PSYC1011 Chap.4 Psychobiology: Neurons, Systems and Behaviour

Psychobiology: Neurons, Systems and Behaviour

Psychobiology asks how biological processes constrain and enable psychological function, not how to replace psychological explanation with brain vocabulary. A complete account can move among cellular events, neural circuits, behaviour and environment while preserving the question at each level.

Saying that behaviour is in the brain is too broad; saying that one activated area is the behaviour is too narrow.

A neuron's resting potential reflects ion distributions, selective membrane permeability and active transport.

An action potential is an all-or-none regenerative event once threshold is reached; stimulus intensity is represented through firing rate and population activity rather than a taller action potential. Refractory periods influence firing and directional propagation.

These details matter when a psychological claim depends on signal timing or loss of conduction.

At a chemical synapse, an arriving action potential triggers transmitter release, receptor binding changes postsynaptic activity, and clearance limits the signal. Excitatory and inhibitory describe effects on the likelihood of postsynaptic firing in that circuit, not whether a transmitter is universally good or bad.

A drug can alter synthesis, release, receptor action, reuptake or breakdown, and the behavioural effect depends on location, dose and system response.

The nervous system is organised across central and peripheral divisions, sensory and motor pathways, and interacting cortical and subcortical networks.

Autonomic sympathetic and parasympathetic activity support changing bodily demands rather than a simplistic on–off opposition. Endocrine signals operate on different time scales and interact with neural regulation. Functional descriptions should identify pathway, timing and measured outcome.

Localisation evidence has several strengths and limits.

A lesion can support necessity if damage is sufficiently specific and alternative deficits are excluded. Stimulation can provide intervention evidence but may spread. Neuroimaging measures a correlate of neural activity with spatial and temporal constraints; reverse inference from activation to one mental process is risky because regions participate in many tasks.

Converging methods produce a stronger claim than one vivid image.

Plasticity means experience and injury can change neural function, yet it does not imply unlimited recovery. Compensation may recruit different strategies or systems and can improve behaviour without restoring the original mechanism. Developmental timing, practice and remaining tissue matter.

A before–after scan needs behavioural measures and a comparison before a training programme can be called the cause of neural change.

Worked lesion interpretation: a patient with medial temporal damage shows poor new episodic learning but retains working-memory performance over short delays and previously acquired skills.

The pattern supports a critical contribution to forming certain long-term memories; it does not show that all memory is stored in one site. Task demands, lesion extent and preserved abilities define the inference.

In exam reasoning, start with the psychological contrast, name the biological level, identify the method and state what the observation establishes. Then add a converging result or limitation.

This prevents a list of structures from masquerading as explanation and keeps correlation, intervention, necessity and sufficiency distinct.

When comparing biological explanations, distinguish necessary, sufficient and modulatory contributions. A structure can be necessary for one task without being sufficient to generate the whole process, and a transmitter can change probability without determining one behaviour.

Dose, baseline state and network feedback can reverse or flatten an effect. Strong answers use interacting systems and specify the psychological outcome, while weak answers attach one everyday feeling to one chemical as if the mapping were fixed.

Conclude with the method-specific verb and the behavioural contrast so biological detail remains connected to the psychological question.

What this chapter covers

• 01

  action potential

• 02

  synaptic transmission

• 03

  localisation

• 04

  connect neural signalling and brain systems to behaviour without collapsing levels of explanation

• 05

  Brain activation associated with a task is not sufficient evidence that the activated region uniquely causes the psychological process.

Interpret converging brain evidence

Key terms

action potential

A regenerative electrical event that carries a signal along an axon.

synaptic transmission

Communication in which a presynaptic cell changes signalling in a postsynaptic cell.

localisation

The claim that a function depends especially on particular neural structures or networks.

Psychobiology: Neurons, Systems and Behaviour FAQ

Exam move

Build a construct–operation–comparison–inference map, then change one cue, contingency, measure or design feature and predict the revised result.

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