The purpose of this research is to investigate the relationship between the microbiota of the gastrointestinal system and relative gene expression of miRNAs and mRNAs in the brain. This research utilizes C57BL/6 mice as a control group and BALB/c mice, a strain of mice that demonstrate abnormal social and developmental characteristics, as an experimental group. The mice are divided into four groups, a control group for each mouse strain and a probiotic group for each mouse strain. The control groups are fed a bacterial media as a negative control and the experimental groups are fed Bifidobacterium longum. This bacterial species is a well‐characterized probiotic shown to change behavior and improve sociability of BALB/c mice. The mice were fed probiotic bacteria or media control daily for three weeks. To determine the effects on gene expression in the brain the mice were sacrificed and the RNA was extracted from whole brains. Both general and neurological PCR arrays were performed to determine changes in the gene expression of brain‐specific miRNAs. The results of these PCR arrays reveal that the relative gene expression of miR‐652 in the BALB/c mice is substantially more similar to the miRNA’s expression in C57BL/6 only following the B. longum probiotic treatment. qPCR was completed on miR‐652 and on Dab1, an mRNA target of this miRNA. The final goal of this study is to further understand the relationship between changes in gut microbiota and its impacts on neurological gene expression and brain function.