INTROS Flashcards
Neurotransmitters
A neurotransmitter is a signalling molecule secreted by a neuron to affect another cell across a synapse.
These chemical messengers impact behaviour by managing automatic responses such as breathing and heart rate, but also physiological functions like learning and managing mood.
Neurotransmitters travel across the synapse (which is the space between two neurons) and bind to receptors on the postsynaptic membrane
Some receptors are excitatory, which means that neurotransmitters binding onto them increases the probability of the neuron firing
Some receptors are inhibitory, so when a neurotransmitter binds onto them, the probability of the neuron firing decreases
Receptors on the postsynaptic membrane can be affected by outside chemicals
Chemicals that bind onto receptors & mimic the effects of a neurotransmitter are known as agonists, while antagonists inhibit the action of a neurotransmitter by blocking the receptor site
An important neurotransmitter is acetylcholine, which plays an essential role in learning & memory
To form memories, many parts of the central nervous system cooperate, and the hippocampus plays an important role
The function of the hippocampus is regulated by cholinergic neurons that come from many brain regions - and the main executor of the cholinergic nervous system is acetylcholine
It has long been believed that ACh promotes the conduction of brain nerves and accelerates information transmission; there are studies that support both sides of this argument
In this essay, the effects of ACh on the behaviour of memory & learning will be discussed in relation to psychological research conducted on this issue
Pheromones
Pheromones are chemical messengers which act outside the body to communicate information with other members of the same species
Sometimes referred to as “exogenous hormones”
Primer pheromones - cause slow, long term physiological changes such as hormonal effects
Signalling pheromones - produce a rapid behaviour effect such as mating
Butenandt who first identified the pheromone bombykol in silkworm moths - bombykol is released by the female of the species & aids in attracting mates
Not clear if this same mechanism is true for humans
If pheromonal communication does indeed play a role in human behaviour, it is not clear where such info is processed
In humans, pheromones are thought to be secreted onto our skin through the apocrine glands (sometimes called as human scent glands)
The accessory olfactory bulb (involved in processing such info in the brains of animals) disappears after birth, & the vomeronasal organ is there, but it appears to be disconnected from the central nervous system
However, there is always a possibility that pheromonal info in the human brain is processed elsewhere
Some of these chemicals include MHC & androstadienone, both of which are believed to affect mating behaviour in humans
THESIS: pheromones & mating behaviour
Neuroplasticity
Neuroplasticity involves changes in the brain’s physiology which may occur over time in response to specific environmental stimuli
May influence human behaviour by restoring old, lost connections & functions that have not been used in some time, enhancing memory & overall cognitive skills
Can occur at beginning of life, when immature brain organises itself, after brain injury to compensate for lost functions or maximise remaining functions, and throughout adulthood, whenever something new is learnt or memorised
Environmental inputs result in the elimination of unused synapses & the creation of new communication paths within the brain known as neural networks
This restructuring can involve both the creation & breaking down of connections
Neuroplasticity occurs on many levels, from the level of a single neuron (synaptic plasticity) to the level of large, interconnected neural networks (cortical remapping)
Synaptic plasticity depends on the activity of the neuron (nerve cell) - if two neurons are repeatedly activated together it is likely that a connection b/w them will form
Similarly, lack of activation leads to neural pruning - this can help to increase the effectiveness & functionality of the more commonly used neural circuits
While neuroplasticity can be observed in response to brain injury, it is also a brain mechanism that underlies such common processes as learning
Hormones
Hormones are chemicals that coordinate different functions in the body by carrying messages through the blood to organs, skin, muscles and other tissues.
A key biological factor in understanding behaviour is the endocrine system which is made up of glands
Glands fall into two categories: endocrine and exocrine.
Exocrine glands secrete digestive enzymes, saliva, and sweat, while endocrine glands are located throughout the body & regulate & release hormones into the bloodstream
Although hormones do not directly influence human behaviour, they can change the probability that a certain behaviour will occur in response to a particular environmental stimulus
Have a variety of functions, from affecting growth & reproduction to regulating mood & stress levels
Unlike neurotransmitters, hormones take longer to produce changes in behaviour, but their effects are longer lasting than action potentials
They can only produce reactions in specific target cells after binding, either by increasing or decreasing their functions
One example of an endocrine hormone is oxytocin which plays a number of different roles in the human body, from maternal behaviours & pair-bonding to altruism & trust
Oxytocin is produced in the hypothalamus and is secreted into the bloodstream by the posterior pituitary gland.
THESIS: oxytocin & social interactions
Genetic Similarities
Genes are segments of DNA inherited by the offspring from the parent
Phenotype = characteristics that manifest on the outside in terms of appearance or behaviour
Genotype = a code for phenotype
Genetic heritability is a measure of how well differences in people’s genes account for differences in their traits or phenotypes
One method used to study and quantify genetic heritability is that of genetic similarity.
The idea behind this method is that individuals who are more strongly related (and thus share a larger portion of their genotype) should demonstrate more similar behaviour or traits, provided that this behaviour is inherited
These methods allow us to determine the relative contribution of genetic inheritance to a certain behaviour, but they do not allow us to pinpoint a specific gene / genes responsible for the behaviour
As genes cannot ethically be manipulated in humans to see the effect on behaviour, family-based studies are an ideal way to assess how genes influence behaviour.
The nature/nurture debate in psychology in its traditional form asks whether behaviour is primarily influenced by genetic inheritance or environmental factors
HOWEVER, an implicit assumption in this debate is that the two factors are independent of one another, which is not completely accurate.
The modern version of this debate recognises the following points
Behaviour can be determined by BOTH factors, & the relative contributions of the 2 factors on observed behaviour can be quantified
Genetic inheritance + environment can influence each other (e.g. niche-picking & epigenetics)
For these reasons, it is now believed that a dynamic interaction exists between genetic inheritance & env., with the 2 factors influencing each other.
