Drugs affecting RNA and learning

The molecular memory code and synaptic plasticity: A synthesis

The most widely accepted view of memory in the brain holds that synapses are the storage sites of memory, and that memories are formed through associative modification of synapses. This view has been challenged on conceptual and empirical grounds. As an alternative, it has been proposed that molecules within the cell body are the storage sites of memory, and that memories are formed through biochemical operations on these molecules. This paper proposes a synthesis of these two views, grounded in a computational model of memory. Synapses are conceived as storage sites for the parameters of an approximate posterior probability distribution over latent causes. Intracellular molecules are conceived as storage sites for the parameters of a generative model. The model stipulates how these two components work together as part of an integrated algorithm for learning and inference.

Can memory exist outside of brain and be transferred? Historical review, issues & ways forward

Learning and memory are among the executive functions attributed to intelligent forms of life. Unfortunately, there is a lack of clear understanding regarding the underlying mechanisms governing these functions. Most of the modern day scientists attribute these functions solely to brain. However, in the latter half of last century, a number of reports suggested existence of extra-cranial memory and potential of its transfer between animals. Some have linked this phenomenon to RNA while others believed that peptides were responsible. The terms like "educated RNA" and "scotophobin" were coined. This atypical work involving flatworms, yeast RNA and scotophobin was received with deep skepticism and ultimately disregarded. However, the recent reproduction of some of this earlier work by scientists at Tufts University has reignited the debate on the mechanisms of learning and memory. Keeping this in view, we believe it is high time to summarize this historical work and discuss the possibilities to delineate these atypical claims. The objective is to incite the present day researchers to explore this opportunity under the perspective of newer advancements in science.

The inverse relationship between nonverbal intelligence and the latency of the Hoffmann reflex from the right and left thenar muscles in right- and left-handed subjects

The relationship between nonverbal reasoning ability and the latency of the Hoffmann (H) reflex was studied in right- and left-handed subjects. The nonverbal reasoning ability was assessed by the Cattell's Culture Fair Intelligence test. Hand preference was assessed by the Edinburgh Handedness Inventory. Hoffmann reflex was recorded from thenar muscles of the right and left thumbs. In left-handers (total sample), IQ was found to be significantly and negatively linearly related to the H-reflex latency from the left side. In strong left-handers, there was a significant negative linear relationship between IQ and the H-reflex latency from right and left sides, but with a higher correlation for the left side. In weak left-handers, IQ did not show any significant relation to the H-reflex latencies from the right and left sides. In right-handers (total sample), there was a significant negative linear correlation between IQ and the H-reflex latency from the right side. In right-handed women without familial sinistrality (FS-), IQ was found to be inversely related to the H-reflex latency from the right and left side, but with a higher correlation for the right side. In right-handed women with FS, IQ did not show any significant relation to the H-reflex latency from the right and left sides. In right-handed men with right eye preference and FS-, IQ was found to be negatively linearly related to the H-reflex latency from the right and left sides equally. In right-handed men with right eye FS+, mixed eye FS-, +, mixed eye-right foot (FS-), mixed eye-mixed foot, and left eye preference there was no significant relationship between IQ and the H-reflex latency from the right and left sides. Only in strong left-handers there was a significant, positive linear correlation between IQ and the right minus left (R-L) difference of latencies. The H-reflex latency from the right and left sides was not significantly correlated with the R-L difference of latencies in left-handers. In right-handed women with right eye preference FS-, and in right-handed men with right eye preferences FS-, The H-reflex latency from the right side was found to be positively linearly correlated with the R-L difference of latencies. In right-handed women FS+, and in right-handed men FS+, and mixed or left eye preference, the H-reflex latency from the left side was found to be negatively linearly related to the R-L difference of latencies.(ABSTRACT TRUNCATED AT 400 WORDS)

Neuropeptides induce directional asymmetry in brain and spinal cord: facts and hypotheses

Directional behavioral and functional asymmetries (i.e., left-biased or right-biased in all or most animals of the population) induced by certain chemical substances are new types of brain and spinal cord asymmetry. The revealed asymmetry comprises: (1) left- or right-biased circle rotation in rat, (2) hind limb postural asymmetry resulting from alteration of the left or right flexion reflex in rat and cat, and (3) asymmetric alterations of the evoked potentials (EP) in the turtle visual cortex. Circle rotation of animals is induced by hypothalamic neurohormones (somatostatin, LH-RH, substance P, and TRH). Postural asymmetry develops under the effect produced by enkephalins and opioid kappa- and delta-agonists, sigma-agonist SKF 10.047, Arg-vasopressin. Endogenous peptide factors, the activity (or content) of which increased under brain and spinal cord unilateral injury, as well as the ones localized in the left or right hemisphere, also induced postural asymmetry. EP of the left and right turtle visual cortex were inhibited by enkephalins and opioid kappa-, and delta- and mu-agonists, and factors predominantly localized in the left or right turtle visual cortex in a different manner. The data reported here suggest the existence of a side-specific mechanism for a selective neurohormonal regulation of the neuronal activity and other processes in the left and right halves of brain and spinal cord which involves lateralized neuropeptides and their receptors. This mechanism might serve to maintain a certain balance between the activity of the left and right-side neurons, and other contralateral processes in the paired and bilateral structures in brain and spinal cord. Significant deviations from the balance occur most likely due to powerful unilateral stimuli, e.g., unilateral trauma. Many neuropeptides (opioid ones, somatostatin, MSH, ACTH) are, presumably, involved in the regeneration processes in the central and peripheral nervous system. In the case of brain lesions, some lateralized endogenous peptides may participate in the regulation of regeneration process on the left, whereas the other ones, on the right side of the midline, which depends on the side of the lesion. Some lateralized receptors and ligands may serve as positional markers of the left, whereas the other ones may serve as those of the right brain hemisphere. In ontogenesis, these markers are probably necessary to perform the function of the mechanism responsible for symmetrical brain formation.

Cretinism in rats: enduring behavioral deficit induced by tricyanoaminopropene

Rats reared on diets containing tricyanoaminopropene, the antithyroid compound that stimulates RNA synthesis, showed a deficit in performance on automated closed-field maze tests many weeks after discontinuation of the drug. The rats were also tested while still receiving the drug, and performance deficits were indicated in tests of Y-maze reversal and manual closed-field maze performance; rats treated with the drug and with thiouracil behaved in a highly similar fashion on several tasks. No evidence of facilitation by tricyanoaminopropene appeared in any of the eight learning situations used. Exposure to tricyanoaminopropene before and after birth, at doses sufficient to produce anatomical cretinism, apparently induces an enduring behavioral deficit which is similar to that of neonatal thyroidectomy-induced cretinism in rats and which parallels the mental retardation associated with human cretinism.

The biochemical basis of long-term memory

Learning and memory are important elements of our daily lives, familiar to all through introspection. Yet the mechanisms underlying these processes are still for the most part unknown. Here are problems which combine a maximum of intrinsic and practical interest with a minimum of actual knowledge and understanding. Years of our lives are dedicated to the formation of certain long-term memories and behaviour patterns, yet we have only rudimentary notions of how such ‘schooling’ is best accomplished. There is no certainty in any aspect of the process. We are not sure whether relatively few cells or millions participate in a memory trace; whether these cells change as a whole, or whether the changes are limited to synaptic regions. In fact, we cannot be certain whether the changes are confined to the neurones or whether the glia also participate.

Magnesium pemoline: enhancement of brain RNA polymerases

The stimulation by magnesium pemoline of systems that synthesize brain nucleic acid was studied in vivo and in vitro. There are differential effects between true RNA polymerase and pseudo-RNA polymerase. The selective stimulation of true RNA polymerase by magnesium pemoline was not observed with stimulants of the central nervous system and psychotropic agents.

Magnesium pemoline: enhancement of learning and memory of a conditioned avoidance response

Magnesium pemoline, a mild stimulant of the central nervous system, enhances the acquisition and retention of a conditioned avoidance response in rats. Methamphetamine and methylphenidate do not have this effect.

Puromycin Effect on Memory Fixation in the Goldfish

Puromycin injected intracranially into the goldfish produces impairment of memory for a shock-avoidance response. Intracranial injection of puromycin aminonucleoside, or of saline has no effect. Puromycin does not afject performance in naive or overtrained goldfish.