Peer instruction enhanced meaningful learning: ability to solve novel problems

Students must be able to interpret, relate, and incorporate new information with existing knowledge and apply the new information to solve novel problems. Peer instruction is a cooperative learning technique that promotes critical thinking, problem solving, and decision-making skills. Therefore, we tested the hypothesis that peer instruction enhances meaningful learning or transfer, defined as the student's ability to solve novel problems or the ability to extend what has been learned in one context to new contexts. To test this hypothesis, our undergraduate exercise physiology class of 38 students was randomly divided into two groups: group A (n = 19) and group B (n = 19). A randomized crossover design in which students either answered questions individually or during peer instruction was used to control for time and order effects. The first factor that influences meaningful learning is the degree of mastery of the original material. Importantly, peer instruction significantly enhanced mastery of the original material. Furthermore, the student's ability to solve novel problems was significantly enhanced following peer instruction. Thus pausing two to three times during a 50-min class to allow peer instruction enhanced the mastery of the original material and enhanced meaningful learning, i.e., the student's ability to solve novel problems.     

Neurophysiologic analysis of the bilateral organization of the associative parietal regions of the neocortex in the cat

In cats under Nembutal anesthesia, impulses come to the parietal areas of both hemispheres, which, when evoked by unilateral stimulation of fore- and hind-paws, converge at the same cortical points forming early components of associative responses (ECAR). In responses to contralateral paws' stimulation, individual interhemispheric functional asymmetry is shown. The influence of the contralateral parietal area on the ipsilateral one is more strong than the reverse effect. In contrast to ECAR formation on the contralateral side as a result of the arrival of impulses of specific genesis along the "classical" lemniscal tract,--the signals of the same type participating in the initiation of ECAR in the ipsilateral hemisphere, on their way form a relay in the thalamus and the same zone of the opposite side via the interthalamic commissure and callosal body, correspondingly. It is suggested that along with the arrival of impulses through the mentioned crossed tracts, ECAR generation in the ipsilateral parietal cortex involves impulses, coming through the uncrossed channel of the extralemnisc tract.     

The capacity of dogs to solve problems by operating with the empirical dimensions of figures]

An investigation was made into the dogs capacity for operating with empirical dimensions of figures, i.e. the animal's capacity for solving problems based on the fact that out of two figures a volumetric bait can be placed only in a volumetric figure and not in a flat one. In experiments using two methods (single and multiple presentations of figures, each time of a new pair), the dogs were incapable of solving the problems. They were able, however, to elaborate in the course of learning a visual differentiation of a volumetric figure from a flat one, which implies the formation of a generalization of the volume cue as the only invariant in all the pairs of figures. The investigation into operation with empirical dimensions of figures as one of the objective parameters in estimating elementary reasoning activity of animals indicates that by this criterion dogs range in the philogenetic series by far lower than the previously studied marmoset monkeys and dolphins.     

Effect of destruction of Escherichia coli cells on the catalytic ability of catalase

The possibility for investigation of catalase (CAT) activity under the conditions of intact E. coli cells was estimated. This approach is based on the possibility of hydrogen peroxide freely cross biological membranes. CAT activity of native cells had a broad maximum between pH values 4.5 and 7.5. Desintegration of cells by freezing--thawing and ultrasonication indicated that there were two CAT activity peaks at pH values about 3.5 and 7.0. Activity of CAT with acid pH-optimum decreased at cell desintegration, but one with neutral pH-optimum was rather stable under this procedure. The enzyme in native conditions was less sensitive to the inhibition by high concentrations of hydrogen peroxide than its counterpart from destroyed cells. Activity of CAT in native and desintegrated cell preparations had different sensitivity to heating and inhibition by reduced glutathione, but it was inhibited by azide similarly. Difference in the CAT properties of native and desintegrated bacteria preparations may be explained by different possibility to penetrate cell membrane by reagents and/or by possible modification of the enzyme properties at destruction of native microenvironment.     

Mechanisms of interaction between the parietal association and projection areas of the cat neocortex

Changes in evoked potentials in the first visual (VI), first somatic (SI), and parietal areas of the cortex during local cooling of each area were investigated under pentobarbital anesthesia. Two types of interaction were distinguished. Type I interaction was found in all areas in the early stages of local cooling and was reflected in a similar decrease in amplitude of evoked potentials in intact parts of the cortex. In the thalamic association nuclei — the pulvinar and posterolateral nucleus — somatic evoked potentials were unchanged but visual were transformed differently from those in the cortex. Type IIinteraction was found in the later stages of cooling and only between the association area and each of the projection areas. It was reflected in a greater change in amplitude of the evoked potentials and also in their configuration. In response to somatic stimulation in the early stage of type II interaction transformation of evoked potentials in the cortex took place sooner than in the nuclei; in the later stage it took place immediately after transformation of the "subcortical" evoked potentials. In response to photic stimulation transformations of cortical evoked potentials were always preceded by the corresponding transformations in the nuclei. It is suggested that type I interaction is formed by intercortical connections and type II by direct and subcortical relay connections. Differences in the role of the association area in interaction of types I and II when activated by stimuli of different modalities are discussed.Brain Institute, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 10, No. 6, pp. 573–581, November–December, 1978.     

Conscious awareness of flicker in humans involves frontal and parietal cortex

Even when confined to the same spatial location, flickering and steady light evoke very different conscious experiences because of their distinct temporal patterns. The neural basis of such differences in subjective experience remains uncertain . Here, we used functional MRI in humans to examine the neural structures involved in awareness of flicker. Participants viewed a single point source of light that flickered at the critical flicker fusion (CFF) threshold, where the same stimulus is sometimes perceived as flickering and sometimes as steady (fused) . We were thus able to compare brain activity for conscious percepts that differed qualitatively (flickering or fused) but were evoked by identical physical stimuli. Greater brain activation was observed on flicker (versus fused) trials in regions of frontal and parietal cortex previously associated with visual awareness in tasks that did not require detection of temporal patterns . In contrast, greater activation was observed on fused (versus flicker) trials in occipital extrastriate cortex. Our findings indicate that activity of higher-level cortical areas is important for awareness of temporally distinct visual events in the context of a nonspatial task, and they thus suggest that frontal and parietal regions may play a general role in visual awareness.     

Post-translational modifications of proteins: some problems left to solve

Three major questions regarding the post-translational modification of amino acid side chains in proteins are briefly considered: (1) What are the biological functions of the reactions, (2) what is the specificity of the processing reactions in selecting only a few or sometimes even only one residue for modification, and (3) how do we solve the uniqueness of the processing steps in the production of recombinant proteins? The answers to these questions are not obvious at this time.     

Correlation of neuronal reactions of different regions of the neocortex of the rabbit to conditioned positive and inhibitory stimuli

The activity of neurones of the visual and sensorimotor areas of the neocortex was simultaneously recorded in rabbits under the action of conditioned, inhibitory stimuli (CS, IS) and at simultaneous presentation of CS and the unconditioned stimulus (US) after trans-switching of the positive and inhibitory conditioned reflexes. Mean time of conjugated reactions of simultaneously recorded pairs of neurons is similar under the action of CS, combined action of CS and US and under IS. During the IS action as compared with CS, the phasic activity of some neurones in different areas increased, and due to this the similarity of reactions also increased; in other pairs of neurones the reactions weakened and the responses similarity decreased. The frequency of the appearance of intervals of the conjugated excitation after CS corresponds to 4.3 Hz; under combined action of CS and US it increases up to 5.9 Hz, and after IS--it decreases to 3.6 Hz. The order of coming into conjugated action of different pairs of neurones changes depending on the signal significance of the stimuli.     

How the carotid body works: different strategies and preparations to solve different problems

This is a review of the different experimental approaches developed to solve the problems in our progress towards a comprehensive understanding of how arterial chemoreceptors operate. An analysis is performed oi the bases, advantages and limits of the following preparations: studies of ventilatory reflexes originated from carotid bodies (CBs) in the entire animal; recordings of CB chemosensory discharges in situ; CB preparations perfused in situ; CB explants in oculo; CB explants in ovo; CB preparations incubated in vitro; CB preparations superfused in vitro; CB preparations perfused and superfused in vitro: CB tissue slices in vitro; cells acutely dissociated from CBs; CB cells in tissue culture; petrosal ganglia superfused in vitro; petrosal ganglion cells in tissue culture; and co-cultures of CB and sensory ganglion cells. A brief historical account is given of the passage from one preparation to the next one. Emphasis is placed on personal experience with the different preparations whenever possible. Examples are given of the importance of selecting the appropriate experimental preparation for solving each particular theoretical problem. In fact, brilliant ideas on how the CB works have been unproductive until finding the adequate experimental approach to explore the validity of such ideas.     

Unit responses of the medial group of thalamic nuclei to stimulation of the frontobasal regions of the neocortex

In acute experiments on cats anesthetized with pentobarbital and chloralose, single-unit and focal responses of the medial group of thalamic nuclei (mediodorsal, central lateral, paracentral, central medianum, parafascicular) were studied to stimulation of the frontobasal regions of the cortex (proreal, posterior orbital, basal temporal regions). Depending on the number of neurons responding to cortical stimulation and on the length of the latent period of the responses three functionally heterogeneous subdividions of the medial nuclei were distinguished; the parvocellular and magnocellular portions of the mediodorsal nucleus and the intralaminar nuclei with the parafascicular complex. On the basis of responses of neurons activated antidromically by stimulation of the same cortical region and synaptically by stimulation of another region, the concept of the integrative function of nuclei of the medial group, integrating the frontobasal zones of the neocortex with the aid of neuron circuits in which the medial nuclei are included, is argued.M. Gor'kii Donetsk Medical Institute. Translated from Neirofiziologiya, Vol. 9, No. 1, pp. 11–18, January–February, 1977.