共查询到20条相似文献,搜索用时 0 毫秒
1.
Kostandov EA Farber DA Machinskaia RI Cheremushkin EA Ashkinazi ML Petrenko NE 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》2006,56(4):472-480
Changes in the alpha-rhythm synchronization were revealed at different stages of cognitive visual set in 5- to 7-year-old children. We found a clear-cut correlation of these changes with set plasticity. In children with a plastic set, the EEG synchronization between the frontal and other brain regions substantially increased in the period of set-shifting (the actualization stage). At the set extinction stage, after set-shifting has already taken place, the EEG-synchronization becomes minimal. On the contrary, in children who formed a rigid set, EEG coherence considerably increases at the set extinction stage. This finding suggests that the rigid set still affects the cognitive activity even after (judging from oral reports) the set shift has been completed. The age-related differences in cognitive set formation clearly correlate with the time course of the EEG synchronization between the frontal and other brain regions. We think that the ability to form a plastic visual set depends on the frontal cortex maturation, which occurs at the age of 6-7 years, and its age-related effect on the brain cognitive functions. 相似文献
2.
To determine the excitability of the rabbit sensomotor cortex and red nucleus the animal's motor response to electrical stimulation of these structures at threshold strength was investigated. In computerized experiments the excitability of these structures was compared in situations characterized by different degrees of correlation of cortical potentials. An increase in the level of spatial synchronization of cortical potentials was shown to be accompanied by an increase in the excitability of the sensomotor cortex and red nucleus. This increase in excitability is evidently a neurophysiological mechanism of the increase in probability of appearance of an effector response to sensory stimulation when the level of spatial synchronization of cortical potentials is raised.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 9, No. 1, pp. 19–24, January–February, 1977. 相似文献
3.
4.
The tangential neurons in the lobula plate region of the flies are known to respond to visual motion across broad receptive
fields in visual space.When intracellular recordings are made from tangential neurons while the intact animal is stimulated
visually with moving natural imagery,we find that neural response depends upon speed of motion but is nearly invariant with
respect to variations in natural scenery. We refer to this invariance as velocity constancy. It is remarkable because natural scenes, in spite of similarities in spatial structure, vary considerably in contrast, and
contrast dependence is a feature of neurons in the early visual pathway as well as of most models for the elementary operations
of visual motion detection. Thus, we expect that operations must be present in the processing pathway that reduce contrast
dependence in order to approximate velocity constancy.We consider models for such operations, including spatial filtering,
motion adaptation, saturating nonlinearities, and nonlinear spatial integration by the tangential neurons themselves, and
evaluate their effects in simulations of a tangential neuron and precursor processing in response to animated natural imagery.
We conclude that all such features reduce interscene variance in response, but that the model system does not approach velocity
constancy as closely as the biological tangential cell. 相似文献
5.
Jones M. Jr; Sheldon R. E.; Peeters L. L.; Meschia G.; Battaglia F. C.; Makowski E. L. 《Journal of applied physiology》1977,43(6):1080-1084
6.
7.
8.
Parameters of cortical interactions depending on the level of creative achievements were studied in 40 right-handed subjects
(22 men and 18 women). EEG was recorded at rest and during performance of a verbal creativity task (the Cognitive Synthesis
test). The subjects were divided (by the median split) into groups with high and low originality scores (OSs). EEG coherence
was computed within a range of frequencies from 4 to 30 Hz. The total values of coherence were determined separately for intra-
and interhemispheric coherent connections using each of 16 electrode sites. Unlike subjects with a low OS, those with a high
OS values were characterized by a decrease in the interhemispheric coherence of the θ1,2-rhythm bioelectric potentials, which was especially pronounced in frontal cortical regions, and by an increased β1-rhythm interhemispheric coherence in the occipital and temporal-parietal brain regions. The results are discussed in the
context of right- and left-hemisphere contributions into the top-down and bottom-up regulation mechanisms during creative
thinking. 相似文献
9.
L D Luk'ianova V I Bogomolov 《Biulleten' eksperimental'no? biologii i meditsiny》1992,114(12):657-660
A comparative analysis of 339 protein fractions of cerebral cortex of rats both resistant and non-resistant to oxygen deficiency has been fulfilled by means of two-dimensional gel-electrophoresis. A specific group of 9 protein fractions with molecular weights in the range of 32-68 kD was found to be quantitatively changed under hypoxia influence. An activation of labile protein synthesis was a predominant response to acute hypoxia in the resistant rats, while the synthesizing processes in the non-resistant rats were rather weak. An adaptation to hypoxia mostly resulted in the decrease of quantitative representations of labile protein fractions and has been realizing in different ways in resistant and nonresistant rats. The data obtained seem to testify to the changes of protein synthesis under chronic hypoxia conditions in the cerebral cortex chiefly determined by fast adaptation mechanisms. 相似文献
10.
A S Batuev 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1991,41(6):1088-1093
The investigation of neuronal activity of monkey cerebral cortex during delayed spatial choice performance allows to develop a hypothesis about the neuronal networks securing the operative memory. The work of one of them is based on the relay-race and reverberation principles of information transfer. Another neuronal network secures the reliability of the transfer phases of behavioural program. Both of these neuronal networks are represented differently in the prefrontal and parietal associative cortical areas. 相似文献
11.
To form a percept of the multisensory world, the brain needs to integrate signals from common sources weighted by their reliabilities and segregate those from independent sources. Previously, we have shown that anterior parietal cortices combine sensory signals into representations that take into account the signals’ causal structure (i.e., common versus independent sources) and their sensory reliabilities as predicted by Bayesian causal inference. The current study asks to what extent and how attentional mechanisms can actively control how sensory signals are combined for perceptual inference. In a pre- and postcueing paradigm, we presented observers with audiovisual signals at variable spatial disparities. Observers were precued to attend to auditory or visual modalities prior to stimulus presentation and postcued to report their perceived auditory or visual location. Combining psychophysics, functional magnetic resonance imaging (fMRI), and Bayesian modelling, we demonstrate that the brain moulds multisensory inference via two distinct mechanisms. Prestimulus attention to vision enhances the reliability and influence of visual inputs on spatial representations in visual and posterior parietal cortices. Poststimulus report determines how parietal cortices flexibly combine sensory estimates into spatial representations consistent with Bayesian causal inference. Our results show that distinct neural mechanisms control how signals are combined for perceptual inference at different levels of the cortical hierarchy.A combination of psychophysics, computational modelling and fMRI reveals novel insights into how the brain controls the binding of information across the senses, such as the voice and lip movements of a speaker. 相似文献
12.
13.
14.
Sardesai M Figge C Bodner M Crosby M Hansen J Quillfeldt JA Landau S Ostling A Vuong S Shaw GL 《Biological cybernetics》2001,84(3):173-182
It has previously been shown that Hebb learning in a single column in the trion model of cortical organization occurs by
selection. Motivated by von Neumann's solution for obtaining reliability and by models of circulating cortical activity, we
introduce Hebb intercolumnar couplings to achieve dramatic enhancements in reliability in the firing of connected columns.
In order for these enhancements to occur, specific temporal phase differences must exist between the same inherent spatial-temporal
memory patterns in connected columns. We then generalize the criteria of large enhancements in the global firing of the entire
connected columnar network to investigate the case when different inherent memory patterns are in the columns. The spatial
rotations as well as the temporal phases now are crucial. Only certain combinations of inherent memory patterns meet these
criteria with the symmetry properties playing a major role. The columnar order of these memory patterns not in the same symmetry family can be extremely important. This yields the first higher-level architecture of a cortical language and grammar within the
trion model. The implications of this result with regard to an innate human language and grammar are discussed.
Received: 14 June 2000 / Accepted in revised form: 25 July 2000 相似文献
15.
Changes of morphological and neurophysiological characteristics of pyramidal neurons in response to complete ischemia have been studied by means of vital microscopy of cat and rabbit cortex neurons in addition to some other cytological methods. These responses were found to be complex involving phasic changes in the neuron size, membrane potential and redox potential. Neurons of particular types responded to normo- and hypothermic ischemia differently. Pyramidal neurons retained their vital ability for the whole prolonged period of the complete ischemia (up to 40--60 min). 相似文献
16.
We investigated the effects of various phospholipids on the presynaptic levels of newly synthesized [3H]acetylcholine (ACh) in rat cerebral cortical synaptosomes. When administered as small unilamellar vesicles (200–500 Å diameters) dipalmitoylphosphatidylcholine (DPPC) reduced [3H]ACh levels in concentration and time-related manners, while increasing the efflux of labelled choline to a similar extent. The reductions in synaptosomal [3H]-ACh levels induced by DPPC (3 mg/ml) were found in the cytosolic S3 but not microsomal P3 fraction, arguing for a cytoplasmic, nonvesicular site of action. DPPC-induced reductions in [3H]ACh levels were blocked by 100 M eserine, a tertiary amine cholinesterase inhibitor, but not with 100 M neostigmine, a quaternary ammonium inhibitor. Large unilamellar vesicles (2000–5000 Å diameters) consisting of soybean-phosphatidylcholine reduced [3H]ACh levels to the same extent that small vesicles did at the same concentration (3 mg/ml). Taken together, these results suggest that DPPC can fuse with membranes to increase the hydrolysis of cytoplasmic ACh via a small intra-terminal subpopulation of cholinesterases. 相似文献
17.
18.
J Crousillat F Ranieri 《Comptes rendus des séances de la Société de biologie et de ses filiales》1977,171(3):602-607
Using the occlusion method, we have shown splanchno splanchnic interactions on spinal, thalamic and cortical cells in cat. 1. At the first level, splanchno splanchnic interactions concern only the cells located in the Rexed V layer. The splanchnic fibres involved are small sized ones (Agammadelta, B and C types). 2. At the second level, splanchno splanchnic interactions have been observed in the VPL nucleus. The latencies of responses suggest that only large fibres are concerned. 3. At the third level, cortical cells of SI and SII areas have been studied. Splanchno splanchnic interactions have been elicited by different afferent splanchnic fibres (medullated and non medullated ones). 相似文献
19.
E A Kostandov T N Vazhnova O A Genkina N N Zakharova O I Ivashchenko 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1984,34(5):833-840
Adult healthy subjects did not manifest any difference in latency and amplitude of the wave P300 elicited by a positive ("good") and negative ("error") reinforcing stimuli. After the negative reinforcement, the P300 wave amplitude decreases in response to the standard stimulus (light bars) and increases to a lesser degree in response to test stimuli (the same bars but presented with different pauses). In the processes of learning to assess time microintervals in comparison with the standard, the latency of wave P300 to the test stimuli shortens. It is suggested that formation and consolidation of feedback connection elaborated with the participation of a reinforcing verbal stimulus constitute the physiological basis for learning of comparative assessment of time microintervals. 相似文献