Some new research just came out in Neuron that is incredibly relevant to the work I do in my lab. The myriad (billions) of granule cells in the cerebellum send their axons, the parallel fibers, to the purkinje cells (pictured below). This junction is of utmost importance…excitation of purkinje cells leads to the inhibition of behavior, whereas as inhibition of the purkinje cells generally leads to motor movement. While common sense and many experiments have shown that movement-inducing inhibition of the purkinje cells (called “Long-Term Depression,” or LTD) is vital for motor learning, new research like this points towards the role of excitation of the purkinje cells (called “Long-Term Potentiation,” or LTP), and thus inhibition of motor behavior, as well. I study motor learning in the Medina lab at Upenn, with a focus on the parallel fiber-purkinje cell synapse. This research certainly adds more to the puzzle of motor learning…the mystery grows…
Check out the “video abstract” at http://www.cell.com/neuron/
image/Ramon y Cajal
No two neurons are the same. Even neurons of the same type (i.e. purkinje cells) behave differently. This fact is often overlooked as an important functional feature of the brain, and instead chalked up to biological impreciseness. In their recent Nature article, Krishnan Padmanabhan and Nathaniel Urban think there’s an important reason behind all the diversity. They studied the “intrinsic differences” in the molecular signatures and firing behaviors of mitral cells in the mouse olfactory bulb, and by differentially stimulating different cells concluded that:
Although a number of mechanisms have been proposed to account for the origin and extent of these intrinsic differences, we found that differences in intrinsic biophysical heterogeneity can be important [for] neural coding.
In other words, the intrinsic differences between neurons are not biological mistakes – they are adaptive functions for the complex neural coding of stimulus information.
100 billion neurons, and each one is functionally different? I’m having trouble coding that one…
A review published last week by two Swiss neuroscientists in Nature Neuroscience argues that psychedelic drugs, like psilocybin (“mushrooms”) and LSD, have serious therapeutic applications:
“Recent behavioural and neuroimaging data show that psychedelics modulate neural circuits that have been implicated in mood and affective disorders, and can reduce the clinical symptoms of these disorders (Vollenweider & Kometer, 2010).”
Psychedelics have strong effects on the brain’s glutamatergic and serotonergic pathways, which malfunction in patients with clinical depression and anxiety. Many lines of evidence show that psychedelics can alleviate the symptoms of depression and anxiety using relatively small doses. There are obvious political hurdles to be mounted for any of these drugs to make there way into more research labs, and potentially into pharmacies, but the recent relative success of medical marijuana campaigns may have laid important tracks for thorough research on the positive effects of “taboo” drugs.
An architecture firm has submitted a design for the Icelandic High-Voltage Electrical Pylon International Design Competition (I’m preparing my submission as we speak) which puts forth the model pictured below: massive human-shaped pylons carrying electricity cables across the country’s beautifully stark landscape.
The official proposal reads: “Like the statues of Easter Island, it is envisioned that these one hundred and fifty foot tall, modern caryatids will take on a quiet authority, belonging to their landscape yet serving the people, silently transporting electricity across all terrain, day and night, sunshine or snow.”
For more images and information check out this article at Wired.
A new study from the University of Illinois shows that gene expression in a bee’s brain changes when the bee perceives long and short distances. The researchers used an ingenious little trick - If the bee’s environment is “busy” (patterned walls with lots of disordered images) rather than “sparse” (walls with a more plain pattern), it perceives its traveling distance as longer. This perception is measured by looking at the bee’s “dance,” the behavior it uses to communicate the location of food sources. The dances are different in both experimental situations, even though both distances are the same. Furthermore, gene expression in brain areas involved in vision and memory differs between the two environments, implying that there are genetic factors responsive to distance (and apparently prone to error). This work furthers the idea the genome isn’t merely a static set of instructions for organisms – it’s dynamic and responsive.