Pathways between the dorsal lateral geniculate nucleus (dLGN) and visual cortex in Old World (Macaca, Papio, Erythrocebus, Cercopithecus) and New World (Saimiri, Cebus) primates were studied after injections of horseradish peroxidase and H3 or S35 amino acids into the dLGN or visual cortex. Trans-synaptic autoradiography was also used to study these pathways after an injection of H3 proline-fucose into one eye. The subsequent autoradiographs of visual cortex showed that Old World primates have separate eye inputs (ocular dominance columns) in the striate cortex, whereas New World monkeys have overlapping or non-separated eye inputs. In both primate groups the geniculocortical input to layer IVA formed a pattern which resembled a honeycomb in tangential sections, unlike the solidly labeled layer IVC. Also common to the two primate groups was a projection from dLGN to layer VI. There was no dLGN projection to any prestriate area in any of the primates. However, after an injection limited to the prestriate cortex of Macaca, light autoradiographic labeling was seen in the interlaminar zones and the magnocellular and S laminae, demonstrating a prestriate-dLGN pathway. Our results indicate that the primate visual system differs significantly from the cat in having no dLGN projection to area 18. There are also signficant differences between primates in the level at which the possibility of binocularity (of an excitatory nature) first occurs in the striate cortex because in the species studied thus far with neuroanatomical methods, Old World primates have ocular dominance columns in layer IV but most New World monkeys lack them.

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Four physiologically identified neurons in the A laminae of the cat’s dorsal lateral geniculate nucleus were filled with horseradish peroxidase and studied using the electron microscope. Two were X-cells and two were Y-cells. Each had electrophysiological properties appropriate for its X- or Y-cell class, and each also had an axon that projected into the optic radiation, indicative of a geniculocortical relay cell. Representative samples from about 10% of each neuron’s entire dendritic arbor (proximal and distal) were taken to obtain an estimate of the types and distributions of synapses contacting these arbors. One X-cell had a cytoplasmic laminar body, but there were no other significant cytological differences seen among the neurons. Common to each of the neurons were the following synaptic features: (i) retinal terminals (r. l. p.) were mostly or entirely restricted to proximal dendrites or dendritic appendages (< 100 μm from the soma). These terminals constituted about 15-25% of the synapses on the proximal dendrites, (ii) Terminals with flattened or pleomorphic synaptic vesicles (f. terminals) were predominant on the proximal dendrites (30-55% of the total synapses for that region) and were mainly located near the retinal terminals. A smaller percentage (10-20%) were also distributed onto the distal dendrites, (iii) Small terminals with round synaptic vesicles (r. s. d.), many presumably having a cortical origin, predominated (60-80%) on distal dendrites (> 100 μm), but also formed a large proportion (40-70%) of the synapses on the intermediate (50-150 μm) dendrites. Total synaptic contacts for one X-cell and one Y-cell were estimated at about 4000 and 5000, respectively. The major fine structural differences observed between X- and Y-cells were almost entirely related to the retinal afferents. First, the retinal synapses for X-cells were mostly made on to dendritic appendages (spines, etc.), whereas Y-cells had most of their retinal synapses onto the shafts of primary and proximal secondary dendrites (that is, near branch points). Second, the retinal terminals that contacted X-cell dendrites nearly always formed triadic arrangements that included nearby f. terminals, but those on Y-cells rarely did so. Finally, the main type of f. terminals associated with X-cells were morphologically different from most of those associated with the Y-cells, and this also related directly to the triadic arrangements; that is, f. terminals in the triadic arrangements were morphologically distinguishable from f. terminals that did not participate in triadic arrangements. Even though the present sample is quite small, these morphological differences between X- and Y-cells indicate that they might be the synaptic basis for some of the differential processing of information occurring for the two cell types in the lateral geniculate nucleus.

25 male rats copulated with 25 estrous females until they reached an arbitrary criterion of sexual exhaustion. At this point replacement of the original female by a new estrous partner sometimes resulted in the resumption of mating activity and the achievement of 1 or more additional ejaculations. Removing and returning the original female had only a slight stimulating effect. Substitution of a female that had recently mated with another male was more likely to evoke renewal of sexual activity. The most effective procedure involved replacement of the original partner by an unmated estrous female.

Four cognitive factors were extracted from test data obtained on 997 families (3,268 individuals) in Hawaii. Factor loading profiles for the two largest ethnic groups (Caucasians and Japanese) are nearly identical, as are profiles for three different age groups. Age curves are presented for factor scores and for four specific cognitive tests. The younger respondents on the age curves are biological offspring of older respondents represented on the same curves, facilitating an unusual control for between-family variance. When the data were stratified by ethnicity, differential rates of cognitive development were indicated.

We introduce ASAP3, a refinement of the batch means algorithms ASAP and ASAP2, that delivers point and confidence-interval estimators for the expected response of a steady-state simulation. ASAP3 is a sequential procedure designed to produce a confidence-interval estimator that satisfies user-specified requirements on absolute or relative precision as well as coverage probability. ASAP3 operates as follows: the batch size is progressively increased until the batch means pass the Shapiro-Wilk test for multivariate normality; and then ASAP3 fits a first-order autoregressive (AR(1)) time series model to the batch means. If necessary, the batch size is further increased until the autoregressive parameter in the AR(1) model does not significantly exceed 0.8. Next, ASAP3 computes the terms of an inverse Cornish-Fisher expansion for the classical batch means t -ratio based on the AR(1) parameter estimates; and finally ASAP3 delivers a correlation-adjusted confidence interval based on this expansion. Regarding not only conformance to the precision and coverage-probability requirements but also the mean and variance of the half-length of the delivered confidence interval, ASAP3 compared favorably to other batch means procedures (namely, ABATCH, ASAP, ASAP2, and LBATCH) in an extensive experimental performance evaluation.

Genetic algorithms (GAs) are very efficient at exploring the entire search space; however, they are relatively poor at finding the precise local optimal solution in the region in which the algorithm converges. Hybrid GAs are the combination of improvement procedures, which are good at finding local optima, and GAs. There are two basic strategies for using hybrid GAs. In the first, Lamarckian learning, the genetic representation is updated to match the solution found by the improvement procedure. In the second, Baldwinian learning, improvement procedures are used to change the fitness landscape, but the solution that is found is not encoded back into the genetic string. This paper examines the issue of using partial Lamarckianism (i.e., the updating of the genetic representation for only a percentage of the individuals), as compared to pure Lamarckian and pure Baldwinian learning in hybrid GAs. Multiple instances of five bounded nonlinear problems, the location-allocation problem, and the cell formation problem were used as test problems in an empirical investigation. Neither a pure Lamarckian nor a pure Baldwinian search strategy was found to consistently lead to quicker convergence of the GA to the best known solution for the series of test problems. Based on a minimax criterion (i.e., minimizing the worst case performance across all test problem instances), the 20% and 40% partial Lamarckianism search strategies yielded the best mixture of solution quality and computational efficiency.