Biology subjects

Awosika, O. O.

Publications and source records attributed to Awosika, O. O..

3 recordsLinked to original sources

bioRxiv2023

Evaluating the neural underpinnings of motivation for walking exercise

BackgroundMotivation is critically important for rehabilitation, exercise, and motor performance, but its neural basis is poorly understood. Recent correlational research suggests that superior frontal gyrus medial area 9 (SFG9m) may be involved in motivation for walking activity. This study experimentally evaluated brain activity changes in periods of additional motivation during walking exercise, and tested how these brain activity changes relate to self-reported exercise motivation and walking speed. MethodsNon-disabled adults (N=26; 65% female; 25 {+/-} 5 years old) performed a vigorous exercise experiment involving 20 trials of maximal speed overground walking. Half of the trials were randomized to include extra motivation stimuli (lap timer, tracked best lap time and verbal encouragement). Wearable nearinfrared spectroscopy measured oxygenated hemoglobin responses ({Delta}HbO2) from frontal lobe regions, including the SFG9m, primary motor, dorsolateral prefrontal, anterior prefrontal, supplementary motor and dorsal premotor cortices. ResultsCompared with standard trials, participants walked faster during extra-motivation trials (2.67 vs. 2.43 m/s; p<0.0001) and had higher {Delta}HbO2 in all tested brain regions. This extra motivation effect on {Delta}HbO2 was greatest for SFG9m (+703 {micro}M) compared with other regions (+45 to +354 {micro}M; p[≤]0.04). Greater SFG9m activity was correlated with more self-determined motivation for exercise and faster walking speed. ConclusionsSimple motivational stimuli during walking exercise seem to upregulate widespread brain regions, especially SFG9m. This could help explain the positive effects of motivational feedback on gait outcomes observed in prior rehabilitation research. Thus, these findings provide a potential biologic basis for the benefits of motivational stimuli, elicited with clinically-feasible methods during walking exercise. Future clinical studies could build on this information to develop prognostic biomarkers and test novel brain stimulation targets for enhancing exercise motivation (e.g. SFG9m).

neuroscience↗

bioRxiv2021

Mapping the human corticoreticular pathway with multimodal delineation of the gigantocellular reticular nucleus and high-resolution diffusion tractography

The corticoreticular pathway (CRP) is a major motor tract that provides volitional input to the reticular formation motor nuclei and may be an important mediator of motor recovery after central nervous system damage. However, its cortical origins, trajectory and laterality are incompletely understood in humans. This study aimed to map the human CRP and generate an average CRP template in standard MRI space. Following recently established guidelines, we manually delineated the primary reticular formation motor nucleus (gigantocellular reticular nucleus [GRN]) using several group-mean MRI contrasts from the Human Connectome Project (HCP). CRP tractography was then performed with HCP diffusion-weighted MRI data (N=1,065) by selecting diffusion streamlines that reached both the frontal cortex and GRN. Corticospinal tract (CST) tractography was also performed for comparison. Results suggest that the human CRP has widespread origins, which overlap with the CST across most of the motor cortex and include additional exclusive inputs from the medial and anterior prefrontal cortices. The estimated CRP projected through the anterior and posterior limbs of the internal capsule before partially decussating in the midbrain tegmentum and converging bilaterally on the pontomedullary reticular formation. Thus, the CRP trajectory appears to partially overlap the CST, while being more distributed and anteromedial to the CST in the cerebrum before moving posterior to the CST in the brainstem. These findings have important implications for neurophysiologic testing, cortical stimulation and movement recovery after brain lesions. We expect that our GRN and tract maps will also facilitate future CRP research. HIGHLIGHTSO_LIThe corticoreticular pathway (CRP) is a major tract with poorly known human anatomy C_LIO_LIWe mapped the human CRP with diffusion tractography led by postmortem & animal data C_LIO_LIThe CRP appears to originate from most of the motor cortices and further anterior C_LIO_LIThe estimated CRP had distributed and bilateral projections to the brainstem C_LIO_LIThese findings have important implications for motor recovery after brain lesions C_LI

neuroscience↗

bioRxiv2021

Mapping the corticoreticular pathway from cortex-wide anterograde axonal tracing in the mouse

The corticoreticular pathway (CRP) has been implicated as an important mediator of motor recovery and rehabilitation after central nervous system damage. However, its origins, trajectory and laterality are not well understood. This study mapped the mouse CRP in comparison with the corticospinal tract (CST). We systematically searched the Allen Mouse Brain Connectivity Atlas ((C) 2011 Allen Institute for Brain Science) for experiments that used anterograde tracer injections into the right isocortex in mice. For each eligible experiment (N=607), CRP and CST projection strength were quantified by the tracer volume reaching the reticular formation motor nuclei (RFmotor) and pyramids respectively. Tracer density in each brain voxel was also correlated with RFmotor versus pyramids projection strength to explore the relative trajectories of the CRP and CST. We found significant CRP projections originating from the primary and secondary motor cortices, anterior cingulate, primary somatosensory cortex and medial prefrontal cortex. Compared with the CST, the CRP had stronger projections from each region except the primary somatosensory cortex. Ipsilateral projections were stronger than contralateral for both tracts (above the pyramidal decussation), but the CRP projected more bilaterally than the CST. The estimated CRP trajectory was anteromedial to the CST in the internal capsule and dorsal to the CST in the brainstem. Our findings reveal a widespread distribution of CRP origins and confirm strong bilateral CRP projections, theoretically increasing the potential for partial sparing after brain lesions and contralesional compensation after unilateral injury. SIGNIFICANCEThe corticoreticular pathway (CRP) provides volitional input to brainstem nuclei that generate walking command signals, facilitate balance and direct limb movements. Upregulation of this pathway appears to be a central mechanism of movement recovery after brain and spinal cord injury, but its anatomy is not well understood. We showed that the mouse CRP originates from widespread parts of the cortex, including non-motor regions, that it projects strongly to both sides of the brainstem, and that its projections are more distributed and bilateral than the corticospinal tract. These findings suggest that the CRP may be particularly resilient to complete disruption.

neuroscience↗