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Vaughan G Macefield - One of the best experts on this subject based on the ideXlab platform.

  • Identification of sites of sympathetic outflow at rest and during emotional arousal: Concurrent recordings of sympathetic nerve activity and fMRI of the brain
    International journal of psychophysiology : official journal of the International Organization of Psychophysiology, 2013
    Co-Authors: Vaughan G Macefield, Cheree James, Luke A Henderson
    Abstract:

    The sympathetic nervous system subserves many of the autonomic responses to mental stress and emotional processing. While peripheral markers of sympathetic activity can be obtained indirectly - by measuring heart rate, blood pressure, sweat release and skin blood flow - these effector-organ responses are slower compared to the directly recorded sympathetic nerve activity. Microneurography, in which a tungsten microelectrode is inserted percutaneously into a peripheral nerve in awake human subjects, allows one to record sympathetic nerve activity to either muscle or skin. Muscle sympathetic nerve activity (MSNA) is involved in the beat-to-beat control of blood pressure, and is elevated during mental stress; chronic stress can lead to high blood pressure. The primary role of skin sympathetic nerve activity (SSNA) is to regulate body temperature by controlling sweat release and skin blood flow, but it has also been commandeered for emotional expression. In this review we discuss our recent work in which we have performed concurrent microelectrode recordings of MSNA or SSNA and fMRI of the brain, with a view to identifying areas in the brain responsible for generating the increases in sympathetic outflow at rest and during emotional engagement. Spontaneous bursts of MSNA at rest were positively correlated to activity in the left dorsomedial hypoThalamus and left insula, and bilaterally in the ventromedial hypoThalamus, dorsolateral prefrontal cortex, posterior cingulate cortex and precuneus. Spontaneous bursts of SSNA at rest were positively correlated with activity in the left ventromedial Nucleus of the Thalamus, the left posterior and right anterior insula, the right orbitofrontal and frontal cortices and bilaterally in the mid-cingulate cortex and precuneus. Increases in SSNA occurred when subjects viewed emotionally charged images, resulting in increases in activity in the central and lateral amygdala, dorsolateral pons, Thalamus, Nucleus accumbens, and cerebellar cortex; surprisingly, there was no activation of the insula in response to these emotional stimuli. We have shown that concurrent microelectrode recordings of sympathetic outflow to either muscle or skin and fMRI of the brain can be used to identify areas of the brain involved in the generation of sympathetic nerve activity. We propose that this approach can be extended to examine specific disorders of emotional expression to increase our understanding of the underlying neural processes.

  • real time imaging of cortical areas involved in the generation of increases in skin sympathetic nerve activity when viewing emotionally charged images
    NeuroImage, 2012
    Co-Authors: Luke A Henderson, Alexandra Stathis, Cheree James, Rachael Brown, Skye Mcdonald, Vaughan G Macefield
    Abstract:

    The sympathetic innervation of the skin not only primarily subserves thermoregulation, but has also been commandeered as a means of emotional expression. While the majority of brain imaging studies of emotion have utilised the galvanic skin response as a means of inferring changes in skin sympathetic nerve activity (SSNA), spontaneous fluctuations in the galvanic skin response bear little relation to spontaneous fluctuations in SSNA. To improve our understanding of the central neural processes involved in the generation of autonomic emotional markers, we recorded SSNA concurrently with brain functional magnetic resonance imaging in 13 subjects. Emotional changes were evoked by presentation of positively-charged (erotica) or negatively-charged (mutilation) images from the International Affective Picture System. Positive and negative emotionally-charged images evoked significant increases in total SSNA and signal intensity in the orbital, dorsolateral and ventromedial prefrontal cortices, amygdala, Nucleus accumbens and anterior insula. Increases in signal intensity during increases in SSNA occurred in a number of brain regions, including the central and lateral amygdala, dorsolateral pons, Thalamus, Nucleus accumbens, and cerebellar cortex. Signal intensity decreases during SSNA increases occurred in the left orbitofrontal, frontal and right precuneus cortices. These data reveal for the first time, cortical and subcortical sites involved in generating SSNA changes during emotions.

Michihiro Fujiwara - One of the best experts on this subject based on the ideXlab platform.

  • intracerebral microinjections of δ9 tetrahydrocannabinol search for the impairment of spatial memory in the eight arm radial maze in rats
    Brain Research, 2002
    Co-Authors: Nobuaki Egashira, Katsunori Iwasaki, Kenichi Mishima, Michihiro Fujiwara
    Abstract:

    Abstract The purpose of this study was to identify brain sites that contribute to the Δ9-tetrahydrocannabinol (Δ9-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of Δ9-THC into one of 14 different brain regions. The bilateral microinjection of Δ9-THC (20 μg/side) impaired spatial memory when injected into the dorsal hippocampus (DH), ventral hippocampus (VH) or dorsomedial Thalamus Nucleus (DMT). However, rats treated with Δ9-THC into DMT produced perseverative behavior which has not been observed by systemic administration of Δ9-THC. On the other hand, spatial memory was unaffected by microinjections of Δ9-THC into the other 11 areas examined: frontal (FC) and frontoparietal (FPC) cortex, central (ACE) and basolateral (ABL) amygdaloid Nucleus, medial caudate putamen (CPM), lateral hypoThalamus (LH), mammillary body (MB), basal forebrain (BF), medial septal Nucleus (SEP) and dorsal (DR) and median (MR) raphe Nucleus. These results suggest that DH and VH may be important brain sites for the Δ9-THC-induced impairment of spatial memory.

  • Intracerebral microinjections of Δ9-tetrahydrocannabinol: search for the impairment of spatial memory in the eight-arm radial maze in rats
    Brain research, 2002
    Co-Authors: Nobuaki Egashira, Katsunori Iwasaki, Kenichi Mishima, Michihiro Fujiwara
    Abstract:

    The purpose of this study was to identify brain sites that contribute to the delta(9)-tetrahydrocannabinol (delta(9)-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of delta(9)-THC into one of 14 different brain regions. The bilateral microinjection of delta(9)-THC (20 microg/side) impaired spatial memory when injected into the dorsal hippocampus (DH), ventral hippocampus (VH) or dorsomedial Thalamus Nucleus (DMT). However, rats treated with delta(9)-THC into DMT produced preseverative behavior which has not been observed by systemic administration of delta(9)-THC. On the other hand, spatial memory was unaffected by microinjections of delta(9)-THC into the other 11 areas examined: frontal (FC) and frontoparietal (FPC) cortex, central (ACE) and basolateral (ABL) amygdaloid Nucleus, medial caudate putamen (CPM), lateral hypoThalamus (LH), mammillary body (MB), basal forebrain (BF), medial septal Nucleus (SEP) and dorsal (DR) and median (MR) raphe Nucleus. These results suggest that DH and VH may be important brain sites for the delta(9)-THC-induced impairment of spatial memory.

  • The scopolamine-induced impairment of spatial cognition parallels the acetylcholine release in the ventral hippocampus in rats.
    Japanese journal of pharmacology, 2000
    Co-Authors: Kenichi Mishima, Nobuaki Egashira, Katsunori Iwasaki, Hiroshi Tsukikawa, Yoshiaki Matsumoto, Kohji Abe, Takashi Egawa, Michihiro Fujiwara
    Abstract:

    We investigated the relationship between the induction of spatial cognition impairment in the 8-arm radial maze task and regional changes (ventral hippocampus (VH), dorsal hippocampus, frontal cortex, and basolateral amygdala Nucleus) in brain acetylcholine (ACh) release using microdialysis in rats treated with muscarinic (M) receptor antagonists. In a behavioral study, two M1 antagonists, scopolamine (0.5 mg/kg, i.p. and 20 microg, i.c.v.) and pirenzepine (80 microg, i.c.v.), but not an M2 antagonist, AF-DX116 (40-80 microg, i.c.v.), disrupted spatial cognition in the 8-arm radial maze task. In brain microdialysis with Ringer's solution containing 0.1 mM eserine sulfate, scopolamine and AF-DX116, but not pirenzepine, increased ACh release in the VH. Moreover, in the bilateral injection of scopolamine (2 microg/side), the VH and dorsomedial Thalamus Nucleus were important regions for scopolamine-induced impairment of spatial cognition. A simultaneous determination of the behavioral changes revealed that scopolamine (0.5 mg/kg, i.p.) markedly decreased the ACh contents and also increased the ACh release in all regions tested. Especially, the changes in the ACh release of the VH closely paralleled the induction of the scopolamine-induced impairment of spatial cognition. These results suggest that the blocking balance between M1 and M2 muscarinic receptor in the VH therefore plays a major role in the spatial cognition impairment induced by scopolamine in the 8-arm radial maze task.

Hal Blumenfeld - One of the best experts on this subject based on the ideXlab platform.

  • A pulse of transient fMRI increases in subcortical arousal systems during transitions in attention: Transient pulse in subcortical arousal systems
    NeuroImage, 2021
    Co-Authors: Jun Hwan Ryu, Peter Vincent, Max Springer, Dan Kluger, Erik A. Levinsohn, Yu Chen, He-sheng Chen, Hal Blumenfeld
    Abstract:

    Abstract Studies of attention emphasize cortical circuits for salience monitoring and top-down control. However, subcortical arousal systems have a major influence on dynamic cortical state. We hypothesize that task-related increases in attention begin with a “pulse” in subcortical arousal and cortical attention networks, which may be reflected indirectly through transient fMRI signals. We conducted general linear model and model-free analyses of fMRI data from two cohorts and tasks with mixed block and event-related design. 46 adolescent subjects at our center and 362 normal adults from the Human Connectome Project participated. We identified a core shared network of transient fMRI increases in subcortical arousal and cortical salience/attention networks across cohorts and tasks. Specifically, we observed a transient pulse of fMRI increases both at task block onset and with individual task events in subcortical arousal areas including midbrain tegmentum, Thalamus, Nucleus basalis and striatum; cortical-subcortical salience network regions including the anterior insula/claustrum and anterior cingulate cortex/supplementary motor area; in dorsal attention network regions including dorsolateral frontal cortex and inferior parietal lobule; as well as in motor regions including cerebellum, and left hemisphere hand primary motor cortex. The transient pulse of fMRI increases in subcortical and cortical arousal and attention networks was consistent across tasks and study populations, whereas sustained activity in these same networks was more variable. The function of the transient pulse in these networks is unknown, but given its anatomical distribution, could participate in a neuromodulatory activity surge in multiple parallel neurotransmitter systems facilitating dynamic changes in conscious attention.

Sujit Kumar Sikdar - One of the best experts on this subject based on the ideXlab platform.

  • Tonic current through GABAA receptors and hyperpolarization-activated cyclic nucleotide-gated channels modulate resonance properties of rat subicular pyramidal neurons
    The European journal of neuroscience, 2014
    Co-Authors: Nirnath Sah, Sujit Kumar Sikdar
    Abstract:

    The subiculum, considered to be the output structure of the hippocampus, modulates information flow from the hippocampus to various cortical and sub-cortical areas such as the Nucleus accumbens, lateral septal region, Thalamus, Nucleus gelatinosus, medial Nucleus and mammillary nuclei. Tonic inhibitory current plays an important role in neuronal physiology and pathophysiology by modulating the electrophysiological properties of neurons. While the alterations of various electrical properties due to tonic inhibition have been studied in neurons from different regions, its influence on intrinsic subthreshold resonance in pyramidal excitatory neurons expressing hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is not known. Using pharmacological agents, we show the involvement of α5βγ GABAA receptors in the picrotoxin-sensitive tonic current in subicular pyramidal neurons. We further investigated the contribution of tonic conductance in regulating subthreshold electrophysiological properties using current clamp and dynamic clamp experiments. We demonstrate that tonic GABAergic inhibition can actively modulate subthreshold properties, including resonance due to HCN channels, which can potentially alter the response dynamics of subicular pyramidal neurons in an oscillating neuronal network.

Nobuaki Egashira - One of the best experts on this subject based on the ideXlab platform.

  • intracerebral microinjections of δ9 tetrahydrocannabinol search for the impairment of spatial memory in the eight arm radial maze in rats
    Brain Research, 2002
    Co-Authors: Nobuaki Egashira, Katsunori Iwasaki, Kenichi Mishima, Michihiro Fujiwara
    Abstract:

    Abstract The purpose of this study was to identify brain sites that contribute to the Δ9-tetrahydrocannabinol (Δ9-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of Δ9-THC into one of 14 different brain regions. The bilateral microinjection of Δ9-THC (20 μg/side) impaired spatial memory when injected into the dorsal hippocampus (DH), ventral hippocampus (VH) or dorsomedial Thalamus Nucleus (DMT). However, rats treated with Δ9-THC into DMT produced perseverative behavior which has not been observed by systemic administration of Δ9-THC. On the other hand, spatial memory was unaffected by microinjections of Δ9-THC into the other 11 areas examined: frontal (FC) and frontoparietal (FPC) cortex, central (ACE) and basolateral (ABL) amygdaloid Nucleus, medial caudate putamen (CPM), lateral hypoThalamus (LH), mammillary body (MB), basal forebrain (BF), medial septal Nucleus (SEP) and dorsal (DR) and median (MR) raphe Nucleus. These results suggest that DH and VH may be important brain sites for the Δ9-THC-induced impairment of spatial memory.

  • Intracerebral microinjections of Δ9-tetrahydrocannabinol: search for the impairment of spatial memory in the eight-arm radial maze in rats
    Brain research, 2002
    Co-Authors: Nobuaki Egashira, Katsunori Iwasaki, Kenichi Mishima, Michihiro Fujiwara
    Abstract:

    The purpose of this study was to identify brain sites that contribute to the delta(9)-tetrahydrocannabinol (delta(9)-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of delta(9)-THC into one of 14 different brain regions. The bilateral microinjection of delta(9)-THC (20 microg/side) impaired spatial memory when injected into the dorsal hippocampus (DH), ventral hippocampus (VH) or dorsomedial Thalamus Nucleus (DMT). However, rats treated with delta(9)-THC into DMT produced preseverative behavior which has not been observed by systemic administration of delta(9)-THC. On the other hand, spatial memory was unaffected by microinjections of delta(9)-THC into the other 11 areas examined: frontal (FC) and frontoparietal (FPC) cortex, central (ACE) and basolateral (ABL) amygdaloid Nucleus, medial caudate putamen (CPM), lateral hypoThalamus (LH), mammillary body (MB), basal forebrain (BF), medial septal Nucleus (SEP) and dorsal (DR) and median (MR) raphe Nucleus. These results suggest that DH and VH may be important brain sites for the delta(9)-THC-induced impairment of spatial memory.

  • The scopolamine-induced impairment of spatial cognition parallels the acetylcholine release in the ventral hippocampus in rats.
    Japanese journal of pharmacology, 2000
    Co-Authors: Kenichi Mishima, Nobuaki Egashira, Katsunori Iwasaki, Hiroshi Tsukikawa, Yoshiaki Matsumoto, Kohji Abe, Takashi Egawa, Michihiro Fujiwara
    Abstract:

    We investigated the relationship between the induction of spatial cognition impairment in the 8-arm radial maze task and regional changes (ventral hippocampus (VH), dorsal hippocampus, frontal cortex, and basolateral amygdala Nucleus) in brain acetylcholine (ACh) release using microdialysis in rats treated with muscarinic (M) receptor antagonists. In a behavioral study, two M1 antagonists, scopolamine (0.5 mg/kg, i.p. and 20 microg, i.c.v.) and pirenzepine (80 microg, i.c.v.), but not an M2 antagonist, AF-DX116 (40-80 microg, i.c.v.), disrupted spatial cognition in the 8-arm radial maze task. In brain microdialysis with Ringer's solution containing 0.1 mM eserine sulfate, scopolamine and AF-DX116, but not pirenzepine, increased ACh release in the VH. Moreover, in the bilateral injection of scopolamine (2 microg/side), the VH and dorsomedial Thalamus Nucleus were important regions for scopolamine-induced impairment of spatial cognition. A simultaneous determination of the behavioral changes revealed that scopolamine (0.5 mg/kg, i.p.) markedly decreased the ACh contents and also increased the ACh release in all regions tested. Especially, the changes in the ACh release of the VH closely paralleled the induction of the scopolamine-induced impairment of spatial cognition. These results suggest that the blocking balance between M1 and M2 muscarinic receptor in the VH therefore plays a major role in the spatial cognition impairment induced by scopolamine in the 8-arm radial maze task.