scholarly journals Trans-segmental imaging in the spinal cord of behaving mice

2021 ◽  
Author(s):  
Pavel Shekhtmeyster ◽  
Daniela Duarte ◽  
Erin M. Carey ◽  
Alexander Ngo ◽  
Grace Gao ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Activity Patterns ◽  
Field Of View ◽  
Lateral Resolution ◽  
Mechanical Stimuli ◽  
Spinal Segments ◽  
Working Distance

Spinal cord circuits play crucial roles in transmitting and gating cutaneous somatosensory modalities, such as pain, but the underlying activity patterns within and across spinal segments in behaving mice have remained elusive. To enable such measurements, we developed a wearable widefield macroscope with a 7.9 mm2 field of view, subcellular lateral resolution, 2.7 mm working distance, and <10 g overall weight. We show that highly localized painful mechanical stimuli evoke widespread, coordinated astrocyte excitation across multiple spinal segments.

scholarly journals Multiplex, translaminar imaging in the spinal cord of behaving mice

2021 ◽  
Author(s):  
Pavel Shekhtmeyster ◽  
Erin M. Carey ◽  
Daniela Duarte ◽  
Alexander Ngo ◽  
Grace Gao ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Imaging Techniques ◽  
Activity Patterns ◽  
Cell Types ◽  
Integrated System ◽  
Sensorimotor Processing ◽  
Activity Measurements ◽  
Multiple Challenges ◽  
Evoked Activity ◽  
Working Distance

While the spinal cord is known to play critical roles in sensorimotor processing, including pain-related signaling, corresponding activity patterns in genetically defined cell types across spinal laminae have remained elusive. Calcium imaging has enabled cellular activity measurements in behaving rodents but is currently limited to superficial regions. Using chronically implanted microprisms, we imaged sensory and motor evoked activity in regions and at speeds inaccessible by other high-resolution imaging techniques. To enable translaminar imaging in freely behaving animals through implanted microprisms, we additionally developed wearable microscopes with custom-compound microlenses. This new integrated system addresses multiple challenges of previous wearable microscopes, including their limited working distance, resolution, contrast, and achromatic range. The combination of these innovations allowed us to uncover that dorsal horn astrocytes in behaving mice show somatosensory program-dependent and lamina-specific calcium excitation. Additionally, we show that tachykinin precursor 1 (Tac1)-expressing neurons exhibit upper laminae-restricted activity to acute mechanical pain but not locomotion.

scholarly journals Commissural Interneurons in Rhythm Generation and Intersegmental Coupling in the Lamprey Spinal Cord

1999 ◽  
Vol 81 (5) ◽  
pp. 2037-2045 ◽  
Author(s):  
James T. Buchanan
Keyword(s):  
Spinal Cord ◽  
Amino Acid ◽  
Excitatory Amino Acid ◽  
Rhythmic Activity ◽  
Ventral Root ◽  
Rhythm Generation ◽  
Spinal Segment ◽  
Spinal Segments ◽  
Autocorrelation Method

Commissural interneurons in rhythm generation and intersegmental coupling in the lamprey spinal cord. To test the necessity of spinal commissural interneurons in the generation of the swim rhythm in lamprey, longitudinal midline cuts of the isolated spinal cord preparation were made. Fictive swimming was then induced by bath perfusion with an excitatory amino acid while recording ventral root activity. When the spinal cord preparation was cut completely along the midline into two lateral hemicords, the rhythmic activity of fictive swimming was lost, usually replaced with continuous ventral root spiking. The loss of the fictive swim rhythm was not due to nonspecific damage produced by the cut because rhythmic activity was present in split regions of spinal cord when the split region was still attached to intact cord. The quality of this persistent rhythmic activity, quantified with an autocorrelation method, declined with the distance of the split spinal segment from the remaining intact spinal cord. The deterioration of the rhythm was characterized by a lengthening of burst durations and a shortening of the interburst silent phases. This pattern of deterioration suggests a loss of rhythmic inhibitory inputs. The same pattern of rhythm deterioration was seen in preparations with the rostral end of the spinal cord cut compared with those with the caudal end cut. The results of this study indicate that commissural interneurons are necessary for the generation of the swimming rhythm in the lamprey spinal cord, and the characteristic loss of the silent interburst phases of the swimming rhythm is consistent with a loss of inhibitory commissural interneurons. The results also suggest that both descending and ascending commissural interneurons are important in the generation of the swimming rhythm. The swim rhythm that persists in the split cord while still attached to an intact portion of spinal cord is thus imposed by interneurons projecting from the intact region of cord into the split region. These projections are functionally short because rhythmic activity was lost within approximately five spinal segments from the intact region of spinal cord.

THE MOTILITY AND REACTIVITY OF THE OESTROGENIZED RABBIT UTERUS IN VIVO; WITH COMPARATIVE OBSERVATIONS ON MILK EJECTION

1958 ◽  
Vol 16 (3) ◽  
pp. 237-260 ◽  
Author(s):  
B. A. CROSS
Keyword(s):  
Spinal Cord ◽  
Mammary Gland ◽  
Spinal Anaesthesia ◽  
Dose Range ◽  
Abdominal Muscles ◽  
Mechanical Stimuli ◽  
Milk Ejection ◽  
Thoracic Spinal ◽  
Spontaneous Motility ◽  
Stimulation Of

SUMMARY The spontaneous motility of the intact uterus of spayed oestrogenized rabbits under sodium pentobarbitone anaesthesia has been recorded. Both uteri of each animal behaved similarly, and contractions often appeared to be synchronous. Small changes of load affected the amplitude of contractions, but did not alter uterine responsiveness to neurohypophysial or adrenomedullary hormones. Mid-thoracic section of the spinal cord obliterated spontaneous motility of the uterus; spinal anaesthesia did not. Spontaneous motility persisted for as long as 7 hr after decerebration and removal of the pituitary gland. The threshold dose of oxytocin for activating the oestrogenized uterus was the same as that for the lactating mammary gland, i.e. 1–5 mu. Doses up to 50 mu. usually gave an increase in frequency and amplitude of contractions. In the same dose range vasopressin either had little effect or inhibited spontaneous uterine motility, although milk ejection was stimulated. Slow infusion of oxytocin at rates of 1·5–48 mu./min produced graded increases in the rate and depth of uterine contractions and, at the same time, in similarly treated, lactating animals, rhythmic milk-ejection responses which at the higher rates of infusion merged to give a tetanic (plateau) type of milk ejection. Adrenaline or noradrenaline in doses of 1–5 μg produced diphasic uterine responses, initial contractions being followed by inhibition of spontaneous motility. They also inhibited the uterine, as well as the milk-ejection response to oxytocin injected 10–30 sec later. The inhibitory effect of adrenaline on both organs was about twice that of noradrenaline. The above-mentioned responses to adrenaline and oxytocin could also be elicited by electrical stimulation of the hypothalamus. Stimuli in the dorsal, lateral, perifornical and posterior hypothalamic areas produced effects equivalent to those of 1–5 μg adrenaline on both the uterus and mammary gland. These responses were abolished by mid-thoracic section of the spinal cord or by spinal anaesthesia. In such preparations responses typical of those produced by oxytocin were seen in both organs after stimulation of the paraventricular nuclei, supraoptic nuclei and the hypothalamo-hypophysial nerve pathways of the tuber cinereum and neural stalk. Dilatation of the vagina (or rectum) gave rise to a uterine response similar to that resulting from adrenaline or noradrenaline. The response was abolished by spinal anaesthesia, but not by mid-thoracic spinal section or decerebration. The same stimuli also produced 'bearing down' contractions of the abdominal muscles. Contractions of the uterus could also be elicited by mechanical stimuli, in the absence of functional spinal connexions.

Spinal stimulation to locate preganglionic neurons controlling the kidney, spleen, or intestine

1992 ◽  
Vol 263 (4) ◽  
pp. H1026-H1033 ◽  
Author(s):  
R. B. Taylor ◽  
L. C. Weaver
Keyword(s):  
Spinal Cord ◽  
Sympathetic Outflow ◽  
Renal Nerve ◽  
Homocysteic Acid ◽  
Sympathetic Control ◽  
The Third ◽  
Preganglionic Neurons ◽  
Spinal Segments ◽  
Vascular Beds ◽  
Nerve Discharge

The organization of sympathetic preganglionic neurons may be a substrate for selective control of sympathetic outflow to different vascular beds. This study was done to determine the spinal segments containing preganglionic neurons controlling discharge of renal, splenic, and mesenteric postganglionic nerves. In urethan-anesthetized rats, preganglionic neurons were stimulated by microinjecting D,L-homocysteic acid (3 nl, 0.17 M) into the lateral gray matter of the third thoracic (T3) to the fourth lumbar (L4) spinal segments. Responses from all three nerves could be elicited from segments T4-T13. The greatest increases in renal nerve discharge were evoked from segments T8-T12, the largest increase of 59 +/- 9% elicited from T10. Increases in splenic and mesenteric nerve discharge were smaller and were evoked more uniformly from T4-L3. The largest increases in discharge of splenic and mesenteric nerves were 19 +/- 5% (from T5) and 26 +/- 4% (from T10), respectively. The widely overlapping spinal cord segments controlling these three organs suggest that location of the preganglionic neurons in different spinal segments is not part of the mechanism for selective sympathetic control. However, the larger renal nerve responses demonstrate that sympathetic output to these organs can be differentiated at the level of the spinal cord.

Experimental Spinal Cord Injury: Spatiotemporal Characterization of Elemental Concentrations and Water Contents in Axons and Neuroglia

1999 ◽  
Vol 82 (5) ◽  
pp. 2143-2153 ◽  
Author(s):  
Richard M. LoPachin ◽  
Christopher L. Gaughan ◽  
Ellen J. Lehning ◽  
Yoshiro Kaneko ◽  
Thomas M. Kelly ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Water Content ◽  
Severely Injured ◽  
Channel Blockade ◽  
Compression Injury ◽  
Ion Distribution ◽  
Elemental Concentrations ◽  
Cord Injury ◽  
Spinal Segments

To examine the role of axonal ion deregulation in acute spinal cord injury (SCI), white matter strips from guinea pig spinal cord were incubated in vitro and were subjected to graded focal compression injury. At several postinjury times, spinal segments were removed from incubation and rapidly frozen. X-ray microanalysis was used to measure percent water and dry weight elemental concentrations (mmol/kg) of Na, P, Cl, K, Ca, and Mg in selected morphological compartments of myelinated axons and neuroglia from spinal cord cryosections. As an index of axon function, compound action potentials (CAP) were measured before compression and at several times thereafter. Axons and mitochondria in epicenter of severely compressed spinal segments exhibited early (5 min) increases in mean Na and decreases in K and Mg concentrations. These elemental changes were correlated to a significant reduction in CAP amplitude. At later postcompression times (15 and 60 min), elemental changes progressed and were accompanied by alterations in compartmental water content and increases in mean Ca. Swollen axons were evident at all postinjury times and were characterized by marked element and water deregulation. Neuroglia and myelin in severely injured epicenter also exhibited significant disruptions. In shoulder areas (adjacent to epicenter) of severely injured spinal strips, axons and mitochondria exhibited modest increases in mean Na in conjunction with decreases in K, Mg, and water content. Following moderate compression injury to spinal strips, epicenter axons exhibited early (10 min postinjury) element and water deregulation that eventually recovered to near control values (60 min postinjury). Na+ channel blockade by tetrodotoxin (TTX, 1 μM) perfusion initiated 5 min after severe crush diminished both K loss and the accumulation of Na, Cl, and Ca in epicenter axons and neuroglia, whereas in shoulder regions TTX perfusion completely prevented subcellular elemental deregulation. TTX perfusion also reduced Na entry in swollen axons but did not affect K loss or Ca gain. Thus graded compression injury of spinal cord produced subcellular elemental deregulation in axons and neuroglia that correlated with the onset of impaired electrophysiological function and neuropathological alterations. This suggests that the mechanism of acute SCI-induced structural and functional deficits are mediated by disruption of subcellular ion distribution. The ability of TTX to reduce elemental deregulation in compression-injured axons and neuroglia implicates a significant pathophysiological role for Na+ influx in SCI and suggests Na+ channel blockade as a pharmacotherapeutic strategy.

Development of specific muscle and cutaneous sensory projections in cultured segments of spinal cord

Development ◽  
1994 ◽  
Vol 120 (5) ◽  
pp. 1315-1323 ◽  
Author(s):  
K. Sharma ◽  
Z. Korade ◽  
E. Frank
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Muscle Afferents ◽  
Cutaneous Afferents ◽  
In Ovo ◽  
Sensory Afferents ◽  
Chicken Embryos ◽  
Sensory Projections ◽  
Spinal Segments ◽  
Horn Development

Development of sensory projections was studied in cultured spinal segments with attached dorsal root ganglia. In spinal segments from stage 30 (E6.5) and older chicken embryos, prelabeled muscle and cutaneous afferents established appropriate projections. Cutaneous afferents terminated solely within the dorsolateral laminae, whereas some muscle afferents (presumably Ia afferents) projected ventrally towards motoneurons. Development of appropriate projections suggests that sufficient cues are preserved in spinal segments to support the formation of modality-specific sensory projections. Further, because these projections developed in the absence of muscle or skin, these results show that the continued presence of peripheral targets is not required for the formation of specific central projections after stage 29 (E6.0). Development of the dorsal horn in cultured spinal segments was assessed using the dorsal midline as a marker. In ovo, this midline structure appears at stage 29. Lack of midline formation in stage 28 and 29 cultured spinal segments suggests that the development of the dorsal horn is arrested in this preparation. This is consistent with earlier reports suggesting that dorsal horn development may be dependent on factors outside the spinal cord. Because dorsal horn development is blocked in cultured spinal segments, this preparation makes it possible to study the consequences of premature ingrowth of sensory axons into the spinal cord. In chicken embryos sensory afferents reach the spinal cord at stage 25 (E4.5) but do not arborize within the gray matter until stage 30. During this period dorsal horn cells are still being generated. In spinal segments, only those segments that have developed a midline at the time of culture support the formation of midline at the time of culture support the formation of specific sensory projections.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional Specificity of Spinal Cord Segments in the Control of Limb Movements

Development ◽  
1963 ◽  
Vol 11 (2) ◽  
pp. 431-444
Author(s):  
George Székely
Keyword(s):  
Spinal Cord ◽  
Limb Movement ◽  
Limb Movements ◽  
Functional Specificity ◽  
Ample Evidence ◽  
Embryonic Life ◽  
Spinal Segments ◽  
Supernumerary Limbs ◽  
Experimental Approaches ◽  
Central Apparatus

There is ample evidence that limbs innervated by spinal segments which normally do not supply limbs, do not exhibit co-ordinated movements (Detwiler, 1920). Nerve formation under such circumstances seems to be fairly normal, i.e. essentially characteristic for the innervated limb (Detwiler, 1920; Piatt, 1956), so that failure of nerve formation and of re-innervation of the muscles cannot be blamed for the result. It is more probable that the limbinnervating segments of the spinal cord: the brachial (segments 3, 4, 5 in the newt) and the lumbo-sacral (segments 16, 17, 18) might alone possess a central apparatus determined in early embryonic life with the capacity to innervate and move limbs in a co-ordinated manner (Detwiler, 1936; Weiss, 1955; Rogers, 1934). Although some experimental approaches (Moyer, 1943, Piatt, 1957) were unsuccessful, it is obvious that this problem could best be investigated by transplanting brachial or lumbo-sacral segments into the place of the thoracic segments, and by additionally implanting at the same level supernumerary limbs to be innervated by the grafted cord segments that might contain the postulated specific apparatus for co-ordinated limb movement.

Intrinsic Properties Shape the Firing Pattern of Ventral Horn Interneurons From the Spinal Cord of the Adult Turtle

2006 ◽  
Vol 96 (5) ◽  
pp. 2670-2677 ◽  
Author(s):  
Morten Smith ◽  
Jean-François Perrier
Keyword(s):  
Spinal Cord ◽  
Activity Patterns ◽  
Ventral Horn ◽  
Inward Rectification ◽  
Intrinsic Properties ◽  
Patch Clamp Technique ◽  
Firing Patterns ◽  
Pharmacological Tests ◽  
Low Threshold

Interneurons in the ventral horn of the spinal cord play a central role in motor control. In adult vertebrates, their intrinsic properties are poorly described because of the lack of in vitro preparations from the spinal cord of mature mammals. Taking advantage of the high resistance to anoxia in the adult turtle, we used a slice preparation from the spinal cord. We used the whole cell blind patch-clamp technique to record from ventral horn interneurons. We characterized their firing patterns in response to depolarizing current pulses and found that all the interneurons fired repetitively. They displayed bursting, adapting, delayed, accelerating, or oscillating firing patterns. By combining electrophysiological and pharmacological tests, we showed that interneurons expressed slow inward rectification, plateau potential, voltage-sensitive transient outward rectification, and low-threshold spikes. These results demonstrate a diversity of intrinsic properties that may enable a rich repertoire of activity patterns in the network of ventral horn interneurons.

Spinal Cord Coordination of Hindlimb Movements in the Turtle: Intralimb Temporal Relationships During Scratching and Swimming

1997 ◽  
Vol 78 (3) ◽  
pp. 1394-1403 ◽  
Author(s):  
Edelle C. Field ◽  
Paul S. G. Stein
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Activity Patterns ◽  
Angular Position ◽  
Knee Extension ◽  
Neuron Activity ◽  
Spinal Circuitry ◽  
Temporal Relationships ◽  
Kinematic Analyses ◽  
Behavioral Event

Field, Edelle C. and Paul S. G. Stein. Spinal cord coordination of hindlimb movements in the turtle: intralimb temporal relationships during scratching and swimming. J. Neurophysiol. 78: 1394–1403, 1997. Spinal cord neuronal circuits generate motor neuron activity patterns responsible for rhythmic hindlimb behaviors such as scratching and swimming. Kinematic analyses of limb movements generated by this motor neuron output reveal important characteristics of these behaviors. Intralimb kinematics of the turtle hindlimb were characterized during five distinct rhythmic forms of behavior: three forms of scratching and two forms of swimming. In each movement cycle for each form, the angles of the hip and knee joints were measured as well as the timing of a behavioral event, e.g., rub onset in scratching or powerstroke onset in swimming. There were distinct differences between the kinematics of different forms of the same behavior, e.g., rostral scratch versus pocket scratch. In contrast, there were striking similarities between forms of different behaviors, e.g., rostral scratch versus forward swimming. For each form of behavior there was a characteristic angular position of the hip at the onset of each behavioral event (rub or powerstroke). The phase of the onset of knee extension within the hip position cycle occurred while the hip was flexing in the rostral scratch and forward swim and while the hip was extending in the pocket scratch, caudal scratch, and back-paddling form of swimming. The phase of the onset of the behavioral event was not statistically different between rostral scratch and forward swim; nor was it different between pocket scratch and caudal scratch. These observations of similarities at the movement level support the suggestion that further similarities, such as shared spinal circuitry, may be present at the neural circuitry level as well.

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