Method Article

Functionele Beeldvorming van de auditieve cortex in volwassen katten met behulp van High-field fMRI

DOI:

10.3791/50872

⸱

February 19th, 2014

 ,  ,  ,  ,  , 
1Department of Physiology and Pharmacology, University of Western Ontario, 2Department of Psychology, University of Western Ontario, 3Department of Medical Biophysics, University of Western Ontario, 4Brain and Mind Institute, University of Western Ontario, 5Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, 6Cerebral Systems Laboratory, University of Western Ontario, 7National Centre for Audiology, University of Western Ontario

In This Article

Summary

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Functional studies of the auditory system in mammals have traditionally been conducted using spatially-focused techniques such as electrophysiological recordings. The following protocol describes a method of visualizing large-scale patterns of evoked hemodynamic activity in the cat auditory cortex using functional magnetic resonance imaging.

Abstract

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

De huidige kennis van sensorische verwerking in het auditief systeem van zoogdieren is voornamelijk afkomstig van elektrofysiologische studies in verschillende diermodellen, zoals apen, fretten, knuppels, knaagdieren en katten. Om geschikte parallellen tussen menselijke en dierlijke modellen van gehoorfunctie trekken, is het belangrijk om een ​​brug tussen menselijke functionele beeldvorming studies en dierlijke elektrofysiologische studies stellen. Functionele magnetische resonantie imaging (fMRI) is een gevestigde, minimaal invasieve methode voor het meten brede patronen van hemodynamische activiteit in verschillende gebieden van de cerebrale cortex. Deze techniek wordt veel gebruikt voor sensorische functie in het menselijk brein sonde is een nuttig instrument koppelen studies auditieve verwerking bij mens en dier en is met succes gebruikt om gehoorfunctie bij apen en knaagdieren onderzoeken. Het volgende protocol beschrijft een experimentele procedure voor het onderzoeken van auditieve functie in verdoofde volwassenkatten door het meten-stimulus opgeroepen hemodynamische veranderingen in de auditieve cortex met behulp van fMRI. Deze methode maakt vergelijking van de hemodynamische responsen in verschillende modellen gehoorfunctie hetgeen leidt tot een beter begrip van species-onafhankelijke eigenschappen van de zoogdieren auditieve cortex.

Introduction

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Current understanding of auditory processing in mammals is mainly derived from invasive electrophysiological studies in monkeys1-5, ferrets6-10, bats11-14, rodents15-19, and cats20-24. Electrophysiological techniques commonly utilize extracellular microelectrodes to record the activity of single and multiple neurons within a small area of neural tissue surrounding the electrode tip. Established functional imaging methods, such as optical imaging and functional magnetic resonance imaging (fMRI), serve as useful complements to extracellular recordings by providing a macroscopic perspective of simultaneous driven act....

Access restricted. Please log in or start a trial to view this content.

Protocol

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

The following procedure can be applied to any imaging experiment in which anesthetized cats are used. Steps which are specifically required for auditory experiments (steps 1.1-1.7, 2.8, 4.1) can be modified to accommodate other sensory stimulus protocols.

All experimental procedures received approval from the Animal Use Subcommittee of the University Council on Animal Care at the University of Western Ontario and followed the guidelines specified by the Canadian Council on Animal Care (CCAC)44. The outlined experiment requires approximately 150 min from animal preparation to recovery. The time course of the experiment is illustra....

Access restricted. Please log in or start a trial to view this content.

Results

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Representative functional data were acquired in a 7T horizontal bore scanner and analyzed using the Statistical Parametric Mapping toolbox in MATLAB. Robust cortical hemodynamic responses to auditory stimulation have consistently been observed in cats using the described experimental protocol43. Figure 6 illustrates the BOLD activation in 2 animals in response to a 30 sec broadband noise stimulus presented in a block design. T-statistic maps of the broadband noise vs. baseline (no stimulus) co.......

Access restricted. Please log in or start a trial to view this content.

Discussion

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

In designing an fMRI experiment for an anesthetized animal model of auditory function, the following issues should be given careful consideration: (i) the impact of anesthesia on cortical responses, (ii) the effect of background scanner noise, and (iii) the optimization of the data collection phase of the experimental procedure.

While an anesthetized preparation offers the important advantage of producing a prolonged period of sedation and minimizing potential head motion during a functional i.......

Access restricted. Please log in or start a trial to view this content.

Disclosures

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

The authors declare no conflicts of interest, financial or otherwise.

Acknowledgements

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

The authors would like to acknowledge the contributions of Kyle Gilbert, who designed the custom RF coil, and Kevin Barker, who designed the MRI-compatible sled. This work was supported by the Canadian Institutes of Health Research (CIHR), Natural Sciences and Engineering Research Council of Canada (NSERC), and Canada Foundation for Innovation (CFI).

....

Access restricted. Please log in or start a trial to view this content.

Materials

List of materials used in this article
NameCompanyCatalog NumberComments
Materials
Atropine sulphate injection 0.5 mg/mlRafter 8 Products
Acepromazine 5 mg/mlVetoquinol Inc.
Ketamine hydrochloride 100 mg/mlBimeda-MTC
Dexmedetomidine hydrochloride (Dexdomitor 0.5 mg/ml)Orion Pharma
Isoflurane 99.9%Abbott Laboratories
Lidocaine (Xylocaine endotracheal 10 mg/metered dose)Astra Zeneca
Lubricating opthalmic ointment (Refresh Lacri Lube)Allergan Inc.
Saline 0.95%
IV Catheter 22 g (wings)
IV Extension SetCodan US Corp.BC 269
IV Administration Set 10 drips/ml
Endotracheal tube 4.0
Heating pads (Snuggle Safe)Lenric C21 Ltd.
Syringe 60 ml
Equipment
External sound cardRoland CorporationCakewalk UA-25EX
Stereo power amplifierPyle Audio Inc.Pyle Pro PCAU11
MRI-compatible insert earphone systemSensimetric CorporationModel S14
Foam ear tips for insert earphonesE-A-R Auditory SystemsEarlink 3B
End-tidal CO2 monitorNellcorN-85
MRI-compatible pulse oximeterNonin Medical Inc.Model 7500
Syringe pumpHarvard Apparatus70-2208

References

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,
  1. Kaas, J. H., Hackett, T. A. Subdivisions of auditory cortex and processing streams in primates. Proc. Natl. Acad. Sci. U.S.A. 97, 11793-11799 (2000).
  2. Kusmierek, P., Rauschecker, J. P. Functional Specialization of Medial Auditory Belt Cortex inthe Ale....

Access restricted. Please log in or start a trial to view this content.

Reprints and Permissions

Request permission to reuse the text or figures of this JoVE article

Request Permission

Tags

Auditory Cortex ImagingFunctional MRIHigh field fMRIAnesthetized CatsAuditory StimulusHemodynamic ResponseBrain ActivationMRI Compatible SledKetamine AnesthesiaSPM FSL Analysis

Related Articles