Functional changes in cat somatic sensory-motor cortex during short-term reversible epidural blocks

Metzler, Jacqueline; Marks, Philip S.

doi:10.1016/0006-8993(79)90790-x

Cited by 127 publications

(31 citation statements)

References 12 publications

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“…Thus many studies have found differences in perceptive fields, the appearance of discontinuous fields and increased convergence Kalahan et al 1981;Metzler & Marks, 1979;Dostrovsky & Millar, 1977;Franck, 1980). While 'flick' units and increased habituation were not found here, the longer latencies and lower following frequencies, without alteration in threshold, would suggest activation of a similar population of afferents but a poorer synaptic function.…”

mentioning

confidence: 47%

Rearrangement of neuronal responses in the trigeminal system of the rat following peripheral nerve section.

Waite¹

1984

The Journal of Physiology

118

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SUMMARY1. The infraorbital nerve was cut in either neonatal (on day 0) or adult (day 60) rats and the peripheral regeneration prevented. After 60 days either anatomical or electrophysiological techniques were used to study the peripheral nerve, trigeminal nucleus and somatosensory cortex.2. In neonatally sectioned animals the number of myelinated fibres surviving, at 60 days, in the peripheral nerve proximal to the lesion was 11 % compared with 100 % survival after adult nerve section.3. This reduction in surviving nerve fibres in neonatally lesioned animals was associated with a significant reduction in cross-sectional area of all trigeminal nuclei (principalis, oralis, interpolaris and caudalis) of 18-29 %. No significant change in area was present in animals sectioned as adults.4. Neonatally lesioned animals also showed a reduction of approximately 20% in the number of cells visible in cross-sections of all trigeminal nuclei.5. Animals sectioned as neonates showed marked plasticity at all nuclei in the trigeminal complex as well as in the cortex. Deafferented cells responded to new peripheral receptive fields so that the somatotopic organization of these cells was modified. Such cells are referred to throughout as 'reactivated' cells. However, in animals sectioned as adults no evidence of plasticity could be detected in the trigeminal nuclei. Only very limited reactivation was apparent in the cortex, so that the majority of deafferented cells remained unresponsive at both sites. 6. A detailed comparison was made of twenty-three reactivated cells and twentyfive normal cells from nucleus principalis of animals with nerve section on day 0. The reactivated cells commonly showed larger, more complex receptive fields, longer latencies and lower following frequencies, although stimulus thresholds were similar. Thus reactivated cells showed more convergence and poorer synaptic security than normal cells. However, stimulation of the contralateral thalamus produced similar responses from both groups of cells, suggesting that not all inputs to reactivated cells were modified.7. The time course of the reactivation of cells in nucleus caudalis from animals lesioned on day 0 was followed over 30 days. No acute effect, for up to 24 h, was detected. However, somatotopic reorganization had started by day 7, proceeded rapidly between days 7 and 14, and was completed by day 21.

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confidence: 47%

Rearrangement of neuronal responses in the trigeminal system of the rat following peripheral nerve section.

Waite¹

1984

The Journal of Physiology

118

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“…Rapid changes similar to these cortical changes have been observed in the adult rat spinal cord after injury of hindlimb nerves (Devor and Wall, 198 1 a;Markus et al, 1984;Wall and Devor, 1981), and at cortical and subcortical levels in other adult mammals (Dostrovsky et al, 1976;Jacquin et al, 1984;Kelahan and Doetsch, 1984;Metzler and Marks, 1979;Millar et al, 1976;Rasmusson and Tumbull, 1983), including primates (Merzenich and Kaas, 1982;Merzenith et al, 1983b), after a variety of peripheral injuries and manipulations. There is considerable evidence that normal cutaneous receptive fields do not fully reflect the wider range of inputs available to central somatosensory neurons (Chapin and Woodward, 198 1;Devor and Wall, 198 1 b;Devor et al, 1977;Dostrovsky et al, 1977;Jacquin et al, 1984;Macgillis et al, 1983;Mendell et al, 1978;Merrill and Wall, 1972;Mountcastle, 1957;Wall and Werman, 1976).…”

Section: Present Jindingsmentioning

confidence: 75%

The representation of peripheral nerve inputs in the S-I hindpaw cortex of rats raised with incompletely innervated hindpaws

Wall¹,

Cusick²

1986

J. Neurosci.

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The hindpaws of l-d-old rats were partially denervated by transection and ligation of the sciatic nerve. Following growth to adulthood, the topographical organization of the hindpaw representation in primary somatosensory (S-I) cortex was studied with neurophysiological mapping techniques and compared to the organization of previously studied normal adult rats and adult rats that had sciatic transection. The goals were (1) to determine how the topographical organization of the hindpaw representation is affected when development occurs with an incomplete set of peripheral inputs, and (2) to identify possible differences in the capacity of neonatal and adult CNSs to adjust to loss of inputs.The rat hindpaw is relatively immature on the day of birth. Neonatal transection and ligation of the sciatic nerve stunted gross development of the hindpaw and resulted in a permanent loss of low-threshold mechanoreceptor inputs from hindpaw zones normally innervated by the sciatic nerve.A comparison of the cortical representations of neonatally denervated and normal rats indicated that early loss of sciatic inputs caused several changes in the topographical organization of the hindpaw cortex, including (1) a loss of the representation of hindpaw skin areas innervated by the sciatic nerve, (2) a limited infringement of cutaneous inputs from the hindquarter into the cortical zone deprived of sciatic hindpaw inputs, (3) increased variability in the topographical relationships of the hindpaw and hindquarter representations, and (4) a decrease in the size of the cortical area responsive to cutaneous inputs.A comparison of the cortical representations of neonatal and adult denervates indicated that the general cortical reaction to sciatic injury at both ages was similar: Neurons in some parts of the deprived hindpaw cortex were activated by cutaneous inputs from uninjured nerves, whereas neurons in other parts of this cortex were unresponsive to cutaneous stimulation. The topographical organization and size of projection zones of uninjured peripheral inputs were different, however, after denervation in neonatal and adult rats.From these findings we suggest that (1) development of a normal, topographically organized hindpaw representation requires integration of hindpaw inputs in a spatially specific manner, (2) more than one pattern of cortical adjustment occurs after sciatic injury, and age is an important determinant of the pattern that is established, and (3) different mechanisms of central adjustment underlie age-related differences in cortical pat-

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“…At the level of the cortex, Metzler & Marks (1979) found that reversibly blocking the L4 and L5 dorsal roots resulted in receptive field shifts for about 30% of the units they tested.…”

Section: Relation To Other Studiesmentioning

confidence: 95%

“…Wall & Egger, 1971;Millar, Basbaum & Wall, 1976;Dostrovsky, Millar & Wall, 1976;Devor & Wall, 1981 a, b), have demonstrated that either acute or chronic deafferentation profoundly alters the receptive fields of individual somatosensory neurones, as well as the topographic organization of the somatosensory cortex, ventrobasal thalamus and dorsal column nuclei. Comparison of results obtained following acute (or reversible) and chronic denervation has indicated that substantial receptive field changes are more often observed at long intervals (>7 days) following deafferentation (see also Nakahama, Nishioka & Otsuka, 1966;Waite & Taylor, 1978;Metzler & Marks, 1979).…”

Section: Introductionmentioning

confidence: 99%

Altered somatosensory receptive fields in hamster colliculus after infraorbital nerve section and xylocaine injection.

Jacquin¹,

Mooney²,

Rhoades³

1984

The Journal of Physiology

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SUMMARY1. The effects of acute infraorbital (i.o.) nerve section upon the responses of somatosensory cells in the rostral part of the deep layers of the hamster's superior colliculus were studied using standard extracellular single-unit recording and receptive field mapping techniques.2. In nine animals a given cell's receptive field was determined both before and after i.o. nerve section and, in all cases, new areas of sensitivity were unmasked within 15 min after the nerve was cut.3. In a given electrode penetration where the i.o. nerve was sectioned (n = 13), somatosensory cells recorded after the nerve was cut, as the electrode was being withdrawn from the colliculus, exhibited receptive fields considerably different from those of somatosensory cells isolated during the descent of the recording electrode.4. Seventeen deep-layer somatosensory cells (in eight hamsters) were tested before and after subcutaneous injections of xylocaine into their receptive fields. This manipulation unmasked new areas of cutaneous sensitivity for sixteen units. Of these, the new receptive fields ofnine cells disappeared as sensitivity in the original receptive field returned; five ultimately retained both the new and old receptive fields; in two instances, sensitivity in the original receptive field never returned over the 3 h of testing.5. Control experiments (n = 7) demonstrated that the changes observed did not result from spontaneous alterations in receptive field borders, changes induced by variations in the level of general anaesthesia, or non-specific trauma associated with the xylocaine injections or the surgery required to expose the i.o. nerve.

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Functional changes in cat somatic sensory-motor cortex during short-term reversible epidural blocks

Cited by 127 publications

References 12 publications

Rearrangement of neuronal responses in the trigeminal system of the rat following peripheral nerve section.

Rearrangement of neuronal responses in the trigeminal system of the rat following peripheral nerve section.

The representation of peripheral nerve inputs in the S-I hindpaw cortex of rats raised with incompletely innervated hindpaws

Altered somatosensory receptive fields in hamster colliculus after infraorbital nerve section and xylocaine injection.

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