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Biology 202
2000 First Web Report
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Katerina Sioutis

The first fact of human brain anatomy is that even at the gross level, brains are different. But how do these differences come about? If I take the simple and extreme view of genetic influence, our DNA and genetic chemicals should clearly spell out in detail all aspects of development. In this paper I want to ignore the genetic aspect of development and review the evidence for the effects of experience on brain development, the adaptability of the brain for alternative pathways to learning and the impact of experience on memory.

From the extensive amount of research material on the web, I can state with confidence that people have a keen appetite for research information about how the brain works and how thought processes develop. It is a difficult task when considering which findings from brain research are relevant to human learning and I was careful to avoid adopting faddish concepts. Among these is the concept that the left and right hemispheres of the brain should be taught separately to maximize the effectiveness of learning. Another fad concept is the notion that the brain grows in hostile “spurts” according to which specific educational objectives should be arranged. Another widely held misconception is that people use 20% of their brains. This belief arose from the early neuroscience finding that much of the cerebral cortex consists of “silent areas” that are activate by sensory or motor activity. However, it is now known that these silent areas mediate higher cognitive functions that are not directly associated to sensory or motor activity (1).

As the sciences of developmental psychology, neuroscience and cognitive psychology have contributed vast number of research studies details about learning and development have converged to form a more complete picture of how intellectual development occurs (1). In this paper I will touch upon 3 points in hope of clarifying and expanding the knowledge of the mechanisms of human learning. I will begin with introducing neurons and how they change during the development of the brain.

A neuron is a cell that receives information from other nerve cells or from the sensory organs and then rejects that information to other nerve cells, while still other neurons project it back to parts of the body that interact with the environment such as muscles. The junctions through which information passes from one neuron to another are called synapses which can be excitatory or inhibitory by nature. The neuron integrates the information it receives from all of its synapses and this determines the output (2).

During the development process, the “wiring diagram” of the brain is created through the formation of synapses. At birth the brain has a relatively small proportion of the trillions of synapses it will eventually have in place. It gains about 2/3’s of it’s adult size after birth. The remaining of the synapses are formed after birth and a portion of this process is guided by experience (1). There are two ways that synaptic connections are added to the brain. The first way is that synapses are overproduced and then selectively lost. This synapse overproduction and loss is a fundamental mechanism that the brain uses to incorporate information from experiences. The nervous system sets up a large number of connections; experience then plays on this network, selecting the appropriate connections and removing the inappropriate ones. What remains is a refined form that constitutes the sensory and often the cognitive bases for the later phases of development (1).

The second method of synapse formation is through the addition of new synapses which operates throughout the entire human life span. This process is sensitive to experience and is actually driven by experience. This role of experience in wiring the brain has been illuminated by research on the visual cortex in both animals and humans. In humans the inputs that enter the brain from the eyes terminate in adjacent regions in the visual cortex. The two inputs converge on the next set of neurons. We are not born with this neural pattern but through the normal processes of seeing the brain sorts things out (1).

Now that I have given you an efficient amount of background on the brain and how it changes I will focus my attention to alternations in the brain that occur during learning. This aspect of changes in the brain interested me most because it is something we all experience and it is something that seems to have made us all different and unique human beings. Overall studies depict an orchestrated pattern of increased capacity in the brain that depends on experience (1). But are the changes in the brain due to actual learning or to variations in aggregate levels of neural activity?

Animals in a complex environment do not only learn from experiences, but they run and exercise which also activates the brain. Therefore the question is - Can activating alone cause the brain to change without a learning experience? A study was done with four groups of rats. One group was taught to traverse an elevated obstacle course and with practice they became very good at it. The next group was put on a treadmill once a day , the third group had free access to an activity and the last group was the control with no given activity. What happened to the volume of blood vessels and the number of synapses per neuron in the rats? Well, the results showed that learning added synapses but exercise did not. Therefore as observed also in humans, synapse formation and blood vessel formation are two important forms of brain adaptation but they are driven by different physiological mechanisms and by different behavioral events (1).

Another aspect of the development of the brain while learning is the time factor. Brain development is often timed to take advantage of particular experiences that help organize the brain. The development of language in humans is a natural process that follows a certain timetable with its own set of limitations (1). As in the development of the visual system briefly described earlier, the human language development for the capacity to perceive phonemes follows a similar pattern. A phoneme is the smallest meaningful unit of speech sound. It enables us to discriminate the “p” sound from the “b” sound by perceiving the time of the onset of the voice relative to the time the lips part. There is a boundary that exists between “b” and “p” that helps us distinguish between the two. Boundaries like these exist between closely related phonemes and these boundaries reflect language experience (1).

The process of synapse elimination occurs relatively slowly in the cerebral cortical regions that are involved in aspects of language and other cognitive functions. Because different brain systems develop in different time frames this suggest that children’s brains might be more ready to learn different things at different times.

There has been detailed knowledge of the brain processes that underlie language emerging in recent years. There appear to be separate brain areas that specialize in tasks such as hearing words, seeing words, speaking words, and generating words.

Language provides an example of how instructional processes may contribute to organizing brain functions. It is an interesting example because language processes are usually more closely related with the left side of the brain. Specific kinds of experiences can contribute to other areas of the brain taking over some of the language functions. For example, deaf people who are learning sign language are learning to communicate using the visual system in place of the auditory system. Each particular sign language has a unique organization which is influenced by the fact that it is interpreted visually. The perception of sign language depends on parallel visual perception of shape, location and movement of hands. Therefore in the nervous system of a hearing person, auditory system pathways appear to be closely connected to the brain regions that process spoken language. In the brains of all deaf people, some cortical areas that normally process auditory information become organized to process visual information (1). In conclusion, specific types of instructions can modify the brain, enabling it to use alternative sensory input to accomplish adaptive functions in this case being communication.

I have come to my final point about the changes that occur in the brain --- memory. Memory should not be considered a single entity nor a phenomena that occurs in a specific area of the brain. There are actually two basic memory processes: declarative memory (for facts and events- involved in hippocampus) and procedural memory (for skills and other cognitive operations -involved in neostriatum). Different features of learning experience contribute to the durability of memory. For example, there is a superiority effect for pictures when comparing people’s memories for words with their memories for pictures. Research has also found that mind is not just passively recording events but rather it is actively working both in storing and recalling information. In a research paper titled “The Serial Reaction Time task: Learning without knowing or knowing without learning?” it was demonstrated that when a series of events are presented in a random sequence, people reorder them into sequences that make sense when they try to recall them. In an act of efficiency the mind creates categories for processing information and this proves memory processes make relational links to other in formations as a feature of learning (3).

Experience alters the brain structures and specific experiences have specific effects on the brain. The nature of “experience” becomes a very interesting question in relation to memory processes. For instance, children were asked if a false event had ever occurred to them and as verified by their parents they correctly answered false to the false statements. However, after repeated discussions around the false events the children began to identify with the occurrences. After 12 week of these discussions he children were able to give fully elaborated accounts of this false events. Repeating words of events that had never occurred actually activates the same brain regions as events or words that were directly experienced (4).

In summary, classes of words, pictures and other such categories of information which involve complex cognitive processing on a repeated basis activate the brain. Activation sets into motion our long-term memory, and our memory processes treat both true and false memory events the same regardless of the validity of what is being remembered (4). The points I have made about memory are important for understanding learning and explains why experiences are remembered. The most important point is that the mind creates and imposes structure on the information available from our experiences. This brings me to the title I chose for my paper - Intelligence=Learning?. Just as there is an ongoing debate about whether the brain is equal to our behavior there is the questions of is our intelligence equal to our learning experiences. How much of our intelligence is genetically given to us and how much is learned? This is a whole different topic but it is interesting to think about.

In conclusion, neuroscience research confirms that experience plays an important role in building the networks of the brain by actually modifying the brain. Neuroscience is beginning to provide some insights into the dynamic organ we call the brain, shaped to a great extent by experience- by what we have done and are doing today. From these findings it is evident that there are qualitative differences among the kinds of learning opportunities in this world. So what is the right way to learn? Am I learning in the most optimum way - how do I know? This idea raises many questions about our education system and the way we were taught to think, conceptualize and basically do everything we have learned to do . . . Sources 1. Mind and Brain 2. Neurons and their Growth Cones 3. The Serial Reaction Time Task: Learning Without Knowing, or Knowing Without Learning? 4. Gazzaniga, Michael S, Mind Matters : How Mind and Brain Interact to Create our Conscious Lives, Houghton Mifflin Company : Boston, 1988.