bio approach: excitatory Flashcards
definition of neurotransmitters
neurotransmitters are often referred to as the body’s chemical messengers.
they are the molecules used by the nervous system to transmit messages between neurons, or from neurons to muscles.
process of neurotransmission -
this is done when the presynaptic neuron releases chemicals called neurotransmitters to cross the gap between two neurons called the synapse. these neurotransmitters then bind to specific receptor sites on the postsynaptic neuron creating an electrical signal called the action potential.
if these receptor sites are blocked by another chemical the postsynaptic neuron will not be able to create an action potential, inhibiting the process of neurotransmission.
intro into excitatory neurotransmitters
some neurotransmitters are seen as more excitatory – that is, they make the target neuron more likely to “fire” an action potential.
a neurotransmitter can sometimes have either an excitatory or an inhibitory effect depending on the receptor sites that it binds to.
eg of an excitatory neurotransmitter -
an excitatory neurotransmitter which increases spatial memory is acetylcholine.
when acetylcholine binds to the ACh receptor in the post-synaptic neuron it improves spatial memory. thus, blocking the ACh receptors can inhibit the spatial memory.
study connected to this?
antonova et. al (2011) explains the role of acetylcholine in the encoding of spatial memory.
antonova et al. (2011) aim -
to test the role of acetylcholine in the encoding of cognitive maps in humans.
antonova et al. (2011) sample & set up
consisted of 20 healthy male adults (their average age was 28).
10 participants were given scopolamine (a drug that blocks acetylcholine receptor sites) and 10 were given a placebo.
this was given 70 – 90 minutes before the experimental task began.
arena task explanation: (procedure pt.1)
P put into an fMRI where they were scanned while playing the “Arena task.” complex virtual reality game in which the researchers are observing how well the participants can create spatial memories.
goal is for the participants to navigate around an “arena” to reach a pole.
aft they locate the pole, the screen would go blank for 30 seconds. during this time, the participants were told to actively rehearse how to get to the pole in the arena. when the arena reappeared, the participant was now at a new starting point in the arena. the participants would have to use their spatial memory to determine how to get to the location of the pole.
procedure pt.2
P were first trained in the game to make sure that they were comfortable with the use of the joystick and that they understood the rules of the game. after they were trained, they then took part in the experiment.
P brain activity was measured using fMRI while they engaged in the “Arena task” for six trials.
P returned for a follow-up session between 3 to 4 weeks later. during the follow up session, they underwent the same “Arena task” again but received the opposite treatment (participants who first got the placebo now got scopolamine and vice versa).
results -
researchers found that when the participants were injected with scopolamine, they took longer to find the “pole” than the group that received the placebo. P injected with scopolamine, demonstrated a significant reduction in the activation of the hippocampus compared to when they received a placebo.
conclusion -
it appears that acetylcholine could play a key role in the encoding of spatial memories in humans, as well as in rats.
from this study, we can understand how acetylcholine influences memory encoding by utilizing scopolamine, a drug that blocks acetylcholine receptor sites.
the observed effects on task performance and brain activity suggest that acetylcholine plays a vital role in facilitating the excitatory processes associated with the encoding of spatial memories.
