Flashcards
Computational Neuroscience 2
Cards in this deck (38)
- 1what is the generalised function of the hippocampus?memory
it belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation - 2where is the hippocampus located?the hippocampus is located under the cerebral cortex; and in primates it is located in the medial temporal lobe, underneath the cortical surface
- 3what can the Cornu Ammonis (CA) be divided into?4 regions
CA1-->CA4 - 4what does dentate mean?white teeth
- 5what is 'special' about the dentate gyrus?one of the few areas of the adult brain that exhibits neurogenesis
- 6—x
- 7what is the function of the entorhinal cortex?The EC is the main interface between the hippocampus and neocortex. The EC-hippocampus system plays an important role in declarative (autobiographical/episodic/semantic) memories and in particular spatial memories including memory formation, memory consolidation, and memory optimization in sleep
near the smell processing area
not part of the hippocampus - 8what do we mean by DG = feedforward?lack lateral connections - connections between themselves
- 9CA3 = recurrent networks?excitatory neurons are interconnected
- 10can the hippocampus be said to be the junction between the limbic system and the cortexyes
limbic system = emotions
cortex = reasoned decision making - 11what type of memory is medium 'term'?DECLARATIVE - the sort of memory that can be desired in words
hippocampus is important for medium-term memory - 12are long-term memories stored in the hippocampus?no, outside in the (cortex?)
- 13flip/carry on to work out
- 14DG --> CA3?mossy fibres
- 15EC --> DG?perforant pathway
- 16CA3 --> CA1?perforant pathway
Schaffer collaterals - 17what does the loop on the CA3 represent?the high level of recurrent connections in that region
- 18what are place cells and where are they found?hippocampal pyramidal neutrons that fire/become active when an animal enters a particular place (place field)
navigation (london taxi drivers) - 19what is adult neurogenesis? what is responsible for this?new neurons born in adult mammals
dentate gyrus - 20what are the 2 main types of cell in the dentate gyrus?1) granule cells - excitatory
2) basket cells - inhibitory
granule cells project onto CA3 - 21in the dentate gyrus (feedforward) what connections are there between the two cells?no connections between granule and granule
inhibitory and excitatory (granule-basket) cell connections are present however - 22are CA3 pyramidal cells 'recurrent' and connected to each other?auto-associative network
- 23what is artificial intelligence in computer science based on?auto-associative network (doesn't work)
- 24—able to retrieve a piece of data from only a tiny sample of data
- 25what type of neurons is the CA3 made up of in the model? what states could the possess?Mcculloch-Pitts neurons
binary state:
active/on = 1
inactive/off = 2 - 26—x
- 27during learning the patterns are activated and plastic changes are made to the synapse strength according to a simple correlation based Hebbian plasticity ruleN = number of neurons
Xi = activity of neuron i
Wij = strength of connection from i to j
a = the average proportion of neurons active at any time
N (italics) = learning rate
- 28—neuron 5 is involved in tow patterns and, as a consequence some of its connections are strengthened for one patter and weakened for another
- 29if N = number of neurons then what is the symbol for number of connections?N^2 of the 'Wijs'
- 30to store a pattern..?the capacity is proportional to the number of neurons
a memory is a patternnof 1s and 0s over their neuron - 31when many patterns are stored, it is likely that there will be interference between them. what does too much overlap mean?too much overlap prevents retrieval
- 32—x
- 33—
- 34banana analogy?'we don't store the idea of a bent, stick-out yellow 'banana', we store some coded version of it'
this code is produced in the dentate gyrus - 35how do Matt Jones think we prevent confusing similar patterns?we randomise the patterns before we STORE THEM IN THE CA3
new neurons come in and sprout connections --> consistent with neurogenesis in DG - 36so, in summary, what can we say the role of the dentate gyrus is?randomise the connectivity between EC and CA3
during learning, neurons in EC and CA3 are matched via. DG and that the connections from EC - DG and DG- EC are essentially RANDOM - 37what is an auto-associative memory?all memories that enable one to retrieve a piece of data from only a tiny sample of itself
- 38summary?the sample model that CA3 is an auto-associative memory store and DG = a feedforward network that passes the pattern along, but randomises it a bit on the way to help keep similar patterns separate
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- 2nd Year Techniques in Neuroscience (Circuits and Behaviour) Flashcards on Computational Neuroscience 2, created by William Chapman on 23/05/2016.
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