Optical imaging spectroscopy in the unanaesthetised rat

Martin, Chris; Berwick, Jason; Johnston, Dave; Zheng, Ying; Martindale, John; Port, Michael; Redgrave, Peter; Mayhew, John E. W.

doi:10.1016/s0165-0270(02)00185-1

Cited by 51 publications

(38 citation statements)

References 20 publications

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“…This result could be expected given the depressive effects of anesthetics on imaging higher-order and association areas, making those areas difficult to study in anesthetized animals; this provides additional motivation for developing methods for studying population response in awake, behaving animals [in monkey parietal cortex (cf. Siegel et al, 2003); in monkey prefrontal cortex (Siedemann et al, 2002;Roe, 2004); in rat barrel cortex Martin et al, 2002;Sachdev et al, 2003)]. In the awake animal, we found the activation ratio between areas 3b and 1 reverses such that area 1 is dominant over area 3b.…”

Section: Shift Of Areal Dominancementioning

confidence: 48%

Optical Imaging of SI Topography in Anesthetized and Awake Squirrel Monkeys

2005

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Orderly topographic maps in the primary somatosensory cortex (SI) serve as an anchor for our understanding of somatosensory cortical organization. However, this view is mostly based on data collected in the anesthetized animal. Less is known about these topographies in the awake primate. Even less is known about the relative activations of different subdivisions of SI (areas 3a, 3b, 1, and 2). Toward the goal of understanding the functional activation of SI, we conducted intrinsic signal optical imaging of areas 3b and 1 in awake squirrel monkeys. Monkeys were imaged repeatedly for a period of Ͼ2 years in awake and anesthetized states in response to vibrotactile and electrocutaneous stimuli presented to individual fingerpads. During this period, we found stable somatotopic maps in both the anesthetized and awake states, consistent with electrophysiologically recorded maps in areas 3b and 1 in the anesthetized state. In the awake animal, signal sizes were larger, but variability was greater, leading to decreased signal-to-noise ratios. Topographic activations were larger (in both area and amplitude) in the awake animal, suggesting either a less precise topography and/or more complex integration. This brings into question the role of a precise topographic map during behavior. In addition, whereas in the anesthetized animal strongest imaging signals were obtained from area 3b, in the awake animal, area 1 activation dominated over that in area 3b. Differences in relative dominance of area 3b versus area 1 suggest that inter-areal interactions in the alert animal differ substantially from that in the anesthetized animal.

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Section: Shift Of Areal Dominancementioning

confidence: 48%

Optical Imaging of SI Topography in Anesthetized and Awake Squirrel Monkeys

2005

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“…In addition to this highly organized neuronal connectivity, the blood supply of each barrel is also functionally compartmentalized (Cox et al, 1993). Following vibrissae stimulation, brain imaging studies have visualized local increases in CBF in the barrels corresponding to the stimulated whiskers (Martin et al, 2002;Dunn et al, 2005;Berwick et al, 2008). Given the robustness of this paradigm, it has been used to identify several mediators of the evoked CBF response (for review, see Koehler et al, 2009;Cauli and Hamel, 2010).…”

Section: Introductionmentioning

confidence: 99%

Pyramidal Neurons Are "Neurogenic Hubs" in the Neurovascular Coupling Response to Whisker Stimulation

Lecrux

Toussay

Kocharyan

et al. 2011

Journal of Neuroscience

156

165

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The whisker-to-barrel cortex is widely used to study neurovascular coupling, but the cellular basis that underlies the perfusion changes is still largely unknown. Here, we identified neurons recruited by whisker stimulation in the rat somatosensory cortex using double immunohistochemistry for c-Fos and markers of glutamatergic and GABAergic neurons, and investigated in vivo their contribution along with that of astrocytes in the evoked perfusion response. Whisker stimulation elicited cerebral blood flow (CBF) increases concomitantly with c-Fos upregulation in pyramidal cells that coexpressed cyclooxygenase-2 (COX-2) and GABA interneurons that coexpressed vasoactive intestinal polypeptide and/or choline acetyltransferase, but not somatostatin or parvalbumin. The evoked CBF response was decreased by blockade of NMDA (MK-801, Ϫ37%), group I metabotropic glutamate (MPEPϩLY367385, Ϫ40%), and GABA-A (picrotoxin, Ϫ31%) receptors, but not by GABA-B, VIP, or muscarinic receptor antagonism. Picrotoxin decreased stimulus-induced somatosensory evoked potentials and CBF responses. Combined blockade of GABA-A and NMDA receptors yielded an additive decreasing effect (Ϫ61%) of the evoked CBF compared with each antagonist alone, demonstrating cooperation of both excitatory and inhibitory systems in the hyperemic response. Blockade of prostanoid synthesis by inhibiting COX-2 (indomethacin, NS-398), expressed by ϳ40% of pyramidal cells but not by astrocytes, impaired the CBF response (Ϫ50%). The hyperemic response was also reduced (Ϫ40%) after inhibition of astroglial oxidative metabolism or epoxyeicosatrienoic acids synthesis. These results demonstrate that changes in pyramidal cell activity, sculpted by specific types of inhibitory GABA interneurons, drive the CBF response to whisker stimulation and, further, that metabolically active astrocytes are also required.

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“…Anesthesia significantly affects the physiological state including the regulation of cerebral circulation throughout the brain [1][2][3][4][5][6]. Only a small number of fMRI studies under awake conditions have Abbreviations: BOLD, Blood Oxygenation Level Dependent; E, Entopallium; FC, functional connectivity; GLd, nucleus geniculatus lateralis pars dorsalis; ROI, region of interest; rsfMRI, resting state functional magnetic resonance imaging; Rt, nucleus rotundus; TE, echo time; TR, repetition time.…”

Section: Introductionmentioning

confidence: 99%

Functional MRI and functional connectivity of the visual system of awake pigeons

Groof

Jonckers

Güntürkün

et al. 2013

Behavioural Brain Research

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h i g h l i g h t sFirst study to image the whole brain of awake pigeons. We show a habituation program for MR-sessions under awake and head-fixed conditions. Movement under these conditions is minimal. First measurement of functional connectivity in a non-mammalian species. Analyses of BOLD-response and functional connectivity are feasible. a r t i c l e i n f o b s t r a c tAt present, functional MRI (fMRI) is increasingly used in animal research but the disadvantage is that the majority of the imaging is applied in anaesthetized animals. Only a few articles present results obtained in awake rodents. In this study both traditional fMRI and resting state (rsfMRI) were applied to four pigeons, that were trained to remain still while being imaged, removing the need for anesthesia. This is the first time functional connectivity measurements are performed in a non-mammalian species. Since the visual system of pigeons is a well-known model for brain asymmetry, the focus of the study was on the neural substrate of the visual system. For fMRI a visual stimulus was used and functional connectivity measurements were done with the entopallium (E; analog for the primary visual cortex) as a seed region. Interestingly in awake pigeons the left E was significantly functionally connected to the right E. Moreover we compared connectivity maps for a seed region in both hemispheres resulting in a stronger bilateral connectivity starting from left E then from right E. These results could be used as a starting point for further imaging studies in awake birds and also provide a new window into the analysis of hemispheric dominance in the pigeon.

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Optical imaging spectroscopy in the unanaesthetised rat

Cited by 51 publications

References 20 publications

Optical Imaging of SI Topography in Anesthetized and Awake Squirrel Monkeys

Optical Imaging of SI Topography in Anesthetized and Awake Squirrel Monkeys

Pyramidal Neurons Are "Neurogenic Hubs" in the Neurovascular Coupling Response to Whisker Stimulation

Functional MRI and functional connectivity of the visual system of awake pigeons

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