Behavioral+Genetics+Lab
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Animal Cyborg: Behavioral Control by 'Toy' Craving Circuit
Children love to get toys from parents for their birthday present. This craving toward items also involves object hoarding disorders and shopping addiction. However, the biological meaning of why the brain pursues objects or items has remained unknown. Part of the answer may lie with a neural circuit in the hypothalamus associated with “object craving,” says neuroscientist Daesoo Kim from the Department of Biological Sciences at KAIST.
His research team found that some neurons in the hypothalamus are activated during playing with toys in mice. Thanks to optogenetics, they proved that these neurons in the hypothalamus actually governs obsessive behavior toward non-food objects in mice.
“When we stimulate a neuron in the hypothalamus of mice, they anxiously chased target objects. We found evidence that the neural circuits in the medial preoptic area (MPA) modulate “object craving,” the appetite for possessing objects” said Professor Kim.
Researchers also proved that the MPA circuit facilitate hunting behavior in response to crickets, a natural prey to mice, showing the role of this circuit for catching prey. Further, the MPA nerves send excitatory signals to the periaqueductal gray (PAG), located around the cerebral aqueduct, to create such behavior. The team named this circuit the ‘MPA-PAG’ circuit.
The team showed that they could control mammalian behavior for the first time with this scheme of MPA-Induced Drive Assisted Steering (MIDAS), in which a mouse chase the target objects in the front of head during stimulation of the MPA-PAG circuit. MIDAS allows mice to overcome obstacles to move in a desired path using optogenetics.
(Professor Daesoo Kim)
Professor Kim, who teamed up with Professor Phill Seung Lee in the Department of Mechanical Engineering, explained the significance of the research, “This study provides evidence to treat brain disorders such as compulsive hoarding and kleptomania. It also contributes to the development of technology to control the behavior of animals and humans using strong innate motivation, and thus could impact neuro-economics, defense, and disaster relief.”
He said the team would like to complete the neural circuit map governing behaviors of possession and hunting in the near future by exploring correlations with other neural behaviors controlling possessing and hunting activities.
This research was funded by the Samsung Science and Technology Foundation and published in Nature Neuroscience in March 2018.
(Figure 1: Schematics showing possessive behavior induced by the MPA neural circuit)
(Figure 2: Schematics of the MIDAS system that controls mammals behavior using the desire to possess. A MIDAS mouse is following the bait object controlled wirelessly.)
2018.04.23 View 8585 -
Unlocking the Keys to Parkinson's Disease
A KAIST research team has identified a new mechanism that causes the hallmark symptoms of Parkinson’s disease, namely tremors, rigidity, and loss of voluntary movement.
The discovery, made in collaboration with Nanyang Technological University in Singapore, presents a new perspective to three decades of conventional wisdom in Parkinson’s disease research. It also opens up new avenues that can help alleviate the motor problems suffered by patients of the disease, which reportedly number more than 10 million worldwide. The research was published in Neuron on August 30.
The research team was led by Professor Daesoo Kim from the Department of Biological Sciences at KAIST and Professor George Augustine from the Lee Kong Chian School of Medicine at NTU. Dr. Jeongjin Kim, a former postdoctoral fellow at KAIST who now works at the Korea Institute of Science and Technology (KIST), is the lead author.
It is known that Parkinson’s disease is caused by a lack of dopamine, a chemical in the brain that transmits neural signals. However, it remains unknown how the disease causes the motor
Smooth, voluntary movements, such as reaching for a cup of coffee, are controlled by the basal ganglia, which issue instructions via neurons (nerve cells that process and transmit information in the brain) in the thalamus to the cortex. These instructions come in two types: one that triggers a response (excitatory signals) and the other that suppresses a response (inhibitory signals). Proper balance between the two controls movement.
A low level of dopamine causes the basal ganglia to severely inhibit target neurons in the thalamus, called an inhibition. Scientists have long assumed that this stronger inhibition causes the motor problems of Parkinson’s disease patients.
To test this assumption, the research team used optogenetic technology in an animal model to study the effects of this increased inhibition of the thalamus and ultimately movement. Optogenetics is the use of light to control the activity of specific types of neurons within the brain.
They found that when signals from the basal ganglia are more strongly activated by light, the target neurons in the thalamus paradoxically became hyperactive. Called rebound excitation, this hyperactivity produced abnormal muscular stiffness and tremor. Such motor problems are very similar to the symptoms of Parkinson’s disease patients. When this hyperactivity of thalamic neurons is suppressed by light, mice show normal movments without Parkinson’s disease symptoms. Reducing the levels of activity back to normal caused the motor symptoms to stop, proving that the hyperactivity caused the motor problems experienced by Parkinson’s disease patients.
Professor Kim at KAIST said, “This study overturns three decades of consensus on the provenance of Parkinsonian symptoms.” The lead author, Dr Jeongjin Kim said, “The therapeutic implications of this study for the treatment of Parkinsonian symptoms are profound. It may soon become possible to remedy movement disorders without using L-DOPA, a pre-cursor to dopamine.”
Professor Augustine at NTU added, “Our findings are a breakthrough, both for understanding how the brain normally controls the movement of our body and how this control goes awry during Parkinson’s disease and related dopamine-deficiency disorders.”
The study took five years to complete, and includes researchers from the Department of Bio & Brain Engineering at KAIST.
The research team will move forward by investigating how hyperactivity in neurons in the thalamus leads to abnormal movement, as well as developing therapeutic strategies for the disease by targeting this neural mechanism.
Figure abstract: Inhibitory inputs from the basal ganglia inhibit thalamic neurons (upper). In low-dopamine states, like PD, rebound firing follows inhibition and causes movement disorders (middle). The inhibition of rebound firing alleviates PD-like symptoms in a mouse model of PD.
2017.09.22 View 9468 -
Discovery of New Therapeutic Targets for Alzheimer's Disease
A Korean research team headed by Professor Dae-Soo Kim of Biological Sciences at KAIST and Dr. Chang-Jun Lee from the Korea Institute of Science and Technology (KIST) successfully identified that reactive astrocytes, commonly observed in brains affected by Alzheimer’s disease, produce abnormal amounts of inhibitory neurotransmitter gamma-Aminobutyric acid (GABA) in reaction to the enzyme Monoamine oxidase B (Mao-B) and release GABA through the Bestrophin-1 channel to suppress the normal signal transmission of brain nerve cells.
By suppressing the GABA production or release from reactive astrocytes, the research team was able to restore the model mice's memory and learning impairment caused by Alzheimer’s disease. This discovery will allow the development of new drugs to treat Alzheimer’s and other related diseases.
The research result was published in the June 29, 2014 edition of Nature Medicine (Title: GABA from Reactive Astrocytes Impairs Memory in Mouse Models of Alzheimer’s Disease).
For details, please read the article below:
Technology News, July 10, 2014
"Discovery of New Drug Targets for Memory Impairment in Alzheimer’s Disease"
http://technews.tmcnet.com/news/2014/07/10/7917811.htm
2014.07.16 View 8336 -
Novel material that prevents health decline with age found
Professor Kim Dae Soo (Department of Biological Science), his research team, the Choong Nam University Medicine School, and various companies conducted collaborative research succeeded in developing a novel material that prevents health decline with age. The result was published in PLoS One Journal with the title “Beta-lapachone, a modulator of NAD metabolism, prevents health declines in aged mice”.
Longevity and health can be obtained with reducing consumption of food and aerobic exercise.
Professor Kim’s team focused on the fact that reduced consumption of food and aerobic exercise increase the coenzyme (NAD+) which suppresses the aging of cells. The research team discovered that by activating NQO1 enzyme with Beta-lapachone, the amount of NAD+ in the body increases even without reduction of food consumption or aerobic exercise.
Even consumption of Beta-lapachone by aging mice caused an improved on the brain and exercise ability of the mice. It is expected that commercialization of Beta-lapachone will be possible as it is a chemical that is commonly found in herbs used in both the orient and the oxidant.
2012.12.21 View 6958