IB Psychology HL - BLOA - Explain Effects of Neurotransmission

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

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)

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

to investigate how sensory deprivation affects the brain

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

serotonin levels increased in the monks’ brains

sensory deprivation causes the release of serotonin

- the higher levels of serotonin activated the hypothalamus and frontal cortex, resulting in hallucinations

gender imbalance: as only men were used, caution should be used when generalizing to women

very culturally specific (Japanese monks)

To investigate the effect of serotonin on attraction and OCD

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

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

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

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

investigate the role of acetylcholine on memory

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

rats with lower acetylcholine were slower

- higher acetylcholine group finished the maze and found the food more quickly, and took fewer wrong turns

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

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

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

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