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Qi HX, Wang F, Liao CC, Friedman RM, Tang C, Kaas JH, Avison MJ. Spatiotemporal trajectories of reactivation of somatosensory cortex by direct and secondary pathways after dorsal column lesions in squirrel monkeys. Neuroimage 2016; 142:431-453. [PMID: 27523450 DOI: 10.1016/j.neuroimage.2016.08.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/23/2016] [Accepted: 08/09/2016] [Indexed: 11/17/2022] Open
Abstract
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 cerebral blood volume-based functional magnetic resonance imaging (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 6weeks after a mid-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 2weeks post-lesion, and their spatio-temporal trajectories of recovery between 2 and 6weeks. Similar variations in the silencing and recovery of somatotopy and responsiveness to high intensity ES in areas 3a and 1 are consistent with individual differences in damage to and recovery of DC and spinocuneate pathways, and possibly the potentiation of 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.
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Affiliation(s)
- Hui-Xin Qi
- Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA.
| | - Feng Wang
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37240, USA; Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37240, USA
| | - Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA
| | - Robert M Friedman
- Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA
| | - Chaohui Tang
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37240, USA; Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37240, USA
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA; Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37240, USA
| | - Malcolm J Avison
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37240, USA; Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37240, USA; Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
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Galante A, Sinibaldi R, Conti A, De Luca C, Catallo N, Sebastiani P, Pizzella V, Romani GL, Sotgiu A, Della Penna S. Fast Room Temperature Very Low Field-Magnetic Resonance Imaging System Compatible with MagnetoEncephaloGraphy Environment. PLoS One 2015; 10:e0142701. [PMID: 26630172 PMCID: PMC4668052 DOI: 10.1371/journal.pone.0142701] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 10/26/2015] [Indexed: 11/18/2022] Open
Abstract
In recent years, ultra-low field (ULF)-MRI is being given more and more attention, due to the possibility of integrating ULF-MRI and Magnetoencephalography (MEG) in the same device. Despite the signal-to-noise ratio (SNR) reduction, there are several advantages to operating at ULF, including increased tissue contrast, reduced cost and weight of the scanners, the potential to image patients that are not compatible with clinical scanners, and the opportunity to integrate different imaging modalities. The majority of ULF-MRI systems are based, until now, on magnetic field pulsed techniques for increasing SNR, using SQUID based detectors with Larmor frequencies in the kHz range. Although promising results were recently obtained with such systems, it is an open question whether similar SNR and reduced acquisition time can be achieved with simpler devices. In this work a room-temperature, MEG-compatible very-low field (VLF)-MRI device working in the range of several hundred kHz without sample pre-polarization is presented. This preserves many advantages of ULF-MRI, but for equivalent imaging conditions and SNR we achieve reduced imaging time based on preliminary results using phantoms and ex-vivo rabbits heads.
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Affiliation(s)
- Angelo Galante
- MESVA, Department of Life, Health & Environmental Sciences, L'Aquila University, Via Vetoio 10, Coppito, L'Aquila 67100, Italy
- Laboratori Nazionali del Gran Sasso, Istituto Nazionale di Fisica Nucleare, S.S. 17 bis km 18910, Assergi, L'Aquila 67010, Italy
- * E-mail:
| | - Raffaele Sinibaldi
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio" University, Chieti 66100, Italy
| | - Allegra Conti
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio" University, Chieti 66100, Italy
| | - Cinzia De Luca
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio" University, Chieti 66100, Italy
| | - Nadia Catallo
- MESVA, Department of Life, Health & Environmental Sciences, L'Aquila University, Via Vetoio 10, Coppito, L'Aquila 67100, Italy
| | - Piero Sebastiani
- ITA S.r.l., Zona Industriale di Pile, SS17, Località Boschetto, L'Aquila 67100, Italy
| | - Vittorio Pizzella
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio" University, Chieti 66100, Italy
- Institute of Advanced Biomedical Technologies, G. D'Annunzio" University, Chieti 66100, Italy
| | - Gian Luca Romani
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio" University, Chieti 66100, Italy
- Institute of Advanced Biomedical Technologies, G. D'Annunzio" University, Chieti 66100, Italy
| | - Antonello Sotgiu
- ITA S.r.l., Zona Industriale di Pile, SS17, Località Boschetto, L'Aquila 67100, Italy
| | - Stefania Della Penna
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio" University, Chieti 66100, Italy
- Institute of Advanced Biomedical Technologies, G. D'Annunzio" University, Chieti 66100, Italy
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