Neuroscience : Modern Research and Development

Neuroscience : Modern Research and Development

   

BrdU (red), a marker of DNA replication, highlights neurogenesis in the subgranular zone of hippocampal dentate gyrus. Fragment of an illustration from Faiz et al.,

Neurogenesis (birth of neurons):

 Is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of mammals: the hippocampus and the subventricular zone. Studies have indicated that hormones, such as testosterone in vertebrates and ecdysone in invertebrates, have an influence on the rate of neurogenesis.

What began with the song of a small bird has changed an entire paradigm in neuroscience. About 20 years ago, research on the ability of adult songbirds to learn new songs showed that their brains created new cells and that these neurons helped them form memories of the new songs. This opened up debate on whether the same process occurred in humans. Subsequent research confirmed human neurogenesis, and now questions revolve around the extent that neurogenesis occurs, where it occurs, and the function new neurons perform in the working brain.

Role in learning

The functional relevance of adult neurogenesis is uncertain,but there is some evidence that hippocampal adult neurogenesis is important for learning and memory. Multiple mechanisms for the relationship between increased neurogenesis and improved cognition have been suggested, including computational theories to demonstrate that new neurons increase memory capacity,reduce interference between memories, or add information about time to memories.Experiments aimed at ablating neurogenesis have proven inconclusive, but several studies have proposed neurogenic-dependence in some types of learning, and others seeing no effect. Studies have demonstrated that the act of learning itself is associated with increased neuronal survival. However, the overall findings that adult neurogenesis is important for any kind of learning are equivocal.

Adult Neurogenesis

For more than a century, medical science firmly believed that our brain could not repair itself and that we were born with all the brain cells we would ever have. That belief has changed. Over the last 20 years, research has shown that neurogenesis, the creation of new brain cells, actually occurs in the adult human. Currently, work is shifting to find out where neurogenesis happens, how it happens, why it happens, and, more importantly, how it might help the brain heal itself.

Although scientists still debate the extent and purpose of neurogenesis in the adult brain, research has identified certain areas of the brain where it is most evident. These areas include the hippocampus, caudate nucleus, and olfactory bulb.

Adult neurogenesis in the dentate gyrus. (A) Neural stem cells proliferate ...

How Brain-computer Interfaces Work:

A brain–computer interface (BCI), often called a mind-machine interface (MMI), or sometimes called a direct neural interface or a brain–machine interface (BMI), is a direct communication pathway between the brain and an external device. BCIs are often directed at assisting, augmenting, or repairing human cognitive or sensory-motor functions.

brain-computer-interface

As the power of modern computers grows alongside our understanding of the human brain, we move ever closer to making some pretty spectacular science fiction into reality. Imagine transmitting signals directly to someone's brain that would allow them to see, hear or feel specific sensory inputs. Consider the potential to manipulate computers or machinery with nothing more than a thought. It isn't about convenience -- for severely disabled people, development of a brain-computer interface (BCI) could be the most important technological breakthrough in decades. In this article, we'll learn all about how BCIs work, their limitations and where they could be headed in the future.

The Electric Brain

The reason a BCI works at all is because of the way our brains function. Our brains are filled with neurons, individual nerve cells connected to one another by dendrites and axons. Every time we think, move, feel or remember something, our neurons are at work. That work is carried out by small electric signals that zip from neuron to neuron as fast as 250 mph [source: Walker]. The signals are generated by differences in electric potential carried by ions on the membrane of each neuron.

 Dr. Jose Principe Computional NeuroEngineering Lab university of florida.

Control BMIs

In the last decade, emerging developments in microchip design, signal processing algorithms, computers, sensors, and robotics are coalescing into a new technology devoted to creating a different type of BMI, which translates brain activity in a specific area of the motor cortex into the corresponding movement of some device in two-dimensional (2D) or three-dimensional (3D) space – so-called trajectory control BMIs. For example, electrodes placed in the part of the brain that controls the right hand can provide real-time control of cursor movements on a computer screen, as if a mouse is being used. These BMIs can be thought of as intelligent agents that translate intention of movement from the biological “wetware” to the firmware of a robotic actuator.

Connecting Your Brain to the Game (EEG-Based):

Emotiv Systems, an electronic-game company from San Francisco, wants people to play with the power of the mind. Starting tomorrow, video-game makers will be able to buy Emotiv's electro-encephalograph (EEG) caps and software developer's tool kits so that they can build games that use the electrical signals from a player's brain to control the on-screen action

Emotiv’s electro-encephalograph cap: Each small circle on the cap is a sensor that measures the electrical activity at the scalp generated by brain activity and facial movements. The information is wirelessly transmitted to a computer, where software uses it to let people mentally interact with video games.

Credit: Lewis PR and Emotiv Systems

Japanese scientists create dream recording machine:

The institute is called ATR, and based in Kyoto, Japan. The technology is more low-tech than you’d think: a subject is placed in an MRI machine and their visual cortex is scanned while they look at still images representing simple geometrical shapes in monochrome. The system then attempts to reproduce exactly what the subject sees.

Additionally, ATR says the machine is limited to reproducing images that have not been shown to subjects before. That implies that the MRI machine is actually matching electrical patterns on the visual cortex with a finite library of pre-programmed shapes… although the next step, they say, is to have the system recreate images that have not been shown to the subjects before.

Researchers from UC Berkeley in California have

found a way to reconstruct videos from viewers’ brain activity – a feat that might one day offer a glimpse into our dreams, memories and even fantasies.

“This is a major leap toward reconstructing internal imagery,” said Jack Gallant, professor of psychology. “We are opening a window into the movies in our minds.”

Gallant’s worked with study subjects, watching YouTube videos inside a magnetic resonance imaging (MRI) machine for several hours at a time. The team then used the brain imaging data to develop a computer model that matched features of the videos — like colors, shapes and movements — with patterns of brain activity.

“If you can decode movies people saw, you might be able to decode things in the brain that are movie-like but have no real-world analog, like dreams,” Gallant said.

brain_imaging_video-

Mirror neuron:

A mirror neuron is a neuron that fires both when an animal acts and when the animal observes the same action performed by another.Thus, the neuron "mirrors" the behaviour of the other, as though the observer were itself acting. Such neurons have been directly observed in primate and other species including birds. In humans, brain activity consistent with that of mirror neurons has been found in the premotor cortex, the supplementary motor area, the primary somatosensory cortex and the inferior parietal cortex.

The first animal in which mirror neurons have been studied individually is the macaque monkey. In these monkeys, mirror neurons are found in the inferior frontal gyrus  and the inferior parietal lobule.

Mirror neurons are believed to mediate the understanding of other animals' behaviour. For example, a mirror neuron which fires when the monkey rips a piece of paper would also fire when the monkey sees a person rip paper, or hears paper ripping (without visual cues). These properties have led researchers to believe that mirror neurons encode abstract concepts of actions like 'ripping paper', whether the action is performed by the monkey or another animal.

Diagram of the brain, showing the locations of the frontal and parietal lobes of the cerebrum, viewed from the left. The inferior frontal lobe is the lower part of the blue area, and the superior parietal lobe is the upper part of the yellow area.

MIRROR NEURONS AND THE BRAIN IN THE VAT [1.10.06]

by V.S. Ramachandran

Neonatal (newborn) macaque imitating facial expressions.

 V.S. Ramachandran

Six years ago, Edge published a now-famous essay by neuroscientist V.S. Ramachandran ( (known to friends and colleagues as "Rama"), entitled "Mirror Neurons and imitation learning as the driving force behind "the great leap forward" in human evolution" . This was the first time that many in the Edge community heard of mirror neurons which were discovered by Iaccomo Rizzolati of the University of Parma in 1995. In his essay, Rama made the startling prediction that mirror neurons would do for psychology what DNA did for biology by providing a unifying framework and help explain a host of mental abilities that have hitherto remained mysterious and inaccessible to experiments. He further suggested "that the emergence of a sophisticated mirror neuron system set the stage for the emergence, in early hominids, of a number of uniquely human abilities such as proto-language (facilitated by mapping phonemes on to lip and tongue movements), empathy, 'theory of other minds', and the ability to 'adopt another's point of view'.

In the past few years, mirror neurons have come into their own as the next big thing in neuroscience.

Phantom limb:

A phantom limb is the sensation that an amputated or missing limb (even an organ, like the appendix) is still attached to the body and is moving appropriately with other body parts. Approximately 60 to 80% of individuals with an amputation experience phantom sensations in their amputated limb, and the majority of the sensations are painful. Phantom sensations may also occur after the removal of body parts other than the limbs, e.g. after amputation of the breast, extraction of a tooth (phantom tooth pain) or removal of an eye (phantom eye syndrome). The missing limb often feels shorter and may feel as if it is in a distorted and painful position. Occasionally, the pain can be made worse by stress, anxiety, and weather changes. Phantom limb pain is usually intermittent. The frequency and intensity of attacks usually declines with time.

Until recently, the dominant theory for cause of phantom limbs was irritation in the severed nerve endings (called "neuromas"). When a limb is amputated, many severed nerve endings are terminated at the residual limb. These nerve endings can become inflamed, and were thought to send anomalous signals to the brain. These signals, being functionally nonsense, were thought to be interpreted by the brain as pain.

The fact that the representation of the face lies adjacent to the representation of the hand and arm in the cortical homunculus is crucial to explaining the origin of phantom limbs.

The Penfield hommunculus notice that the hand area is bordered below by the face and above by the upper arm and shoulder-the two region were reference fielda are usually found in arm amputees.

By the late 1980s, Ronald Melzack had recognized that the peripheral neuroma account could not be correct. In his 1989 paper,"Phantom Limbs, The Self And The Brain" Melzack proposed the theory of the "neuromatrix." According to Melzack the experience of the body is created by a wide network of interconnecting neural structures. In 1991, Tim Pons and colleagues at the National Institutes of Health (NIH) showed that the primary somatosensory cortex undergoes substantial reorganization after the loss of sensory input. Hearing about these results, Vilayanur S. Ramachandran theorized that phantom limb sensations could be due to this reorganization in the somatosensory cortex, which is located in the postcentral gyrus, and which receives input from the limbs and body. Ramachandran and colleagues illustrated this theory by showing that stroking different parts of the face led to perceptions of being touched on different parts of the missing limb.

The fact that the representation of the face lies adjacent to the representation of the hand and arm in the cortical homunculus is crucial to explaining the origin of phantom limbs.

The Penfield hommunculus notice that the hand area is bordered below by the face and above by the upper arm and shoulder-the two region were reference fielda are usually found in arm amputees.

Knight`s Dream

Dream Research:

Planting dreams for research

Note to students: Take a power nap before the final exam and dream about the class material. The approach could lead to significantly higher test scores than the results achieved by non-napping and non-dreaming classmates, according to researchers at Harvard Medical School.

In a study, the researchers taught students to navigate a three-dimensional maze and then let some of the students take a two-hour nap before a test on the maze. Though not everyone who took a nap dreamed of the maze, those who did performed better on the test than the non-maze dreamers and the students who stayed awake and kept rehearsing the maze.

"We think that the dreams are a marker that the brain is working on the same problem at many levels," study author Robert Stickgold said. "The dreams might reflect the brain's attempt to find associations for the memories that could make them more useful in the future."

Dreams are reservoirs of ideas

Stephen Vaughan

For extraction to be a viable means of employment for Cobb and his crew, the dreams themselves must offer up something worth stealing — personal ideas. “That’s completely on the money,” said Jayne Gackenbach, a dream researcher at Grant MacEwan University in Edmonton, Canada.

In general terms, the dreaming mind’s idea-generation process is largely autobiographical. An experience during the day gets incorporated, often in a seemingly odd way, with a dream, leading the dreamer to make an association that is almost always personal.

She cited a personal example: Her mother had a dream about her father, who had passed away not long before. He appeared at the foot of her mother's bed, dressed in a gray suit. "The association she made to that was before she got overweight, she loved to wear gray suits and she looked so good," Gackenbach said. "[That's] something I would have no way of knowing."

Planting dreams far from impossible

Warner Bros. Picture

Cobb's job in “Inception” is to do the opposite of extraction: He is given the task of planting a dream in the mind of Robert Fisher (Cillian Murphy). Gackenbach said this is something that people and dream researchers do on a regular basis, though not necessarily with so much Hollywood glitz.

For example, a person considering a job choice might seek guidance from their deep subconscious. To do so, Gackenbach said, the first step is to clear the mind of excess dream material by writing down anything emotional that occurred in the last few days. This relieves the mind of needing to process that information while asleep.

"Then, as you go to sleep, you ask the question that you want answered in your dream," she said. "And, of course, it is important to write the dream down to see if there is some information. Sometimes it will be very direct, sometimes it will be obfuscated."