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Abstract

Absence epilepsy (AE) and nocturnal frontal lobe epilepsy (NFLE) are system epilepsies of the sleep–wake system.1. Absence epilepsy is a well-known idiopathic childhood epilepsy. The spike–wake pattern of absence epilepsy and the non–rapid eye movement (NREM) sleep-related burst-firing mode of the corticothalamic system share the same functional structures in the brain. Absences occur when vigilance decreases, during the transition from waking to NREM sleep, whereas they are inhibited by wakefulness and rapid eye movement sleep. The sensory stimuli reaching the brain during the transition state [cyclic alternating pattern (CAP) A1 phase] elicit “reactive” slow-wave responses and may activate spike–wave responses, whereas those arriving in other states (CAP 2 or 3 NREM sleep) evoke “regular” desynchronization–arousal responses and do not trigger spike–waves.In other words, in terms of states and functions, absence epilepsy seems to be linked to the periods of initiation and shifts toward NREM sleep.2. Autosomal dominant nocturnal frontal lobe epilepsy, the genetic variation of NFLE, is underlain by mutations of the nicotinic acetylcholine receptor system.The acetylcholine receptor (AChE) gene mutations render the cholinergic ascending arousal system oversensitive to arousals during NREM sleep, resulting in arousal-linked seizure fragments and full-blown seizures with different degrees of behavioral manifestations, from plain arousal behaviors to alarm reactions with hypermotor features. The semiology and the occurrence pattern of seizures can be explained by an increased propensity to arousal and a dissociation between the partially activated brain and a sleeping (dysfunctional) dorsofrontal cortical system. The clinical semiology of the genetic variations and the sporadic cases does not differ.Therefore, NFLE seems to be linked to the epileptically facilitated cholinergic arousal system, underlain by a genetic or a suspected genetic origin.Arousal parasomnia (AP) manifests behaviors similar to those of NFLE, caused by a nonepileptic mechanism. The two conditions (AP and NFLE) show a familial clustering, with patients and families suffering in both conditions and probably sharing the pathomechanisms related to a dissociation background.We can see that NFLE and AP (the epileptic and nonepileptic counterparts) may both be linked to a disorder of the frontal part of the ascending arousal system.