Heart Activity and Behaviour

Question 1

•Anatomy and physiology of heart\

Answer 1

Cardiac Cycle- Control of Heartbeat

• Heartbeat (cardiac cycle) represent = contraction heart to pump into circulation
• Average heart rate= 72 bpm
• Heart activity is controlled both internally and externally
• Internal cardiac control = by a system of specialised fibers: SA node, Av node, atrioventricular bundle, left and right bundle of conducting fibres (purkinje fibres)

SA Node

• SA node is pacemaker of heart
• Regular discharges from pacemaker results in rhythmic contraction of heart. Rate of 120 bpm
• Regulated by vagus nerve (10th cranial nerve) to produce 70-80 bpm

Conduction system

•Systole- contraction, Diastole- relaxation phase

External Cardiac Control

• ECC mainly controlled by ANS and CNS
• ANS: parasympathetic NS ( vagus nerve- result in decrease in heart rate- negative chronotropic effect), sympathetic NS- release norepinephrine- result increases in heart rate (positive chronotropic effect)

Heart Regulation by CNS

• CNS also controls activity and contraction of heart
• In past medulla known to exert primary control over certain reflex actions concerned with controlling HR, however other CNS structures shown to exert control: hypothalamus, amygdala and cerebellum

Baroreceptors

• Are pressure sensitive fibres present in carotid sinus
• Involved in carotid sinus reflex
• Baroreceptors ensure adequate blood supply to brain by monitoring BP

Cardiac Sinus Reflex

Cardiac Muscle

• Contraction mediated by cardiac muscle (autorhythmic) cells
• Cardiac muscles= short, branched and striated each fibre may contain 1-2 nuclei
• Gap junctions- join cardiac cells. Allow ions to move between auto rhythmic cells and between muscle cells

Question 2

•Conduction system and cardiac action potential

Answer 2

Molecular level- generation of action potentials

•Electrical potential from SA node is initiated from influx NA 2+ ions→ depolarisation due to Ca2+ influx and repolarisation due to K+ efflux

Question 3

ECG

Answer 3

• Method to record electrical discharges degenerated from heart
• Several deflections- form a waveform
• Waveform- composed of P, Q, R, S, T waves
• P waves start as fraction of a second before atria contract= atrial depolarisation
• QRS wave is caused by spread of excitation through ventricles= ventricular depolarisation
• T waves= restoration/ relaxation (repolarisation of ventricles)

Question 4

•Cardiac measures in research

Answer 4

Cardiac Measures in Research

•Variables recorded in research: HR ( number of bpm based on R wave), Interbeat Interval (IBI- time between R waves)

Impedance Cardiography

• Measure used in research to assess physical functions of heart
• Cardiac output: amount of blood pumped in L/min
• Stroke volume- amount blood pumped/ beat
• Ventricular Ejection Time
• Myocardial contractility
• Total peripheral resistance- resistance to blood flow in body

Behaviour and HR

• HR can decrease/ increase in response to task
• HR deceleration is related to stimulus intake and orientation
• HR acceleration involved in stimulus rejection and defensiveness

Heart activity and Behaviour studies

•Cardiac activity measured in relation to: development, performance, motor performance (eg. reaction time), cognition (learning)

Heart Activity and Developmental studies

• Measurement of fetal HR prior to delivery is common method. Monitoring heart activity/rate show decrease in HR when infants get older
• High RSA correlated = greater reactivity to positive and negative stimuli
• Young infants show HR deceleration of 2-4 bpm when auditory or visual stimulation terminated or began
• Shy infants (4 months) show larger HR and BP increases to stress- these children more likely to become fearful later on

Heart activity and Reaction Time Tasks (RT)

• RT studies widely established that having fixed foreperiod during tasks resulted in HR deceleration
• Establishing random foreperiod or no warning signals during RT tasks hwo no HR deceleration
• Magnitude of HR deceleration during preparatory period of RT task, depend on stage of cardiac cycle. ( when RT responses occurred early enough in cycle, deceleration ended and shifted to acceleration with the same heartbeat)
• HR deceleration during RT tasks was attributed to the inhibitory effect of the vagus nerve

Heart Activity & Motor Performance

• HR increases in individuals were observed in motor performance studies
• HR increases during performance were at a level that is greater than what’s metabolically required
• Emotional impact of performing psychologically stressful tasks is not masked by physical activity
• Habituation of HR was shown during driving over 5 days- as a skill for particular task increases, hR is reduced

Heart Activity & Learning

In verbal learning

• HR increases were observed in individual during acquisition phase of verbal learning
• Continued repetition of familiar materials will result in habituation of HR response

In problem solving

• HR decrease= during task requiring mental intake
• HR increases= shown during mental elaboration of problem solving tasks

In imagery studies

• Imagery with emotional association led to significant HR increases than non emotional charged imagery
• Individuals described as having exaggerated health concerns show high HR and longer recovery time when imagining illness compared to the control

Heart Activity and Perception

Perceptual threshold

• General cardiac deceleration accompanied by increased sensory acuity
• Greater HR deceleration found when stimulus perceived than when it was not
• Degree of sensitivity to environment can be predicted by observing cardiac activity

Stimulus Significance

• Complex cardiac response with 70 dB auditory stimuli- decrease → increase→ decrease HR
• Higher intensity resulted in biphasic effect: increase→ decrease HR
• Intensity is high: HR acceleration in first few seconds of stimulus onset. Intensity is low (gradual): delay in HR acceleration
• HR responses to meaning of stimulus eg. auditory signals during dental drills
• Individuals who less familiar with stimulus with specificity intensity showed higher HR acceleration
• Familiar individuals had small HR acceleration

Heart Activity, Attention and Orienting Response

• Studies performed using different stimulus: low vs high intensity sounds, phobic and non phobic stimulus, correlation of H deceleration with eye bursts in REM sleep
• HR deceleration has been associated with stimulus intake and orienting response
• HR acceleration accompanies stimulus rejection and the defensive response

Question 5

Behavioural studies

Answer 5

Behaviour and HR

• HR can decrease/ increase in response to task
• HR deceleration is related to stimulus intake and orientation
• HR acceleration involved in stimulus rejection and defensiveness

Heart activity and Behaviour studies

•Cardiac activity measured in relation to: development, performance, motor performance (eg. reaction time), cognition (learning)

Heart Activity and Developmental studies

• Measurement of fetal HR prior to delivery is common method. Monitoring heart activity/rate show decrease in HR when infants get older
• High RSA correlated = greater reactivity to positive and negative stimuli
• Young infants show HR deceleration of 2-4 bpm when auditory or visual stimulation terminated or began
• Shy infants (4 months) show larger HR and BP increases to stress- these children more likely to become fearful later on

Heart activity and Reaction Time Tasks (RT)

• RT studies widely established that having fixed foreperiod during tasks resulted in HR deceleration
• Establishing random foreperiod or no warning signals during RT tasks hwo no HR deceleration
• Magnitude of HR deceleration during preparatory period of RT task, depend on stage of cardiac cycle. ( when RT responses occurred early enough in cycle, deceleration ended and shifted to acceleration with the same heartbeat)
• HR deceleration during RT tasks was attributed to the inhibitory effect of the vagus nerve

Heart Activity & Motor Performance

• HR increases in individuals were observed in motor performance studies
• HR increases during performance were at a level that is greater than what’s metabolically required
• Emotional impact of performing psychologically stressful tasks is not masked by physical activity
• Habituation of HR was shown during driving over 5 days- as a skill for particular task increases, hR is reduced

Heart Activity & Learning

In verbal learning

• HR increases were observed in individual during acquisition phase of verbal learning
• Continued repetition of familiar materials will result in habituation of HR response

In problem solving

• HR decrease= during task requiring mental intake
• HR increases= shown during mental elaboration of problem solving tasks

In imagery studies

• Imagery with emotional association led to significant HR increases than non emotional charged imagery
• Individuals described as having exaggerated health concerns show high HR and longer recovery time when imagining illness compared to the control

Heart Activity and Perception

Perceptual threshold

• General cardiac deceleration accompanied by increased sensory acuity
• Greater HR deceleration found when stimulus perceived than when it was not
• Degree of sensitivity to environment can be predicted by observing cardiac activity

Stimulus Significance

• Complex cardiac response with 70 dB auditory stimuli- decrease → increase→ decrease HR
• Higher intensity resulted in biphasic effect: increase→ decrease HR
• Intensity is high: HR acceleration in first few seconds of stimulus onset. Intensity is low (gradual): delay in HR acceleration
• HR responses to meaning of stimulus eg. auditory signals during dental drills
• Individuals who less familiar with stimulus with specificity intensity showed higher HR acceleration
• Familiar individuals had small HR acceleration

Heart Activity, Attention and Orienting Response

• Studies performed using different stimulus: low vs high intensity sounds, phobic and non phobic stimulus, correlation of H deceleration with eye bursts in REM sleep
• HR deceleration has been associated with stimulus intake and orienting response
• HR acceleration accompanies stimulus rejection and the defensive response

Question 6

•Heart activity & affective processes

Answer 6

• Stimulus that likely produce emotional reaction in individuals
• Factors that qualify as affective processes: stressors, fear, anger, frustration, competition, motivation

Question 7

•Cardiovascular reactivity

Answer 7

Cardiovascular Reactivity (CVR)

• Magnitude and patterns of cardiovascular responses from baseline to task levels or after exposure to stressors
• Research in CVR mainly linked to development of cardiovascular disease (CHD or hypertension)- reactivity hypothesis
• Sherwood and Turner 1992: HR and BP, individuals have differences in CVR
• Relationship between CVR to long term exposure (job strain)
• Introduction of stress buffers reduced CVR and incidence of cardiovascular disease (social support, relaxation)

CVR Studies

•Genetic and environmental, personality, hypertension, emotion (hostility and anger)

Genetics and Environment

• Light (2001)- gene and modulated reactivity hypothesis
• Increase in CVR using animal models- source of genetic susceptibility or environmental factors
• Genetic link between elevated CVR from stress to development of mild hypertension 97 fold)
• Low CVR subjects only show 2 fold increase in risk of developing hypertension

Personality

• Personality of subjects classified
• Type A: dominance, impatient, competitive and hostile
• Type B: calm, relaxed, patient and showed no aggressive drive
• Individuals were classified into type A and B through a structured interview and the Jenkins activity survey

Jenkins activity survey questionnaire document containing questions:

• Has your spouse or friend ever told you that you eat too fast?
• When you have to wait in line at a store what do you do?
• Do you ever set deadlines or quotas for yourself at work or home?

Personality and CVR studies:

• Relationship between type A/B personalities to changes in HR and BP
• Type A mainly associated with increased cardiovascular activity (HR and BP ) compared to type B in an engaged task
• Relationship is dependant on tasks involved, competitive tasks vs non competitive

Parental History of Hypertension

• Parental history of hypertension also linked with increased CVR
• Increases in CVR: motor tasks (physical activity), cognitive tasks

Emotion (Anger and Hostility)

• Anger and hostility has been shown to correlate with incidence of CHD
• Excessive SNS activation during emotional state
• Suarez and Williams 1989: high vs low hostility, CVR assessed after harass subjects that provoke anger and irritation, exaggeration CVR found in hostile individuals compared to non hostile

Question 8

•Social factors

Answer 8

Social Support & Coping

• Obtrist et al 1978- active vs passive coping
• Being able to influence. Control stressor is active copine
• Passive- not being able to influence or control stressor
• Individual who exert active coping showed higher CVR than those passive coping
• Social support has been postulated to be buffering factor in CVR
• Kamark et al 1990: 2 tasks (mental arithmetic and cognitive formation) was performed by college students. In presence of fried support, significantly lowered CVR, subject alone had 2 fold magnitude in CVR (mental arithmetic)
• Steptoe (2000): introduction of social support in real life situation, effect of everyday stress in working lives school teachers (high vs low support group), reduced CVR readings in high social support group that shows buffering of everyday stress

Question 9

•Brain and heart interactions

Answer 9

Interactions between heart and brain activity

• Brain play role in regulating heart activity
• Evidence also show influence cardiac activity change brain activity
• Walker and Sandman 1979: measured evoked brain potentials to light flashed when HR low, moderate and high. P2/ P2oo component in visual ERP (right hemisphere) was larger at lower HR. this indicates sensitivity of right hemisphere in cardiac changes

CNS and Heart Activity

• Contingent negative variability (CNV) is long duration brain response that slowly develop between a, warning stimulus (S1) and required response (S2)
• This can be seen in slowing of HR during fixed fore period during RT tasks
• Friedman and colleagues: interested in link between CNV and heart activity using mental RT tasks in all age groups. Found the relationship between CNV and heart activity

Question 10

Conditioning of heart activity

Answer 10

Classical Conditioning

• A behavioural paradigm presented by Pavlov (1920)
• There is a conditioned response (CR) after presenting of conditioned stimulus (CS) that was paired with unconditioned stimulus (UCS)
• CS is usually neutral stimulus- does not elicit any behavioural response
• However pairing it with and UCS alklos CS to form association with UCS

Pavlove 1920

• In early stages: CS (bell) paired with UCS (food) presented to doh. → resulted in an UCR through salivation
• During final stages of conditioning: CS (bell) without the UCS can elicit a response (CR) through salivation
• Notterman et al (1952: used electric shock as USC resulted in decreased HR (UCR). This was paired with CS of flashing light. Decrease in HR was classically conditioned when light was exposed to subject
• Van Egeren et al 1972: showed individual differences in classical conditioning of heart activity after exposure of aversive stimuli, thus important to consider individual differences
• Furedy and Puolos 1976: attempted to condition HR decrease using body tilt as an UCS, this paired with tone as CS, HR decrease can be conditioned however magnitude HR deceleration was largely attenuated (30bpm to 4 bpm)

Operant Conditioning

• Also classified as instrumental conditioning
• A type of psychological learning where individual can shape and modify occurrence of behavioural response
• This can be done by reinforcing factors that could reward or punish subject
• Positive reinforcement- occur when particular behaviour rewarded (eg food, money)
• Negative reinforcement occur when behaviour followed by removal of unpleasant stimulus (eg removal of annoying loud nois)
• Positive reinforcement: occur when behaviour is followed by unpleasant stimulus ( eg shock treatment)
• Negative punishment- occur when behaviour is followed by removal of pleasant stimuli (eg. kids toy)

Operant conditioning and heart activity

• Previously thought that operant conditioning of heart activity is impossible and is more amendable through classical conditioning
• Several researchers shown that operant conditioning of HR possible : mainly HR acceleration
• HR acceleration believed to be influenced by decrease in vagal tone