Thomas W Freeman

University of Texas at Dallas, Dallas, TX, United States

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Publications (21)64.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Threatening stimuli have been found to modulate visual processes related to perception and attention. The present functional magnetic resonance imaging (fMRI) study investigated whether threat modulates visual object recognition of man-made and naturally occurring categories of stimuli. Compared with nonthreatening pictures, threatening pictures of real items elicited larger fMRI BOLD signal changes in medial visual cortices extending inferiorly into the temporo-occipital (TO) "what" pathways. This region elicited greater signal changes for threatening items compared to nonthreatening from both the natural-occurring and man-made stimulus supraordinate categories, demonstrating a featural component to these visual processing areas. Two additional loci of signal changes within more lateral inferior TO areas (bilateral BA18 and 19 as well as the right ventral temporal lobe) were detected for a category-feature interaction, with stronger responses to man-made (category) threatening (feature) stimuli than to natural threats. The findings are discussed in terms of visual recognition of processing efficiently or rapidly groups of items that confer an advantage for survival. Hum Brain Mapp, 2012. © 2012 Wiley Periodicals, Inc.
    Human Brain Mapping 03/2012; · 6.88 Impact Factor
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    ABSTRACT: Using the event-related potential P3a component as a marker, the authors tested the efficacy of repetitive transcranial magnetic stimulation (rTMS) for reducing hyperarousability to specific threat stimuli in one Vietnam veteran with chronic posttraumatic stress disorder (PTSD), who exhibited an exaggerated P3a response to combat-related pictures. Twenty minutes of 1-Hz rTMS to the right prefrontal area effected a reduction in the P3a amplitude, whereas similar rTMS to the left prefrontal area did not. In addition to providing evidence for the effectiveness of right frontal rTMS for an exaggerated response to trauma-related stimuli, this study provides electrophysiological corroboration of subjective reports of PTSD symptoms.
    The Journal of neuropsychiatry and clinical neurosciences 01/2011; 23(1):40-7. · 2.34 Impact Factor
  • Thomas W Freeman, John Hart, Tim Kimbrell, Elliott D Ross
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    ABSTRACT: Posttraumatic stress disorder (PTSD) is one of the few psychiatric conditions in which a subjective decrease in emotional range serves as a diagnostic criterion. In order to investigate whether veterans with chronic PTSD also experienced objective limitations in emotional perception, the authors administered the Aprosodia Battery to a group of 11 veterans with chronic PTSD, nine subjects with right hemisphere damage, seven subjects with left hemisphere damage, and 12 comparison subjects. The patients with PTSD displayed significant deficiencies in the comprehension and discriminative components of affective speech, similar in severity and performance profile on the Aprosodia Battery to the individuals with focal right hemisphere damage due to ischemic infarction.
    The Journal of neuropsychiatry and clinical neurosciences 02/2009; 21(1):52-8. · 2.34 Impact Factor
  • Thomas Freeman, Melissa Powell, Tim Kimbrell
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    ABSTRACT: Veteran subjects with chronic, combat-related posttraumatic stress disorder (PTSD) are frequently used as research subjects in the study of PTSD. However, questions have consistently been raised regarding PTSD symptom exaggeration in veteran populations due to the relationship between PTSD symptoms and disability payments within the Veterans Affairs (VA) system. We used a variety of standardized forensic instruments frequently utilized in measuring symptom exaggeration - including the MMPI-2, the Structured Interview for Reported Symptoms (SIRS), the Structured Inventory of Malingered Symptomatology (SIMS), and the Miller Forensic Assessment Test (MFAST) - to examine symptom report in a group of veterans presenting for treatment at a VA residential PTSD treatment program. The majority of Vietnam veteran subjects in our study (53%) exhibited clear symptom exaggeration by SIRS criteria. Within the entire subject group, total SIRS scores correlated significantly with reported PTSD symptom severity as measured by the Clinician Administered PTSD Scale (CAPS).
    Psychiatry Research 05/2008; 158(3):374-80. · 2.68 Impact Factor
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    ABSTRACT: The authors aim to delineate cognitive dysfunction associated with posttraumatic stress disorder (PTSD) by evaluating a well-defined cohort of former World War II prisoners of war (POWs) with documented trauma and minimal comorbidities. The authors studied a cross-sectional assessment of neuropsychological performance in former POWs with PTSD, PTSD with other psychiatric comorbidities, and those with no PTSD or psychiatric diagnoses. Participants who developed PTSD had average IQ, while those who did not develop PTSD after similar traumatic experiences had higher IQs than average (approximately 116). Those with PTSD performed significantly less well in tests of selective frontal lobe functions and psychomotor speed. In addition, PTSD patients with co-occurring psychiatric conditions experienced impairment in recognition memory for faces. Higher IQ appears to protect individuals who undergo a traumatic experience from developing long-term PTSD, while cognitive dysfunctions appear to develop with or subsequent to PTSD. These distinctions were supported by the negative and positive correlations of these cognitive dysfunctions with quantitative markers of trauma, respectively. There is a suggestion that some cognitive decrements occur in PTSD patients only when they have comorbid psychiatric diagnoses.
    The Journal of neuropsychiatry and clinical neurosciences 02/2008; 20(3):309-16. · 2.34 Impact Factor
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    ABSTRACT: The neural interface between sensory perception and memory is a central issue in neuroscience, particularly initial memory organization following perceptual analyses. We used functional magnetic resonance imaging to identify anatomic regions extracting initial auditory semantic memory information related to environmental sounds. Two distinct anatomic foci were detected in the right superior temporal gyrus when subjects identified sounds representing either animals or threatening items. Threatening animal stimuli elicited signal changes in both foci, suggesting a distributed neural representation. Our results demonstrate both category- and feature-specific responses to nonverbal sounds in early stages of extracting semantic memory information from these sounds. This organization allows for these category-feature detection nodes to extract early, semantic memory information for efficient processing of transient sound stimuli. Neural regions selective for threatening sounds are similar to those of nonhuman primates, demonstrating semantic memory organization for basic biological/survival primitives are present across species.
    Journal of Cognitive Neuroscience 12/2006; 18(11):1877-88. · 4.49 Impact Factor
  • V Roca, J Hart, T Kimbrell, T Freeman
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    ABSTRACT: Twenty-seven veteran subjects with chronic posttraumatic stress disorder (PTSD) were evaluated for dissociative disorders. Ten subjects met criteria for one or more dissociative disorders, and 17 subjects did not meet dissociative disorder criteria. Neurocognitive profiles of the two groups differed in several areas, with veterans meeting diagnostic criteria for both PTSD and a dissociative disorder and demonstrating considerably greater deficits in attention, autobiographical memory, and verbal memory than PTSD subjects without comorbid dissociative disorder diagnosis.
    Journal of Neuropsychiatry 02/2006; 18(2):226-30. · 2.40 Impact Factor
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    ABSTRACT: In this study, single voxel proton magnetic resonance spectroscopic imaging ((1)H-MRS) and volumetric analysis of hippocampal magnetic resonance imaging (MRI) images were used to determine if any differences in hippocampal biochemistry or volume were present between former prisoners of war (POWs) with and without posttraumatic stress disorder (PTSD) and control subjects matched for age and education. This study did not find lower hippocampal concentrations of N-acetylaspartate (NAA), smaller hippocampal volumes, or more impaired memory function in older veterans with PTSD compared with a group matched for traumatic experience or a nontraumatized control group.
    Psychiatry Research 02/2006; 146(1):59-64. · 2.68 Impact Factor
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    ABSTRACT: Veterans diagnosed with combat-related posttraumatic stress disorder (PTSD) and comparison subjects underwent single voxel proton magnetic resonance spectroscopy (1H-MRS) of the medial temporal lobe (MTL). PTSD subjects were divided into combat and non-combat groups based on military records. Combat PTSD subjects did not have lower MTL levels of N-acetylaspartate compared with non-combat PTSD subjects.
    Psychiatry Research 11/2005; 140(1):91-4. · 2.68 Impact Factor
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    ABSTRACT: To determine the relationship between weight loss suffered by former prisoners of war during captivity during World War II and the Korean Conflict and current posttraumatic stress disorder (PTSD) symptoms, the Clinician-Administered PTSD Symptom Scale, a lifetime stressor checklist, and the Structured Clinical Interview for DSM-IV were administered to 102 former prisoners of war. Preconfinement and postconfinement weights and length of confinement were obtained from military medical records. Percentage of body weight lost during captivity was significantly higher in those subjects with PTSD and correlated with current PTSD symptom severity. Length of confinement was not associated with current PTSD symptoms.
    Journal of Nervous & Mental Disease 05/2005; 193(4):278-80. · 1.84 Impact Factor
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    ABSTRACT: Previous studies have reported associations between apolipoprotein E (APOE) genotype, cognitive function, and psychopathology in psychiatric populations. The authors investigated the associations between APOE allele status, memory function, and posttraumatic stress disorder (PTSD) symptom severity in PTSD subjects. Presence of the APOE 2 allele was associated with significantly worse reexperiencing symptoms and impaired memory function in this population.
    Journal of Neuropsychiatry 02/2005; 17(4):541-3. · 2.40 Impact Factor
  • Thomas Freeman, Tim Kimbrell
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    ABSTRACT: To examine the relationship of alcohol craving to symptoms of posttraumatic stress disorder (PTSD), 129 male veterans with chronic PTSD were asked to complete the Obsessive Compulsive Drinking Scale (OCDS), the Mississippi Scale for combat-related PTSD symptoms, and other instruments to assess general psychopathology and lifetime alcohol and substance use. No correlations were found between current PTSD symptoms and alcohol craving, although significant correlations were found between the OCDS and measures of lifetime alcohol and substance use.
    Journal of Nervous & Mental Disease 06/2004; 192(5):389-90. · 1.84 Impact Factor
  • Source
    T Kimbrell, M Myers, T Freeman
    The British Journal of Psychiatry 10/2003; 183:263. · 6.61 Impact Factor
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    Tim A Kimbrell, Thomas W Freeman
    Psychiatric Services 07/2003; 54(6):910-1. · 2.01 Impact Factor
  • Thomas W Freeman, Vincent Roca, Tim Kimbrell
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    ABSTRACT: An important risk factor for suicide is psychiatric illness, but only a limited amount of work has been directed at assessing the use of firearms and other weapons by select psychiatric populations at high risk for violent acts. Patients with combat-related posttraumatic stress disorder (PTSD), patients with schizophrenia, and patients undergoing rehabilitation for substance abuse were asked to complete a weapons-use survey and measures of psychopathology. The PTSD patients surveyed related owning more than four times as many firearms as other subjects and reported significantly higher levels of potentially dangerous firearm-related behaviors than the other psychiatric subjects surveyed. High levels of aggression, impulsive and dangerous weapon use, and ready weapon availability may be significant factors in gun-related violence in the PTSD patient population. Additional prospective research is needed to determine whether gun ownership or certain types of weapon use in this population is associated with future acts of violence.
    Southern Medical Journal 04/2003; 96(3):240-3. · 0.92 Impact Factor
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    ABSTRACT: Proton magnetic resonance spectroscopy was used to compare medial temporal lobe (MTL) concentrations of N-acetylaspartate and choline between former prisoners of war (POWs) with and without posttraumatic stress disorder (PTSD). MTL N-acetylaspartate and reexperiencing symptoms correlated strongly in the POW subjects with PTSD, suggesting a relationship between reexperiencing symptoms and the integrity of MTL structures.
    Journal of Neuropsychiatry 02/2003; 15(3):367-70. · 2.40 Impact Factor
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    ABSTRACT: Bartzokis, G Freeman, T Roca, V Kimbrell, T Brown, SJ Lu, PH Turner, J Mintz, J Saunders, S
    Biological Psychiatry 01/2003; 53:135S-135S. · 9.25 Impact Factor
  • Vincent Roca, Thomas W Freeman
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    ABSTRACT: Psychosensory symptoms have relevance to the study of chronic posttraumatic stress disorder (PTSD), given that their presence is associated with limbic system dysfunction and that several features of chronic PTSD suggest that it, too, may be associated with limbic dysfunction. The Iowa Interview for Partial Seizure-like Symptoms (IIPSS), a measure of psychosensory symptoms, was administered to a PTSD group and a comparison group. The PTSD group generated significantly higher IIPSS scores than did the other group. Within the PTSD group, higher IIPSS scores were associated with significantly more severe PTSD symptoms, dissociative symptoms, aggression, and overall psychopathology.
    Journal of Neuropsychiatry 02/2002; 14(2):185-9. · 2.40 Impact Factor
  • G. Bartzokis, T. Freeman, V. Roca
    European Neuropsychopharmacology - EUR NEUROPSYCHOPHARMACOL. 01/2001; 11.
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    ABSTRACT: Recent findings using volumetric MRI techniques have revealed that patients with combat-related and noncombat-related posttraumatic stress disorder (PTSD) have reductions in right hippocampal volume. Twenty-one veterans with PTSD and eight age-matched control veterans were studied using proton magnetic resonance spectroscopy to test the hypothesis that the N-acetyl-L-aspartic acid/creatine (NAA/Cr) ratio would be decreased in the right medial temporal lobe structures of patients with PTSD compared to controls. Patients with PTSD displayed significantly lower NAA/Cr ratio for the right medial temporal lobe relative to the left (P < or = 0.011). Patients with PTSD also had lower NAA/Cr in right medial temporal lobe (P < or = 0.013) and lower choline/Cr in left medial temporal lobe (P < or = 0.030) compared to control subjects. Because NAA is regarded as an indicator of neuronal density, this finding suggests that the neuronal density of right-sided medial temporal structures in patients with combat-related PTSD may be decreased.
    Magnetic Resonance in Medicine 07/1998; 40(1):66-71. · 3.27 Impact Factor

Publication Stats

290 Citations
64.30 Total Impact Points

Institutions

  • 2008–2012
    • University of Texas at Dallas
      • Center for BrainHealth
      Dallas, TX, United States
  • 2006–2012
    • Johns Hopkins Medicine
      Baltimore, Maryland, United States
  • 2004–2009
    • Central Arkansas Veterans Healthcare System
      Washington, Washington, D.C., United States
  • 2002–2008
    • U.S. Department of Veterans Affairs
      • Mental Health Services
      Washington, D. C., DC, United States
  • 1998–2003
    • University of Arkansas at Little Rock
      Little Rock, Arkansas, United States