Table 1.

Summary findings after mossy cell-selective neurodegeneration.

	Acute phase (4–11 days)	Chronic phase (~6 weeks)	Comments
Morphology	No obvious change except mossy cell degeneration	No mossy fiber sprouting; GABAergic sprouting at IML	Mossy cell loss triggers no mossy fiber sprouting
sEPSC and sIPSC from granule cell	Frequencies both reduced	Back to normal level	Transient reduction of both excitatory and inhibitory input to granule cell
In vitro perforant path stimulation	Hyperexcitable granule cell	Back to normal level	Net inhibitory role of mossy cell in granule cell activity
Kainate-induced IEG expression	Increase in c-Fos and Zif268	No change	Associated with hyper-excitable granule cell
Kainate-induced seizure	More susceptible	No change	Possibly due to hyper-excitable granule cell
In vivo LFP recording	No epileptiform discharge	No epileptiform discharge	Mossy cell loss insufficient for spontaneous epilepsy
	Theta power enhanced during exploration	Back to normal level	Possibly due to hyper-excitable granule cell
Behavior	No behavioral seizure	No behavioral seizure	Mossy cell loss insufficient for spontaneous seizure
	Increased anxiety	Back to normal level	Possibly due to hyper-excitable granule cell
	Impaired contextual discrimination	Back to normal level	Possibly due to hyper-excitable granule cell

IEG, immediate early gene; IML, inner molecular layer; LFP, local field potential; sEPSC, spontaneous excitatory postsynaptic current; sIPSC, spontaneous inhibitory postsynaptic current.