In the CA1 region of the rat hippocampus, long-term potentiation (LTP) requires the activation of NMDA receptors (NMDARs) and leads to an enhancement of AMPA receptor (AMPAR) function. In neonatal hippocampus, this increase in synaptic strength seems to be mediated by delivery of AMPARs to the synapse. Here we studied changes in surface expression of native AMPA and NMDA receptors following induction of LTP in the adult rat brain. In contrast to early postnatal rats, we find that LTP in the adult rat does not alter membrane association of AMPARs. Instead, LTP leads to rapid surface expression of NMDARs in a PKC- and Src-family-dependent manner. The present study suggests a developmental shift in the LTP-dependent trafficking of AMPA receptors. Moreover, our results indicate that insertion of NMDA receptors may be a key step in regulating synaptic plasticity.

Aged rats are known to have deficits in spatial learning behavior in the Morris water maze. We have found that aged rats also have deficits in NR2B protein expression and that the protein expression deficit is correlated with their performance in the Morris water maze. To test whether this NR2B deficit was sufficient to account for the behavioral deficit, we used antisense oligonucleotides to specifically knock down NR2B subunit expression in the hippocampus of young rats. NR2B antisense treatment diminished NMDA receptor responses, abolished NMDA-dependent long-term potentiation (LTP), and impaired spatial learning. These data demonstrate the important role of NR2B in LTP and learning and memory and suggest a role for reduced NR2B expression in age-related cognitive decline.

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Objective To test the hypothesis suggested by previous studies that subthalamic nucleus (STN) deep brain stimulation (DBS) in patients with PD would affect the activity of both motor and non-motor networks, we applied intraoperative fMRI to patients receiving DBS. Patients and Methods Ten patients receiving STN DBS for PD underwent intraoperative 1.5T fMRI during high frequency stimulation delivered via an external pulse generator. The study was conducted between the dates of January 1, 2013 and September 30, 2014. Results We observed blood oxygen level dependent (BOLD) signal changes (FDR<.001) in the motor circuitry, including primary motor, premotor, and supplementary motor cortices, thalamus, pedunculopontine nucleus (PPN), and cerebellum, as well as in the limbic circuitry, including cingulate and insular cortices. Activation of the motor network was observed also after applying a Bonferroni correction (p<.001) to our dataset, suggesting that, across subjects, BOLD changes in the motor circuitry are more consistent compared to those occurring in the non-motor network. Conclusions These findings support the modulatory role of STN DBS on the activity of motor and non-motor networks, and suggest complex mechanisms at the basis of the efficacy of this treatment modality. Furthermore, these results suggest that, across subjects, BOLD changes in the motor circuitry are more consistent compared to those occurring in the non-motor network. With further studies combining the use of real time intraoperative fMRI with clinical outcomes in patients treated with DBS, functional imaging techniques have the potential not only to elucidate the mechanisms of DBS functioning, but also to guide and assist in the surgical treatment of patients affected by movement and neuropsychiatric disorders.