Grey matter heterotopia subtypes show specific morpho-electric signatures and network dynamics

Area of Science:

• Neuroscience
• Developmental Biology
• Epileptology

Background:

• Grey matter heterotopia (GMH) are neurodevelopmental disorders characterized by misplaced neurons, leading to abnormal cortical function and epilepsy.
• Subcortical band heterotopia (SBH) and periventricular nodular heterotopia (PVNH) are distinct subtypes of GMH, differing in neuronal organization.
• The precise pathological consequences and shared mechanisms underlying epilepsy in SBH and PVNH remain incompletely understood.

Purpose of the Study:

• To systematically compare the physiological and morphological properties of neurons in preclinical models of SBH and PVNH.
• To investigate the dynamics of epileptiform activity and input connectivity in these distinct GMH subtypes.
• To determine whether GMH subtypes share common altered mechanisms or exhibit subtype-specific pathological consequences.

Main Methods:

• Utilized two established preclinical models representing SBH and PVNH.
• Conducted a comparative assessment of heterotopia neuron physiology and morphology.
• Analyzed the dynamics of epileptiform activity and neuronal input connectivity.

Main Results:

• Identified a complex array of altered neuronal properties, with both shared and distinct features across SBH and PVNH subtypes.
• Observed subtype-specific dynamics of epileptiform activity correlated with neuronal properties.
• Demonstrated that pro-epileptic circuits in GMH involve neurons with distinct, subtype-specific, morpho-electric characteristics.

Conclusions:

• GMH represent a heterogeneous group of disorders with both common and divergent pathological consequences.
• Epileptogenic networks in GMH are shaped by subtype-specific neuronal properties.
• Identifying morpho-electric signatures of GMH subtypes may refine classification and inform novel therapeutic strategies.