Psychophysiology: Definition and Aims

• Course Review: Psychophysiology

Psychophysiology: Definition and Aims

• Psychophysiology studies the interrelationships between mind and body.
• It focuses on the connection between physiology and human behavior.
• Neuro-team disciplines, such as neurophysiology, neuroendocrinology, neurochemistry, and neuroscience, as well as Psycho-team fields like psychology and psychobiology, are related to psychophysiology.
• Neuropsychology is also an offspring of the discipline.
• Aims to establish the neurobiological mechanisms that trigger physiological responses.
• Aims to identify the physiological system involved in problematic behavior and its subsystems, such as SNN or PNN.
• Psychophysiology has been proven useful in healthcare applications.
• Psychophysiology has been applied to medical conditions like chronic pain, asthma, dermatitis, and hypertension.

Autonomic Nervous System

• Includes the sympathetic, parasympathetic, and enteric nervous systems.
• Both the sympathetic and parasympathetic divisions involve ganglia.
• Preganglionic cells originate in the central nervous system.
• Preganglionic cells are cholinergic in both divisions.
• The sympathetic division originates in the thoracic and lumbar regions.
• The parasympathetic division originates in the cranial and sacral regions.
• Postganglionic cells are noradrenergic in the sympathetic division.
• Postganglionic cells are cholinergic in the parasympathetic division.
• Effector's membrane receptor is a- and β-adrenergic in the sympathetic division.
• Effector's membrane receptor is muscarinic acetylcholine in the parasympathetic division.
• The sympathetic division is associated with the "fight or flight" or acute stress response.
• The parasympathetic division facilitates the "rest and digest" response.
• The Enteric Nervous System (ENS) is referred to as the "second brain" because of its complexity and functional independence from the CNS.
• The ENS, located within the walls of the gastrointestinal tract, regulates digestive processes like motility, secretion, and blood flow.
• The ENS communicates with the central nervous system via the autonomic nervous system, but can also function autonomously.
• ENS detects mechanical and chemical stimuli within the gastrointestinal tract, providing feedback on digestion and harmful substances.
• ENS communicates bidirectionally with the central nervous system, influencing emotions, mood, and stress responses, known as the Gut-Brain-Axis.

Hypothalamic-Pituitary-Adrenal (HPA) Axis

• HPA is a crucial neuroendocrine system responsible for the body's stress response and regulation of various physiological processes.
• Involves the coordination of the hypothalamus, pituitary gland, and adrenal glands.
• The HPA axis is activated in response to stressors detected by the brain's limbic system and other sensory inputs.
• The hypothalamus releases corticotropin-releasing hormone (CRH) in response to stress, which stimulates the pituitary gland at the anterior lobe, via the hypophyseal portal system.
• CRH prompts the pituitary gland to release adrenocorticotropic hormone (ACTH) into the bloodstream.
• Adrenocorticotropic hormone (ACTH) stimulates the adrenal glands to release cortisol, the primary stress hormone, into the bloodstream.
• Cortisol regulates metabolism, immune function, blood pressure, and glucose levels to prepare the body for the "fight or flight" response.
• Elevated cortisol levels inhibit further release of CRH and ACTH via negative feedback, restoring balance.
• Oxytocin reduces the sympathetic nervous branch activation of ANS, the HPA axis, and increases parasympathetic activity in the brainstem.

Stress, Allostasis, and Homeostasis

• Stress: Physiological response that prepares defense in the face of a stimulating or threatening situation.
• Homeostasis: Tendency of natural state of balance.
• Allostasis: Tendency of the natural state of searching for new balances in shorter periods.
• Allostatic load: Is the accumulated exhaustion of physiological adaptive responses.
• A prolonged response to stress, also known as chronic stress, affects allostatic load.
• Repetitive situation, systematic violence, and drug abuse influences allostatic load
• Sleep deprivation, migration affects allostatic load
• Anxiety and phobias affects allostatic load
• Systems involved: ANS, Immune, Metabolic, Cardiac and HPA systems.
• Cortisol activates amygdala.
• Sustained activation could lead to atrophy in both amygdala and hippocampus.
• Stimulus: Any salient event, whether positive (pleasure) or negative (problems), that triggers a response.
• Response: Output in reaction to a triggering stimulus (e.g., some symptoms).
• Transactional, reactive scope, adaptive calibration, cognitive activation theory of stress (CATS), feedback and feedforward control are all examples of models.

Reactive Scope Model (Romero et al., 2009)

• It's an extension of the concept of allostasis, and is not limited to energy expenditure (wide range of contexts).
• Reactive Scope Model offers predictions about individual differences in stress susceptibility (due to genetic and developmental factors).
• Predictive homeostasis anticipates changes following circadian and seasonal fluctuations.
• Reactive homeostasis features temporary increases in response.
• High levels of mediators induce pathological damage resulting in homeostatic overload.
• Low levels of mediators fail to maintain homeostasis, resulting in homeostatic failure.
• Mediators of stress response: glucocorticoids, heart rate, behavioral responses.

Cognitive Activation Theory of Stress (CATS) (Ursin and Eriksen, 2004, 2010)

• Takes a cognitive perspective on stress.
• Defines stress as a general alarm response to discrepancies between expectancy and reality.
• Non-specific physiological arousal persists until discrepancy dissolves.
• Violations of expectancies can be caused by threats, imbalances, and novelties.
• Cognitive Activation Theory of Stress expectancies are quantified by strength, perceived probability of the expected event, and positive or negative affective connotation (valence) of the event. -Anxiety is related to perceived probability and negative valence of future events. -Helplessness is when coping responses are ineffective. -Hopelessness is when future outcomes are perceived as negative and uncontrollable.

Feedback and Feedforward Control

• Feedback (closed-loop) and feedforward (open-loop) are primary control strategies.
• Feedback is adjustments based on current system output.
• Feedforward is actions based on predicted future states.
• Feedback compares a set point (goal) with the actual state to generate an error signal.
• The error signal drives corrective actions (e.g., thermostat activating heater).
• Feedback measures system output and adjusts continuously to close the loop.
• Feedforward is an open-loop control actions not adjusted based on output.
• Feedforward relies on predictions and models of system behavior.
• Feedforward is effective in stable environments with predictable disturbances.
• Transactional Model (Lazarus & Folkman, 1984) aims to understanding daily stress and coping mechanisms.
• Stress arises from subjective appraisals of situations involving continuous evaluation of the situation and coping resources
• Coping is constantly changing cognitive and behavioral efforts to manage demands perceived as.
• Motivated behavior can be triggered when disturbances move variables from the set point.
• Biological motivations, stimulus oriented, and learnt are motivational states that are part of homeostasis.

Biological Rhythms

• Biological Rhythms are cyclical changes in physiological and behavioral processes driven by internal biological clocks and influenced by external factors.
• Cycle completes in aprox 24 hours = circadian
• Cycle completes in <24 hours = ultradian
• Cycle completes >24 hours = infradian
• Suprachiasmatic Nucleus (SCN) is the "master clock" allowing to adjust internal and external timing
• This adjustment is called entrainment
• Zeitgebers are all cues (sunlight, temperature and social) that help to reg internal clocks The genes involved: CLOCK, BMAL1, PER, and CRY interact in a complex feedback loop.
• There are expression levels oscillating over a 24-hour period .
• It may regulate the timing of biological processes

Physiological Variables & Its Values

• Variable: Breathing rate

• Unit of Measurement: Breaths per minute (BPM)

  • Parasympathetic Response: 6-8 BPM
  • Resting Rate: 8-15 BPM
  • Sympathetic Response: 15-22 BPM

• Variable: Skin Conductance

  • Unit of Measurement: µSiemens (µS)
  • Parasympathetic Response: 0.2-4.9 µS
  • Resting Rate: 5-9 µS
  • Sympathetic Response: >9 µS

• Variable: Heart Rate

  • Unit of Measurement: Beats per minute (LPM)
  • Parasympathetic Response: <60LPM
  • Resting Rate: 60-100LPM
  • Sympathetic Response: >100LPM

• Variable: Heart Rate Variability

  • Unit of Measurement: Hertz (Hz)
  • Parasympathetic Response: 0.15-0.4Hz
  • Resting Rate: 0.04-0.15Hz
  • Sympathetic Response: 0.0033-0.04

• Variable: Peripheral Temperature

  • Unit of Measurement: Celsius (°C) or Fahrenheit (°F) degrees
  • Parasympathetic Response: 32.2-35°C
  • Resting Rate: 23.8-31.6°C
  • Sympathetic Response: <23.8°C

• Note: Proper cleaning of the body area and proper placement of sensors is a must!*