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In Vivo Mapping of Cortical Columnar Networks in the Monkey with Focal Electrical and Optical Stimulation.

Roe AW, Chernov MM, Friedman RM, Chen G - Front Neuroanat (2015)

Bottom Line: However, there has been little emphasis on understanding connection patterns between functionally specific cortical columns.These new approaches, when applied systematically on a large scale, will elucidate functionally specific intra-areal and inter-areal network connection patterns.Such functionally specific network data can provide accurate views of brain network topology.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University Hangzhou, China.

ABSTRACT
There are currently largescale efforts to understand the brain as a connection machine. However, there has been little emphasis on understanding connection patterns between functionally specific cortical columns. Here, we review development and application of focal electrical and optical stimulation methods combined with optical imaging and fMRI mapping in the non-human primate. These new approaches, when applied systematically on a large scale, will elucidate functionally specific intra-areal and inter-areal network connection patterns. Such functionally specific network data can provide accurate views of brain network topology.

No MeSH data available.


Functional tract tracing with INS stimulation and fMRI. (A) Increasing INS stimulation intensity produces increasing BOLD response. (B) View of 400 μm fiber optic applied to optical window at D2 location (as determined by optical imaging in different session) in area 3b of somatosensory cortex in a squirrel monkey. The monkey was imaged at 9.4T (Varian Inova Magnet) with a 3 cm surface coil surrounding the optical window. (C) Red arrow indicates the location of apposed optical fiber. INS stimulation (0.4 J/cm2, pulsed trains applied in blocks of 30 s ON, 30 s OFF) at this site produces strong BOLD response at fiber tip as well as at corresponding topographic locations in area 3a and area 1. Coronal slice: voxel 625 μm × 625 μm × 1000 μm.
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Figure 6: Functional tract tracing with INS stimulation and fMRI. (A) Increasing INS stimulation intensity produces increasing BOLD response. (B) View of 400 μm fiber optic applied to optical window at D2 location (as determined by optical imaging in different session) in area 3b of somatosensory cortex in a squirrel monkey. The monkey was imaged at 9.4T (Varian Inova Magnet) with a 3 cm surface coil surrounding the optical window. (C) Red arrow indicates the location of apposed optical fiber. INS stimulation (0.4 J/cm2, pulsed trains applied in blocks of 30 s ON, 30 s OFF) at this site produces strong BOLD response at fiber tip as well as at corresponding topographic locations in area 3a and area 1. Coronal slice: voxel 625 μm × 625 μm × 1000 μm.

Mentions: Having characterized the effects of INS stimulation, we next examined whether it could be used as a tool for functional tract tracing. To further motivate the use of this approach, we examined the compatibility of INS with fMRI (Chen et al., 2012c). With fMRI, similar to hemodynamic signals measured with optical imaging, the relationship of INS intensity is proportional to hemodynamic BOLD response (Figure 6A). Preliminary studies in squirrel monkeys implanted with optical chambers over somatosensory cortex (imaged with surface coil in a 9.4T Varian magnet) have shown that targeted stimulation of single digit locations (e.g., D2 tip) via apposition of the stimulating fiber optic to the cortical surface at one somatosensory cortical location (Figure 6B) leads to significant BOLD response in topographically appropriate locations in nearby areas (Figure 6C). When imaged in coronal slices, activations appear localized to superficial or middle layers of cortical laminae, suggesting that this resolution is sufficient for superficial, middle, or deep laminar localization (Figure 6C). INS combined with fMRI thus provides the opportunity to examine intra- and inter-areal connection patterns of a stimulated site, as well as identify resulting laminar profiles, that will be useful for interpretation of feedforward or feedback connection patterns.


In Vivo Mapping of Cortical Columnar Networks in the Monkey with Focal Electrical and Optical Stimulation.

Roe AW, Chernov MM, Friedman RM, Chen G - Front Neuroanat (2015)

Functional tract tracing with INS stimulation and fMRI. (A) Increasing INS stimulation intensity produces increasing BOLD response. (B) View of 400 μm fiber optic applied to optical window at D2 location (as determined by optical imaging in different session) in area 3b of somatosensory cortex in a squirrel monkey. The monkey was imaged at 9.4T (Varian Inova Magnet) with a 3 cm surface coil surrounding the optical window. (C) Red arrow indicates the location of apposed optical fiber. INS stimulation (0.4 J/cm2, pulsed trains applied in blocks of 30 s ON, 30 s OFF) at this site produces strong BOLD response at fiber tip as well as at corresponding topographic locations in area 3a and area 1. Coronal slice: voxel 625 μm × 625 μm × 1000 μm.
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Figure 6: Functional tract tracing with INS stimulation and fMRI. (A) Increasing INS stimulation intensity produces increasing BOLD response. (B) View of 400 μm fiber optic applied to optical window at D2 location (as determined by optical imaging in different session) in area 3b of somatosensory cortex in a squirrel monkey. The monkey was imaged at 9.4T (Varian Inova Magnet) with a 3 cm surface coil surrounding the optical window. (C) Red arrow indicates the location of apposed optical fiber. INS stimulation (0.4 J/cm2, pulsed trains applied in blocks of 30 s ON, 30 s OFF) at this site produces strong BOLD response at fiber tip as well as at corresponding topographic locations in area 3a and area 1. Coronal slice: voxel 625 μm × 625 μm × 1000 μm.
Mentions: Having characterized the effects of INS stimulation, we next examined whether it could be used as a tool for functional tract tracing. To further motivate the use of this approach, we examined the compatibility of INS with fMRI (Chen et al., 2012c). With fMRI, similar to hemodynamic signals measured with optical imaging, the relationship of INS intensity is proportional to hemodynamic BOLD response (Figure 6A). Preliminary studies in squirrel monkeys implanted with optical chambers over somatosensory cortex (imaged with surface coil in a 9.4T Varian magnet) have shown that targeted stimulation of single digit locations (e.g., D2 tip) via apposition of the stimulating fiber optic to the cortical surface at one somatosensory cortical location (Figure 6B) leads to significant BOLD response in topographically appropriate locations in nearby areas (Figure 6C). When imaged in coronal slices, activations appear localized to superficial or middle layers of cortical laminae, suggesting that this resolution is sufficient for superficial, middle, or deep laminar localization (Figure 6C). INS combined with fMRI thus provides the opportunity to examine intra- and inter-areal connection patterns of a stimulated site, as well as identify resulting laminar profiles, that will be useful for interpretation of feedforward or feedback connection patterns.

Bottom Line: However, there has been little emphasis on understanding connection patterns between functionally specific cortical columns.These new approaches, when applied systematically on a large scale, will elucidate functionally specific intra-areal and inter-areal network connection patterns.Such functionally specific network data can provide accurate views of brain network topology.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University Hangzhou, China.

ABSTRACT
There are currently largescale efforts to understand the brain as a connection machine. However, there has been little emphasis on understanding connection patterns between functionally specific cortical columns. Here, we review development and application of focal electrical and optical stimulation methods combined with optical imaging and fMRI mapping in the non-human primate. These new approaches, when applied systematically on a large scale, will elucidate functionally specific intra-areal and inter-areal network connection patterns. Such functionally specific network data can provide accurate views of brain network topology.

No MeSH data available.