Brain Activation Sequences Following Electrical Limb Stimulation of Normal and Paraplegic Subjects

Ioannides, Andreas A.; Liu, Lichan; Khurshudyan, Ara; Bodley, R; Poghosyan, Vahe; Shibata, Tadahiko; Dammers, Jürgen; Jamous, Ali

doi:10.1006/nimg.2002.1065

Cited by 18 publications

(13 citation statements)

References 36 publications

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“…Ionnides et al found normal SII activation in 3͞3 paraplegics but only weak SI foot activation in one subject (35). The data herein extend those studies by assessing preservation and rearrangement of cortical topography (face vs. hand vs. foot) in the rare case of partial recovery years after SCI.…”

Section: Resultssupporting

confidence: 75%

Functional reorganization and stability of somatosensory-motor cortical topography in a tetraplegic subject with late recovery

Corbetta

Burton

Sinclair

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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The functional organization of somatosensory and motor cortex was investigated in an individual with a high cervical spinal cord injury, a 5-year absence of nearly all sensory͞motor function at and below the shoulders, and rare recovery of some function in years 6 -8 after intense and sustained rehabilitation therapies. We used functional magnetic resonance imaging to study brain activity to vibratory stimulation and voluntary movements of body parts above and below the lesion. No response to vibratory stimulation of the hand was observed in the primary somatosensory cortex (SI) hand area, which was conversely recruited during tongue movements that normally evoke responses only in the more lateral face area. This result suggests SI reorganization analogous to previously reported neuroplasticity changes after peripheral lesions in animals and humans. In striking contradistinction, vibratory stimulation of the foot evoked topographically appropriate responses in SI and second somatosensory cortex (SII). Motor cortex responses, tied to a visuomotor tracking task, displayed a neartypical topography, although they were more widespread in premotor regions. These findings suggest possible preservation of motor and some somatosensory cortical representations in the absence of overt movements or conscious sensations for several years after spinal cord injury and have implications for future rehabilitation and neural-repair therapies. Severe sensory deprivation due to amputation or peripheral nerve damage profoundly alters responsiveness and topographical organization of primary somatosensory cortex (SI) (see reviews in refs. 1-3). Less well known are the alterations in cortical responses after spinal cord injury (SCI). Individuals with SCI, as opposed to those with amputations, retain a normal body, which may influence cortical reorganization significantly, especially in individuals with partial SCI who have surviving fibers and potentially some functional connections across the level of damage. It will become an important practical issue to assess cortical responsiveness immediately after damage and in the course of recovery if ongoing efforts for restoring function by transplantation or other means are successful (4). Functional MRI (fMRI) with blood oxygenation level-dependent (BOLD) contrast provides a noninvasive method to assess neuronal activity by monitoring task-related changes in the local tissue concentration of deoxyhemoglobin (5).In this fMRI study we mapped cortical somatosensory-motor areas in a subject with a high cervical traumatic injury at the level of the second cervical vertebra (C2). This subject had complete loss of motor and sensory function below the C3 level except for spotty sensation in the left hemibody for 5 years after injury and then progressively regained some capabilities in years 6-8. This late partial recovery was unexpected and followed a regimen of physical therapy that was more vigorous, frequent, and prolonged than is usual in most SCI patients (6). This study sought to determine t...

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Section: Resultssupporting

confidence: 75%

Functional reorganization and stability of somatosensory-motor cortical topography in a tetraplegic subject with late recovery

Corbetta

Burton

Sinclair

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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“…The stimulus intensities were determined based on the metric defined in Ioannides et al (2002a,b). Briefly, before the experiment, we defined two basic intensity thresholds for both wrists: motor threshold (MTH) as the minimal stimulus intensity producing thumb twitching and sensory threshold (STH) as the minimal stimulus intensity at which the subject was just able to feel a train of stimulus pulses, repeated four times.…”

Section: Methodsmentioning

confidence: 99%

MEG reveals a fast pathway from somatosensory cortex to occipital areas via posterior parietal cortex in a blind subject

Ioannides¹,

Liu²,

Poghosyan³

et al. 2013

Front. Hum. Neurosci.

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Cross-modal activity in visual cortex of blind subjects has been reported during performance of variety of non-visual tasks. A key unanswered question is through which pathways non-visual inputs are funneled to the visual cortex. Here we used tomographic analysis of single trial magnetoencephalography (MEG) data recorded from one congenitally blind and two sighted subjects after stimulation of the left and right median nerves at three intensities: below sensory threshold, above sensory threshold and above motor threshold; the last sufficient to produce thumb twitching. We identified reproducible brain responses in the primary somatosensory (S1) and motor (M1) cortices at around 20 ms post-stimulus, which were very similar in sighted and blind subjects. Time-frequency analysis revealed strong 45–70 Hz activity at latencies of 20–50 ms in S1 and M1, and posterior parietal cortex Brodmann areas (BA) 7 and 40, which compared to lower frequencies, were substantially more pronounced in the blind than the sighted subjects. Critically, at frequencies from α-band up to 100 Hz we found clear, strong, and widespread responses in the visual cortex of the blind subject, which increased with the intensity of the somatosensory stimuli. Time-delayed mutual information (MI) revealed that in blind subject the stimulus information is funneled from the early somatosensory to visual cortex through posterior parietal BA 7 and 40, projecting first to visual areas V5 and V3, and eventually V1. The flow of information through this pathway occurred in stages characterized by convergence of activations into specific cortical regions. In sighted subjects, no linked activity was found that led from the somatosensory to the visual cortex through any of the studied brain regions. These results provide the first evidence from MEG that in blind subjects, tactile information is routed from primary somatosensory to occipital cortex via the posterior parietal cortex.

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“…Such "generators" may also be found in the spinal cord caudal to the lesion (Wang et al, 2005). Cortical activation has been recorded following stimulation of a region below the level of a "complete injury", which suggests the presence of some surviving ascending projection axons or the existence of an alternate "sensory" pathway that bypasses the injury (Ioannides et al, 2002). Presently, the evidence supporting the existence of such a "neural bridge" following complete transection is rather weak based on behavioral and histological data (Basso et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Expansion of formalin-evoked Fos-immunoreactivity in rats with a spinal cord injury

Castellanos

Daniels

Morales

et al. 2007

Neuroscience Research

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Peripheral tissue injury as well as spinal cord injury (SCI) may lead to sensitization of dorsal horn neurons and alterations in nociceptive processing. Thus, peripheral injuries experienced by SCI patients, even if not initially perceived, could result in a persistent and widespread activation of dorsal horn neurons and emerge as chronic pain with interventive repair or modest recovery from SCI. To visualize the spinal neuron response to peripheral tissue injury following complete SCI in rats, the neural transcription factor Fos was quantitated in the spinal cord. Two weeks following either a complete transection of the spinal cord at the level of T8 or a sham surgery (laminectomy), rats were injected with formalin into the left hind paw. Sham-operated rats demonstrated biphasic hind paw pain-related behavior following formalin injection, but transected rats displayed fewer behaviors in the second (tonic) phase. Stereological analysis of the sham group revealed that the extent of formalininduced Fos expression was within the lumbar dorsal horn, with numerous Fos-like immunoreactive profiles in the ipsilateral dorsal horn and some contralateral immunoreactive profiles. In contrast, the level of Fos-like immunoreactivity in the transected group was significantly elevated and expanded in range compared to the sham group, with increases observed in the normal laminar distribution regions, as well as multisegmentally through sacral levels and increases in the contralateral dorsal horn segments. The data demonstrate that widespread activation of spinal, especially dorsal horn, neurons following peripheral insult can occur in the injured spinal cord, despite reduced pain responsiveness, and suggests that exaggerated pain may emerge as spinal recovery or repair progresses.

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Brain Activation Sequences Following Electrical Limb Stimulation of Normal and Paraplegic Subjects

Cited by 18 publications

References 36 publications

Functional reorganization and stability of somatosensory-motor cortical topography in a tetraplegic subject with late recovery

Functional reorganization and stability of somatosensory-motor cortical topography in a tetraplegic subject with late recovery

MEG reveals a fast pathway from somatosensory cortex to occipital areas via posterior parietal cortex in a blind subject

Expansion of formalin-evoked Fos-immunoreactivity in rats with a spinal cord injury

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