In order to determine the extent to which distraction disrupts performance when attention is divided, the distribution of attention across five auditory input channels was assessed using the N1 component of the human auditory evoked potential. In addition, the possibility that methylphenidate (Ritalin) affects the distribution of attention across input channels was tested. Sixteen subjects performed a tone discrimination task under conditions of focused attention and divided attention, both with and without the presence of stimuli interposed between the points to be attended. The subjects performed in two sessions during which they received either methylphenidate (10 mg) or a placebo in a double‐blind design. The results showed that the interposed stimuli were receiving some attention resulting in a disruption of performance. Methylphenidate did not affect the distribution of attention as reflected in the N1 wave. The data are interpreted as showing that: 1) distraction plays a major role in producing performance deficits observed with divided attention; and 2) methylphenidate does not appreciably affect the distribution of attention across input channels.

Performance is known to fall‐off with the time on a vigilance task. Treatment with methylphenidate attenuates this decrement while treatment with secobarbital enhances it. This experiment was designed to test whether this performance decrement and the drug effects on it are associated with changes in selective attention or in general state (i.e. motivation, alertness, or arousal). Subjects were treated with either 10 mg of methylphenidate, 100 mg of secobarbital, or a placebo in a double‐blind cross‐over design. Two event‐related potentials (N1 and P3) were measured to four tone pips presented in a random sequence. Only two of the four tones could occur in each ear. The task during the vigil was to detect a designated target tone pip. The amplitude of N1 was larger to both target and non‐target stimuli in the attended ear than to those in the unattended ear; P3 amplitude was larger only to the target stimuli. N1 amplitude decreased with time especially when secobarbital was administered. This decrement in N1 amplitude was comparable for both attended and unattended stimuli. The data support the view that the vigilance performance decrement and related drug effects on it are associated primarily with changes in general state.

The pathophysiologic process that results in bone erosion from frontal sinus mucoceles has long been a mystery. Traditionally, bone erosion has been attributed to pressure. However, no scientific evidence has yet been presented to support this hypothesis. To answer this question, seven cats had a mucocele created in one frontal sinus, with the other sinus left as a control. A manometer was inserted into each frontal sinus. Pressure readings were taken over a 7-month period. Pressures on the mucocele side were higher than on the control side and were sufficient to erode bone. Bone was thicker on the mucocele side than on the control side. This study established that mucoceles exert sufficient pressure to erode bone, and that such erosion may be part of a two-stage process.

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