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Cerebral Activation (cerebral + activation)
Selected AbstractsCerebral activation by fasting induces lactate accumulation in the hypothalamusMAGNETIC RESONANCE IN MEDICINE, Issue 2 2009Inês R. Violante Abstract Carbon-13 (13C) high-resolution magic angle spinning (HR-MAS) spectroscopy was used to investigate the neuroglial coupling mechanisms underlying appetite regulation in the brain of C57BL/6J mice metabolizing [1- 13C]glucose. Control fed or overnight fasted mice received [1- 13C]glucose (20 ,mol/g intraperitoneally [i.p.]), 15 min prior to brain fixation by focused microwaves. The hypothalamic region was dissected from the rest of the brain and 13C HR-MAS spectra were obtained from both biopsies. Fasting resulted in a significant increase in hypothalamic [3- 13C]lactate and [2- 13C],-aminobutyric acid (GABA) relative to the remaining brain. Administration of the orexigenic peptide ghrelin (0.3 nmol/g i.p.) did not increase hypothalamic [3- 13C]lactate or [2- 13C]GABA, suggesting that ghrelin signaling is not sufficient to elicit all the metabolic consequences of hypothalamic activation by fasting. Our results indicate that the hypothalamic regulation of appetite involves, in addition to the well-known neuropeptide signaling, increased neuroglial lactate shuttling and augmented GABA concentrations. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Brief breath holding may confound functional magnetic resonance imaging studiesHUMAN BRAIN MAPPING, Issue 4 2005David F. Abbott Abstract We demonstrate that breath holding of short durations may confound functional magnetic resonance imaging (fMRI) studies. Some subjects may hold their breath for a short time during task performance, especially if the task is challenging. Breath holding may therefore need to be considered specifically when interpreting fMRI experiments. We studied the temporal and spatial characteristics of cerebral T2*-weighted signal during short periods of breath holding by seven individuals in a 3-tesla MR scanner. We demonstrate that breath-holds as short as 3 s can result in regions of significant cerebral activation. More interestingly, we show that focal activation remains present when the data is analysed in a number of different ways, including analyses that correct for motion and model the task epoch as if it were 10 times longer than the actual breath-hold length. These findings have potential relevance for many researchers carrying out fMRI studies. Hum. Brain Mapping 24:284,290, 2005. © 2005 Wiley-Liss, Inc. [source] Lie detection by functional magnetic resonance imagingHUMAN BRAIN MAPPING, Issue 3 2002Tatia M.C. Lee Abstract The accurate detection of deception or lying is a challenge to experts in many scientific disciplines. To investigate if specific cerebral activation characterized feigned memory impairment, six healthy male volunteers underwent functional magnetic resonance imaging with a block-design paradigm while they performed forced-choice memory tasks involving both simulated malingering and under normal control conditions. Malingering that demonstrated the existence and involvement of a prefrontal-parietal-sub-cortical circuit with feigned memory impairment produced distinct patterns of neural activation. Because astute liars feign memory impairment successfully in testing once they understand the design of the measure being employed, our study represents an extremely significant preliminary step towards the development of valid and sensitive methods for the detection of deception. Hum. Brain Mapping 15:157,164, 2002. © 2002 Wiley-Liss, Inc. [source] A Method for the Automated Assessment of Temporal Characteristics of Functional Hemispheric Lateralization by Transcranial Doppler SonographyJOURNAL OF NEUROIMAGING, Issue 3 2004M. Deppe ABSTRACT Background and Purpose. Transcranial Doppler sonography (TCD) can guide and complement investigations based on functional magnetic resonance and positron emission tomography imaging by providing continuous information on cerebral perfusion changes correlated to cerebral activation. So far, however, the role of functional TCD has been limited by a lack of sensitivity.Methods. Here, the authors present an outline of a method that increases the potential of TCD to detect perfusion changes within a vascular territory. Sensitivity on the order of 1% can be achieved by transformation of Doppler envelope curves, which accounts for systemic quasi-periodic and irregular spontaneous blood flow modulations and artificial disturbances related to the recording. A statistical technique is introduced that allows the automatic detection of time periods of significant hemispheric lateralization in evoked flow studies. Furthermore, an index of laterality is defined quantifying the extent of hemispheric dominance during stimulus processing.Results and Discussion. The analysis technique described in this article has been successfully employed in recent examinations on vision, motor activation, language, language recovery, and other cognitive tasks. Conclusion. The novel functional TCD technique permits valid and reproducible assessments of the temporal characteristics of functional hemispheric lateralization. [source] Arterial spin labeling demonstrates that focal amygdalar glutamatergic agonist infusion leads to rapid diffuse cerebral activationACTA NEUROLOGICA SCANDINAVICA, Issue 3 2010J. P. Munasinghe Munasinghe JP, Banerjee M, Acosta MT, Banks M, Heffer A, Silva AC, Koretsky A, Theodore WH. Arterial spin labeling demonstrates that focal amygdalar glutamatergic agonist infusion leads to rapid diffuse cerebral activation. Acta Neurol Scand: 2010: 121: 209,216. © 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Objectives,,, To investigate acute effects of intra-amygdalar excitatory amino acid administration on blood flow, relaxation time and apparent diffusion coefficient in rat brain. Materials and methods,,, Several days after MR-compatible cannula placement in right basolateral amygdala, anesthetized rats were imaged at 7 T. Relative cerebral blood flow (CBF) was measured before and 60 min after infusion of 10 nmol KA, cAMPA, ATPA, or normal saline using arterial spin labeling. Quantitative T2 and diffusion-weighted images were acquired. rCBF, T2 and ADC values were evaluated in bilateral basolateral amygdala, hippocampus, basal ganglia, frontal and parietal regions. Results,,, KA led to the highest, and ATPA lowest bilateral rCBF increases. Time courses varied among drugs. T2 for KA and AMPA was higher while ADC was lower for KA. Conclusions,,, Intra-amygdalar injection of GluR agonists evoked bilateral seizure activity and increased rCBF, greater for KA and AMPA than selective ATPA GluR5 activation. [source] | ||||||||||