James Blair

Choice selection and reward anticipation: An fMRI study

We examined neural activations during decision-making using fMRI paired with the wheel of fortune task, a newly developed two-choice decision-making task with probabilistic monetary gains. In particular, we assessed the impact of high-reward/risk events relative to low-reward/risk events on neural activations during choice selection and during reward anticipation. Seventeen healthy adults completed the study. We found, in line with predictions, that (i) the selection phase predominantly recruited regions involved in visuo-spatial attention (occipito-parietal pathway), conflict (anterior cingulate), manipulation of quantities (parietal cortex), and preparation for action (premotor area), whereas the anticipation phase prominently recruited regions engaged in reward processes (ventral striatum); and (ii) high-reward/risk conditions relative to low-reward/risk conditions were associated with a greater neural response in ventral striatum during selection, though not during anticipation. Following an a priori ROI analysis focused on orbitofrontal cortex, we observed orbitofrontal cortex activation (BA 11 and 47) during selection (particularly to high-risk/reward options), and to a more limited degree, during anticipation. These findings support the notion that (1) distinct, although overlapping, pathways subserve the processes of selection and anticipation in a two-choice task of probabilistic monetary reward; (2) taking a risk and awaiting the consequence of a risky decision seem to affect neural activity differently in selection and anticipation; and thus (3) common structures, including the ventral striatum, are modulated differently by risk/reward during selection and anticipation.

Neural dynamics for facial threat processing as revealed by gamma band synchronization using MEG

Facial threat conveys important information about imminent environmental danger. The rapid detection of this information is critical for survival and social interaction. However, due to technical and methodological difficulties, the spatiotemporal profile for facial threat processing is unknown. By utilizing magnetoencephalography (MEG), a brain-imaging technique with superb temporal resolution and fairly good spatial resolution, Synthetic Aperture Magnetometry (SAM), a recently developed source analysis technique, and a sliding window analysis, we identified the spatiotemporal development of facial threat processing in the gamma frequency band. We also tested the dual-route hypothesis by LeDoux who proposed, based on animal research, that there are two routes to the amygdala: a quick subcortical route and a slower and cortical route. Direct evidence with humans supporting this model has been lacking. Moreover, it has been unclear whether the subcortical route responds specifically to fearful expressions or to threatening expressions in general. We found early event-related synchronizations (ERS) in response to fearful faces in the hypothalamus/thalamus area (10-20 ms) and then the amygdala (20-30 ms). This was even earlier than the ERS response seen to fearful faces in visual cortex (40-50 ms). These data support LeDouxs suggestion of a quick, subcortical thamalo-amygdala route. Moreover, this route was specific for fear expressions; the ERS response in the amygdala to angry expressions had a late onset (150-160 ms). The ERS onset in prefrontal cortex followed that seen within the amygdala (around 160-210 ms). This is consistent with its role in higher-level emotional/cognitive processing.

Increased Amygdala Activity During Successful Memory Encoding in Adolescent Major Depressive Disorder: An fMRI Study

BACKGROUND Although major depressive disorder (MDD) represents one of the most serious psychiatric problems afflicting adolescents, efforts to understand the neural circuitry of adolescent MDD have lagged behind those of adult MDD. This study tests the hypothesis that adolescent MDD is associated with abnormal amygdala activity during evocative-face viewing. METHODS Using functional magnetic resonance imaging (fMRI), between-group differences among MDD (n = 10), anxious (n = 11), and non-psychiatric comparisons (n = 23) were examined during successful vs. unsuccessful face encoding, with encoding success measured post-scan. RESULTS Compared to healthy adolescents, MDD patients exhibited poorer memory for faces. fMRI analyses accounted for this performance difference through event-related methods. In an analysis comparing successful vs. unsuccessful face encoding, MDD patients exhibited greater left amygdala activation relative to healthy and anxious youth. CONCLUSIONS Given prior findings among adults, this study suggests that adolescent and adult MDD may involve similar underlying abnormalities in amygdala functioning.

Visual Awareness, Emotion, and Gamma Band Synchronization

What makes us become aware? A popular hypothesis is that if cortical neurons fire in synchrony at a certain frequency band (gamma), we become aware of what they are representing. We tested this hypothesis adopting brain-imaging techniques with good spatiotemporal resolution and frequency-specific information. Specifically, we examined the degree to which increases in event-related synchronization (ERS) in the gamma band were associated with awareness of a stimulus (its detectability) and/or the emotional content of the stimulus. We observed increases in gamma band ERS within prefrontal–anterior cingulate, visual, parietal, posterior cingulate, and superior temporal cortices to stimuli available to conscious awareness. However, we also observed increases in gamma band ERS within the amygdala, visual, prefrontal, parietal, and posterior cingulate cortices to emotional relative to neutral stimuli, irrespective of their availability to conscious access. This suggests that increased gamma band ERS is related to, but not sufficient for, consciousness.

Improvement in cerebral function with treatment of posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) are signature illnesses of the Iraq and Afghanistan wars, but current diagnostic and therapeutic measures for these conditions are suboptimal. In our study, functional magnetic resonance imaging (fMRI) is used to try to differentiate military service members with: PTSD and mTBI, PTSD alone, mTBI alone, and neither PTSD nor mTBI. Those with PTSD are then randomized to virtual reality exposure therapy or imaginal exposure. fMRI is repeated after treatment and along with the Clinician‐Administered PTSD Scale (CAPS) and Clinical Global Impression (CGI) scores to compare with baseline. Twenty subjects have completed baseline fMRI scans, including four controls and one mTBI only; of 15 treated for PTSD, eight completed posttreatment scans. Most subjects have been male (93%) and Caucasian (83%), with a mean age of 34. Significant improvements are evident on fMRI scans, and corroborated by CGI scores, but CAPS scores improvements are modest. In conclusion, CGI scores and fMRI scans indicate significant improvement in PTSD in both treatment arms, though CAPS score improvements are less robust.

Spinal Column Injuries Among Americans in the Global War on Terrorism

BACKGROUND While combat spinal injuries have been documented since the fourth century BC, a comprehensive analysis of such injuries has not been performed for any American military conflict. Recent literature has suggested that spinal injuries account for substantial disability in wounded service members. METHODS The Joint Theater Trauma Registry was queried to identify all American military personnel who sustained injuries to the back, spinal column, and/or spinal cord in Iraq or Afghanistan from October 2001 to December 2009. Spinal injuries were categorized according to anatomic location, neurological involvement, mechanism of injury, and concomitant wounds. RESULTS Of 10,979 evacuated combat casualties, 598 (5.45%) sustained 2101 spinal injuries. Explosions accounted for 56% of spinal injuries, motor vehicle collisions for 29%, and gunshots for 15%. Ninety-two percent of all injuries were fractures, with transverse process, compression, and burst fractures the most common. Spinal cord injuries were present in 17% (104) of the 598 patients. Concomitant injuries frequently occurred in the abdomen, chest, head, and face. CONCLUSIONS The incidence of spine trauma sustained by military personnel in Iraq and Afghanistan is higher than that reported for previous conflicts, and the nature of these injuries may be similar to those in severely injured civilians. Further research into optimal management and rehabilitation is critical for military service members and severely injured civilians with spine trauma.

Return to Running and Sports Participation After Limb Salvage

BACKGROUND The ability to return to running and sports participation after lower extremity limb salvage has not been well documented previously. Although the ability to ambulate without pain or assistive devices is generally a criteria for a good limb salvage outcome, many patients at our institution have expressed a desire to return to a more athletic lifestyle to include running and sports participation. The purpose of this study was to investigate the types of athletic endeavors our high-energy lower extremity trauma patients were able to pursue after limb salvage. METHODS We retrospectively analyzed lower extremity limb salvage patients who were at least 12 weeks status after external fixation removal and participated in our limb salvage return-to-running clinical pathway. Patients were rehabilitated to their highest functional level through a sports medicine-based approach. A custom energy-storing ankle-foot orthosis was implemented to help augment plantarflexion strength in conjunction with running gait retraining. RESULTS The first 10 patients to complete the clinical pathway were identified. All patients were treated at the same institution by the same orthopedic surgeon and physical therapist. Eight patients have returned to running, and 10 patients have returned to weight-lifting. Seven patients have returned to cycling, three have returned to golf, three to basketball, and two to softball. Two patients have completed a mini-triathlon. CONCLUSION Aggressive rehabilitation, an energy-storing ankle-foot orthosis, and running gait retraining can restore an active recreational lifestyle to patients who have undergone lower extremity limb salvage.

Military penetrating spine injuries compared with blunt

BACKGROUND CONTEXT The nature of blunt and penetrating injuries to the spine and spinal column in a military combat setting has been poorly documented in the literature. To date, no study has attempted to characterize and compare blunt and penetrating spine injuries sustained by American servicemembers. PURPOSE The purpose of this study was to compare the military penetrating spine injuries with blunt spine injuries in the current military conflicts. STUDY DESIGN/SETTING Retrospective study. PATIENT SAMPLE All American military servicemembers who have been injured while deployed in Iraq (Operation Iraqi Freedom) and Afghanistan (Operation Enduring Freedom) whose medical data have been entered into the Joint Theater Trauma Registry (JTTR). METHODS The JTTR was queried for all American servicemembers sustaining an injury to the spinal column or spinal cord while deployed in Iraq or Afghanistan. These data were manually reviewed for relevant information regarding demographics, mechanism of injury, surgical intervention, and neurologic injury. RESULTS A total of 598 servicemembers sustained injuries to the spine or spinal cord. Isolated blunt injuries were recorded in 396 (66%) servicemembers and 165 (28%) sustained isolating penetrating injuries. Thirty servicemembers (5%) sustained combined blunt and penetrating injuries to the spine. The most commonly documented injuries were transverse process fractures, compression fractures, and burst fractures in the blunt-injured servicemembers versus transverse process fractures, lamina fractures, and spinous process fractures in those injured with a penetrating injury. One hundred four (17%) servicemembers sustained spinal cord injuries, comprising 10% of blunt injuries and 38% of penetrating injuries (p<.0001). Twenty-eight percent (28%) of blunt-injured servicemembers underwent a surgical procedure compared with 41% of those injured by penetrating mechanisms (p=.4). Sixty percent (n=12/20) of blunt-injured servicemembers experienced a neurologic improvement after surgical intervention at follow-up compared with 43% of servicemembers (n=10/23) who underwent a surgical intervention after a penetrating trauma (p=.28). Explosions accounted for 58% of blunt injuries and 47% of penetrating injuries, whereas motor vehicle collisions accounted for 40% of blunt injuries and 2% of penetrating injuries. Concomitant injuries to the abdomen, chest, and head were common in both groups. CONCLUSIONS Blunt and penetrating injuries to the spinal column and spinal cord occur frequently in the current conflicts in Iraq and Afghanistan. Penetrating injuries result in significantly higher rates of spinal cord injury and trend toward increased rates of operative interventions and decreased neurologic improvement at follow-up.

Are spine injuries sustained in battle truly different

BACKGROUND CONTEXT The severity and prognosis of combat-related injuries to the spine and spine injuries sustained unrelated to direct combat have not been previously compared. Differences may have implications on tactics, treatment strategies, and directions for future research. PURPOSE Compare the severity and prognosis of battle and nonbattle injuries to the spine. STUDY DESIGN Retrospective study. PATIENT SAMPLE American military personnel who were injured in a combat zone and whose medical data were abstracted in the Joint Theater Trauma Registry (JTTR). METHODS The JTTR was queried using International Statistical Classification of Diseases, Ninth Revision codes to identify all individuals who sustained battle and nonbattle injuries to the neck, back, spinal column, or spinal cord in Operation Iraqi Freedom or Operation Enduring Freedom from October 2001 to December 2009. Medical records of all identified servicemembers were individually reviewed. Demographic information, including sex, age, military rank, date of injury, and final disposition, was obtained for all patients. Spinal injuries were categorized according to anatomic location, associated neurologic involvement, precipitating mechanism of injury (MOI), and concomitant wounds. These data points were compared for the groups battle spine injuries (BSIs) and nonbattle spine injuries (NBSIs). RESULTS Five hundred two servicemembers sustained a total of 1,834 battle injuries to the spinal column, including 1,687 fractures (92%), compared with 92 servicemembers sustaining 267 nonbattle spinal column injuries, with 241 (90%) fractures. Ninety-one BSI servicemembers (18% of patients) sustained spinal cord injuries (SCIs) with 41 (45%) complete SCIs, compared with 13 (14% of patients) nonbattle SCIs with six (46.2%) complete injuries (p=.92). The reported MOI for 335 BSI servicemembers (66.7%) was an explosion compared with one NBSI explosive injury. Eighty-four patients (17%) sustained gunshot wounds (GSWs) in battle compared with five (5.2%) nonbattle GSWs. Fifteen patients (3.0%) sustained a battle-related fall compared with 29 (30%) nonbattle-related falls. Battle spine injury servicemembers underwent significantly higher rates of surgical interventions (p<.0001), were injured by high-energy injury mechanisms at a significantly greater rate (p<.0001), and demonstrated a trend toward lower neurologic recovery rates after SCI (p=.16). CONCLUSIONS Battle spine injury and NBSI are separate entities that may ultimately have disparate long-term prognoses. Nonbattle spine injury patients, although having similar MOIs compared with civilian spinal trauma, maintain a different patient demographic. Further research must be directed at accurately quantifying the long-term disabilities of all spine injuries sustained in a combat theater, whether they are the result of battle or not.

Quantification of Femoral Neck Exposure Through a Minimally Invasive Smith-Petersen Approach

Objectives: To quantify the area of osseous exposure and identify six anatomic landmarks using a direct anterior approach to the hip. Methods: Ten fresh-frozen hemipelves were dissected using a minimally invasive Smith-Petersen approach. Upon completion of the exposure, a calibrated digital image was taken from the surgeons perspective. Identification of six osseous landmarks (anterior-superior acetabulum, anterior-inferior acetabulum, greater trochanter, lesser trochanter, anterior inferior iliac spine, and vastus ridge) was attempted either by direct visualization or palpation with a tonsil clamp. These landmarks exceed the border for any intracapsular hip fracture. The digital images were then analyzed using a computer software program, ImageJ (National Institutes of Health, Bethesda, MD), to calculate the square area of proximal femur exposed. Results: The average square area of proximal femur exposed was 20.31 cm2 (standard deviation: 3.09, range: 15.16-24.18). The area exposed correlated with the original height of the cadaver (r = 0.69, P < 0.05). With the numbers available, there was no correlation between exposure and weight (P = 0.71) or body mass index (P = 0.87). In all 10 cadaver specimens, the 6 osseous landmarks were easily identified, 5 by direct visualization and 1 by palpation (lesser trochanter, deep portion) because of incomplete visualization. Conclusions: The minimally invasive Smith-Petersen approach to the hip allows for a wide exposure of the femoral neck averaging 20.31 cm2 and identification of six bony critical landmarks of the hip. It may be used for open reduction of subcapital, mid-cervical, and basicervical femoral neck fractures.