Involvement of the Thalamocortical System in Epileptic Loss of Consciousness

  title={Involvement of the Thalamocortical System in Epileptic Loss of Consciousness},
  author={George K. Kostopoulos},
Summary: Experiments on putative neuronal mechanisms underlying absence seizures as well as clinical observations are critically reviewed for their ability to explain apparent “loss of consciousness.” It is argued that the initial defect in absences lies with corticothalamic (CT) neuronal mechanisms responsible for selective attention and/or planning for action, rather than with those establishing either the states or the contents of consciousness. Normally, rich thalamocortical (TC)–CT… 

Cellular and network mechanisms of genetically-determined absence seizures.

Recent findings showing that, in both the thalamus and the neocortex, genetically-determined, absence-related spike-and-wave discharges are the manifestation of hypersynchronized, cellular, rhythmic excitations and inhibitions that result from a combination of complex, intrinsic, synaptic mechanisms are integrated.

Persistence of Cortical Sensory Processing during Absence Seizures in Human and an Animal Model: Evidence from EEG and Intracellular Recordings

Absence seizures are caused by brief periods of abnormal synchronized oscillations in the thalamocortical loops, resulting in widespread spike-and-wave discharges (SWDs) in the electroencephalogram

Dynamics of networks during absence seizure's on- and offset in rodents and man

Improvements in signal analytical techniques, applied to both animal and human fMRI, EEG, MEG, and ECoG data, greatly increased understanding and challenged several, dogmatic concepts of SWD, demonstrating that SWD are not primary generalized, are not sudden and unpredictable events.

Regulation of Thalamic and Cortical Network Synchrony by Scn8a

The Default Mode Network and Altered Consciousness in Epilepsy

It is proposed that the resulting loss of consciousness in all three types of seizures is due to active inhibition of subcortical arousal systems that normally maintain default mode network activity in the awake state, and that these findings support a general “network inhibition hypothesis”, by whichactive inhibition of arousal systems by seizures in certain cortical regions leads to cortical deactivation in other cortical areas.

Why do Seizures Cause Loss of Consciousness?

  • H. BlumenfeldJacob Taylor
  • Psychology, Biology
    The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry
  • 2003
The authors review previous investigations of impaired consciousness in epilepsy and describe new findings that may shed light on both normal and abnormal mechanisms of consciousness.

Firing dynamics of thalamic neurones during genetically determined experimental absence seizures

The firing dynamics of thalamic neurones observed are a crucial step towards understanding TC network activity during AS, and provide a significant insight into the role of the thalamus in alterations of sensation, movement, and consciousness associated with these seizures.

Epilepsy and Consciousness

Impaired consciousness in epilepsy




Some neurophysiologic aspects of consciousness.

  • J. Bogen
  • Psychology
    Seminars in neurology
  • 1997
This combination of anatomic and neurologic evidence is bolstered by a variety of physiologic evidence leading to the conclusion that further investigations of the ILN, and their interaction with lower centers as well as cerebral cortex, are most apt to yield a better understanding of consciousness.

Consciousness as a Neurological Concept in Epileptology: A Critical Review

  • P. Gloor
  • Psychology, Biology
  • 1986
Summary: This essay explores the usefulness of the concept of consciousness in epileptology and concludes that it does not further the understanding of seizure mechanisms and brain function. The

Basic mechanisms of generalized absence seizures

Increasing understanding of the basic mechanisms that underlie generalized absence seizures promises to allow, for the first time, a rational design of drug treatment for a seizure disorder based on the pathogenesis of that disorder.

The neuronal basis for consciousness.

The goal of this paper is to explore the basic assumption that large-scale, temporal coincidence of specific and non-specific thalamic activity generates the functional states that characterize human cognition.

Pathophysiological mechanisms of genetic absence epilepsy in the rat

Demonstration of thalamic activation during typical absence seizures using H2(15)O and PET.

This study provides evidence for the key role of the thalamus in the pathogenesis of absence seizures but was unable to show that it is the site of initiation of the seizures.

Demonstration of thalarnic activation during typical absence seizures using H2 15O and PET

Evidence is provided for the key role of the thalamus in the pathogene-sis of absence seizures but it is unable to show that it is the site of initiation of the seizures.

Neurobiological basis of consciousness.

The brain has the capacity for self-awareness, ie, awareness that one has certain cognitive and mental processes, and traditionally at the "highest level" of cognitive functioning (eg, deductive reasoning), involves the synthesis of the above-listed components.