Mechanism of Thalamocortical Augmentation and Repetition

Morison, Robert S.; Dempsey, Edward W.

doi:10.1152/ajplegacy.1943.138.2.297

Cited by 203 publications

(59 citation statements)

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“…Rhythmic (around 10 Hz) stimulation of dorsal thalamic nuclei elicits responses in related neocortical areas that grow in size during the first stimuli (Morison and Dempsey, 1943). The augmenting (or incremental) responses have also been obtained by stimulating the white matter Ferster and Lindström, 1985) or callosal pathways (Nuñez et al, 1993;Steriade et al, 1993b) in thalamic-lesioned animals.…”

Section: Abstract: Augmenting; Plasticity; Thalamus; Intracellular; mentioning

confidence: 99%

Short-Term Plasticity during Intrathalamic Augmenting Responses in Decorticated Cats

Steriade

Timofeev

1997

J. Neurosci.

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The intrathalamic mechanisms of frequency-dependent augmenting responses were investigated in decorticated cats by means of intracellular recordings from thalamocortical ( TC) neurons in ventrolateral (VL) nucleus, including simultaneous impalements from two TC neurons. Pulse trains (10 Hz) applied to VL nucleus elicited two types of augmenting responses: (1) in 68% of cells, the incremental responses occurred on a progressive depolarization associated with the decrease in IPSPs produced by preceding stimuli in the train; (2) in the remaining cells, progressively growing low-threshold (LT ) responses resulted from the enhancement of Cl Ϫ -dependent IPSPs, giving rise to postinhibitory rebound bursts, followed by a selfsustained sequence of spindle waves. Although in some TC cells the augmenting responses developed from LT responses once the latter reached a given level of depolarization, other neurons displayed augmenting responses immediately after the early antidromic spike that depolarized the neuron to the required level, without an intermediate step of LT rebound. Repeated pulse trains led to a progressive and persistent increase in slow depolarizing responses of TC cells, as well as to a persistent and prolonged decrease in the amplitudes of the IPSPs. On the basis of parallel experiments, we propose that the two types of augmentation in TC cells are a result of contrasting responses of thalamic reticular neurons evoked by repetitive thalamic stimuli: decremental responses, which may account for disinhibition leading to depolarizing responses in TC cells, and incremental responses, explaining the progressive hyperpolarization of TC cells. These data demonstrate that frequency-dependent changes in neuronal excitability are present in the thalamus of a decorticated hemisphere and suggest that short-term plasticity processes in the gateway to the cerebral cortex may decisively influence cortical excitability during repetitive responses.

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Section: Abstract: Augmenting; Plasticity; Thalamus; Intracellular; mentioning

confidence: 99%

Short-Term Plasticity during Intrathalamic Augmenting Responses in Decorticated Cats

Steriade

Timofeev

1997

J. Neurosci.

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“…The progressive build-up in response to successive flashes early in the strobe train resembles the thalamocortical augmenting response, a rapidly growing enhancement in cortical evoked responses to repetitive electrical stimulation of the thalamus first described by Dempsey and Morison (1943); also see Bazhenov et al 1998a,b;CastroAlamancos and Connors 1996a,b,c;Morison and Dempsey 1943;Steriade and Timofeev 1997). The augmenting response is proposed to be involved in the generation of sleep spindles and pathological thalamocortical oscillations.…”

Section: Sensitization Reflects Long-and Short-term Changementioning

confidence: 86%

“…In addition, trains of electrical shocks to the thalamus or cortex produce a form of short-term neuroplasticity, the thalamocortical augmenting response (Bazhenov et al 1998a,b;CastroAlamancos and Connors 1996a-c;Dempsey and Morison 1943;Steriade and Timofeev 1997), which in some cases can lead to self-sustaining paroxysmal activity (Steriade et al 1993). Thus we theorized that trains of intense photic stimulation might be efficacious in inducing neuroplastic change leading to photoparoxysmal activity.…”

Section: Introductionmentioning

confidence: 99%

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

Uhlrich¹,

Manning²,

O'Laughlin³

et al. 2005

Journal of Neurophysiology

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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.

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“…The propagation was a different type from that in the AMG kindling. It has been reported that repetitive low-frequency stimulation of the thalamus elicits cortical field potentials with progressively growing amplitudes, termed augmenting responses (25).…”

Section: Discussionmentioning

confidence: 99%

Effects of Antiepileptics on Lateral Geniculate Nucleus–Kindled Seizures in Rats

et al. 2009

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Abstract. The present study was undertaken to clarify the characteristics of lateral geniculate nucleus (LGN) kindling in rats, especially the efficacies of antiepileptics, in comparison with those of amygdala (AMG) kindling. Daily electrical stimulation of the LGN led to the development of a generalized convulsion (kangaroo posture and falling back) in all subjects, similar to AMG kindling. The kindling response of the LGN differed from that of the AMG in a number of respects, that is, a high after-discharge (AD) threshold, a large number of stimulations for completion of kindling, and a different pattern of electroencephalogram (EEG) development. On the other hand, the oral administration of sodium valproate, carbamazepine, clobazam, or zonisamide caused dose-dependent inhibitions of both seizure stage and AD duration of LGN-kindled seizures, whereas ethosuximide had no significant effects. In addition, seizure stage was more potently inhibited than AD duration by these antiepileptics, particularly with clobazam. In conclusion, LGN kindling possesses characteristics that are different from AMG kindling. In addition, it was demonstrated that LGN kindling is a useful model, similar to other types of limbic system kindling, for the evaluation of antiepileptics.

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Mechanism of Thalamocortical Augmentation and Repetition

Cited by 203 publications

References 0 publications

Short-Term Plasticity during Intrathalamic Augmenting Responses in Decorticated Cats

Short-Term Plasticity during Intrathalamic Augmenting Responses in Decorticated Cats

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

Effects of Antiepileptics on Lateral Geniculate Nucleus–Kindled Seizures in Rats

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