Neural representations of space in the hippocampus of a food-caching bird.

Spatial memory in vertebrates requires brain regions homologous to the mammalian hippocampus. Between vertebrate clades, however, these regions are anatomically distinct and appear to produce different spatial patterns of neural activity. We asked whether hippocampal activity is fundamentally different even between distant vertebrates that share a strong dependence on spatial memory. We studied tufted titmice, food-caching birds capable of remembering many concealed food locations. We found mammalian-like neural activity in the titmouse hippocampus, including sharp-wave ripples and anatomically organized place cells. In a non-food-caching bird species, spatial firing was less informative and was exhibited by fewer neurons. These findings suggest that hippocampal circuit mechanisms are similar between birds and mammals, but that the resulting patterns of activity may vary quantitatively with species-specific ethological needs.

A comparison of stroke risk factors in patients enrolled in stroke prevention trials.

The high prevalence of stroke risk factors may explain, in part, the high incidence of stroke in African Americans. To further investigate the role of stroke risk factors, we compared stroke risk factor profiles of patients in the African-American Antiplatelet Stroke Prevention Study (AAASPS) with those in other stroke prevention studies in which the enrollees were predominately white. The baseline characteristics of the AAASPS enrollees obtained from an interim AAASPS database of 1,087 patients from 65 centers in the U.S. between December 1995 and June 1999 was compared to the baseline characteristics of 53,293 predominantly non-African American patients enrolled in 23 other stroke prevention studies (pNAA). Percentages were reported for qualitative characteristics, and means and standard deviations (SDs) for quantitative characteristics. For selected qualitative characteristics, 95% confidence intervals were given for population percentages in each study. The comparison of baseline characteristics showed that hypertension was more prevalent in AAASPS (84% [95% CI 82.2, 86.61) compared to pNAA trial patients (range of 27% to 67%). Diabetes mellitus was more common in AAASPS (39.1%) compared to pNAA trial patients (17.1%). Cardiac disease, however, was less common in AAASPS than in pNAA trials. The frequency of baseline characteristics of AAASPS patients is different from those of pNAA studies. Risk factor profiles are important as they may help to predict stroke subtype and outcome. Furthermore, the differences in baseline characteristics may portend differences in response to treatment and incidence of adverse events.

A pilot survey of African-American physician perceptions about clinical trials.

African Americans have been underrepresented in clinical trials. However, African-American physician attitudes about clinical trials may influence patient recruitment. We identified the perceptions of African-American physician members of the Cook County Physicians Association (CCPA) about clinical trials in the Chicago Metropolitan area using a self-administered questionnaire. An 18-item, 2-page survey that included information about physician demographics, practice type, and specialty, and perceptions regarding clinical research was sent to each of the 609 active or inactive members of the CCPA, a predominantly African-American physician organization. Each survey was accompanied by a letter of explanation and a self-addressed, return envelope. Data from the surveys were stored and analyzed in a database. A total of 166 members (27%) completed the survey. Fifty percent of the respondents were men and 50% were women. The mean age of the group was 45 years, and almost half had participated previously as a local investigator, or assisted on a clinical or laboratory study. Factors identified by the members as possibly being disadvantages to participation in a clinical trial, or factors influencing African-American recruitment included: (a) lack of patient awareness of clinical trials (93%); (b) patient mistrust of the medical community (92%); (c) additional administrative tasks in conjunction with a patient enrolled in a study (56%); (d) blind drug assignment (41.6%). African-American physicians perceive inherent disadvantages from participation in clinical trials and have pinpointed factors that may influence patient recruitment. These factors may be addressed by focused physician and community education.

Stroke in African Americans.

There is an excess burden of cerebrovascular disease in African Americans. This article will define possible reasons for excess stroke risk, review racial differences in stroke subtype and stroke prevention programs in the African American Community, and delineate sequelae of stroke. The authors provide insights about stroke prevention in African Americans and highlight challenges to reduce the burden of cerebrovascular disease in this high-risk group.