Is it true that Stress is always negative and harmful.?

Acute stress, particularly the fight-flight-freeze response, is adaptive and prepares the body to respond rapidly to threats. Chronic stress, however, is detrimental.

Is it true that Memory is like a video recording, perfectly stored and retrieved.?

Memory is a reconstructive process; retrieval involves combining stored information with other available data, which can lead to inaccuracies or distortions.

Is it true that Once learned, skills and memories are fixed.?

Synaptic plasticity allows for the strengthening (LTP) and weakening (LTD) of neural connections, meaning learning and memory are dynamic and can change over time.

Nervous System, Stress, Learning, Memory, and Sleep Cheat Sheet

Understanding the nervous system's structure, neurotransmitters, and plasticity is key to comprehending how experiences shape behavior and memory. Stress impacts this system through biological and psychological pathways, while learning and memory involve distinct processes and brain regions. Sleep is a vital, complex biological rhythm essential for mental wellbeing.

Core Principles

Nervous System Organization: The CNS (brain, spinal cord) processes information, while the PNS (nerves) transmits it. The Somatic NS handles conscious responses, and the Autonomic NS regulates unconscious functions (Sympathetic for arousal, Parasympathetic for calm).
Synaptic Transmission: Neurons communicate via neurotransmitters released into the synaptic gap, binding to receptors on the postsynaptic neuron to influence its firing likelihood.
Neurotransmitters & Neuromodulators: Glutamate (excitatory, learning) and GABA (inhibitory, calming) are key neurotransmitters. Dopamine and Serotonin act as both neurotransmitters and neuromodulators, influencing mood, reward, and more.
Synaptic Plasticity (LTP/LTD): The brain's ability to change at synapses (strengthening via LTP, weakening via LTD) is the basis for learning and memory, involving structural changes like sprouting, rerouting, and pruning.
Stress Response (GAS & Transactional Model): Selye's GAS describes biological stages (Alarm, Resistance, Exhaustion). Lazarus & Folkman's model emphasizes psychological appraisal (primary: relevance, secondary: coping resources) as crucial.
Learning Mechanisms: Classical conditioning (involuntary association), Operant conditioning (voluntary behavior + consequences), and Observational learning (attention, retention, reproduction, motivation, reinforcement) are core learning types.
Memory Systems: Memory involves Encoding, Storage, and Retrieval. The Atkinson-Shiffrin model outlines Sensory, STM (7±2 items, 12-30s), and LTM (unlimited, permanent). LTM includes explicit (semantic, episodic) and implicit (procedural, emotional) types.
Sleep Architecture: Sleep consists of NREM (N1, N2, N3) and REM stages, each with distinct brainwave patterns (EEG), muscle activity (EMG), and eye movements (EOG).
Circadian & Ultradian Rhythms: Circadian rhythms (~24h, regulated by SCN and melatonin) govern sleep-wake cycles, while ultradian rhythms (~90 min) describe cycles within sleep.
Mental Wellbeing Continuum: Wellbeing exists on a continuum from high functioning to mental disorder, influenced by biological, psychological, social, and cultural factors. Resilience is key to navigating adversity.

Action Steps

1. Strengthen neural pathways for learning by repeatedly activating relevant neural pathways, leveraging Glutamate's excitatory role.
2. Manage stress by identifying personal stressors (internal/external) and employing appropriate coping strategies (approach vs. avoidance) based on context-specific effectiveness.
3. Enhance memory encoding by using mnemonics like the Method of Loci or Acrostics, and ensure sufficient sleep for consolidation.
4. Improve sleep hygiene by maintaining a consistent sleep schedule, optimizing room temperature (19-21°C), and minimizing blue light exposure before bed.
5. Support mental wellbeing by fostering resilience, strengthening social connections, and engaging in culturally relevant practices if applicable.

Key Terms

Synaptic Plasticity: The ability of synapses to strengthen or weaken over time, crucial for learning and memory.
LTP (Long-Term Potentiation): A relatively permanent strengthening of synaptic connections due to repeated activation of a neural pathway.
LTD (Long-Term Depression): A relatively permanent weakening of synaptic connections due to repeated low-level activation.
Stressor: An event that causes stress or is perceived as a threat or challenge to coping ability.
Resilience: The ability to recover from adversity and cope with change and uncertainty.
Circadian Rhythm: A biological rhythm that follows an approximately 24-hour cycle, primarily influencing sleep-wake patterns.
Systematic Desensitisation: A psychological therapy involving gradual exposure to a phobic stimulus while using relaxation techniques.

Pro Tips

Use Glutamate for learning: Repeatedly activate neural pathways associated with new information to strengthen connections via LTP.
Balance Glutamate and GABA: Ensure adequate GABA function to counterbalance excitatory glutamate, preventing excessive arousal and anxiety.
Leverage the Gut-Brain Axis: Recognize that stress can alter gut microbiota, impacting neurotransmitter production and psychological state; manage stress to support gut health.
Understand Sleep Cycles: Recognize that REM sleep increases later in the night, while deep N3 sleep is more prevalent earlier, influencing dream vividness and physical restoration.
Apply the Biopsychosocial Framework to Phobias: Understand that phobias arise from a combination of biological (GABA dysfunction), psychological (conditioning, cognitive biases), and social factors.

Pitfalls to Avoid

Ignoring Chronic Stress: Prolonged stress leads to excessive cortisol, suppressing the immune system and depleting resources, increasing vulnerability to illness.
Ineffective Coping: Using avoidance strategies for chronic stressors without addressing the source can provide short-term relief but perpetuate the problem.
Sleep Deprivation Consequences: Being awake for 17 hours can impair performance equivalent to a BAC of 0.05%, and 24 hours to 0.10%.
Mismanaging Circadian Rhythms: Shift work or irregular light exposure disrupts the SCN's signaling, leading to sleep disorders and reduced wellbeing.
Overlooking Cultural Determinants: Failing to recognize the importance of cultural continuity, self-determination, and connection to Country can negatively impact Indigenous mental wellbeing.

Myth vs Reality

Stress is always negative and harmful.: Acute stress, particularly the fight-flight-freeze response, is adaptive and prepares the body to respond rapidly to threats. Chronic stress, however, is detrimental.
Memory is like a video recording, perfectly stored and retrieved.: Memory is a reconstructive process; retrieval involves combining stored information with other available data, which can lead to inaccuracies or distortions.
Once learned, skills and memories are fixed.: Synaptic plasticity allows for the strengthening (LTP) and weakening (LTD) of neural connections, meaning learning and memory are dynamic and can change over time.

Real World Examples

Feeling the heat from a stove.: This is a conscious response involving the somatic nervous system: stimulus (heat) → sensory receptor → sensory neuron → brain processing → motor neuron → muscle response (move hand away).
Learning to ride a bicycle.: This involves procedural memory (implicit LTM), encoded and consolidated by the basal ganglia and cerebellum, and strengthened through LTP in relevant neural pathways.
Experiencing intense fear when seeing a spider.: This specific phobia can be precipitated by classical conditioning (spider NS + frightening event UCS → fear UCR) and perpetuated by operant conditioning (avoidance → anxiety reduction → negative reinforcement).
A student pulling an all-nighter before an exam.: This partial sleep deprivation leads to cognitive impairments (poorer concentration, decision-making) comparable to a BAC of 0.05% or higher, hindering exam performance.

Statistics

STM Capacity: 7 ± 2 items
STM Duration: 12–30 seconds
Performance Impairment (17 hours awake): Equivalent to BAC 0.05%
Performance Impairment (24 hours awake): Equivalent to BAC 0.10%
Ideal Sleep Room Temperature: 19–21°C

Timeline

Before Conditioning: Neutral Stimulus (NS) elicits no relevant response; Unconditioned Stimulus (UCS) elicits Unconditioned Response (UCR).
During Conditioning: NS is repeatedly paired immediately before the UCS.
After Conditioning: The NS becomes a Conditioned Stimulus (CS) and elicits a Conditioned Response (CR).
Alarm Reaction (GAS Stage 1): Initial shock followed by countershock; fight-flight-freeze response activated.
Resistance (GAS Stage 2): Body maximizes resources to cope with a continuing stressor; cortisol levels remain high.
Exhaustion (GAS Stage 3): Energy reserves are depleted; prolonged high cortisol impairs the immune system, leading to vulnerability to illness.

People

Hans Selye: Developed the General Adaptation Syndrome (GAS) model of stress.
Lazarus & Folkman: Developed the Transactional Model of stress, emphasizing psychological appraisal.
Atkinson & Shiffrin: Proposed the Multi-Store Model of memory (Sensory, STM, LTM).

Quiz

Which neurotransmitter is primarily inhibitory and helps balance excitatory activity?: GABA
According to the Atkinson-Shiffrin model, what is the capacity of Short-Term Memory?: 7 ± 2 items
Which stage of sleep is characterized by brain activity resembling wakefulness and vivid dreaming?: REM Sleep