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PubMed1982

[Recognition of chemical stimuli by guppy, Poecilia reticulata Peters].

An alimentary conditioned reflex to beta-phenylethanol and a subsequent differentiation of cumarine were elaborated in conditions of simultaneous paired choice in guppies. It was shown that beta-phenylethanol in a concentration not over 7 X 10(-6) M is perceived through olfaction. The conditioned reflex persists for a long time: twenty five to fifty days after section of the olfactory nerves (the conditioned reflex is restored after their regeneration) and at least seventy days in intact fishes.

Animals↗
PubMed1983

The physiological basis of mental images.

An important hypothesis in neurophysiology supposes that sensory information is encoded in spatial patterns of neural activity. A test of this hypothesis in rabbits reveals that the spatial pattern of encephalographic (EEG) activity of the olfactory bulb depends less on odor than on expectation of odor. Analysis of the structure and nonlinear dynamics of the olfactory system suggests that the EEG manifests a neural activity pattern that is an active filter corresponding to what ethologists call a "chemical search image." This first glimpse at the physical aspect of what may be a primitive form of mental image allows us to infer some of its properties. It is self-organized; input destabilizes the bulb, and the event runs a course that is shaped by the initial conditions, the sensory input, the chemical state of the bulb from centrifugal input, and the record of past input embedded in synaptic connections. The event is analog, but not an analog of input. Its intensity pattern exists in two dimensions but it is not a picture. Its bases in feedback and resonance make it connotative and ascriptive, not denotative or descriptive. The neural-mental image is an operator, not an operand. It gathers neurons by the millions into coherent activity and creates information, which it transmits to the next stage in the brain, thereby helping to shape behavior. It cannot be understood without reference to both what the subject does and what is done to it. Its function in the bulb is to regulate olfactory input with minimal and nonspecific centrifugal control.

Animals↗
PubMed1978

Sex-related differences in response to practice on a visual-spatial test and generalization to a related test.

93 first graders (mean age 6.5 years) were given a pretest and posttest on half of the items from the Children's Embedded Figures Test. Half of the children were randomly assigned to a training condition and received a brief training procedure on visual-spatial disembedding prior to the administration of the posttest. Children in the control condition received no training. The performance of girls improved significantly more from pretest to posttest than the performance of boys. Boys and girls showed similar beneficial effects of training in addition to the benefit of direct practice. The tendency that was observed for boys to perform higher than girls on the pretest, p less than .10, was not evident on the posttest. Scores on the pretest predicted scores on a different measure of visual-spatial ability only for children in the control group. The results are interpreted in terms of current theories of sex differences in visual-spatial perception.

Child↗
PubMedDate not supplied

[Mechanisms of visual generalization].

The phenomenon of differentiations transfer from grids of different frequency and orientation to bars of different width and orientation was examined by the method of alimentary motor conditioned reflexes elaborated in free behaving dogs. After formation of differentiations of rectangular high-contrast grids by spatial frequency or orientation, transfer to single lines with the width equal to the width of bars forming the grids, leads to a broadening of the range of frequencies and orientations eliciting a positive response. Due to this fact, differentiations disappear or considerably worsen. The obtained results do not agree with the detector hypothesis according to which a part of receptive fields of the visual cortex are detectors of borders or bars of different width and orientation. But the results are predicted quantitatively by the hypothesis of description of images by receptive fields of the visual cortex as by two-dimensional filtres tuned to different spatial frequencies and orientations.

Animals↗
PubMed1983

Far generalization of visual analogies strategies by impulsive and reflective EMR students.

Cognitive style and its interaction with training effects in promoting the acquisition and far generalization of a visual analogies strategy by 22 male and 17 female EMR pupils was evaluated. Training was effective in producing acquisition and far generalization; cognitive style was not. We suggested that the lack of interaction between cognitive style and training was due to the fact that the training program modified the subjects' cognitive style, i.e., impulsives tended to perform more like reflectives.

Adolescent↗
PubMed1983

Pure tone habituation gradients based on responsiveness to electrical stimuli.

Previous study demonstrated that responsiveness to electrical stimulation of subcortical areas of cats was enhanced if preceded by a tone pip. Habituation occurred when the tone was repeatedly presented. In this study, the capacity for generalization of a habituated tone was measured by occasionally interpolating a tone of different frequency or intensity among a group of monotonously presented standard tones, measuring responsiveness in each case. The responses were: (1) the visual cortical evoked potential, (2) evoked EMG activity, and (3) evoked head movement. Frequency shifts and intensity increases produced recovery of responsiveness at latencies as short as 90 msec, while decreases had no effect on recovery. Responsiveness increased with degree of frequency shift up to 576 Hz, but showed no further increase for greater shifts up to 2304 Hz. A shift of 16 Hz was effective, comparable to behavioral thresholds for frequency discrimination. Thus, these gradients agreed with the form predicted on the basis of central fatigue models of habituation and the bandwidth of the eighth nerve fibers.

Animals↗
PubMedDate not supplied

[Conditioned reflex analysis of functional connections between the hippocampus and limbic system structures].

Instrumental defensive conditioned reflex elaborated in dogs to stimulation of the dorsal and ventral hippocampus, also appeared, due to generalization, in response to stimulation of a number of limbic structures. Two types of changes in the generalization effects (estimated by parameters of motor conditioned reaction) were observed in the course of conditioned reflex stabilization: enhancement (in response to stimulation of the lateral hypothalamus, lateral nucleus of septum, limbic cortex) and weakening toward complete disappearance (in response to stimulation of the medial nucleus of amygdala and medial hypothalamus). Manifestation of the generalization phenomenon from the brain structures, which are not involved initially into conditioned activity, suggests the existence of close functional connections between these structures and the hippocampus.

Amygdala↗
PubMedDate not supplied

[Role of the frontal cortex--caudate nucleus system in implementing the function of generalization].

A comparative analysis of functional contribution of the caudate nucleus and frontal cortex to the cats behaviour was carried out by means of their neurosurgical elimination. It was shown on the model of alternative choice that the morpho-functional caudate frontal link is critically necessary for the mechanisms of comparison, singling out and generalization of essential characteristics in the integrative brain activity based on the euristic principle of empiric regularity search. The caudate nucleus ensures the formation of the simpliest analogues of pre-verbal notions, while the frontal cortex is responsible for the machanisms of elementary abstractions, necessary for objects classification processes.

Animals↗