L9 Hippocampus pt 1 Flashcards
What are the 2 main functions associated with the hippocampus?
Rapid place and declarative learning
Behavioural control - cognitive, emotional, sensorimotor networks
Which of these might be an example of one trial rapid place learning?
A A rat learning his way through a maze after trial and error
B Remembering where you parked your car in a carpark you have never been in
C Remembering your way back to the hotel from the irish bar on the first night of your holiday
D Both B and C
D both B and C
In the case study of HM, and other hippocampal lesions, there was shown deficits in ____________ memory such as recall of __________ memories, and deficits in _______ and ________ memory. However, other types of memory such as ___________ was often spared, and so was intellect.
Hippocampal lesion deficits - declarative memory such as episodic memories recall, place memory and contextual memory.
Relatively spared semantic and procedural memory.
What is the main deficit of a total hippocampal lesion in rats, shown in what task?
Shown in the watermaze task, where rats use place memory to search for a target, hippocampal lesions cause clear deficits in place memory - longer time taken for target, target preference same as non target controls.
True or false, despite hippocampal lesions, rats can achieve place learning incrementally
True
Just as rats with hippocampal lesions were able to slowly __________________________________________, HM was also able to incrementally ________________________________________________. This suggests the specific role of the _______________ in _________ place learning.
Rats can slowly acquire place learning in watermaze task, just as HM was able to gain place memory for the layout of his house, after some time. Shows specific role of hippocampus in rapid place learning
Okeefe, 1998, 1971, (2014 nobel prize), showed what would happen in the hippoccampus when a rat was in a different place on a spacial scene.
Discovery of place cells - different parts of the room, different nerve cells in the hippocampus would fire - higher firing in some place memories more specific than others
Other than place memory, what feature of hippocampal firing was found in rats (Wood et al, 2000)?
A Semantic memories for objects they recognized
B Procedural memories for whisker burshing actions
C Route specific memories for alternating trial routes
D All of the above
C Route alternating memories
Using oppurtunisitc single cell recordings in humans with epilepsy, ________ cells for areas in a virtual environment, and firing of __________ and _________ of specific ________ in a movie clip, showing cell specific ________ and ________ memory in humans.
Single cell recordings in humans have shown:
- place cells firing at different areas in a virtual environment, showing place specific spatial memory
- Same firing in encoding and recall of movie scenes, showing episodic memory
Which brain region precedes the hippocampus, funneling through sensory and cortical input?
A Insular cortex
B Amygdala
C Anterior cingulate cortex
D Entorhinal cortex
D Entorhinal cortex
What is Hebb’s rule of synaptic connection strengthening?
Things that fire together, wire together - repeated firing and association of things causes long term strengthening of connections
What is the underlying process in the hippocampus called that allows for new synaptic connections to form?
Long Term potentiation
Brifely describe the process of Long term potentiation
Neuronal firing, causes the release of glutamate from presynaptic terminal. At post synaptic receptor site, 2 main receptors: AMPA and NMDA. AMPA receptors are permeable to sodium ions, allowing them to pass through, but at NMDA receptor, gluatamte binds, but calcium ions cannot pass through due to magnesium blockade.
Larger repeated signals cause sodium ions to pass through AMPA receptor and lead to depolarization of post synaptic receptor site. This leads to electrostatic repulsion of magnesium blockade at NMDA receptor. This allows calcium ions to pass through, and LTP to occur.
Calcium intake allows for increase in number and efficiency of AMPA receptors, in short term, and in long term leads to strengthening of new synaptic connections.
What would a hippocampal NMDA receptor antagonist have an effect on (Morris et al, 2016 brain prize)?
A Would effect baseline neurotransmissions, with intact long term potentiation
B Would block the formation of place memories
C Would effect long term potentiation only, and basleline neurotransmission would be spared
D Both B and C
D both B and C
There is debate over whether memory storage and subsequent retrieval is _______________ _______________ on the hippocampus, or whether the hippocampus is only required in _________________.
debate over if retrieval of stored memory permanently dependent on hippocampus, or does hippocampus have a role in consolidation
During encoding, presentation of stimuli evokes a ________ of __________ in cortical areas, which activate hippocampal neurons. Repeated associations lead to __________ ____________ between hippocampal neurons and other hippocampal neurons, as well as _________ _______.
Stimuli evoke activity pattern in neocortex, activating hippocampus.
Repeated associaitons cause new synaptic connections within hippocampus and bewteen hippocampus and cortical areas.
It is thought that in retrieval, presenting part of a configural setting evokes the original __________ _________ from cortical areas to the hippocampus, where the original _________ ________ is activated.
Presenting part of configural pattern evokes synaptic connections with hippocampus, which then generates the whole configural pattern
How did BAST et al show one trial place learning task, when affected by different receptor antagonists?
In encoding had to learn spatial area of a star, and retrieval had to dig star up.
Given AMPA and NMDA receptor antagonists, before retrieval, or after retrieval and before encoding, to see which is effected.
Bast et al showed that NMDA receptor antagonists effected what?
NMDA receptor antagonists effected encoding, but not retrieval. One trial place memories effected when given before encoding only, but not retrieval.
Bast et al showed that AMPA receptor antagonists effected what?
AMPA receptor antagonists effected encoding and retrieval. When given before encoding, learning effected, as well as when given before retrieval.
What is true of the effects of NMDA and AMPA receptor antagonists on encoding and retrieval?
A AMPA receptors are only important for encoding, and not retrieval.
B NMDA receptors are only important for encoding, and not retrieval.
C AMPA receptors are important for both encoding and retrieval
D Both B and C
D AMPA for retrieval and eoncoding
NMDA just for encoding
Electrophysiological evidence on the seperate effects of NMDA and AMPA receptor blockers revealed AMPA blockers effect _____________ ______________, whereas NMDA blockers effect the induction of _____, but not its ___________.
AMPA blockers effect baseline neurotransmission
NMDA blockers effect induction of LTP, but not its maintenence
Deficits in rapid place learning and episodic memories, and altered hippocampal neural circuitry, have been associated with:
A Age related memory decline
B Mild cognitive impairment (MCI)
C Alzheimer’s
D All of the above
D All of the above
Age related memory related hippocampal alterations such as Alzheimer’s and MCI have been generally been associated with ___________, whereas Schizophrenia and depression related hippocampal dysfunction has been related to ________________
Age related hippocampal dysfunction - hypo-metabolism in hippocampus, reduced
SZ or depression hippocampal dysfunction related to hyper-metabolism
True or false, recent research has shown hyperexcitability in the hippocampus as well as hypometabolism in age related memory declines
True
Disordered attention, memory and executive function falls under which category of Schizophrenia?
A Cognitive symptoms
B Psychosis (positive)
C Negative symptoms
D None of the above
A cognitive symptoms
Heckers showed that there is __________ hippocampal volume in people with SZ, showed hippocampal ______________ at rest, but _______________ hippocampal ____________ during a memory task. Diercks et al showed ___________ hippocampal activity during audtory hallucinations.
In SZ people, findings such as:
Decreased hippocampal volume
Increased or overactivity at rest
impaired recruitment in memory task
Increased activity related to auditory hallucinations
The current theory into the range of findings on the hippocampus in Schizophrenics what?
A Underactivity of hippocampus in early life may lead to reduced hippocampal volume (atrophy) in later stages as a result of dysfunction
B Underactivity of hippocampus in early life may lead to increased hippocampal volume (hypertrophy) in later stages due to dysfunction
C Overactivity of hippocampus in early life may lead to decreased hippocampal volume (atrophy) in later stages due to excitotoxicity
D Overactivity of hippocampus in early life may lead to increased hippocampal volume (hypertrophy) in later stages due to excitotoxicity
C Overactivity causes excitotoxicity induced reductions in volume is the current theory.
At a pharmacology level, Hippocampal overactivity may be due to reduced ___________ ___________ as a result of disrupted ________ receptor functioning.
May be due to reduced neuronal inhibition as a result of disrupted GABA receptor functioning
What key piece of evidence suggests this reduced GABAergic inhibition in the hippocampus?
Post mortem revealed reduced presynaptic GABA markers
People with schizophrenia often show deficits in _________-related learning abilities, such as _______ learning. In terms of positive symptoms, _____________ may be an effect of random activation of ____________ dependent memories
SZ people can show hippocampal related learning deficits such as place learning.
Hallucinations may be an effect of random activations of memories in hippocampus
