psychology exam revision

what are nerves

• Nerves are tightly bound bundles of neurons.

what is a neuron

A neuron is an individual nerve cell that is specialised to receive, process and/or transmit information.

types of neurons

• sensory

• motor

• interneurons

sensory neurons

• (afferent) – transmit information from receptors in the body to the Brain (CNS).

motor neurons

• (efferent) – transmit information regarding movement from the brain (CNS) to the muscles in the body.

interneurons

enable sensory and motor neurons to communicate and are located within the brain and spinal cord (CNS) only.

structure of a neuron (image)

what does dendrite do

• Receives messages from the pre-synaptic neuron. 

• They have receptor sites which receive specific neurotransmitters 

what does cell body do (soma)

• Combines the neural information from dendrites  and sends it to axon 

• Contains Nucleus which has biochemical info to keep neuron functioning

what does axon do

• Carries the neural impulse towards the axon terminals.

what does myelin sheath do

• Layer of fatty tissue around the axon.

•  Insulates/speeds up neural transmission and protects the axon from interference. 

what do axon terminals do

• Branches at the end of the axon.

• Contain vesicles that store neurotransmitters at the tip of the axon terminal and release them into the synapse. 

what is pre-synaptic neuron

• The neuron that is located before the synapse.

what is post-synaptic neuron

• The neuron that is located after the synapse.

what is synapse

• This location is where communication between neurons occurs.

• It includes the pre-synaptic axon terminal, the synaptic gap and the post-synaptic dendrite.

what is synaptic gap

• The space between the pre and post-synaptic neurons.

what are neurotransmitters

• Neurotransmitters are chemicals that carry neural messages across the nervous system.

• spread out or “diffuse” across the synaptic gap/cleft

• will only bind or fit into specific postsynaptic receptor sites that match chemically. 

what happens when neurotransmitters fit/do not fit

• If they fit, and enough of them bind to their specific receptors, then an action potential/nerve impulse is triggered in the postsynaptic neuron.

• If a neurotransmitter does not fit/or are released from a receptor it will remain in the cleft for a short time before being recycled (this is called “reuptake”) 

neurotransmitter effects

• Excite the postsynaptic neuron

  • An action potential will more likely occur in the postsynaptic neuron

• Inhibit the postsynaptic neuron

  • An action potential is less likely to occur in the postsynaptic neuron

glutamate

• A major excitatory neurotransmitter.

  •  increases the likelihood of an action potential being fired.

• Enhances learning and memory.

• Helps form and strengthen synaptic connections

GABA

• A major inhibitory neurotransmitter.

  •  Decreases the likelihood of an action potential being fired

• Prevents uncontrolled activation of neurons in the brain.

• Helps control anxiety, stress and the sleep–wake cycle and plays an important role in maintaining the overall balance and stability of neural circuits.

• Plays a role in reducing anxiety and promoting relaxation

what are neuromodulators

• Neuromodulators adjust or regulate neurotransmission

• subclass of neurotransmitters

  • Not all neurotransmitters we study are neuromodulators 

what do neuromodulators do

• alter the overall effectiveness of neurotransmission

•  influence neurotransmission effectiveness. 

• Neuromodulators are very slow to perform their task compared to neurotransmitters

neurotransmitter site of release and target

• site of release: into the synapse

• target: a single post-synaptic neuron

neuromodulator site of release and target

• site of release: outside the synapse into the neural tissue in the brain regions

• target: groups of neurons

what is dopamine

• Dopamine is a multifunctional neurotransmitter with both excitatory and inhibitory effects

• Dopamine is involved in many CNS functions in addition to pleasure, such as movement, attention, mood, cognition and motivation.

dopamine as a neuromodulator

• As a neuromodulator, dopamine fine-tunes the effectiveness of signal transmission at the synapses, affecting the activity of a network of neurons.

reward pathway

• refers to a group of structures in the brain that are activated by rewarding or reinforcing stimuli

• It also triggers memory regions of the brain to pay attention to all the features of that rewarding experience, so it can be repeated in the future

dopamine in addiction

• act as a motivating agent

• associated with unhealthy and addictive behaviours.

dopamine theory of addiction

• suggests that most addictions are caused by the brain’s inability to produce dopamine naturally without the behaviour or the substance that someone is addicted to.

• e.g gambling, gaming

what is serotonin

• Serotonin is mostly an inhibitory neurotransmitter. 

• involved in modulating mood, perception, anger, reward, aggression appetite, memory, sexuality, and attention. 

serotonin as a neuromodulator

• As a neuromodulator, serotonin modulates the activity and function of neural circuits rather than directly transmitting signals between individual neurons. 

serotonin in mood

• Balanced levels of serotonin generally correlate with calm, focussed, happy, & stable moods. 

• Low levels of serotonin correlate with an impaired ability to regulate mood. 

serontonin and the gut-brain axis

• 90% of the serotonin in the human body is found in the gastrointestinal tract.

synaptic plasticity

• The ability of synaptic connections to change over time in response to activity or experience

sprouting

• Sprouting is the process by which a neuron’s axon or dendrites grow to form new connections with other neurons.

• typically occurs in response to damage,

• neighbouring neurons may extend their axons or dendrites to establish connections with an affected area. 

rerouting

• create an alternative neural pathway. 

• s allows neural signals to be redirected and new neural pathways to be formed.

• original connections are disrupted or lost. The healthy neuron adapts and establishes alternative connections to maintain functional neural communication.

pruning

• selectively eliminating or reducing specific neural connections and synapses to refine and optimise the wiring of the brain. 

•  begins in childhood and continues into adulthood.

• helps refine sensory pathways

long-term potentiation

• Repeated coactivation of the presynaptic neuron and postsynaptic neuron strengthens the synaptic connection between these neurons.

long-term depression

• The weakening of a neural synapse involves infrequent release and/or insufficient release of neurotransmitters into the synaptic gap.

functional changes of LTP

• Larger number of neurotransmitters released by the presynaptic neuron

• Sensitivity of neurotransmitter receptors on the postsynaptic neuron may also increase. 

structural changes of LTP

• The axon terminals of the presynaptic neuron may undergo growth, forming more synaptic contacts with the dendrites of the postsynaptic neuron. 

• Number of neurotransmitter receptors on the postsynaptic neuron may increase

functional changes of LTD

• Smaller number of neurotransmitters released by the presynaptic neuron

• Sensitivity of neurotransmitter receptors on the postsynaptic neuron may decrease. 

structural changes of LTD

• The axon terminals of the presynaptic neuron may be pruned, reducing the number of synaptic contacts with the dendrites of the postsynaptic neuron.

• Number of neurotransmitter receptors on the postsynaptic neuron may decrease. 

divisions of the nervous system

• central nervous system

  • brain

  • spinal cord

• peripheral nervous system

  • autonomic

  • somatic

brain in the CNS

• Analyses sensory information and directs future responses

• Responsible for directing both conscious responses (kicking a ball) and some unconscious responses (breathing regulation) 

spinal cord in the CNS

• Receives sensory information from Peripheral Nervous System (PNS), transporting these messages to the brain through interneurons (if required).

• Receives motor decisions from the brain and relays these back to the Peripheral Nervous System (PNS) through interneurons.

somatic in the PNS

• Carries information from sensory organs (eyes, ears, skin etc) through sensory neurons (via afferent pathways) to the CNS

• Carries information from the CNS through motor neurons (via efferent pathways) to skeletal muscles that cause USUALLY voluntary or conscious movement

autonomic in the PNS

• Carries information from sensory and internal (visceral) organs through sensory neurons (via afferent pathways) to the CNS

• Carries information from the CNS through motor neurons (via efferent pathways) to internal (visceral) organs that guide usually involuntary or unconscious regulation of organs

autonomic divisions

• sympathetic

• parasympathetic

• enteric

enteric nervous system

• Regulates actions of the gastrointestinal tract (i.e. digestive system).

• Can work independently of the brain, E.g. regulation of digestive enzymes etc.

• Can also communicate directly with the brain via the vagus cranial nerve
  

Sympathetic Nervous System

• Becomes more dominant in times of vigorous activity, stress, excitement or threat

• Prepares the body for action

• Fight or Flight is activated when under threat

parasympathetic nervous system

• Becomes more dominant when the body is at rest or returning to homeostasis

• Takes longer to return to homeostasis,

• It facilitates bodily functions during rest and inactivity.

• The parasympathetic nervous system becomes dominant during freeze

concious repsonses

• Responses that involve awareness

• Usually voluntary, goal directed and we have some degree of control over it

• Often learnt behaviours

• Brain required to make a conscious choice!

concious repsonse steps

• stimulus interacts with us

• sensory receptors pick up change

• Sensory neurons in the PNS send the message (via afferent pathways) to the spinal cord.

• Interneurons in the spinal cord transfer/relay this information to the brain and then from the brain to motor neurons

•  Motor neurons (via efferent pathway) take the message from the CNS to the PNS area needed (muscle/gland/organ)

• response: Skeletal muscle/ gland/organ reacts

unconcious responses

• Does not involve awareness

• Not learnt - present from birth!

• Is involuntary, unintentional and automatic 

• Spinal cord mostly coordinating!

spinal reflex

• An unconscious, involuntary and automatically occurring reflex, that occurs in response to certain stimuli without any involvement of the brain.

• Follows a “reflex arc”: Automatically reflected back from the spinal cord to the muscle

• Is adaptive: faster reaction time

stress definition

• Stress is a psychobiological process,

• to something that is perceived as challenging or threatening our ability to cope. 

stressor

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

• internal

• external

internal stressor

• Stimulus from within the person’s body

• Can be personal perception of events or biological responses

external stressor

• Stimulus outside a person’s body

• Interaction with the environment

stress responses

Changes in psychological (including appraisal) and/or physical state

coping mechanisms

Actions to try and cope with the stressor and biopsychological states

acute stress

• stress that lasts for a relatively short time

• Body typically bounces back well

Occurs quickly after the perception of a threat: 

• Activation of sympathetic NS

fight

Involves dealing with the stressor directly;

flight

Involves evading or escaping the stressor;

freeze

Involves the immobilisation of the body such as minimising movement or vocal sounds to avoid detection;

chronic stress

• When a stressor is not dealt with, is severe or ongoing,

  • Tends to be worse for your body

when is cortisol released

If a stressor is not adequately addressed relatively immediately then cortisol is released:

what does cortisol do

• boosting our energy levels 

• heightening our alertness

• increasing the body’s ability to repair tissue

• diverting energy from non-essential bodily functions 

• pain-reliever

• Suppresses the immune system

gas model stages

• stage 1: alarm reaction

• stage 2: resistance

• stage 3: exhaustion

stage 1: alarm reaction

• shock

  • first aware of stressor-body goes into temp state of shock 

    Ability to deal with stressor falls below normal

• counter- shock

  • Sympathetic nervous system activatesAdrenaline and cortisol released into blood stream

  • Ability to deal with stressor increases 

stage 2: resistance physiological process

• physiological arousal remains above normal

• Unnecessary processes shut down 

• Cortisol in  blood stream energises

• Ability to deal with the stressor remains above normal

stage 2: resistance signs and symptoms

• Continued release of cortisol→ decreased immune function and decreased ability to cope with new/other stressors:

  • mild physical ailments 

  • Changes in behaviour

• If stressor is successfully dealt with→ body eventually returns to homeostasis

stage 3: exhaustion physiological process

If stress is still not dealt with

• body cannot sustain its resistance

• Resources begin to deplete

stage 3: exhaustion signs and symptoms

• Prolonged release of cortisol and depletion of resources:

• Serious Physical illness

GAS model strengths

• Considers physiological response of stress over time

• Suggests a predictable pattern of responses that can easily be tested in a laboratory with clear evidence.

• Identifies various biological processes that occur as a part of the stress response,

• ink between stress and disease

GAS model limitations

• Does not provide intervention strategies

• Overemphasis on the biological process

• Does not examine individual differences in responses

• Age of model

• Used Rats - generalisability to humans is limited

lazarus folkman model steps

1. interaction or transaction between an individual and their external environment

2. active role in interpreting the stressor

3. Interpret a situation as stressful or not depending on their appraisal

   1. Primary Appraisal: Does it affect me? What is at stake? What could be gained?

   2. Secondary Appraisal: Do I have resources to cope
      

Lazarus and Folkman model

Lazarus folkman model strengths

• Allows for the fact that stressors and the circumstances under which they occur can change over time

• individual has an active role in their own stress response and can therefore learn to respond and manage it.

• Study based on human subjects

• Allows for consideration of cognitive/psychological processes within the stress response

lazarus folkman model limitations

• Individuals may not always be consciously aware

• Difficult to study experimentally and measure, as appraisals are subjective

• Primary and secondary appraisals sometimes occur at the same time, or secondary appraisals occur first. The model does not allow for any variation

• Underestimates role of physiological process in influencing stress response 

• does not account for external, sociocultural factors that may influence stress

what is the gut-brain axis

• A bidirectional (two way) communication link between the central nervous system and enteric nervous system

vagus nerve

• nerve that connects the brain (CNS) to organs within the autonomic nervous system,

• controls many crucial bodily functions, including mood, immune response, digestion and heart rate.

• signals sent ‘up’ and ‘down’ from gut to brain

gut microbiota

• microorganism in stomach

• unique

healthy gut descriptors

• Microbiota diversity and high population

• Resistant to disturbance 

• Able to recover to a stable state

gut dysbiosis descriptors

• changes in production of neurotransmitters

• Digestive disorders, 

• Cognitive functioning, mood disturbance, mental health disorders

Chronic stress, cortisol, and the GBA

• A weakened immune system due to chronic stress can change our gut microbiota and lead to dysbiosis

• Imbalanced microbiomes have been linked to health problems such as allergies, autoimmune diseases, metabolic disorders, and mental illnesses. 

microbiota and GABA

• certain microbiota in the gut are associated with the production of GABA.

• Bacteroides produce GABA in the rat digestive tract

• More GABA-producing bacteria in the gut were found to reduce learned helplessness

how to improve gut health

• using probiotics containing ‘good’ strains of bacteria “ Psychobiotics”

• healthy faecal microbiota transplants

• specific diets

  • beneficial in reducing the physiological stress responses and negative effects of stress,

coping strategy meaning

• A specific method, behavioural or psychological, that people use to manage or reduce the stress produced by a stressor.

approach coping strategies

• Confronts stressor and effects directly

• Activity is focused towards the stressor

• Aims to address the underlying problem

• involve engagement with the stressor

avoidant coping strategies

• Evades a stressor to address effects indirectly

• Activity is focused away from the stressor 

• no attempt to actively confront the stressor

• behavioural or emotional disengagement

approach coping strategies benefits

• Approach strategies are generally considered to be more adaptive and effective

• People who rely more on approach strategies to cope with a stressor tend to experience fewer psychological symptoms

approach coping strategies disadvantage

• Initially or in the short term, approach strategies may increase stress levels

• approach strategy may require a lot of the individual’s energy and focus

avoidance strategies benefits

• ‘switching off’ may be considered an adaptive strategy.

• Disengagement might be appropriate in a situation where nothing can be done.

• allows you to conserve energy

• can be more effective in coping with stress in the short term.

• ‘time out’ from a stressor while minimising potential stress from another source.

avoidance strategies limitations

• Excessive reliance on avoidance strategies tends to be associated with several negative consequences,

• tend to be maladaptive.

• can also contribute to other problems

• strategies tend to only be helpful in the short term

• Delaying actually dealing with a stressor can also have negative consequences

coping flexibility

• ur ability to modify our coping strategies to meet the demands of different stressful situations. 

• relinquish an ineffective coping strategy and to devise and implement an alternative, more effective strategy. 

context-specific effectiveness

strategy can meet the specific demands of the situation and suits the person using it

what is classical conditions

• It involves pairing two stimuli together (one that does not elicit a reflex and one that does), so that an association is formed between the two stimuli.