Photic-induced sensitization: acquisition of an augmenting spike-wave response in the adult rat through repeated strobe exposure.

It is well established that patterns of sensory input can affect neuroplastic changes during early development. The scope and consequences of experience-dependent plasticity in the adult are less well understood. We studied the possibility that repeated exposure to trains of stroboscopic stimuli could induce a sensitized and potentially aberrant response in ordinary individuals. Chronic electrocorticographic recording electrodes enabled measurement of responses in awake, freely moving animals. Normal adult rats, primarily Sprague-Dawley, were exposed to 20-40 strobe trains per day after a strobe-free adaptation period. The common response to strobe trains changed in 34/36 rats with development of a high-amplitude spike-wave response that emerged fully by the third day of photic exposure. Onset of this sensitized response was marked by short-term augmentation of response to successive strobe flashes. The waveform generalized across the brain, reflected characteristics of the visual stimulus, as well as an inherent 6- to 8-Hz pacing, and was suppressed with ethosuximide administration. Spike-wave episodes were self-limiting but could persist beyond the strobe period. Sensitization lasted 2-4 wk after last strobe exposure. The results indicate visual stimulation, by itself, can induce in adult rats an enduring sensitization of visual response with epileptiform characteristics. The results raise the question of the effects of such neuroplastic change on sensation and epileptiform events.

The anticonvulsant and proconvulsant effects of alpha2-adrenoreceptor agonists are mediated by distinct populations of alpha2A-adrenoreceptors.

The alpha2-adrenoreceptor (AR) is the most investigated noradrenergic receptor with regard to modulation of seizure activity. However, because of the complexity of multiple alpha2-AR subtypes and their distribution, the exact role of this receptor in modulating seizure activity is not clear. alpha2A- and alpha2C-ARs function as both autoreceptors (presynaptic) on noradrenergic neurons, where they regulate norepinephrine (NE) release, and as postsynaptic receptors on neurons that receive noradrenergic innervation, where they regulate the release of other neurotransmitters (heteroreceptor). The nonselective alpha2-AR agonist clonidine produced a proconvulsant effect on seizure susceptibility, while the selective alpha2A-AR agonist guanfacine was anticonvulsant. The effects of both alpha2-AR agonists were absent in alpha2a knockout mice, suggesting that the alpha2A-AR mediates the proconvulsant and anticonvulsant effect of alpha2-AR agonists on seizure susceptibility. To determine whether the alpha2-AR agonists were acting on inhibitory presynaptic autoreceptors to decrease NE release or on postsynaptic receptors on NE target neurons, the effects of clonidine and guanfacine were determined in dopamine beta-hydroxylase knockout (Dbh -/-) mice that lack NE. The anticonvulsant effect of guanfacine persisted in Dbh -/- mice, suggesting that guanfacine may act preferentially on alpha2A-postsynaptic receptors that regulate the action of NE on target neurons. In contrast, the proconvulsant effect of clonidine was lost in Dbh -/- mice, suggesting that clonidine may act on presynaptic autoreceptors to decrease NE release. We hypothesize that the alpha2A-presynaptic autoreceptor is responsible for the proconvulsant effect of alpha2-AR agonists, while the alpha2A-postsynaptic receptor is responsible for the anticonvulsant effect of alpha2-AR agonists. These data help to clarify the inconsistent effects of alpha2-AR agonists on seizure activity.

'Top 10' LIS vendors jockey for position.

The laboratory information system market remains volatile despite a "flattening out" in overall sales, says industry consultant and analyst Sheldon I. Dorenfest. Vendors that were giants just a few years ago have been felled by smaller competitors, but no company can afford to rest easy in its current position.

User interfaces: where the rubber meets the road.

Today's users face a dizzying array of interface tools from which to choose. Keyboard, mouse, voice or touchscreen, Windows, pull-down menus, point-and-click--so many choices, but which is best?

Telecommunications may offer poor a 'road' to healthcare.

A report by the Environmental Science and Policy Institute paints a picture of a healthcare telecommunications "super highway" system with on and off ramps leading directly to the most disaffected in our society. It offers an inviting tour into the possibilities of tomorrow, but is it realistic?

Fledgling CPRI (Computer-Based Patient Record Institute) faces difficult challenges as legislative clock ticks.

A diverse group of users, vendors, employers, insurers and government officials met in Washington in July for the Computer-Based Patient Record Institute's First Annual Meeting. Deemed "the focal point" of legislation demanding automated patient records, their task was to overcome a myriad of differences and form a true coalition that can meet an ambitious, and some say unrealistic, deadline.

Executive information systems: winning the numbers game.

Boosting business by putting information to work--that's the premise behind executive information systems. Here's what an EIS can do for organizations, and some systems currently offered.

Healthcare industry to benefit from 'Baby Bell' court ruling.

Courts have cleared the way for regional Bell operating companies to sell electronic information. Although critics are fearful of the Baby Bells' power, others say the decision will open a myriad of possibilities that could have far-reaching effects on the healthcare industry.

Electronic claims are smart way to trim costs, share outcomes.

Health and Human Services wants to trim the administrative fat from the country's $666 billion healthcare bill. The Hartford Foundation is letting bids for a system that allows individual communities to share healthcare data for a variety of purposes. Both efforts draw significantly on electronic media claims.