Subcortical input heterogeneity in the mouse inferior colliculus

• Published in: The Journal of physiology Vol. 589; no. 16; pp. 3955 - 3967
• Main Authors: Geis, H.‐Rüdiger A. P., van der Heijden, Marcel, Borst, J. Gerard G.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2011; Wiley Subscription Services, Inc; Blackwell Science Inc
• Subjects: Action Potentials - physiology; Animals; Ears & hearing; Inferior Colliculi - cytology; Inferior Colliculi - physiology; Male; Membrane Potentials - physiology; Mice; Mice, Inbred C57BL; Neocortex - physiology; Neurons - physiology; Neuroscience; Owls
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.2011.210278

Non‐technical summary  Sensory information appears to be represented in a well‐organized manner in the central nervous system, but it is unclear whether this still holds true at the level of individual neurons. Here we found that the responses to sound of two neurons in the auditory midbrain that were lying right next to each other were not more similar than neurons that were far apart. Our results suggest a high local specialization of neuronal responses to sound stimulation in the dorsal cortex of the mouse inferior colliculus.   Simultaneous intracellular recordings of nearby neocortical neurons have demonstrated that their membrane potentials are highly correlated. The correlation between the spiking activity of nearby neocortical neurons may be much smaller, suggesting that inputs are more similar than outputs. Much less is known about the similarity of inputs in subcortical sensory areas. Here we investigate this question by making simultaneous whole‐cell recordings from neighbouring neurons in the dorsal cortex of the mouse inferior colliculus. No evidence for monosynaptic connections between neighbouring cells was observed, suggesting that integration of afferent signals plays a more important role than local processing. The correlation between frequency response areas of neighbouring cells varied but, surprisingly, neighbouring cells were on average not more similar in their responses to tones than non‐neighbouring neurons. This large micro‐heterogeneity suggests a sparse representation of acoustic features within the dorsal cortex.