Visual instruction of the neural map of auditory space in the developing optic tectum

Neural maps of visual and auditory space are aligned in the adult optic tectum. In barn owls, this alignment of sensory maps was found to be controlled during ontogeny by visual instruction of the auditory spatial tuning of neurons. Large adaptive changes in auditory spatial tuning were induced by raising owls with displacing prisms mounted in spectacle frames in front of the eyes; neurons became tuned to sound source locations corresponding to their optically displaced, rather than their normal, visual receptive field locations. The results demonstrate that visual experience during development calibrates the tectal auditory space map in a site-specific manner, dictating its topography and alignment with the visual space map.     

Gated visual input to the central auditory system

The central auditory system translates sound localization cues into a map of space guided, in part, by visual experience. In barn owls, this process takes place in the external nucleus of the inferior colliculus (ICX). However, to date, no trace of visual activity has been observed in this auditory nucleus. Here we show that strong visual responses, which are appropriate to guide auditory plasticity, appear in the ICX when inhibition is blocked in the optic tectum. Thus, visual spatial information is gated into the auditory system by an inhibitory mechanism that operates at a higher level in the brain.     

Adaptation to displaced vision: visual,motor, or proprioceptive change?

After seeing his hand through wedge prisms, a subject points incorrectly with that hand at auditory as well as visual targets. The other hand is virtually unaffected. Thus the change cannot be solely visuo-motor or visual. Other evidence suggests that it is a change in felt hand location, rather than motor learning. When the subject's adapted hand feels as if it is pointing straight ahead, for example, it is actually pointing off to one side.     

Space perception in early infancy: perception within a common auditory-visual space

Infants as young as 30 days become visibly distressed upon observing their mothers speak to them while the mother's voice is displaced in space. Their ability to perceive this discrepancy indicates that infant perception occurs within a space that is common to the visual and auditory modes.     

Visual and auditory information processing in children and adults

Children of three ages were compared with adults in a recognition experiment requiring continuous processing of information. The growth in precision for visually presented words is steeper than for auditorially presented words, largely because the former are harder for the first graders and, to a lesser extent, for the third graders. In adults, visual processing of information is at least as good as auditory. The use of receiver operating characteristic curves in describing the data permit greater precision in estimating the capacity of the individual subjects and are particularly useful since the errors of failure to recognize were different from ordinary errors of false recognition, and they occurred in large numbers.     

A neural map of auditory space in the owl

Auditory units that responded to sound only when it originated from a limited area of space were found in the lateral and anterior portions of the midbrain auditory nucleus of the owl (Tyto alba). The areas of space to which these units responded (their receptive fields) were largely independent of the nature and intensity of the sound stimulus. The units were arranged systematically within the midbrain auditory nucleus according to the relative locations of their receptive fields, thus creating a physiological map of auditory space.     

Development of polysensory responses in association cortex of kitten

Sensory responsiveness of single neurons in posterior association cortex of kittens that were 7 to 50 days old was investigated. The percentage of trimodal cells (that is, cells that respond to visual, auditory, and somesthetic stimulation) increased gradually until day 50, when percentages of trimodally responsive cells approached the adult level. In the youngest kittens, cells were predominantly responsive to only visual stimulation. With maturation, responsiveness to auditory and then to somesthetic stimulation was observed in increasing percentages of cells.     

Auditory pathways to the frontal cortex of the mustache bat, Pteronotus parnellii

In primates, certain areas of the frontal cortex play a role in guiding movements toward visual or auditory objects in space. The projections from auditory centers to the frontal cortex of the bat Pteronotus parnellii were examined because echolocating bats utilize auditory cues to guide their movements in space. An area in the frontal cortex receives a direct projection from a division of the auditory thalamus, the suprageniculate nucleus, which in turn receives input from the anterolateral peri-olivary nucleus, an auditory center in the medulla. This pathway to the frontal cortex bypasses the main auditory centers in the midbrain and cortex and could involve as few as four neurons between the cochlea and the frontal cortex. The auditory cortex is also a major source of input to the frontal cortex. This area of the frontal cortex may link the auditory and motor systems by its projections to the superior colliculus.     

Auditory association cortex lesions impair auditory short-term memory in monkeys

Monkeys that were trained to perform auditory and visual short-term memory tasks (delayed matching-to-sample) received lesions of the auditory association cortex in the superior temporal gyrus. Although visual memory was completely unaffected by the lesions, auditory memory was severely impaired. Despite this impairment, all monkeys could discriminate sounds closer in frequency than those used in the auditory memory task. This result suggests that the superior temporal cortex plays a role in auditory processing and retention similar to the role the inferior temporal cortex plays in visual processing and retention.     

断电法消除管道阴极保护电位IR降的研究

通常采用断电法来消除地表测到的埋到管道阴极保护电位（通电电位）含有的各种IR降，但在某些情况下，得到的断电电位并不等于实际的对地电位，可将这些误差区分为断电法可消除的误差IsR和未被消除的误差Vo。介绍了应用馈电试验曲线计算IsR和Vo的方法，并讨论了介质电阻率和杂散电流对它们的影响。     

Prism adaptation: control of intermanual transfer by distribution of practice

Correction of errors in localizing movements produced by laterally displacing vision by means of wedge prisms has been termed "prism adaptation." Intermanual transfer of prism adaptation from an exposed to an unexposed hand, with subject's head immobilized, has been reported not to occur. However, it was found that a standard learning variable, distribution of practice, controls the occurrence or nonoccurrence of transfer. When practice is massed, there is no transfer of adaptation; when it is spaced, the transfer is extensive. Spacing of practice also influences the amount of aftereffect displayed by the exposed hand.     

Functional mapping of the primate auditory system

Cerebral auditory areas were delineated in the awake, passively listening, rhesus monkey by comparing the rates of glucose utilization in an intact hemisphere and in an acoustically isolated contralateral hemisphere of the same animal. The auditory system defined in this way occupied large portions of cerebral tissue, an extent probably second only to that of the visual system. Cortically, the activated areas included the entire superior temporal gyrus and large portions of the parietal, prefrontal, and limbic lobes. Several auditory areas overlapped with previously identified visual areas, suggesting that the auditory system, like the visual system, contains separate pathways for processing stimulus quality, location, and motion.     

Adaptation and negative aftereffect to lateral optical displacement in newly hatched chicks

Chicks wearing hoods containing 8.5-degree wedge prisms from the day of hatching showed both significant reduction in the average lateral displacement of pecking (adaptation) and significant pecking overcompensation in the direction opposite to the original displacement (negative aftereffect) when matched 0-degree plates were substituted for the prisms on the 8th day.     

Experimentally induced visual projections into auditory thalamus and cortex

Retinal cells have been induced to project into the medial geniculate nucleus, the principal auditory thalamic nucleus, in newborn ferrets by reduction of targets of retinal axons in one hemisphere and creation of alternative terminal space for these fibers in the auditory thalamus. Many cells in the medial geniculate nucleus are then visually driven, have large receptive fields, and receive input from retinal ganglion cells with small somata and slow conduction velocities. Visual cells with long conduction latencies and large contralateral receptive fields can also be recorded in primary auditory cortex. Some visual cells in auditory cortex are direction selective or have oriented receptive fields that resemble those of complex cells in primary visual cortex. Thus, functional visual projections can be routed into nonvisual structures in higher mammals, suggesting that the modality of a sensory thalamic nucleus or cortical area may be specified by its inputs during development.     

Remedial Correction of Yield Map Data

Many yield maps exhibit systematic errors that attenuate the underlying yield variation. Two errors are dealt with in detail in this paper: those that occur when the harvester has a narrow finish to a land and those that occur when the harvester is filling up at the start of a harvest run. The authors propose methods to correct or remove erroneous data by the use of an expert filter, or alternatively use of an interpolation technique called potential mapping.     

Visual and nonvisual auditory systems in mammals. Anatomical evidence indicates two kinds of auditory pathways and suggests two kinds of hearing in mammals

Examination of the structural organization of the auditory system of the brain stem shows that the system is composed of a number of separate ascending pathways. This suggests that there may be at least two auditory systems, analogous to the rod and cone pathways in vision. We examined this possibility by investigating the variation in relative size of the medial and lateral superior olivary nuclei in a number of different mammalian species. The lateral superior olive is present in the hedgehog (an insectivore), cat (acarnivore), and squirrel monkey a(primate), but the medial superior olive is absent in the hedgehog. In a group of animals of the same taxonomic order (rodents) the lateral superior olive was present in all species examined, but the medial superior olive was almost wholly absent in the mouse and very prominent in the chinchilla and guinea pig. The absence of the medial superior olive in some animals is surprising because recent anatomical and physiological work has implicated the nucleus in auditory localization. Because of this implication, the medial and lateral olivary nuclei were examined in three species of bat and one dolphin, all echolocating animals. The medial superior olive was absent in these animals, and the lateral superior olive was prominent. These observations support the idea that the medial and lateral superior olives are nuclei on two different ascending auditory systems. It was also noted that the medial superior olive was always well developed in animals with well-developed eyes, and this suggested that the nucleus is in some way related to the visual system. We examined this idea by studying the relation between the numbers of cells in the medial superior olive and in the nucleus of the 6th cranial nerve (one of the motor nuclei concerned with eye movement) in a number of mammalian species. An approximately linear function was found between the sizes of the 6th nucleus and of the medial superior olive in three primates with cone-cell retinas (squirrel monkey, man, and macaque) and four rodents with rod-cell retinas (mouse, rat, guinea pig, and chinchilla). The cell numbers for the ground squirrel (a rodent with cone-cell retina) fitted an extension of the primate curve, and the cell numbers for the cat (in whose retina rods predominate) fitted an extension of the rodent curve. Thus, it is clear that the medial superior olive is related to the visual system, and that it is present in animals with cone-cell fovea and retina (diurnalanimals) and animals with rod-cell retina (that is, nocturnal animals) having good vision. In nonvisual nocturnal animals the nucleus is small or absent. The medial superior olive is probably not concerned with auditory localization in the psychophysical sense but is probably concerned with the movement of head and eyes in the direction of a sound in space. Localization in the psychophysical sense and fine auditory discrimination probably depend upon the ascending pathway which includes the lateral superior olive.     

Selection of social partners as a function of peer contact during rearing

Three groups of monkeys were raised with different degrees of contact with their peers. The first group was allowed no contact, the second only visual and auditory contact, and the third was allowed complete and normal contact with their peers. Animals of all three groups were allowed to interact socially; they were then tested for their preference for monkeys raised under the same conditions or for monkeys raised under different conditions. Monkeys raised under the same conditions preferred each other, even if the stimulus animals were completely strange to the test monkey.     

Superior colliculus: some receptive field properties of bimodally responsive cells

Many cells in the intermediate and deep gray layers of the superior colliculus of the cat respond to both auditory and visual stimuli. These cells have similar receptive fields for both modalities and are directionally selective for both modalities, requiring stimuli moving laterally away from the animal. Perhaps cells that integrate auditory and visual information participate in the control of orienting and following responses to stimuli of both modalities.     

The role of ocular muscle proprioception in visual localization of targets

The role of ocular muscle proprioception in the localization of visual targets has been investigated in normal humans by deviating one eye to create an experimental strabismus. The passively deviated eye was covered and the other eye viewed the target. With a hand-pointing task, targets were systematically mislocalized in the direction of the deviated nonviewing eye. A 4- to 6-degree error resulted when the nonviewing eye was offset 30 degrees from straight ahead. When the eye was deviated, the perceived "straight-ahead" was also displaced, by a similar amount, in the same direction. Since the efferent motor commands to the displaced and to the nondisplaced eyes are presumably identical by the law of equal innervation, the mislocalization of visual objects must be attributed to the change in proprioceptive information issued from the nonviewing, deviated eye. Thus proprioception contributes to the localization of objects in space.     

Paradoxical effects after microinjection of morphine in the periaqueductal gray matter in the rat

Paradoxical, concurrent hyper-and hyporeactivity of a profound nature to specific stimuli occurred when 10 micrograms of morphine was microinjected bilaterally into the periaqueductal gray matter of the rat brain. Both effects at this site were dose-dependent. The hyperreactivity (to previously neutral auditory and visual stimuli) was obtained only with intracerebrally injected morphine and never with intraperitoneally injected morphine or with other opiates administered either way. Rapid tolerance to toxic doses of morphine developed at this site, as well as cross tolerance of the hyporeactivity to painful stimuli between routes (intracerebral to intraperitoneal) of morphine administration. Both the hyper- and hyporeactivity were fully reversible by intracerebral injection of naloxone in the periaqueductal gray. Thus, the periaqueductal gray appears to be a major pathway for morphine action.