Incubation effects in behavior induction in rats

piRNAs and endo-siRNAs: Small molecules with large roles in the nervous system

Since their discovery, small non-coding RNAs have emerged as powerhouses in the regulation of numerous cellular processes. In addition to guarding the integrity of the reproductive system, small non-coding RNAs play critical roles in the maintenance of the soma. Accumulating evidence indicates that small non-coding RNAs perform vital functions in the animal nervous system such as restricting the activity of deleterious transposable elements, regulating nerve regeneration, and mediating learning and memory. In this review, we provide an overview of the current understanding of the contribution of two major classes of small non-coding RNAs, piRNAs and endo-siRNAs, to the nervous system development and function, and present highlights on how the dysregulation of small non-coding RNA pathways can assist in understanding the neuropathology of human neurological disorders.

The First Annual Meeting of the Society for Neuroscience, 1971: Reflections Approaching the 50th Anniversary of the Society's Formation

The formation of the Society for Neuroscience in 1969 was a scientific landmark, remarkable for the conceptual transformation it represented by uniting all fields touching on the nervous system. The scientific program of the first annual meeting of the Society for Neuroscience, held in Washington, DC in 1971, is summarized here. By reviewing the scientific program from the vantage point of the 50th anniversary of the Society for Neuroscience, the trajectory of research now and into the future can be tracked to its origins, and the impact that the founding of the Society has had on basic and biomedical science is evident. The broad foundation of the Society was firmly cast at this first meeting, which embraced the full spectrum of science related to the nervous system, emphasized the importance of public education, and attracted the most renowned scientists of the day who were drawn together by a common purpose and eagerness to share research and ideas. Some intriguing areas of investigation discussed at this first meeting blossomed into new branches of research that flourish today, but others dwindled and have been largely forgotten. Technological developments and advances in understanding of brain function have been profound since 1971, but the success of the first meeting demonstrates how uniting scientists across diversity fueled prosperity of the Society and propelled the vigorous advancement of science.

Imaging learning: the search for a memory trace

Learning is associated with structural changes in the human brain that can be seen and studied by MRI. These changes are observed in gray matter and surprisingly also in white matter tissue. Learning a wide range of skills, from sports, computer games, music, and reading, to abstract intellectual learning, including classroom study, is associated with structural changes in appropriate cortical regions or fiber tracts. The cellular changes underlying modifications of brain tissue during learning include changes in neuronal and glial morphology as well as vascular changes. Both alterations in axon morphology and myelination are thought to contribute to white matter plasticity during learning but to varying degrees depending on age. Structural changes in white matter could promote learning by improving the speed or synchrony of impulse transmission between cortical regions mediating the behavior. Action potentials can stimulate oligodendrocyte development and myelination by at least three known mechanisms that involve signaling molecules between axons and oligodendrocytes, which do not require neurotransmitter release from synapses. Integrating information from cellular/molecular and systems-level research on normal cognitive function, development, and learning is providing new insights into the biological mechanisms of learning and the structural changes produced in the brain.

Non-cell autonomous RNA silencing

In plants and in some animals, the effects of post-transcriptional RNA silencing can extend beyond its sites of initiation, owing to the movement of signal molecules. Although the mechanisms and channels involved are different, plant and animal silencing signals must have RNA components that account for the nucleotide sequence-specificity of their effects. Studies carried out in plants and Caenorhabditis elegans have revealed that non-cell autonomous silencing is operated through specialized, remarkably sophisticated pathways and serves important biological functions, including antiviral immunity and, perhaps, developmental patterning. Recent intriguing observations suggest that systemic RNA silencing pathways may also exist in higher vertebrates.

Positive interanimal transfer with a control for arousal

Three experiments used rats and a non-shock passive avoidance task to differentiate between learning and non-specific arousal hypotheses of the interanimal transfer phenomenon. In the first experiment with 57 rats, a multi-trial training procedure was used and positive transfer was obtained from rats receiving “trained-brain” extract injections but not from rats receiving injections of extracts from aroused controls. The second experiment used a one-trial training procedure with 49 rats and reproduced the results of Exp. 1. The third experiment with 56 rats showed some evidence of extinction and spontaneous recovery while this was not found with rats receiving injections from aroused controls. A fourth experiment indicated that the brain-extract solutions of Exps. 1 to 3 contained relatively high concentrations of protein. No detectable concentrations of RNA were discerned. The behavioral results were consistent with the notion that the interanimal transfer resulted from a learning transfer rather than a nonspecific arousal transfer.