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Specificity of Basal Forebrain Cholinergic Neuron Cell Growth on Hippocampal Formation
Irene Tsai
Mentor: Richard Robertson
Neurons communicate by sending axons to synapse with dendrites of target neurons. The cell to cell
interactions of neurons in the brain form the basis of establishing connections in the nervous system.
However, the exact mechanism of how synaptic connections are formed is still not fully understood.
In order to study this mechanism, our laboratory studies basal forebrain cholinergic neuron
projections to the dentate gyrus of the hippocampus as our model system. Our laboratory has
developed a technique in which basal forebrain neurons are dissociated and “seeded” onto cultured
slices of hippocampus. Past experiments have shown that cholinergic neurons of the basal forebrain
do form a specific pattern in the dentate gyrus of the hippocampus. The goal of this experiment is to
determine whether non-cholinergic neurons also form a specific pattern or whether they display a
random distribution. We use BrdU, a cell birthdate marker, which labels cholinergic as well as noncholinergic basal forebrain neurons. To carry out the experiment, we cut organotypic slices from P68 rat pups and sprinkle dissociated basal forebrain onto them. Then, we visualize the cells using
BrdU immunocytochemistry. Preliminary results have shown that BrdU labeled cells form a random
array rather than a specific pattern. Because the cholinergic neurons are less than 10% of all the total
neurons, we may not be able to easily detect their specific pattern within the random pattern of all
neurons. Future experiments could involve staining only non-cholinergic neurons to verify if they do
indeed grow in a random array.