No description available.

How behaviors are generated by neural circuits is one of the central questions in neurobiology. Under standard culture conditions, Caenorhabditis elegans travel by propagating sinusoidal waves, moving primarily forward, punctuated by brief runs of backing. How these behaviors are generated and altered is not well understood. Using a combination of behavioral analyses and neuronal imaging, I reveal that an activity imbalance between cholinergic A- and B-motoneurons is the key determinant of directional locomotion. Furthermore, heterotypic gap junctions that couple command interneurons and motoneurons of the backward motor circuit, mediated by innexins UNC-7 in AVA and UNC-9 in A-motoneurons, respectively, establish the B>A activity pattern required for forward movement. Loss of this coupling results in both the hyperactivation of AVA backward interneurons revealing the unregulated, endogenous activity of A-motoneurons. With equal A-motoneuron activity levels as B-motoneurons, innexin mutant animals exhibit irregular body bending (kinking) instead of executing forward motion, as well as increased backing. Through a genetic screen, I identified two stomatin-like proteins as regulators of innexin UNC-9 activity that affect C. elegans’ directional movement. The loss of function of stomatin-like unc-1 leads to the same kinker phenotype as unc-7 or unc-9 mutants. Like UNC-9, UNC-1 functions primarily in the A-motoneurons to allow forward motion, suggesting that UNC-1 is required for effective UNC-7-UNC-9 coupling between AVA and A-motoneurons. Dominant mutations in UNC-1, and another stomatin-like protein STO-6, exhibit genetic interactions with these innexin mutants. These mutations partially restore the forward movement of unc-7 mutants, in an UNC-9-dependent manner, indicating that they regulate UNC-9 channel activity in motoneurons to re-establish the B>A-motoneuron activity pattern in the absence of heterotypic gap junctions between interneurons and motoneurons. These studies describe a role of gap junctions as regulators of circuit dynamics by establishing an imbalanced motoneuron activity pattern that favors forward motion, which can be modulated by upper layer inputs. This study also identifies stomatin-like regulators of innexin hemichannel and gap junction function. Future work will focus on understanding mechanisms through which these stomatins regulate the activity of specific innexin channels in C. elegans motoneurons, as well as their contribution to the dynamic output of the C. elegans motor circuit.

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The development of swimming was investigated in zebrafish aged 1.5 to 5 days postfertilization by examining both the swimming behavior and its generation by the nervous system. Upon hatching (at day 2), swimming is undirected and occurs in sustained bursts of high frequency (mean = 67 Hz) tail undulations. By 4 days, the swimming pattern matures to a more directed, less erratic, beat-and-glide pattern where slower (mean = 35 Hz) tail undulations, lasting ∼200 ms, alternate with longer gliding rest periods. Swimming is powered by two classes of embryonic muscles (embryonic red, ER and white, EW) that are electrically coupled within (but not between) classes and have physiological properties similar to vertebrate tonic and twitch muscle, respectively. ER fibers have a lower chloride ion permeability than EW fibers and do not have sodium dependent action potentials. In paralyzed preparations, motoneurons and muscle fibers received coordinated excitatory synaptic activity (with left to right alternation and head to tail propagation) corresponding to either burst or beat-and-glide swimming. ER muscle was de-recruited at the fastest swimming rates and EW fibers dropped out at the slowest swimming rates. Rhythmic motoneuron output was generated by a phasic glutamatergic and a largely tonic glycinergic synaptic drive. Glutamatergic synapses had either or both AMPA/kainate and NMDA receptors and the kinetics of these synaptic currents were fixed throughout the developmental period examined. When depolarized, motoneurons fired high frequency (up to 800 Hz) bursts of action potentials that rapidly accommodated (within ∼20 ms) due to voltage and calcium dependent outwardly rectifying conductances. These intrinsic motoneuron properties are hypothesized to interact with the rhythmic synaptic drive to pattern motor output (at ∼25--75 Hz) to locomotor muscles. The neural generation of swimming in developing zebrafish is thus fundamentally similar to locomotion in adu

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No description available.

Locomotion automation is a very challenging and complex problem to solve. Besides the obvious navigation problems, there are also problems regarding the environment in which navigation has to be performed. Terrains with obstacles such as rocks, steps or high inclinations, among others, pose serious difficulties to normal wheeled vehicles. The flexibility of legged locomotion is ideal for these types of terrains but this alternate form of locomotion brings with it its own challenges to be solved, caused by the high number of degrees of freedom inherent to it. This problem is usually computationally intensive, so an alternative, using simple and hardware amenable bio-inspired systems, was studied. The goal of this thesis was to investigate if using a biologically inspired learning algorithm, integrated in a fully biologically inspired system, can improve its performance on irregular terrain by adapting its gait to deal with obstacles in its path. At first, two different versions of a learning algorithm based on unsupervised reinforcement learning were developed and evaluated. These systems worked by correlating different events and using them to adjust the behaviour of the system so that it predicts difficult situations and adapts to them beforehand. The difference between these versions was the implementation of a mechanism that allowed for some correlations to be forgotten and suppressed by stronger ones. Secondly, a depth from motion system was tested with unsatisfactory results. The source of the problems are analysed and discussed. An alternative system based on stereo vision was implemented, together with an obstacle detection system based on neuron and synaptic models. It is shown that this system is able to detect obstacles in the path of the robot. After the individual systems were completed, they were integrated together and the system performance was evaluated in a series of 3D simulations using various scenarios. These simulations allowed to conclude that both learning systems were able to adapt to simple scenarios but only the one capable of forgetting past correlations was able to adjust correctly in the more complex experiments.

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The purpose of this study was to determine the functional changes due to the Graston Therapeutic Technique (GTT) in an animal model. This study attempted to verify the biomechanical changes associated with the Graston Therapeutic Technique (GTT) in order to possibly apply it to humans as a major physical therapy modality. Eighteen adult, male Sprague-Dawley rats were assigned randomly to three groups. The groups were classified as follows: (a) no injured plus GTT treatment, (b) injured minus GTT treatment, (c) injured plus GTT treatment. The GTT therapy began after one week following injury to allow for optimum inflammation and scar formation. The animals receiving GTT had six treatments over the course of two weeks. Running tests were performed on a treadmill at a velocity of 22 cm/s prior to induction of injury, one week following injury, two weeks following injury, and three weeksfollowing injury in the experimental groups. Variables analyzed were knee and ankle range of motion (ROM), stride length (SL), and stride frequency (SF). Significance of effect between experimental groups were determined by repeated measures one-way ANOVA, Scheffe's post hoc test, and Newman-Keuls post hoc test. The stride length and stride frequency results of the present study appeared to indicate that the Graston Therapeutic Technique (GTT) had an effect on changes in the stride length and stride frequency after injury. Statistical analysis between observations for the GTT plus groups indicated a significant difference in the swing phase of knee ROM. The results of this study also indicated that the Graston Therapeutic Technique may have had an influence on knee joint range of motion. / School of Physical Education

The purpose of this study was to describe women collegiate swimmers' armstroke sequence at selected velocities. In addition, this study was designed to determine the timing angle during the course of a stroke cycle. Seven members of the Ball State University Women's Swim Team were asked to participate in this study. The test consisted of the subject swimming approximately fifteen meters freestyle (front crawl) at stroke rates of 24, 30, 40, 48, 60 strokes per minute. The subjects attempted three trials at each stroke rate, on a continuum from slow to fast. The following parameters were determined from video analysis: stroke length (SL), velocity (m/s), time of one complete stroke cycle (SCT), timing between the arm cycles (RAE), recovery arm entry as a percentage of SCT (RAE%) and the timing angle. A correlation between the timing angle and V of r = 0.48 was found to be significant at the 0.05 level. A correlation between the SCT and the timing angle of r = -0.62 was found to be significant at the 0.05 level. A correlation of r = -0.43 between SL and the timing angle of less than 90 degrees is believed to benefit theangle was found to be significant at the 0.05 level. This indicates that as the swimmers' SCT decreased, the timing angle increased. And, as the swimmers' SL decreased the timing angle increased. It appears that timing angles increase with increasing V. The mean timing angle for ninety trials was 66.03 degrees with a SD of 17.68. This study indicates that women collegiate swimmers use a timing angle of less than 90 degrees. A timing swimmers' body position, balance and SL. / School of Physical Education