Debra L. Johnson

Functional MRI statistical software packages: a comparative analysis.

Currently, there are many choices of software packages for the analysis of fMRI data, each offering many options. Since no one package can meet the needs of all fMRI laboratories, it is helpful to know what each package offers. Several software programs were evaluated for comparison of their documentation, ease of learning and use, referencing, data input steps required, types of statistical methods offered, and output choices. The functionality of each package was detailed and discussed. AFNI 2.01, SPM96, Stimulate 5.0, MEDIMAX 2.01, and FIT were tested. FIASCO, Yale, and MEDx 2.0 were described but not tested. A description of each package is provided. Hum. Brain Mapping 6:73–84, 1998.

The effects of lesions of the entorhinal cortex and the horizontal nucleus of the diagonal band of broca upon performance of a spatial location recognition task

The effects of lesions of the horizontal nucleus of the diagonal band of Broca (HNDB) and the entorhinal cortex (ENTO) upon performance of a spatial location recognition task were assessed. Two hypotheses of entorhinal cortex function were considered in interpretation of the data. The first hypothesis assumes that the anatomical proximity and interconnections between the hippocampus and the entorhinal cortex are indicative of a functional similarity. The second hypothesis recognizes the interconnections of the hippocampus and the entorhinal cortex, but posits that the two structures have distinct functions. The hippocampus receives input primarily from the medial septum (MS), whereas the entorhinal cortex receives input from the HNDB and the MS. The study attempted to assess the function of the ENTO and the HNDB in a spatial location recognition task with the intent of comparing the findings to previous research of the hippocampus and MS. Performance of animals with HNDB lesions and the ENTO lesions was at chance levels for all serial positions. Results indicated that there are functional differences between the HNDB and other basal forebrain structures. Further, the performance deficit of the ENTO group does not differ from that observed following lesions of the hippocampus.

Factors That Influence Effect Size in15O PET Studies: A Meta-analytic Review

The PET literature is growing exponentially, creating a need and an opportunity to perform a meta-analytic review consolidating the published information. This study describes the use of effect size as an index in PET studies and discusses how this measure can be used for comparing findings across studies, laboratories, and paradigms. In comparing studies across laboratories it is essential to know how the methods employed affect the results and conclusions drawn. This study also compared effect size for two different methods of tracer delivery in 15O PET studies ([15O]H2O bolus injection versus inhalation of [15O]CO2), whether averaged versus single-scan conditions were used, and the data analytic strategy employed. The effect sizes observed across studies were consistently large with a median effect size of 8.55, indicating that the phenomena investigated in 15O PET studies are strong. The largest peak activation reported in a study was found to be affected by variability in sample size, data analytic strategy, and repeat versus single-scan conditions. However, the impact of these factors was not examined on smaller or less intense peaks. Minimal standards for reporting statistical results are discussed.

Comparison of temporal order memory in early and middle stage Alzheimer's disease.

Four tests, each including a new learning and a prior learning component were developed to investigate temporal order memory in subjects with early and middle stage Alzheimers disease (AD). For newly learned information, both AD groups performed worse than controls but did not differ from each other. For previously learned information, the subjects with AD performed worse than controls. The early AD group performed better than the middle AD group. It appears then, that progression of the disease is associated with decreased access to knowledge systems.

An Analysis of the Basal Forebrain Contribution to Learning and Memory

In the last thirty years a large number of neural regions (e.g., hippocampus, amygdala, neocortex) have been identified as playing important roles in mediating memory. More recently, a new neural region has been discovered as a potentially important new area subserving memory function. This neural region is known as the basal forebrain area. It has gained prominence because dysfunction (cell loss) of this area may be associated with dementia of the Alzheimer’s type.