learning Flashcards

(100 cards)

1
Q

What is learning in neuroscience?

A

Learning is a relatively lasting change in behaviour or brain function
• Caused by experience
• Occurs via changes in synaptic strength and neural circuits

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2
Q

What is the biological basis of learning in the brain?

A

• Learning occurs through synaptic plasticity
• Involves strengthening or weakening of connections between neurones
• Alters prediction of outcomes

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3
Q

What is associative learning?

A

• Learning that two events or actions are linked
• Forms associations such as stimulus–stimulus or action–outcome
• Core mechanism underlying conditioning

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4
Q

What is Hebbian learning?

A

Hebbian learning is activity-based learning
• Described as ‘neurones that fire together wire together’
• Repeated co-activation strengthens synapses

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5
Q

How does Hebbian learning work at the synapse?

A

• Repeated firing of presynaptic and postsynaptic neurones together
• Leads to long-term potentiation (LTP)
• Increases synaptic efficiency

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6
Q

Which receptors are central to Hebbian learning?

A

NMDA receptors detect coincident activity
• Allow calcium influx
• Trigger insertion of AMPA receptors

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7
Q

Which brain regions rely heavily on Hebbian learning?

A

Hippocampus – memory formation
Cerebral cortex – perceptual and skill learning

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8
Q

Why is Hebbian learning NOT reward-based?

A

• It depends on neuronal co-activity, not outcomes
• No reward or punishment signal required
• Learning is correlation-based

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9
Q

What is unsupervised learning?

A

• Learning occurs without external feedback
• The system detects patterns and regularities
• No teacher and no error signal

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10
Q

What does the brain do during unsupervised learning?

A

• Groups similar inputs
• Extracts statistical structure
• Organises sensory information

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11
Q

What are examples of unsupervised learning in humans?

A

Face recognition
Sensory development in infancy
• Perceptual organisation

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12
Q

What is the neural basis of unsupervised learning?

A

Hebbian plasticity
Sensory cortex reorganisation
• Experience-dependent synaptic changes

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13
Q

How is unsupervised learning relevant to psychiatry?

A

Autism – atypical pattern detection
Schizophrenia – abnormal salience assignment

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14
Q

What is supervised learning?

A

• Learning guided by a teacher or error signal
• System is told what is correct or incorrect
• Learning aims to reduce error

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15
Q

What is the key mechanism in supervised learning?

A

Error correction
• Minimising difference between expected and actual outcome

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16
Q

Which brain structures are associated with supervised learning?

A

Cerebellum – motor learning
Cortical feedback loops

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17
Q

Why is supervised learning less central in psychiatry?

A

• Most psychiatric learning abnormalities involve reward and salience
• Reinforcement learning is more relevant clinically

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18
Q

What is reinforcement learning?

A

• Learning driven by rewards and punishments
• Behaviour shaped by outcomes
• Central computational model in psychiatry

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19
Q

What question does reinforcement learning answer?

A

‘Was the outcome better or worse than expected?’
• Behaviour is updated accordingly

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20
Q

What is reward prediction error (RPE)?

A

RPE = actual reward – expected reward
• Core signal that drives learning

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21
Q

How does dopamine encode reward prediction error?

A

Better than expected outcome → increased dopamine firing
Worse than expected outcome → reduced dopamine firing

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22
Q

Which brain systems mediate reinforcement learning?

A

Dopamine neurones (VTA, substantia nigra)
Basal ganglia
Prefrontal cortex

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23
Q

Why is dopamine NOT a pleasure signal?

A

• Dopamine codes prediction error
• Signals unexpectedness, not enjoyment
• Pleasure can occur without dopamine

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24
Q

How is reinforcement learning altered in depression?

A

• Reduced reward sensitivity
• Blunted dopamine response
• Impaired reinforcement learning

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25
**How is reinforcement learning altered in addiction?**
• Excessive learning of **drug-related cues** • **Habit learning** dominates goal-directed control • Pathological reinforcement
26
**How is reinforcement learning altered in schizophrenia?**
• **Aberrant salience** • Dopamine mis-signals importance • Faulty updating of beliefs and actions
27
**How is learning altered in obsessive–compulsive disorder?**
• Overactive **habit circuits** • Impaired updating based on outcomes • Behaviour persists despite negative consequences
28
**What is the key difference between Hebbian and reinforcement learning?**
• **Hebbian learning** = activity-based • **Reinforcement learning** = outcome-based • Reward is only involved in reinforcement learning
29
**What is a common exam trap involving dopamine?**
• Dopamine does **not code pleasure** • Dopamine codes **prediction error**
30
**Which buzzword indicates Hebbian learning in exams?**
• **‘Fire together, wire together’**
31
**Which buzzword indicates reinforcement learning in exams?**
• **‘Prediction error’** • **‘Better or worse than expected’**
32
**Which buzzword indicates unsupervised learning in exams?**
• **Pattern extraction** • **Statistical regularities**
33
**What are the five exam-critical take-home points about learning?**
• Learning = **synaptic plasticity** • Hebbian = **activity-based** • Unsupervised = **pattern detection** • Supervised = **error correction** • Reinforcement = **dopamine and prediction error**
34
**What do we mean by learning in neuroscience?**
• **Learning** is a **relatively enduring change** • Occurs in **behaviour**, **knowledge**, or **neural function** • Caused by **experience** • NOT due to **maturation**, **fatigue**, or **temporary states**
35
**Why is learning considered a biological process rather than just psychological?**
• Learning involves **physical changes in the brain** • Includes changes in **synaptic strength** • Alters **neuronal firing patterns** • Reorganises **neural circuits** • Represents **brain plasticity**
36
**What is synaptic plasticity?**
• **Synaptic plasticity** is the ability of a synapse to **increase or decrease its strength** • Occurs in response to **neuronal activity** • It is the **core cellular mechanism** of learning and memory
37
**What does activity-dependent plasticity mean?**
• Synapses change **only when neurones are active** • Repeated activity strengthens connections • Inactive synapses weaken (**‘use it or lose it’**) • Explains learning and skill acquisition
38
**What is associative learning?**
• **Associative learning** is learning that **two events are linked** • One event comes to **predict** another • Forms the basis of **conditioning and habits**
39
**What happens in the brain during associative learning?**
• Neurones representing **Event A** and **Event B** fire together • Repeated co-activation strengthens their synapses • Stable neural representations are formed • Explained by **Hebbian learning**
40
**What is Hebbian learning?**
• **Hebbian learning** is an activity-based learning rule • Described as **‘neurones that fire together wire together’** • Repeated co-activation strengthens synapses • It is **NOT reward-based**
41
**What does Hebbian learning mean physiologically?**
• Repeated **synchronous firing** of pre- and postsynaptic neurones • Leads to **long-lasting increases in synaptic efficiency** • Synapse becomes faster and more reliable • Expressed as **synaptic potentiation**
42
**What is long-term potentiation (LTP)?**
• **LTP** is a **persistent increase in synaptic strength** • Follows repeated or strong synaptic activity • Can last **hours to years** • Input-specific and activity-dependent
43
**Why is LTP important for learning and memory?**
• LTP is the **best-studied biological mechanism** of learning • Explains how experiences produce **lasting neural change** • Strongly linked to memory formation
44
**Where was LTP first discovered and why is this important?**
• First identified in the **hippocampus (CA1 region)** • Hippocampus is critical for **declarative and spatial memory** • Supports link between **LTP and memory**
45
**Which neurotransmitter system is central to Hebbian learning?**
• **Glutamate** is the key neurotransmitter • Acts at **AMPA** and **NMDA receptors** • NMDA receptors are the critical **learning gate**
46
**Why are NMDA receptors crucial for Hebbian learning?**
• NMDA receptors act as **coincidence detectors** • Require **glutamate binding** and **postsynaptic depolarisation** • Ensure synapses strengthen only when neurones fire together
47
**What role does magnesium play at the NMDA receptor?**
• NMDA channel is blocked by **Mg²⁺ at rest** • Postsynaptic depolarisation expels Mg²⁺ • Channel opens and **calcium enters** • Makes NMDA receptors **voltage- and ligand-dependent**
48
**Why is calcium entry essential for learning?**
• **Calcium** is the intracellular learning signal • Activates protein kinases (e.g. **CaMKII**) • Triggers gene transcription • Produces long-term synaptic change
49
**What happens to AMPA receptors during LTP?**
• **More AMPA receptors** are inserted into postsynaptic membrane • Existing AMPA receptors become more conductive • Same glutamate causes larger postsynaptic response • Synapse is **potentiated**
50
**What structural synaptic changes occur with long-term Hebbian learning?**
• **Dendritic spines enlarge** • Synapses stabilise • New synapses may form • Synaptic proteins are synthesised
51
**Which brain regions rely heavily on Hebbian learning?**
• **Hippocampus** – declarative and spatial memory • **Neocortex** – long-term memory and skills • **Sensory cortex** – experience-dependent tuning • **Motor cortex** – motor learning
52
**Why is Hebbian learning considered unsupervised?**
• No **reward** is required • No **punishment** is required • No feedback or teacher signal • Learning depends on **co-activation alone**
53
**What are key exam traps related to Hebbian learning?**
• It is **NOT dopamine-dependent** • It is **NOT reward-based** • It does **NOT require reinforcement** • It is **NMDA-mediated and activity-based**
54
**Give a one-sentence exam-perfect summary of Hebbian learning.**
• **Hebbian learning** is an **activity-dependent, NMDA-mediated strengthening of synapses**, in which **repeated co-activation of neurones produces long-term potentiation and stable associative memory**
55
**What are computational learning models in neuroscience?**
• **Computational learning models** describe the **rules** the brain uses to learn from experience • Explain **how synapses change** • Explain **how predictions are updated** • Help understand **normal learning** and **psychiatric disorders**
56
**How many core types of computational learning models does the brain use?**
• The brain uses **THREE core learning types** • **Unsupervised learning** • **Supervised learning** • **Reinforcement learning** • Each relies on **different brain circuits** and fails in **different psychiatric illnesses**
57
**What is unsupervised learning?**
• **Unsupervised learning** occurs **without reward** • Occurs **without punishment** • Occurs **without feedback or a teacher** • The brain learns by detecting **patterns**
58
**What question does unsupervised learning answer?**
• Unsupervised learning answers: • **‘What things belong together?’** • Helps discover **structure**, **categories**, and **meaning** • No concept of right or wrong
59
**Give simple real-life examples of unsupervised learning.**
• **Face recognition** • **Speech sound learning** in infancy • **Object recognition** • **Perceptual grouping** • Occurs **automatically**, without feedback
60
**What is the biological mechanism behind unsupervised learning?**
• Main mechanism is **Hebbian learning** • Repeated **co-activation** strengthens synapses • Builds stable neural representations • Occurs **without dopamine** and **without reward**
61
**Which brain areas mainly use unsupervised learning?**
• **Sensory cortices** (visual, auditory, somatosensory) • **Association cortices** (temporal and parietal) • These areas extract **patterns from raw input**
62
**Why is unsupervised learning especially important in early development?**
• Infants receive **no explicit teaching** • Learning occurs through **exposure alone** • Drives **language**, **face recognition**, and **social cue detection** • Strongest during **critical periods**
63
**How is unsupervised learning linked to autism?**
• Pattern detection is **atypical** • Focus on **local details**, not global meaning • Leads to **sensory hypersensitivity** • Difficulty interpreting **social signals** • Brain extracts **different patterns** from the same environment
64
**How is unsupervised learning linked to schizophrenia?**
• Pattern extraction becomes **noisy** • Unrelated events are grouped together • Causes **false associations** • Leads to **ideas of reference** and **delusions** • Known as **aberrant salience**
65
**What is a key exam trap about unsupervised learning?**
• It is **NOT random learning** • It is **NOT reward-based** • It is **statistical pattern learning**
66
**What is supervised learning?**
• **Supervised learning** involves an **explicit error signal** • A ‘teacher’ indicates **right or wrong** • Learning occurs by **correcting mistakes**
67
**What question does supervised learning answer?**
• Supervised learning answers: • **‘How can I improve performance toward a known goal?’** • Focuses on **accuracy** and **fine adjustment**
68
**What is the key biological feature of supervised learning?**
• **Error correction** • Difference between **expected** and **actual outcome** • Synapses change to **reduce future errors**
69
**Which brain structure is most important for supervised learning?**
• The **cerebellum** • Compares intended with actual movement • Uses error signals to fine-tune output • Damage causes **poor motor learning** and **ataxia**
70
**Why is supervised learning less important in psychiatry?**
• Psychiatric symptoms involve **motivation**, **meaning**, and **salience** • These rely more on **reinforcement learning** • Error correction plays a smaller role
71
**What is reinforcement learning?**
• **Reinforcement learning** is driven by **rewards and punishments** • Outcomes are evaluated as **better or worse than expected** • The brain asks **‘Was that outcome worth it?’**
72
**What is reward prediction error (RPE)?**
• **Reward prediction error** is the difference between: • **Expected outcome** • **Actual outcome** • Formula: **Actual − Expected**
73
**How does dopamine relate to reward prediction error?**
• Dopamine firing **increases** if outcome is **better than expected** • Dopamine firing **decreases** if outcome is **worse than expected** • Dopamine codes **learning signals**, NOT pleasure
74
**Which brain circuits are involved in reinforcement learning?**
• **VTA and substantia nigra** (dopamine) • **Basal ganglia** (actions and habits) • **Prefrontal cortex** (decision-making) • **Limbic system** (emotional value)
75
**How is reinforcement learning abnormal in depression?**
• Dopamine responses are **blunted** • Rewards fail to update behaviour • Leads to **anhedonia**, **apathy**, and **low motivation** • Rewards stop ‘teaching’ the brain
76
**How is reinforcement learning abnormal in addiction?**
• Drugs cause **excessive dopamine release** • Rewards are **over-valued** • Drug cues become **pathologically reinforced** • Leads to **craving**, **compulsion**, and **habitual use**
77
**How is reinforcement learning abnormal in schizophrenia?**
• Dopamine signals occur at **inappropriate times** • Neutral events feel **important** • Causes **aberrant salience** • Leads to **delusions and psychosis**
78
**How is reinforcement learning abnormal in OCD?**
• **Habit circuits** dominate behaviour • Outcome updating is impaired • Leads to **repetitive compulsions** • Behaviour persists despite insight
79
**What are the biggest exam traps in computational learning models?**
• **Hebbian ≠ reward** • **Dopamine ≠ pleasure** • **Unsupervised ≠ random** • **Reinforcement ≠ simple reward**
80
**Give a simple mnemonic for learning models.**
• **HUR Learning** • **H**ebbian → **H**appens together • **U**nsupervised → **U**nlabelled patterns • **R**einforcement → **R**eward prediction error
81
**Why are computational learning models important for understanding psychiatric disorders?**
• Many psychiatric symptoms arise from **abnormal learning** • Involve **faulty belief updating** • Involve incorrect assignment of **salience** • Biologically reflect **synaptic plasticity abnormalities** • Involve **dopamine signalling errors** • Occur in **cortico–striatal circuit dysfunction** • Psychiatric illness = **disordered learning**, not just chemical imbalance
82
**What is the shared pathophysiological theme across psychiatric learning disorders?**
• Failure of **pattern formation** (unsupervised learning) • Failure of **error correction** • Failure of **reward prediction error signalling** • Failure to switch between **goal-directed and habitual control** • Deficits occur in **specific neural circuits**, not globally
83
**How does unsupervised learning normally work in the brain?**
• Repeated **co-activation** of sensory neurones • **Hebbian plasticity** strengthens correct associations • Stable **internal models** of the world form • Depends on **NMDA-mediated plasticity** • Requires balanced **excitation and inhibition** • Requires low cortical **noise**
84
**What goes wrong with unsupervised learning in autism?**
• Altered **synaptic plasticity** • **Excitation–inhibition imbalance** (↑ glutamate / ↓ GABA) • Reduced **integration across cortical areas** • Over-learning of **local features** • Under-learning of **global patterns** • Sensory cortex plasticity is **over-detailed but poorly integrated**
85
**How does abnormal unsupervised learning explain autistic symptoms biologically?**
• Sensory inputs encoded **too precisely** • Reduced **noise filtering** • Impaired extraction of **higher-order meaning** • Produces **sensory hypersensitivity** • Causes difficulty with **social pattern recognition** • World feels **overwhelming and fragmented**
86
**What goes wrong with unsupervised learning in schizophrenia?**
• Cortical learning becomes **unstable** • **Random co-activation** is reinforced • Reduced **signal-to-noise ratio** • NMDA receptor **hypofunction** • Cortical **disinhibition** • Excess background **dopamine influence**
87
**How do unsupervised learning failures lead to delusions and perceptual abnormalities?**
• Unrelated stimuli are **grouped together** • **False associations** are learned • Internal representations lose **boundaries** • Leads to **ideas of reference** • Produces **delusions and perceptual distortions** • Known as **aberrant pattern formation**
88
**How does supervised learning normally work biologically?**
• Relies on explicit **error signals** • Compares **intended vs actual outcomes** • Uses **cerebellar error correction** • Synapses adjust to **reduce future error** • Improves **precision and timing**
89
**What happens when supervised learning systems fail?**
• **Poor error correction** • Inaccurate predictions • **Inflexible or clumsy behaviour** • Seen in **motor coordination problems** • Seen in **speech and timing abnormalities**
90
**Why is supervised learning less central to core psychiatric symptoms?**
• Psychiatric disorders involve **meaning** • Involve **motivation and value** • Involve **belief formation** • These rely on **reinforcement learning** • Depend on **dopamine-based cortico-striatal circuits**
91
**What is the normal biological role of dopamine in reinforcement learning?**
• Dopamine signals **reward prediction error (RPE)** • ↑ firing = outcome **better than expected** • ↓ firing = outcome **worse than expected** • Updates **synaptic weights** • Guides **future decisions** • Shapes **habits and motivation**
92
**What goes wrong with reinforcement learning in depression?**
• Dopamine **RPE signals are blunted** • Positive outcomes fail to **reinforce behaviour** • Negative outcomes are **overweighted** • Reduced **dopaminergic firing** • Reduced **ventral striatal responsiveness** • Excess **top-down inhibitory control**
93
**How do reinforcement learning abnormalities produce depressive symptoms?**
• Rewards no longer feel **informative** • Behaviour stops being **reinforced** • **Motivation collapses** • Leads to **anhedonia** • Leads to **apathy** • Produces **learned helplessness** • Core pathology = **failure of positive learning**
94
**What goes wrong with reinforcement learning in addiction?**
• Drugs cause **massive non-physiological dopamine release** • **RPE signals are exaggerated** • Learning becomes **distorted** • Drug-cue associations are **over-strengthened** • Natural rewards lose **learning value**
95
**How does addiction shift behaviour biologically?**
• Shift from **goal-directed learning** (ventral striatum) • Shift toward **habit-based learning** (dorsal striatum) • Produces **compulsion** • Causes **loss of control** • Behaviour persists **despite harm** • Addiction = **pathological reinforcement learning**
96
**What goes wrong with reinforcement learning in schizophrenia?**
• Dopamine fires at **inappropriate times** • **RPE signals** occur without real rewards • Dysregulated **dopamine synthesis** • Impaired **cortical control** of midbrain dopamine
97
**How do reinforcement learning abnormalities cause psychotic symptoms?**
• Neutral events feel **important** • Meaning is assigned **incorrectly** • Beliefs updated using **false signals** • Leads to **aberrant salience** • Produces **delusions and psychosis** • Learning occurs from **noise instead of signal**
98
**What goes wrong with reinforcement learning in OCD?**
• **Habit learning** dominates behaviour • Outcome evaluation is **impaired** • **Extinction learning** is weak • Overactive **cortico-striato-thalamo-cortical loops** • Reduced **prefrontal inhibition of habits**
99
**How do reinforcement learning abnormalities explain compulsions?**
• Behaviour no longer guided by **outcomes** • **Habits run automatically** • Anxiety relief acts as **negative reinforcement** • Produces **repetitive behaviours** • Behaviour persists **despite insight**
100
**Give a one-sentence pathophysiological summary for psychiatry exams.**
• Psychiatric disorders arise from **disrupted synaptic plasticity and dopamine-mediated learning signals** • Leads to **faulty pattern formation** • Causes **abnormal salience** • Produces **impaired reward learning** • Allows **maladaptive habits to dominate behaviour**