Quick thinking? It's all down to timing

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Remember hearing people being called slow learners by teachers and parents? That oft-used description of someone who takes a wee bit longer to process information, now has a scientific basis for its existence. Scientists from the NUS Yong Loo Lin School of Medicine have found that the rapidity with which a person is able to grasp, process, understand, store and use information comes down to the speed and timing with which the neurons in the brain fire. The closer the gap between the firing of one neuron and the next, the greater the speed with which the information is received, stored and acted upon.

In other words, when it comes to quick thinking, timing makes all the difference. In making this discovery, Dr. Sajikumar Sreedharan and collaborators have provided fundamental information about the that can critically affect the formation of memory processes. The study was published in Proceedings of the National Academy of Sciences on 01 March 2019.

The capacity to adapt and learn with experience is one of the most intriguing features of the human . The brain is composed of billions of , all connected to many others. The physical connections between neurons, called synapses, are where neurons communicate with each other. Synapses are remarkably plastic—these connections can strengthen or weaken dynamically in response to incoming information. Such changes in the efficacy of the synapses underlie learning and the formation of memory in the brain.

The NUS team found that neurons in the , a brain region critical for the formation of memory, use a surprisingly wide variety of learning mechanisms. One such form of learning, spike-timing-dependent plasticity (STDP), depends on the timing of each pair of electrical spikes ( used to transmit information within neurons) in the pre-synaptic neuron and the post-synaptic neuron (Figure 1). An electrical spike in the presynaptic neuron stimulates the neuron to release neurotransmitters, which travel across the synapse to activate the postsynaptic neuron, where the information is converted back into an electrical spike. When the pre- and postsynaptic neurons are active at the same time (less than 30 milliseconds apart), the connections between them are strengthened. However, when the neuron fires earlier by 30 milliseconds or more, or when the postsynaptic neuron fires earlier by more than 10 milliseconds, the connections are strengthened to a lesser degree.

In addition, the researchers demonstrated that when the pre- and postsynaptic spikes occur at the same time, the increase in synaptic strength persists for several hours, and the synapse can even strengthen weak information so that it gets stored. The effect was specific, working only to strengthen this synapse, not to enhance changes in other synapses. This study reveals how important the split-second timing in neuronal activity is in shaping information processing in the brain.

The researchers could detect the longer-term effects of the inter-spike timing because they studied the synaptic changes for a longer duration (4 hours) than the durations employed in previous studies, which were typically less than 1.5 hours.

The STDP model has been proposed to explain spatial and temporal sequence learning. Moreover, the STDP model comes in handy in various situations where object identification and decision-making have to be done quickly, e.g. projectile avoidance or friend-foe identification. For instance, when a ball is flying toward us, we have to identify the object and its trajectory of travel within a very small window of time, in order to take action swiftly to avoid being hit. Similarly, when we come across another person, we have to decide quickly whether they are a friend or a foe. And this recognition requires the coordinated action of various areas of the brain within an activity timing window explained by STDP.

"Unfortunately, the ability for the brain to change in response to such precise timing of information flow may be lacking in brains affected by Alzheimer's disease, as the hippocampus is particularly damaged in this common cause of dementia. This study may provide the foundation for understanding how such differences alter brain function and also how these changes could be reversed or mitigated. This might enable clinicians to help patients who suffer from memory loss," said Dr. Christopher Chen, Senior Consultant Neurologist, National University Hospital and Director of the Memory Aging and Cognition Centre, National University Health System.

A comprehensive understanding of the factors that shape is critical for our understanding of information processing in the brain. It also helps us to understand how memories are formed. Furthermore, a firm grasp of these neural computational rules can help guide the building of artificial intelligence technology, e.g. , which are inspired by the brain's learning mechanisms.

"In the case of autism spectrum disorder, some of the neural systems are more active than the others. This could be the reason why some autistic people are good at certain tasks like arts or mathematics, but have difficulty socialising. Using artificial intelligence, it might be possible to identify the neural networks that are more or less active and it might be possible to normalise their functioning using STDP rules," said Dr. Sajikumar.

Based on this improved understanding of how normal brains compute information and learn, researchers can identify mechanisms for further study that may be involved in conditions like schizophrenia, depression, sleep loss, stroke, chronic pain, learning disability and Alzheimer's disease.

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More information: Karen Ka Lam Pang et al, Long-term population spike-timing-dependent plasticity promotes synaptic tagging but not cross-tagging in rat hippocampal area CA1, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1817643116
Citation: Quick thinking? It's all down to timing (2019, March 27) retrieved 23 October 2019 from https://medicalxpress.com/news/2019-03-quick.html
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Mar 27, 2019
With greater wisdom people answer questions much slower because they consider more variations, more confounding conditions, more variables and so on. The lower a person's wisdom the quicker they are to answer a question, especially questions like "What is consciousness?" or "What is Life?" and they will be confused, astounded and/or frustrated when it is suggested to them the question is deeper and requires further thought. Speed of response does not correlate to intelligence and has no relation to wisdom unless the question asked has only one answer eg "what is 3+2?". Computers are even faster at answering such questions making this skill increasingly irrelevant to non-computer intelligences.

Mar 27, 2019
@RobertKarlStonjek Totally irrelevant to the subject of this study. Reaction speed between neurons correlates with the speed of information processing. If by wisdom you mean the accumulation of experiences, then the increase of information processing speed will result in faster analysis of these experiences and faster arrival to the proper conclusion.

Mar 27, 2019
I'm gonna have to think about this one..

Mar 31, 2019
Pratyeka, there is a difference between the response to a question and the processing speed of neurons. In a healthy brain the neurons will be processing information faster. But that does not necessarily mean that a response will also be faster when asked a question.

A wiser individual is able to consider a problem from multiple perspectives, but this takes time. A less wise but very intelligent person will have only one or two perspectives to consider and so will be able to answer quicker.

That is why the questions asked in such tests must be absolutely unambiguous and have only one possible answer and for the participants to be informed of this.

Entertaining IQ test questions meant to fool the unwise, for instance, elicit a quick but response from some, but others will contemplate the question and discover the hidden deeper answer.

Conversely, if one *suspects* a trick question then even obvious questions will be answered slowly while alternatives are contemplated.

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