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Passive avoidance learning in the day-old chick is modulated by GABAergic agents
1Biology Department, Open University, Milton Keynes, UK. M.P.Clements@open.ac.uk
Insights
This study investigated memory formation in chicks using drug injections into the brain. Muscimol impaired memory, while bicuculline enhanced memory retention in a passive avoidance task.
Area of Science:
- Neuroscience
- Animal Behavior
- Learning and Memory
Background:
- The intermediate medial hyperstriatum ventrale (IMHV) is crucial for memory formation.
- The GABAergic system's role in memory is not fully understood.
- Passive avoidance tasks are used to study learning and memory.
Purpose of the Study:
- To investigate the role of the GABAergic system in the IMHV on passive avoidance learning and memory retention in day-old chicks.
- To determine the effects of muscimol (GABA agonist) and bicuculline (GABA antagonist) on memory.
Main Methods:
- Day-old chicks were injected with saline, muscimol, or bicuculline into the IMHV.
- Birds were trained on a passive avoidance task using aversive beads (methyl anthranilate or quinine).
- Memory retention was tested at various time points (10 min, 30 min, 24 h).
Main Results:
- Muscimol injections resulted in amnesia, with birds pecking the test bead.
- Bicuculline injections enhanced memory retention, leading to improved avoidance scores at 24 h.
- These findings indicate differential effects of GABAergic modulation on memory acquisition and retention.
Conclusions:
- The GABAergic system in the IMHV plays a significant role in the acquisition and retention of passive avoidance learning.
- Modulation of GABAergic neurotransmission can lead to amnesia or enhanced memory.
- This research provides insights into the neurobiological mechanisms underlying memory processes.
Abstract:
Injection of drugs directly into the intermediate medial hyperstriatum ventrale (IMHV) of day-old chicks, prior to training on a chrome bead dipped in either the strong aversant methyl anthranilate (MeA), or the weak aversant quinine, allows investigation of the effects of potential amnestic and memory-enhancing agents on retention of a passive avoidance task. Chicks were injected into the left and right IMHV, with either saline or muscimol (GABA agonist), 30 minutes before training on an MeA-coated bead. On test, either 10 min, 30 min or 24 h after training, birds were presented with a dry chrome bead. Normally, trained birds will avoid the test bead; however, significantly more muscimol-injected birds pecked the dry bead than did saline-injected chicks, indicating amnesia in the muscimol-injected birds. In chicks injected bilaterally into the IMHV with bicuculline, a GABAA antagonist, 30 minutes prior to training on a quinine-coated bead, avoidance scores were significantly improved on testing at 24 h compared with saline-injected control chicks, indicating enhanced retention in bicuculline-treated birds. These results suggest a role for the GABAergic system in the acquisition and retention of passive avoidance learning in the day-old chick.