scholarly journals Modularity in the Microcircuitry of the Mouse Inferior Colliculus Yields Dual Processing Streams for Auditory and Multisensory Information

2019 ◽  
Author(s):  
Alexandria M. H. Lesicko ◽  
Daniel A. Llano
Keyword(s):  
Inferior Colliculus ◽  
Brain Slices ◽  
Cell Types ◽  
Dorsal Column ◽  
Central Nucleus ◽  
Dual Processing ◽  
Dorsal Column Nuclei ◽  
Somatosensory Stimuli ◽  
Caged Glutamate ◽  
Multisensory Information

ABSTRACTThe lateral cortex of the inferior colliculus (LCIC) is parcellated into two neurochemical compartments: one that comprises periodic neurochemical modules rich in GABAergic and cholinergic terminals and an extramodular matrix rich in calretinin neurons. We recently found that projections from auditory structures (auditory cortex and central nucleus of the IC) target the extramodular matrix, while somatosensory structures (somatosensory cortex and dorsal column nuclei) target the modules. What is peculiar about this finding of segregated inputs is that previous work has found that many LCIC neurons respond to both auditory and somatosensory stimuli. To investigate how these pathways interact, here we use laser photostimulation of caged glutamate to interrogate local LCIC circuits in brain slices from mouse. We found that most cell types in the LCIC receive inputs only from their home domain, but that GABAergic neurons in the modules serve as a bridge between modules and extramodular space. Further, we found that residence in- or out-of a module strongly predicted the output connectivity of that cell. These data suggest that distinct processing streams are seen in the LCIC and that GABAergic cells in modules serve to link these streams.

Inferior colliculus. I. Comparison of response properties of neurons in central, pericentral, and external nuclei of adult cat

1975 ◽  
Vol 38 (5) ◽  
pp. 1196-1207 ◽  
Author(s):  
L. M. Aitkin ◽  
W. R. Webster ◽  
J. L. Veale ◽  
D. C. Crosby
Keyword(s):  
Inferior Colliculus ◽  
Physiological Responses ◽  
Cell Types ◽  
Central Nucleus ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Common ◽  
Adult Cat ◽  
Tonal Stimuli ◽  
Anesthetized Cat

The responses of 150 units in the central (ICC), pericentral (ICP), and external nuclei (ICX) of the inferior colliculus of the anesthetized cat were studied in relation to their tuning characteristics and binaural responses to tonal stimuli. Units in ICC were characterized by sharp tuning and binaural responses, while those in ICP and ICX were frequently very broadly tuned with a poorly defined best frequency. Nonetheless, in the latter nuclei a tendency existed for tonotopic organization to occur with high frequencies located externally and low frequencies at the margins of the central nucleus. Tuning measurements were hampered by the common occurrence of habituation in the discharges of single units in ICP and, to a lesser extend, ICX. The majority of units in ICP could be differentiated from those in ICX by their monaural input. Speculations were advanced linking anatomical cell types to physiological responses in the three nuclei and into the possible functional significance of the different behavior of units to tonal stimuli.

Projection from dorsal column nuclei to dorsal mesencephalon

1985 ◽  
Vol 53 (1) ◽  
pp. 183-200 ◽  
Author(s):  
L. L. Cooper ◽  
J. O. Dostrovsky
Keyword(s):  
Superior Colliculus ◽  
Inferior Colliculus ◽  
Receptive Fields ◽  
Dorsal Column ◽  
The Body ◽  
Projection Neurons ◽  
Dorsal Column Nuclei ◽  
Wide Range ◽  
Somatosensory Input ◽  
Medial Geniculate

This study investigated the projection from the dorsal column nuclei (DCN) to the dorsal mesencephalon. Single-unit extracellular recordings were obtained from the DCN of alpha-chloralose anesthetized cats. Neurons were identified by standard antidromic stimulation criteria as projecting to the dorsal mesencephalon (M neurons), the diencephalon (D neurons), or to both regions (MD neurons). Fifty-two neurons could be antidromically activated from the dorsal mesencephalon. Of these, 31 could also be antidromically activated by stimulation in the diencephalon. An additional 34 neurons were studied that could be antidromically activated only from the diencephalon. Stimulation sites within the dorsal mesencephalon effective in antidromically activating M and MD neurons were in the caudal ventrolateral superior colliculus, the intercollicular area, and external nucleus of the inferior colliculus. Effective diencephalic stimulation sites were in the ventroposterolateral nucleus, the zona incerta, and the magnocellular division of the medial geniculate. The antidromic latencies to stimulation in the dorsal mesencephalon of M and MD neurons spanned a similar but wide range of values in contrast to the latencies to stimulation in the diencephalon of D neurons which were all short. Conduction velocities along the mesencephalic and diencephalic collaterals of MD neurons were similar. Many of the neurons projecting to the mesencephalon had receptive fields located proximally on the body. Most of the neurons had rapidly adapting responses to low-intensity mechanical stimulation of the skin. The major difference between the mesencephalic M and MD projection neurons and diencephalic projection D neurons was the larger percentage of neurons having proximal receptive fields in the former group. These findings are the first electrophysiological demonstration of a direct somatosensory input to the dorsal mesencephalon arising in the DCN. This input is probably responsible for providing some of the somatosensory input to the deeper layers of the superior colliculus, the external nucleus of the inferior colliculus, and the intercollicular area, regions known to have neurons responding to somatosensory stimuli.

scholarly journals Novel neural signal features permit robust machine-learning of natural tactile- and proprioception-dominated dorsal column nuclei signals

2019 ◽  
Author(s):  
Alastair J Loutit ◽  
Jason R Potas
Keyword(s):  
Machine Learning ◽  
Time Course ◽  
Movement Control ◽  
Dorsal Column ◽  
Neural Decoding ◽  
Dorsal Column Nuclei ◽  
Neural Signals ◽  
Brain Signals ◽  
Signal Features ◽  
Somatosensory Stimuli

Neural prostheses enable users to effect movement through a variety of actuators by translating brain signals into movement control signals. However, to achieve more natural limb movements from these devices, restoration of somatosensory feedback and advances in neural decoding of motor control-related brain signals are required. We used a machine-learning approach to assess signal features for their capacity to enhance decoding performance of neural signals evoked by natural tactile and proprioceptive somatosensory stimuli, recorded from the surface of the dorsal column nuclei in urethane-anaesthetised rats. We determined signal features that are highly informative for decoding somatosensory stimuli, yet these appear underutilised in neuroprosthetic applications. We found that proprioception-dominated stimuli generalise across animals better than tactile-dominated stimuli, and we demonstrate how information that signal features contribute to neural decoding changes over a time-course of dynamic somatosensory events. These findings may improve neural decoding for various applications including novel neuroprosthetic design.

scholarly journals Identification of cell types in brain slices of the inferior colliculus

Neuroscience ◽  
2000 ◽  
Vol 101 (2) ◽  
pp. 403-416 ◽  
Author(s):  
D Peruzzi ◽  
S Sivaramakrishnan ◽  
D.L Oliver
Keyword(s):  
Inferior Colliculus ◽  
Brain Slices ◽  
Cell Types

Single-Unit Responses in the Inferior Colliculus of Decerebrate Cats II. Sensitivity to Interaural Level Differences

1999 ◽  
Vol 82 (1) ◽  
pp. 164-175 ◽  
Author(s):  
Kevin A. Davis ◽  
Ramnarayan Ramachandran ◽  
Bradford J. May
Keyword(s):  
Frequency Response ◽  
Inferior Colliculus ◽  
Free Field ◽  
Central Nucleus ◽  
Type I ◽  
Discharge Rates ◽  
Ipsilateral Stimulation ◽  
Interaural Level Differences ◽  
Type V ◽  
Decerebrate Cats

Single units in the central nucleus of the inferior colliculus (ICC) of unanesthetized decerebrate cats can be grouped into three distinct types (V, I, and O) according to the patterns of excitation and inhibition revealed in contralateral frequency response maps. This study extends the description of these response types by assessing their ipsilateral and binaural response map properties. Here the nature of ipsilateral inputs is evaluated directly using frequency response maps and compared with results obtained from methods that rely on sensitivity to interaural level differences (ILDs). In general, there is a one-to-one correspondence between observed ipsilateral input characteristics and those inferred from ILD manipulations. Type V units receive ipsilateral excitation and show binaural facilitation (EE properties); type I and type O units receive ipsilateral inhibition and show binaural excitatory/inhibitory (EI) interactions. Analyses of binaural frequency response maps show that these ILD effects extend over the entire receptive field of ICC units. Thus the range of frequencies that elicits excitation from type V units is expanded with increasing levels of ipsilateral stimulation, whereas the excitatory bandwidth of type I and O units decreases under the same binaural conditions. For the majority of ICC units, application of bicuculline, an antagonist for GABAA-mediated inhibition, does not alter the basic effects of binaural stimulation; rather, it primarily increases spontaneous and maximum discharge rates. These results support our previous interpretations of the putative dominant inputs to ICC response types and have important implications for midbrain processing of competing free-field sounds that reach the listener with different directional signatures.

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