Melanoma and pregnancy: a long-term follow-up.

Treatment of the pregnant woman with melanoma is contentious. With the aid of a computerized melanoma register, in which pregnancy data can be recorded, 290 women with melanoma were reviewed (249 alive and 41 dead). Overall, 23 patients were pregnant at the time of diagnosis of melanoma, and another 23 became pregnant at some time after primary treatment of a melanoma. Pregnancy appears to have no significant influence on the survival of patients with melanoma, but it is recommended that pregnancy should be avoided for the first three years following excision of a melanoma.

Late components of auditory event-related potentials to eight equiprobable stimuli in a target detection task.

Fourteen normal subjects undertook a target detection task in which eight different but equiprobable stimuli were presented in an unpredictable sequence (four tone frequencies to either the left or the right ear). One tone/ear combination was designated as a target, to be responded to with a rapid button press. Event-related potentials were recorded from an array of six scalp electrodes. In Condition 1 no responses were required; in Condition 2 a response was required to the highest tone in one designated ear; in Condition 3 a response was required to the second highest tone in the ear opposite to the Condition 2 target. Event-related potentials to the no-task condition (1) included a P3-type late positive component. P3 increased in amplitude to target tones in Conditions 2 and 3, but showed equally large amplitude increases and some decrease in latency to nontarget tones in those conditions. However, a frontal Slow Wave component was elicited more specifically by target stimuli. An attended ear effect was evident in a processing negativity that extended for some hundreds of milliseconds prefrontally, but tended to be comprised of two separate negativities over fronto-central locations.

Brain slow potential and ERP changes associated with operator load in a visual tracking task.

Brain electrophysiological changes occurring during the course of a visual tracking task were recorded from 24 normal subjects under varying conditions of workload. Recordings were made with directly coupled amplifiers from 4 scalp midline locations and of vertical and horizontal EOG. The task was to track with a joystick a moving letter on a video monitor screen. Various decisions and button pressing responses were required from the subject during the course of each tracking trial, the total duration of a trial being 28 sec. Trial difficulty was varied by requiring identification of 'targets' or 'non-targets' based on a pre-learned 1-, 3- or 6-letter set of possible targets, by varying speed and distance travelled by the letter and by the introduction of movement perturbation. Sustained negative slow potential (SP) shifts were associated with the introduction and course of each trial. These had 2 phases: an early phase related to memorization and rehearsal and a later stage associated with the tracking itself. Increasing tracking difficulty resulted in an increased negative DC shift during the tracking stage. Increased memory set size caused a reduction in the negative shift during the preparatory, memorization phase. The experimental manipulations of difficulty also resulted in a number of changes in the amplitude and/or latency of ERP components associated with the various points of decision or response.

DC potential shift preceding repetitive perceptually relevant stimuli and its possible origin.

The Necker cube pattern was flashed repetitively with regular, 5.12 s interstimulus intervals and EEG activity was recorded by means of non-polarizable Ag/AgCl electrodes and averaged. The subjects reported the actual subjective interpretation of the pattern by pushing one of two buttons, i.e. they were motivated to interpret each stimulus. A negative potential shift (lasting about 2.5 s increasing in a more or less linear way and, reaching the final amplitude of about 11 mV), developed gradually before the stimulus onset. Positive correlation was found between the duration and amplitude of DC shift. The phenomenon described might reflect cortical processes related to expectation of a regularly repeated perceptually relevant stimulus and may be considered a version of CNV. A hypothesis interpreting the DC shift as the consequence of neuroglial processes is presented.

Brain indicators of altered attention and information processing in schizophrenic patients.

Late components of brain event-related potentials reflect aspects of selective attention, stimulus evaluation, and possibly memory update mechanisms. Several of these components were measured during an auditory target detection task, performed by 20 schizophrenic and 20 normal subjects. Both the amplitude of those components and a more general late amplitude measure were significantly reduced in schizophrenics, for both target and non-target stimuli. One general late amplitude measure, from the scalp vertex, could alone correctly classify 85% of patients and 95% of controls. The source of these differences may lie in a protracted positive potential shift.

The effects of physical and semantic incongruities on auditory event-related potentials.

Twenty subjects listened to a series of simple sentences, spoken by a male voice, in which the last word was on occasions either made semantically incongruous or was unexpectedly spoken by a female voice. Averages of ERPs to the last words revealed that a consistent late negative component (N456) was associated with semantic incongruity and a late positive component (P416) with physical (voice) incongruity. The results were consistent with those in the visual modality by Kutas and Hillyard (1980a,b) and are interpreted in terms of the facilitatory and inhibitory effects of contextual priming on the processing of the words concerned. In a subsidiary experiment 6 subjects were required to repeat the last words of the same set of sentences as rapidly as possible. Verbal response latency increased by 62 msec to physically incongruous words and by 185 msec to semantically incongruous words.

Cortical potentials associated with the detection of visual events.

A positive-going potential, which reaches a maximum at the vertex and midline parietal scalp electrodes, occurs in the human being when an infrequent, significant event occurs in a continuously observed visual display. It is not time locked to eye movements or operant response and appears to be generated when the observer recognizes an event that he has been instructed to detect.