Mismatch negativity (MMN) is an event related potential (ERP) component representing the pre-attentive process of deviance detection. In line with broad sensory processing deficits in several neuropsychiatric as well as neurological disorders, MMN is affected in among others schizophrenia, autism and migraine [1,2]. Sensory processing deficits have been found over all sensory domains, however MMN research has greatly focused on auditory processing. Visual MMN has been studied in a number of human studies, but only once in a rodent study, in which mice were head-fixated . To reduce stress and enhance behavioural relevance, we here developed a visual MMN set-up in which mice could behave freely.
Epi-dural electrodes were placed on top of the primary visual cortex (V1) for tethered EEG recordings in a LED-illuminated sphere in which mice could move around freely. An oddball paradigm with 12,5% deviant stimuli was presented. Standard and deviant stimuli were white light flashes with either high or low light intensity. MMN was assessed from the difference waves of averaged ERP responses (deviant – standard).
Using this novel approach, we were able to measure a visual MMN in freely moving mice. In difference waves from high intensity stimuli, a biphasic negativity was found that differed significantly from zero. Based on the latencies and literature, the first period of negativity might represent sensory adaptation of the N1, while the second period could represent true deviance detection. For the low intensity stimuli, only the second phase reached significance.
Interest for sensory processing deficits in neurological and neuropsychiatric disorders is growing vastly. Using MMN, higher order pre-attentive sensory processes can be studied easily in various disease models. This paradigm could therefore provide a useful approach to study neurobiological mechanisms and to further our understanding of visual processing deficits in multiple neurological and neuropsychiatric disorders.
Keywords: Mismatch negativity, Visual processing, Neuropsychiatric disorders, Oddball paradigm
|Event title||20th Biennial International Pharmaco-EEG Society Meeting: null|
|Degree of Recognition||International|