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Challenges of marijuana research

Laura L. Boles Ponto
2006 Brain  
Laura L. Boles Ponto PET Imaging Center University of Iowa Hospitals and Clinics # The Author (2006). Published by Oxford University Press on behalf of the Guarantors of Brain.  ...  In spite of these methodological controls, consistent D 9 -tetrahydrocannabinol (THC) plasma levels between or within subjects may not be achieved (Ponto et al., 2004) , making determination of the dose-response  ... 
doi:10.1093/brain/awl092 pmid:16627464 fatcat:443ummrpejcelleyw33e3um3gq

The cerebellum and emotional experience

Beth M. Turner, Sergio Paradiso, Cherie L. Marvel, Ronald Pierson, Laura L. Boles Ponto, Richard D. Hichwa, Robert G. Robinson
2007 Neuropsychologia  
., 1997; Paradiso, Robinson, Boles Ponto, Watkins, & Hichwa, 2003b; Reiman et al., 1997) or requiring the recognition on an emotion in the face (George et al., 1993) have found increases in cerebellar  ... 
doi:10.1016/j.neuropsychologia.2006.09.023 pmid:17123557 pmcid:PMC1868674 fatcat:wlj6rlkahffddg5xibvvyxhxsy

Eyeblink Conditioning in Healthy Adults: A Positron Emission Tomography Study

Krystal L. Parker, Nancy C. Andreasen, Dawei Liu, John H. Freeman, Laura L. Boles Ponto, Daniel S. O'Leary
2012 Cerebellum  
Eyeblink conditioning is a paradigm commonly used to investigate the neural mechanisms underlying motor learning. It involves the paired presentation of a toneconditioning stimulus which precedes and co-terminates with an airpuff unconditioned stimulus. Following repeated paired presentations a conditioned eyeblink develops which precedes the airpuff. This type of learning has been intensively studied and the cerebellum is known to be essential in both humans and animals. The study presented
more » ... e was designed to investigate the role of the cerebellum during eyeblink conditioning in humans using positron emission tomography (PET). The sample includes 20 subjects (10 male and 10 female) with an average age of 29.2 years. PET imaging was used to measure regional cerebral blood flow (rCBF) changes occurring during the first, second, and third blocks of conditioning. In addition, stimuli-specific rCBF to unpaired tones and airpuffs ("pseudoconditioning") was used as a baseline level that was subtracted from each block. Conditioning was performed using three, 15-trial blocks of classical eyeblink conditioning with the last five trials in each block imaged. As expected, subjects quickly acquired conditioned responses. A comparison between the conditioning tasks and the baseline task revealed that during learning there was activation of the cerebellum and recruitment of several higher cortical regions. Specifically, large peaks were noted in cerebellar lobules IV/V, the frontal lobes, and cingulate gyri.
doi:10.1007/s12311-012-0377-3 pmid:22430943 pmcid:PMC3835594 fatcat:ed4gazc6sne43khoyvasnlsjuq

18F-FDG-PET Imaging for Post-COVID-19 Brain and Skeletal Muscle Alterations

Thorsten Rudroff, Craig D. Workman, Laura L. Boles Ponto
2021 Viruses  
Scientific evidence concerning the subacute and long-term effects of coronavirus disease 2019 (COVID-19) is on the rise. It has been established that infection by serious acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a systemic process that involves multiple organs. The complications and long-term consequences of COVID-19 are diverse and patients need a multidisciplinary treatment approach in the acute and post-acute stages of the disease. A significant proportion of COVID-19
more » ... experience neurological manifestations, some enduring for several months post-recovery. However, brain and skeletal muscle changes resultant from SARS CoV-2 infection remain largely unknown. Here, we provide a brief overview of the current knowledge, and usefulness, of [18F]fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) to investigate brain and skeletal muscles changes in Post-COVID-19 patients with persistent symptoms. Furthermore, a brief discussion of future 18F-FDG-PET/CT applications that might advance the current knowledge of the pathogenesis of post-COVID-19 is also provided.
doi:10.3390/v13112283 pmid:34835088 pmcid:PMC8625263 fatcat:ebm475sq35ezxk7po2cebea56u

Imaging Transcranial Direct Current Stimulation (tDCS) with Positron Emission Tomography (PET)

Thorsten Rudroff, Craig D. Workman, Alexandra C. Fietsam, Laura L. Boles Ponto
2020 Brain Sciences  
Transcranial direct current stimulation (tDCS) is a form of non-invasive neuromodulation that is increasingly being utilized to examine and modify several cognitive and motor functions. Although tDCS holds great potential, it is difficult to determine optimal treatment procedures to accommodate configurations, the complex shapes, and dramatic conductivity differences among various tissues. Furthermore, recent demonstrations showed that up to 75% of the tDCS current applied to rodents and human
more » ... adavers was shunted by the scalp, subcutaneous tissue, and muscle, bringing the effects of tDCS on the cortex into question. Consequently, it is essential to combine tDCS with human neuroimaging to complement animal and cadaver studies and clarify if and how tDCS can affect neural function. One viable approach is positron emission tomography (PET) imaging. PET has unique potential for examining the effects of tDCS within the central nervous system in vivo, including cerebral metabolism, neuroreceptor occupancy, and neurotransmitter activity/binding. The focus of this review is the emerging role of PET and potential PET radiotracers for studying tDCS-induced functional changes in the human brain.
doi:10.3390/brainsci10040236 pmid:32326515 fatcat:25oq35n77zhy3ngd4d3yywcxpq

The neural correlates of implicit sequence learning in schizophrenia

Cherie L. Marvel, Beth M. Turner, Daniel S. O'Leary, Hans J. Johnson, Ronald K. Pierson, Laura L. Boles Ponto, Nancy C. Andreasen
2007 Neuropsychology  
R = right; L = left. Note.  ...  −55, 0, 8 232 .84 L cerebellar Crus II −15, −82, −39 664 −.90 LATE: Block 8 L globus pallidus/putamen −18, 2, 1 128 −.84 L precentral gyrus BA 6 −57, −2, 12 72 .80 L precentral gyrus  ... 
doi:10.1037/0894-4105.21.6.761 pmid:17983290 pmcid:PMC2799042 fatcat:mg4guri43bfuzk2c4l72rzaamu

Neural bases of dysphoria in early Huntington's disease

Sergio Paradiso, Beth M. Turner, Jane S. Paulsen, Ricardo Jorge, Laura L. Boles Ponto, Robert G. Robinson
2008 Psychiatry Research : Neuroimaging  
Psychiatric disorders, including disorders of emotion control, are common in Huntington's disease. The neurobiological mechanism of the increased rate of disorders of emotion control are not known. Emotion perception deficits have been reported in Huntington's disease, but studies of emotional experience have been limited. In the present study we aim to expand the research in emotion in Huntington's disease by examining the neural bases of induced dysphoria at an early stage of Huntington's
more » ... ase. Ten Huntington's disease patients and 12 demographically matched healthy volunteers underwent [ 15 O] water positron emission tomography while in a transient state of dysphoria induced by viewing negatively charged affect-laden stimuli. Both groups experienced dysphoric mood, but Huntington's disease patients responded to the stimuli with greater arousal, anger and fear than healthy controls. Induced dysphoric mood was associated with a widespread reduction of activity within the frontal and parietal lobes, thalamus, and cerebellum. These differences could not be explained based on the smaller gray matter volumes of the corresponding regions, although in Huntington's disease patients smaller caudate nucleus volumes predicted lower dorsal-lateral prefrontal activity. Areas of increased activity included the striate and extrastriate cortex, the left thalamus, the transverse temporal gyrus, and the posterior hippocampus. This study elucidates possible mechanisms contributing to psychiatric disturbances of emotion often found in patients with Huntington's disease. Published by Elsevier Ireland Ltd.
doi:10.1016/j.pscychresns.2007.04.001 pmid:18068955 pmcid:PMC3348657 fatcat:2flia2btxze5dp6srky222m3li

Higher Aortic Stiffness Is Associated With Lower Global Cerebrovascular Reserve Among Older Humans

Lyndsey E. DuBose, Laura L. Boles Ponto, David J. Moser, Emily Harlynn, Leah Reierson, Gary L. Pierce
2018 Hypertension  
Greater aortic stiffness and pulse pressure are associated with cerebrovascular remodeling, reduced white matter microstructure and cognitive performance with aging in humans. However, it is unclear whether aortic stiffness and pulse pressure are associated with reduced basal global cerebral blood flow and cerebrovascular reserve among older adults. Global cerebral blood flow was quantified in 205 adults (range 19-87 yrs; mean ± SE: 30.6 ± 1.3 yrs) using quantitative [ 15 O] water brain PET
more » ... ing. In a subset of older adults (n=24, 70.0 ± 2.0 yrs), aortic stiffness (carotid-femoral pulse wave velocity, PWV) and cerebrovascular reserve (change in global cerebral blood flow following intravenous infusion of acetazolamide) were assessed. In the entire cohort, global cerebral blood flow was lower in older compared with young adults (36.5 ± 1.1 vs. 50.5 ± 0.7 mL/min/100mL, p<0.001). Global cerebral blood flow was higher in young women compared with young men (51.0 ± 0.30 vs. 47.4 ± 0.03 mL/min/100mL, p<0.001) but did not differ between older women and men (p= 0.63). In older adults, greater carotid-femoral PWV was associated with lower cerebrovascular reserve (r= −0.68, p= 0.001 adjusted for age, sex and MAP) but not global cerebral blood flow (r= 0.13, p= 0.60). Brachial pulse pressure was not associated with lower cerebrovascular reserve (r= −0.37, p= 0.159) when adjusted for age and sex. These data indicate that the age-related increases in aortic stiffness may contribute in part to the brain's impaired ability to augment blood flow in response to a stimulus with aging in humans. Summary: Age-related increases in aortic stiffness is associated with reduced CVR, but not basal gCBF, in older adults independent of age, sex, and blood pressure.
doi:10.1161/hypertensionaha.118.11143 pmid:29915015 pmcid:PMC6261448 fatcat:mokq6owfwzduplugiw5wyccdv4

Individual Cerebral Blood Flow Responses to Transcranial Direct Current Stimulation at Various Intensities

Craig D. Workman, Alexandra C. Fietsam, Laura L. Boles Ponto, John Kamholz, Thorsten Rudroff
2020 Brain Sciences  
Transcranial direct current stimulation (tDCS) has been shown to alter cortical excitability. However, it is increasingly accepted that tDCS has high inter- and intra-subject response variability, which currently limits broad application and has prompted some to doubt if the current can reach the brain. This study reports individual cerebral blood flow responses in people with multiple sclerosis and neurologically healthy subjects that experienced 5 min of anodal tDCS at 1 mA, 2 mA, 3 mA, and 4
more » ... mA over either the dorsolateral prefrontal cortex (DLPFC) or the primary motor cortex (M1). The most notable results indicated anticipated changes in regional cerebral blood flow (rCBF) in two regions of one DLPFC subject (2 mA condition), and expected changes in one M1 subject in the 2 mA and 4 mA conditions and in another M1 subject in the 2 mA condition. There were also changes contrary to the expected direction in one DLPFC subject and in two M1 subjects. These data suggest the effects of tDCS might be site-specific and highlight the high variability and individualized responses increasingly reported in tDCS literature. Future studies should use longer stimulation durations and image at various time points after stimulation cessation when exploring the effects of tDCS on cerebral blood flow (CBF).
doi:10.3390/brainsci10110855 pmid:33202753 fatcat:igf7efbdtvd3jblfzuuw43j2ly

Altered Neural Activity and Emotions Following Right Middle Cerebral Artery Stroke

Sergio Paradiso, Beth M. Anderson, Laura L. Boles Ponto, Daniel Tranel, Robert G. Robinson
2011 Journal of Stroke & Cerebrovascular Diseases  
and Purpose-Stroke of the right MCA is common. Such strokes often have consequences for emotional experience, but these can be subtle. In such cases diagnosis is difficult because emotional awareness (limiting reporting of emotional changes) may be affected. The present study sought to clarify the mechanisms of altered emotion experience after right MCA stroke. It was predicted that after right MCA stroke the anterior cingulate cortex (ACC), a brain region concerned with emotional awareness,
more » ... ld show reduced neural activity. Methods-Brain activity during presentation of emotional stimuli was measured in six patients with stable stroke, and in 12 age and gender matched non-lesion comparisons using positron emission tomography and the [ 15 O]H 2 O autoradiographic method. Results-MCA stroke was associated with weaker pleasant experience and decreased activity ipsilaterally in the ACC. Other regions involved in emotional processing including thalamus, dorsal and medial prefrontal cortex showed reduced activity ipsilaterally. Dorsal and medial prefrontal cortex, association visual cortex and cerebellum showed reduced activity contralaterally. Experience from unpleasant stimuli was unaltered and was associated with decreased activity only in the left midbrain. Conclusions-Right MCA stroke may reduce experience of pleasant emotions by altering brain activity in limbic and paralimbic regions distant from the area of direct damage, in addition to changes due to direct tissue damage to insula and basal ganglia. The knowledge acquired in this study begins to explain the mechanisms underlying emotional changes following right MCA stroke. Recognizing these changes may improve diagnoses, management and rehabilitation of right MCA stroke victims.
doi:10.1016/j.jstrokecerebrovasdis.2009.11.005 pmid:20656512 pmcid:PMC3014997 fatcat:jm7djkg5a5erljdom4x3by5cte

A role for left temporal pole in the retrieval of words for unique entities

Thomas J. Grabowski, Hanna Damasio, Daniel Tranel, Laura L. Boles Ponto, Richard D. Hichwa, Antonio R. Damasio
2001 Human Brain Mapping  
Effect of task (naming unique entities vs. baseline tasks): L mesial frontal 6.21 Ϫ1 ϩ42 ϩ23 L inferior frontal gyrus 8.64 Ϫ37 ϩ22 ϩ1 L retrospenial region 7.65 ϩ4 Ϫ60 ϩ16 L collateral  ...  sulcus 6.73 Ϫ20 Ϫ27 Ϫ21 R cerebellum 5.61 ϩ11 Ϫ42 Ϫ20 L central cortex 6.14 Ϫ27 Ϫ4 ϩ34 L mesial frontal 4.98 Ϫ2 ϩ15 ϩ45 R parietal 4.94 Ϫ46 Ϫ73 ϩ29 B.  ... 
doi:10.1002/hbm.1033 pmid:11410949 fatcat:hnvoq4xbqbbadlbkqpqtz73ctq

Emotions in Unmedicated Patients With Schizophrenia During Evaluation With Positron Emission Tomography

Sergio Paradiso, Nancy C. Andreasen, Benedicto Crespo-Facorro, Daniel S. O'Leary, G. Leonard Watkins, Laura L. Boles Ponto, Richard D. Hichwa
2003 American Journal of Psychiatry  
Objective: Schizophrenia is currently conceptualized as a disease of functional neural connectivity, leading to symptoms that affect aspects of mental activity, including perception, attention, memory, and emotion. The neural substrates of its emotional components have not been extensively studied with functional neuroimaging. Previous neuroimaging studies have examined medicated patients with schizophrenia. The authors measured regional cerebral blood flow (rCBF) during performance of a task
more » ... at required unmedicated patients to recognize the emotional valence of visual images and to determine whether they were pleasant or unpleasant. Method: The authors examined rCBF in 17 healthy volunteers and 18 schizophrenia patients who had not received antipsychotic medications for at least 3 weeks during responses to pleasant and unpleasant visual stimuli. Areas of relative increases or decreases in rCBF were measured by using the [ 15 O]H 2 O method. Results: When patients consciously evaluated the unpleasant images, they did not activate the phylogenetically older feardanger recognition circuit (e.g., the amygdala) used by the healthy volunteers, although they correctly rated them as unpleasant. Likewise, the patients showed no activation in areas of the prefrontal cortex normally used to recognize the images as pleasant and were unable to recognize them as such. Areas of decreased CBF were widely distributed and comprised subcortical regions such as the thalamus and cerebellum. Conclusions: This failure of the neural systems used to support emotional attribution is consistent with pervasive problems in experiencing emotions by schizophrenia patients. The widely distributed nature of the abnormalities suggests the importance of subcortical nodes in overall dysfunctional connectivity.
doi:10.1176/appi.ajp.160.10.1775 pmid:14514490 fatcat:hoaxoxhw2nczjbykkvpixgporu

A role for left temporal pole in the retrieval of words for unique entities

Thomas J. Grabowski, Hanna Damasio, Daniel Tranel, Laura L. Boles Ponto, Richard D. Hichwa, Antonio R. Damasio
2001 Human Brain Mapping  
Effect of task (naming unique entities vs. baseline tasks): L mesial frontal 6.21 Ϫ1 ϩ42 ϩ23 L inferior frontal gyrus 8.64 Ϫ37 ϩ22 ϩ1 L retrospenial region 7.65 ϩ4 Ϫ60 ϩ16 L collateral  ...  sulcus 6.73 Ϫ20 Ϫ27 Ϫ21 R cerebellum 5.61 ϩ11 Ϫ42 Ϫ20 L central cortex 6.14 Ϫ27 Ϫ4 ϩ34 L mesial frontal 4.98 Ϫ2 ϩ15 ϩ45 R parietal 4.94 Ϫ46 Ϫ73 ϩ29 B.  ... 
doi:10.1002/hbm.1033.abs pmid:11410949 fatcat:cstr6v5t2bgvhiskjznbupx6gy

Spatial mapping of functional pelvic bone marrow using FLT PET

Sarah M. McGuire, Yusuf Menda, Laura L. Boles Ponto, Brandie Gross, Mindi TenNapel, Brian J. Smith, John E. Bayouth
2014 Journal of Applied Clinical Medical Physics  
The purpose of this study was to determine the ability of regions identified with bony landmarks on CT imaging to accurately represent active bone marrow when compared to FLT PET imaging. These surrogate regions could then be used to create a bone marrow sparing radiation therapy plan when FLT PET imaging is not available. Whole body (WB) FLT PET images were obtained of 18 subjects prior to chemoradiation therapy. The FLT image of each subject was registered to a CT image acquired for that
more » ... ct to obtain anatomic information of the pelvis. Seventeen regions were identified based on features of the pelvic bones, sacrum, and femoral heads. The probability of FLT uptake being located in each of 17 different CT-based regions of the bony pelvis was calculated using Tukey's multiple comparison test. Statistical analysis of FLT uptake in the pelvis indicated four distinct groups within the 17 regions that had similar levels of activity. Regions located in the central part of the pelvis, including the superior part of the sacrum, the inner halves of the iliac crests, and the L5 vertebral body, had greater FLT uptake than those in the peripheral regions (p-value < 0.05). We have developed a method to use CT-defined pelvic bone regions to represent FLT PET-identified functional bone marrow. Individual regions that have a statistically significant probability of containing functional bone marrow can be used as avoidance regions to reduce radiation dose to functional bone marrow in radiation therapy planning. However, because likely active bone marrow regions and pelvic targets typically overlap, patient-specific spatial detail may be advantageous in IMRT planning scenarios and may best be provided using FLT PET imaging.
doi:10.1120/jacmp.v15i4.4780 pmid:25207403 pmcid:PMC4161980 fatcat:5mxmtsmjoffc3a7g7w5yegljqu

Multimodality noninvasive imaging of gene transfer using the human sodium iodide symporter

Gang Niu, Andrew W Gaut, Laura L Boles Ponto, Richard D Hichwa, Mark T Madsen, Michael M Graham, Frederick E Domann
2004 Journal of Nuclear Medicine  
All cells were cultured in RPMI 1640 medium with Glutamax-I supplemented with 10% fetal bovine serum, 100 IU/mL penicillin, and 100 mg/L streptomycin (GIBCO) at 37°C, in a 95% air/5% CO 2 atmosphere.  ... 
pmid:15001685 fatcat:3q4djzxibvad7mlyy6op2s5e5e
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