Methamphetamine (METH) abuse is quickly becoming an epidemic in both the United States and the world. One symptom of METH use is stereotypic behavior, or repetitive, non-goal oriented behaviors that interfere with goal directed behaviors. Investigators have looked at the striatum for the formation of these behaviors since ritualistic behaviors are defining characteristics of this region. The ventral striatum is associated with limbic circuits while the dorsal striatum is linked to motor circuits. Within these regions lie two additional subregions, the patch and the matrix. The patch receives predominantly limbic inputs while the matrix has predominately sensorimotor inputs. Previous work has determined that the patch region of the dorsal striatum is responsible for the formation of stereotypic behavior, but the precise mechanism remains unclear. We hypothesized that these behaviors arise from synaptic plasticity occurring in the patch and matrix regions of the dorsal striatum. Chronic METH was given to rats and electrophysiology was used to determine changes in excitatory synaptic strength in neurons within this brain region. Although we did not find any statistically significant difference when comparing the patch and matrix neurons of saline and chronic METH treated animals respectively, we did see a trend towards long term potentiation in chronic METH patch treated neurons. More studies will need to be done to increase the sample size and determine if the synaptic changes are long-term or short-term in nature.
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