108 kg N ha yr‐1', but gaseous losses were not taken into account.
Subsoil strength and yield of vegetable crops
Authors: Stone D.A.
Published: February 2007

Abstract. In a field experiment over two years, broad beans (Vicia faba), cabbage (Brassica oleracea var. capitata), leeks (Allium porrum) and red beet (Beta vulgaris var. esculenta) were grown on a sandy clay loam soil in which a range of bulk densities and penetration resistances had been established by (1) thorough loosening to 0.9 m by trenching, (2) artificially compacting with tractor wheelings or (3) leaving unloosened.

Loosening the soil substantially increased, and compacting it decreased, yields of all four crops. The mean penetration resistance of the subsoil at field capacity correlated negatively with dry matter production. The relationship was broadly similar for all crops and years, showing a decrease in dry matter production of about 1 t ha‐1 per 0.5 MPa increase in resistance over the range examined.
Estimating losses in the yield of winter wheat as a result of drought, in England and Wales
Authors: Weir A.H.
Published: February 2007

Abstract. A simple model for droughtiness, when linked to the distribution of soil types in England and Wales, is potentially valuable for estimating drought‐induced losses of yield in winter wheat at either particular places or in larger areas of the country. The model defines droughtiness, D, in terms of the soil water extractable by the crop, AP, and the adjusted potential moisture deficit, MD:

D=AP−MD.

The model should represent well the growth of actual crops of winter wheat if AP, which is based on laboratory measurements, accurately simulates the extraction of soil water by roots, if MD represents the cumulative transpiration of water by wheat crops by mid‐July, and if the latter is an appropriate date for testing the effect of drought on grain growth. These three assumptions have been investigated using measurements of artificially draughted crops of winter wheat.

The results indicate that mid‐July is a good choice for a single date and MD a good representation of the water requirement of a wheat crop that has been draughted to the point where yield is beginning to be affected. For the deep‐rooting crops studied, AP underestimates the soil water extracted by the crop, and therefore overestimates the susceptibility of the soil to drought

If average MD values are replaced by means and a standard deviation the resulting normal distribution of D‐values can be used to assess the probability that drought will limit yields. When applied to a droughtiness map of England and Wales with AP‐values used for the soils the model predicts that the soils growing wheat will be susceptible to drought in 16–84 years out of every 100. Our results suggest, however, that this probably applies to shallow rooting or diseased crops and that for deep‐rooting, healthy crops the drought risk is much less serious.
A comparison of tine cultivation and ploughing with two methods of straw disposal on the growth, nutrient uptake and yield of winter wheat grown on a clay soil
Authors: Christian D.G. , Bacon E.T.G.
Published: February 2007

Abstract. Ploughing and tine cultivation to depths of 5, 15 and 25 cm were used to prepare land before sowing winter wheat. The methods were compared for two years with or without the presence of straw residues from the previous crop and the effects on crop growth and yield were assessed.

Some combinations produced large differences in yield. In 1985–86 volunteer cereals were a problem where straw was not burnt, but deeper ploughing controlled them. In both years the concentrations and uptake of nitrogen, phosphorus and potassium differed during the early period of growth but not at maturity.