Hebbian Learning, Neural Basis of Learning

psychpost | 5/27/2012 11:01:00 AM | 5 Comments


While studying Psychology, students will encounter many different explanations and theories answering the question: "What is learning?" Hebbian Learning is a Biological Neuroscience explanation of what learning is and what occurs during learning.

"Cells (neurons) that fire together, wire together." (Carla Shatz, Stanford University)
 
The basic idea of Hebbian Learning is that there is an increase in connectivity between neurons when one of them repeatedly stimulates another. This increase in synaptic strength allows the two neurons to communicate more efficiently.

Nature and Nurture

psychpost | 5/14/2012 12:24:00 PM | 5 Comments

Correlation of traits in twins, sibling, and adopted siblings.
In the study of Developmental Psychology the question: "How do Nature and Nurture interact to cause Development?" is asked about every single finding, idea, and concept you can imagine.

For those not familiar with these ideas here are the basics:
-Nature refers to our  biological/genetic inheritance. More specifically if refers to our genes and all the traits and features associated with our genome.
-Nurture refers to the physical and social environment that influence our development.

An error when thinking about nature and nurture is to ask if either nature of nurture is responsible for a certain aspect of development. This is an error because every characteristic that we have is created through an interaction of our genetics and our environment. In the graph above we can see that some traits are highly correlated with genetics (twins). In the same graph we can also see that certain traits hive high correlation even among adoptive siblings who do not share genetics but share a similar environment.

Correlation Does Not Equal Causation

psychpost | 5/06/2012 08:00:00 AM | 1 Comment
Different types of correlation. [image source]
The dependence (or association) between two different variables is known as their correlation. Correlation is a very important tool for finding trends and as a starting point for research. A positive correlation is a relationship in which an increase in one variable accompanies an increase in another. A negative correlation is a relationship in which an increase in one variable is accompanied by a decrease in another (or vice-versa).

A very common mistake when looking at correlational data is that the reader may interpret the results to be causal (X causes Y). Although this conclusion can be very appealing, there are two problems which we encounter.

Problem 1, Direction-of-causation problem: A correlation between two variables does not carry information about which variable causes what effect. When looking at two correlated variables, X and Y, it is possible that X might cause Y or that Y might cause X.

Problem 2, Third-variable problem: The correlation of two variables may actually be the result of a third variable that is not taken into account. A popular example of this third-variable problem has been seen in research about children's IQ scores being positively correlated with mothers breastfeeding them as infants. The problem with this early research is that mothers of higher Socioconomic Status are more likely to breastfeed than women of lower SES. This third variable, Socioeconomic Status, is known to have positive effects on many variables including IQ score (for high SES) and also negative effects (for low SES).

Synaptic Pruning, Neural Darwinism

psychpost | 5/03/2012 10:32:00 AM | 1 Comment

Visual representation of the pruning. [source]
Very early on in human life, around weeks 3 and 4 of prenatal life, Neurogenesis occurs. During this period there is a very high rate of new neurons forming in what is to become the infant's brain. During this rapid creation of neurons there is another process at work known as Synaptogenesis.  Connections between neurons that allow them to communicate to one another are known as synapses. In early life there is an excess of these synapses present in the brain.

The fate of these excess neurons and synapses will be determined by Synaptic Pruning. The goal of this pruning is to eliminate connections which are unnecessary, not used often, or are not useful. One way of looking at this process is to think of the quote "Use it or lose it". This process is also known as Neural Darwinism because like evolution, only the 'strong' neurons and synapses survive into adulthood.  This process begins before a baby is born and continues up until early adulthood. This pruning represents brain maturation and is also believed to represent learning. In total, around 50% of neurons and synapses are eliminated via this process.

Synesthesia

psychpost | 5/01/2012 08:06:00 AM | 3 Comments
Synesthesia Art. Source
Recently during my previous quarter at the university I had the opportunity to see guest lecturer, Romke Rouw from the University at Amsterdam, give a short lecture on Synesthesia. It was a very interesting and fun topic and I will be giving a short overview in this post.

Synesthesia: A perceptual experience in which a stimuli evokes another experience. In Synesthesia these experiences are not related to neurological, psychological, or psychiatric disease. An example of Synesthesia : hearing a particular instrument causes seeing a color.