What is "The Knowledge" and why does it have such value for testing a hypothesis about neuron growth and cognitive training? Compare and contrast cross-sectional and longitudinal studies, describing the strengths and weaknesses of each for testing the hypothesis of this study's researchers.

"The Knowledge" is mastering the layout of more than 25,000 streets within a six-mile radius of the central train station, which is necessary to become a cab driver in London. "The Knowledge" creates new neurons due to the increased demand placed on the posterior hippocampus as cabbies navigate the streets. It is important for testing a hypothesis about neuron growth and cognitive training because it can show neuron growth and highlights how it greatly influences the size of the posterior hippocampus. A cross-sectional study compares cab drivers with non-cab drivers. While a longitudinal study looks at cab drivers who have not yet learned "The Knowledge." The longitudinal study also involves checking the size of their posterior hippocampus while they are learning and after they have learned "The Knowledge." The cross-sectional study is less accurate and involves more uncertainty than the longitudinal study, but it is faster, cheaper, and easier to complete. It also does not consider time as a factor and only shows data from one point in time. While the longitudinal study is much more difficult to carry out, it is more accurate because it includes several key measurements with a more specific participant population. They also consider a longer period of time than the cross-sectional study.

Differentiate between proximate and ultimate causation. Give an example of each.

Proximate causation refers to the "how" in how something happens. It is the physiological mechanism by which something occurs. An example might be the physiological mechanisms of birds migrating or the flight or fight response.
Ultimate causation refers to the "why" of an event. It is the evolutionary explanation that we can give for something. An example might be why is it that natural selection has selected those birds that do migrate or those individuals who have effective fight or flight responses.

1. What is the "take-home message" of this graph?
2. What does the asterisk above the two bars for "Qualified trainees" signify? Does the lack of an asterisk above the other two pairs of bars have any significance?
3. Before this study, an alternative explanation for cab drivers having a large posterior hippocampus was proposed. What was that hypothesis? What evidence is supplied by this graph relevant to that hypothesis?
4. Each participant in the study was measured at two points in time. What differed between the two time periods?
5. What can you learn from later measurements of the same cab drivers that you could not determine from a comparison of cab drivers versus noncab drivers?
6. The y-axis is labeled "Gray matter intensity." Why do you think that measure is used rather than "number of brain cells"?
7. The blue-green bars (Time 1) for each of the three groups are all the same height. What does this tell us?

1. The "take home" message of this graph is that based on the longitudinal study, we can see that acquiring "The Knowledge" is associated with an increase in the size of the posterior hippocampus and with better performance on memory assessments.
2. The asterisk above the two bars for "Qualified trainees" means that there is a statistically significant difference between the size of the participant's hippocampus from Time 1 to Time 2. The lack of an asterisk above the other two bars means that there is no statistically significant difference between the size of the participant's hippocampus between Time 1 and Time 2.
3. The hypothesis was that people differ innately in posterior hippocampus size, and those with a larger hippocampus are simply predisposed to be successful cab drivers. The data on the graph showed that there were no differences between the 3 groups at T1 but only differences between T1 and T2, which shows that the training and learning "The Knowledge" was responsible for the increase in hippocampus size.
4. Time 1 represents when the participants did not know "The Knowledge," and Time 2 represents when participants learned "The Knowledge."
5. From the longitudinal study, we can learn that acquiring "The Knowledge" increases the size of the posterior hippocampus, whereas, from the cross-sectional study, we can only see those cab drivers already have an increased posterior hippocampus compared to non-cab drivers.
6. It is labeled "Gray matter intensity" instead of "number of brain cells" because it is extremely difficult to count the individual number of brain cells that someone has.
7. It tells us that all the participants across all three groups started out with the same size posterior hippocampus, and there was no statistically significant difference between the beginning sizes of all participants. This means that any differences between Time 1 and Time 2 can be attributed to acquiring "The Knowledge."

The brain uses more energy than any other human organ. Moreover, about two-thirds of the energy used by the brain is to fuel action potentials. What is an action potential? Moreover, which part of the process of generating action potentials accounts for most of the energy used? In your answer, include a graph indicating the electrical changes that occur during an action potential and describe what is responsible for these changes.

The action potential is the rapid change in voltage across a cell membrane. It is a critical process for effectively relaying information and messages to other neurons and cells by propagation. The action potential threshold is reached when the neuron's depolarization is enough to trigger an action potential (when it reaches peak amplitude) through an explosive change in the membrane potential that brings it closer to zero. As the action potential moves along the axon and reaches an "output zone," or the axon terminal, the neuron transfers its information and signal to other cells. (The action potential is a rapid change in voltage across a cell membrane. It is an electrical signal that travels along an axon from neuron to neuron, activated when the sum of total signals coming in is sufficiently positive.)
Sodium and potassium ion channels use the most energy during this process because this helps neurons fire.

why are the senses of taste and smell closely connected in humans

the air in the mouth throat, and nasal passages circulates around all these areas