Partial limbic kindling--brain, behavior, and the benzodiazepine receptor

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Neuropharmacology

Background:

• Partial kindling (PK) of the perforant path (PP) is a model for studying lasting behavioral changes.
• Long-term potentiation (LTP) in specific brain pathways is associated with behavioral alterations.

Purpose of the Study:

• To investigate the lasting effects of partial kindling on feline defensiveness.
• To examine the role of amygdala and hippocampal pathways in kindling-induced behavioral changes.
• To determine the effects of flumazenil on kindling-related behaviors and neural plasticity.

Main Methods:

• Partial kindling of the left perforant path (PP) in felines.
• Electrophysiological recordings to assess long-term potentiation (LTP) in amygdala-ventromedial hypothalamic (AM-VMH) and ventroamygdalofugal (VAF)-VMH pathways.
• Measurement of CA3 recurrent inhibition and excitability changes in the periaqueductal grey.
• Administration of flumazenil to assess its effects on defensive behavior and LTP.

Main Results:

• Perforant path PK induced lasting defensiveness and LTP in AM-VMH pathways and VAF-VMH efferents.
• LTP in AM-VMH pathways paralleled behavioral changes, while CA3 LTP preceded them.
• Flumazenil dose-dependently reduced defensive responses and AM-VMH LTP, but not VAF-VMH LTP.
• Flumazenil's effects suggest action within the amygdala.

Conclusions:

• Partial kindling induces lasting behavioral and neuroplastic changes.
• The amygdala plays a crucial role in mediating kindling-induced defensiveness and LTP.
• Flumazenil acts as an agonist on behavior and in the amygdala following kindling.