Lecture 18: Humans in Space & Mild Traumatic Brain Injuries (PDF)

FACULTY OF KINESIOLOGY – KNES 365 Sensorimotor Neuroscience Lecture 18 Humans in Space: Adaptations in Microgravity II Date: Tuesday November 19, 2024  Outline ▪ Sensorimotor Adaptation in Space ▪ Astronaut Training and Research ...

FACULTY OF KINESIOLOGY – KNES 365 Sensorimotor Neuroscience Lecture 18 Humans in Space: Adaptations in Microgravity II Date: Tuesday November 19, 2024  Outline ▪ Sensorimotor Adaptation in Space ▪ Astronaut Training and Research  Sensorimotor Adaptations in Space Cathrine Lowrey Nick Strzalkowski Leah Bent (Post-doc Queens) (Prof. Mt. Royal U) (Prof. U Guelph) Sensorimotor Adaptations in Space Lowrey et al 2014 Sensorimotor Adaptations in Space Assessed sensitivity to vibration in astronauts before and after their stay on the ISS. Tested various frequencies (recall, we learned that the four different cutaneous receptors prefer particular frequencies). Sensorimotor Adaptations in Space Assessed sensitivity to vibration in astronauts before and after their stay on the ISS. Tested various frequencies (recall, we learned that the four different cutaneous receptors prefer particular frequencies). GT 5thMet Heel Combined for current investigation  Sensorimotor Adaptations in Space All astronauts are tested before and after their Neurocom Balance Platform stay at the ISS on the Neurocom balance platform. Postural Stabilograms show where the pressures are under your feet while you’re asked to stand still. They measure postural stability (i.e., when the black lines span a larger area, you are swaying around more). One particular test on the Neurocom is designed to be especially sensitive to disruptions in vestibular function; this test is called the “SOT-5” (SOT = Sensory Organization Test). Note: the amount they are swaying around (i.e., how unstable they were) immediately after returning (R+0) is ELEVATED relative to before (L-30), and a few days after returning (R+3) (see also slide 11). *we’ll return to balance control a little later in the course! Sensorimotor Adaptations in Space What they found was that a Foot Sole Sensitivity sub-group of “hypersensitive” astronauts showed INCREASED foot sole vibration sensitivity AND also exceptionally poor performance on the vestibular SOT-5 test on the Neurocom. They concluded that, in these astronauts, the reduction of vestibular function (as evidenced Postural Stability by poor SOT-5 performance) was likely being offset by an adaptation of foot sole cutaneous function in space (as evidenced by these same astronauts showing increases in vibration sensitivity) CDP = Computerized Dynamic Posturography (i.e., Neurocom testing) EQ = Equilibrium Score (the output of the Neurocom system). Lowrey et al 2014 Astronaut Training and Research https://www.youtube.com/watch?v=oAoHYFZz5U4 Effects of Microgravity in Space https://www.nasa.gov/  TOP HAT TIME! Please login to your Top Hat accounts now! FACULTY OF KINESIOLOGY – KNES 365 Sensorimotor Neuroscience Lecture 18 Mild Traumatic Brain Injuries (mTBI) & Concussion Date: Tuesday November 21, 2023  Outline ▪ Diffuse Axonal Damage ▪ Brain Hemorrhage ▪ Long-Term Effects – Chronic Traumatic Encephalopathy ▪ Clinical Tools for Assessing Concussion ▪ Role of Vestibular System in Concussion  Head Trauma ▪ Head trauma causes the brain to knock up against the skull. This results in axonal sheering forces that tear neurons apart. Coup: injury (contusion) that occurs under the site of initial impact with the skull. Note: there is more than one impact with the skull, as the brain sloshes around. Contre-Coup: contusion resulting from the brain contacting the skull on the side opposite from where the initial impact occurs. Head impacts are studied by recreating them in the lab and modelling brain tissue mechanics.  Head Trauma https://www.youtube.com/watch?v=UyA-6SbP6AI  Head Trauma https://www.youtube.com/watch?time_continue=25&v=vit4JBXSm_U&feature=emb_logo  Diffuse Axonal Injury ▪ Tearing the cell membrane will result in ionic imbalances that alter electrical signaling in nerve cells (i.e., resting & action potentials, action potential threshold, adaptation rates, etc.).  Diffuse Axonal Injury ▪ Tearing the cell membrane will result in ionic imbalances that alter electrical signaling in nerve cells (i.e., resting & action potentials, action potential threshold, adaptation rates, etc.).  Diffuse Axonal Injury ▪ If the damage is severe enough, hyperintense (white-coloured) regions appear along white matter tracts in brain imaging scans. ▪ Two types of brain scans are commonly used: Computed Tomography (CT scan) and Magnetic Resonance Imaging (MRI scan). More on these techniques in our last lecture. Most “sub-concussive” impacts will NOT show any clear hyperintense regions, however, DAI is still occurring at the microscopic level. ARROWS show hyperintense regions where DAI has occurred. Seki et al 2005  Diffuse Axonal Injury https://www.youtube.com/watch?v=55u5Ivx31og  Diffuse Axonal Injury https://www.youtube.com/watch?v=sxh3z12kXjQ  Hematomas ▪ If the damage is severe enough, another major concern is bleeding (HEMATOMA) from tearing of blood vessels, which can be fatal. Shiel, 2018 Bailey, 2019  Brain Hemorrhage ▪ If the damage is severe enough, another major concern is bleeding (HEMATOMA) from tearing of blood vessels, which can be fatal. “Acute subdural hematoma. Axial non-enhanced CT in a head-injured patient with rapid clinical deterioration. The high-density crescent-shaped fluid collection spreads diffusely over the underlying right hemisphere. The midline is deviated to the left. Decompression surgery was performed, and SDH was evacuated.” “Traumatic intracerebral hematoma. Axial non-enhanced CT scan shows a high-density hematoma in a right frontal subcortical region”. Subdural hematoma Intracerebral hematoma Seki et al 2005  Brain Hemorrhage ▪ If the damage is severe enough, another major concern is bleeding (HEMATOMA) from tearing of blood vessels, which can be fatal. There have been multiple deaths in boxing (one right here in Alberta – Tim Hague) as a result of hematomas sustained from severe head trauma. https://postmedia.us.janrainsso.com/static/server.html?origin=https%3A%2F%2Fcalgarysun.com%2Fsports%2Fother-sports%2Fboxing-deaths-could-have-been-prevented  Chronic Traumatic Encephalopathy (CTE) ▪ Chronic exposure to head trauma (e.g., from a career in football or military) leads to a progress neurological disorder called CTE. ▪ Autopsies indicate pronounced damage to the nervous system. Normal Severe CTE Symptoms of CTE progressively worsen across the lifespan, Darker staining and are typically associated with changes in personality is from build-ups of protein from (impulsivity, aggression), and reductions in memory and damaged cells. other cognitive functions. Story of Dr. Bennet Omalu  Chronic Traumatic Encephalopathy (CTE) https://www.youtube.com/watch?v=ZfCaxDfGQ2Q&feature=emb_logo  Clinical Tools for Assessing Concussion ▪ Glasgow Coma Scale is one tool used in the clinic to rate symptoms of concussion. It involves having the patient open their eyes, answer questions (where are you? What day is it?), and asking them to make voluntary movements.  Clinical Tools for Assessing Concussion ▪ Sports Concussion Assessment Tool 5 (SCAT-5) is currently the most widely used scale for rating symptoms of concussion. Participants provide a rating score for various different symptoms. STEP 3 (continued)  Clinical Tools for Assessing Concussion ▪ HeadCheck Health is an app-based tool that is used by professional (CFL, MLS, NLL) and amateur sports leagues to track concussion testing and monitor compliance with return-to-play protocols.  Clinical Tools for Assessing Concussion ▪ Protxx is a company that makes a wearable (head-mounted) accelerometer that measures balance performance. Their app- based test is able to detect balance impairments associated with concussion (tested in football players and military personnel).  Role of Vestibular System in Concussion ▪ Head trauma is accompanied by large accelerations of the head, which will damage the vestibular hair cells (much like high-intensity sound damages auditory hair cells). Being punched results in the largest rotational accelerations compared to other impacts (falling, body checks, puck-to-head). Boxing has higher rotational accelerations, football has higher linear translations. Viano et al 2005 Hoshizaki et al 2014  Role of Vestibular System in Concussion ▪ Removing sensory inputs (“sway referencing”). Here the ankle bends when the body sways Sensory Organization Tests (1-6) around, providing somatosensory Information. Neurocom Platform Here optic flow information is reduced because the visual scene moves with you. Note: “sway referenced” means that it is moving along with your Here the ankle is held LOCKED AT 90°, meaning postural sway. there is reduced activation of somatosensory receptors.  Role of Vestibular System in Concussion SOT tests may provide a useful method for diagnosing and rehabilitating concussions. The SOT-5 is particularly sensitive to vestibular Anterolateral Sway dysfunction. Sosnoff et al 2011  Stochastic Vestibular Stimulation (SVS) Banman et al (2021) 34  Role of Vestibular System in Concussion ▪ Career fighters have lower and later VSR responses, which is strongly correlated to the number of RHI events. RHI = Repetitive Head Impact SLR * VSR Amplitude MLR * Fighters show advanced aging of their vestibular system (they look as if they are twice their actual age!!!) SLR = Short Latency Response Banman et al (2021) 35 MLR = Medium Latency Reponses  Role of Vestibular System in Concussion ▪ Even at lighter intensities during sparring matches, we are observing an acute drop in vestibulospinal reflex amplitude in lower-limb muscles (medial gastrocnemius in this case). Electrical Vestibular Stimulation VSR Amplitude Banman et al 2019 PROTXX EVS Unit 37 PROTXX 38  EVS Stimulation Protxx Sensor X Axis With EVS (0-3Hz) Protxx Sensor X Axis Without EVS 39 Ring-Side Science!! 40