title: There's more than one way to scan a cat: imaging cat auditory cortex with high-field fMRI using continuous or sparse sampling.
abstract: When conducting auditory investigations using functional magnetic resonance imaging (fMRI), there are inherent potential confounds that need to be considered. Traditional continuous fMRI acquisition methods produce sounds >90 dB which compete with stimuli or produce neural activation masking evoked activity. Sparse scanning methods insert a period of reduced MRI-related noise, between image acquisitions, in which a stimulus can be presented without competition. In this study, we compared sparse and continuous scanning methods to identify the optimal approach to investigate acoustically evoked cortical, thalamic and midbrain activity in the cat. Using a 7 T magnet, we presented broadband noise, 10 kHz tones, or 0.5 kHz tones in a block design, interleaved with blocks in which no stimulus was presented. Continuous scanning resulted in larger clusters of activation and more peak voxels within the auditory cortex. However, no significant activation was observed within the thalamus. Also, there was no significant difference found, between continuous or sparse scanning, in activations of midbrain structures. Higher magnitude activations were identified in auditory cortex compared to the midbrain using both continuous and sparse scanning. These results indicate that continuous scanning is the preferred method for investigations of auditory cortex in the cat using fMRI. Also, choice of method for future investigations of midbrain activity should be driven by other experimental factors, such as stimulus intensity and task performance during scanning.
authors.affiliation: Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C2, Canada; Cerebral Systems Laboratory, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Amee J
authors.initials: AJ
authors.lastname: Hall
authors.affiliation: Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario N6A 5C2, Canada; Cerebral Systems Laboratory, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Trecia A
authors.initials: TA
authors.lastname: Brown
authors.affiliation: Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Ontario N6A 5C2, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Grahn
authors.affiliation: Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada; Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Gati
authors.affiliation: Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario N6A 5C2, Canada; Cerebral Systems Laboratory, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Pam L
authors.initials: PL
authors.lastname: Nixon
authors.affiliation: Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Hughes
authors.affiliation: Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada; Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Ravi S
authors.initials: RS
authors.lastname: Menon
authors.affiliation: Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario N6A 5C2, Canada; Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Ontario N6A 5C2, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario N6A 5C2, Canada; Cerebral Systems Laboratory, University of Western Ontario, London, Ontario N6A 5C2, Canada; National Centre for Audiology, University of Western Ontario, London, Ontario N6A 5C2, Canada. Electronic address: steve.lomber@uwo.ca.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Lomber
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001931:Brain Mapping; D002415:Cats; D005260:Female; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D010100:Oxygen / Q000097:blood; D011571:Psychoacoustics; D014793:Visual Cortex / Q000098:blood supply* / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: 7-Tesla; Broadband noise; Inferior colliculus; Thalamus; Tonal stimulation