m. a. wilson and b. l. mcnaughton presented by: katie herdman, monika walerjan, scott good, snir...
DESCRIPTION
Hippocampus (HC) HC role in memory encoding is extensively documented HC has long been considered important for cognitive representations and associative memory The notorious Morris Water Maze proved similar activation of the HC - Introduction - Methods - Results - Discussion Katie HerdmanTRANSCRIPT
M. A. Wilson and B. L. McNaughton
Presented by: Katie Herdman, Monika Walerjan, Scott Good, Snir Seitelbach and David Dudar
Presentation Outline Introduction
Hippocampus Place Cells Purpose of the Experiment
Methods Apparatus Data Analysis
Results Findings Inhibitory Interneurons Repeat Trials
Discussion Conclusions
Katie Herdman
Hippocampus (HC) HC role in memory encoding is
extensively documented HC has long been considered important
for cognitive representations and associative memory
The notorious Morris Water Maze proved similar activation of the HC
- Introduction- Methods- Results- Discussion
Katie Herdman
Place Cells HC is the home of “place cells” Place Cells fire when the individual is
in a physical environment that the cell is responsible for
Place cells require active movement through the environment
- Introduction- Methods- Results- Discussion
Katie Herdman
Purpose of the Experiment To determine if cell population activity over
brief intervals is a robust indicator of spatial location
To address the role of experience in the establishment of hippocampal spatial representations
To determine whether incorporation of new spatial information has any effect on previously stored information
- Introduction- Methods- Results- Discussion
Katie Herdman
Methods 3 rats implanted with microdrive arrays
containing 12 four-channel recording electrodes (tetrodes)
Each tetrode resolves activity from 5-20 hippocampal neurons
- Introduction- Methods- Results- Discussion
Scott Good
The Apparatus Rectangular box used, 124cm x 62cm x
62cm Walls were covered with a variety of
visual and tactile cues Two areas, called Box A and Box B,
were separated by a partition
- Introduction- Methods- Results- Discussion
Scott Good
The Apparatus ctd. During test period, tetrodes recorded for
10 minutes while rats explored Box A Partition was removed, neuronal
recording during exploration of Box B
- Introduction- Methods- Results- Discussion
Scott Good
The Apparatus ctd. Partition returned, recording continued
for 10 minutes afterwards in Box A Recordings were divided into
appropriate phases; 1-4
- Introduction- Methods- Results- Discussion
Scott Good
Data Analysis The rats’ trajectories
were plotted and computed
Each square represents spatial activation of one particular cell
Depending on what cells were activated, the experimenters could predict the location of the rats in the box
- Introduction- Methods- Results- Discussion
Scott Good
Findings The longer the integration time, the less
cells are needed to predict rats location accurately
Spatial representations involve many HC cells working together, rather than just one or two
- Introduction- Methods- Results- Discussion
Snir Seitelbach
Findings ctd. Error estimating rat location was greater
than 5cm due to intrinsic tracking error
- Introduction- Methods- Results- Discussion
Snir Seitelbach
Findings ctd. Different place cells are activated during
different situations Inhibitory interneurons were activated,
inhibited other hippocampal neurons Inhibitory interneurons allow certain
place cells to fire while inhibiting others, key role in forming spatial maps
- Introduction- Methods- Results- Discussion
Snir Seitelbach
Inhibitory Interneurons When open to Box A and B, inhibitory
interneurons were suppressed Hypothesized to be synaptic
modification to a new environment Indicates necessity for HC place cells to
gradually acquire cognitive representation
- Introduction- Methods- Results- Discussion
Snir Seitelbach
Effect of Experience Little effect on firing
of place cells New spatial
knowledge did not interfere with prior spatial knowledge
- Introduction- Methods- Results- Discussion
Snir Seitelbach
Conclusions
- Introduction- Methods- Results- Discussion
Snir Seitelbach
One can predict the location of the rats in a box based on firing of hippocampal place cells
New spatial representation expression improved rapidly with experience; the assumed synaptic modification mechanisms are rapid
Inhibitory interneuron suppression might facilitate the synaptic modification involved in encoding novel spatial information
Interference between new spatial information and prior spatial knowledge was very small
Significance Complexity of hippocampus function and
its general significance
- Introduction- Methods- Results- Discussion
Snir Seitelbach