The brain decade in debate: VI. Sensory and motor maps: dynamics and plasticity

This article is an edited transcription of a virtual symposium promoted by the Brazilian Society of Neuroscience and Behavior (SBNeC). Although the dynamics of sensory and motor representations have been one of the most studied features of the central nervous system, the actual mechanisms of brain plasticity that underlie the dynamic nature of sensory and motor maps are not entirely unraveled. Our discussion began with the notion that the processing of sensory information depends on many different cortical areas. Some of them are arranged topographically and others have non-topographic (analytical) properties. Besides a sensory component, every cortical area has an efferent output that can be mapped and can influence motor behavior. Although new behaviors might be related to modifications of the sensory or motor representations in a given cortical area, they can also be the result of the acquired ability to make new associations between specific sensory cues and certain movements, a type of learning known as conditioning motor learning. Many types of learning are directly related to the emotional or cognitive context in which a new behavior is acquired. This has been demonstrated by paradigms in which the receptive field properties of cortical neurons are modified when an animal is engaged in a given discrimination task or when a triggering feature is paired with an aversive stimulus. The role of the cholinergic input from the nucleus basalis to the neocortex was also highlighted as one important component of the circuits responsible for the context-dependent changes that can be induced in cortical maps

NADPH-diaphorase activity in area 17 on the squirrel monkey visual cortex: neuropil pattern, cell morphology and laminar distribution

We studied the distribution of NADPH-diaphorase activity in the visual cortex of normal adult New World monkeys (Saimiri sciureus) using the malic enzyme "indirect" method. NADPH-diaphorase neuropil activity had a heterogeneous distribution. In coronal sections, it had a clear laminar pattern that was coincident with Nissl-stained layers. In tangential sections, we observed blobs in supragranular layers of V1 and stripes throughout the entire V2. We quantified and compared the tangential distribution of NADPH-diaphorase and cytochrome oxidade blobs in adjacent sections of the supragramular layers of V1. Although their spatial distributions were rather similar, the two enzymes did not always overlap. The histochemical reaction also revealed two different types of stained cells: a slightly stained subpopulation and a subgroup of deeply stained neurons resembling a Golgi impregnation. These neurons were sparsely spined non-pyramidal cells. Their dendritic arbors were very well stained but their axons were not always evident. In the gray matter, heavily stained neurons showed different dendritic arbor morphologies. However, most of the strongly reactive cells lay in the subjacent white matter, where they presented a more homogenous morphology. Our results demonstrate that the pattern of NADPH-diaphorase activity is similar to that previously described in Old World monkeys.

NADPH diaphorase histochemistry as a marker for barrels in rat somatosensory cortex

The primary somatosensory area (S1) of rodents presents multicellular units called barrels which can be identified by different techniques (e.g., Nissl staining, cytochrome oxidase or succinate dehydrogenase histochemistry). We applied NADPH diaphorase histochemistry to tangential sections of rat neocortex to determine if the reactive neuropil also shows the same remarkable array observed with other techniques. We demonstrated NADPH diaphorase-positive barrels in all hemispheres tested. The barrels are recognized as patches where the neuropil is most reactive. Each barrel is separated from the other by a less labeled neuropil. Many NADPH diaphorase-positive neurons are seen along the section, but very few cells are found in the barrel fild. In this region, most of the labeled neurons are localized in the less reactive region between the barrels, although a few NADPH diaphorase-positive cells can also be found insede the barrels

Distribution of NADPH-diaphorase-positive neurons in the opossum neocortex

The distribution of NADPH-diaphorase reactive cells was evalutated both in horizontal sections of a flattended cortex and in transversal sections of the opossum (Didelphis marsupialis) neocortex. The tangential distribution of labeled cells behind the orbitalis fissure was denser in the rostral vs caudal regions and in the lateral vs medial regions. Transversal sections revealed that most of the positive neurons are in the grey matter, although 1/4 of this population is located in the underlying white matter. This pattern of neuronal distribution is similar to that previously described in rodents, but quite different from that observed in higher mammals such as the cat and primates

Evidence for recrossing of the pathway from the retina to the ipsilateral nucleus of the optic tract

Single-unit recordings of the nucleous of the optic tract (NOT) under visual stimulation were performed in 5 opossums. Most of the units were directionally selective. Receptive fields for the contralateral eye lie mainly in the contralateral field while those for the ipsilateral eye were mainly in the ipsilateral field. As the nasal does not project ipsilaterally, recrossing must occur in the pathway from the retina to the ipsilateral NOT. Possible sites for this recrossing are discussed

Unidade de recem-nascidos externos: descricao da clientela internada no periodo de janeiro de 1977 a marco de 1978. / External newborn infants units: description of the patients admitted in the period from january 1977 to march 1978

Os autores apresentam os resultados do estudo medico-social de 351 recem-nascidos admitidos na Unidade de Recem-nascidos Externos do Instituto da Crianca "Prof. Pedro de Alcantara" do Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo, de janeiro de 1977 a marco de 1978. Destacam-se os comentarios feitos a proposito de: 1. idade dos pacientes; 2.diagnostico de admissao; 3. idade dos pais; 4. seguimento pre-natal; 5. tipo de aleitamento e 6. procedencia

Projeto de saude comunitaria do Instituto da Crianca. / Communitary health project of the Instituto da Crianca

Os autores apresentam os dados de caracterizacao socio-economica e algumas informacoes sobre morbidade da populacao residente na area do "Projeto Piloto" de Saude Comunitaria do Instituto da Crianca. A analise dos dados evidencia a importancia de atuar sobre as necessidades sentidas e as condicoes de vida da populacao e nao apenas desenvolver um trabalho de assistencia a saude, visando obter resultados mais concretos e duradouros