Question 23M.3.HL.TZ2.4
| Date | May 2023 | Marks available | [Maximum mark: 5] | Reference code | 23M.3.HL.TZ2.4 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Comment, Outline, State | Question number | 4 | Adapted from | N/A |
After the age of 30, the number of synapses in the various parts of the human brain remain relatively constant. An electron microscope was used to measure the number of synapses in the auditory cortex and visual cortex of brains after autopsies. The graph shows the mean synaptic density in the auditory cortex and visual cortex below the age of 30.
[Source: Reprinted from Huttenlocher, P.R. and Dabholkar, A.S., 1997. Regional Differences in Synaptogenesis In Human
Cerebral Cortex. The Journal of Comparative Neurology 387, pp. 167–178, with permission from Wiley.]
The capacity to learn certain skills such as reading music and learning foreign languages is greater at an early age. Comment on this statement using the data shown in the graph.
[2]
The statement seems justified as:
- data shows there are more synapses at an early age
OR
synapses decrease with age; - more synapses allow for greater learning/cognitive activity;
- information from the sensory neurons (auditory and visual) used to perform higher order functions (such as learning);
- huge variability at very early age in the number of synapses might mean different children might have differences in learning;
- insufficient information / no standard deviation;
Do not accept “connection” instead of “synapse”.
Candidates were very successful at relating age with synaptic density and learning capacity.
Outline the process that reduces the number of synapses.
[2]
- neural/synaptic pruning;
- (neural/synaptic pruning) involves the loss of neurons/dendrites/synapse:
- synapses that are not used do not persist;
Do not accept “connection” instead of “synapse”.
They could also outline very well that neural pruning reduces the number of synapses.
State one method, other than autopsies, to identify the role of different brain parts.
[1]
animal experiments / lesions / fMRI;
“f” must be written in fMRI.
They could state one method to identify the role of brain parts, mainly fMRI.
