2002 — 2004 |
Busettini, Claudio |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Fmr Imaging of Eye Stabilization Processes @ University of Alabama At Birmingham
DESCRIPTION: (Applicant's Abstract) Vision requires the images projected on the retina to remain stable. Visual eye-stabilization mechanisms detect perturbations of the retinal images and generate eye movements aimed at compensating for such disturbances. In humans and monkeys, with sophisticated foveal binocular vision, there are ultra-fast, highly specialized cortical eye-stabilization systems able to decode and compensate for the complex visual perturbations caused by the observer's own motion in a structured three-dimensional environment. The proposed pilot study will be centered on developing the technology and the experimental protocols needed for the functional magnetic resonance imaging (fMRI) of such processes in alert behaving monkeys and the acquisition of preliminary data on which a in-depth study proposal will then be developed. Extensive behavioral and single-unit studies in monkeys have shown that, even if cortical in origin, the neuronal activation and related oculomotor responses associated with such systems are closely time-locked to the stimulus onset and of machine-like repeatability. This makes them ideal for fMRI studies. Furthermore, there is strong evidence that such responses are generated by cortical areas directly linked to visual perception. A systematic manipulation of the visual stimuli can therefore be used to probe the underlying neuronal processes on which perception is then constructed. Their reflex-like nature will also be used as tool for the optimization of fMRI sequences and extraction algorithms, and the analysis of the temporal development of the fMRI signal, included the recently discovered "fast response". The matching of neuronal data from invasive studies with fMRI data obtained with identical protocols in the same animals will be an invaluable starting point for the interpretation of similar fMRI studies on humans. Comparative studies of those responses have highlighted almost astonishing similarities between the two species, suggesting a similar underlying neuronal structure. There are many open questions regarding the neuro anatomical and functional correspondences between monkeys and humans and the goal of this pilot study is to propose a novel, powerful tool for solving such issues of critical importance for the understanding of the human brain.
|
0.987 |
2006 — 2009 |
Busettini, Claudio |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Neural Organization of Eye Movements in Depth @ University of Alabama At Birmingham
[unreadable] DESCRIPTION (provided by applicant): Disconjugate oculomotor responses, where the two eyes rotate by different amounts, are often needed. Hering's law of equal innervation states that there are two groups of oculomotor commands. Conjugate commands rotate the eyes in the same amount in the same direction similarly to a yoked pair. Vergence commands control the angle between the eyes by rotating the eyes in same amount in the opposite direction. Any disconjugate eye rotation can be obtained by appropriate conjugate and vergence commands. Recent evidence shows that some disconjugate responses may be driven by independent left- and right-eye asymmetric commands, perhaps directly reaching the motor neurons outside the vergence pathway. Are these putative monocular signals functionally significant? We will address this question by estimating the percentage of disconjugate command encoded by the vergence system directly at the neuronal level. If Hering's law is correct, the vergence system must account for the entire disconjugate response, independently of the type of stimulus or the oculomotor system in which it was generated. These estimates will be done during: 1) voluntary transfers of gaze in depth between stationary targets; 2) voluntary smooth tracking of small objects moving in depth; 3) ultra-short latency reflexive visual stabilization responses; and 4) linear vestibulo-ocular responses. Neural targets for the single-unit recordings will be the vergence-related cells in midbrain. Binocular horizontal, vertical, and torsional eye movements will be recorded together with the neural activity of these cells. High-field anatomical and functional MRI will help localize these areas. Visual function is severely degraded by double vision. At least 4% of the US population is affected by long- term deficits in binocular alignment, such as strabismus and amblyopia. The understanding of how disconjugate commands are generated and delivered to the extraocular muscles is of critical importance in developing a correct clinical management of oculomotor disorders affecting binocular alignment, both as diagnosis of the source of the oculomotor deficit and the selection of the proper surgical or optical intervention. Knowledge of the neural substrate of these mechanisms will be a crucial tool in the understanding of the oculomotor adaptive processes that help a patient recalibrate his/her eye movement commands to regain, or at least partially improve, binocularity, which are poorly understood. [unreadable] [unreadable] [unreadable]
|
0.987 |
2015 — 2016 |
Bolding, Mark S (co-PI) [⬀] Busettini, Claudio Liu, Lei |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Passive Eye Response as a Surrogate For Brain Response to Head Acceleration @ University of Alabama At Birmingham
? DESCRIPTION (provided by applicant): Mild Traumatic Brain Injury (mTBI) is a high prevalence injury, caused by the displacement and deformation of the brain in the skull during head/body impacts. Athletes in contact sports at all levels are a high-risk population. It is vitaly important to identify athletes receiving potentially concussive blows on the field in order to prevent further injury and long-term neurological damage. For this purpose, a lot of research has been devoted to on- field monitoring of head accelerations (HACC) following the hypothesis that a high HACC is associated with a higher risk of concussion. So far, it appears that the link between HACC and clinical outcome of mTBI is elusive, because it is not clear how HACC recorded on-field translates to brain displacement and deformation. There is no method that can directly assess brain responses to body/head impacts in live human beings engaged in high-risk activities at this moment. It is recognized that other organs in the head may undergo similar displacement and deformation as the brain during impacts and thus may serve as a surrogate for inferring brain responses. One of these organs is the eye. It has been demonstrated that the eye and the surrounding tissue (the eye mass) undergo a passive (not neurally controlled) mechanical displacement and deformation in the eye socket in a short time window immediately after a HACC. It is thus hypothesized that a direct assessment of the passive eye response (PER) to HACC can be used to better infer brain response to body/head impact, and consequently, can offer a better chance to predict mTBI than HACC itself. Three specific aims will be pursued to test the hypothesis above. (1) Develop a tethered eye sensor that is made of an array of strain gauges packed in a silicone hydrogel wafer and that can be inserted in the inferior cul-de-sac of a human eye. The eye sensor measures dynamic strains at several locations and thus provides real time assessment of eye mass response to impact. It will be tested and refined using an anatomic head model. (2) Record PER induced by daily activities that are known to produce mild, non-concussive HACC. Twenty young, normal human participants will be asked to perform tasks such as sitting into a chair, standing up, walking, running on a treadmill, jumping and moving the eyes while the PER is monitored with the eye sensor. (3) Brain displacement and deformation caused by mild, non-concussive linear and angular HACC will be imaged using tagged MRI in 5 young normal human participants while the HACC and PER are monitored. These experiments will quantify the link between HACC, PER and brain responses, and will lay the foundation for further development of a wireless eye sensor for athletes to wear during games and to identify those who may have received concussive blows.
|
0.987 |