title: Altered Spatiotemporal Dynamics of Cortical Activation to Tactile Stimuli in Somatosensory Area 3b and Area 1 of Monkeys after Spinal Cord Injury.
abstract: Reactivation of deafferented cortex plays a key role in mediating the recovery of lost functions, although the precise mechanism is not fully understood. This study simultaneously characterized the dynamic spatiotemporal features of tactile responses in areas 3b and 1 before and 6-8 weeks after partial dorsal column lesion (DCL), and examined how the reactivation relates to the recovery of simple hand use in squirrel monkeys. A combination of high spatiotemporal resolution functional intrinsic optical imaging, microelectrode mapping, behavioral assessment, and tracer histology methods were used. Compared with the normal cortex, we found that the responses of deafferented areas 3b and 1 to 3 s of continuous 8 Hz tactile stimulation of a single digit were significantly weaker and more transient. This finding indicates a loss of response to sustained tactile stimuli. The activation area enlarged for areas 3b and 1 in both directions along digit representation (medial-lateral) and across areas (anterior-posterior). All subjects showed behavioral deficits in a food reaching-grasping-retrieving task within the first 5 weeks after DCL, but recovered at the time when optical images were acquired. Summarily, we showed that these populations of cortical neurons responded to peripheral tactile inputs, albeit in significantly altered manners in each area, several weeks after deafferentation. We propose that compromised ascending driven inputs, impaired lateral inhibition, and local integration of input signals may account for the altered spatiotemporal dynamics of the reactivated areas 3b and 1 cortices. Further investigation with large sample sizes is needed to fully characterize the effects of deafferentation on area 1 activation size.
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232; Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences/State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan, People's Republic of China 430071.
authors.forename: Ruiqi
authors.identifier: 0000-0002-6333-0862
authors.initials: R
authors.lastname: Wu
authors.affiliation: Psychology Undergraduate Program, Duke University , Durham, North Carolina 27708.
authors.forename: Langting
authors.initials: L
authors.lastname: Su
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232.
authors.forename: Pai-Feng
authors.identifier: 0000-0003-0265-4772
authors.initials: PF
authors.lastname: Yang
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232; Department of Psychology, Vanderbilt University, Nashville, Tennessee 37232.
authors.forename: Li
authors.initials: L
authors.lastname: Min Chen
mesh_terms: D000818:Animals; D006225:Hand / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000502:physiology; D010812:Physical Stimulation; D020127:Recovery of Function / Q000502:physiology*; D012453:Saimiri; D013003:Somatosensory Cortex / Q000473:pathology / Q000503:physiopathology*; D013116:Spinal Cord / Q000473:pathology / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology*; D055698:Touch Perception / Q000502:physiology*
keywords: deafferentation; dorsal column lesion; hand; new world monkeys; touch