Sisyphus

 ... says it all, eh?

Jeff Radel, Ph.D.

Ph.D. `87; Dalhousie University, Halifax, Nova Scotia, Canada
M.A. `82; Dalhousie University, Halifax, Nova Scotia, Canada
B.A. '79; Oberlin College, Oberlin, Ohio, USA

Associate Professor, KU Medical Center
Dept. Occupational Therapy Education, School of Health Professions
Dept. Ophthalmology, School of Medicine
Dept. Molecular and Integrative Physiology, School of Medicine
Kansas Intellectual and Developmental Disabilities Research Center

Jeff Radel, PhD

Research Interests:

My research efforts address neural plasticity and function by investigating how anatomic relations and functional capacities of the visual system are altered after perturbations during development or through disease. Determining how neural information from multiple sources is integrated, how functional behaviors are influenced by that integration pattern, and how neural processing may be enhanced are factors fundamental to understanding the process of neural development, and for developing useful therapeutic interventions. A wide range of techniques are used to address these issues, including microsurgery and transplantation of neural tissue, a variety of histological procedures at the light microscopic and ultrastructural levels, behavioral and electrophysiological assessments of function, and systems analysis methodology.

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Brain injuries and recovery in youth and adolescent sports:

Brain injuries sustained during sports have become a focus of media attention. Much of that attention has been directed to the long-term consequences of repeated brain injuries among retired professional athletes, and an apparent correlation with neuropathology.  Other media reports have centered on devastating brain injuries experienced by younger athletes and the implications for permanent disability or death. Addressing “sport-related concussions” effectively clearly will require many factors to be considered, including the athlete’s age, sex, and state of brain development, the nature of the injury event, and the athlete’s history of prior brain injuries. The complexity of the interrelation among these factors also suggests that any single solution (e.g., build a better helmet) may be too simplistic of a solution.

 

I regularly speak with different audiences (players, parents, coaches, officials, teachers, and therapists) involved with youth and adolescent sports in the Kansas City area, to provide evidence-based programs about the nature of concussions in sports and current research about this topic. These educational programs increase awareness of this topic by providing a deeper understanding of the issues and a broader view of who may experience a concussion (which is anyone – male or female – participating in a sport where a blow to the head is possible). Recognizing the signs and symptoms of concussion and reconsidering accepted sports practices are steps that can be taken in youth and adolescent sports to reduce the number and severity of concussion. This knowledge also will help to identify post-concussion problems and support the injured player to return more quickly to normal activities.

 

These public education programs are intended to promote adoption of evidence-based coaching and clinical practices in our region. They also provide opportunities to recruit participants in a series of collaborative research activities among KU Medical Center physicians and investigators, schools and coaches, and healthcare businesses in the Kansas City area. This research coordinates efforts examining factors contributing to sport-related brain injuries and recovery in adolescents, to evaluating existing and emerging technologies for diagnosing concussions, and to considering the potential of prior injuries and ancillary activities in predisposing these young athletes to brain injury.  Outcome data will lead to a robust synthesis of knowledge having practical applications, guiding clinical practice, and supporting future education of coaches, parents, students, and healthcare professionals.

 

Our research efforts remain preliminary, but you are welcome to review the handouts from several recent education programs, presented to the  Youth Lacrosse coaches in Kansas City (Spring 2012), and to coaches from the Blue Valley Youth Football program (Summer 2012)

A related project explores the role of anomalous visual input on static balance. Oculomotor control deficits (e.g., vergence, tracking, etc.) have been reported in patients with persistent post-concussion symptoms. We are using the Sway-Balance iOS app (Capacity Sports, Inc.) and video headgear (Wrap 920; Vuzix, Inc.) to evaluate postural stability when normal vision is present, absent (occluded), or out of register with somatosensory and vestibular sensory inputs. (see examples of the video stimuli and preliminary data here).


Pupillary dynamics and diabetic autonomic neuropathy:

Impairment of cardiac function due to alterations in autonomic control of the heart, and a correlated increased mortality risk, both are serious health concerns for people with diabetes. The heart and the pupil are regulated by the autonomic nervous system, and generalized impairment of autonomic activity could lead to altered function in each system. This ongoing study assesses pupil dynamics of people with Type 2 diabetes, in both the resting and the light-activated states, to assess integrity of the sympathetic and parasympathetic divisions of the autonomic nervous system. These findings will be compared with cardiac data obtained from the same individuals, to determine if correlations exist.

Images, etc.: I've posted some preliminary related to the Pupil dynamics and diabetic autonomic neuropathy project.


DHA and the developing visual system:

A persistent research interest has been examining the influence of dietary docosahexanenoic acid (DHA) on neural development and function - particularly visual functions expressed at maturity. DHA is a long-chain (22:6n-3) fatty acid recognized as being essential for normal neural development. The demand for DHA is high during periods of rapid neural development; the primary source of DHA for mammals prenatally is the maternal blood supply, and the mother's breast milk after birth. Only recently, however, has DHA been included in commercial baby formulae. Moreover, low levels of DHA have been linked to both subtle and overt cognitive and behavioral deficits in children.

In these experiments, dietary levels of alpha-linolenic acid (the essential fatty acid precursor of DHA) are manipulated systematically during gestation and early development in rats. We then evaluate the influence of brain DHA levels on sensory processing in the adult central nervous system after the rats mature. Graded series of visual and auditory stimuli are used to evoke central neural responses 50 - 60 days after birth, and both naturally-expressed and drug-induced behaviors are investigated. Lipid composition of the brains of these mature rats is assayed and correlated with diet-related changes in evoked responses and behaviors. Although all diet conditions yield steady increases in brain levels of DHA, rats fed a diet deficient in alpha-linolenic acid consistently possess 20-30% less DHA than age-matched controls or animals fed a diet supplemented with DHA. Low brain DHA levels correlate with increased neural activity of central brain regions elicited by sensory stimulation, and with alterations in behavior. Supplementing the deficient diet with DHA at weaning, however, reverses the increased neural activity elicited by visual - but not auditory - stimuli. Similarly, some but not all behavioral alterations are reversed after supplementation.

Our data suggests that this increased activity in DHA-deficient rats may be due to dis-inhibition of cortical activity elicited by sensory stimulation. With single-point binding using radioligand at the KD, we've documented a 30% reduction in GABA-A receptor binding in the occipital cortex of DHA-deficient adult rats. Ongoing experiments will address the source of this reduction in GABA-A receptor binding through saturation analyses.

Images, etc.: I've posted some images related to the DHA & development projects.

Related publications:


DHA and retinal pathology:

The photoreceptors of the retina possess the highest concentrations of DHA in the mammalian nervous system. This makes the photoreceptors vulnerable to damage through oxidative stress _ but may mean that increasing levels of DHA systemically may act to buffer the effects of free radical damage. We have evaluated the influence of dietary fatty acids on severity of oxygen-induced retinopathy in newborn rats (an animal model of retinopathy of maturity in humans). This work suggests dietary fatty acids alone have little effect on oxygen-related vascular pathology in the retina, but only oxygen-treated rats who also are fed a diet high in DHA possess normal retinal concentrations of DHA. Moreover, low levels of DHA in combination with increased dietary iron leads to severe vascular pathology in oxygen-treated rats. The combination of these preliminary findings suggests a neutral role for DHA supplementation related to retinal vascular pathology in low birth weight human infants who require oxygen supplementation, but suggest a beneficial role for maintaining normal levels of retinal DHA - and thus better visual acuity for those infants who do not progress to end stage ROP.

Images, etc.: I've posted some images related to the DHA & retinal pathology projects.

Related publications:


Eye movements, reading, and the aging brain:

A second research interest is study of factors influencing control of eye movements in humans, particularly those made during daily life tasks (such as reading). A rich experimental literature addresses the physiological aspects of oculomotor control, and there is a similarly-rich literature on cognitive changes associated with aging. Reading is a highly complex activity, which requires precise integration of sensory, cognitive, and motor functions. In this situation, eye movements become a sensitive indicator of cognitive processing capacity. We evaluated changes in eye movement patterns made by young and older adults during reading tasks which vary in contextual complexity in order to detect subtle cognitive changes associated with normal aging.

This method of tracking eye position proved to be useful to identify and negate eye movement artifacts in algorithms used to monitor EEG signals in the treatment of epilsepsy.

Images, etc.: Here are some images related to the eye movements & cognition project.

Related publications:


Intracranial retinal transplants:

One set of goals for these investigations include 1) evaluating the functional consequences of neural plasticity during development and aging, 2) study of interactions among transplanted neurons and host neural systems, 3) determining if it is possible to enhance efficiency of retinal function experimentally, and 4) the correlation of structural and functional features contributing to optimal efficiency in transplanted and normal retinae. Findings emerging from this research program will be important for understanding the capacity of an ectopic sensory input to influence normal behaviors, and factors contributing to this capacity. The findings also will have implications for the development of behaviors based on multiple inputs in the normal nervous system. Finally, the proposed studies provide an alternative model for evaluating anatomic and functional factors relating to the therapeutic potential of in oculo transplantation procedures prior to widespread clinical application of such technology.

Anatomical studies yield interesting images, and here are a few related to the retinal development & aging studies.

For a review:


Send e-mail to: Jeff Radel

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