Intracortical connections are altered after long‐standing deprivation of dorsal column inputs in the hand region of area 3b in squirrel monkeys

Liao, Chia‐Chi; Reed, Jamie L.; Kaas, Jon H.; Qi, Hui‐Xin

doi:10.1002/cne.23921

Cited by 28 publications

(45 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, the neural activity in the deafferented limb representation in SI through face stimulation is abolished when the cuneate nucleus is inactivated [54]. This suggests that projections from the trigeminal nucleus – which receives signals from the face – to the cuneate nucleus – which receives signals from the limb – become potentiated or actually sprout after the cuneate nucleus is deafferented [55,56] (Figure 1A; see [56] for evidence of the formation of alternative somatosensory pathways). In fact, there is little anatomical evidence that the face-elicited activity in SI is mediated by the growth of new cortico-cortical projections: Very few axons cross the face–hand boundary in SI of intact animals (see [57] for analogous results in humans revealed with neuroimaging) and deafferentation of the hand region does not result in any measurable increase in these boundary-crossing projections [58].…”

Section: Neural Basis Of Reorganisationmentioning

confidence: 99%

Stability of Sensory Topographies in Adult Cortex

Makin

Bensmaı̈a

2017

Trends in Cognitive Sciences

109

View full text Add to dashboard Cite

Textbooks teach us that the removal of sensory input to sensory cortex, for example, following arm amputation, results in massive reorganisation in the adult brain. In this opinion article, we critically examine evidence for functional reorganisation of sensory cortical representations, focusing on the sequelae of arm amputation on somatosensory topographies. Based on literature from human and non-human primates, we conclude that the cortical representation of the limb remains remarkably stable despite the loss of its main peripheral input. Furthermore, the purportedly massive reorganisation results primarily from the formation or potentiation of new pathways in subcortical structures and does not produce novel functional sensory representations. We discuss the implications of the stability of sensory representations on the development of upper-limb neuroprostheses.

show abstract

Section: Neural Basis Of Reorganisationmentioning

confidence: 99%

Stability of Sensory Topographies in Adult Cortex

Makin

Bensmaı̈a

2017

Trends in Cognitive Sciences

109

View full text Add to dashboard Cite

show abstract

“…Some of this reactivation may originate from those few primary afferents that often survive such spinal cord lesions. However the spared afferents of the second order spinal cord neurons that normally provide sub-threshold or modulatory inputs to the cuneate nucleus may also become an effective source of cortical reactivation (Liao et al, 2015). The importance of these secondary inputs may increase with increasing severity of primary deafferentation.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal trajectories of reactivation of somatosensory cortex by direct and secondary pathways after dorsal column lesions in squirrel monkeys

Wang

Liao

et al. 2016

NeuroImage

Self Cite

View full text Add to dashboard Cite

After lesions of the somatosensory dorsal column (DC) pathway, the cortical hand representation can become unresponsive to tactile stimuli, but considerable responsiveness returns over weeks of post-lesion recovery. The reactivation suggests that preserved subthreshold sensory inputs become potentiated and axon sprouting occurs over time to mediate recovery. Here, we studied the recovery process in 3 squirrel monkeys, using high-resolution fMRI CBV-fMRI mapping of contralateral somatosensory cortex responsiveness to stimulation of distal finger pads with low and high level electrocutaneous stimulation (ES) before and 2, 4, and 6 weeks after a high cervical level contralateral DC lesion. Both low and high intensity ES of digits revealed the expected somatotopy of the area 3b hand representation in pre-lesion monkeys, while in areas 1 and 3a, high intensity stimulation was more effective in activating somatotopic patterns. Six weeks post-lesion, and irrespective of the severity of loss of direct DC inputs (98%, 79%, 40%), somatosensory cortical area 3b of all three animals showed near complete recovery in terms of somatotopy and responsiveness to low and high intensity ES. However there was significant variability in the patterns and amplitudes of reactivation of individual digit territories within and between animals, reflecting differences in the degree of permanent and/or transient silencing of primary DC and secondary inputs 2 weeks post-lesion, and their spatio-temporal trajectories of recovery between 2 and 6 weeks. Similar variations in the silencing and recovery of somatotopy and responsiveness to high intensity ES in areas 3a and 1 are consistent with inter-individual differences in collateral damage to and recovery of secondary (e.g. spinothalamic) pathways. Thus, cortical deactivation and subsequent reactivation depends not only on the degree of DC lesion, but also on the severity and duration of loss of secondary as well as primary inputs revealed by low and high intensity ES.

show abstract

“…Finally, the remapping reported here may indeed be constrained by proximity between body-part representations -not in the cerebellum/cerebrum, but rather in subcortical sensorimotor terminals. While it has originally been suggested that sensorimotor remapping occurs at the level of the cerebral cortex (Pons et al, 1991;Florence et al, 1998), recent studies in monkeys emphasize the role of subcortical structures, such as the brainstem, in which the layout of somatotopic representations differs from that of the cerebral cortex (Jain et al, 2000;Kambi et al, 2014;Chand and Jain, 2015;Liao et al, 2016). For example, Kambi and colleagues (2014) demonstrated that facial remapping in the deprived cerebral hand region of spinal-cord-injured monkeys is abolished upon inactivation of the deprived cuneate nucleus.…”

Section: Discussionmentioning

confidence: 99%

Remapping in cerebral and cerebellar cortices is not restricted by somatotopy

Hahamy

Makin

2018

Preprint

View full text Add to dashboard Cite

Cardinali for help in data collection, and Victoria Root for helpful comments on the manuscript. We thank Opcare for help with recruitment, and our participants for taking part in these studies.When a hand is missing, the brain region that typically processes information from that hand may instead process information from other body-parts, a phenomenon termed reorganization. It is commonly thought that only body-parts whose information is processed in regions adjacent to the hand region, could take up the resources of this now deprived region. Here we demonstrate that information from the same bodyparts is processed in the hand regions of both the cerebral cortex and cerebellum. The native brain regions of these body-parts have varied relative distances from the hand region of the cerebellum compared to the cerebral cortex, and do not necessarily neighbor these hand regions. We therefore propose that proximity between brain regions cannot fully explain brain reorganization.

show abstract

Intracortical connections are altered after long‐standing deprivation of dorsal column inputs in the hand region of area 3b in squirrel monkeys

Cited by 28 publications

References 76 publications

Stability of Sensory Topographies in Adult Cortex

Stability of Sensory Topographies in Adult Cortex

Spatiotemporal trajectories of reactivation of somatosensory cortex by direct and secondary pathways after dorsal column lesions in squirrel monkeys

Remapping in cerebral and cerebellar cortices is not restricted by somatotopy

Contact Info

Product

Resources

About