• CCK-8-treated mice fail to exhibit a change in AMPA excitatory postsynaptic currents unlike in similarly treated wild-type mice

• in a Morris water maze, standard housed and environmentally enriched mice fail to exhibit a preference for the target quadrant unlike similarly treated wild-type mice

• in a Morris water maze, standard housed exhibit decreased frequency of crossing over the platform and increased latency compared with wild-type mice

• mice in standard housing exhibit decreased startle reflex compared with wild-type mice in standard housing

• environmental enrichment fails to decrease startle reflex as in similarly treated wild-type mice

• however, clozapine attenuates startle reflex as in wild-type mice

• mice in standard housing exhibit hypoactivity compared with wild-type mice in standard housing

• however, mice exposed to environmental enrichment exhibit normal activity levels

• mice in standard housing exhibit decreased prepulse inhibition compared with wild-type mice in standard housing

• however, environmental enrichment or treatment with clozapine rescue prepulse inhibition deficit

• most mice died at the age of 3 weeks

• hypersensitivity to epileptogenic drugs (metrazol and kainic acid)

• exhibited prior to 3 wks of age

• tonic-clonic or tonic extension of the whole body

• putatively evoked by hippocampal hyperexcitability

• hypersensitivity to epileptogenic drugs (metrazol and kainic acid)

• exhibited prior to 3 wks of age

• tonic-clonic or tonic extension of the whole body

• putatively evoked by hippocampal hyperexcitability

• loss of somatostatin-containing neurons, putatively resulting in hippocampal hyperexcitability leading to seizures