Certain male moths flying upwind toward a scent-producing female appear to be guided anemotactically by optomotor reactions to the ground pattern. Loss of the odor stimulus changes the anemotactic angle from into wind to across wind with left-right reversals.

Counterturning' (meaning here the execution of a succession of alternating left and right turns) is the common feature in upwind zigzagging and cross-wind casting by flying insects manoeuvring towards a small source of windborne odour. Recent progress in understanding its control and function is discussed. Counterturning is internally controlled ('self-steered') in the limited sense that, once initiated by a chemical stimulus, it continues without further changes in the chemical input both in clean air and in a homogeneous cloud of odour. As a reaction it appears to be the kind of chemotaxis distinguished as longitudinal klinotaxis, for which the stimulus is a difference of chemical concentration detected over time along the insect's path, not across it. The new directions taken in response to the stimulus, being self-steered in the above sense, have no necessary relation to the direction of the chemical gradient that provided the stimulus but are influenced by the visual cues generated by wind drift. In wind, the countertuming programme is modulated by changes in the chemical input and simultaneously integrated with anemotaxis, but it can then continue in similar form after the wind has ceased. Unambiguous evidence for these conclusions is so far available only for certain flying male moths responding to sex pheromone. The primary function of countertuming, of all amplitudes and in both zigzagging and casting, appears to be the regaining of contact with an elusive scent.

Context.-Depression and ischemic heart disease often are comorbid conditions and, in patients who have had a myocardial infarction, the presence of depression is associated with increased mortality. Patients with heart disease need a safe and effective treatment for depression. Objective.-To compare the efficacy, cardiovascular effects, and safety of a specific serotonin reuptake inhibitor, paroxetine, with a tricyclic antidepressant, nortriptyline hydrochloride, in depressed patients with ischemic heart disease. Design.-Two-week placebo lead-in followed by a double-blind randomized 6week medication trial. Setting.-Research clinics in 4 university centers. Patients.-Eighty-one outpatients meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for major depressive disorder and with documented ischemic heart disease. Interventions.-Treatment with either paroxetine, 20 to 30 mg/d, or nortriptyline targeted to a therapeutic plasma level, 190 to 570 nmol/L (50-150 ng/mL), for 6 weeks. Main Outcome Measures.-For effectiveness of treatment, a decline in the score of the Hamilton Rating Scale for Depression by 50% and final score of 8 or less; for cardiovascular safety, heart rate and rhythm, supine and standing systolic and diastolic blood pressures, electrocardiogram conduction intervals, indexes of heart rate variability, and rate of adverse events. Results.-By intent-to-treat analysis, 25 (61%) of 41 patients improved during treatment with paroxetine and 22 (55%) of 40 improved with nortriptyline. Neither drug significantly affected blood pressure or conduction intervals. Paroxetine had no sustained effects on heart rate or rhythm or indexes of heart rate variability, whereas patients treated with nortriptyline had a sustained 11% increase in heart rate from a mean of 75 to 83 beats per minute (PϽ.001) and a reduction in heart rate variability, as measured by the SD of all normal R-R intervals over a 24-hour period, from 112 to 96 (PϽ.01). Adverse cardiac events occurred in 1 (2%) of 41 patients treated with paroxetine and 7 (18%) of 40 patients treated with nortriptyline (PϽ.03). Conclusions.-Paroxetine and nortriptyline are effective treatments for depressed patients with ischemic heart disease. Nortriptyline treatment was associated with a significantly higher rate of serious adverse cardiac events compared with paroxetine.

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