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What has been displayed about the hippocampal formation?
What does the hippocampal volume represent?
What do it's functions include?
Which brain area represented egocentric or sensory centred space?
Which patient was unable to form new autobiographical memories?
Who studied them?
What did this patient improved performance suggest?
Where was the patients damage?
What did O'Keefe 1976 find in rats?
What are place cells?
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Crucial for spatial memory and autobiographical and episodic memory
Allocentric on environment centred large scale space
Navigations, spatial contexts, long-term memory for scenes and binds items in contexts
Parietal and frontal cortex
HM
Scoville and Milner 1950's
Performance improved on a tracing star task despite having no recollection of doing the task before - distinction between procedural memory and declarative memory
Hippocampus
Place cells
Cells that contain cognitive representations of specific locations in space
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What did O'Keefe and Nadel 1978 predict?
What did Lever et al 2002 do?
What did they find?
What is the interpretation?
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That the hippocampal formation would contain directional information
Single cell recording in the hippcampi of rats to measure the activation of 32 place cells
That cells firing together signal a specific location in a spatial context
That active cells in the hippocampus form the cognitive map and this map contains information about places connected by directions and distances
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What did Taub et al 1990 find?
What are they?
What did Hafting et al 2005 find?
What are they?
What is the basic unit of organisation in these cells?
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Head direction cells in the hippocampus
Neurons in the brain which increase firing rates above baseline levels only when the head point in a specific directions
Grid cells
Cells which have a grid like firing field which turns the whole environment into a mosaic
Evenly spaced equilateral triangles
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What did Barry et al 2006?
What do they respond to?
What are the different types of spatial neurons based on?(Two things)
What are grid cells?
What are boundary cells?
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Found border cells in the hippocampus
Presence of an environmental boundary at a particular distance/direction from an animal
Self motion as they determine movements need to be made by oneself to get to somewhere
External environmental as spatial instructions come from locations of surroundings
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What did Morris et al 1982?
What is it?
What did they find?
Interpretation:
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Morris water maze
Swimming round pool with milky water to find a submerged platform - Rats
Lesioned rats in the hippocampus after learning took longer and inaccurate routes
Hippocampus is important for spatial memory
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What did Maguire et al 1998?
What did they predict?
What did they find?
What kind of data?
What is the issue with this data?
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PET study that measured hippocampal activation when an individual located their way through virtual environments that they were familiar with
More hippocampal activity would lead to a more accurate path when asked to navigate the shortest route from A to B
The greater the right hippocampal blood flow, the higher the route accuracy, a positive correlation of hippocampal activity with navigation accuracy of 0.56
Correlational
Cannot determine whether high blood flow was due to taking the correct path or whether the individual was a better navigator
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What did Hartley et al 2003 do?
What did the study compare?
What was the subject asked to do?
What training were the participants given?
What did the study find?
What else did it find?
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fMRI to compare hippocampus activity in route and map representations
Way finding (following novel routes in one virtual town) with route following (following a well learned route in another town)
Find a way to an indicated location by the shortest route available, when each target was reached a new one was presented, the two towns were counterbalanced
They all had 15 minutes training, half did way finding (free exploration), half did route following (following a fixed route) 1 control with no training
A positive correlation between hippocampal activity and navigational accuracy of 0.74 this replicates Maguire et al 1998, also found better navigators used their Caudate less for way finding which is consistent with rat evidence that Caudate is more used for stimulus response journey and hippocampus is used for map based navigation
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What did Cornwell et al 2008 use?
What did they measure?
What are theta brain waves?
What tasks did they use?
What did they find?
What did Cornwell et al 2012 do?
What did it find?
What may be implied?
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Electro-physiology /MEG
Theta brain waves in the hippocampus of rats and humans
Morris water maze for rats and a virtual water maze for humans
Ff you record fromelectrodes into hippocampus, you find Theta during ratexploration of environment during human virtual exploration ofenvironment
Hippocampal theta power increases during water maze performance when navigating to a fixed location and hippocampal power at the beginning of the trail strongly predicts navigational accuracy
Repeated the study but added a condition where participants could receive random shocks during the trial to increase anxiety
Increased theta in those who were better navigators within the posterior hippocampus and that anxiety induced more theta in the anterior hippocampus
Anxiety increases theta, increased theta leads to better navigation, therefore it may possible be said that anxiety aids navigational skills
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What did Nadi et al 2013 find?
What did the study do?
What did Brown et al 2014 find?
What did Maguire et al 2000 do?
What did Maguire 2000 find?
What did Maguire 2011 find?
Are genetic predispositions likely to influence spatial mapping?
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Better map learners have large right hippocampi particularly the posterior hippocampus
Participants learned campus map over 3 weeks, map learning was measured by asking them to complete onsite and offsite direction/distance estimates and drawing a sketch map of the campus after the end of each guided route
Increased gray matter volume in the left and right hippocampus positively correlated with navigational accuracy
16 healthy, right-handed male licensed London taxi drivers. The taxi drivers were compared with the scans of 50 healthy right-handed males who did not drive taxis
The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and that the anterior hippocampal region was larger in control subjects than in taxi drivers. Hippocampal volume correlated with the amount of time spent as a taxi driver (positively in the right posterior and negatively in the right anterior hippocampus).
MRI right handed male taxi drivers learned the knowledge for 3 years and found in the brains of those who qualified that gray matter had increase in the right PC
Probably, genes may influence hippocampus plasticity levels
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