Study on suppression of otoacoustic emissions: lateral domain

A pon stimulation by contralateral, ipsilateral or bilateral noise, the medial olivocochlear efferent tract changes the amplitude of otoacoustic emissions relative to the tested ear, reducing or removing it; this resulted in a reduction/suppression effect of otoacoustic emissions. Differences in patterns of elimination/reduction of otoacoustic emissions between ears have been documented worldwide; there are, however, no Brazilian studies investigating the effect of lateral dominance.Aims: To compare the effect of the presence of deletion/reduction of otoacoustic emissions and their amplitude relative to lateral dominance in normal hearing adults.Methods: A clinical and experimental study. The sample comprised 75 individuals. The methodology was conventional - linear click intensity of 60 dB SPL; white noise was contralateral stimulation at 60 dB SPL.Description of results: There were no statistically significant differences between right and left ear results, in terms of asymmetry of the degree of otoacoustic emissions and the presence of suppression/reduction.Conclusion: There is no lateral dominance in the degree of otoacoustic emissions in the presence of suppression/reduction in the study population.

Prevalência do lado preferencial mastigatório e sua relação com a alimentação, a saúde periodontal, o lado preferencial no primeiro ciclo mastigatório e a dominância lateral nas dentições decídua, mista e permanente

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

An analysis of bimanual actions in natural feeding of semi-wild chimpanzees

Objective The objective of the current study was to investigate the lateral dominance for a bimanually coordinated natural feeding behavior in semi-wild chimpanzees. Materials and Methods We investigated strychnos spp. fruit consumption behaviors in semi-wild chimpanzees as an ecologically comparable feeding behavior to those found in cerebral lateralization studies of non-primate species. Video recordings of thirty-three chimpanzees were assessed while they consumed hard-shelled strychnos fruits. We explored statistical and descriptive measures of hand dominance to highlight lateralized patterns. Results Statistical evaluation of feeding bouts revealed a group-level right-handed bias for bimanual coordinated feeding actions, however few individuals were statistically lateralized. Descriptive analyses revealed that the majority of individuals were lateralized and possessed a right-handed bias for strychnos feeding behavior. Discussion The results provide empirical evidence in supports of an early evolutionary delineation of function for the right and left hemispheres. The present findings suggest that great apes express an intermediate stage along the phylogenetic trajectory of human manual lateralization.

Estudio de la relación e influencia de varios aspectos psicológicos en el aprendizaje lector.

Estudiar la influencia que tienen en el aprendizaje de la lectura aspectos psicológicos como: inteligencia, orientación espacial, percepción visual, lateralidad, ritmo, memoria y vocabulario. 4 grupos de 100 sujetos de 7 a 10 años. Introduce el tema de la dislexia y de los factores psicológicos que influyen en el aprendizaje lector. Elige la muestra. Pasa las pruebas de inteligencia, orientación espacial, percepción visual, lateralidad, estructuración espacio-temporal, memoria, vocabulario y lectura. Relaciona la lectura con los aspectos anteriores. Test PMC de Raven. Adaptación de la prueba de Picq-Vayer. Adaptación de Hilda Santucci y Marie Germaine Petreux de la prueba de L. Bender. Pruebas de Harris. Test of Lateral Dominance. Test figura completa de Rey. Test WISC. Índices estadísticos. Varios aspectos relacionados con el tiempo lector y la correción lectora dan correlaciones parciales significativas a nivel de confianza de 99 por ciento. La lateralidad suele dar correlación no significativa. Cuanto más mayores son los sujetos, van apareciendo otros aspectos psicológicos, físicos, sociológicos, que influyen con más fuerza sobre el aprendizaje lector. Tiempo, corrección, estructuración espacio-temporal y vocabulario, forman conjuntamente la base del aprendizaje lector.

Especialização hemisférica e assimetrias comportamentais: o lado da cama tem gênero?

Data relative on the side occupied by females in double beds were collected in order to evaluate the feasebility to carryout a more extensive study to determine if this behavioral pattern is lateralized. Information relative to the side occupied in the bed, manual lateralization, how long lived togheter, and other related questions were collected in a sample of 229 women aged from 20 to 65 years old. Total frequencies of the bed side occupied showed to be equivalent, however, the left side showed to be chosen significantly more (70%)(χ2 = 5.4; 1 d.f.; p<0.05) when the choice was stated to be spontaneous (i.e, not determined by an impositive factor) . It is concluded that the obtained data give favourable support to an extensive study on the subject, which inserts into the area of research devoted to the understanding of the functional characteristics of central nervous functioning.

The apical control of lateral bud development in excised shoot tips of Cuscuta reflexa cultured in vitro

Excised shoot tips of Cuscuta reflexa Roxb. (dodder), a rootless and leafless angiospermic plant parasite, were cultured in vitro for the study of the control of lateral bud development by the apex. In a chemically defined medium lacking hormones, the basal bud alone developed into a shoot. The addition of coconut milk to the growth medium induced the activation of multiple lateral buds, but only a single bud developed further into a shoot. The decapitation of this shoot induced the development of another shoot and the process could be repeated. This showed the controlling effect of the apex in correlative control of bud development. Application of indole-3-acetic acid to the shoot tip explant delayed the development of the lateral bud. Gibberellic acid A3 induced a marked elongation growth of the explant and reinforced apical dominance. The direct application of cytokinin to an inhibited bud relieved it from apical dominance. A basipetally decreasing concentration gradient of auxin may prevail at the nodes. Bud outgrowth is probably stimulated by cytokinin produced locally in the bud.

Automatic attention lateral asymmetry in visual discrimination tasks

There is evidence that automatic visual attention favors the right side. This study investigated whether this lateral asymmetry interacts with the right hemisphere dominance for visual location processing and left hemisphere dominance for visual shape processing. Volunteers were tested in a location discrimination task and a shape discrimination task. The target stimuli (S2) could occur in the left or right hemifield. They were preceded by an ipsilateral, contralateral or bilateral prime stimulus (S1). The attentional effect produced by the right S1 was larger than that produced by the left S1. This lateral asymmetry was similar between the two tasks suggesting that the hemispheric asymmetries of visual mechanisms do not contribute to it. The finding that it was basically due to a longer reaction time to the left S2 than to the right S2 for the contralateral S1 condition suggests that the inhibitory component of attention is laterally asymmetric.

Zooplankton composition, dominance and abundance as indicators of environmental compartmentalization in Jurumirim Reservoir (Paranapanema River), São Paulo, Brazil

Spatial and temporal patterns in the distribution of the zooplankton in a large tropical reservoir were investigated for a year. The zooplankton was sampled at 10 limnetic stations. Rotifera were richest in number of species and individuals, especially in transitional river-lake zones. They were dominant during the summer in nine sampling stations, and decreased in spring. The main species were Polyarthra vulgaris, Keratella americana, K. cochlearis and Conochilus unicornis. Polyarthra vulgaris was widely distributed. Keratella was more abundant at upstream stations, and a dense population of C. unicornis was observed in a lateral, sheltered compartment. Among copepods, Calanoida were more abundant in spring and Cyclopoida in autumn. Longitudinal gradients in the Calanoida/Cyclopoida relation were observed, with the predominance of Cyclopoida at upstream sampling stations and Calanoida in more lacustrine zones towards the dam. Notodiaptomus iheringi, Thermocyclops minutus and T. decipiens were the main species. Diaphanosoma birgei, the most abundant cladoceran, mainly occurred in lacustrine zones, while Moina minuta was more abundant at riverine sampling stations, generally in association with Bosminopsis deitersi. Peaks of tintinnid protozoans were observed in upstream zones during summer and spring.

A model of ocular dominance column development by competition for trophic factor

Recent experimental evidence has shown that application of certain neurotrophic factors (NTs) to the developing primary visual cortex prevents the development of ocular dominance (OD) columns. One interpretation of this result is that afferents from the lateral geniculate nucleus compete for postsynaptic trophic factor in an activity-dependent manner. Application of excess trophic factor eliminates this competition, thereby preventing OD column formation. We present a model of OD column development, incorporating Hebbian synaptic modification and activity-driven competition for NT, which accounts for both normal OD column development as well as the prevention of that development when competition is removed. In the “control” situation, when available NT is below a critical amount, OD columns form normally. These columns form without weight normalization procedures and in the presence of positive inter-eye correlations. In the “experimental” case, OD column development is prevented in a local neighborhood in which excess NT has been added. Our model proposes a biologically plausible mechanism for competition between neural populations that is motivated by several pieces of experimental data, thereby accounting for both normal and experimentally perturbed conditions.