Using MEG to map the auditory cortex. Jonathan Côté PhD Candidate in Etienne de Villers-Sidani s laboratory

Transcription

1 Using MEG to map the auditory cortex Jonathan Côté PhD Candidate in Etienne de Villers-Sidani s laboratory

2 Sensory representations organization

3 Sensory representations organization Organized map for most senses Sensorimotor system (Previous slide) Visual system: Retinotopy Auditory system: Tonotopy

4 Primary auditory cortex Characteristics of interest 1. Naturally aging develops auditory processing deficits such as neurons in the aged brain have abnormally broad and less specific tuning characteristics. 2. Tonotopic maps are modified when attention-demanding intensive training strategies are used 3. Primary and secondary auditorycortex tonotopic maps exhibit enlargement of target sound frequency range when rats were trained to attend to frequency cues de Villers-Sidani et al., 2010

5 Questions How is this map is dynamically modulated? What regions are responsible for modifying this map? How does learning differs through age?

6 Human model o Multiple, whole-brain recording Not fmri Why MEG? o Instinctive reason: Very loud o High temporal resolution is needed. Not EEG o Mapping by definition needs good spatial resolution First step: Can we obtain a Tonotopic map with MEG?

7 Experimental design Day Training + Home Training + Home Training + Home MEG training MEG training MEG training mapping recording recording Day Home Home Training + Home Home Training + training training MEG training training MEG recording mapping Two stimuli needed: The auditory training and the mapping

8 Experimental design: Training

9 Experimental design: Mapping stimulus Multiple frequencies, same intensity Different densities Warning: Be mindful of the transducer s sound range o Also aged participants

10 Initial mapping analysis A B Source space For each frequency, average activity following for each single vertex Vertex Frequency #1 Frequency #2 A 4 7 B 5 3 A B 100 Vertices x 20 Frequencies

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12 Reverse correlation analysis A Source space one vertex at the time Events (On 10 mins of stim) Look back at what sound was played Count the occurrence and timing of each sound frequency.

13 Spectro-temporal receptive fields Vertex A Occurrence and amplitude Repeat on all vertices Vertex B Vertex C

14 MEG Tonotopic maps Subject 1 Subject 2 Subject 3 Subject 4 Average

15 Next steps More data can be extracted Questions Tonotopic map can be obtained through MEG What is the effect of learning of these map? How does learning differ through age?

16 Bibliography OpenStax College - Anatomy & Physiology, Connexions Web site. Jun 19, Osler Library of the History of Medecine. McGill University, Photography Collection. Hearing, Faraz Tak, Internship at Dr. Jose R. Reyes Memorial Medical Center, LinkedIn.com slide shate Changes of AI Receptive Fields With Sound Density David T. Blake, Michael M. Merzenich Journal of Neurophysiology Published 1 December 2002 Vol. 88 no. 6, Recovery of functional and structural age-related changes in the rat primary auditory cortex with operant training. de Villers-Sidani E1, Alzghoul L, Zhou X, Simpson KL, Lin RC, Merzenich MM. Proc Natl Acad Sci U S A Aug 3;107(31)

17 McConnell Brain Imaging Center Elizabeth Bock Jean-Pierre Falet Undergraduate helpers Anthea Zeng Lucy Karp Dr Marilyn Jones-Gotman Dr Gabriel Leonard Dr Benjamin Zendel Sebastien Dery Soheila Samiee