Increased receptive field size of dorsal horn neurons following chronic spinal cord hemisections in cats

Brenowitz, Gene L.; Pubols, Lillian M.

doi:10.1016/0006-8993(81)91277-4

Cited by 34 publications

(10 citation statements)

References 40 publications

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“…neurones are located in laminae III, IV and V, areas of the dorsal horn that have been sampled frequently, but they are relatively difficult to record from with extracellular electrodes as they have small extracellular field potentials . Spatially separate components of cutaneous receptive fields of dorsal horn neurones have been reported (Devor & Wall, 1976;Pubols & Goldberger, 1980;Brenowitz & Pubols, 1981). It is also a fairly common observation that the high threshold component may extend beyond (around) a central low threshold area (Lundberg & Oscarsson, 1961;Hillman & Wall, 1969).…”

Section: Discussionmentioning

confidence: 94%

Receptive field organization and response properties of spinal neurones with axons ascending the dorsal columns in the cat.

Brown¹,

Brown²,

Fyffe³

et al. 1983

The Journal of Physiology

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SUMMARY1. Micro-electrode recordings were made from single post-synaptic axons in the dorsal columns of cats anaesthetized with chloralose and paralysed with gallamine triethiodide. The recordings were made from the L5 segment and the axons were shown to project to the upper cervical level.2. Forty-eight units were recorded and the axons had conduction velocities of 22-61 ms-1, averaging 38-3 ms-1.3. Excitatory receptive fields were complex in many units, being made up of clearly defined, separate, low and high threshold areas. The receptive fields were often discontinuous. Only a few units behaved as if they received excitatory input from a single class of mechanoreceptors. A minority (13 %) of units had labile, excitatory receptive fields that expanded in size during the recording period.4. About 40 % of the units had inhibitory receptive fields. These were of two main types: either small and within or adjacent to the excitatory field, or large and separated from or adjacent to the excitatory field. 5. The great majority of units had resting discharges upon isolation and these consisted of single impulses or bursts of impulses at short intervals separated by longer, irregular periods.6. The time course of inhibition produced by electrical stimulation of cutaneous nerves suggested presynaptic inhibitory components to the inhibition. Some inhibitory curves were very prolonged with maxima at about 100 ms and total durations of up to 400 ms.7. The complexity of the receptive field organization in these dorsal horn neurones is discussed, as is their possible significance as input neurones to the dorsal column nuclei.

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Section: Discussionmentioning

confidence: 94%

Receptive field organization and response properties of spinal neurones with axons ascending the dorsal columns in the cat.

Brown¹,

Brown²,

Fyffe³

et al. 1983

The Journal of Physiology

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“…Considering the disruption of descending pathways would be particularly important in the case of incomplete spinal lesions. In fact, loss of descending inhibition onto spared spinothalamic fibers can lead to hyperactivity of dorsal horn neurons originating from the spinothalamic tract, 32,33 and to supraspinal hyperexcitability in response to preserved spinothalamic inputs. 34 The equilibrium between dorsal column deafferentation and spinothalamic hyperactivity is thus likely to have a critical role in determining the anesthetic requirements after incomplete spinal cord injuries.…”

Section: Discussionmentioning

confidence: 99%

Spinal cord injury immediately decreases anesthetic requirements in rats

et al. 2011

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Study design: Pharmacologically blocking the spinal cord produces sedative effects and reduces anesthesia requirements in patients and animals. Whether spinal cord injury also reduces anesthesia requirements remains unclear. Methods: We retrospectively analyzed data from urethane-anesthetized rats 15 to assess anesthesia requirements immediately after complete thoracic transection of the spinal cord. The depth of anesthesia was monitored up to 12 h after spinal transection by the reflexes to noxious stimuli and by electrophysiological recordings from the infragranular layers of the primary somatosensory cortex. Whenever animals displayed electrophysiological and/or behavioral signs of activation, we delivered an additional dose of anesthesia. Anesthetic requirements in animals receiving spinal transection (n ¼ 11) were compared with control animals receiving 'sham' lesion (n ¼ 9). Results: The cumulative dose necessary to maintain a stable level of anesthesia was significantly lower in transected animals compared with control animals. By about 7 h after spinal cord injury, on average the cumulative dose of urethane was only 1.13 ± 0.14 of the original dose, compared with 1.64 ± 0.19 of the original dose in control animals. Conclusions: Spinal transection immediately decreased anesthetic requirements in rats. To establish whether these results are relevant for patients with spinal cord injury will require further investigation.

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“…The morphological correlates of the posthemisection expansion of receptive fields are collateral sprouting of dorsal roots 27 and activation of ineffective synapses as discussed previously.…”

Section: Responses To Hemisection Of the Spinal Cordmentioning

confidence: 74%

“…The dorsal roots on the side of hemisection show an enlargement of their receptive fields. 27 Many functional and structural mechanisms have been proposed to account for these behavioral changes induced by hemisection.…”

Section: Responses To Hemisection Of the Spinal Cordmentioning

confidence: 99%

Neural Plasticity

Bishop

1982

Physical Therapy

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Most patients treated by physical therapists have suffered some neurological trauma resulting from disease or injury. The traditional teaching used to be that damage of central neurons is irreversible. Within the last decade, however, it has been necessary to cast aside this traditional view because of accumulating evidence that the brain is endowed with remarkable plasticity. This paper reviews experimental evidence revealing morphological and functional changes occurring in the CNS in response to neural lesions. Morphological responses to injury include collateral and terminal sprouting, retrieval of vacated synapses, alterations in the ultrastructure of surviving synapses, and denervation supersensitivity. Functional and adaptive changes induced by injury include the unmasking of ineffective synapses, shifts in receptive fields, and reorganization or altered effectiveness of surviving neural networks. These recovery phenomena attest to the brain's dynamic properties. These new insights contradict our conventional view of the absence of growth and reorganizational capabilities in CNS neurons. These newly identified "recovery phenomena" are destined to have a significant impact on physical therapy in the future.

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Increased receptive field size of dorsal horn neurons following chronic spinal cord hemisections in cats

Cited by 34 publications

References 40 publications

Receptive field organization and response properties of spinal neurones with axons ascending the dorsal columns in the cat.

Receptive field organization and response properties of spinal neurones with axons ascending the dorsal columns in the cat.

Spinal cord injury immediately decreases anesthetic requirements in rats

Neural Plasticity

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