Saturday, September 28, 2013

Tom and Jerry - no more fear

Fear is induced by a perceived threat which causes entities to quickly pull far away from it and usually hide. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger.

Now a study at the University of California, Berkeley shows that mice may permanently shed their fear of felines when infected with a protozoan parasite Toxoplasma gondii.

The parasite can infect most mammals, including humans but can only reproduce in the feline gut, so cats need to eat animals infected with T. gondii to keep the parasite generations going.

Perhaps increasing the likelihood that it will wind up in the belly of a cat, the parasite makes infected rodents lose their innate aversion to cat urine, researchers discovered in 2000. The parasite strain was so potent that it killed the mice quickly, so researchers had no way of knowing whether the rodents’ loss of cat aversion could persist.

According to the researchers a transient infection with the parasite may permanently alter the way the rodents’ brains perceive predator threats.

Wednesday, September 25, 2013

Time and time again

For years - any opportunity I have to do any serious thinking typically and inevitably circles around time. What is it, was it always there, how do we perceive it, how is time intertwined by space (space-time) etc. And if we subscribe to Einstein's theory of relativity, there was no such thing as time before the big bang; there was no "before." Time (and space) started at a singularity (with the laws of physics broken down).

And more so, is time a feature of the universe that can be understood independently of a conscious being. That is, can we make sense of time when everything about time is perceived and processed through a lens of brain architecture?

We know for example time is processed across a a highly distributed system involving the cerebral cortex, cerebellum and basal ganglia. One particular component, the suprachiasmatic nucleus, is responsible for the circadian (or daily) rhythm, while other cell clusters appear to be capable of shorter-range (ultradian) timekeeping.

Different types of sensory information (auditory, tactile, visual, etc.) are processed at different speeds by different neural architectures. Our brain, it seems, has learned how to overcome these speed disparities, to create a temporally unified representation of the external world.

In the popular essay "Brain Time", by David Eagleman, he suggests that "if the visual brain wants to get events correct timewise, it may have only one choice: wait for the slowest information to arrive. To accomplish this, it must wait about a tenth of a second.  As long as the signals arrived within this window, viewers' brains would automatically resynchronize the signals". He goes on to say that "This brief waiting period allows the visual system to discount the various delays imposed by the early stages; however, it has the disadvantage of pushing perception into the past. There is a distinct survival advantage to operating as close to the present as possible; an animal does not want to live too far in the past.

Therefore, the tenth-of- a-second window may be the smallest delay that allows higher areas of the brain to account for the delays created in the first stages of the system while still operating near the border of the present. This window of delay means that awareness is postdictive, incorporating data from a window of time after an event and delivering a retrospective interpretation of what happened."

Monday, September 23, 2013

Depressive realism - better time keeping

We’ve known for quite a while that depressed people appear to have a more realistic perception of their importance, reputation, locus of control, and abilities than those who are not depressed. In fact this depressive realism was something the French philosopher Voltaire dealt with as early as 1759 in his novel Candide: Or, Optimism.

New research led by the University of Hertfordshire shows that depressed people are more accurate when it comes to time estimation than their happier peers.

In the study, volunteers gave verbal estimates of the length of different time intervals of between two and sixty-five seconds and they also produced their own time intervals. For non-depressed people, their verbal time interval estimations were too high; while their own production of times in the same range were too low. In contrast, the mildly-depressed people were accurate in both their verbal time estimates and also their own production times.

It’s said that the findings may help to shed light on how people with depression can be treated. People with depression are often encouraged to check themselves against reality, but maybe this timing skill can help in the treatment of mildly-depressed people. These findings may also link to successful mindfulness based treatments for depression which focus on encouraging present moment awareness.

Wednesday, September 18, 2013

Competing models of time perception

Anyone that knows me will know my fascination with time. Not how we go about measuring time but time it self. Here there are 2 equally important paths of endeavor. One is that of a global scale and involves the very nature of the universe; Space-Time continuum and General Relativity.  The second is equally baffling – how does the brain code time.

There are multiple competing models of time perception with no real consensus. For example we know that the Suprachiasmatic nucleus uses environmental cues, most importantly light, to determine the time of day and year thus coordinating circadian rhythms. This however is more about tracking time and less about perception of time. Also, this may not be the structure that links events to time – i.e. history.

According to a recent MIT study groups of neurons in the primate brain code time with extreme precision. Institute Professor Ann Graybiel says “All you do is time stamp everything, and then recalling events is easy: you go back and look through your time stamps until you see which ones are correlated with the event,"

Neuroscientist Paul King of the Redwood Center for Theoretical Neuroscience at UC Berkeley explains fast time interval estimation (sub-second) to be important for timing complex behavior and playing musical instruments. Slow time interval estimation may be important for planning the day, although daylight and hunger can provide cues. Intervals greater than a day may rely on observing the repetition of day-night cycles and seasonal changes.

The above diagram shows the accuracy of time interval estimation for humans and other animals, along with proposed neural mechanisms for each time scale. Slow time scales (hours) are at the top and fast scales (milliseconds) are at the bottom. It’s a fascinating model.

Thursday, September 12, 2013

Let's not under estimate human ingenuity

I, like many, am interested in the latest, newest and shiniest new gadgets and in particular smartphones (read iPhones). So I’ve been eagerly awaiting the most recent launch of the iPhone 5S and the more fun-bound iPhone 5C. With every new phone comes the usual swag of analytics. Value for money, could the vendor have packed more features, has this leap-frogged incremental advances, and more.

What really caught my attention this time however was the number of analysts and journalists seeing the new iPhone batch as not really constituting a quantum leap in innovation – and some claim that It could be that there just isn't much more you can do to jazz up a smartphone. In which case, we've reached "peak smartphone".

This kinda think is a little shortsighted isn’t it? After all, wasn’t it Thomas Watson (chairman and CEO of IBM who oversaw that company's growth into an international force from 1914 to 1956) who was supposed to have made the remark in 1943, "I think there is a world market for maybe five computers".