Training chicks on a passive avoidance task modulates glutamate-stimulated inositol phosphate accumulation

Area of Science:

• Neuroscience
• Biochemistry
• Learning and Memory

Background:

• The intermediate medial hyperstriatum ventrale (IMHV) in chick forebrain is crucial for memory formation.
• Phosphoinositide signaling plays a role in synaptic plasticity and memory consolidation.

Purpose of the Study:

• To investigate the effects of various neurotransmitters and receptor agonists on inositol phosphate (IP) accumulation in the chick IMHV.
• To determine the role of specific glutamate receptors in memory formation after passive avoidance training.

Main Methods:

• Tissue prisms from chick forebrain (IMHV) were used for in vitro studies.
• Measurements of inositol phosphate (IP) accumulation were performed.
• Neurotransmitter effects (glutamate, NMDA, MK801, AMPA, quisqualate) on IP accumulation were assessed.
• Passive avoidance training was conducted, followed by IP accumulation measurements at different time points.

Main Results:

• Quisqualate and AMPA significantly increased IP accumulation in the IMHV, with greater effects in the right hemisphere.
• Glutamate also stimulated IP accumulation, particularly in the left IMHV.
• Passive avoidance training reduced glutamate-stimulated IP accumulation in the left IMHV 30 minutes post-training.
• MK801 abolished this training-induced decrease without affecting basal IP accumulation.

Conclusions:

• Memory formation for passive avoidance tasks in chicks involves NMDA receptor channel activation in the left IMHV.
• The observed changes in IP accumulation are time-dependent and specific to the trained hemisphere.
• These findings suggest a role for NMDA receptor-mediated signaling in the biochemical cascade underlying memory consolidation.