These changes were related to the loss of consciousness during seizures. Specifically, altered connectivities between retrosplenial cortex, anterior thalamus, and hippocampus were reported in the Pentylenetetrazol (PTZ) model of absence epilepsy and during experimental limbic seizures ( Brevard et al. In addition to the widely accepted involvement of sensory cortex and thalamus, association cortex, limbic regions, and basal ganglia form brain circuities remote from this core network, which presumably influence seizure manifestation. 2013 Carney and Jackson 2014) and pediatric patients ( Aarabi et al. Combined electroencephalography (EEG) and functional (f)MRI studies ( Gotman and Pittau 2011) confirmed involvement of similar brain network components in adult ( Moeller et al. The central element in the pathology and specifically in initiation, maintenance, and termination of the characteristic spike-and-wave discharges (SWDs) is the cortico-thalamo-cortical circuitry ( Lüttjohann and Pape 2019). 2020).Ībsence epilepsy is a network disease. Impaired cognition, memory function, and attentional deficits have been reported ( Crunelli et al. Although considered a mild form of epilepsy, absence seizures are associated with long-term behavioral changes and comorbidities. By combining multimodal fMRI data, graph theoretical methods, and electrophysiological recordings, we identified the RS as promising target for modulation of seizure activity and/or comorbidities.Įpilepsy, fMRI, GAERS, graph theory, networks IntroductionĪbsence epilepsy is a nonconvulsive form of epilepsy, accounting for 10–17% of all pediatric epilepsies ( Crunelli and Leresche 2002). A potential role of RS as hub between subcortical and cortical regions in epilepsy was supported by increased numbers of parvalbumin-positive (PV+) interneurons together with enhanced inhibitory synaptic activity and neuronal excitability in pyramidal neurons. Subtle differences were observed for retrosplenial cortex (RS), forming more connections beyond cortex in epileptic rats, and showing a tendency to lateralization during seizures. When comparing between strains, intrathalamic connections were prominent in NEC, on local level represented by higher thalamic strengths and hub scores. Stronger connections between thalamic with limbic regions compared with preseizure state indicated network regularization during seizures.
The most prominent acute change in network organization during seizures was the segregation of cortical regions from the remaining brain. Graph theoretical analysis allowed for the identification of acute and chronic network changes and revealed preserved small world topology before and after seizure onset. Resting state-fMRI was performed to explore brain networks in Genetic Absence Epilepsy Rats from Strasbourg and in nonepileptic controls (NEC) during monitoring of the brain state by simultaneous optical Ca 2+-recordings.