Percutaneous coronary intervention or prehospital thrombolysis? What is the preferred treatment in S-T elevation myocardial infarction?

There is no situation in medicine where outcome is so utterly dependent on time than in the treatment of patients with S-T elevation myocardial infarction. This life-threatening situation accounts for 30% of acute coronary syndromes. Prompt myocardial reperfusion saves lives, but health services need to be thoroughly organised to achieve this outcome. Unfortunately, a minority of patients in Australia present within 2 h of symptom onset and most patients receive reperfusion 3-4 h after. So health professionals begin at a disadvantage. A novel approach to this problem has been to give thrombolysis at first contact with the patient, before admission to hospital. A French study has assessed this practice against the gold standard treatment for S-T elevation myocardial infarction with some very interesting results. The implications of this study now challenge well-entrenched guidelines for the management of patients with this condition.

Association of low serum anticholinergic levels and cognitive impairment in elderly presurgical patients.

Low-dose scopolamine, given as presurgery medication, resulted in low levels of serum anticholinergic activity and caused measurable cognitive impairment in 18 psychiatrically healthy elderly patients. The degree of impairment was directly related to serum anticholinergic activity levels and, in the small subgroup of patients scheduled for spinal anesthesia, to CSF anticholinergic activity. Two of the mental status tests used, the Rey Auditory-Verbal Learning Test and the Saskatoon Delirium Checklist, were sensitive enough to detect these mild drug-induced changes, while two other tests, the Mini-Mental State and the Symbol Digit Modalities Test, were not.

A signal detection procedure eliminates priming biases in dichotic listening.

Dichotic digit names were presented to normal right-handed adults in two experiments, the first of which used a standard free report procedure and the second of which used a signal detection procedure. Prior to each test, a priming bias was generated by having subjects monitor either the left or right ear for 30 selective listening trials. The expected priming effect was found in Experiment 1: ear asymmetry and order of report were altered according to the ear previously monitored. In contrast, no priming effect was observed with the signal detection procedure used in Experiment 2. There was a right-ear advantage in sensitivity irrespective of the ear previously monitored. The findings suggest that priming biases act by altering the order in which multiple stimuli are processed and reported.

Concurrent performance of rhythmically compatible or incompatible vocal and manual tasks: evidence for two sources of interference in verbal-manual timesharing.

Forty-two normal, right-handed adults performed rhythmic finger tapping with the left or right hand while concurrently reciting sentences that were either compatible or incompatible with the rhythm being tapped. Both kinds of sentences slowed tapping equally, and the interference was lateralized so that the right hand was affected more than the left. In contrast, the regularity of finger tapping was disrupted to a much greater degree by incompatible sentences than by compatible sentences, and the effect was comparable in the left and right hands. The results implicate two mechanisms of verbal-manual interference--capacity limitation and timing constraints--and thus reconcile certain inconsistencies among findings from previous concurrent-task studies.

Children's ability to shift attention from one ear to the other: divergent results for dichotic and monaural stimuli.

In three experiments, 5- to 8-year-old children reported digit names from one ear for 30 trials before shifting attention to the other ear. Stimuli were presented dichotically in Experiment 1 and monaurally in Experiments 2 and 3. Dichotic stimulation yielded not only a right-ear advantage but also a priming effect that reflects difficulty in shifting attention in either direction. With monaural stimulation, however, performance with the second ear to be monitored was superior to performance with the first ear. The priming effect thus depends on interaural competition and cannot be attributed to general factors such as fatigue or motivation.

The effect of asymmetrically focused attention upon subsequent ear differences in dichotic listening.

In a series of four experiments, normal right-handed adults engaged in dichotic listening with free-report instructions after having completed a selective listening task. The usual right-ear advantage (REA) for dichotic digit names was altered according to the ear previously monitored. Most notably, the REA was absent among subjects who had monitored the left ear. Additional experiments showed that the "priming bias" is material-specific; it did not occur if consonant-vowel nonsense syllables (CV's) were substituted for digit names in either the selective listening task or the subsequent free-report test. The findings help clarify the nature of one of the attentional mechanisms that influence auditory laterality.

The sex difference in dichotic listening: multiple negative findings.

Verbal dichotic listening tests were administered to 477 normal, right-handed adults in five consecutive experiments. None of the five separate analyses yielded a significant sex difference in degree of ear asymmetry, nor was a significant difference found when data were pooled. Supplemental analyses provided some evidence of a sex difference among subjects without familial sinistrality. Nonetheless, subjects' sex accounts for a very small proportion of the total variance in ear asymmetry.

Direction of lateral eye movements as an index of cognitive mode and emotion: a reappraisal.

Three experiments were designed to determine the effects of cognitive and emotional questions on subjective ratings, lateral eye movement (LEM) incidence and LEM direction. Although the cognitive content of questions affected subjective ratings and the incidence of LEMs, emotional content had an effect only on subjective ratings. Neither cognitive nor emotional content influenced LEM direction. The results raise doubts about the sensitivity of LEM direction as an index of lateralized cerebral processing.

The lengthy persistence of priming effects in dichotic listening.

A dichotic digits task, with selective listening instructions, was administered to 72 normal, right-handed children. The interval between monitoring one ear and monitoring the other ear was either 5 min or 1 week. Ear asymmetry depended on the order in which the ears were monitored: only children who listened first to the right ear showed a right-ear advantage. This order, or priming, effect was equally strong irrespective of the interval over which attention was switched. The results show that attentional biases may exert a strong and enduring influence on ear asymmetry.

Effects of induced anxiety and question content on the direction and frequency of lateral eye movements.

Lateral eye movements were recorded electrically as 39 right-handed adults attempted to answer 48 questions that had been rated for anxiety content, visual imagery and difficulty. Subjects were assigned randomly to either a high or low anxiety treatment group. The anxiety treatment increased ocular motility and visuospatial questioning decreased motility, but neither variable had a significant effect on the direction to which the eyes were moved. The anxiety content of questions affected neither the number nor direction of gaze shifts. The results fail to support previous claims that lateral eye movements reflect the cerebral lateralization of emotion.

Asymmetric interference between concurrent tasks: an evaluation of competing explanatory models.

According to Kinsbourne's functional cerebral distance model, asymmetric interference between concurrent cognitive and manual tasks reflects the functional specialization of the cerebral hemispheres. However, alternative explanations include initial-values artifact (statistical bias model), motor asymmetry (manual dominance model), and a combination of functional cerebral distance and manual dominance (two-factor model). We evaluated the competing models in four experiments with right- and left-handed university students for whom manual dominance was in effect reversed by requiring the dominant hand to perform the more difficult manual task. The cognitive load of the nonmanual task was varied within each experiment. The results did not support any of the models but, instead, reflected only tradeoffs between manual and nonmanual performance. The primary implications for future research are that performance on both tasks must be measured, and each task must be sensitive to interference from the other task, if observed asymmetries are to be interpretable.

Dual task performance by patients with left or right speech dominance as determined by carotid amytal tests.

Patients who had their speech dominance determined by carotid Amytal testing were evaluated with a dual task procedure consisting of reading and finger tapping. As expected, the asymmetry of interference between tasks varied with speech dominance. Patients with left hemisphere speech tended to show greater interference in the right hand whereas patients with right hemisphere speech showed greater interference in the left hand. Since the right hemisphere dominant patients were also right-handed, the results suggest that interference effects are more closely linked to speech than to motor dominance.

Ear advantage in dichotic listening after correction for early congenital hearing loss.

Twelve patients who had undergone surgical correction for either unilateral or bilateral congenital hearing loss were given a postoperative dichotic listening test for consonant vowel-consonant (CVC) words. Four normal hearing control subjects were also tested. Patients were first given a test of subjective loudness, and the level of presentation of stimuli in the atretic ear was adjusted accordingly. In the dichotic condition all controls exhibited a right ear advantage, and all unilateral atresia patients showed an ear advantage favouring the non-atretic ear. Patients with bilateral atresia essentially exhibited no ear advantage. Patients had the same error rate as controls in the dichotic condition, which suggests that ear advantage was not due to increased errors in the atretic ear. For patients there was a significant relationship between ear advantage and both preoperative interaural asymmetry in hearing loss and age at operation. Results suggest that a sensitive and critical period for development of the ear is complete by 5 years of age. Results also suggest some limited ability to adjust to permanent change in stimulation levels until, but not after, puberty.

Allocation of attention in dichotic listening: differential effects on the detection and localization of signals.

In 2 dichotic listening experiments, 96 normal right-handed adults attended selectively to the left and right ear and divided their attention equally between both ears. Participants listened for specified targets and reported the ear of entry. The material consisted of pairs of consonant-vowel syllables in Experiment 1 and pairs of rhyming consonant-vowel-consonant words in Experiment 2. Both experiments yielded a right-ear advantage for detection and for localization. Attention instructions had no effect on detection. However, focusing attention on 1 ear increased the number of targets attributed to that ear while decreasing the number of targets attributed to the opposite ear. The dissociation between detection and localization indicates that volitional shifts of attention influence late (response selection) processes rather than early (stimulus identification) processes. Selective-listening effects can be accounted for by a 2-stage model in which a fixed input asymmetry is modulated by a biased selection of responses.

Attention processes in children with shunted hydrocephalus versus attention deficit-hyperactivity disorder.

Children with congenital hydrocephalus, children with attention deficit-hyperactivity disorder, and normal controls were evaluated with measures of focused attention (Visual Orienting and Detection Task), sustained attention (continuous performance test), and attention shifting (Wisconsin Card Sorting Test). Components from these tasks have been linked to attention systems mediated by anterior or posterior brain networks. Children with congenital hydrocephalus showed an inability to focus and shift attention, which specifically implicated impairment of the disengage and move components of the posterior brain attention system. Children with attention deficit-hyperactivity disorder displayed the expected performance patterns on measures of focused attention once their difficulties with sustained attention were taken into account. However, they showed problems with shifting and sustaining attention, which are commonly associated with the anterior brain attention system.

An anomalous sex difference in auditory laterality.

Eighty right-handed adults (40 females, 40 males) performed a task that entailed detecting and localizing targets within series of dichotic digit names. Analysis of sensitivity scores for each ear revealed an overall right-ear advantage (REA). However, a significant Sex x Ear interaction showed that the degree of asymmetry was greater among females than among males. This sex difference, which is opposite to that previously reported in some dichotic listening studies, contradicts the conclusion that language processing is more completely lateralized in males than in females.

Shifts in children's ear asymmetry during verbal and nonverbal auditory-visual association tasks: a "virtual stimulus" effect.

Dichotic consonant-vowel-consonant (CVC) syllables were presented to 96 right-handed children between the ages of 8 and 12 years. Children were assigned either to a "code" condition that entailed translating the CVCs into English words or to a "bird" condition in which the CVCs had to be matched to cartoons of birds. A differential ear asymmetry for the code and bird tasks developed linearly across four blocks of trials. By Block 4, the code task yielded a significant right-ear advantage and the bird task yielded no ear advantage. The results are inconsistent with any model that attributes ear asymmetries entirely to fixed structural characteristics of the nervous system. Instead, ear asymmetries are influenced by the subject's categorization of the stimuli, i.e., by "virtual stimuli". These appear to be constructed over time (blocks of trials).

Writing posture in right hemiplegic children.

The handwriting posture of 29 children with congenital right hemiparesis was classified according to standard criteria. All 29 children, who ranged in age from 4 to 14 years, were classified unambiguously as noninverted writers. The prevalence of noninverted writing in this sample differs significantly from that reported for the general population of children. The data thus support the claim that neural factors contribute to handwriting posture.

Age-related differences in concurrent-task performance of normal adults: evidence for a decline in processing resources.

A concurrent-task paradigm was used to investigate age-related differences in the attentional capacity of 92 right-handed adults. Young, middle-aged, and elderly Ss were compared as they performed speeded, unimanual finger tapping with and without concurrent silent reading, speaking, and maze completion. There were 2 levels of difficulty for each cognitive task. The decrement in tapping rate from the single- to dual-task condition increased linearly with age. Concurrent-task tapping was slowed more by difficult than by easy tasks, and difficult tasks had a disproportionately disruptive effect on the concurrent performance of elderly Ss. The heightened vulnerability of the elderly to concurrent-task effects cannot be attributed parsimoniously to either general slowing or diminution of a specific resource. Instead the results suggest a reduction in a general-purpose processing resource with increasing age.

Adaptive and maladaptive utilization of color cues by patients with mild to moderate Alzheimer's disease.

The ability to utilize color information was investigated in 12 patients with mild to moderate probable Alzheimer's Disease (DAT) and in 12 age- and gender-matched control subjects. All subjects underwent testing of visual acuity and color vision before being tested with a cognitive task consisting of four conditions (no color, color as attention enhancer, color as valid cue, color as distracter). Although the groups did not differ in visual acuity or color vision, patients with DAT were less accurate than controls in all four conditions of the cognitive task. Both groups performed best with color as a valid cue and worst with color as distracter, but condition had a significantly stronger effect on patients than on controls. It is concluded that color is a potent stimulus attribute for patients with DAT.