Nuclear isomers impact a broad range of scientific and technical fields, from radio-medicine to stellar nucleosynthesis. Direct manipulation of isomer populations can enable a powerful new technique for mitigating spent-nuclear fuel, as well as enable new approaches to nuclear batteries. This work introduces a novel technique for the direct manipulation of isomer populations utilizing the enhanced nuclear level density (NLD) at high excitation energies, known as the nuclear quasicontinuum. Following excitation into the quasicontinuum, additional coupling of spin can occur through real or virtual photon transfer mediated by nuclear-plasma interactions (NPIs). Laser-plasma accelerators (LPAs) provide energetic, ultra-short pulse electron beams. This work discusses an experimental proof-of-concept study of manipulating isomer populations in Bromine nuclei using LPA-sourced $<100$ fs electron beams. A comparison of bremsstrahlung photon and electron irradiation cases is evaluated to determine the presence of electron-nuclear interaction contributions to isomer populations. Additionally, the potential for LPAs to be used as sensitive probes of NLD models and photon strength functions in an effort to characterize the nuclear quasicontinuum is explored.