Adult White Killer Whale Spotted in the Wild for the First Time

April 24, 2012

Biology

There have been sightings of white whales sporadically over the last few decades, but the only white killer whales (Orcinus orca) were young, including one with a rare genetic condition that died in a Canadian aquarium in 1972.
A group of Russian scientists and students on a research cruise off Kamchatka made the sightings of an adult O. orca. The only two other white orcas seen in Russia were young, but this time, researchers are sure it’s an adult they’ve spotted. The dorsal fin measured two meters in height, implying that it’s at least 16 years old. The fin was somewhat ragged, so it could even be older.

Male killer whales can live up to 50 or 60 years, though 30 is the median life expectancy. They mature at the age of 15. The researchers have called him Iceberg and he seems fully socialized with this pod. The cause of the unusual pigmentation is not yet known. It could be the Chediak-Higashi syndrome, but researchers hope to get a closer look at Iceberg to see his eye color.

O. orca have a complex social structure, including matrilineal family clans, pods consisting of several families, and much larger super-pods.

Crowdsourcing Experiment Aims To Decode Whale Song

November 30, 2011

Science

The race is on to decode whale song and you can help. A global crowdsourcing experiment may finally be what is needed to unlock the mystery of just what whale song is all about.
Any “Citizen Scientists” who are interested can study about 15,000 recordings of calls by pilot whales and killer whales around the planet. Hopefully we can learn some new phrases, meanings and dialects. The Whale Project was launched today by Scientific American and the online citizen science organization The Zooniverse.
If you are interested, just visit whale.fm where you will be able to study and then compare sound wave patterns of calls made by whales in different pods and families around the world via spectrogram. The idea is to identify identical or similar sound wave patterns, and don’t worry, you will be able to play back each sound as you study it. Each sound recording is linked to a specific location in the sea, so scientists know which calls come from which specific families of whales and where.
Why not just use computers? It turns out that people are better at spotting similarities in complex spectrograms. The human brain excels at comparing images. Every matched group of sounds will be compared with the whales’ location and activities that the whales were involved in. They are hoping to discover a dialect at the least and if they get very lucky, perhaps different kinds of messages.

Neuroscientists Decode Correlation Between Sound and Brain Activity

January 31, 2012

Biology

An X-ray CT scan of the head of one of the volunteers, showing electrodes distributed over the brain’s temporal lobe, where sounds are processed.

UC Berkeley neuroscientists are hoping to be able to hear the unsaid words of patients in the near future. While conducting their research, they were able to decode the electrical activity in the brain’s temporal lobe as a person listens to normal conversation, which in turn allowed them to predict the words the person had heard solely from the temporal lobe activity. By understanding the correlation between sound and brain activity, neuroscientists hope to use this technology to help people that have damage to their speech mechanisms.
BERKELEY — Neuroscientists may one day be able to hear the imagined speech of a patient unable to speak due to stroke or paralysis, according to University of California, Berkeley, researchers.
These scientists have succeeded in decoding electrical activity in the brain’s temporal lobe – the seat of the auditory system – as a person listens to normal conversation. Based on this correlation between sound and brain activity, they then were able to predict the words the person had heard solely from the temporal lobe activity.
“This research is based on sounds a person actually hears, but to use it for reconstructing imagined conversations, these principles would have to apply to someone’s internal verbalizations,” cautioned first author Brian N. Pasley, a post-doctoral researcher in the center. “There is some evidence that hearing the sound and imagining the sound activate similar areas of the brain. If you can understand the relationship well enough between the brain recordings and sound, you could either synthesize the actual sound a person is thinking, or just write out the words with a type of interface device.”
“This is huge for patients who have damage to their speech mechanisms because of a stroke or Lou Gehrig’s disease and can’t speak,” said co-author Robert Knight, a UC Berkeley professor of psychology and neuroscience. “If you could eventually reconstruct imagined conversations from brain activity, thousands of people could benefit.”
In addition to the potential for expanding the communication ability of the severely disabled, he noted, the research also “is telling us a lot about how the brain in normal people represents and processes speech sounds.”
Pasley and his colleagues at UC Berkeley, UC San Francisco, University of Maryland and The Johns Hopkins University report their findings Jan. 31 in the open-access journal PLoS Biology.
Help from epilepsy patients
They enlisted the help of people undergoing brain surgery to determine the location of intractable seizures so that the area can be removed in a second surgery. Neurosurgeons typically cut a hole in the skull and safely place electrodes on the brain surface or cortex – in this case, up to 256 electrodes covering the temporal lobe – to record activity over a period of a week to pinpoint the seizures. For this study, 15 neurosurgical patients volunteered to participate.
Pasley visited each person in the hospital to record the brain activity detected by the electrodes as they heard 5-10 minutes of conversation. Pasley used this data to reconstruct and play back the sounds the patients heard. He was able to do this because there is evidence that the brain breaks down sound into its component acoustic frequencies – for example, between a low of about 1 Hertz (cycles per second) to a high of about 8,000 Hertz –that are important for speech sounds.
Pasley tested two different computational models to match spoken sounds to the pattern of activity in the electrodes. The patients then heard a single word, and Pasley used the models to predict the word based on electrode recordings.
“We are looking at which cortical sites are increasing activity at particular acoustic frequencies, and from that, we map back to the sound,” Pasley said. He compared the technique to a pianist who knows the sounds of the keys so well that she can look at the keys another pianist is playing in a sound-proof room and “hear” the music, much as Ludwig van Beethoven was able to “hear” his compositions despite being deaf.
The better of the two methods was able to reproduce a sound close enough to the original word for Pasley and his fellow researchers to correctly guess the word.
“We think we would be more accurate with an hour of listening and recording and then repeating the word many times,” Pasley said. But because any realistic device would need to accurately identify words heard the first time, he decided to test the models using only a single trial.
“This research is a major step toward understanding what features of speech are represented in the human brain” Knight said. “Brian’s analysis can reproduce the sound the patient heard, and you can actually recognize the word, although not at a perfect level.”
Knight predicts that this success can be extended to imagined, internal verbalizations, because scientific studies have shown that when people are asked to imagine speaking a word, similar brain regions are activated as when the person actually utters the word.
“With neuroprosthetics, people have shown that it’s possible to control movement with brain activity,” Knight said. “But that work, while not easy, is relatively simple compared to reconstructing language. This experiment takes that earlier work to a whole new level.”
Based on earlier work with ferrets
The current research builds on work by other researchers about how animals encode sounds in the brain’s auditory cortex. In fact, some researchers, including the study’s coauthors at the University of Maryland, have been able to guess the words ferrets were read by scientists based on recordings from the brain, even though the ferrets were unable to understand the words.
The ultimate goal of the UC Berkeley study was to explore how the human brain encodes speech and determine which aspects of speech are most important for understanding.
“At some point, the brain has to extract away all that auditory information and just map it onto a word, since we can understand speech and words regardless of how they sound,” Pasley said. “The big question is, What is the most meaningful unit of speech? A syllable, a phone, a phoneme? We can test these hypotheses using the data we get from these recordings.”
Coauthors of the study are electrical engineers Stephen V. David, Nima Mesgarani and Shihab A. Shamma of the University of Maryland; Adeen Flinker of UC Berkeley’s Helen Wills Neuroscience Institute; and neurologist Nathan E. Crone of The Johns Hopkins University in Baltimore, Md. The work was done principally in the labs of Robert Knight at UC Berkeley and Edward Chang, a neurosurgeon at UCSF.
Source: Robert Sanders, UC Berkeley
Image: Adeen Flinker, UC Berkeley
Chang and Knight are members of the Center for Neural Engineering and Prostheses, a joint UC Berkeley/UCSF group focused on using brain activity to develop neural prostheses for motor and speech disorders in disabling neurological disorders.

Neuroscientists Predict Which Parts of the Fusiform Gyrus are Face-Selective

January 7, 2012

Science

Neuroscientists know a lot about the functionality of our brain cells and recently they furthered that knowledge with a new discovery. By tracing the interaction between the fusiform gyrus, the brain region responsible for face recognition, and using diffusion-weighted imaging, researchers may be able to better understand face-recognition impairments.
For more than a decade, neuroscientists have known that many of the cells in a brain region called the fusiform gyrus specialize in recognizing faces. However, those cells don’t act alone: They need to communicate with several other parts of the brain. By tracing those connections, MIT neuroscientists have now shown that they can accurately predict which parts of the fusiform gyrus are face-selective.
The study, which appeared in the Dec. 25 issue of the journal Nature Neuroscience, is the first to link a brain region’s connectivity with its function. No two people have the exact same fusiform gyrus structure, but using connectivity patterns, the researchers can now accurately predict which parts of an individual’s fusiform gyrus are involved in face recognition.
This work goes a step beyond previous studies that have used magnetic resonance imaging (MRI) to locate the regions that are involved in particular functions. “Rather than just mapping the brain, what we’re doing now is adding on to that a description of function with respect to connectivity,” says David Osher, a lead author of the paper and a graduate student in the lab of John Gabrieli, the Grover Hermann Professor of Health Sciences and Technology and Cognitive Neuroscience and a member of MIT’s McGovern Institute for Brain Research.
Using this approach, scientists may be able to learn more about the face-recognition impairments often seen in autism and prosopagnosia, a disorder often caused by stroke. This method could also be used to determine relationships between structure and function in other parts of the brain.
To map the brain’s connectivity patterns, the researchers used a technique called diffusion-weighted imaging, which is based on MRI. A magnetic field applied to the brain of the person in the scanner causes water in the brain to flow in the same direction. However, wherever there are axons — the long cellular extensions that connect a neuron to other brain regions — water is forced to flow along the axon, rather than crossing it. This is because axons are coated in a fatty material called myelin, which is impervious to water.
By applying the magnetic field in many different directions and observing which way the water flows, the researchers can identify the locations of axons and determine which brain regions they are connecting.
“For every measurable unit of the brain at this level, we have a description of how it connects with every other region, and with what strength it connects with every other region,” says Zeynep Saygin, a lead author of the paper and a graduate student who is advised by Gabrieli and Rebecca Saxe, senior author of the paper and associate professor of brain and cognitive sciences.
Gabrieli is also an author of the paper, along with Kami Koldewyn, a postdoc in MIT professor Nancy Kanwisher’s lab, and Gretchen Reynolds, a former technical assistant in Gabrieli’s lab.
Making connections
The researchers found that certain patches of the fusiform gyrus were strongly connected to brain regions also known to be involved in face recognition, including the superior and inferior temporal cortices. Those fusiform gyrus patches were also most active when the subjects were performing face-recognition tasks.
Based on the results in one group of subjects, the researchers created a model that predicts function in the fusiform gyrus based solely on the observed connectivity patterns. In a second group of subjects, they found that the model successfully predicted which patches of the fusiform gyrus would respond to faces.
“This is the first time we’ve had direct evidence of this relationship between function and connectivity, even though you certainly would have assumed that was going to be true,” says Saxe, who is also an associate member of the McGovern Institute. “One thing this paper does is demonstrate that the tools we have are sufficient to see something that we strongly believed had to be there, but that we didn’t know we’d be able to see.”
The other regions connected to the fusiform gyrus are believed to be involved in higher-level visual processing. One surprise was that some parts of the fusiform gyrus connect to a part of the brain called the cerebellar cortex, which is not thought to be part of the traditional vision-processing pathway. That area has not been studied very thoroughly, but a few studies have suggested that it might have a role in face recognition, Osher says.
Now that the researchers have an accurate model to predict function of fusiform gyrus cells based solely on their connectivity, they could use the model to study the brains of patients, such as severely autistic children, who can’t lie down in an MRI scanner long enough to participate in a series of face-recognition tasks. That is one of the most important aspects of the study, says Michael Beauchamp, an associate professor of neurobiology at the University of Texas Medical School.
“Functional MRI is the best tool we have for looking at human brain function, but it’s not suitable for all patient groups, especially children or older people with cognitive disabilities,” says Beauchamp, who was not involved in this study.
The MIT researchers are now expanding their connectivity studies into other brain regions and other visual functions, such as recognizing objects and scenes, as well as faces. They hope that such studies will also help to reveal some of the mechanisms of how information is processed at each point as it flows through the brain.

Brain Oscillations Reveal We Experience the World in Rapid Snapshots

May 14, 2012

Biology

Neuroscientists from the University of Glasgow have demonstrated that our brains experience the world in discrete snapshots determined by the cycles of brain rhythms. While studying a brain rhythm associated with visual cortex, they used a “simple trick” to affect and “reset” the oscillations of this rhythm.
It has long been suspected that humans do not experience the world continuously, but rather in rapid snapshots.
Now, researchers at the University of Glasgow have demonstrated this is indeed the case. Just as the body goes through a 24-hour sleep-wake cycle controlled by a circadian clock, brain function undergoes such cyclic activity – albeit at a much faster rate.
Professor Gregor Thut of the Institute of Neuroscience and Psychology, said: “Rhythms are intrinsic to biological systems. The circadian rhythm, with its very slow periodicity of sleep and wake cycles every 24 hours has an obvious, periodic effect on bodily functions.
“Brain oscillations – the recurrent neural activity that we see in the brain – also show periodicity but cycle at much faster speeds. What we wanted to know was whether brain function was affected in a cyclic manner by these rapid oscillations.”
The researchers studied a prominent brain rhythm associated with visual cortex functioning that cycles at a rate of 10 times per second (10Hz).
They used a ‘simple trick’ to affect the oscillations of this rhythm which was presenting a brief sound to ‘reset’ the oscillation.
Testing subsequent visual perception, by using transcranial magnetic stimulation of visual cortex, revealed a cyclic pattern at the very rapid rate of brain oscillations, in time with the underlying brainwaves.
Prof Thut said: “Rhythmicity therefore is indeed omnipresent not only in brain activity but also brain function. For perception, this means that despite experiencing the world as a continuum, we do not sample our world continuously but in discrete snapshots determined by the cycles of brain rhythms.”
The research, ‘Sounds reset rhythms of visual cortex and corresponding human visual perception’ is published in the journal Current Biology.