Biology subjects

Tyler, S.

Publications and source records attributed to Tyler, S..

3 recordsLinked to original sources

bioRxiv2022

Selective brain cooling monitored by CT perfusion as adjuvant therapy in a porcine model of severe ischemic stroke

Despite the advances in ischemic stroke treatment, not all patients are eligible for or fully recovered after recanalization therapies. Therapeutic hypothermia could be adjuvant therapy that optimizes the beneficial effect of reperfusion. While conventional whole-body cooling has severe adverse effects, selective brain cooling has emerged as an attractive alternative. However, clinical application is limited by the lack of optimal delivery methods and unknown treatment parameters. Optimal parameters may depend on injury levels and monitoring cerebral perfusion may provide valuable information. Here, we show that selective brain cooling via our in-house developed Vortex tube IntraNasal Cooling Instrument (VINCI), even with a clinically relevant delay in treatment, can attenuate subacute injuries in animals with severe ischemic stroke. The treatment responses of selective brain cooling were characterized by CT Perfusion (CTP). The predicted lesion volume by CTP matched the true infarct volume by histology when the brain temperature was decreased by 5{degrees}C from normothermia. More importantly, we found that global hyperemia (high cerebral blood flow) before rewarming could be an early manifestation of poor treatment outcomes. Altogether, our study shows that VINCI-enabled brain cooling could be guided by CTP imaging as adjuvant therapy for severe ischemic stroke. This work lays the groundwork toward individualized selective brain cooling. Significance StatementNot all patients suffering from ischemic stroke are eligible or fully recovered after recanalization therapies. Therapeutic hypothermia could be an adjuvant therapy, but the clinical application is hindered by the delivery methods. The optimum treatment depth and duration are also unknown, and they may depend on the injury level. We developed a non-invasive selective brain cooling device, Vortex tube IntraNasal Cooling Instrument (VINCI). The treatment responses were characterized by CT Perfusion (CTP). Global hyperemia (high cerebral blood flow) was identified and could be an early manifestation of poor treatment outcomes. Our work shows that VINCI-enabled brain cooling could be guided by CTP imaging as adjuvant therapy for ischemic stroke. This work also lays the groundwork toward individualized selective brain cooling.

neuroscience↗

bioRxiv2022

The role of the parietal lobe in task-irrelevant suppression during learning

BackgroundAttention optimizes the selection of visual information, while suppressing irrelevant visual input through cortical mechanisms that are still unclear. We set to investigate these processes using an attention task with an embedded to-be-ignored interfering visual input. ObjectiveWe delivered electrical stimulation to attention-related brain areas to modulate these facilitatory/inhibitory attentional mechanisms. We asked whether training on a task while being simultaneously exposed to visual features from a different task tested at baseline and post-training might influence performance on the baseline task. MethodsIn Experiment one, subjects performed an orientation discrimination (OD) task using a pair of gratings presented at individuals psychophysical threshold. We then trained participants over multiple sessions on a temporal order judgment task (TOJ), using the exact same gratings but presented with different time offsets. On the last session we re-tested OD. We coupled training with transcranial random noise stimulation (tRNS) over the parietal cortex, the human middle temporal area or sham, in three separate groups. In Experiment two, subjects performed the same OD task at baseline and post-training, while tRNS was delivered at rest during training. ResultsResults showed that tRNS over parietal cortex facilitated learning of the trained task. Moreover, we found a detrimental effect on OD when subjects received parietal tRNS coupled with training, but a benefit on OD when subjects received stimulation while at rest. ConclusionsThese results clearly indicate that task-irrelevant information is actively suppressed during learning, and that this prioritization mechanism of selection likely resides in the parietal cortex.

neuroscience↗

bioRxiv2020

Attention network modulation via tRNS correlates with attention gain

Transcranial Random Noise Stimulation (tRNS) can enhance vision in the healthy and diseased brain. Yet, the impact of tRNS on large-scale cortical networks is still unknown. We investigated the impact of tRNS coupled with behavioral training on resting-state functional connectivity and attention. We trained human subjects for four consecutive days on two attention tasks, while receiving tRNS over the intraparietal sulci, the middle temporal areas, or sham stimulation. We measured resting state functional connectivity of nodes of the dorsal and ventral attention network (DVAN) before and after training. We found a strong behavioral improvement and increased connectivity within the DVAN after parietal stimulation only. Crucially, behavioral improvement positively correlated with connectivity measures. We conclude changes in connectivity is a marker for the enduring effect of tRNS upon behavior. Our results suggest that tRNS has strong potential to augment cognitive capacity in healthy individuals and promote recovery in the neurological population.

neuroscience↗