Biomedical subjects

Wendy Snyder

Publications and source records attributed to Wendy Snyder.

3 recordsLinked to original sources

PubMed2007

Hemodynamic responses in neural circuitries for detection of visual target and novelty: An event-related fMRI study.

The oddball paradigm examines attentional processes by establishing neural substrates for target detection and novelty. Event-related functional imaging enables characterization of hemodynamic changes associated with these processes. We studied 36 healthy participants (17 men) applying a visual oddball event-related design at 4 Tesla, and performed an unbiased determination of the hemodynamic response function (HRF). Targets were associated with bilateral, albeit leftward predominant changes in frontal-parietal temporal and occipital cortices, and limbic and basal ganglia regions. Activation to novelty was more posteriorly distributed, and frontal activation occurred only on the right, while robust activation was seen in occipital regions bilaterally. Overlapping regions were left thalamus, caudate and cuneus and right parietal precuneus. While robust HRFs characterized most regions, target detection was associated with a negative HRF in the right parietal precuneus and a biphasic HRF in thalamus, basal ganglia, and all occipital regions. Both height of the HRF and longer time to peak in the right cingulate were associated with slower response time. Sex differences were observed, with higher HRF peaks for novelty in men in right occipital regions, and longer time to peak in the left hemisphere. Age was associated with reduced peak HRF in left frontal region. Thus, indices of the HRF can be used to better understand the relationship between hemodynamic changes and performance and can be sensitive to individual differences.

Adolescent↗

PubMed2006

Transoral robotic surgery (TORS) for base of tongue neoplasms.

OBJECTIVE: To develop a minimally invasive surgical technique for the treatment of base of tongue neoplasms using the optical and technical advantages of robotic surgical instrumentation. STUDY DESIGN: Ten experimental procedures including tongue base exposure and dissections were performed on three cadavers and two mongrel dogs. Transoral robotic surgery (TORS) was then performed on three human patients with tongue base cancers in a prospective human trial. METHODS: Using the da Vinci Surgical Robot (Intuitive Surgical, Inc., Sunnyvale, CA), we performed a total of 10 base of tongue resections on edentulous and dentate cadavers as well as live mongrel dogs. In the cadaver models, exposure was evaluated using three different retractors, the Dingman, Crowe Davis, and FK retractors. The three human patients underwent TORS surgery of their tongue base cancers under an institutional review board approved prospective clinical trial. The ability to identify and preserve or resect key anatomic structures such as the glossopharyngeal, hypoglossal, and lingual nerves as well as techniques for identifying the lingual artery and achieving hemostasis were developed. RESULTS: The da Vinci Surgical Robot provided excellent visualization and enabled removal of the posterior one third to one half of the oral tongue in cadavers, dogs, and human patients. Among the three retractors evaluated, the FK retractor offered the greatest versatility and overall exposure for robotic instrument maneuverability. Complete resection to negative surgical margins with excellent hemostasis and no complications was achieved in the live patient surgeries. CONCLUSIONS: TORS provided excellent three-dimensional visualization and instrument access that allowed successful surgical resections from cadaver models to human patients. TORS is a novel and minimally invasive approach to tongue neoplasms that has significant advantages over classic open surgery or endoscopic transoral laser surgery.

Animals↗

PubMed2003

Pre-migration trauma and HIV-risk behavior.

This study examined the relationship between pre-migration trauma and HIV-risk behavior in refugees from sub-Saharan Africa. The sample comprised 122 persons who had emigrated from sub-Saharan Africa and were currently residing in Sweden. Qualitative methods including individual interviews, focus groups, and interviews with key informants addressed questions regarding trauma experience and HIV-risk behavior. A history of pre-migration trauma was found to be associated with HIV-risk behavior. According to the participants, symptoms associated with post-traumatic stress disorder, depression, adjustment disorder, and substance use mediated the relationship between pre-migration trauma and sexual risk behavior. In contrast, a minority of the participants who reported pre-migration trauma but not psychological sequelae, or experienced post-traumatic growth, reported safer sexual practices. It appears that for some individuals, pre-migration trauma resulted in psychiatric sequelae, which may increase an individual's risk to be infected with HIV. Interventions targeted at individuals at increased risk (i.e. pre-migration trauma with unresolved psychiatric symptomatology) may facilitate the prevention of HIV and other sexually transmitted diseases in this population. Integration of multiple psychosocial and health issues is recommended for comprehensive treatment and prevention programs.

Adult↗