Navigation Links
Streamlining brain signals for speed and efficacy
Date:10/22/2008

LA JOLLA, CA Life exists at the edge of chaos, where small changes can have striking and unanticipated effects, and major stimuli may go unheard. But there is no space for ambiguity when the brain needs to transform head motion into precise eye, head, and body movements that rapidly stabilize our posture and gaze; otherwise, we would stumble helplessly through the world, and our vision would resemble an undecipherable blur.

In their latest study, published in the current issue of the journal Neuron, researchers at the Salk Institute for Biological Studies explain how the vestibular-ocular reflex, which keeps us and the world around us stable, achieves the accuracy it is famous for. Unlike most signals in the brain, whose transmission is frequency-dependent, signals from the vestibular system of the inner ear, which detects motion, are relayed in a linear fashion no matter how fast the neurons are firing.

"Most of what we know about signal transmission between neurons comes from studying special cortical or hippocampal neurons, but many vital functions, such as balance and breathing, are controlled by neurons in the brain stem, which, as we discovered, work very differently," says Howard Hughes Medical Institute investigator Sascha du Lac, Ph.D., an associate professor in the Systems Neurobiology Laboratory. "Pursuing the mechanisms that control neurons in the brain stem is important for developing new classes of biotherapeutic agents."

Du Lac and her team focus on a simple type of learning: How does the brain learn to stabilize an image on the retina and use eye movement to compensate for a moving head? This so-called vestibular-ocular reflex, or VOR, needs to be fast; for clear vision, head movements must be compensated for almost immediately. To achieve the necessary speed, the VOR-circuit involves only three types of neurons: sensory neurons, which detect head movement; motor neurons, directing eye muscles to relax or contract; and so-called vestibular nucleus neurons in the brainstem that link the two.

While the brevity of this circuit keeps reflex times short, it was less clear what qualities of the circuit ensure that eye velocity is precisely matched to head velocity. Since the VOR operates accurately no matter how fast we move our head, scientists long expected that the signal transmission at the synapsesspecialized points of contact between nerve cellsthat connect the sensory onto the vestibular nucleus neurons would be linear.

However, transmission at most synapses is non-linear. Brain cells signal by sending electrical impulses along axons, long, hair-like extensions that reach out to neighboring nerve cells. When an electrical signal reaches the end of an axon, the voltage change triggers release of neurotransmitters, the brain's chemical messengers. These neurotransmitter molecules then travel across the space between neurons at a synapse and trigger an electrical signal in the adjacent cellor not.

"Most known synapses act as information filters, and both the probability and the extent of neurotransmitter release as well as the efficacy of the postsynaptic response depend heavily on the recent history of the synapse," says first author Martha W. Bagnall, Ph.D., a former graduate student in du Lac's lab and now a postdoctoral researcher at the University of California, San Diego. "But no matter whether you go jogging or watch TV on your couch, the VOR needs to accurately match sensory input with motor output," she adds.

When Bagnall and her colleagues took a closer look at the first synapse in the VOR circuit, they found that no matter how fast the sensory neuron was firing, the same amount of neurotransmitter was released. And instead of vacillating, the post-synaptic neuron took the information and transmitted it faithfully.


'/>"/>

Contact: Gina Kirchweger
Kirchweger@salk.edu
858-453-410-01340
Salk Institute
Source:Eurekalert

Related biology news :

1. Emotion and scent create lasting memories -- even in a sleeping brain
2. Key to function of dinosaur crests found in brain structure
3. MU brain imaging center provides research for autism, schizophrenia and Parkinsons disease
4. Brain structure provides key to unraveling function of bizarre dinosaur crests
5. Brain-nourishing molecule may predict schizophrenia relapse
6. Brainy genes, not brawn, key to success on mussel beach
7. Risk and reward compete in brain
8. Food for thought -- regulating energy supply to the brain during fasting
9. Millisecond brain signals predict response to fast-acting antidepressant
10. During exercise, the human brain shifts into high gear on alternative energy
11. Penn biophysicists create new model for protein-cholesterol interactions in brain and muscle tissue
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/21/2016)... 2016 Unique technology combines ... superior security   Xura, Inc. ... secure digital communications services, today announced it is working ... enterprise customers, particularly those in the Financial Services Sector, ... authentication within a mobile app, alongside, and in combination ...
(Date:3/14/2016)... Florida , March 14, 2016 ... the growing mobile commerce market, announces the airing of a ... channels starting the week of March 21 st .  The ... CNBC, including its popular Squawk on the Street show. ... focused on the growing mobile commerce market, announces the airing ...
(Date:3/10/2016)... , March 10, 2016   Unisys Corporation (NYSE: ... Border Protection (CBP) is testing its biometric identity solution ... Diego to help identify certain non-U.S. citizens leaving ... The test, designed to help determine the efficiency and accuracy ... in February and will run until May 2016. --> ...
Breaking Biology News(10 mins):
(Date:4/28/2016)... ... April 28, 2016 , ... Next week on May 5 ... first-in-class technologies for tissue stem cell counting and expansion to gene-editing scientists and ... & CRISPR-based Genome Engineering in Burlington, Massachusetts. , The attention of most gene-editing ...
(Date:4/27/2016)... , ... April 27, 2016 , ... The Pittcon Organizing ... 2019. Chuck has been a volunteer member of Committee since 1987. Since then, ... board of directors and treasurer and was chairman for both the program and exposition ...
(Date:4/27/2016)... , ... April 27, 2016 , ... ... Jon Clark has joined the company as an Expert Consultant. Mr. Clark ... industry collaborations and managing the development of small molecule monographs based on analytical ...
(Date:4/27/2016)... , April 27, 2016 MedDay, ... disorders, today announces the appointment of Catherine Moukheibir as Chairman ... MedDay,s previous Chairman, Jean Jacques Garaud , who contributed ... change is effective immediately. Catherine started her career ... and London .  She held ...
Breaking Biology Technology: