Epicranial sensory evoked potential recordings for repeated assessment of cortical functions in mice

In the present study, we describe a simple and minimally invasive method to record sensory evoked potentials (SEP) in the anesthetized mouse. The hard ware includes a 16-channel acquisition system with a high signal/noise rati o and high temporal resolution. Under general anesthesia the skull is expos ed and stainless steel electrodes are placed directly over the bone. A comp uter controlled electromechanical stimulation is applied to a single whiske r or a group of whiskers unilaterally and cortical responses are recorded b ilaterally. Primary SEP are detected over the contralateral barrel cortex, but delayed signals appear over the motor cortex, secondary somatosensory c ortex and the ipsilateral hemisphere. The size of evoked SEP correlates wit h the number of stimulated whiskers and responses are reproducible and cons istent over time when recorded repeatedly for up to 6 weeks. We conclude th at epicranial multichannel recording of SEP represents an interesting, mini mally invasive approach to monitor repeatedly cortical activity and study c ertain aspects of long-term plasticity of evoked responses in mice. (C) 200 0 Elsevier Science B.V. All rights reserved.