Pulsiones del espacio : Oteiza y la aproximación a la arquitectura como vacío activo

Este trabajo se centra en el estudio de las investigaciones de Jorge Oteiza en torno a la funcionalidad estética del espacio, en especial, en la actividad artística que desarrolló en el año 1958, un año decisivo en la vida del escultor en el que dio por finalizado su proceso de experimentación sobre la naturaleza espacial de la estatua. En este desenlace tuvo un papel fundamental la relación funcional que planteó, a la hora de retomar su trabajo después de su triunfo en la IV Bienal de São Paulo de 1957, entre la escultura y la arquitectura. La primera, entendida como organismo puramente espacial, debía de responder a las condiciones de su mundo circundante, el espacio arquitectónico. Su función: acondicionarlo estéticamente para satisfacer las necesidades espirituales del habitante. Siguiendo el canon estético que para la escultura acababa de anunciar en Brasil, la desocupación espacial (la liberación de la energía espacial de la estatua, el rompimiento de la neutralidad del espacio libre) no se trataba de embellecer superficialmente la arquitectura sino de activar su vacío interior. Oteiza, que siempre estuvo muy interesado por la arquitectura y que había colaborado con anterioridad en numerosas ocasiones con los mejores arquitectos del país, fue durante este año cuando profundizó de manera más sistemática (teórica y prácticamente) sobre la relación arte-arquitectura. De hecho, él mismo nombraba como el último trabajo de su línea de experimentación en escultura a su propuesta para el concurso del Monumento a José Batlle en Montevideo, que junto al arquitecto Roberto Puig acabaron a finales de año. En el proyecto se planteaba a escala urbana, y como ejemplo concreto, el modelo teórico de integración arquitectura + (arte=0) que había elaborado los meses anteriores, la integración vacía. En el texto explicativo que acompañaba al proyecto (un texto que desbordaba los límites de una memoria al uso) demandaba la necesidad de la toma de conciencia estética del espacio, como acto de libertad individual, y declaraba el fin del rol de espectador del hombre frente a la obra de arte, reclamando su participación activa en la misma. Para él, la noción del espacio estético no era una condición innata en el hombre, se descubría, se aprendía, evolucionaba y se olvidaba (una vez convertido en hábito). Frente a la ceguera de la sensibilidad espacial del hombre, proponía la educación de la percepción espacial, condicionar emocionalmente la reflexión espontánea ante el juego espacial de las formas en la naturaleza y el espectáculo natural de la ciudad. Aprender a leer el lenguaje emocional del espacio, a pensar visualmente. La obra de arte era así un catalizador espiritual del contorno del mundo, modificador de la vida espacial circundante que corregía hábitos visuales y condicionaba estímulos y reflejos. Desde una resonancia afectiva con la definición psicológica del término (como energía psíquica profunda que invita o incita a pasar a la acción), a diferencia del instinto, la pulsión (siendo la fuente de toda conducta espontánea) es susceptible de ser modificada por la experiencia, por la educación, por la cultura, por el deseo. Es desde esta aproximación en términos de energía desde la que se propone la noción pulsiones del espacio como fórmula (reversible) entre la energía espacial liberada en el proceso de desocupación definido por Oteiza y caracterizadora de la obra como vacío activo (en escultura, en arquitectura), y la energía psíquica profunda que invita o incita a la toma de posesión del espacio (la voluntad espacial absoluta con la que Oteiza definía su modelo de arte=0, cero como expresión formal). Si el hombre modifica su entorno al mismo tiempo que es condicionado por él, es indispensable una conciencia estética del espacio que le enseñe, de entre todas las posibilidades que este le ofrece, qué es lo que necesita (qué es lo que le falta), para tomar posesión de él, para un efectivo ser o existir en el espacio. Es desde esta caracterización como energía por lo que las pulsiones del espacio se sitúan entre el hombre y su entorno (construido) y permiten la transformación entre energía espacial y energía psíquica; entre su hábitat y sus hábitos. Por estas mismas fechas, Oteiza definía una casa como un conjunto articulado de vacíos activos, como una obra de plástica pura que no es arte sino en función del habitante. Es este habitante, educado en la toma de conciencia estética del espacio, el que participando activamente en la interpretación de los espacios previstos por el arquitecto, sintiendo y movido por las pulsiones del espacio, hará uso adecuado de la arquitectura; pasando de un arte como objeto a un arte como comportamiento, transformará su habitar en un arte, el arte de habitar. ABSTRACT This work focuses on the study of Jorge Oteiza’s investigations on the aesthetic functionality of space, especially on his artistic activity developed in 1958, a decisive year in the life of the sculptor, in which he gave end to his process of experimentation on the spatial nature of the statue. In this outcome it was fundamental the functional relationship that he propounded, at the time of returning to work after his triumph in the IV Bienal de São Paulo in 1957, between sculpture and architecture. The first, understood as a purely spatial organism, should respond to the conditions of its environment (umwelt), the architectonic space. Its function: set it up aesthetically to meet the spiritual needs of the inhabitant. Following the aesthetic canon that he had just announced in Brazil for sculpture, the spatial disoccupation (the liberation of the spatial energy of the statue, the breaking of the neutrality of the free space) the aim was not to superficially beautify architecture but to activate its inner void. Oteiza, who had always been very interested in architecture and who had previously collaborated on numerous occasions with the best architects in the country, was in this year when he deepened in a more systematic way (theoretically and practically) about the art-architecture relationship. In fact, he named as the last work of his line of experimentation in sculpture to his proposal for the competition of the Monument to José Batlle in Montevideo, which, developed together with the architect Roberto Puig, was ended at the end of the year. The project proposed on an urban scale, and as a concrete example, the theoretical model of integration architecture + (art = 0) which he had elaborated the previous months, the empty integration. In the explanatory text accompanying the project (a text that exceeded the normal extents of a competition statement) he demanded the need of the aesthetic awareness of space, as an act of individual freedom, and it declared the end of the role of man as passive spectator in front of the work of art, claiming his actively participation in it. For him, the notion of the aesthetic space was not an inborn condition in man; first it was discovered, then learned, evolved and finally forgotten (once converted into a habit). To counteract blindness of the spatial sensitivity of man, he proposed the education of spatial perception, to emotionally influence the spontaneous reflection in front of the spatial game of forms in nature and the natural spectacle of the city. Learn to read the emotional language of space, to think visually. The work of art was thus a spiritual catalyst of the world’s contour, a modifier of the surrounding spatial life that corrected visual habits and conditioned stimuli and reflexes. From an emotional resonance with the psychological definition of the term (such as deep psychic power that invites or urges action), as opposed to instinct, drive (being the source of all spontaneous behavior) is likely to be modified by experience, by education, by culture, by desire. It is from this approach in terms of energy from which the notion drives of space is proposed, as a (reversible) formula between the spatial energy released in the process of disoccupation defined by Oteiza and characterizing of the work as a charged void (in sculpture, in architecture), and the deep psychic energy that invites or encourages the taking possession of the space (the absolute spatial will with which Oteiza defined its model of Art = 0, zero as a formal expression). If man changes his environment at the same time that is conditioned by it, it is essential an aesthetic awareness of space that shows him, among all the possibilities that it offers, what he needs (what is what he lacks), in order to take possession of it, for an effective being or existing in space. It is this characterization as energy by what drives of space lie between man and his (built) environment and allow the transformation between spatial and psychological energy; between his habitat and his habits. Around this same time, Oteiza defined a House as an articulated set of charged voids, as a work of pure plastic that is not art but according to the inhabitant. It is this inhabitant, educated in aesthetic awareness of space, who actively participating in the interpretation of the spaces provided by the architect, feeling and moved by the drives of the space, will make proper use of the architecture; from an art as object to an art as behavior, he will transform his inhabitation into an art, the art of inhabitation.

Functional organization of spatial and nonspatial working memory processing within the human lateral frontal cortex

The present study used functional magnetic resonance imaging to demonstrate that performance of visual spatial and visual nonspatial working memory tasks involve the same regions of the lateral prefrontal cortex when all factors unrelated to the type of stimulus material are appropriately controlled. These results provide evidence that spatial and nonspatial working memory may not be mediated, respectively, by mid-dorsolateral and mid-ventrolateral regions of the frontal lobe, as widely assumed, and support the alternative notion that specific regions of the lateral prefrontal cortex make identical executive functional contributions to both spatial and nonspatial working memory.

Bidirectional, experience-dependent regulation of N-methyl-d-aspartate receptor subunit composition in the rat visual cortex during postnatal development

In the visual cortex, as elsewhere, N-methyl-d-aspartate receptors (NMDARs) play a critical role in triggering long-term, experience-dependent synaptic plasticity. Modifications of NMDAR subunit composition alter receptor function, and could have a large impact on the properties of synaptic plasticity. We have used immunoblot analysis to investigate the effects of age and visual experience on the expression of different NMDAR subunits in synaptoneurosomes prepared from rat visual cortices. NMDARs at birth are comprised of NR2B and NR1 subunits, and, over the first 5 postnatal weeks, there is a progressive inclusion of the NR2A subunit. Dark rearing from birth attenuates the developmental increase in NR2A. Levels of NR2A increase rapidly (in <2 hr) when dark-reared animals are exposed to light, and decrease gradually over the course of 3 to 4 days when animals are deprived of light. These data reveal that NMDAR subunit composition in the visual cortex is remarkably dynamic and bidirectionally regulated by sensory experience. We propose that NMDAR subunit regulation is a mechanism for experience-dependent modulation of synaptic plasticity in the visual cortex, and serves to maintain synaptic strength within an optimal dynamic range.

Visual stimuli induce waves of electrical activity in turtle cortex

The computations involved in the processing of a visual scene invariably involve the interactions among neurons throughout all of visual cortex. One hypothesis is that the timing of neuronal activity, as well as the amplitude of activity, provides a means to encode features of objects. The experimental data from studies on cat [Gray, C. M., Konig, P., Engel, A. K. & Singer, W. (1989) Nature (London) 338, 334–337] support a view in which only synchronous (no phase lags) activity carries information about the visual scene. In contrast, theoretical studies suggest, on the one hand, the utility of multiple phases within a population of neurons as a means to encode independent visual features and, on the other hand, the likely existence of timing differences solely on the basis of network dynamics. Here we use widefield imaging in conjunction with voltage-sensitive dyes to record electrical activity from the virtually intact, unanesthetized turtle brain. Our data consist of single-trial measurements. We analyze our data in the frequency domain to isolate coherent events that lie in different frequency bands. Low frequency oscillations (<5 Hz) are seen in both ongoing activity and activity induced by visual stimuli. These oscillations propagate parallel to the afferent input. Higher frequency activity, with spectral peaks near 10 and 20 Hz, is seen solely in response to stimulation. This activity consists of plane waves and spiral-like waves, as well as more complex patterns. The plane waves have an average phase gradient of ≈π/2 radians/mm and propagate orthogonally to the low frequency waves. Our results show that large-scale differences in neuronal timing are present and persistent during visual processing.

Brain activity in visual cortex predicts individual differences in reading performance

The relationship between brain activity and reading performance was examined to test the hypothesis that dyslexia involves a deficit in a specific visual pathway known as the magnocellular (M) pathway. Functional magnetic resonance imaging was used to measure brain activity in dyslexic and control subjects in conditions designed to preferentially stimulate the M pathway. Dyslexics showed reduced activity compared with controls both in the primary visual cortex and in a secondary cortical visual area (MT+) that is believed to receive a strong M pathway input. Most importantly, significant correlations were found between individual differences in reading rate and brain activity. These results support the hypothesis for an M pathway abnormality in dyslexia and imply a strong relationship between the integrity of the M pathway and reading ability.

Perceptual learning reflects external noise filtering and internal noise reduction through channel reweighting

To investigate the nature of plasticity in the adult visual system, perceptual learning was measured in a peripheral orientation discrimination task with systematically varying amounts of external (environmental) noise. The signal contrasts required to achieve threshold were reduced by a factor or two or more after training at all levels of external noise. The strong quantitative regularities revealed by this novel paradigm ruled out changes in multiplicative internal noise, changes in transducer nonlinearites, and simple attentional tradeoffs. Instead, the regularities specify the mechanisms of perceptual learning at the behavioral level as a combination of external noise exclusion and stimulus enhancement via additive internal noise reduction. The findings also constrain the neural architecture of perceptual learning. Plasticity in the weights between basic visual channels and decision is sufficient to account for perceptual learning without requiring the retuning of visual mechanisms.

The interphotoreceptor retinoid binding protein gene in therian mammals: Implications for higher level relationships and evidence for loss of function in the marsupial mole

The subclass Theria of Mammalia includes marsupials (infraclass Metatheria) and placentals (infraclass Eutheria). Within each group, interordinal relationships remain unclear. One limitation of many studies is incomplete ordinal representation. Here, we analyze DNA sequences for part of exon 1 of the interphotoreceptor retinoid binding protein gene, including 10 that are newly reported, for representatives of all therian orders. Among placentals, the most robust clades are Cetartiodactyla, Paenungulata, and an expanded African clade that includes paenungulates, tubulidentates, and macroscelideans. Anagalida, Archonta, Altungulata, Hyracoidea + Perissodactyla, Ungulata, and the “flying primate” hypothesis are rejected by statistical tests. Among marsupials, the most robust clade includes all orders except Didelphimorphia. The phylogenetic placement of the monito del monte and the marsupial mole remains unclear. However, the marsupial mole sequence contains three frameshift indels and numerous stop codons in all three reading frames. Given that the interphotoreceptor retinoid binding protein gene is a single-copy gene that functions in the visual cycle and that the marsupial mole is blind with degenerate eyes, this finding suggests that phenotypic degeneration of the eyes is accompanied by parallel changes at the molecular level as a result of relaxed selective constraints.

Neural fate of seen and unseen faces in visuospatial neglect: A combined event-related functional MRI and event-related potential study

To compare neural activity produced by visual events that escape or reach conscious awareness, we used event-related MRI and evoked potentials in a patient who had neglect and extinction after focal right parietal damage, but intact visual fields. This neurological disorder entails a loss of awareness for stimuli in the field contralateral to a brain lesion when stimuli are simultaneously presented on the ipsilateral side, even though early visual areas may be intact, and single contralateral stimuli may still be perceived. Functional MRI and event-related potential study were performed during a task where faces or shapes appeared in the right, left, or both fields. Unilateral stimuli produced normal responses in V1 and extrastriate areas. In bilateral events, left faces that were not perceived still activated right V1 and inferior temporal cortex and evoked nonsignificantly reduced N1 potentials, with preserved face-specific negative potentials at 170 ms. When left faces were perceived, the same stimuli produced greater activity in a distributed network of areas including right V1 and cuneus, bilateral fusiform gyri, and left parietal cortex. Also, effective connectivity between visual, parietal, and frontal areas increased during perception of faces. These results suggest that activity can occur in V1 and ventral temporal cortex without awareness, whereas coupling with dorsal parietal and frontal areas may be critical for such activity to afford conscious perception.

A neural system for human visual working memory

Working memory is the process of actively maintaining a representation of information for a brief period of time so that it is available for use. In monkeys, visual working memory involves the concerted activity of a distributed neural system, including posterior areas in visual cortex and anterior areas in prefrontal cortex. Within visual cortex, ventral stream areas are selectively involved in object vision, whereas dorsal stream areas are selectively involved in spatial vision. This domain specificity appears to extend forward into prefrontal cortex, with ventrolateral areas involved mainly in working memory for objects and dorsolateral areas involved mainly in working memory for spatial locations. The organization of this distributed neural system for working memory in monkeys appears to be conserved in humans, though some differences between the two species exist. In humans, as compared with monkeys, areas specialized for object vision in the ventral stream have a more inferior location in temporal cortex, whereas areas specialized for spatial vision in the dorsal stream have a more superior location in parietal cortex. Displacement of both sets of visual areas away from the posterior perisylvian cortex may be related to the emergence of language over the course of brain evolution. Whereas areas specialized for object working memory in humans and monkeys are similarly located in ventrolateral prefrontal cortex, those specialized for spatial working memory occupy a more superior and posterior location within dorsal prefrontal cortex in humans than in monkeys. As in posterior cortex, this displacement in frontal cortex also may be related to the emergence of new areas to serve distinctively human cognitive abilities.

Cerebral organization for language in deaf and hearing subjects: Biological constraints and effects of experience

Cerebral organization during sentence processing in English and in American Sign Language (ASL) was characterized by employing functional magnetic resonance imaging (fMRI) at 4 T. Effects of deafness, age of language acquisition, and bilingualism were assessed by comparing results from (i) normally hearing, monolingual, native speakers of English, (ii) congenitally, genetically deaf, native signers of ASL who learned English late and through the visual modality, and (iii) normally hearing bilinguals who were native signers of ASL and speakers of English. All groups, hearing and deaf, processing their native language, English or ASL, displayed strong and repeated activation within classical language areas of the left hemisphere. Deaf subjects reading English did not display activation in these regions. These results suggest that the early acquisition of a natural language is important in the expression of the strong bias for these areas to mediate language, independently of the form of the language. In addition, native signers, hearing and deaf, displayed extensive activation of homologous areas within the right hemisphere, indicating that the specific processing requirements of the language also in part determine the organization of the language systems of the brain.

Blood flow and oxygen delivery to human brain during functional activity: Theoretical modeling and experimental data

Coupling of cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) in physiologically activated brain states remains the subject of debates. Recently it was suggested that CBF is tightly coupled to oxidative metabolism in a nonlinear fashion. As part of this hypothesis, mathematical models of oxygen delivery to the brain have been described in which disproportionately large increases in CBF are necessary to sustain even small increases in CMRO2 during activation. We have explored the coupling of CBF and oxygen delivery by using two complementary methods. First, a more complex mathematical model was tested that differs from those recently described in that no assumptions were made regarding tissue oxygen level. Second, [15O] water CBF positron emission tomography (PET) studies in nine healthy subjects were conducted during states of visual activation and hypoxia to examine the relationship of CBF and oxygen delivery. In contrast to previous reports, our model showed adequate tissue levels of oxygen could be maintained without the need for increased CBF or oxygen delivery. Similarly, the PET studies demonstrated that the regional increase in CBF during visual activation was not affected by hypoxia. These findings strongly indicate that the increase in CBF associated with physiological activation is regulated by factors other than local requirements in oxygen.

Irreversibility of cellular aging and neoplastic transformation: a clonal analysis.

Prolonged incubation of NIH 3T3 cells under the growth constraint of confluence results in a persistent impairment of proliferation when the cells are subcultured at low density and a greatly increased probability of neoplastic transformation in assays for transformation. These properties, along with the large accumulation of age pigment bodies in the confluent cells, are cardinal cellular characteristics of aging in organisms and validate the system as a model of cellular aging. Two cultures labeled alpha and beta were obtained after prolonged confluence; both were dominated by cells that were both slowed in growth at low population density and enhanced in growth capacity at high density, a marker of neoplastic transformation. An experiment was designed to study the reversibility of these age-related properties by serial subculture at low density of the two uncloned cultures and their progeny clones derived from assuredly single cells. Both uncloned cultures had many transformed cells and a reduced growth rate on subculture. Serial subculture resulted in a gradual increase in growth rates of both populations, but a reversal of transformation only in the alpha population. The clones originating from both populations varied in the degree of growth impairment and neoplastic transformation. None of the alpha clones increased in growth rate on low density passage nor did the transformed clones among them revert to normal growth behavior. The fastest growing beta clone was originally slower than the control clone, but caught up to it after four weekly subcultures. The other beta clones retained their reduced growth rates. Four of the five beta clones, including the fastest grower, were transformed, and none reverted on subculture. We conclude that the apparent reversal of impaired growth and transformation in the uncloned parental alpha population resulted from the selective growth at low density of fast growing nontransformed clones. The reversal of impaired growth in the uncloned parental beta population was also the result of selective growth of fast growing clones, but in this case they were highly transformed so no apparent reversal of transformation occurred. The clonal results indicate that neither the impaired growth nor the neoplastic transformation found in aging cells is reversible. We discuss the possible contribution of epigenetic and genetic processes to these irreversible changes.

Long-term modifications of synaptic efficacy in the human inferior and middle temporal cortex.

The primate temporal cortex has been demonstrated to play an important role in visual memory and pattern recognition. It is of particular interest to investigate whether activity-dependent modification of synaptic efficacy, a presumptive mechanism for learning and memory, is present in this cortical region. Here we address this issue by examining the induction of synaptic plasticity in surgically resected human inferior and middle temporal cortex. The results show that synaptic strength in the human temporal cortex could undergo bidirectional modifications, depending on the pattern of conditioning stimulation. High frequency stimulation (100 or 40 Hz) in layer IV induced long-term potentiation (LTP) of both intracellular excitatory postsynaptic potentials and evoked field potentials in layers II/III. The LTP induced by 100 Hz tetanus was blocked by 50-100 microM DL-2-amino-5-phosphonovaleric acid, suggesting that N-methyl-D-aspartate receptors were responsible for its induction. Long-term depression (LTD) was elicited by prolonged low frequency stimulation (1 Hz, 15 min). It was reduced, but not completely blocked, by DL-2-amino-5-phosphonovaleric acid, implying that some other mechanisms in addition to N-methyl-DL-aspartate receptors were involved in LTD induction. LTD was input-specific, i.e., low frequency stimulation of one pathway produced LTD of synaptic transmission in that pathway only. Finally, the LTP and LTD could reverse each other, suggesting that they can act cooperatively to modify the functional state of cortical network. These results suggest that LTP and LTD are possible mechanisms for the visual memory and pattern recognition functions performed in the human temporal cortex.

Spatial integration and cortical dynamics.

Cells in adult primary visual cortex are capable of integrating information over much larger portions of the visual field than was originally thought. Moreover, their receptive field properties can be altered by the context within which local features are presented and by changes in visual experience. The substrate for both spatial integration and cortical plasticity is likely to be found in a plexus of long-range horizontal connections, formed by cortical pyramidal cells, which link cells within each cortical area over distances of 6-8 mm. The relationship between horizontal connections and cortical functional architecture suggests a role in visual segmentation and spatial integration. The distribution of lateral interactions within striate cortex was visualized with optical recording, and their functional consequences were explored by using comparable stimuli in human psychophysical experiments and in recordings from alert monkeys. They may represent the substrate for perceptual phenomena such as illusory contours, surface fill-in, and contour saliency. The dynamic nature of receptive field properties and cortical architecture has been seen over time scales ranging from seconds to months. One can induce a remapping of the topography of visual cortex by making focal binocular retinal lesions. Shorter-term plasticity of cortical receptive fields was observed following brief periods of visual stimulation. The mechanisms involved entailed, for the short-term changes, altering the effectiveness of existing cortical connections, and for the long-term changes, sprouting of axon collaterals and synaptogenesis. The mutability of cortical function implies a continual process of calibration and normalization of the perception of visual attributes that is dependent on sensory experience throughout adulthood and might further represent the mechanism of perceptual learning.

Spatial heterogeneity of inhibitory surrounds in the middle temporal visual area.

A recurrent theme in the organization of vertebrate visual cortex is that of receptive fields with an associated "silent" opponency component. In the middle temporal area (area MT), a cortical visual area involved in the analysis of retinal motion in primates, this opponency appears in the form of a region outside the classical receptive field (CRF) that in itself gives no response but suppresses responses to motion evoked within the CRF. This antagonistic motion surround has been described as very large and symmetrically arrayed around the CRF. On the basis of this view, the primary function of the surround has long been thought to consist of simple figure-ground segregation based on movement. We have made use of small stimulus patches to map the form and extent of the surround and find evidence that the surround inhibition of many MT cells is in fact confined to restricted regions on one side or on opposite sides of the CRF. Such regions endow MT cells with the ability to make local-to-local motion comparisons, capable of extracting more complex features from the visual environment, and as such, may be better viewed as intrinsic parts of the receptive field, rather than as separate entities responsible for local-to-global comparisons.