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Flashcards in BLOA - explain effects of neurotransmission Deck (21):

functions of neurons

- send electrochemical messages to the brain
- so people can respond to stimuli either from the environment or from changes in the body



- natural chemical messengers that transmit info between two neighbouring neurons via synapses
- they have specific and highly localized, short-lived effects
- different chemicals can affect behaviour by imitating, increasing the secretion of, or blocking natural neurotransmitters


effects of neurotransmitters

- each neurotransmitter has a different effect on human behaviour
- serotonin is purported to improve mood and serotonin-facilitating drugs (e.g. Prozac) are used to treat depression
- acetylcholine stimulates muscle movement and is believed to play a role in learning memory formation

Serotonin studies:
- Kasamatsu and Hirai (1999)
- Marazziti (1999)

Acetylcholine study: Martinez and Kesner (1991)


process of neurotransmission

method by which messages are sent
- when nerve impulse reaches end of the neuron, the neuron fires neurotransmitters that are released into the synaptic gap
- they bind to receptors on the post-synaptic neuron
- un-absorbed neurotransmitters are re-uptaken, diffused, or destroyed
- if a neurotransmitter is blocked or replaced due to the interference of another chemical, then the messages alter
- this affects the physiological system, cognition, mood, or behaviour


Kasamatsu and Hirai (1999) - Aim

to investigate how sensory deprivation affects the brain


Kasamatsu and Hirai (1999) - Process

- studied a group of Buddhist monks on a 72 hour pilgrimage to a holy mountain in Japan
- the monks did not speak, eat, drink, nor protect themselves in the cold conditions
- after 48 hours, they began to hallucinate ancient ancestors or feel presences
- researchers took blood samples of the monks before ascension and right after the monks reported hallucinations


Kasamatsu and Hirai (1999) - Findings

serotonin levels increased in the monks' brains


Kasamatsu and Hirai (1999) - Conclusion

- sensory deprivation causes the release of serotonin
- the higher levels of serotonin activated the hypothalamus and frontal cortex, resulting in hallucinations


Kasamatsu and Hirai (1999) - Evaluation

- gender imbalance: as only men were used, caution should be used when generalizing to women
- very culturally specific (Japanese monks)


Marazziti (1999) - Aim

To investigate the effect of serotonin on attraction and OCD


Marazziti (1999) - Process

Blood samples were taken from 3 groups:
- attraction: 20 participants who had recently fallen in love and obsessed about it for at least 4 hours per day
- control


Marazziti (1999) - Findings

from analysis of blood samples, serotonin levels of new lovers were equivalent to OCD patients


Marazziti (1999) - Conclusion

the act of falling in love biologically resembles OCD (low levels of serotonin)


Marazziti (1999) - Evaluation

- as this is a correlational study, one shouldn't assume low levels of serotonin caused feelings of attraction or OCD
- in fact, low levels of serotonin may be a consequence rather than a cause
- may be culturally specific to Italy


Martinez and Kesner (1991) - Aim

investigate the role of acetylcholine on memory


Martinez and Kesner (1991) - Procedure

1. rats were trained to go through a maze and get to the end, where they received food
2. after the rats learned this, they were split into 3 groups:
- acetylcholine inhibited: injected with acetylcholine inhibitor
- acetylcholine facilitator: injected with drug preventing serotonin reuptake
- control: no injection
3. memory was measured by seeing how fast the rats could finish the maze


Martinez and Kesner (1991) - Results

- rats with lower acetylcholine were slower
- higher acetylcholine group finished the maze and found the food more quickly, and took fewer wrong turns


Martinez and Kesner (1991) - Conclusion

acetylcholine aids memory (either in its formation or its recall)


Martinez and Kesner (1991) - Evaluation

- animal study: questionable to what extent these findings can be generalized to humans
- biological support: acetylcholine-producing cells are damaged in early stages of AD


transmission process

1. neurotransmitters are stored in vesicles inside the axon
2. vesicles exit the nerve cell via exocytosis, releasing the neurotransmitters into the synaptic gap
3. neurotransmitters bind with a receptor site on the next neuron if the receptor site is the right type of receptor + is vacant (lock-and-key, like enzymes)
4. if enough of the neurotransmitter binds to the receiving neuron’s receptor sites, the neuron will transmit information across its cell body electrically to release neurotransmitters
3. unused neurotransmitters are eventually reabsorbed back into the neuron it came (reuptake) to be reused next time


what to write when asked: "explain the effects of
neurotransmission on human behaviour"

- define neurons and outline their functions
- define neurotransmission and describe its process
- define neurotransmitters and describe their effects
- define serotonin and acetylcholine
- main idea: different neurotransmitters affect different behaviours, and in different ways
- explain WHY those effects occur
- serotonin: Marazzitti (1999) on OCD and love, Kasamatsu and Hirai (1999) on Japanese monks' sensory deprivation causing hallucinations
- acetylcholine: Martinez and Kesner (1991) on rats' memory

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