Central nervous system

Question 1

Functions of the frontal lobes

Answer 1

1. Intelligence
   - Frontal lobotomy consequences include decreased ability to solve complex problems, string together sequential tasks to reach a goal and to multitask
2. Control of motor activity
   - Frontal lobe damage as a result of stroke can result in difficulty writing due to weakness in the arm and hand, and foot drop due to lack of muscle activity
3. Speech articulation
   - Broca’s area is associated with the articulation of speech
4. Moral judgement

Question 2

Function of the parietal lobes

Answer 2

Sensory

• Parietal lobe is involved in mediating sensory signals, so if it is not functioning correctly and receiving sensory signals, people ignore anything that is happening on that side

Question 3

Functions of the temporal lobes

Answer 3

1. Hearing
   - Auditory areas are linked to hearing. A symptom of temporal lobe epilepsy (neuronal over activity) is hearing sounds that are not there
2. Memory
   - Temporal lobe allows you to create long-term memories
   - Anterograde amnesia; unable to form new memories
   - Retrograde amnesia; forgetting things that happened in the past/inability to retrieve past memories
3. Language use and comprehension
   - Wernicke’s area is associated with language use and comprehension

Question 4

Function of the occipital lobes

Answer 4

Vision

• The visual areas of the occipital lobe enable the perception of visual stimuli

Question 5

Limbic system

Answer 5

• Ring of interconnected structures under the cerebral cortex; each side is mirror image of the opposite
• Function is to generate emotions and motivational drives (ie. punishment or reward response)
• Stimulation of punishment areas evoke fear in humans and defensive behaviour in other animals
• Stimulation of reward areas evoke feelings of wellbeing in humans and placid behaviour in other animals
• Most potent reward area is the nucleus accumbens in the hypothalamus
• Reward responses are dependent on the release of the neurotransmitter dopamine

Question 6

Hypothalamus

Answer 6

• Feeding patterns:
  Neurones in hunger and satiety centres monitor glucose and amino acid usage to produce sensations of hunger/satiety
• Control of pituitary gland secretion:
  Hypothalamus secretes hormones which control secretion by the pituitary; helps regulate growth, metabolism and water conservation
• Water conservation:
  Osmoreceptors can detect the concentration of body fluids and can stimulate thirst centre to encourage drinking; can also evoke release of ADH to retain water
• Body temp regulation:
  Hypothalamic thermostat monitors body temp; if temp deviates too far from 37ºC , appropriate physiological responses are activated; heat promoting and losing centres control cutaneous blood vessel diameter, sweating, shivering and piloerection
• Sleep and circadian rhythms:
  Controls our natural patterns of waking and sleeping; does this based on information it receives from branches of the optic nerve that carry info about light levels
• Integral part of flight or flight response

Question 7

Amygdala

Answer 7

Control of sexual behaviour
- Erections
- Ejaculation
- Ovulation
- Uterine activity

Question 8

Hippocampus

Answer 8

• Important in the formation of long-term memories
• Its removal results in anterograde amnesia

Question 9

Thalamus

Answer 9

• Mass of tissue under the cerebral hemispheres and above the midbrain
• Almost all pathways from sensory receptors and organs go through the thalamus to get to the cortex
• ‘Gateway to the cerebrum’ or ‘switchboard of the brain’
• Almost every area of the hypothalamus activates its own region of the cortex
• Activation is vital for cortical activity since disruption of signals travelling to the cortex from the brainstem often causes an unremitting coma
• May be important for memory retrieval since damage to some thalamic areas leads to retrograde amnesia

Question 10

Brainstem

Answer 10

• Links spinal cord with higher centres of the brain
• Midbrain:
  Responsible for pupillary responses of the eyes and eyeball orientation
• Pons:
  Important for several unconscious activities; urination, pneumotaxic centre (controls rate and depth of breathing alongside respiratory centre…)
• Medulla oblongata:
  Contains respiratory centre; neurones within it stimulate the respiratory muscles to contract and inspiration to occur
• Medulla + pons:
  Important role in controlling cardiac output (and therefore BP); cardioacceleratory centre increases heart rate, cardioinhibitory centre slows heart rate and vasomotor centre controls blood vessel diameter

Question 11

Spinal cord

Answer 11

• Cylinder of nervous tissue that originates in the brainstem and passes through the vertebral canal
• Divided into 5 regions (cervical, thoracic, lumbar, sacral, coccygeal)
• Carries both ascending and descending signals (ascending signals = sensory, descending signals = motor)
• Mediates reflexes