Psychobiology Flashcards
1
Q
Central Nervous System
A
Includes the brain and spinal cord.
The brain coodinates sensation, perception, thinking, awareness. It is 2% of our whole weight. It takes 20% of our oxygen and calories.
The spinal cord acts as a pathway for neural impulses.
They take in and send out information to entire body.
2
Q
Peripheral Nervous System
A
Includes the somatic nervous system- plays a role in voluntary movements and sensory processing. Carries motor and sensor neurons to and from the CNS. Motor neurons (efferent neurons) carry info from the brain and spinal cord to muscle fibres. Sensory neurons (afferent neurons) carry information from the body to the CNS. This system is able to control our physical movements and process 4/5 of our senses. Somatic nerves include both cranial spinal nerves. There are 12 pairs of cranial nerves and 31 pairs of spinal nerves.
Also includes the Autonomic Nervous system (involuntary behaviours) which consists of the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic NS controls our fight or flight responses and kicks in when we are confronted with something stressful. Regulates things like: heart rate, stress, digestion, dilating pupils, encouraging glucose. It does these things to help us manage the stress. It communicates through neurotransmitters such as adrenaline and noradrenaline.
The parasympathetic NS helps the body to relax. It maintains body functions like heart rate and digestion. Opposite of the sympathetic.
3
Q
Cerebral Cortex
A
The newest, most advanced part of the brain. Consists of 2 hemispheres that communicate with each other through a corpus callosum. Involves the primary sensory areas and processes with awareness.
4
Q
Limbic System
A
Group of highly specialised neural structures at the top of the brain stem e.g. amygdala, hippocampus. Regulates emotions, hunger, sleep-wake.
5
Q
Cerebellum
A
Aristotle calls it the small brain. Involved in movement and posture unconsciously.
6
Q
Brain Stem
A
Most basic part of the brain, even seen in some less evolved animals. At the top of the spine. Monitors life support functions like breathing and digestion. Also helps with balance, coordination and reflexes.
7
Q
Hemispheres
A
Left hemisphere- language, analytical
Right hemisphere- creativity, visual, intuitive
8
Q
Corpus Callosum
A
Communication between the hemispheres. Bundles of neurons between them.
9
Q
Gyri
A
The folds or bumps in the brain. Made up of grey matter consisting of nerve cell bodies and dendrites.
Cingulate Gyrus- Component of limbic system. The anterior portion has a significant role in processing emotions. Posterior portion handles spatial memory and coordinates movement, orientation, navigation.
Precentral Gyrus- Posterior position of frontal lobe. Contains primary motor cortex.
Superior Temporal Gyrus- Auditory cortex.
10
Q
Sulci
A
The indentations or grooves.
Central sulcus- separates frontal lobe (motor control) from parietal lobe (sensory processing).
Lateral sulcus- separates frontal and parietal lobes from temporal.
Sulci and Gyri are important for increasing volume and the folded appearance helps to maximise surface area of cerebral cortex in limited space. this is particularly important in the frontal lobe.
11
Q
Occipital Lobe
A
Visual processing. Perceiving distance, depth, colour, and movement. Important for recognising objects and faces.
An example: primary visual cortex.
Receives information from retina via the thalamus. Sends information to the parietal lobe and then to the temporal lobe to give meaning to stimuli .
12
Q
Parietal Lobe
A
Somatosensory processing. Touch, pain, temperature, sense of limb position.
Receives sensory information from all over the body. The somatosensory cortex: interprets and discriminates touch sensations e.g. cold v pain. Hearing, visualisation, perception, memory and language.
13
Q
Temporal Lobe
A
Primary Auditory Cortex. Receives information from ears and gives them meaning. Interacts with other structures of limbic system. E.g. amygdala and hippocampus.
Important for language, memory and senses.
14
Q
Frontal Lobe
A
Important for planning including decision making and self-management.
Also important for reward seeking behaviour/delay of gratification, selective attention and empathy. Important for personality due to impulse control and memory. Primary Motor Cortex is important for voluntary movements.
15
Q
Post-mortem dissection
A
When a body is carefully cut open and examined after death to study internal organs and structures.
16
Q
Neuroimaging
A
Techniques used to take pictures of the brain to see its structure and activity. Both structural and fucntional.
17
Q
fMRI- Functional Magnetic Resonance Imaging
A
Measures changes in level of naturally occurring oxygen in blood to map which areas of the brain are more/less active during a task.
18
Q
Positron Emission Tomography (PET)
A
Injects radioactive substance into bloodstream as an indicator of metabolic activity in brain areas.
19
Q
Electroencephalography (EEG)
A
Measures electrical activity at the scalp. Good temporal resolution, but poor spatial resolution.
20
Q
Neurons
A
Functioning:
- Dendrites: they receive input from other neurons via neurotransmitters. This causes electrical changes that are interpreted in the cell body (soma).
- If the signal is strong enough, it is passed on as an action potential down the axon.
- Myelin: helps to stop action potential from degrading.
- Axon terminals receive action potential and release neurotransmitters across the synapse to other dendrites
21
Q
Membrane Potential
A
At rest, inside of the neuron is more negative (-70mV)
Difference in electrical charge between the inside and outside of the neuron.
Develops due to ions in and out of the neuron
22
Q
Action Potential
A
Basis for electrical signalling with neurons.
When dendrites receive input from another neuron (via neurotransmitters) it can cause depolarisation of the neuron. Repeated depolarisation causes the neuron to reach its threshold membrane potential (-55 mV).
23
Q
Depolarisation of a Neuron
A
First step in how a neuron sends a message. When the inside of the neuron becomes less negative for a short time.
Neuron is at rest with the inside more negative than the outside.
Then, stimulus comes in which causes sodium channels to open.
Sodium rushes in with positive sodium ions entering the cell making the inside more positive.
Change in charge- depolarisation.
If the charge is big enough, it triggers an action potential (a nerve impulse).
24
Q
Hyperpolarisation
A
When inside of neuron becomes even more negative than its normal resting state.
Happens right after a neuron has sent a message ie. after action potential. Part of process of neuron resetting itself before it can fire again. After signal, potassium ions leave cell. Sometimes too many potassium ions leave, making inside extra negative. Brief cool down period.
25
Grey Matter
Part of brain and spinal cord that contains most of neurons' cell bodies. Thinking and processing areas. made of neuron cell boidies, dendrites, axon terminals, glial cells.
26
White matter
Part of the brain and spinal cord made up mostly of nerve fibres (axons) that carry messages between different areas of grey mater. made of axons, myelin, glial cells.
27
Myelination
Where myelin, fatty insulating layer, forms around the axons of neurons.
28
Neural Induction
1st Stage in Brain Development.
Day 18-24.
It is genetically determined.
Neural tubes form and ends close. Neural patterning occurs where cells acquire different identities and dimensions. The ectoderm are signalled to become neural tissue, forming the neural plate which then develops into the neural tube (precursor to the brain and spinal cord).
29
Proliferation
2nd stage of brain development.
Day 24-125.
Genetically determined.
250,000 cells produced per minute. By day 125, foetus has all its cells- mid pregnancy.
A single layer of cells called the "ventricular zone" forms along the inner surface of the neural tube.
30
Migration
3rd stage of brain development.
Cells migrate from bottom level towards top level to their final destinations. Radial glial cells act as scaffolding to help cells migrate.
31
Differentiation
4th Stage of brain development.
Day 125- post natal. Cells differentiate into what they will become i.e. hippocampus cell, cerebellum cell. Then a cell starts to express particular genes to make exact proteins it needs i.e. it acquires its distinctive features. Differences in things like protein, neurotransmitter types, receptor subtypes. Transplanted immature cells take on characteristics of new area.
32
Synaptogenesis
5th stage of brain development.
Neurons grow more axons and dendrites, adding synapses.
33
Cell Death/Stabilisation
6th stage of brain development.
Initial surge in synaptic growth levels off and declines after 1st year. Process of cell death can sculpt/prune to bring about balance.
34
Synaptic Rearrangement
7th stage of brain development (last stage).
Early on, axons reach out widely and form a diffuse pattern. Then, adjustments are made. Synapses that are active are strengthened. Synapses that are not are weakened. A more focused pattern of synaptic contact is left.
35
Genetic Determination
Traits, characteristics and behaviours are primarily controlled by our genes.
36
Glial Cells
Non-neuron cells in the nervous system that support, protect, and nourish neurons.
37
Cortical Grey Matter
Outer layer of the brain's cortex. Part of the brain responsible for higher-level functions like thinking, perception, memory, and decision-making. Made mostly of neuron cell bodies. Processes information, rather than sending it long distances. Made of neuron cell bodies, dendrites, glial cells, few myelinated axons.
38
Cortical White Matter
Lies beneath the grey matter in the brain and is made up of mostly myelinated axons- long nerve fibers that carry signals between different parts of the brain and between the brain and body. Acts like the wiring system. Connects areas of grey matter so they can communicate quickly and efficiently.
39
Childhood
Gilmore et al., 2018- Rapid postnatal growth of cortical grey matter over 1st 2 years. Slower growth of cortical white matter throughout childhood and adolescence.
40
From Birth: The first 2 years (Gilmore et al., 2018)
Total brain doubles and reaches 80% adult size by age 2.
Basic structural and functional framework is in place by 2nd year of life.
Brain development after age 2 is characteristic mainly by reorganising and fine-tuning major circuits already established.
41
Adolescence
Developing a more stream-lined brain.
Higher ratio of white matter to grey matter.
Decrease of synaptic connections at dendrites (grey matter).
Synaptic connections are refined to make space for mature patterns to form. This occurs first in occipital/parietal lobes then in the frontal/temporal lobes.
Increase in myelination (white matter).
Myelinated nerves can carry up to 100x faster.
Still developing neural connections.
Functional Connectivity between prefrontal cortex and subcortical structures does not reach stable state until mid 20s.
42
Imbalance Model of Brain Development
Somerville & Casey (2010)
Reward-related subcortical regions and prefrontal control regions interact differently across development.
Motivational and emotional subcortical connections develop earlier than connections supporting prefrontal control. Result: Greater reliance on motivational subcortical regions than on prefrontal regions during adolescence. More reliant on motivation than intrinsic emotion regulation.
43
Environmental Influences on Brain Development: Prenatal Tobacco Exposure
Nicotine is the most prevalent substance used during pregnancy. Toxins in tobacco can cross the placenta barrier. Dampens gene expression of foetal brain regulatory genes responsible for brain growth, myelination and neural migration- alters brain structure and function (Salihu et al., 2017).
44
Environmental Influence on Brain Development: Prenatal Maternal Stress
Foetus exposed to increased maternal cortisol.
Impact on functional and structural amygdyla and PFC and hypothalamic pituitary axis.
These brain changes increase risk for behavioural problems later in life.
45
Environmental Influence on Brain Development: Prenatal Maternal Depression
Associated with increased maternal cortisol (Buss et al., 2012).
Maternal cortisol levels predict larger amygdala in 7 year old children.
Qiu et al., 2015- 6 month old infants born to mothers with higher prenatal depressive symptoms showed greater functional connectivity of the amygdala with key brain regions involved in activation and regulation of emotional states e.g. areas of the PFC. Consistent patterns of connectivity observed in adolescents and adults with major depressive disorder.
46
Environmental influence: Socioeconomic status
Tooley et al., 2021
Higher childhood SES is associated with prolonged structural and functional brain development, leading to more efficient cortical networks in adulthood.
For low SES, greater exposure to chronic stress seems to accelerate brain maturation.
Repeated activation of stress-related circuitry could lead to faster maturation of that circuitry. Stress could cause faster ageing of entire body via increased glucocorticoid levels and allostatic load (physiological wear and tear).
47
Poverty
Hair et al., 2015
Poverty affects mental and physical health and life outcomes through toxic stress.
389 typically developing children/adolescents aged 4-22 years.
Living below poverty: 8-9% reduction in grey matter in frontal and temporal cortex and hippocampus.
Grey matter reductions explained 15-20% of the income-related achievement gap.
48
Changes with ageing
Changes to PFC- retrogenesis (reverse development- as te brain declines it loses functions in the opposite order from how it gained them during childhood).
Grey matter in PFC declines by approx. 5% per decade from age 20 onwards (Raz et al., 2004).
Changes to the hippocampus- Age related decrease in hippocampal volume are associated with decline in multiple areas of cognition (O'Shea et al., 2016) i.e. working memory and episodic memory.
49
Neglect
Perry, 2002
Neglected children had mean frontal-occipital circumference below 5th percentile. Brain size improved when the children were removed from the neglectful environment and reassessed after 1 year in foster care, especially when younger. Shows plasticity of brain. Very resilient.
50
Compensatory Brain Activity
How the brain adapts and reorganises itself to make up for damage, aging or disease. When one brain area becomes less efficient, other areas step in.
51
HAROLD Model
Hemispheric
Asymmetry
Reduction in
Older
Adults
Explains a pattern of compensatory brain activity often seen as people age. Older adults use both sides of their brain (bilateral activity) for tasks that younger adults do with one side. Supports idea of cognitive reserve- the brain can adapt and and stay functional by recruiting new areas. Helps to devise interventions of how to support healthy cognitive ageing. Awareness.
52
PASA Model
Posterior
Anterior
Shift in
Ageing
Describes a pattern where older adults show more brain activity in the front of the brain (anterior) and less activity in the back (posterior). As we age, brain activity tends to shift forward. Posterior regions becomes less efficient as we age. Adaptive brain plasticity.
53
Self control
Ability to resist temptation and override impulsive responses to behave consistently with long term goals (Hassin et al., 2010).
Overriding inhibition of automatic, habitual or innate behaviours, urges, emotions or desires that would otherwise interfere with goal-directed behaviour (Muraven et al., 2006).
54
Prefrontal Cortex
Front part of frontal lobe. Decision-making, self-control, planning, social behaviour and personality. Controlling impulses.
55
Amygdala
Temporal lobe. Plays an important role in emotion processing and regulation.
56
Social Environment
Contexts, external factors that influence social situations and your behaviours.
57
Mid-Superior Temporal Sulcus
Region in the temporal lobe of the brain. Located along the superior temporal sulcus. Important for social perception.
58
Positive Life Outcomes
Self-control predicts positive life outcomes. Mental health, psychological well being, interpersonal relationships. Personal and societal costs of failures at self-control. Alcohol and substance addiction, debt, physical problems e.g. obesity.
59
Top Down Processing
Abstract, rational, goal-directed behaviour. Involves cerebral cortex, PFC, especially lateral PFC.
60
Bottom Up Processing
Reflexive, environmentally triggered, emotionally driven behaviours. More primitive structures- brain stem, limbic system.
61
Cerebral Cortex
Outermost layer of the brain. "Thinking cap". Responsible for most of our complex mental functions like perception, language etc.
62
Dorsolateral PFC
In PFC. Region involved in higher-level thinking. Brain's executive assistant. Helps you plan, focus, regulate behaviour and self-control.
63
Ventral Tegmental Area
Midbrain. Reward system, produced dopamine. Dopamine is linked to pleasure, motivation, learning and addiction.
64
Basal Ganglia
Helps control and choose movements, form habits and process rewards. No need for conscious effort.
65
Nucleus Accumbens
Key brain area for reward, motivation, pleasure and reinforcement learning. Helps you feel good, want things and learn what is rewarding. drives motivation and goal-directed behaviour.
66
Ventral Striatum
Region involved in reward, motivation and emotion related decision making. Components: Nucleus Accumbens and Olfactory Tubercle.
67
Limbic System
Emotional nervous system. Manages emotions and motivations.
68
Self regulation
How the brain and body work together to manage emotions, behaviours, thoughts and physiological responses.
Successful Self regulation- top down control from the prefrontal cortex over subcortical regions involved in reward and threat processing.
Self regulatory failure- top down control is diminished or when the balance in activity favours threat and reward systems.
69
Balance Model of Self Control
Lopez et al., 2017
Not about resisting temptations, but about managing goal conflicts and keeping balance between immediate desires and long term priorities.
70
Brain Structure and Self Control (Kim et al., 2020)
Dietary self control
Structural MRI scans of cortical thickness and volume.
Thinner cortical thickness of PFC predicted lower dietary self-control.
Higher volume of amygdala predicted lower dietary self-control.
71
Anandakumar et al., 2018- brain patterns associated with self control and rewards.
Resting state fMRI.
Greater connectivity between cortical regions within cognitive control systems- more likely to choose larger later rewards.
Greater connectivity with limbic system- more likely to choose smaller-sooner rewards.
72
Cognitive Control over Temptation (Kober et al., 2010)
fMRI while using cognitive strategies to regulate cravings for cigarettes and food images. Cognitive strategy: think about the long term consequences of repeatedly consuming the item. This significantly reduced cravings. Associated with increased activity in the PFC. Decreased activity in the ventral striatum, amygdala and ventral tegmental area.
Suggests that control increases and impulsivity decreases. Consciously being aware of long term consequences reduces impulsivity and increases delay of gratification.
73
McDonald et al. 2017- Lesions and Impulsivity
Damage to PFC is associated with increased impulsivity. Supports Kober et al.
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Impulsivity
Behaviour driven by immediate urges, and executed without thoughtful deliberation or appropriate regard to consequences.
75
Limitations of Lesion Studies
Different areas are affected in different individuals.
Possibility of functional reorganisation following injury.
76
rTMS
Repetitive Transcranial Magnetic Stimulation.
Low frequency rTMS decreases excitability and creates a temporary lesion effect.
77
tDCS
Transcranial Direct Current Stimulation
Electrodes positioned on the scalp over cortical regions of interest. Modifies spontaneous neuronal excitability by changing neurons resting membrane potentials.
78
tDCS and Risk-Taking, Gilmore et al., 2017
Participants choose whether a token is hidden in a red/blue box. Less likely option has higher reward (riskier choice). tDCS- activate right dorsolateral PFC twice a day for 5 days. tDCS group made less risky choices- less impulsive.
79
tDCS and Inhibition, Nejati et al., 2018
Measured inhibition using a go/no go task.
Activated left dlpfc with tDCS. Increased accuracy on no go answers. Increased reaction time. More thoughtful processing. Top down control.
80
Marshmallow Test
Mischel's test of delay of gratification.
Casey et al., 2011.
40 years later, task requiring inhibitory control as adults. Those successful in delaying gratification as children preferentially recruited PFC as adults. Those unsuccessful = ventral striatum.
81
Adolescence and reward seeking behaviour
In the past, adolescent reward seeking and risk taking behaviour due to an underdeveloped PFC. However, children also do not have a mature PFC and do not display the same risk taking as adolescents.
Now, models consider circuitry and how different brain regions interact
82
Dosenbach et al., 2010- adolescence and neural connections
Functional connectivity between PFC and subcortical structures does not reach a stable state until the mid 20s.
83
Imbalance Model of Brain Development- Somerville and Casey (2010)
Across development, reward related regions and prefrontal control regions interact differently.
Motivational and emotional connections develop earlier than connections supporting control.
Result: greater reliance on motivational subcortical regions than on prefrontal regions during adolescence.
84
The Social Brain
Regions involved in social cognition:
- Medial prefrontal cortex
- Temporoparietal junction
(involved in thinking about mental states)
- Posterior Temporal Sulcus (activated by observing faces and biological motion)
- Inferior Frontal Gyrus
- Interparietal Sulcus
- Amygdala
- Anterior Cingulate Cortex
- Anterior Insula
85
Sallet et al. 2011- Social environments affect our brain
Macaques living in larger social groups had larger volumes in mid-superior temporal sulcus and rostral PFC.
86
Amygdala in the Social Brain
Amygdala is a hub for the social brain with connections to other relevant cortical and subcortical regions. (Bickart et al., 2014).
87
Perception Network
Performing the sensory processes involved in detecting, decoding and interpreting social signals from others in the context of past experience and current goals (Bickart et al., 2014).
88
Ventrolateral Amygdala and Lateral Orbitofrontal Cortex
In the perception network, they receive input from sensory association areas of the temporal cortex, activated when responding to socially salient stimuli e.g. facial expressions and identity.
89
Structural Differences in Social Brain
In perception network, pateitns with impaired perception of facial expression and sarcasm comprehension have structural differences in amygdala, lateral orbitofrontal cortex and temporal pole.
90
Affiliation Network
Important for the processes associated with motivating prosocial or affiliative behaviours, like comforting a loved one in distress (Bickart et al., 2014).
Nuclei in medial amygdala and ventromedial prefrontal cortex connect to subgenual anterior cingulate cortex and ventromedial striatum.
91
How does Affiliation Network operate?
Regions in this network respond to pictures of loved ones and positive social deedback and motivate decisions to behave altruistically.
Decreased grey matter in ventromedial prefrontal cortex and anterior cingulate cortex associated with diminshed empathy and interpersonal warmth.
92
Aversion Network
Important for the processes enabling avoidant behaviours like avoiding an untrustworthy appearing stranger.
93
How does Aversion Network operate?
Nuclei in rostrodorsal amygdala and caudal anterior cingulate cortex connect to pain-sensitive targets.
Regions in this network respond to untrustworthy faces and negative social feedback that elicit social aversion and motivate decisions not to cooperate.
Frontotemporal dementia patients with atrophy in this network were more willing to trust strangers and more likely to fall for scams.
94
Empathy
Natural capacity to share, understand, and respond with care to the affective states of others- Decety, 2012.
95
Singer et al., 2004- Empathy for Pain
fMRI administered to the participant. Higher empathy score = stronger activation in anterior cingulate cortex and anterior insula. Associated with Affiliation Network.
96
Empathy & Cognitive Appraisal
Lamm et al., 2007, 2010
Empathic pain-related responses in anterior insula and anterior cingulate cortex (even when the target was not in pain).
Activation in network for self-other distinction (tempoparietal junction) and cognitive control (inferior frontal cortex).
97
Vicarious Embarassment/Second hand embarassment
Melchers et al, 2015. Observing social norm violations.
Vicarious embarassment activated regions associated with:
- Empathic concern (anterior cingulate cortex)
- Theory of Mind (middle temporal gyrus)
- Social identity (inferior frontal gyrus)
98
Psychological Altruism
A reaction to the signals and situation of another individual and involves an attempt to alleviate the other's negative state, in the absence of any clear, immediate benefit to the self. Preston & de Waal, 2011).
99
Altruistic vs Strategic Choices
Cutler & Campbell-Meiklejohn, 2019
fMRI meta-analysis.
Altruistic= no extrinsic reward, but intrinsic satisfaction.
Strategic= Extrinsic reward e.g. reciprocity
Both types of giving choices activate:
- Nucleus Accumbens
- Anterior Cingulate Cortex
-Ventromedial PFC
BUT
Altrusitc more strongly activates:
- Subgenial ACC which activates charitable donations, distinguishes altruism frm decisions with benefits for the individual.
Strategic more strongly activates:
- Nucleus Accumbens
100
Neuroscience of Likes (Sherman et al., 2018)
fMRI of adolescents & young adults
Reward circuits (e.g. striatum, ventral tegmental area) activated by giving and receiving likes on Instagram.
101
Abstract Social Thought (Gotlieb et al., 2021)
Asolescents' ability to interpret and react emotionally to social information becomes more sophisticated.
Activity in Default Mode Network predicted abstract construals i.e. dorsomedial and ventromedial PFCs and inferior/posterior posteromedial cortices. Active when we are daydreaming/imagining.
102
Social Exclusion (Masten et al., 2009)
Higher distress during exclusion associated with increased activity in insula (involved in physical pain) and subgenual anterior cingulate cortex (subACC; contrary to adults).
103
Interpersonal Competence in Adolescence
More conscious of peer norms and influence.
104
What is stress?
Stress is a response to any demand or threat- real or perceived. Physical and psychological reaction.
It can also be a stimulus. Views stress as something that happens to you.
Combination: A transation between the individual and their environment.
105
Pathways in the NS involved in the stress response
Autonomic Nervous System
- Sympathetic
- Parasympathetic
106
Sympathetic
Fight or flight
Rapid burst of energy to respond to perceived danger.
107
Parasympathetic
Rest and digest
Calms the body down after the danger has passed.
108
Sympathetic stress response
Amygdala sends distress signal to hypothalamus.
Hypothalamus sends signals through autonomic nerves to adrenal glands.
Adrenal glands release epinephrine (adrenaline) into bloodstream.
Adrenaline circulates through the body and produces physiological changes.
109
Fight or Flight Response
Evolutionary survival mechanism for physical danger.
Now also activated by psychological or emotional stressors.
Useful for: predators
Less helpful for: public speaking
110
HPA Axis- Hypothalamic Pituitary-Adrenal Axis
Hormonal System: Hypothalamus releases corticotropin-releasing hormone (CRH)
Pituitary gland releases adrenocorticotropic hormone.
Adrenal glands release glucocorticoids e.g. cortisol.
Peak levels after 15-30 minutes.
111
Parasympathetic nervous system response
Triggers the necessary responses to return to homeostasis (maintenance of a stable internal environment).
112
Transactional Model of Stress
Stress is an interaction between the person and the environment.
Stress responses (cognitive, physiological + behavioural) are evoked when there is a perceived imbalance between situational demands and personal resources.
The stress response depends on how that individual interprets (appraises) a particular external stressor.
113
Interpreting Stressors: Cognitive Appraisal
How a situation is first evaluated and interpreted.
Primary appraisal: is the stimulus harmful? is this a threat or a challenge?
Secondary appraisal: is this within my coping abilities? how can I deal with the situation to get a positive outcome?
114
Cognitive Reappraisal
Rethink or reinterpret a situation in order to change its emotional impact. Changes the meaning of the situation.
115
Appraisal and Stress- Dickerson & Kemeny, 2004
Tasks that were appraised as being out of one's control and having a social-evaluative threat increased cortisol the most.
116
Controllability & Threat-Related Activation
Limbachia et al. (2021)
- Threat-related regions showed lower activation when participants had control over the stressor. Our appraisals of a stressor (controllable or uncontrollable) affect our brain activation responses.
117
Appraisal & Somatic Symptoms- Szabo et al., 2016
Somatic symptoms- Physical symptoms like pain, fatigue, or dizziness. Often linked to psychological factors.
Threat positively associated with somatic symptoms.
Challenge negatively associated with somatic symptoms.
118
Physiological impacts of acute stress
Impairs prefrontal cortex and performance of tasks that require complex, flexible thinking.
Enhances amygdala and hippocampus function and performance of simple, well-rehearsed tasks.
119
Acute Stress
Body's immediate reaction.
Short term stress.
Usually resolves once the situation is over.
120
Amygdala Control (Stress)
Stress impairs PFC regulation and strengthens amygdala function.
Attention regulation switches from 'top-down' (most relevant) to 'bottom-up' (sensory salience).
Brain response pattern switches from slow, thoughtful PFC regulation to reflexive, rapid emotional responses of amygdala.
121
Chronic Stress remodels PFC Neurons
Radley et al. 2004
Chronic stress resulted in decreased dendrite length in PFC in rates.
122
Chronic Stress
Long-term, ongoing form of stress. persists over weeks, months or even years.
123
Chronic Stress Remodels Amygdala neurons
Vyas et al. 2002
Chronic stress (immobilisation) in rats results in increased dendrite length in amygdala.
124
Allostasis
Body's process of achieving internal stability by actively adjusting stressors, demands and environmental changes. Like homoestasis but more flexible and dynamic.
125
Allostatic Load/Overload
Long-term effects on the body of continued exposure to stress.
126
Acute v Chronic
Dhabhar, 2009
Acute stress enhances immune function. Chronic stress suppresses immune function.
127
Chronic Stress & Memory (Chen et al., 2019)
Chronic stress impairs prospective memory (remembering to perform a planned action).
Participants performed poorer on a prospective memory task in chronic stress (exams vs baseline).
128
Racial Discrimination as Chronic Stressor
Racial discrimination as a psychosocial stressor:
- Discrimination and social exclusion provoke stress response, having detrimental effects on health.
Increased blood pressure and cortisol.
129
Racial Discrimination & ACC
ACC activated by social exclusion.
130
Racial Discrimination & PFC
Ventral PFC involved in top-down regulation of stress during social rejection. Racial discrimination activates brain regions involved in social distress and reduces activity in regions involved in emotion regulation.
131
PTSD
Exposure to traumatic event followed by dev. of a range of symptoms:
- Re-experiencing
- Hyperarousal e.g. vigilance or exagerated startle response
- Avoidance behaviour
Higher PTSD Symptos, higher activation of amygdala in response to threat.3
132
Biological Processes regulating sleep and wake
Circadian rhythm- 24 hour internal body clock.
Sleep Homeostasis- regulates sleep pressure.
133
Circadian Rhythm
PROCESS C
Controlled by the SCN (suprachiasmatic nucleus) in the hypothalamus. Sensitive to light vis the retinohypothalamic tract. Helps synchronise bodily processes like melatonin secreation, body temp, reaction time and hormone cycles (e.g. cortisol).
Circadian triggers:
Evening- Melatonin increases
Night- Core body temp drops
Morning- cortisol surges- wake up and feel alert
Daytime- alertness and physical performance peak
Driven by light, internal clock.
134
Sleep Homeostasis
PROCESS S
Regulates sleep pressure- the longer you are awake, the stronger the drive to sleep.
During wakefulness, adenosine accumulates in the brain. It makes you feel sleepy. Sleep clears out adenosine, resetting the drive.
Controls how much sleep you need.
135
Neurochemicals and Hormones involved in sleep
Cortisol- promotes wakefulness, peaks in the morning
Adenosine- builds sleep pressure, promotes sleep
GABA- inhibitory neurotransmitter, calms brain
Orexin- maintains wakefulness and alertness
Serotonin- helps initiate sleep, mood regulation
Acetylcholine- increases during REM sleep
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Brain Structures regulating sleep-wake cycles
SCN- master circadian clock
Pineal gland- releases melatonin
Hypothalamus- monitors sleep need, regulates hormones
Brainstem- promotes arousal and REM transitions
Basal Forebrain- involved in adenosine regulation
Thalamus- regulates sensory signals during sleep
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REM Sleep- Rapid Eye Movement
Occurs approx. 90 mins after sleep onset.
Brain activity increases but body is paralysed.
Most dreaming happens hear.
Important for emotional regulation, learning and memory
Cycle through these stages 4-6 times per night.
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Measuring Sleep
Polysomnography
Records multiple body functions, usually through sensors placed on the body.
Used to understand sleep, detect disorders and guide treatment.
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SCN
Specialised group of hypothalamic cells.
Receives information about light exposure from ganglion cells in retina.
Activates melatonin secretion by pineal gland.
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Zeitgebers
External environmental cues that help synchronise your internal circadian rhythms with the 24 hour day. The SCN needs external zeitgebers to keep circadian rhythms aligned with outside world. I.e. Light= most powerful zeitgeber.
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Endogenous Pacemakers
Main: SCN
Biological clock inside body. Does not need external cues.
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Circadian Preference
An individual's natural inclination for wakefulness and sleep timing.
i.e. morning, evening, intermediate (midday)
Biological factors, environmental influences.
Mismatch between chronotype and external demands can lead to: social jetlag, sleep deprivation, mood disorders, lower academic/work performance.
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Social Jetlag
When body clock fights social clock.
Mismatch between biological circadian rhythm (chronotype) and social obligations. Jetlag without travel.
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Perfect Storm Model
Carskadon (2011, 2018)
Explains why teenagers often struggle with sleep. It is a biopsychosocial model showing how biological, psychological and social factors collide, creating the "perfect storm" for poor sleep during adolescence.
Result of natural biological shifts, amplified by social and psychological stressors.
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Bioregulatory Pressure
Biological forces that regulate when you feel sleepy or alert.
Internal balance between circadian rythm and sleep need.
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Developmental Changes in Circadian Rhythms
Circadian phase delays across puberty.
Adolescence: melatonin delay, homeostatic pressure, social pressure. Perfect storm.
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Changes to Sleep Pressure
Sleep pressure dissipates at same rate.
Total sleep need does not change.
But sleep pressure builds slower.
Therefore waking day is extended, permits later bedtime.
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Psychosocial Pressure
Bedtime autonomy: parental set bedtimes associated with earlier sleep onset & longer sleep duration.
Academic pressure
Screentime and social media
Psychosical & bioregulatory pressures interact.
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Circadian Misalignment
Insufficient sleep + state of social jet lag.
REM important for emotional regulation.
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Sleep, Mood, Anxiety
Bidirectional relationship: mood disorders, sleep problems.
Short sleep duration & insomnia symptoms linked to suicidal ideation.
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Shift Work Sleep Disorder
Sleep disorder that affects people who frequently alternate shifts or work at night, contrary to the body's natural circadian rythm.
Most successful work shedules involve shifts that move gradually clockwise, rather than shifts that change irregularly and quickly.
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Psychomotor Vigilence Test
Sustained attention task.
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Health Belief Model
Assumes that health behaviour results from the desire to avoid (or recover from) illness and belief that a specific health behaviour will prevent (or cure) illness.
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Health Behaviour
Behaviours performed by individuals to protect, promote, or maintain their health, or to detect or avoid illness.
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Perceived Susceptibility
Construct of the HBM.
A person's belief about how likely they are to get a disease or experience a health problem.
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Perceived Severity
Construct of HBM.
An individual's belief about how serious a health condition and its consequences would be.
If you think you are at risk, how much does it matter to you?
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Perceived Benefits
Construct of HBM.
A person's belief in the effectiveness of a health action to reduce the risk or severity of a disease or condition.
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Perceived Barriers
Person's beliefs about the obstacles to performing a health behaviour.
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Non-Health Beliefs
Health-related beliefs are not the only relevant motivations that can influence health behaviours.
Perceived social norms and attitudes influence behaviour too.
External, as well as internal.
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Theory of Reasoned Action
Explains how people form intentions to perform certain behaviours- especially health-related.
Fishbein & Azjen (1975)
Behaviour is primarily driven by intention and this intention is shaped by attitudes and social norms.
Behavioural beliefs and attitude towards behaviour, as well as normative beliefs and subjective norms lead to an intention which lead to a behaviour.
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Falk et al., 2010- intentions, suncream use
Participants viewed slides on importance of suncream use. Participants then reported their behaviour, intentions and attitudes towards suncream before and 1 week after. The following week, participants used suncream on more days.
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Critique of Theory of Reasoned Action
Model assumes that intention is the most important influence on behaviour. Does not account for:
- Not every behaviour is equally under out control
- Behaviours require more than just will
- Behaviours require skills, resources, opportunity
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Self-Efficacy
Belief in your own ability to successfully perform a specific behaviour or task. Plays a central role in whether people start, maintain and succeed at health behaviours.
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Perceived Behavioural Control
Overlaps with construct of self-efficacy.
How easy or difficult it is to perform a particular behaviour.
Behaviour can be predicted by this notion.
Influenced by past experiences and anticipated obstacles.
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Intention-Behaviour Gap
Saying we will do something and then we don't. Intention does not always equal action. Due to many things including:
- Lack of self-efficacy
- Poor planning
- Environmental barriers (time, money)
- Habits/automatic behaviours (old routines overriding good intentions)
- Low motivation
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Transtheoretical Model (Stages of Change)
Developed in late 1970s by Prochaskia & DiClemente
Wanted to understand why some people were able to quit smoking on their own whereas others required more support.
Explains how people change behaviour over time.
Breaks behaviour change into 6 changes:
- Precontemplation (person is not considering change)
- Contemplation (i might change)
- Preparation (planning to change soon)
- Action ( actively doing something)
- Maintanence
- Relapse
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Motivation to Change- Cocaine Use (Prisciandaro et al., 2012)
Participants not seeking tratment (less motivated to change) showed increased activation to cocaine cues in areas like dorsolateral PFC- involved in cognitive control including decisions requiring response inhibition.
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Eagerness Scale
Motivation measurement.
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Vegetative State (VS)
If repeated examinations yield no evidence of a sustained, reproducible, purposeful, or voluntary behavioural response to visual, auditory, tactile or noxious stimuli, a diagnosis of a vegetative state- or wakefulness without awareness- is made. (Monti et al., 2010)
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Minimally Conscious State
Patients show inconsistent, but reproducible evidence of awareness of themselves and their environment, in as much as they can exhibit sustained, reproducible or voluntary behavioural responses to sensory stimulation. (Monti et al., 2009)
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Distinguishing VS from MCS
Awareness.
40% misdiagnosis rate of MCS mistaken for VS.
Major challenge: assessing level of preserved cognitive function.
Neuroimaging allows exploration of brain responses to reveal hidden cognitive capacity in behaviourally non-responsive patients.
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Identifying covert cognition with fMRI- Boly et al. (2007)
Spatial navigation and motor imagery tasks could be distinguished. 100% accuracy when differentiating patterns of activation between rest, spatial navigation and motor imagery for all subjects. These brain responses are indicative of awareness, thus fMRI responses can be used to measure awareness.
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Owen et al., 2006- VS or MCS
23 year old woman with severe traumatic brain injury from road traffic accident. After 5 months remained unresponsive and fulfilled the criteria for VS. fMRI scan while performing mental imagery tasks showed activation in cortical areas. Her cooperation with authors by imagining particular tasks when asked to do so represents a clear act of intention. Consciously aware.
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Monti et al. 2010- vegetative state?
fMRI used to evaluate 54 patients with a diagnosis of being in a vegetative state. 5 patients could willfully modulate their brain activity. Two patients showed no signs of awareness.
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Identifying covert cognition with EEG
Cruse et al. (2011)- 16 diagnosed vegetative state patients and 12 healthy controls
Looked for EEG evidence of command following as a clinical indicator of awareness. Complex tasks required several aspects of top-down cognitive control: sustained attention, language comprehension, working memory and response selection. Suggests conscious awareness.
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Limitation of fMRI for identifying VS and MCS
Physical stress of transferring patient to an fMRI facility.
Movement artefacts in imaging data from patients who are unable to stay still.
Metal implants are common in traumatically injured populations and rule out fMRI.
EEG is cheaper, unaffected by metal implants and can be used at bedside.
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Implications of evaluating covert cognition in VS patients
Improved diagnosis- fMRI and EEG evidence of awareness can determine if a diagnosis is correct or not.
Term nonbehavioural minimally conscious state has been suggested now. However, some of the complex cognitive capabilities carried out like language comprehension, Owen et al. argue that minimally conscious does not adequately describe.
Decision-Making- neuroimaging may increase opportunities for communication in behaviourally non-responsible patients with covert awareness, potentially allowing them to participate in quality of life decisions.
