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The neural basis of learning

Learning is a process by which we integrate new knowledge generated as a result of experiences. The product of such experiences is converted into memories stored in our brain. There is basically no learning without memories.

There are essentially two ways in which learning occurs: one is called classical conditioning and the other instrumental conditioning. Both ways modify brain structure and brain chemistry, but they do so with varying degree of awareness or self-control. Classical conditioning pertains to situations in which we tend to respond automatically, based on the severity or repetition of a stimulus. The amygdala is involved in regulating many of our autonomic, fight or flight type responses. For instrumental conditioning, more brain structures appear to take an active role in encoding and reinforcing a learned behavior. For instance when we learn driving, the repetition or rehearsal of that behavior will involve the perceptual and motor systems as well as the frontal lobes. As the behavior is memorized, it is managed by the basal ganglia. People who have lesions in the basal ganglia have severe deficits in their capacity to learn via instrumental conditioning. The process by which we learn new behaviors is also largely influence by specific neurotransmitters, especially dopamine which is known to reinforce or reward specific behaviors by making us feel good about it.

Memory is typically described as either short or long-term. Short term memory is also called working memory and can last from several minutes to a few hours. The front lobes are known to play a very important role in the short term memorization while the hippocampus is critical in consolidating information into long term storage.

To understand the anatomical changes that are happening in the brain as a result of learning or the creation of memories, we need to go back to the basis of brain functioning: synaptic connections.

The Neurological Basis of Learning and Memory

Though we now recognize that there are different forms of learning such as classical conditioning and instrumental conditioning and several types of memory from short term to long term, all these processes in our brain depend on our ability to detect, decode and respond to a change captured by our perceptual systems. For instance, a visual stimulus triggers a response that results in the formation of thousands of synapses in our brain. Our eyes capture photons that our visual neural pathway converts into electrical signals reaching different receptors in the brain via the optic nerve. The stimulus ultimately generates action potentials among thousands of neurons responsible for processing the signal and triggering a response. The signal is either amplified or minimized based on the intensity of the stimulation –the intensity of the light for instance–, its frequency and the presence or absence of the many molecules involved in exciting or inhibiting the chemical exchange in the synaptic cleft such as hormones, neurotransmitters and neuropeptides.

The process of learning and memorization develops neural efficiency by making new synaptic connections or by reinforcing the strength of existing ones. When neurons fire together, they wire together. Neuroscientists call this phenomenon synaptic plasticity.

Understanding Synaptic Plasticity

A considerable amount of brain research has been produced on learning and memorization over the last decade. We understand that learning is produced when the nature and structure of synaptic connections change, especially when postsynaptic neurons are affected by anatomical and biochemical alterations inflicted on axons. Early studies on learning used electrical stimulation within the hippocampal formation, a brain structure known to play a critical role in memory formation. Those studies revealed that the stimulation produced more long term potentiation (LPT). The discovery of LPT proved what Donald Hebb (1949) suggested over 50 years ago while trying to describe a law that would explain the process by which we remember in our brain. Hebb proposed that “if a synapse repeatedly becomes active at about the same time the postsynaptic neuron fires, changes will take place in the structure or chemistry of the synapse that will strengthen it (Carlson, 2008: p 432). More recent research reveals that the process of LPT is largely governed by chemical reactions between important receptors such as NMDA and AMPA receptors. NMDA receptors can actually block LTP by making it impossible for calcium ions to enter dentritic spines, a chemical process that is necessary to strengthen synapses between neurons while AMPA facilitates the release of glutamate which can amplify a post synaptic potential.

The study of structural changes in the brain as a result of learning and memorization has received a considerable boost since neuroscientists have used imaging technology such as fMRI in the mid 90s. With fMRI, scientist can see the brain at work, specifically they can map which areas of the brain are most active in given circ***tances by tracking blood flood. For instance, research conducted by Bogdan Draganski and his colleagues of the Department of Neurology of the University of Regensbug Germany (Draganski &, 2006) demonstrated that gray matter volume increases as a result of learning. The process by which we generate new neurons is called neurogenesis and is the condition that makes it possible for us to increase our capacity to learn and memorize.

Though it is still very difficult for Neuroscientists to crack the neural code of both learning and memory, we do know that the production of new neurons is primarily possible in the hypothalamus, the brain area mostly responsible for creating and maintaining our long term memories. We also know that we do produce new neurons as a result of learning activities at any age, which is why additional research in this area is so critical to the future of neuroscience.

hormones

Biological basis of behavior explained : what you should know about hormones, peptides and amines

Hormones are chemicals produced by our body to regulate three critical functions: maintain a state of balance (homeostasis), control our reproductive organs and mediate our responses to stress. Hormones are produced by endocrine glands located in various parts of the body, namely the brain, the stomach, the intestines and the kidneys. Hormones affect cell receptors that are either on the surface or inside the nuclei of a cell. They excite or inhibit the activity of cells; therefore they can profoundly modify both our conscious and subconscious behaviors.

Because hormones use the blood circulation system, they are rather slow to act compared to neurotransmitters for instance. However, the reach of hormones is more global. In fact, some hormones reach beyond the body itself like pheromones, which act to influence another person or animal. Pheromones are processed by our olfactory system and are known to strongly influence our sexual behavior.

Homeostatic hormones
Homeostatic hormones have a direct impact on the internal balance of our body. To function properly, we need specific levels of vital components in our bloodstream such as sugars, proteins, salts, carbohydrates and water. Insulin is an example of a homeostatic hormone. The role of insulin is to regulate glucose levels in the blood.

Gondola hormones
Gondola hormones are responsible for giving us our sexual appearance as well as mediating many of our sexual behaviors. Testosterone is known as the male hormone because it is responsible for masculinizing the brain.

Stress Hormones
Stress hormones help us respond to situations that deserve immediate attention such as threats or states of intense arousal. The hormone controlling the fast stress response is norepinephrine which is triggered by a neural signal from the hypothalamus. Norepinephrine activates cells to provide more energy to the entire body. The slow response to stress is mediated by another hormone called cortisol. Slower to produce its effects, cortisol does impact many organs and cellular structures to help the body respond to stress.

How do Peptides, Amine and Steroid Hormones Differ?
Peptides, amine and steroid hormones differ primarily in their cell structures, by the way they are either reused or discarded biologically, and by the nature of the biochemical impact they have on our physiology. Finally, they differ by the speed at which they produce results. We discuss those differences next.
A peptide hormone is made by cellular DNA in the same way a protein is made. It influences cellular activity by binding to receptors on the cell membrane which then generates a second reaction. Once peptides are released, they are destroyed by enzymes and there is no reuptake or recycling. One of the best known families of neuropeptides is endogenous uploads. These peptides have powerful effects on our nervous system by acting on our pleasure and pain sensations. They tend to act rather slowly. Also because they are considered large molecule structures, synthesized peptides are not taken orally.
Amines constitute a group of neurotransmitters that are synthesized in the same way and produced in the reptilian part of our brain: the brain stem. Amines are small molecule structures that play a huge role in our nervous system. Unlike peptides, they act quickly in the synaptic cleft. They also can be replaced or recycled. Amines are made of components we get from our diet so when synthesized as drugs, they can be ingested to reach the brain. Dopamine, noradrenalin, epinephrine and serotonin are four of most critical amines we depend on to regulate attention, learning, mood, aggression, pain, appetite and many more vital aspects of our biological responses to stimuli.

A steroid hormone is a small fat-soluble molecule which directly affects the protein because it pa**** easily through cell membranes to reach the nucleus. It is synthesized from ch***sterol. Indeed, ch***sterol provides substance to many cells in our body. Some of the main steroids produced by our body are estrogen, cortisol, progesterone and testosterone.

Steroid hormones diffuse away from the glands in which they are produced such as the adrenal cortex in the brain, the gonads and the thyroid

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How is Secretion Rate Monitored and Controlled?
The control and release of hormones is organized among the brain, the pituitary and the endocrine glands. Within the brain, it is mainly the hypothalamus that triggers activation of the pituitary gland which then secretes hormones that flood our entire body. Since most neurons have receptors on which hormones can act, the effect of hormones is widespread and profound. Testosterone for instance, can affect a cell at the genetic level because it reaches the nucleus where genes can be turned on and off. Because hormones travel through the circulatory system, they can reach any part of the body. Hormones are somewhat self-regulated because they also provide feedback back to the brain in order to alert our nervous system for the need to increase or reduce their levels.

neurons

From neurons to hormones: understanding the biological triggers of our actions.

The neural communication systems is built on billions of interconnected cells called neurons which communicate by exchanging chemicals, most of which are triggered through electrical stimulation produced by specific stimuli. The endocrine system provides another communication system which is carried by hormones synthesized by glands distributed in different places throughout the human body, one of which is actually in the brain: the pituitary gland. The pituitary gland secretes many hormones, especially some that actually control the production of other hormones. Both systems constitute the major ways by which our body is regulated. Both are interconnected and do interface in complex ways.

Both systems create a sophisticated web of responses that affect our behaviors and the body’s homeostasis. The neural system directly controls the production of many hormones. Likewise, some hormones act as neuromodulators which affect the nature of synaptic connections between neurons. There are, however, important functions that make both communication systems distinct and explain why one system may offer advantages or disadvantages over the other. We will discuss here four factors: structural design, speed, the length of impact and distance of action.

Structural Design
The nervous system is wired whereas the endocrine system is not structurally linked. In other words, neurons are connected through a logical grid; glands are not. This makes the neural network speedy and efficient. However, nerve cells must have a close anatomic connection with each other to communicate. Hormones can travel to any other part of the body. Though they are not as limited in that respect, they must find the right target receptors in order to produce any effect.

Speed
The neural system is considered fast and the hormonal is fairly slow in comparison. Reactions at a neural level happen in milliseconds. By contrast, the way hormones are secreted and travel through the bloodstream make them slow-acting once they bind with the appropriate receptors.

Length of Impact
The impact of a neural connection tends to be short and requires repetition to produce long-lasting effects. On the other hand, hormones can generate responses that affect the body even after the binding to the receptors has ceased. Specifically hormones that affect the production of proteins have longer effect than those that are just activating enzymes.

Distance of action
Though axons can be quite long in order to cover the distance between the brain and some of the most distant points of the spinal cord, the nature of neural transmission is that it is more local than global by design. By using the bloodstream as a channel through which it reaches target sites, hormones have more outreach than neurons in the way they communicate and impact the body.

As different as both systems may be on the issue of structural design, speed, length of impact, and distance of action, both systems support the way our body maintains a state of homeostasis when facing stress, external stimuli, and many other of life’s attempts to disrupt our state of balance.

fastcompany

Fast Company Features Patrick Renvoise

Fastcompany features Patrick Renvoise in seminal article discussing the use of neuromarketing by major political candidates. For more, click here.

There are a multitude of reasons the Republicans regained control of Congress in Tuesday’s elections–unemployment, voter discontent, tea party-ism. But the one influential factor you aren’t likely to hear about is the use of political neuromarketing during the campaign…. read more.