A comparative analysis of mouse and human medial geniculate nucleus connectivity: A DTI and anterograde tracing study

Abstract

Understanding the function and connectivity of thalamic nuclei is critical for understanding normal and pathological brain function. The medial geniculate nucleus (MGN) has been studied mostly in the context of auditory processing and its connection to the auditory cortex. However, there is a growing body of evidence that the MGN and surrounding associated areas (‘MGN/S’) have a diversity of projections including those to the globus pallidus, caudate/putamen, amygdala, hypothalamus, and thalamus. Concomitantly, pathways projecting to the medial geniculate include not only the inferior colliculus but also the auditory cortex, insula, cerebellum, and globus pallidus. Here we expand our understanding of the connectivity of the MGN/S by using comparative diffusion weighted imaging with probabilistic tractography in both human and mouse brains (most previous work was in rats). In doing so, we provide the first report that attempts to match probabilistic tractography results between human and mice. Additionally, we provide anterograde tracing results for the mouse brain, which corroborate the probabilistic tractography findings. Overall, the study provides evidence for the homology of MGN/S patterns of connectivity across species for understanding translational approaches to thalamic connectivity and function. Further, it points to the utility of DTI in both human studies and small animal modeling, and it suggests potential roles of these connections in human cognition, behavior, and disease.

An Integrated Assessment of Changes in Brain Structure and Function of the Insula Resulting from an Intensive Mindfulness-Based Intervention

“…First, the posterior insula is densely connected to both the thalamus and auditory cortex (Jones & Burton 1976;Mesulam & Mufson 1985;Keifer, Gutman, Hecht, Keilholz, & Ressler 2015). Second, the latency of posterior insula responses to auditory evoked potentials is consistent with direct connections from the medial geniculate nucleus of the thalamus, suggesting that the posterior insula receives auditory information in the early stages of sensory processing (Sudakov, McLean, Reeves, & Marino 1971;Guldin & Markowitsch 1984;Keifer et al 2015).…”

Sensorineural hearing loss and cognitive impairments: Contributions of thalamus using multiparametric MRI

“…As a paired deep structure in the brain, the thalamus is traditionally conceptualized as a sensory hub and a substantial amount of information coming into the cortex does so through the thalamus . In the traditional auditory pathway, the medial geniculate body (part of the auditory thalamus) has been well‐researched and represents the relay between the inferior colliculus and auditory cortex . Emerging evidence has also linked the thalamus to cognition via thalamocortical radiations, suggesting that the thalamus is the key structure in cognition processing, including memory, attention, and executive control .…”

Heritability of the Mouse Brain Connectome

“…Experimental genetic studies that have used many of these MRI methods have been limited by the technical difficulties of scaling from the human brain (950-1800 cm3) down to the mouse brain (0.32-0.52 cm3) [7][8][9]. Routine rodent brain connectomics is challenging because of the simultaneous demands of 1) reducing voxel volume by a factor of 3000, 2) providing sufficient diffusion weighting, 3) sampling an adequate number of gradient angles, 4) maintaining good signal-to-noise ratios, and 5) maintaining a reasonable scan time of less than 24 h per brain.…”