Measures of tactual detection and temporal order resolution in congenitally deaf and normal-hearing adults.

To guide the development of tactile speech aids, tactual detection and temporal order discrimination by congenitally deaf and normal-hearing adults have been examined. Tactual detection thresholds for sinusoidal vibrations between 2 and 300 Hz were measured at the left thumb and index finger using an adaptive paradigm. Temporal onset- and offset-order discrimination were tested using stimuli of 50 Hz at the thumb and 250 Hz at the index finger, delivered asynchronously and varied independently in amplitude and duration.

Analgesia and hyperalgesia from CRF receptor modulation in the central nervous system of Fischer and Lewis rats.

This study examines the contribution of central corticotropin-releasing factor (CRF) to pain behavior. CRF is the principal modulator of the hypothalamo-pituitary-adrenal (HPA) axis, in addition to acting on many other areas of the central nervous system. We compared nociceptive thresholds (heat and mechanical) and pain behavior in response to a sustained stimulus (formalin test) between Fischer and Lewis rats that have different HPA axis activity.

Dopaminergic input to GABAergic neurons in the rostral agranular insular cortex of the rat.

Increasing evidence shows that the rostral agranular insular cortex (RAIC) is important in the modulation of nociception in humans and rats and that dopamine and GABA appear to be key neurotransmitters in the function of this cortical region. Here we use immunocytochemistry and path tracing to examine the relationship between dopamine and GABA related elements in the RAIC of the rat. We found that the RAIC has a high density of dopamine fibers that arise principally from the ipsilateral ventral tegmental area/substantia nigra (VTA/SN) and from a different set of neurons than those that project to the medial prefrontal cortex.

Schwann cells are removed from the spinal cord after effecting recovery from paraplegia.

Remyelination of the CNS is necessary to restore neural function in a number of demyelinating conditions. Schwann cells, the myelinating cells of the periphery, are candidates for this purpose because they have more robust regenerative properties than their central homologs, the oligodendrocytes. Although the ability of Schwann cells to remyelinate the CNS has been demonstrated, their capacity to enter the adult spinal cord in large numbers and effect functional recovery remains uncertain.

Inducible and reversible gene expression with the rtTA system for the study of memory.

To obtain rapidly inducible and reversible expression of transgenes in the forebrain of the mouse, we have combined the reverse tetracycline-controlled transactivator (rtTA) system with the CaMKIIalpha promoter. We show that doxycycline induces maximal gene expression in neurons of the forebrain within 6 days and that this expression can be reversed by removal of doxycycline. Using calcineurin as a test transgene, we show that doxycycline-induced expression impairs both an intermediate form of LTP (I-LTP) in the hippocampus and the storage of spatial memory.