Biology and Behaviour
Psychology · Section 1.3 · 18 study cards
Neurons, synapses and transmitters, the nervous system divisions, brain structure and imaging, hormones and behaviour genetics.
Practice this set → Spaced repetition, card by card. No account needed.
Method
Work from small to large, then back down
This unit has four layers stacked on one another: the single neuron, the chemical synapse, the systems of the nervous body, and the brain's regions. Learn them upwards, because each layer is built from the one below, then practise coming back down, because exam questions usually name a behaviour and ask you to place it at the right layer.
The electrical half and the chemical half
Keep them apart. Within a neuron the signal is electrical: an all-or-none action potential that either fires at full strength or does not fire. Between neurons the signal is chemical: neurotransmitters crossing a gap and binding to receptors. Nearly every drug in this course acts on the chemical half, which is why agonist and antagonist are the two words that unlock most drug items.
Procedure for a brain damage question
- Name the deficit precisely. Is it movement, sensation, language, memory, emotion or arousal?
- Map deficit to region rather than region to deficit. Movement coordination points to the cerebellum, new explicit memory to the hippocampus, fear to the amygdala, language production to Broca's area, language comprehension to Wernicke's area, vital functions to the medulla.
- Check the side. Sensory and motor control is contralateral, so left-side weakness means right-hemisphere damage. Language is almost always left.
- Check what is spared. A question that says the patient understands but cannot speak, or moves but cannot balance, is giving you the discriminating detail deliberately.
Structure or function
For imaging, ask only whether the method shows what the brain looks like or what it is doing. CT and MRI are pictures; EEG, PET and fMRI are activity. Lesion work is the oldest method and the only one that establishes that a region is necessary rather than merely active.
Genes are a range, not a blueprint
Every claim in behaviour genetics is about variation within a group and about interaction with environment. Phrase your answers that way and you will avoid the single most penalised error in this unit.
Definitions and theorems
Worked example
A 62-year-old man is brought to hospital after a stroke. He speaks fluently and at normal speed, but his sentences contain many invented words and convey little meaning, and he cannot follow a simple spoken instruction. His right arm and right leg are weak. An imaging scan is ordered to see whether brain tissue has been destroyed and where. Identify the damaged language area, name the hemisphere, explain the limb weakness, and say which scan is appropriate and why.
Classify the language deficit by fluency. Speech is fluent but empty, and comprehension is impaired. That pattern is Wernicke's aphasia, not Broca's, where speech would be laboured and comprehension largely preserved.
Locate the area. Wernicke's area lies in the temporal lobe, close to the auditory cortex, which fits its role in understanding language.
Name the hemisphere. Language is lateralised to the left hemisphere in the great majority of people, so the damage is left temporal.
Check the limb weakness against that conclusion. Motor control is contralateral, so weakness on the right side of the body indicates left-hemisphere damage. The two findings agree, which confirms the localisation.
Say where the motor damage sits. Weakness of the arm and leg implicates the motor cortex along the rear edge of the frontal lobe, or the pathways descending from it, on the left.
Choose the scan. The question asks whether tissue has been destroyed and where, which is a question about structure, so an MRI (or a CT scan in the acute setting) is appropriate. fMRI and PET show function rather than damage, and EEG would give electrical activity with poor spatial precision.
Common mistakes
- Saying a stronger stimulus makes a bigger action potential. The all-or-none principle forbids it. Intensity is signalled by the rate of firing and by the number of neurons firing. Any answer describing a larger or faster impulse for a stronger stimulus loses the mark.
- Mixing up the sympathetic and parasympathetic divisions. Sympathetic arouses, parasympathetic calms, and neither has anything to do with sympathy. A memory hook that survives exam pressure: parasympathetic is the parachute that brings you back down.
- Reversing Broca's and Wernicke's aphasia. Decide on fluency first. Broken, effortful speech with intact understanding is Broca's, in the frontal lobe; fluent, meaningless speech with poor understanding is Wernicke's, in the temporal lobe.
- Confusing MRI with fMRI, or CT with PET. Sort every imaging item by structure against function before you pick. CT and MRI photograph the brain; EEG, fMRI and PET record what it is doing. The f is functional, and it is the whole difference.
- Reading heritability as how much of my trait is genetic. Heritability describes variation across a group in a given environment. Saying that a heritability of 0.50 means half of one person's intelligence comes from genes is the standard trap, and the corrected wording is the answer the marker is looking for.
Practice it
Reading the method is not the same as being able to recall it under pressure. This set drills 18 cards one at a time and schedules each card separately, so the ones you keep missing come back sooner.