Excitation of pyramidal tract cells by intracortical microstimulation: effective extent of stimulating current.

Stoney, Susan; Thompson, William E.; Asanuma, Hiroshi

doi:10.1152/jn.1968.31.5.659

Cited by 629 publications

(406 citation statements)

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“…We believe, however, that the electrical stimulation used in our studies activated a smaller span of direction columns than would a visual stimulus. From direct measurements made by Stoney et al (1968) in monkey motor cortex, we know that 10 A current pulses (the value used in the bulk of our experiments) activate neurons within ϳ85 m of the electrode tip. Because we selected microstimulation sites in which the preferred direction was approximately constant for 200 m of electrode travel, neurons activated by our stimulation currents should be substantially restricted to single direction columns.…”

Section: Discussionmentioning

confidence: 99%

Middle Temporal Visual Area Microstimulation Influences Veridical Judgments of Motion Direction

2002

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Microstimulation of direction columns in the middle temporal visual area (MT, or V5) provides a powerful tool for probing the relationship between cortical physiology and visual motion perception. In the current study we obtained "veridical" reports of perceived motion from rhesus monkeys by permitting a continuous range of possible responses that mapped isomorphically onto a continuous range of possible motion directions. In contrast to previous studies, therefore, the animals were freed from experimenter-imposed "categories" that typify forced choice tasks. We report three new findings: (1) MT neurons with widely disparate preferred directions can cooperate to shape direction estimates, inconsistent with a pure "winner-take-all" read-out algorithm and consistent with a distributed coding scheme like vector averaging, whereas neurons with nearly opposite preferred directions seem to compete in a manner consistent with the winner-take-all hypothesis, (2) microstimulation can influence direction estimates even when paired with the most powerful motion stimuli available, and (3) microstimulation effects can be elicited when a manual response (instead of our standard oculomotor response) is used to communicate the perceptual report.

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Section: Discussionmentioning

confidence: 99%

Middle Temporal Visual Area Microstimulation Influences Veridical Judgments of Motion Direction

2002

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“…We tested for PSP responses from each of the stimulating electrodes for all impaled neurons that had a stable membrane potential of at least Ϫ35 mV. Based on previous studies (Stoney et al, 1968), we chose a maximum stimulus of 60 A to minimize current spread and exclude the possibility of activating axons rostral or caudal of the lesion zone. Stimulus thresholds to evoke PSPs ranged from 10 to 60 A.…”

Section: Electrophysiologymentioning

confidence: 99%

“…However, unlike the antidromic experiments, the stimulating electrodes (rather than the recording electrodes) were assigned to one of these zones. As a consequence, the transition zones were lengthened by 250 m. This change was designed to take into account the current spread from stimulating electrodes (Stoney et al, 1968). The distance that current spreads from stimulating electrodes is much larger than the spread of extracellularly recorded antidromic action potentials (compare Fig.…”

Section: Stimulation Of Pci Axons Evokes Psps In Motoneuronsmentioning

confidence: 99%

Spinal Interneuron Axons Spontaneously Regenerate after Spinal Cord Injury in the Adult Feline

Fenrich¹,

Rose²

2009

J. Neurosci.

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It is well established that long, descending axons of the adult mammalian spinal cord do not regenerate after a spinal cord injury (SCI). These axons do not regenerate because they do not mount an adequate regenerative response and growth is inhibited at the injury site by growth cone collapsing molecules, such as chondroitin sulfate proteoglycans (CSPGs). However, whether axons of axotomized spinal interneurons regenerate through the inhibitory environment of an SCI site remains unknown. Here, we show that cut axons from adult mammalian spinal interneurons can regenerate through an SCI site and form new synaptic connections in vivo. Using morphological and immunohistochemical analyses, we found that after a midsagittal transection of the adult feline spinal cord, axons of propriospinal commissural interneurons can grow across the lesion despite a close proximity of their growth cones to CSPGs. Furthermore, using immunohistochemical and electrophysiological analyses, we found that the regenerated axons conduct action potentials and form functional synaptic connections with motoneurons, thus providing new circuits that cross the transected commissures. Our results show that interneurons of the adult mammalian spinal cord are capable of spontaneous regeneration after injury and suggest that elucidating the mechanisms that allow these axons to regenerate may lead to useful new therapeutic strategies for restoring function after injury to the adult CNS.

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“…Direct synaptic projections are supposed to activate neurons within a range of 125-600 m (Stoney et al, 1968;Tehovnik, 1996). Thus, the increase of glutamate in the EZ might be directly attributable to synaptic activation via stimulated nerve fibers originating from the SZ or indirectly attributable to missing inhibition from the SZ indicated by the decrease of parvalbumin in the fast-spiking basket cells and chandelier cells.…”

Section: Excitation Zonementioning

confidence: 99%

Excitation and Inhibition Jointly Regulate Cortical Reorganization in Adult Rats

Benali¹,

Weiler²,

Benali³

et al. 2008

J. Neurosci.

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The primary somatosensory cortex (SI) retains its capability for cortical reorganization after injury or differential use into adulthood. The plastic response of SI cells to peripheral stimulation is characterized by extension of cortical representations accompanied by changes of the receptive field size of neurons. We used intracortical microstimulation that is known to enforce local, intracortical synchronous activity, to induce cortical reorganization and applied immunohistochemical methods in the same individual animals to investigate how plasticity in the cortical topographic maps is linked to changes in the spatial layout of the inhibitory and excitatory neurotransmitter systems. The results reveal a differential spatiotemporal pattern of upregulation and downregulation of specific factors for an excitatory (glutamatergic) and an inhibitory (GABAergic) system, associated with changes of receptive field size and reorganization of the somatotopic map in the rat SI. Predominantly local mechanisms are the specific reduction of the calcium-binding protein parvalbumin in inhibitory neurons and the low expression of the activity marker c-Fos. Reorganization in the hindpaw representation and in the adjacent SI cortical areas (motor cortex and parietal cortex) is accompanied by a major increase of the excitatory transmitter glutamate and c-Fos. The spatial extent of the reorganization appears to be limited by an increase of glutamic acid decarboxylase and the inhibitory transmitter GABA. The local and medium-range net effects are excitatory and can facilitate receptive field enlargements and cortical map expansion. The longer-range increase of inhibition appears suited to limit these effects and to prevent neurons from pathological hyperexcitability.

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Excitation of pyramidal tract cells by intracortical microstimulation: effective extent of stimulating current.

Cited by 629 publications

References 0 publications

Middle Temporal Visual Area Microstimulation Influences Veridical Judgments of Motion Direction

Middle Temporal Visual Area Microstimulation Influences Veridical Judgments of Motion Direction

Spinal Interneuron Axons Spontaneously Regenerate after Spinal Cord Injury in the Adult Feline

Excitation and Inhibition Jointly Regulate Cortical Reorganization in Adult Rats

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