Lecture 21- Behaviour Language Learning

What is the main role of the prefrontal cortex (PFC)?

It organizes thoughts and actions by supporting executive functions such as planning, working memory, self-control, and decision making.

Define executive function.

A set of higher-order cognitive processes that allow planning, monitoring, inhibition, and flexible execution of goal-directed behaviour.

Why is the PFC one of the last brain areas to mature significant?

It explains why adolescents often have less developed impulse control, planning, and risk assessment.

What are common effects of prefrontal cortex damage?

Poor planning, lack of concentration, emotional changes, social inappropriateness, apathy, impulsivity, and personality changes

What does the case of Phineas Gage demonstrate about PFC function?

That damage can leave basic cognition intact but cause dramatic personality and social behaviour changes.

What was lobotomy and why is it no longer used?

A surgical procedure severing PFC tracts, once used for mental illness. It caused confusion, apathy, and personality change; it is now obsolete.

Which hemisphere is dominant for language in most people?

The left hemisphere (≈90%).

What is Broca’s area responsible for, and what happens if it is damaged?

Speech production and motor planning for speech. Damage causes expressive (non-fluent) aphasia — difficulty producing speech but comprehension intact.

What is Wernicke’s area responsible for, and what happens if it is damaged?

Language comprehension. Damage causes fluent aphasia — speech is fluent but meaningless, and comprehension is impaired.

Define aphasia.

A language impairment due to brain damage affecting production or comprehension.

Define learning.

A change in behaviour or knowledge resulting from experience.

Define memory.

The set of processes by which learned information is encoded, stored, and retrieved.

What are declarative memories and which brain regions are crucial?

Memories of facts and events that can be consciously recalled; hippocampus and amygdala are crucial for formation, long-term storage is in cortical regions.

What are procedural memories and which brain regions are crucial?

Memories of skills and habits (e.g., riding a bike) that don’t require conscious recall; basal ganglia, cerebellum, and sensorimotor cortex are crucial.

What factors enhance consolidation of short-term into long-term memory?

Emotional impact, survival value, repetition, linking to existing memories, and focused attention.

What is the capacity of short-term/working memory?

Typically 5–9 items, lasting seconds to minutes.

Where is short-term memory thought to be stored?

In the prefrontal cortex.

What structural changes support long-term memory storage?

Long-term potentiation, increased AMPA receptor numbers, dendritic spine growth, and protein synthesis.

What is retrograde amnesia?

Loss of memories formed before an incident, often affecting recent but not older long-term memories.

What is anterograde amnesia?

Inability to form new long-term declarative memories, often due to hippocampal or limbic damage.

What memory abilities are usually spared in patients with anterograde amnesia?

Short-term memory and procedural learning.

Define long-term potentiation (LTP).

A long-lasting increase in synaptic strength following repeated or strong stimulation, thought to underlie memory formation.

What receptors are involved in the initiation of LTP?

AMPA and NMDA glutamate receptors.

Step-by-step, how is early-phase LTP induced?

1. High-frequency glutamate release → AMPA activation depolarises cell.
2. NMDA receptors open (Mg²⁺ block removed) → Ca²⁺ influx.
3. Ca²⁺ activates kinases.
4. AMPA receptors phosphorylated and inserted into membrane.
5. Postsynaptic neuron becomes more sensitive to glutamate.

Why is early-phase LTP not dependent on protein synthesis?

It only requires receptor modification and trafficking, not new gene expression.

What happens during late-phase LTP?

Kinase activation triggers gene transcription and protein synthesis, leading to new AMPA receptors, increased spine volume, and stable structural synaptic changes.

What is the opposite process to LTP?

Long-term depression (LTD), the activity-dependent weakening of synapses.

What role does the hippocampus play in memory consolidation?

It binds elements of new experiences and is essential for early consolidation.

How does systems consolidation progress over time?

Initially hippocampus-dependent, then gradually transferred to cortical networks for long-term storage.

What is synaptic tagging and capture?

A process where synapses activated during early LTP are “tagged” and later capture new proteins to stabilize memory.

What did Phineas Gage’s accident reveal about brain function?

That the prefrontal cortex is crucial for personality, emotion, and social behaviour regulation.

Why is H.M. a famous case study in memory research?

Removal of hippocampus/amygdala left him unable to form new long-term declarative memories but with intact short-term and procedural memory.

How did historical lobotomy procedures inform modern neuroscience?

They demonstrated the PFC’s role in emotion and behaviour, though the procedure was harmful and is no longer used.