Biopsychology

The human nervous system is first divided into two main parts. Which option correctly names this primary division?

• AThe somatic nervous system and the autonomic nervous system
• BThe sympathetic nervous system and the parasympathetic nervous system
• CThe sensory nervous system and the motor nervous system
• DThe central nervous system and the peripheral nervous system✓

Answer: The nervous system divides first into the central nervous system (brain and spinal cord) and the peripheral nervous system. The peripheral system then subdivides into the somatic and autonomic systems, and the autonomic into the sympathetic and parasympathetic branches.

During synaptic transmission, neurotransmitter is released from the presynaptic neurone into the synaptic cleft. By what process does it cross the cleft to the postsynaptic membrane?

• AActive transport requiring ATP
• BElectrical conduction along the myelin sheath
• CDiffusion across the synaptic cleft✓
• DOsmosis through the postsynaptic receptors

Answer: Neurotransmitter molecules diffuse across the synaptic cleft down a concentration gradient and bind to specific receptors on the postsynaptic membrane. Transmission within a neurone is electrical, but transmission between neurones at the synapse is chemical and relies on diffusion.

A neurotransmitter binding to a postsynaptic receptor can be either excitatory or inhibitory. An inhibitory neurotransmitter such as GABA typically:

• Ahyperpolarises the postsynaptic membrane, making an action potential less likely✓
• Bdepolarises the postsynaptic membrane, making an action potential more likely
• Chas no effect on the postsynaptic potential
• Dtriggers reuptake of the transmitter, back into the presynaptic neurone

Answer: An inhibitory neurotransmitter such as GABA causes hyperpolarisation of the postsynaptic membrane (making the inside more negative), which reduces the likelihood that the postsynaptic neurone will fire. Excitatory neurotransmitters cause depolarisation, increasing the chance of an action potential.

In the endocrine system's role in the fight-or-flight response, which structure releases adrenaline into the bloodstream?

• AThe pituitary gland
• BThe adrenal cortex
• CThe thyroid gland
• DThe adrenal medulla✓

Answer: When the sympathetic branch of the autonomic nervous system is activated, the adrenal medulla secretes adrenaline (and noradrenaline) into the bloodstream, producing the physiological changes of fight-or-flight. The adrenal cortex releases cortisol via the slower HPA axis.

Damage to Broca's area, located in the left frontal lobe, characteristically produces which symptom, supporting the localisation of brain function?

• AFluent but meaningless speech with impaired comprehension
• BTotal loss of vision in the left visual field
• CSlow, laboured, non-fluent speech production✓
• DInability to form any new long-term memories

Answer: Broca's area is associated with speech production. Damage causes Broca's aphasia: speech is slow, effortful and non-fluent, though comprehension is relatively intact. Fluent but meaningless speech with poor comprehension is characteristic of Wernicke's aphasia instead.

Sperry's split-brain research studied patients whose corpus callosum had been severed. The corpus callosum normally functions to:

• Aconnect the two cerebral hemispheres, allowing communication between them✓
• Bregulate the release of hormones from the pituitary gland, the master endocrine gland
• Cconnect the brain stem to the spinal cord
• Dproduce and circulate cerebrospinal fluid

Answer: The corpus callosum is a bundle of nerve fibres connecting the left and right cerebral hemispheres. Cutting it (commissurotomy) in Sperry's patients prevented information from passing between hemispheres, revealing lateralised functions such as language being processed mainly in the left hemisphere.

Following brain damage, axons that are close to but not directly affected by the injury may form new connections to take over lost functions. This aspect of functional recovery is known as:

• Asynaptic pruning
• Baxonal sprouting✓
• Chemispheric lateralisation
• Dlong-term potentiation

Answer: Axonal sprouting is the growth of new nerve endings from undamaged axons to connect with other neurones, helping to compensate for damaged areas during functional recovery. Other mechanisms include recruitment of homologous areas and reformation of blood vessels (neovascularisation).

Which statement most accurately describes how functional magnetic resonance imaging (fMRI) is used to study the brain?

• AIt records the electrical activity of the brain via electrodes on the scalp with very high temporal resolution
• BIt measures the brain's response to a specific stimulus by averaging many EEG trials
• CIt produces only a static structural image and cannot show activity
• DIt detects changes in blood oxygenation and flow to identify which brain areas are active during a task✓

Answer: fMRI detects changes in blood flow and oxygenation (the BOLD signal) in active brain regions, giving good spatial resolution but relatively poor temporal resolution. EEG measures electrical activity with high temporal resolution, and ERPs are derived by averaging EEG responses to a stimulus.

The sleep-wake cycle, which follows an approximately 24-hour pattern governed by the suprachiasmatic nucleus, is an example of which type of biological rhythm?

• AAn ultradian rhythm
• BAn infradian rhythm
• CA circadian rhythm✓
• DAn exogenous rhythm

Answer: A circadian rhythm lasts about 24 hours, and the sleep-wake cycle is the classic example, regulated by the suprachiasmatic nucleus (an endogenous pacemaker) and entrained by light. Ultradian rhythms occur more than once a day (e.g. the stages of sleep), and infradian rhythms last longer than a day (e.g. the menstrual cycle).

Maguire et al.'s (2000) study of London taxi drivers found a larger posterior hippocampus compared with controls. This finding is most often cited as evidence for:

• Abrain plasticity, because experience (navigational learning) can change brain structure✓
• Bhemispheric lateralisation, because language function is processed mainly in the left hemisphere
• Cthe role of the adrenal medulla during acute stress
• Dthe existence of an endogenous pacemaker, the suprachiasmatic nucleus, driving circadian rhythms

Answer: Maguire et al. found that the extensive spatial navigation involved in 'The Knowledge' was associated with more grey matter in the posterior hippocampus, with volume positively correlated with time spent as a taxi driver. This demonstrates plasticity: the brain adapts structurally in response to learning and experience.

What is the role of the sympathetic nervous system?

• APreparing the body for fight or flight✓
• BReturning the body to its resting state
• CControlling voluntary skeletal movement
• DCarrying sensory information to the brain

Answer: Sympathetic activation raises heart rate, dilates pupils and diverts blood to muscles. The parasympathetic branch does the opposite, restoring the body afterwards — the rest and digest response.

What is the sequence of the HPA axis in chronic stress?

• AHypothalamus to pituitary to adrenal medulla, releasing adrenaline
• BHypothalamus to pituitary to adrenal cortex, releasing cortisol✓
• CPituitary to hypothalamus to adrenal cortex, releasing cortisol
• DHypothalamus to adrenal medulla to pituitary, releasing cortisol

Answer: CRH triggers ACTH, which stimulates the adrenal cortex to release cortisol. The faster sympathomedullary pathway releases adrenaline from the adrenal medulla and handles acute stress.

What did Broca's area become associated with?

• ASpeech comprehension, with damage causing fluent nonsense
• BSpeech production, with damage causing halting speech✓
• CVisual processing, with damage causing partial blindness
• DMotor coordination, with damage causing loss of balance

Answer: Broca's area in the left frontal lobe governs producing speech; damage leaves comprehension largely intact but output laboured. Wernicke's area handles comprehension, and damage there produces fluent but meaningless speech.

What is hemispheric lateralisation?

• ABoth hemispheres perform identical functions simultaneously
• BThe brain divides every task equally between two hemispheres
• CFunctions transfer between hemispheres throughout adulthood
• DSome functions are dominated by one hemisphere of the brain✓

Answer: Language is typically left-lateralised and spatial processing right-lateralised. Sperry's split-brain research revealed this by testing patients whose corpus callosum had been cut, though the samples were tiny.

What is an endogenous pacemaker?

• AAn internal body clock such as the suprachiasmatic nucleus✓
• BAn external cue such as daylight that resets the body clock
• CA hormone released in response to changing light levels
• DA rhythm lasting considerably longer than twenty-four hours

Answer: The suprachiasmatic nucleus in the hypothalamus maintains the circadian rhythm even without light cues, though it free-runs slightly longer than 24 hours. External cues are exogenous zeitgebers.

What is an infradian rhythm?

• AA rhythm lasting rather less than twenty-four hours
• BA rhythm lasting longer than twenty-four hours✓
• CA rhythm lasting almost exactly twenty-four hours
• DA rhythm with no fixed period at all

Answer: The menstrual cycle is the standard example. Ultradian rhythms are shorter than a day, such as the stages of the sleep cycle, and circadian rhythms run to about 24 hours.

What does an fMRI scan measure?

• AElectrical activity produced directly by groups of neurons
• BThe structure of the brain without any functional data
• CThe speed at which signals travel along an individual axon
• DChanges in blood oxygenation linked to neural activity✓

Answer: fMRI detects the haemodynamic response, giving good spatial resolution but poor temporal resolution because blood flow lags the neural activity by several seconds. EEG has the opposite trade-off.

What is synaptic transmission?

• AElectrical impulses jumping directly between two neurons
• BHormones travelling through the blood to a target organ
• CNeurotransmitters crossing the gap between two neurons✓
• DSodium ions moving along the length of a single axon

Answer: The impulse triggers vesicles to release neurotransmitter, which diffuses across the cleft and binds receptors on the postsynaptic membrane. Because release is presynaptic only, transmission is one-way.

What is the difference between excitatory and inhibitory neurotransmitters?

• AInhibitory make firing more likely, excitatory make it less likely
• BExcitatory make firing more likely, inhibitory make it less likely✓
• CExcitatory act on the brain and inhibitory act on the spinal cord
• DExcitatory are chemical and inhibitory are purely electrical

Answer: Excitatory transmitters such as glutamate depolarise the postsynaptic neurone; inhibitory ones such as GABA hyperpolarise it. Summation of both determines whether the threshold is reached.

During a night in a sleep laboratory, a participant's EEG shows her passing from light sleep into deep slow-wave sleep and then into REM sleep, a sequence that repeats roughly every 90 minutes.

Which type of biological rhythm is the repeating sleep-stage sequence?

• AAn ultradian rhythm, as it repeats more than once in 24 hours✓
• BA circadian rhythm, as it repeats about once in 24 hours
• CAn infradian rhythm, as it repeats more than once in 24 hours
• DAn infradian rhythm, as each cycle lasts longer than 24 hours

Answer: A cycle of about 90 minutes repeats several times within a day, which makes it an ultradian rhythm. Circadian rhythms, such as the sleep-wake cycle, last about 24 hours, and infradian rhythms, such as the menstrual cycle, last longer than 24 hours.

At the age of six, Jamie had surgery that removed much of the left hemisphere of his brain. His language was badly affected at first, but within two years it had largely recovered.

Which explanation best accounts for Jamie's recovery?

• ALateralisation, as language is usually controlled equally by both hemispheres
• BFunctional recovery, as areas in the right hemisphere took over language✓
• CLocalisation, as Broca's area regrew in the left hemisphere after surgery
• DSynaptic pruning, as unused right-hemisphere connections were removed

Answer: With much of the left hemisphere gone, the recovered language must be supported by other areas, chiefly in the right hemisphere: functional recovery through plasticity, which is greater in young children. Language is normally lateralised to the LEFT hemisphere rather than shared equally, removed tissue does not regrow, and pruning removes connections rather than building the new ones needed to take over a function.

Walking home at night, Zara hears footsteps running up behind her. Within seconds her heart is pounding and her mouth feels dry.

Which sequence best explains these immediate changes?

• AThe hypothalamus activates the sympathetic nervous system, and the adrenal medulla releases adrenaline✓
• BThe hypothalamus activates the parasympathetic nervous system, and the adrenal cortex releases cortisol
• CThe pituitary releases ACTH, and the adrenal cortex releases adrenaline into the bloodstream
• DThe hypothalamus releases CRH, and the thyroid gland releases cortisol into the bloodstream

Answer: An acute threat triggers the sympathomedullary pathway within seconds: the hypothalamus activates the sympathetic branch of the ANS, which stimulates the adrenal medulla to release adrenaline, raising heart rate and reducing saliva. The parasympathetic system calms the body, ACTH and cortisol belong to the slower HPA axis (and cortisol comes from the adrenal cortex, not the thyroid), and adrenaline comes from the adrenal medulla.

A researcher wants to record how brain activity changes from moment to moment as participants move through the stages of sleep across a whole night, with the timing of changes measured to the millisecond.

Which method is most suitable?

• AfMRI, as it records blood flow changes with excellent temporal resolution
• BPost-mortem examination, as it locates brain damage linked to sleep stages
• CERPs, as they record one brain region's response to a single dose of a drug
• DEEG, as it records electrical activity with excellent temporal resolution✓

Answer: EEG uses scalp electrodes to record the brain's overall electrical activity millisecond by millisecond, and its wave patterns distinguish the sleep stages. fMRI has good spatial but poor temporal resolution because blood flow changes lag behind neural activity by a few seconds; post-mortems cannot record a living brain; and ERPs are averaged EEG responses to a specific stimulus, not a whole-night record.

Which of the following is the most valid criticism of Sperry's split-brain research?

• AIt used fMRI scans of healthy volunteers, so it showed correlations rather than effects of cutting the brain
• BIt studied a small number of patients with severe epilepsy, so results may not generalise to typical brains✓
• CIt found that language was controlled equally by both hemispheres, which later lateralisation work contradicts
• DIts patients had had a whole hemisphere removed, so the findings cannot apply to a cut corpus callosum

Answer: Sperry's participants were a small group whose corpus callosum had been cut to control severe epilepsy, and their brains may have developed atypically, so generalising to people with typical brains is questionable. The research tested split-brain patients rather than scanning healthy volunteers, it found language was LATERALISED to the left hemisphere, and the patients' hemispheres were intact but disconnected.