Projections | Study | Model | Stimulation pattern | Main findings |
All | Mamad 2015 | Rats | Theta burst | Resets the spiking of hippocampal theta cells, increases theta synchronisation, entrains the spiking of hippocampal place cells |
Cholinergic neurons and/or projections Optogenetic excitation | Van der Casteele et al 2014 | Mice, with or without urethane anaesthesia | Sine wave, 1–12 Hz | Enhance theta rythm, suppress peri-theta frequency bands |
Dannenberg et al 2015 | Mice, under urethane anaesthesia | Square pulses, 5–40 Hz | Increase firing of hippocampal inhibitory interneurons and decrease firing of principal cells Their activation is required for theta synchronisation | |
Mamad et al 2015 | Rats, awake | Square pulses, 8–10 Hz vs 50 Hz | The most potent effect on hippocampal theta amplitude was observed after 8–10 Hz stimulation and in a non-active behavioural state | |
GABAergic neurons and/or projections Optogenetic excitation | Gangadharan et al 2016 | Mice, freely moving | Square pulses, 10 or 20 Hz | Enhance type 2 theta rhythm, object exploration and not open-field exploration behaviour |
Glutamatergic neurons and/or projections Optogenetic excitation | Fuhrmann et al 2015 | Mice, freely moving | 3–12 Hz | Enable initiation of locomotion and theta oscillations as well as the active regulation of locomotion speed |
Robinson et al 2016 | Mice, freely moving | 4–12 Hz | MS glutamatergic neurons synchronise hippocampal theta rhythms whereas activation of their projections to the hippocampus through fornix stimulations has no effect on theta rhythms |
MS, medial septum.