Neural Signalling, Receptors & Memory – Revision Flashcards

These flashcards cover key concepts from electrical and chemical signalling in neurons through to mechanisms of memory, including action potentials, receptor types, neurotransmitters, memory systems, brain regions, and factors affecting remembering and forgetting.

What does Ohm’s Law state in the context of electrical signalling?

Current (I) equals voltage (V) divided by resistance (R): I = V/R.

What is the typical range of the resting membrane potential (RMP) in neurons?

Approximately –60 mV to –90 mV.

If the membrane potential becomes less negative than the RMP, what is this change called?

Depolarisation.

If the membrane potential becomes more negative than the RMP, what is the change called?

Hyperpolarisation.

In biological systems, what particles carry electric charge?

Ions.

Why is the inside of a resting neuron more negative than the outside?

Because the membrane is more permeable to K⁺ leaving the cell than to Na⁺ entering, creating a charge separation.

What is the definition of ‘equilibrium potential’ for an ion?

The membrane voltage at which the ion’s electrical and concentration gradients are equal and opposite, producing no net flux.

Which active transport mechanism maintains the RMP by exchanging ions?

The sodium-potassium (Na⁺/K⁺) pump.

What happens to a neuron if the Na⁺/K⁺ pump is inhibited?

Na⁺ accumulates inside, K⁺ leaks out, the RMP collapses, and neuronal signalling (and potentially life-sustaining functions) stop.

Why is loss of the mitochondrial membrane potential lethal for a cell?

Because it halts ATP production, marking the cell for death.

What is an action potential (AP)?

A rapid, transient reversal of membrane potential from about –70 mV to +30–40 mV and back, used to regenerate current along the neuron.

Why must action potentials be regenerated along the axon?

Because neuronal membranes are leaky; regenerating the AP re-charges the signal so it can travel farther.

List two ways neurons increase conduction velocity.

(1) Increase axon diameter; (2) Insulate with myelin sheath.

Which glial-derived structure provides electrical insulation to axons?

The myelin sheath.

Why do myelinated axons conduct faster than unmyelinated ones?

Myelin reduces ion leakage, so fewer APs are needed (saltatory conduction), speeding information flow.

Give two reasons neurons use chemical signalling at synapses instead of purely electrical signalling.

(1) A physical gap often separates cells; (2) Chemical signals allow integration of multiple inputs so the target can ‘decide’ whether to respond.

Define ‘synaptic signalling’.

Chemical signalling across a specialised junction (synapse) between a neuron and a target cell.

Define ‘non-synaptic signalling’.

Chemical signalling where the neuron releases chemicals that act on nearby cells without specialised synaptic structure.

What are the two broad classes of chemical messengers based on solubility?

Water-soluble and lipid-soluble chemicals.

Where are receptors for water-soluble messengers located and why?

In the cell membrane, facing the extracellular space, because the messengers cannot cross the lipid bilayer.

Where are receptors for lipid-soluble messengers typically found?

Inside the cell (cytoplasm or nucleus) because the messengers diffuse through the membrane.

What is a ‘ligand’ in receptor biology?

The normal chemical signal that binds to a receptor’s binding site and elicits a response.

How do antagonists exert their effects at receptors?

They bind to the receptor without activating it, blocking the natural ligand from binding.

What is the simplest receptor-ligand interaction (Receptor Type 1) described in the notes?

Ligand binding directly opens an ion channel, altering ion flow and the target cell’s membrane potential.

What are regulatory sites on a receptor?

Additional binding regions that modulate how effectively the main ligand can bind or signal.

Which neurotransmitter binds NMDA-type glutamate receptors important for learning and memory?

Glutamate.

What is the function of GABA in the nervous system?

It is an inhibitory neurotransmitter that reduces the likelihood of target cell firing.

How do benzodiazepines (BZDs) influence GABA-A receptors?

They bind regulatory sites, causing the channel to open wider when GABA is present, enhancing inhibition.

State two major similarities between epinephrine and norepinephrine.

Both act as hormones and neurotransmitters and are key to the fight-or-flight response.

Give one key difference between epinephrine and norepinephrine release sites.

Most epinephrine is released from the adrenal medulla, whereas most norepinephrine is released from sympathetic neurons near the adrenal glands and widely in the brain.

List the three stages of memory formation.

Sensory memory, working (short-term) memory, and long-term memory.

How long does information typically persist in sensory memory?

1–3 seconds.

What is the usual duration limit for information in working memory?

Up to about 30 seconds.

Name the three slave systems of working memory.

Phonological loop, visuospatial sketchpad, and episodic buffer.

Which component of working memory acts as the control centre?

The central executive.

What is the typical capacity of working memory in items?

About 7 ± 2 items.

Where is the phonological loop predominantly located in the brain?

Left frontal and parietal lobes.

Which hemisphere mainly hosts the visuospatial sketchpad?

The right hemisphere.

Identify the three main long-term memory (LTM) systems.

Procedural (skills), semantic (facts), and episodic (events).

Which brain structures are crucial for procedural (skill) learning?

Basal ganglia and cerebellum.

Which structure is central to emotional learning within procedural memory?

The amygdala.

What medial temporal-lobe structure is essential for forming new declarative memories?

The hippocampus (along with entorhinal and perirhinal cortices).

Are declarative memories stored in the hippocampus?

No; the hippocampus encodes them for consolidation, but storage is distributed across cortical networks.

What cellular process strengthens synapses during long-term potentiation (LTP)?

Repeated coincident activity in pre- and postsynaptic neurons increases synaptic efficiency, often via Ca²⁺-dependent signalling cascades.

Give two biological reasons memory retrieval declines with ageing.

(1) Hippocampal neuron loss (~5 % per decade); (2) Reduced neurotransmitter (e.g., acetylcholine) production.

How do stress-related factors impair memory formation?

Chronic elevation of stress hormones leads to neuron loss and reduced neurogenesis (the process by which new neurons are formed in the brain).

Distinguish retroactive from proactive interference.

Retroactive: new information hampers recall of old; Proactive: old information interferes with learning new content.

What is ‘motivated forgetting’ (repression)?

Active suppression of memories that are psychologically painful.

List three evidence-based methods to improve memory retention.

Elaborative rehearsal, distributed practice, use of mnemonics.

What rule summarises an effective reading strategy for learning (PQ4R)?

Preview, Question, Read, Reflect, Recite, Review.

What is cue-dependent memory failure?

Inability to recall information because internal or external cues present during encoding are absent during retrieval.

Define ‘long-term depression’ (LTD).

An activity-dependent decrease in synaptic strength, important for memory erasure or refinement.

Which ion triggers presynaptic changes leading to short-term memory formation?

Calcium (Ca²⁺).

Why can depression lead to memory problems?

Reduced serotonin lowers attention to new information, hindering encoding and retrieval.

Explain why myelin is more effective than increased diameter alone for speeding conduction.

Myelin allows saltatory conduction with minimal ion leakage, so fewer APs are needed; simply increasing diameter still suffers from leakage.

What is the role of the episodic buffer in working memory?

It integrates information from the phonological loop, visuospatial sketchpad, and long-term memory into a coherent episode.

Why are telephone numbers often 7–8 digits long?

Because working memory comfortably holds about 7 ± 2 items.

What is the primary purpose of regulatory sites on receptors?

To modulate ligand binding efficacy and thus fine-tune cellular responses.