BLOA - explain effects of neurotransmission Flashcards
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
neurotransmitters
- 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
- OCD
- 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
- rats were trained to go through a maze and get to the end, where they received food
- 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 - 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
- neurotransmitters are stored in vesicles inside the axon
- vesicles exit the nerve cell via exocytosis, releasing the neurotransmitters into the synaptic gap
- 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)
- 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
- 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
