Effects of Glutamate andγ-Aminobutyric Acid on Spontaneously Active Intraocular Spinal Cord Graft Neurons

Pieces of fetal rat lumbar spinal cord were transplanted into the anterior eye chamber of adult rat hosts. At least seven months later, extracellular single-unit recordings of spontaneously active graft neurons were made prior to and during the superfusion of either glutamate orγ-aminobutyric acid (GABA). Superfusion of glutamate produced an increase (five cells), decrease (three cells), or had no effect (two cells) on the firing rate of neurons tested. Superfusion of GABA decreased the firing rate of all twelve neurons tested, while superfusion of the GABA receptor antagonist bicuculline increased the firing rates of all eight neurons tested. The latency and magnitude of the responses to glutamate and GABA were not related to depth of the recording electrode below the graft surface. Together, these data suggest that the intraocular spinal cord graft is suitable for thein vivostudy of GABA and glutamate neuropharmacology.

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Features of laminar and somatotopic organization of lumbar spinal cord units receiving cutaneous inputs from hindlimb receptive fields

Journal of Neurophysiology ◽

10.1152/jn.1984.52.3.449 ◽

1984 ◽

Vol 52 (3) ◽

pp. 449-458 ◽

Cited By ~ 40

Author(s):

A. R. Light ◽

R. G. Durkovic

Keyword(s):

Spinal Cord ◽

Receptive Field ◽

Receptive Fields ◽

Lumbar Spinal Cord ◽

Spinal Neurons ◽

Spinal Cord Neurons ◽

Somatotopic Organization ◽

Single Unit Recordings ◽

Lumbar Spinal ◽

Rectangular Columns

Single-unit recordings from 312 units of lamina I-VII of the lumbar spinal cord of unanesthetized, decerebrate, T8 spinal cats were used to determine the somatotopic and laminar organization of spinal neurons responding to cutaneous stimulation of the hindlimb. Properties of cells confined to different Rexed laminae (I-VII) were shown to differ in several respects, including responses to variations in stimulus intensity, receptive-field areas, spontaneous frequencies, and central delays. Spinal cord neurons with similarly localized cutaneous receptive fields were found to be organized in sagittally oriented rectangular columns. These columns were 7 to at least 20 mm long (rostral-caudal axis), 0.5-1.0 mm wide, and could encompass laminae I-VII in depth. Touch, pressure, and pinch were effective excitatory inputs into each column subserving a given receptive-field location. A map of the somatotopic organization of units in the horizontal plane is presented, which in general confirms previous reports and in particular deals with the organization of units with receptive fields on the plantar cushion and individual toes.

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Active Dendritic Integration of Inhibitory Synaptic Inputs In Vivo

Journal of Neurophysiology ◽

10.1152/jn.00521.2003 ◽

2003 ◽

Vol 90 (6) ◽

pp. 3617-3624 ◽

Cited By ~ 45

Author(s):

Jason J. Kuo ◽

Robert H. Lee ◽

Michael D. Johnson ◽

Heather M. Heckman ◽

C. J. Heckman

Keyword(s):

Spinal Cord ◽

Lumbar Spinal Cord ◽

Standard State ◽

Dendritic Integration ◽

Local Inhibition ◽

Highly Active ◽

Linear Integration ◽

Inward Currents ◽

Lumbar Spinal

Synaptic integration in vivo often involves activation of many afferent inputs whose firing patterns modulate over time. In spinal motoneurons, sustained excitatory inputs undergo enormous enhancement due to persistent inward currents (PICs) that are generated primarily in the dendrites and are dependent on monoaminergic neuromodulatory input from the brain stem to the spinal cord. We measured the interaction between dendritic PICs and inhibition generated by tonic electrical stimulation of nerves to antagonist muscles during voltage clamp in motoneurons in the lumbar spinal cord of the cat. Separate samples of cells were obtained for two different states of monoaminergic input: standard (provided by the decerebrate preparation, which has tonic activity in monoaminergic axons) and minimal (the chloralose anesthetized preparation, which lacks tonic monoaminergic input). In the standard state, steady inhibition that increased the input conductance of the motoneurons by an average of 38% reduced the PIC by 69%. The range of this reduction, from <10% to >100%, was proportional to the magnitude of the applied inhibition. Thus nearly linear integration of synaptic inhibition may occur in these highly active dendrites. In the minimal state, PICs were much smaller, being approximately equal to inhibition-suppressed PICs in the standard state. Inhibition did not further reduce these already small PICs. Overall, these results demonstrate that inhibition from local spinal circuits can oppose the facilitation of dendritic PICs by descending monoaminergic inputs. As a result, local inhibition may also suppress active dendritic integration of excitatory inputs.

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An in vivo method for recording single unit activity in lumbar spinal cord in mice anesthetized with a volatile anesthetic

Brain Research Protocols ◽

10.1016/j.brainresprot.2004.03.002 ◽

2004 ◽

Vol 13 (2) ◽

pp. 126-134 ◽

Cited By ~ 6

Author(s):

Jason M Cuellar ◽

Joseph F Antognini ◽

Earl Carstens

Keyword(s):

Spinal Cord ◽

Unit Activity ◽

Single Unit ◽

Volatile Anesthetic ◽

Lumbar Spinal Cord ◽

Single Unit Activity ◽

Lumbar Spinal

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Characterization of DTI Indices in the Cervical, Thoracic, and Lumbar Spinal Cord in Healthy Humans

Radiology Research and Practice ◽

10.1155/2012/143705 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

Rachael L. Bosma ◽

Patrick W. Stroman

Keyword(s):

Spinal Cord ◽

Mean Diffusivity ◽

Lumbar Spinal Cord ◽

Single Shot ◽

Tissue Properties ◽

Healthy Humans ◽

Diffusion Weighted Images ◽

Lumbar Spinal

The aim of this study was to characterizein vivomeasurements of diffusion along the length of the entire healthy spinal cord and to compare DTI indices, including fractional anisotropy (FA) and mean diffusivity (MD), between cord regions. The objective is to determine whether or not there are significant differences in DTI indices along the cord that must be considered for future applications of characterizing the effects of injury or disease. A cardiac gated, single-shot EPI sequence was used to acquire diffusion-weighted images of the cervical, thoracic, and lumbar regions of the spinal cord in nine neurologically intact subjects (19 to 22 years). For each cord section, FA versus MD values were plotted, and a k-means clustering method was applied to partition the data according to tissue properties. FA and MD values from both white matter (averageFA=0.69, averageMD=0.93×10−3 mm2/s) and grey matter (averageFA=0.44, averageMD=1.8×10−3 mm2/s) were relatively consistent along the length of the cord.

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Dorsal Horn of Mouse Lumbar Spinal Cord Imaged with CLARITY

BioMed Research International ◽

10.1155/2020/3689380 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Gulgun Sengul ◽

Huazheng Liang ◽

Teri M. Furlong ◽

George Paxinos

Keyword(s):

Spinal Cord ◽

Dorsal Horn ◽

Aminobutyric Acid ◽

Lumbar Spinal Cord ◽

Spinal Cord Tissue ◽

Gamma Aminobutyric Acid ◽

Immunohistochemical Markers ◽

Calcitonin Gene ◽

Clearing Technique ◽

Lumbar Spinal

The organization of the mouse spinal dorsal horn has been delineated in 2D for the six Rexed laminae in our publication Atlas of the Spinal Cord: Mouse, Rat, Rhesus, Marmoset, and Human. In the present study, the tissue clearing technique CLARITY was used to observe the cyto- and chemoarchitecture of the mouse spinal cord in 3D, using a variety of immunohistochemical markers. We confirm prior observations regarding the location of glycine and serotonin immunoreactivities. Novel observations include the demonstration of numerous calcitonin gene-related peptide (CGRP) perikarya, as well as CGRP fibers and terminals in all laminae of the dorsal horn. We also observed sparse choline acetyltransferase (ChAT) immunoreactivity in small perikarya and fibers and terminals in all dorsal horn laminae, while gamma aminobutyric acid (GABA) and glutamate decarboxylase-67 (GAD67) immunoreactivities were found only in small perikarya and fibers. Finally, numerous serotonergic fibers were observed in all laminae of the dorsal horn. In conclusion, CLARITY confirmed the 2D immunohistochemical properties of the spinal cord. Furthermore, we observed novel anatomical characteristics of the spinal cord and demonstrated that CLARITY can be used on spinal cord tissue to examine many proteins of interest.

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