Learning is a fundamental process in neural systems. However, microorganisms without a nervous system have been shown to possess learning abilities. Specifically, Paramecium caudatum has been previously reported to be able to form associations between lighting conditions and cathodal shocks in its swimming medium. We have replicated previous reports on this phenomenon and tested the predictions of a molecular pathway hypothesis on paramecium learning. Our results indicated that in contrast to the previous reports, paramecium can only associate higher light intensities with cathodal stimulation and it cannot associate lower light intensities with cathodal stimulation. These results found to be in line with the predictions of the previously proposed model for the molecular mechanisms of learning in paramecium which depends on the effects of cathodal shocks on the interplay between Cyclic adenosine monophosphate concentration and phototactic behavior of paramecium.
Functional significance of the neural oscillations has been debated since long. In particular, oscillations have been suggested to play a major role in formation of communication channels between brain regions. It has been previously suggested that gamma coherence increases during communication between hemispheres when subjects perceive a horizontal motion in Stroboscopic Alternative Motion (SAM) stimulus. In addition, disruption of this coherence may change the horizontal perception of SAM. In this study, we investigated the changes of Cross-Frequency Coupling (CFC) in EEG signals from parietal and occipital cortices during horizontal and vertical perception of SAM. Our results suggested that while the strength of CFC in parietal electrodes showed no significant change, CFC in P3-P4 electrode-pair demonstrated a significant correlation during horizontal perception of SAM. Therefore, the CFC between theta- and gamma-band oscillations seems to be correlated with changes in functional interactions between brain regions. Accordingly, we propose that in addition to gamma coherence, CFC is perhaps another neurophysiological mechanism involved in neural communication.
Bistable perception is a form of visual illusion that is widely used in the context of brain research. The spinning dancer illusion is a form of bistable perception that can be used to study the perception of motion and rotation. However, the underlying mechanism of such bistability is not fully understood. To determine the possible mechanisms involved, psychophysical methods may provide valuable tools. In the present study, we investigated the effects of stimulus position in the visual field on the duration and number of perceptual reversals in the spinning dancer task. The results indicated that the duration of counterclockwise perception was significantly shorter when the stimulus was presented in the left hemifield compared with the right hemifield (p Ͻ .01). Neural adaptation in the right hemisphere might play a role in shortening the duration of counterclockwise perception in left hemifield trials. We suggest that the usual optical flow can explain the basic clockwise tendency of the right hemisphere in rotation perception. Our results are consistent with previous functional MRI studies, supporting the hypothesis that right hemisphere dominance in motion perception causes a bias toward clockwise perception in the spinning dancer task.
Learning is a cornerstone of intelligent behavior in animals. This behavior has been mostly studied in organisms with a fairly complex nervous system. However, recent reports of learning in unicellular organisms suggested the existence of associative learning in unicellular organisms. In particular, the capability to associate different light intensities with cathodal stimulation in paramecium is of special interest. We have investigated the previous reports on this phenomenon and proposed a molecular mechanism for learning behavior in paramecium. Specifically, we have used the existing evolutionary evidence in order to find the possible molecular pathways that may play a role in Paramecium's learning. Moreover, previous studies have been reviewed in order to propose new experiments that can verify the plausibility of the present hypothesis.
Ultra-weak photon emission in biological objects None-Chemical Distant Cellular Interaction, an explanatory gap Along with the discovery of biophoton emissions, several studies suggested the "intercellular communication" as the biological role of the biophoton emission. In fact, Gurwitsch himself was the first one to report that the onion roots can induce mitosis in each other only by emitting biophotons (1). This early discovery was followed by a load of subsequent studies demonstrating the
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