BACKGROUND: Several studies from the United States and from European countries have detected sex and age differences in clinical characteristics, management, and outcomes of acute myocardial infarction. The aim of this study was to determine how sex and age influence the management of and outcome for patients with acute myocardial infarction in Japan. METHODS: A retrospective cohort study was performed by means of patient chart review at 4 teaching hospitals in Japan. There was a total of 482 patients (136 females [28%], 346 males [72%]) admitted consecutively with a diagnosis of acute myocardial infarction between July, 1995 and June, 1996. RESULTS: Female patients were older and had more comorbid diseases than male patients. Female patients also tended to have more cardiac complications during hospitalization and a greater 30-day mortality (10% vs 4%, P <.05). After adjustment for baseline characteristics and age/sex interaction, it was found that female patients were less likely to undergo thrombolytic therapy, cardiac catheterization, or revascularization, and they had a greater 30-day mortality. These sex differences in cardiac catheterization and revascularization were more pronounced for older patients. On the other hand, the sex differences in 30-day mortality were greater for younger patients. CONCLUSIONS: Our data suggest that cardiac catheterization, revascularization and 30-day mortality may have been related to patient sex and age, but further study is needed.

Neurons in the primary visual cortex (V1) detect binocular disparity by computing the local disparity energy of stereo images. The representation of binocular disparity in V1 contradicts the global correspondence when the image is binocularly anticorrelated. To solve the stereo correspondence problem, this rudimentary representation of stereoscopic depth needs to be further processed in the extrastriate cortex. Integrating signals over multiple spatial frequency channels is one possible mechanism supported by theoretical and psychophysical studies. We examined selectivities of single V4 neurons for both binocular disparity and spatial frequency in two awake, fixating monkeys. Disparity tuning was examined with a binocularly correlated random-dot stereogram (RDS) as well as its anticorrelated counterpart, whereas spatial frequency tuning was examined with a sine wave grating or a narrowband noise. Neurons with broader spatial frequency tuning exhibited more attenuated disparity tuning for the anticorrelated RDS. Additional rectification at the output of the energy model does not likely account for this attenuation because the degree of attenuation does not differ among the various types of disparity-tuned neurons. The results suggest that disparity energy signals are integrated across spatial frequency channels for generating a representation of stereoscopic depth in V4.

Horizontal binocular disparities provide information about the distance of objects relative to the point of ocular fixation and must be combined with an estimate of viewing distance to recover the egocentric distance of an object. Vergence angle and the gradient of vertical disparities across the visual field are thought to provide independent sources of viewing distance information based on human behavioral studies. Although the effect of vergence angle on horizontal disparity selectivity in early visual cortex has been examined (with mixed results), the effect of the vertical disparity field has not been explored. We manipulated the vertical disparities in a large random-dot stimulus to simulate different viewing distances, and we examined the effect of this manipulation on both the responses of neurons in the middle temporal (MT) area and on the psychophysical performance of the animal in a curvature discrimination task. We report here that alterations to the vertical disparity field have no effect on the horizontal disparity tuning of MT neurons. However, the same manipulation strongly and systematically biases the monkey's judgments of curvature, consistent with previous human studies. We conclude that monkeys, like humans, make use of the vertical disparity field to estimate viewing distance, but that the physiological mechanisms for this effect occur either downstream of MT or in a different pathway.

Processing of visual information is both parallel and hierarchical, with each visual area richly interconnected with other visual areas. An example of the parallel architecture of the primate visual system is the existence of two principal pathways providing input to the middle temporal visual area (MT): namely, a direct projection from striate cortex (V1), and a set of indirect projections that also originate in V1 but then relay through V2 and V3. Here we have reversibly inactivated the indirect pathways while recording from MT neurons and measuring eye movements in alert monkeys, a procedure that has enabled us to assess whether the two different input pathways are redundant or whether they carry different kinds of information. We find that this inactivation causes a disproportionate degradation of binocular disparity tuning relative to direction tuning in MT neurons, suggesting that the indirect pathways are important in the recovery of depth in three-dimensional scenes.

In perceptual tasks, subjects attempt to rely on their most informative cues. Such strategic choices should be reflected in the types of sensory neurons that are used. We investigated this in a binocular-disparity discrimination task. Using psychophysical reverse-correlation, also known as image classification, we identified the perceptual strategies of two macaques (Macaca mulatta). Correlations between reported disparity signs and disparity noise samples for each trial yielded detection 'filters'. Filter amplitude was greater at near disparities than at far disparities, indicating that the subjects relied more on near disparities. Recordings from both macaques' disparity-selective V2 neurons showed a correlation between neuronal responses and perceptual judgment in near-preferring, but not far-preferring, units, mirroring the psychophysically measured strategy. After one monkey learned to weight near and far disparities equally, activity in its far-preferring neurons correlated with choice. Thus, the pattern of correlations between neuronal activity and perceptual reports indicates how subjects use their neuronal signals.