In October my brothers talked me into running in my first marathon. We traveled down to Washington D.C. to join 20,000+ of our newest friends to run the Marine Corps Marathon. The entire 26.2 mile course was lined with supporters that tirelessly cheered everyone on, no matter how fast or how slow we were. Running through the nation’s capital and along the National Mall with my brothers and so many supporters made my first marathon incredibly memorable.
On May 8, 2013, I started hiking North from Springer Mountain, Georgia. It was the beginning of an adventure that I had been dreaming about for my entire life, the adventure of thru-hiking the Appalachian Trail. I followed the white blazes (trail markers) as the Appalachian Trail bobbed up and down (515,000 feet of total elevation gain/loss) for 2,180+ miles along the backbone of the East Coast, the Appalachian Mountain Chain. I passed through 14 states, saw 18 bears, heard tornado sirens for the first time, almost tripped on a porcupine, saw more rattlesnakes than I wanted, lost fifty pounds, met new and amazing people, and had my faith in humanity renewed before reaching my destination at Mount Katahdin in Maine on October 4, 2013.
Tags: Appalachian Trail
On April 13, 2013 I participated in the 50th annual River Rat Race in my hometown. It is a fun and crazy canoe race where the real goal (at least for me) is to stay dry. That river is very very cold! This year there were over 300 canoes entered into the race. Starting place along the river is determined by a lottery held the night before the race. We drew #148, so were right in the middle of the pack.
Being in the middle of the pack made it an even more exciting race for me than usual. Canoes were dumping even before the race started. Often the canoes were so thick in the river that there wasn’t space for me to put my paddle in the water. Despite the craziness we were able to keep our canoe going downstream and afloat. It was another great race down the river!
Tuning and timing in mammalian type I hair cells and calyceal synapses
Jocelyn E. Songer and Ruth Anne Eatock
Departments of Otology, Laryngology, and Neurobiology, Harvard Medical School, Boston, MA 02115
Abstract: Afferent nerve fibers in the central zones of vestibular epithelia form calyceal endings around type I hair cells and have phasic response properties that emphasize fast head motions. We investigated how stages from hair-cell transduction to calyceal spiking contribute tuning and timing to central (striolar)-zone afferents of the rat saccular epithelium. In an excised preparation, we deflected individual hair bundles with rigid probes driven with steps and sinusoids (0.5-500 Hz) and recorded whole-cell responses from hair cells and calyces at room temperature and body temperature. In immature hair cells and calyces (postnatal days, P, 1-4), tuning sharpened at each stage. Transducer adaptation and membrane charging time produced bandpass filtering of the receptor potential with best frequencies of 10-30 Hz and phase leads below 10 Hz. For small stimuli, electrical resonances sharply tuned the hair cell membrane in the frequency range 5-40 Hz. The synaptic delay of quantal transmission added a phase lag above 10 Hz. The influence of spike thresholds at the calyceal spike initiation stage sharpened tuning and advanced response phase. Two additional mechanisms strongly advanced response phase above 10 Hz when present: maturing (P7-9) type I hair cells acquired low-voltage-activated channels that shortened the rise time of the receptor potential, and some calyces had non-quantal transmission with little synaptic delay. By reducing response time, the identified inner-ear mechanisms (transducer adaptation, low-voltage-activated channels, non-quantal transmission, and spike triggering) may compensate for transmission delays in vestibular reflex pathways and help stabilize posture and gaze during rapid head motions.
The Journal of Neuroscience, 20 February 2013, 33(8):3706-3724; doi:10.1523/JNEUROSCI.4067-12.2013
Diverse Firing Patterns in Calyces of the Immature Rat Saccule
Jocelyn E. Songer and Ruth Anne Eatock
Background: The mammalian vestibular epithelium has a unique synapse between the sensory hair cell and the post-synaptic afferent terminal: the calyx. The calyx envelops the cell body of one or more type I hair cells. Two classes of vestibular afferents form calyceal endings: 1) calyx-only fibers innervating the central, striolar, zone of the epithelium and 2) dimorphic fibers innervating the striolar or extrastriolar zones and forming both bouton and calyceal endings on hair cells. Recordings from isolated vestibular ganglion show two firing patterns in response to depolarizing current steps, transient and sustained. We hypothesize that calyces from the striolar zone will have transient responses and irregular spontaneous activity whereas extrastriolar calyces will have sustained responses and regular spontaneous activity.
Methods: Whole-cell current clamp recordings were made from calyces in a semi-intact preparation of the immature (postnatal days 4-9) rat saccular epithelium and attached nerve. Both Nomarski optics and the fluorescent dye rhodamine were used to identify the morphology and zones of the afferents.
Results: Recordings from striolar calyces showed transient responses, a single spike at the onset of depolarizing stimuli consistent with recordings from vestibular ganglion. Spontaneous firing was observed in a subset of striolar calyces (5/24). These striolar calyces had a low rate of spontaneous activity, and irregular firing patterns (rate=6±2 spikes/s, CV=1.14±0.25, fanofactor=0.24±0.06, n=5), consistent with in vivo recordings from striolar afferents. The majority of extrastriolar calyces responded to depolarizing current steps with sustained responses (12/16). The spontaneous activity from these extrastriolar dimorphs (9/16) had a higher rate (15±2 spikes/s, p<0.014), and was more regular than that of the striolar calyces (CV=0.22±0.08, p<9e-4 and fanofactor=0.013±0.008, p<1.8e-4). To investigate the possibility that the low spike rates in striolar afferents may have resulted from the difference between body temperature and room temperature, we recorded from complex calyces at 35-37°C, 4/7 of these calyces fired spontaneously and these had higher firing rates than those at 25-29° (thermal Q10 of 3).
Conclusions: Striolar calyces had transient responses and irregular spontaneous activity (when present). These spontaneously active calyces were all from P7 or P8 animals, raising the possibility that spike activity increases with maturation. Extrastriolar calyces had sustained responses and regular spontaneous activity. These results suggest that in vivo differences in spike regularity between the striolar and extrastriolar zones are preserved in our preparation.
Association for Research in Otolyrngology Midwinter Meeting. (19:131)
Date: 16–20 February 2013
Location: Baltimore, Maryland (USA)
Quebec City does winter right! I have lived in Massachusetts all of my life and I tend to think of myself as being immune to the cold and crazy winter weather. But this time, instead of sticking around Boston for Nemo the blizzard of 2013, I escaped to Quebec City. Instead of thinking of the snow and ice as a plague and a disaster, Quebec City highlights the beauty associated with the bitter cold and darkness of the North East.
It snowed the entire time we were there, and it was bitterly cold. We started the trip with a night at the ice hotel in outskirts in Quebec City. It ice hotel was phenomenally beautiful, but an icy icy chillingly cold beautiful. The lights gave the illusion of warmth, but even as bundled up as we could get we were cold. The hot tubs and saunas that they provided 24/7 didn’t quite manage to keep up with the chilling temperatures, so we found ourselves retreating to our room and our cozy sleeping bags in the search for warmth. Despite concerns that we’d have a chilly night, as soon as we zipped the sleeping bags up we were toasty warm… it wasn’t until we woke in the morning that the frigid reality crept back into our bones.
We were definitely looking forward to a warming up before setting out for the Winter Carnival. Despite the cold we ventured out to the Winter Carnival and were rewarded by the ice sculptures. I’ve never actually seen professional ice sculptures and it was impressive to find row after row of them… done by both local and international artists. Going back at night was even better, with each sculpture carefully lit to bring out even more dimension. The light shows scattered throughout the city kept drawing us out despite the cold.
In continuance with my goal of running more in 2013, I ended up signing up for the Rebel Race obstacle race. It was a cold November day full of mud and water, but it was tons of fun. I did something that I’ve never done before, a hanging rope traverse! Next time I do it, I hope to have a bit more upper body strength, and I think it would be nice to be warmed up a little bit better first.
No matter how busy and crazy life seems I try to get out and into the mountains. Mt Alander, in western Massachusetts is one of my favorite places to introduce people to backpacking. It’s a fairly easy hike with lots of exposure and stunning views. There’s a great ridgewalk and off season it isn’t too crowded.
What do you do on a rainy day in Ireland? We decided that the clear answer was to go and explore a Castle, so we made our way up to Ashford Castle. As we wandered the gardens in the rain we encountered a sign for “Ireland’s School of Falconry.” It was the perfect thing for us to do… we wandered the grounds of the castle flying our birds. It was tons of fun! As we finished up, the sun came out and one of Ireland’s famous rainbows arced over the castle.