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Updated: Oct 14, 2026
Analysis of Dendritic Spine Morphology in Cultured CNS Neurons
Published on: July 13, 2011
Dendritic spine density in the lobus parolfactorius of the domestic chick is increased 24 h after one-trial passive
1Biology Department, Open University, Milton Keynes, UK.
Insights
Chicks trained to avoid a bitter substance showed increased dendritic spine density in their brains. This brain plasticity in the lobus parolfactorius may relate to long-term memory formation.
Area of Science:
- Neuroscience
- Animal Behavior
- Cell Biology
Background:
- Young chicks naturally peck at small objects.
- Chicks exhibit a learned aversion to objects associated with unpleasant tastes.
Purpose of the Study:
- To investigate the neural mechanisms underlying passive avoidance learning in chicks.
- To examine brain plasticity in the lobus parolfactorius after taste aversion training.
Main Methods:
- A one-trial passive avoidance paradigm using methyl anthranilate (MeA) or water coated beads.
- Behavioral testing for retention of avoidance learning.
- Golgi staining and analysis of dendritic spine density in the lobus parolfactorius.
Main Results:
- MeA-trained chicks demonstrated significant avoidance of the bitter bead.
- Increased dendritic spine density was observed in both left and right lobus parolfactorius of MeA-trained chicks compared to controls.
- No significant differences in dendritic length were found between groups.
Conclusions:
- Passive avoidance training induces substantial plasticity in post-synaptic structures of the chick's lobus parolfactorius.
- This observed brain plasticity is likely associated with long-term information storage and memory consolidation.
Abstract:
One to three day old chicks spontaneously peck at small objects. When presented with a chrome bead coated with the bitter tasting substance methyl anthranilate (MeA), chicks peck once, display a characteristic disgust response and subsequently avoid a similar bead. Chicks that are trained on a water coated bead continue to peck a similar bead on retrial. Twenty four hours after training on this one-trial passive avoidance paradigm, chicks were tested for retention. The brains of chicks displaying the correct behavioural response (> 90%) were removed and the lobus parolfactorius from each hemisphere was dissected from the brain and impregnated using a rapid Golgi technique. Analysis of large multipolar neurones by centrifugal dendritic branch order showed that there were significantly more spines on all orders examined in the left hemispheres of MeA-trained chicks compared to water-trained control chicks. Significantly higher spine densities were also found on 4th and 5th order branches of neurones in the right lobus parolfactorius of MeA-trained chicks compared to water-trained chicks. No significant difference in dendritic length was observed. These results suggest that substantial plasticity occurs in post-synaptic structures in the lobus parolfactorius following passive avoidance training. It is suggested that this plasticity is related to processes involved in long term information storage.
