Photic-Induced Sensitization: Acquisition of an Augmenting Spike-Wave Response in the Adult Rat Through Repeated Strobe Exposure

Abstract

J Neurophysiol 94: 3925-3937, 2005; doi:10.1152/jn.00724.2005. 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.

A new description of epileptic seizures based on dynamic analysis of a thalamocortical model

“…Epileptic seizure in photosensitive epilepsy patients is most frequently induced by 15 Hz flicker stimulus when the eyes are open 80 and 10 Hz stimulus when the eyes are closed 81 , which can confirm the resonance nature of epileptic seizures. Based on this hypothesis, one can also expect to induce seizure in animal models more effectively by choosing the stimulation frequency close to the resonance frequency of their brains 82 , 83 . In addition, factors and conditions that change the brain state to a relatively lower frequency and higher amplitude oscillations (e.g.…”

Visual Experience Induces Long-Term Potentiation in the Primary Visual Cortex

“…Our results here demonstrate that dLGN TBS-induced LTP can dramatically enhance both visual acuity and contrast sensitivity, at least at the level of the VEP, across a wide range of stimulus orientations. Recent work has suggested that it is possible to non-invasively induce LTP in primary sensory cortices of rats (Manning et al, 2007; Uhlrich et al, 2005) and humans (Clapp et al, 2005a; Clapp et al, 2005b) using photic or auditory tetani. Another alternative may be the use of transcranial magnetic stimulation (TMS), either on its own or in conjunction with visual stimulation, to non-invasively deliver a potentiating tetanus (see (Cooke and Bliss, 2006) for review).…”

Synaptic information transfer in computer models of neocortical columns

“…We expect that the gradual reduction in information flow-through with increased internal weight strength will be asymptotic: at the most extreme, the highly interconnected network will be epileptic and any input will ignite a seizure that is unrelated to the input (Uhlrich et al 2005). At a lower level of dynamic pathology, abnormalities in power and coordination in gamma bands might be seen, as has been noted in schizophrenia (Uhlhaas et al 2006; Spencer et al 2004, 2003; Uhlhaas and Singer 2006).…”