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
• Dpermanently destroys the postsynaptic receptors

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
• Cconnect the brain to the spinal cord
• Dproduce 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 of language function
• Cthe role of the adrenal medulla in stress
• Dthe existence of an endogenous circadian pacemaker

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.