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J Vis Exp. 2016 May 21;(111). doi: 10.3791/53914.

Extracellular Recording of Neuronal Activity Combined with Microiontophoretic Application of Neuroactive Substances in Awake Mice.

Author information

1
Auditory Neuroscience Laboratory, Institute of Neuroscience of Castilla y León, University of Salamanca.
2
Auditory Neuroscience Laboratory, Institute of Neuroscience of Castilla y León, University of Salamanca; Neural Systems Laboratory, Institute for Systems Research, University of Maryland.
3
Medical Research Council Institute of Hearing Research.
4
Auditory Neuroscience Laboratory, Institute of Neuroscience of Castilla y León, University of Salamanca; Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca; msm@usal.es.

Abstract

Differences in the activity of neurotransmitters and neuromodulators, and consequently different neural responses, can be found between anesthetized and awake animals. Therefore, methods allowing the manipulation of synaptic systems in awake animals are required in order to determine the contribution of synaptic inputs to neuronal processing unaffected by anesthetics. Here, we present methodology for the construction of electrodes to simultaneously record extracellular neural activity and release multiple neuroactive substances at the vicinity of the recording sites in awake mice. By combining these procedures, we performed microiontophoretic injections of gabazine to selectively block GABAA receptors in neurons of the inferior colliculus of head-restrained mice. Gabazine successfully modified neural response properties such as the frequency response area and stimulus-specific adaptation. Thus, we demonstrate that our methods are suitable for recording single-unit activity and for dissecting the role of specific neurotransmitter receptors in auditory processing. The main limitation of the described procedure is the relatively short recording time (~3 hr), which is determined by the level of habituation of the animal to the recording sessions. On the other hand, multiple recording sessions can be performed in the same animal. The advantage of this technique over other experimental procedures used to manipulate the level of neurotransmission or neuromodulation (such as systemic injections or the use of optogenetic models), is that the drug effect is confined to the local synaptic inputs to the target neuron. In addition, the custom-manufacture of electrodes allows adjustment of specific parameters according to the neural structure and type of neuron of interest (such as the tip resistance for improving the signal-to-noise ratio of the recordings).

PMID:
27286308
PMCID:
PMC4927710
DOI:
10.3791/53914
[Indexed for MEDLINE]
Free PMC Article

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