Measurements of bosonic modes in high temperature superconductors provide critical information necessary to decipher the puzzle of the pairing mechanism in the cuprates. In this talk, I will discuss our recent STM investigations of the electron-doped cuprate superconductor Pr_0.88LaCe_0.12CuO_4−δ (PLCCO) (T_c = 24 K). Our spectra reveal superconducting gaps with coherence peaks that disappear above T_c.  In addition, multiple step/peak-like features are observed outside the gap. Such features in STM spectra are suggestive of bosonic excitations that couple strongly to the electrons. The energy scale of our mode is the same as the magnetic resonance mode (spin-excitations) in PLCCO measured by inelastic neutron scattering but is also consistent with a low energy acoustic mode. Additionally, I will show that both the local mode energy and the intensity reveal correlations with the local gap energy scale. The sensitivity of the mode intensity to the energy scale of the onset of the continuum of excitations (2Δ) may indicate an electronic origin rather than phonons. Finally I will discuss this data in the context of neutron scattering and STM measurements on other cuprate compounds.