Learning and Memory 2 Flashcards
Do studies on animals have a relevance to humans?
LTP occurs in human brain tissue as well. This isn’t just specific to the hippocampus - happens in cells all over the brain. Wherever need to strengthen or weaken a synapse, LTP is there.
What are theta rhythms?
Hippocampal theta activity accompanies behaviours such as running, swimming, head movements and spatially orientated responses in the rat.
Seems to play a role in synchronising activity in different brain regions.
Is LTP physiological?
If do normal stimulation but at the peak of activity within the slice, you can get LTP – get same LTP as high frequency stimulation. If stimulate at the bottom, get LTD.
Things that are there consistently are more likely to be remembered, because activity occurs at the peak. Can understand at a molecular level because neurons are depolarised at peaks, means get enough NMDA activation to cause LTP.
Theta waves create an environment for LTP.
How can you enhance LTP?
Can enhance by genetic manipulation. Over-expressing sub-unti of NMDA receptor so have increased activity of neurons. Increase activity of receptors in these neurons. In a slice, see large change in LTP. With boost in LTP, are you going to see more learning and memory? – is a significant difference in the rate that they learn, but not as big of a difference when you inhibit LTP. When do the probe trial, spend significantly more time in the place where the platform was than anywhere else.
How does age affect LTP?
Decreased acquisition in the Morris Walter Maze. Big EPSP is much higher in the young mouse, whereas in the older there is some LTP but it is greatly reduced compared to the younger rat.
How can memory and LTP be enhanced?
See differences in rats/mice depending on whether they are in an enriched envionrment. This is because an enriched enviornment promotes neuro-plasticity, and the rats in the enriched enviornment are able to find the platform much more quickly. If look at LTP, see an increase in those mice that are reared in the enriched enviornment. This is an enhancement of the LTP process in isolated (not anything else).
Can the effects of aging be reversed by enrichment?
Spatial Maze Task - Aged mice in impoverished environment (IE) show greater deficits than those in normal (SE) or enriched environment (EE). Young mice (regardless of the environment) have learned the task reasonably. Older mice either in enriched, standard, or impoverished environment, in impoverished environment show a much poorer performance in this task (see deficits in learning and memory). Then changed the environment that they were living in, and tested them again – see those going from the impoverished environment to the enriched environment there is a dramatic change in their performance six weeks later. Not as good as those in the enriched environment all along, but they have dramatically improved their performance. This is evidence of why we should consider the environment of elderly people – e.g. loneliness will impact cognition.
What is associative LTP?
In a weak synapse, activation does not lead to an AP in the cell. If repeatedly stimulate the two pathways together, than this strengthens the weak synapse. Strong synapse - activation leads to an AP in the cell.
What is an example of LTP in the lateral amygdala.
Activation from an aversive event e.g. loud noise (neuron in somatosensory system) at the same time as activation from a tone (neuron in auditory system) leads to a fear reaction. Weak synapse (tone) only becomes stronger if the strong (noise) and weak are activate at the same time, and if there is depolarisation of the post-synaptic neuron.
What are neuronal mechanisms underlying conditioned fear?
Synaptic connections in the amygdala = ideal connectivity for long-term potentiation to occur. Conditioned stimulus information paired with unconditioned stimulus information results in a strengthening of the synapse, and after the conditioned stimulus alone triggers the lateral amygdala to fire and create a fear response.
If there proof that LTP underlies fear memories?
Way that can control activity of neurons by shining lights on them. Can do surgery and implant them into certain areas of rat brain into lateral amygdala neurons which think are in the pathways and flash light at them, therefore control how they respond under different conditions, and manipulate LTP to see what happens.
