Linking Topography to Tonotopy in the Mouse Auditory Thalamocortical Circuit

Vanderbilt Kennedy Center for Research on Human Development, Department of Hearing and Speech Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 02/2011; 31(8):2983-95. DOI: 10.1523/JNEUROSCI.5333-10.2011
Source: PubMed


The mouse sensory neocortex is reported to lack several hallmark features of topographic organization such as ocular dominance and orientation columns in primary visual cortex or fine-scale tonotopy in primary auditory cortex (AI). Here, we re-examined the question of auditory functional topography by aligning ultra-dense receptive field maps from the auditory cortex and thalamus of the mouse in vivo with the neural circuitry contained in the auditory thalamocortical slice in vitro. We observed precisely organized tonotopic maps of best frequency (BF) in the middle layers of AI and the anterior auditory field as well as in the ventral and medial divisions of the medial geniculate body (MGBv and MGBm, respectively). Tracer injections into distinct zones of the BF map in AI retrogradely labeled topographically organized MGBv projections and weaker, mixed projections from MGBm. Stimulating MGBv along the tonotopic axis in the slice produced an orderly shift of voltage-sensitive dye (VSD) signals along the AI tonotopic axis, demonstrating topography in the mouse thalamocortical circuit that is preserved in the slice. However, compared with BF maps of neuronal spiking activity, the topographic order of subthreshold VSD maps was reduced in layer IV and even further degraded in layer II/III. Therefore, the precision of AI topography varies according to the source and layer of the mapping signal. Our findings further bridge the gap between in vivo and in vitro approaches for the detailed cellular study of auditory thalamocortical circuit organization and plasticity in the genetically tractable mouse model.

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Available from: Takao K Hensch, May 03, 2015
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    • "e l s e v i e r . c o m / l o c a t e / h e a r e s elucidate the functional divergence from their respective input sources (Llano et al., 2009; Broicher et al., 2010; Theyel et al., 2010; Hackett et al., 2011). "
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    • "Showing visual stimuli in different horizontal and vertical positions (Figures 5D and 5F) allowed us to obtain maps of retinotopy covering multiple visual areas (Figures 5E and 5G), including V1, LM, and AL (Wang and Burkhalter, 2007). Presenting tones of different frequencies (Figure 5H) yielded maps of tonotopy in at least two auditory areas (A1 and AAF) (Hackett et al., 2011) (Figure 5I). "
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    • "The mouse is widely used in auditory physiological research because of its merits as an animal model in auditory cortical studies involving two-photon Ca 2ϩ imaging (Bandyopadhyay et al. 2010; Bathellier et al. 2012; Honma et al. 2013; Issa et al. 2014; Rothschild et al. 2010), voltage-sensitive imaging (Sawatari et al. 2011; Takahashi et al. 2006), anatomical studies (Barkat et al. 2011; Hackett et al. 2011; Hofstetter and Ehret 1992; Horie et al. 2013; Llano and Sherman 2008; Oviedo et al. 2010), genetic manipulation (Barkat et al. 2011; Rotschafer and Razak 2013; Xiong et al. 2012), and behavioral analysis (Tsukano et al. 2011). Accordingly, the attainment of precise knowledge of the AI in mice is essential. "
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