Measurement of gonadal hormones in dried blood spots versus serum: verification of menstrual cycle phase.

In the present study, we show that blood spot assays for estradiol, progesterone, and testosterone are a reliable, accurate, and sensitive means for measuring circulating gonadal hormones. The lower limit of sensitivity of each blood spot assay is sufficient to determine gonadal hormone levels in adult females. Correspondence of serum to blood spot measures is high, with blood spot hormone levels explaining an average of 88.60% of the variance in serum gonadal hormones in females, but only 46.20% in males. We provide formulas for converting hormone levels in blood to hormone levels in serum (which traditional endocrinology studies report). Finally, we show that careful attempts to estimate hormone status by day-count methods are unreliable when compared to hormone assay in blood spots.

Adult sex differences on a decision-making task previously shown to depend on the orbital prefrontal cortex.

Monkeys and children show sex differences on tasks that depend on the orbital prefrontal cortex. To determine whether similar sex differences exist across the life span, adults were tested on an orbital-dependent decision-making task, the Iowa Card Task, as well as on a control task, the California Weather Task. In addition, estradiol, progesterone, and testosterone were assayed. The 6 groups of participants were college-age men, older men, young low-hormone (menstruating) women, young high-hormone (midluteal) women, older postmenopausal women on estrogen replacement therapy (ERT), and older postmenopausal women not on ERT. Results showed a male superiority on the Iowa Card Task. Among college-age men there was a negative correlation between performance and testosterone levels. There were no significant differences among groups of women on the card task. There were no significant sex differences or hormone correlations on the California Weather Task.

Assessing estradiol in biobehavioral studies using saliva and blood spots: simple radioimmunoassay protocols, reliability, and comparative validity.

We developed simple, reliable, and highly sensitive assay modifications of commercially available radioimmunoassay kits to measure estradiol in saliva and blood spot specimens. The saliva assay has average intra- and interassay coefficients of variation (CV) of 6.45 and 9.01%, with average analytical and serial dilution recoveries 100.65 and 89.25%. The blood spot assay has average intra- and interassay CVs of 7.57 and 8.22%, with analytical and serial dilution recoveries of 80.50 and 108.50%. The analytical sensitivity ranges of the saliva (0.25-7.50 pg/ml) and blood spot (2. 00-375 pg/ml) assays are sufficient to determine levels in the majority of pre- and postpubertal males and females. Blood spot assay results are correlated with serum estradiol levels for adult males, r (17) = 0.73, and females, r (18) = 0.96. In contrast, the serum-saliva correlation is only modest for adult females, r (14) = 0.60, and not significant for adult males. Substitution of blood spot assay results for serum values underestimates the known serum estradiol-behavior correlation by only 3.45%, whereas substitution of saliva assay results for serum values underestimates the association by 37.55%. The findings have important implications for the use and potential misuse of noninvasive measures of estradiol in studies of health and human development.

Elder law and Alzheimer's disease.

The elder-law practice focuses on the particular needs of older individuals and their families. Thus, elder law is truly "family" law because the needs of older clients are inextricably interwoven with the needs of their families. This is particularly true for the client who is chronically ill or has some form of dementia, such as Alzheimer's disease. Elder-law attorneys may now be certified to identify to the public those lawyers who demonstrate enhanced knowledge, skills, experience, and proficiency in elder law. Elder law draws from many substantive areas, such as trust, real property, agency, health care, tax, guardianship, will and probate, Social Security, Medicare, and Medicaid law. Together, the client and family are educated on legal options and are assisted in making decisions, formalized through legal documentation. The emphasis is on advance planning. Among legal practitioners, elder-law attorneys understand most clearly that the client's needs must be understood in the context of cultural and family dynamics, and addressed through a team approach involving other professions.

Sex-sensitive tasks in men and women: a search for performance fluctuations across the menstrual cycle.

This study validated 6 cognitive and motor-skill tasks as sex-sensitive and used them to investigate whether women's performance changed across the menstrual cycle. Three putative female-advantage tasks and 3 putative male-advantage tasks were administered twice, at 6-week intervals, to young college women and men. Counterbalanced for order, women received the tests once during menstruation and once during the midluteal phase. The midluteal phase was determined by projection from day of ovulation, as verified by ovulation detection kits, and by confirmation of subsequent menstruation. Results revealed a significant sex difference for 5 of the 6 tasks. However, there was no evidence that performances differed with menstrual cycle phase. These results from younger women, combined with previous results from older women, may help establish the boundaries for hormonal influences on cognitive and motor-skill behavior.

Ontogeny of place learning in children as measured in the radial arm maze, Morris search task, and open field task.

Children and adults were tested on 3 place learning tasks. Children under the age of 7 were inferior to older subjects in solving the tasks by using spatial relational solutions, but subjects of all ages were equally proficient in solving the task by using simple stimulus-reward associations (cued solutions). Accurate performance on the cued versions suggests that neither the general response demands nor the large size of testing environments rendered the tasks differentially inappropriate for young children. Instead, the nature of the cognitive demands were responsible for different levels of performance across the age groups. Because, in animal studies, spatial relational solutions but not cued solutions of these tests require mature and undamaged medial temporal lobe structures, the results suggest that these systems are not fully developed in humans before approximately 7 years of age.

Cognitive gender differences in very young children parallel biologically based cognitive gender differences in monkeys.

Infant humans were trained on 2 cognitive tests that have previously revealed, in infant monkeys, a double dissociation that was reversible by perinatal manipulations of androgens and ablations of specific brain sites. Children showed the same sex-linked behavior found with infant monkeys: young boys were superior on the object reversal task and young girls were superior on the concurrent discrimination task. As happened previously with infant monkeys, the gender difference was not apparent in older human subjects. Thus, early in ontogeny, cognitive gender differences have now been discovered in both humans and monkeys, probably a result of gender differences in androgens that influence the maturation rate of specific brain systems.

A comparison of children's performance on two recognition memory tasks: delayed nonmatch-to-sample versus visual paired-comparison.

Although 4- to 6-month-old children have a significant tendency to look at new stimuli in a visual paired-comparison task (VPC), they have difficulty in consistently choosing novel objects in a delayed nonmatch-to-sample task (DNMS). To evaluate which factors could account for this difficulty, we tested human infants (10-107 months) and adults (17-25 years) in a DNMS task while monitoring eye fixations. The results indicated that children at all ages reliably looked at (VPC scores) or chose (DNMS scores) the new stimuli about 60% of the time, indicating that both tasks measure visual recognition memory. A videotape analysis of visual attention revealed that children younger than 22 months, but not older children, spent significantly more time visually exploring the objects rather than looking at the food reward under it. Although this visual attraction to objects in children younger than 22 months of age may have impaired the formation of stimulus-reinforcer association needed to solve the DNMS task, this was not the case for older children, since beyond 22 months of age children consistently looked at the reward while displacing the objects. These results suggest that other cognitive abilities required by the DNMS task may not be fully functional even in children 22 months and older.

Picture recognition vs. picture discrimination learning in monkeys with medial temporal removals.

Three monkeys with complete ablations of temporal-lobe limbic structures and three unoperated controls were compared in an automated testing apparatus for their ability to remember pictures presented between 1 and 180 seconds previously, as well as to learn picture discriminations in which successive trials with a given pair were separated by either 20 seconds or 24 hours. The operated animals were not impaired in picture discrimination learning under either condition and they were not impaired in picture recognition memory up to about 10 seconds. At 10 seconds and beyond, however, the operated animals showed rapid deterioration of picture memory. The results demonstrate that the limbic system's selective contribution to learning and retention uncovered initially with objects applies equally to pictures, this contribution being essential for recognition memory but not for discrimination habits. The results demonstrate further that, as in humans, temporal-lobe limbic structures are essential for recognition only when the retention test exceeds the immediate memory span of a few seconds.

Performance on traditional matching to sample, non-matching to sample, and object discrimination tasks by 12- to 32-month-old children. A developmental progression.

Children 12 to 36 months old were tested on DMS, DNMS, and object discrimination tasks in a WGTA with procedures that closely followed those used previously with monkeys. Mastery of DNMS showed a clear developmental progression. The youngest children (12-15 months old) required extensive training, and they failed to reach criterion until they were 15-18 months old. The differentially slower learning of the youngest children cannot be attributed to "performance" deficits (perceptual, motivational, or associational inabilities) or the inability to make 2-part responses, because a test of object discrimination showed that even 12-month-old children can perform with accuracy in the WGTA testing situation. Analysis of learning curves along with additional tests of memory provided evidence that the youngest children are (1) less proficient in learning the novelty-reward rule and (2) less proficient in memory for a particular stimulus item. Furthermore, we found that a task that we think requires learning two rules, a DMS task, was even more difficult for children to master. These results together with data collected on brain-damaged humans and monkeys indicate that the DNMS and DMS tasks, when applied to children, may provide insight into the functional maturation of brain areas responsible for memory, rule-learning, and behavioral inhibition.

Failure to find residual memory deficits in monkeys after repeated HPNS.

Squirrel monkeys (n = 8) were equated on learning and memory tasks before sustaining 3 separate dives in a laboratory compression chamber. Associative memory was carefully monitored 1 wk before and 3 wk immediately after each dive. The first dive was a shallow, subseizure control dive and the subsequent 2 dives were deep, seizure-inducing dives. Half of the animals were always compressed in He-O2 and half in He-N2-O2 gas, which is known to increase the depth at which tremors and seizures occur. After the control dive there was a slight (10% average) decline in memory performance, but the decline was temporary and recovery was complete by the second postdive week. There was no evidence of residual memory impairments after either of the 2 subsequent seizure-inducing dives. Although addition of nitrogen to the breathing gas significantly elevated thresholds for tremors, it had no differential effect on memory scores. These results are in agreement with studies of human divers that show either no residual impairments or transient, fully recoverable cognitive symptoms after diving.

Hemispheric specialization displayed by man but not macaques for analysis of faces.

Six macaques and 20 right-handed human subjects, given identical test material, were asked to choose which of two composites, one consisting entirely of the left half of a monkey or a human face, the other of the right half, appeared most like the normal face. Confirming observations of others, the group of human subjects selected the right-half composite of the face (i.e. the left-half composite of the photograph) 68% of the time, thereby demonstrating a highly significant (P less than 0.01) bias in favor of the left visual field (right hemisphere). No such bias was present when human subjects viewed faces of monkeys, despite the fact that according to limited measurements, the faces of both species are asymmetrical. And most important, the macaques exhibited no consistent bias with either monkey or human faces. On the other hand, the monkeys did respond emotionally to these colored facial images, but not to scenery, when first presented. Also, like man, they found inverted faces but not scenery more difficult to identify than when right side up. Thus, the monkeys responded emotionally and perceptually to these images as faces, yet, unlike the human observers, displayed no hemispheric preference in making their analysis.

Disturbance of delayed match-to-sample in macaques by tetanization of anterior commissure versus limbic system or basal ganglia.

Three pig-tailed macaques were trained to select ("match") from a pair of colored images that which they had seen ("sample") and responded to 5--15 s previously. The anterior commissure (AC) and/or its radiation, various loci in basal ganglia, hippocampal formation and "control" areas, (splenium of corpus callosum, precentral gyrus, insular cortex), totalling 40 loci, were each tetanized for 4 s during presentation of the "sample" image, during the delay period, or when the monkey was required to select the "matching" image. For several loci in the hippocampal formation tetanization at any phase of the task reduced "matching" to chance levels and gave evidence of electrical after-discharge; but other comparable hippocampal loci had little or no effect. Response to "sample" or "match" stimuli were absent during tetanization of basal ganglia or anterior commissure. When finally made, upon cessation of tetanization, responses were equally correct for basal ganglia and "control" sites, but for AC were at chance levels.

Deleterious effects of prolonged electrical excitation of striate cortex in macaques.

Macaques were trained to respond to electrical excitation applied through electrodes permanently implanted within or upon striate cortex. Threshold current for the animal to detect this stimulation was highly consistent from day to day and, in the absence of tissue encapsulation of the electrodes or deliberately inflicted damage, remained stable indefinitely, 38 months in the longest case so far. Stimulating continuously for 1-8h, however, produces an elevation of threshold, which may be permanent or temporary, depending upon a variety of conditions. A major cause of such injury is the hydrolysis commonly occurring consequent to passage of low-level currents between solutions and metal electrodes. Even when the hydrolytic reaction is eliminated by restricting the level of electrode polarization or by using capacitative stimulation with tantalum pentoxide electrodes, a rise in threshold often still occurs with protracted stimulation. With proper control in some instances, however, effective stimulation at 2-10 times the threshold level could be maintained indefinitely without apparent injury, e.g. in a blind monkey having a threshold of 290 muA that could respond immediately to an 80-muA diminution in 580-muA, 0.2-msec stimulus pulses which had been applied steadily for 1 h at 50 Hz.