Morphological changes in the dentate gyrus in human temporal lobe epilepsy

Area of Science:

• Neuroscience
• Epilepsy Research
• Human Neuroanatomy

Background:

• The dentate gyrus, a key component of the hippocampal formation, exhibits significant alterations in temporal lobe epilepsy (TLE).
• Previous research has identified neuronal loss and reorganization within the dentate gyrus in TLE patients.

Purpose of the Study:

• To discuss three distinct types of morphological and neurochemical changes in the dentate gyrus of humans with TLE.
• To explore potential interrelationships between these observed changes.
• To understand how these alterations might influence seizure susceptibility.

Main Methods:

• Review and synthesis of existing literature on morphological and neurochemical changes in the human dentate gyrus in TLE.
• Analysis of documented cases of TLE with specific attention to neuronal loss, afferent reorganization, and granule cell layer disorganization.

Main Results:

• Documented neuronal loss, particularly in hilar neurons, in severe TLE cases.
• Observed reorganization of afferents, including aberrant mossy fiber innervation within the dentate gyrus molecular layer.
• Identified disorganization of the granule cell layer, including dispersed or bilaminar patterns in a subpopulation of TLE specimens.

Conclusions:

• The discussed changes—neuronal loss, mossy fiber reorganization, and granule cell disorganization—collectively contribute to altered dentate gyrus circuitry in TLE.
• These circuit alterations are hypothesized to play a role in the increased seizure susceptibility characteristic of temporal lobe epilepsy.