Beyond one-bun, two-shoe: recent advances in the psychological rehabilitation of memory disorders after acquired brain injury

Memory disorders are one of the most frequent types of cognitive impairment encountered in neurological populations. The more severe degrees of such impairment case major disability and handicap, and have a profound impact on a person's capacity to engage in independent living. To date, commonly used remediation strategies range from drills and practice, including computer-based tasks, to mnemonic techniques and memory notebooks. In general, these therapies have met with varying degrees of success. The last decade has seen exciting developments in remediation techniques for memory disorders, a number of which are based on implicit learning skills, as well as programmes tailored to an individual's unique pattern of deficits. The present paper provides an overview of this literature and discusses issues relating to their application in rehabilitation programmes.     

Cellular depletion of p56lck during thymocyte apoptosis

The src-related protein tyrosine kinase p56lck is thought to be important in regulating maturation and functional responsiveness of T cells and thymocytes. In the present studies we report that expression of p56lck is suppressed during apoptosis. Using primary cultures of rat thymocytes, we found that agents that are effective in inducing apoptosis, including okadaic acid, dexamethasone, and antibodies to the CD3 receptor, also deplete cells of p56lck. This process is rapid, occurring within 24 h, and is not due to cytotoxicity. Inhibition of DNA fragmentation in apoptotic cells with the endonuclease inhibitor ZnCl2 failed to prevent depletion of p56lck, suggesting that it was not a consequence of the DNA degradation process. Using the thymic lymphoma cell line LSTRA, apoptosis was also associated with cellular depletion of p56lck. In contrast to thymocytes, this process required 48-72 h possibly because these cells overexpress p56lck. Although at this time we are uncertain as to the precise role of p56lck in the process of apoptosis, our results indicate that changes in the expression of this protein in thymocytes is an important marker of programmed cell death.     

Targeting acetylcholinesterase molecules to the neuromuscular synapse

The functional integrity of the neuromuscular synapse requires that sufficient numbers of acetylcholinesterase (AChE) molecules be localized on the specialized extracellular matrix between the nerve terminal and the post-synaptic membrane. Multiple interrelated levels of regulation are necessary to accomplish this complex task including the spatial and temporal restriction of AChE mRNA expression within the muscle fiber, local translation and assembly of AChE polypeptides, and focused accumulation of AChE molecules on the extracellular matrix. This is accomplished in part through the organization of other extracellular matrix molecules into a complex which further associates with acetylcholine receptors and their accompanying molecules. Finally, the mature neuromuscular junction contains molecules which can act as receptors for the attachment of AChE which in turn may allow for the turnover of this enzyme at the synapse. This brief review will focus mainly on contributions from our laboratory towards understanding the mechanisms involved in organizing AChE molecules at the neuromuscular synapse.     

Production and perception of final consonant voicing in speech produced by inexperienced signers during simultaneous communication

Simultaneous communications combines both spoken and manual modes to produce each word of an utterance. This study investigated the potential influence of alterations in the temporal structure of speech produced by inexperienced signers during simultaneous communication on the perception of final consonant voicing. Inexperienced signers recorded words that differed only in the voicing characteristic of the final consonant under two conditions: (1) speech alone and (2) simultaneous communication. The words were subsequently digitally edited to remove the final consonant and played to 20 listeners who, in a forced-choice paradigm, circled the word they thought they heard. Results indicated that accurate perception of final consonant voicing was not impaired by changes in the temporal structure of speech that accompanied the inexperienced signers' simultaneous communication.     

Bilateral detection thresholds in dextrals and sinistrals reflect the more sensitive side of the nose, which is not lateralized

Recent studies have shed light on the different relationships between odorant receptor expression and the specification of neural identity in the olfactory systems of vertebrates and invertebrates. In mice, neuronal identity and axon guidance are specified by the single expressed olfactory receptor, whereas in C. elegans, neuronal identity appears to be independent of receptor expression.