Psychology AOS1

The CNS (Central Nervous System) is made up of the brain and spinal cord

• The CNS integrates and coordinates all incoming sensory information and initiates outgoing messages 

• Commands can be conscious or unconscious 

The PNS (Peripheral Nervous System) is made up of all the nerves outside the CNS

• The PNS carries messages between the CNS and muscles, organs and glands throughout the body 

• There are two subdivisions of the PNS (somatic and autonomic nervous system) 

The somatic nervous system carries sensory (or afferent) information to the CNS. This involves motor (efferent) neurons in the somatic nervous system that are responsible for voluntary movements.

The autonomic nervous system controls the body's internal environment in an self-regulating manner.

The sympathetic nervous system is dominant in response to perceived threats and stressful psychological or physiological stimuli. (examples include: dilated pupils, increased heart rate and breathing) 

The parasympathetic nervous system  has two main functions

1. Maintaining a balanced internal state otherwise known as homeostasis

2. Counterbalancing the energising function of the sympathetic nervous system by lowering arousal and restoring the body to a calm state after a threat has passed

Conscious and unconscious responses 

Conscious responses: response that requires energy, usually involves input from the CNS and can involve decision making or choice

• For example: putting on a jumper when you feel cold, scratching an itch, throwing a ball 

Unconscious responses is any response to nervous system that does not require awareness

• For example: blinking, sneezing or coughing 

Spinal reflexes is an involuntary and unconscious response to a stimuli involving the spinal cord and occurs without input from the brain 

• Spinal reflexes such as withdrawing your hand from a hot subject 

Introduction to neurons and neurotransmitters 

Neurons  are the basic building blocks of the nervous system, used to communicate information around the body. The three different types are:

• Sensory (afferent neurons): which transmit information from the body to the brain 

• Motor (efferent) neurons: which transmit information from brain to body 

• Interneurons: which communicate between sensory and motor neurons 

NOTE: an easy way to remember: 

• S - sensory 

• A - afferent 

• M - motor

• E - efferent 
  

Neurons communicate via a process called neurotransmission which uses electrochemical energy 

• A neural impulse (electrical energy) runs from the dendrite down the axon to the axon terminals 

• The terminal buttons (synapse knobs) then release a chemical substance (chemical energy) 

• The chemical substance, known as a neurotransmitter, crosses the synapse 

• The neurotransmitter is then picked by the receiving neuron via dendrites

A neuron has a resting potential when not activated 

An electrical impulse known as an action potential (or neural impulse) is initiated by the soma and travels along the axon towards the axon terminals 

Neurotransmissions

Neurotransmitters are specialised chemical messengers. They transmit information from one neuron to the next 

• They are transported in the axon

• Released at the synapses
  

• There is a tiny space between neurons, called a synapse where neurotransmitters are released by the terminal buttons, before moving onto the next neuron, via dendrites.

Neurotransmitters are contained in small sacs called synaptic vesicles within the terminal button of the neuron's axon terminal. When a presynaptic neuron fires, the synaptic vesicles move towards the presynaptic membrane and open to release the neurotransmitter into the synaptic gap. 

Excitatory and inhibitory are categories of neurotransmitters according to the effect it has on the postsynaptic neuron. 

• Excitatory neurotransmitters increase the likelihood that the postsynaptic neuron will fire. The main excitatory neurotransmitter in the neuron system is glutamate 

Glutamate plays an important role in learning and the formation of memories in the brain. 

• Inhibitory neurotransmitters decrease the likelihood that the postsynaptic neuron will fire and action potential. The main inhibitory neurotransmitter in the nervous system is gamma-aminobutyric acid (GABA) 

For example, without sufficient levels of the inhibitory neurotransmitter GABA, the activation may get out of control because the effects of glutamate take over, leading to mental disorders such as anxiety. 

Neuromodulators 

Neuromodulators are a subclass of neurotransmitters, they are chemical modules just like neurotransmitters. They can also alter the overall effectiveness of neural transmission in entire regions of the brain. They do this by increasing or decreasing the responsiveness of neurons. 

How does it differ from neurotransmission?

Neuromodulation does not result in excitation or inhibitions of a specific neuron. 

• For example: they can modular the efficiency of synaptic transfer, and strengthen neural pathways involved in learning and memory by activating neurons and triggering long lasting changes to synaptic activity 

Cellular changes that can occur:

• Increase in dendritic receptors in the posy-synaptic neuron (improving post-synaptic stimulation) and increased production of neurotransmitters in the presynaptic neuron. 

Dopamine as a modulator: Dopamine is a multifunctional neurotransmitter with both excitatory and inhibitory effects that is involved in many CNS functions. 

Example: pleasure, attention, mood, cognition and movement

Serotonin as a modulator: It only has inhibitory effects and can help counterbalance excessive excitatory effects of other neurotransmitters, as GABA does with glutamate. 

• Mood stabilizers

• Reduced levels of serotonin is linked with OCD

Example: emotional processing, sleep onset, appetite and pain perception

Synaptic Plasticity 

Synaptic plasticity results in a strengthening or weakening of connections based on activity levels

• Given that glutamate is an excitatory neurotransmitter, it stimulates in a pathway and promotes neural connectivity in general, making our memory stronger. 

There are two important processes involved in neural plasticity:

Long-term potentiation (LTP) and Long-term depression (LTD) 

Long term potentiation 

• Relatively permanent strengthening of synaptic connections resulting from repeated activation of a neural pathway 

Long term depression

• Opposite of LTP, involves relatively permanent weakening of synaptic connections

• Repeatedly lower levels of activity in a neural pathway 

As you modify your technique, both LTD and LTP will be at play, enabling your brain to change and create a more efficient neural pathway. 

The sculpting of LTD and LTP work together to make the process of learning more efficient 

This happens through:

• Sprouting

• Rerouting 

• Pruning 

Sprouting: creation of new extensions on a neuron to allow it to make new connections with other neurons. This occurs through the growth of nerve endings (sprouts) on axon or dendrites by enabling new links including rerouting of existing connections. 

Rerouting: occurs when new connections are made between neurons to create alternate neural pathways 

Pruning: elimination of weak, ineffective or unused synapses (and therefore connections to other neurons) 

Internal and External Stressors 

Any event that causes stress is referred to as a stressor.

The biological response includes various symptoms, such as increase in heart rate and muscle tension. Psychologically includes fear, anxiety or excitement and anticipation.

Internal and External stressors: 

Internal: both the physical pain from an injury and the high expectations you have of yourself are internal. Pain that results from an injury is a biological internal stressor because it is caused by physiological damage to cells in the body, activating pain receptors.

• Biological internal stressor: having an illness, disease or condition that causes unpleasant physical symptoms.

• Psychological internal stressors: results from a person's mental processes - their thoughts, mindset and feelings such as fear. 

External: sources of stress that originate outside of an individual. They include environmental events and social cultural stressors:

• Loud noises and extreme temperatures

• Life events

• Loss of a significant relationship

• Environmental catastrophes

How does the nervous system enable psychological functioning? 

Stress: A psychological and physiological experience that occurs when an individual encounters something of significance that demands their attention and/or efforts to cope.

Stressor: any stimulus (internal or external) that produces stress. 

Types of stress: 

Acute: stress that lasts for a relatively short time

• Negative effects: elevated blood pressure, reduced motivation to persist with a task

• Benefits: release of adrenaline which can motivate us and enhance problem solving ability and physical performance

Chronic: stress that continues for a prolonged period of time

• Ongoing demands, pressures, worries

• When it is over an extended period of time it can be harmful to our health and wellbeing

• Stress can be cumulative - stressors add up 

Distress: a form of stress characterised by a negative psychological state

• Often occurs when stressor presents an undesirable consequence or challenge that is too demanding

Eustress: a form of stress characterised by a positive psychological state

• Occurs when the stressor provides a positive opportunity or circumstance for the individual

ACUTE - RESPONSE: : 

Flight-or-fight or freeze is an automatic, biological response to a perceived stressor that increases our chances of survival in our environment. 

• Acute stress response and is also considered adaptive as it minimises possible harm. 

• When faced with a stressor the most effective and instinctive response is to adopt one option: Flight, Fight or Freeze. 

Flight: which involved avoiding or escaping the stressor (for example: quickly running out of your home to escape an intruder) 

Fight: which involves dealing with the stressor directly (for example: picking up a cricket bat to potentially hit an intruder in your home) 

Freeze: involves the immobilisation of the body such as minimising movement or vocal sounds to avoid detection (for example: hiding quietly in a cupboard when an intruder is in your home)

The Freeze response: Has adaptive value. When attacked by a predator, some animals freeze or play dead.

• Way for the nervous system to prepare to immediately shift into fight or flight action. Therefore it's not considered to be passive but rather a parasympathetic break on certain body systems. 

Chronic stress - cortisol:

If an event is stressful, the adrenal glands are activated as a part of the flight or fight or freeze response.

• Primary stress hormone

• Involved in acute and chronic stress

• Acts more slower with lasting effects 

• Turns off all body systems not required to deal with the stressor

• A surge of stress hormones, including adrenaline and biological responses like increased heart rate and respiratory rate. 

• Has an anti-inflammatory effect - blocks activity of white blood cells as they contribute to inflammation

• Suppress immune system activity to focus energy of fight, flight, freeze 

• Contribute to build up of fat tissue and adds to weight gain

• Colds, flue hypertension, digestive problems, obesity 

• Impaired cognitive performance, learning problems, impaired memory

Gut-Brain Axis 

Gastrointestinal tract = digestive tract = gut

A bidirectional (two way) multifaceted communication link between the central and enteric nervous systems 

Enteric nervous system 

• Subdivision of the autonomic nervous system

• Directly connected to the CNS 

• Comprises 200-600 million neurons 

• The two way communication that occurs between the enteric nervous system and the CNS happens via the vagus nerve and gut microbiota 

Vagus nerve: 

• One of the body's biggest nerve 

• Connects brain to organs in the autonomic nervous system

• Runs from brain to colon

• Sends messages from the gut to the brain including pain and discomfort 

• Sends messages from brain to gut like salivation, secretion of gastric acid we smell or anticipate food. 

Gut microbiota: 

• System of microorganisms 

• Includes bacteria, fungi and viruses

• They can communicate with each other, therefore microbiota can also affect mental processes and behaviour

• Its role is to digest food 

• Can influence the production of serotonin and other neurotransmitters within the gut 

Gut microbiota produce neurotransmitters that the brain uses to regulate psychological processes

Gut Microbiota 

• Enterotype: unique combination of gut microbiota we each possess

• Microbiome: collective term for a population of microbiota in a defined environment - affected by both internal and external factors like diet, infection, disease and lifestyle choices.

• Healthy gut: high levels of microbiota richness (i.e. the number of different species), diversity (i.e. how different they are), and stability, resilience and resistance to significant change over time (e.g. the ability to resist disturbance by an antibiotic medication or poor diet) and to recover a stable state.

Gut dysbiosis: an unbalanced gut microbiome, either in number or type of microbiota

GAS Model - Selye's General Adaptation Syndrome

• Biological model of stress

Hans Selye who made the GAS model

• Shows the immediate and long term effects of stress

• Most researched with rats

• Observed pattern of change

The GAS model is a three-stage physiological response to stress that occurs regardless of the stressor that is encountered. 

Stage 1: Alarm reaction: 

• When the person first becomes aware of the stressor 

• Two substages: shock and countershock 

• Shock: temporary state, ability to deal with stressor falls below normal levels, body reacts as if injured

• Countershock: body rebounds, sympathetic nervous system is activated, resistance to stressor is increased, goes into fff, adrenaline and cortisol are released.

Stage 2: Resistance

• If stress isn’t dealt with immediately, energy is still required, the body continues to respond to cope with the stressor

• Body’s resistance rises above normal level

• Intense arousal of the alarm stage diminishes due to activity of the parasympathetic NS.

• Physiological arousal remains above normal

• Unnecessary physiological processes shut down (e.g. sex drive, digestion, menstruation etc.) so energy can be used on dealing with the stressor

Stage 3: Exhaustion

• If stress is not dealt with in the resistance stage the body can reach exhaustion

• Some alarm reaction changes may reappear but the body can’t sustain resistance and the stressor can’t be dealt with

• Stress hormones are depleted

• Resistance to disease is weak - vulnerable to physical and mental disorders

• Exhaustion symptoms: fatigue, sleep disturbances, severe loss of concentration, vulnerability to anxiety attacks, irritability, depressed mood, jumpiness and crying spells.

• Exhaustion symptoms over a long period: High blood pressure/hypertension, heart disease, gastrointestinal problems. 

• Can be permanent or death can occur

Strengths and limitations of GAS Model:

Strengths:

• identifies biological processes associated with the body’s stress response

• Highlights predictable patterns that can be measured in individuals

• Evidence of relationship between stress and illness

Limitations:

• Research was not conducted on humans

• Doesn’t account for individual differences and psychological factors

Lazarus and Folkman's Transactional Model of Stress and Coping

Talks about encounter (‘transaction’) between an individual and their external environment, and that a stress response depends upon the individual’s evaluation (‘appraisal’) of the relevance of the stressor to his or her wellbeing and their ability to cope with it.

Focus on 2 key factors:

• the meaning of the event to the individual

• the individual’s judgment of their ability to cope with it.

Appraisals: 

Primary appraisal:

• evaluate, or ‘judge’, the significance of the event and whether anything is at stake in this encounter

• outcome of a primary appraisal is a decision about whether the event is irrelevant, benign–positive or stressful - if stressful 

additional appraisals follow

• harm/loss — an assessment of how much damage has already occurred (e.g. ‘I have lost my job’)

• threat — an assessment of harm/loss that may not have yet occurred but could occur in the future (e.g. ‘I mightn’t be able to afford the rent’), 

• challenge — an assessment of the potential for personal gain or growth from the situation (e.g. ‘I’ll get any other job I can and will learn to budget and save money’).

Secondary Appraisal

• evaluate our ability to control or overcome the situation 

• includes an evaluation of our coping options and resources for dealing with the event.

• coping options and resources available may be internal (e.g. strength and determination) or external (e.g. money and support from family or friends).

• If the coping demands of the situation are perceived as being far greater than the resources that are available, then we are likely to experience a stress response.

Reappraisal is an important step in this model, as the consideration of one’s resources can change their perception of a situation.

Strengths and limitations of Lazarus and Folkman's model:

Strengths:

• Responds to changes in individuals response through reappraisal

• Focus on psychological

• Developed model through observation of people (not animals like GAS)

• views stress as an interaction with the environment in which the individual has an active role

Weaknesses:

• Lack of evidence (subjective)

• Overlap between primary and secondary appraisal stages, less discrete and occur more simultaneously

• Some psychologists also doubt that we actually need to appraise something as causing stress in order to have a stress response.

• overlooks physiological responses to stressors.

Coping of stress - use of strategies 

• Coping: a process involving ‘cognitive and behavioural efforts to manage specific internal and/or external stressors that are appraised as taxing or exceeding the resources of the person’ in a stressful situation 

Two types of strategies coping with stress:

• Approach: attempt to deal directly with a stressor (healthy approach)

• Stress because of upcoming exams leads to approach of wanting  to study 

• Avoidance: deal with stressors indirectly (maladaptive and unhealthy) 

• Stress due to pain - leads to trying to ignore the pain 

Comparing effectiveness:

Approach is usually generally considered more adaptive than avoidance strategies. Excessive reliance on avoidance strategies tends to be associated with a number of negative consequences.

Context-specific effectiveness refers to when the coping strategy or mechanism used is appropriate for the unique demands of the stressor.