Oscillations and Navigation - Holman Flashcards
Brain waves depend on…
a. behavioural state
b. time of the day
c. geometry of neurons
d. location of recording electrode
e. all of the above
f. a, c and d are correct
f- a, c and d are correct
Delta waves are characterised by a frequency of…
a. 1-3 Hz
b. 40-100 Hz
c. 0.1-3 Hz
d. 3-8 Hz
c - 0.1-3 Hz
Which of the following statements is/are false?
a. Theta oscillations are associated with rhythmic firing of interneurons in the basal forebrain which project to the hippocampus
b. theta waves are generated by interplay between excitatory and inhibitory neurons- pyramidal cells are rhythmically inhibited and receiving excitatory input
c. theta oscillations have a clear correlation with speed
d. Theta oscillations are associated with movement (theta activity during activity)
e. none of the above
c. theta oscillations have a clear correlation with speed
Explanation:
Theta waves do not always correlate with speed, however, they may be related to speed variance
Which of the following statements is/are correct?
a. gamma oscillations are very fast, 40-100 Hz oscillations
b. gamma oscillations are generated globally across large networks of pyramidal neurons
c. gamma oscillations are characterised by localised rhythmic firing and inhibition
d. gamma oscillations are unique to interneuron-networks and do not exists in networks involving pyramidal neurons.
e. gamma oscillations are associated with memory and higher cognitive functions
(a, c, e):
a. gamma oscillations are very fast, 40-100 Hz oscillations
c. gamma oscillations are characterised by localised rhythmic firing and inhibition
e. gamma oscillations are associated with memory and higher cognitive functions
place cells…
a. can respond to multiple locations in the environment, but fire at different intensities
b. respond to a single location in the environment by increasing their firing rate
c. place cells only encode specific spots in the environment, rather than represent the whole environment
d. place cells change their spatial representation overtime
e. b and d are correct
b. respond to a single location in the environment by increasing their firing rate
what are the characteristics of grid cells?
Grid cells:
- are pyramidal or stelate cells located in layer II of the medial entorhinal cortex
- fire symmetrically in an hexagonal manner
- quite stable overtime, but they shift instead of remapping when the subject moves
- Cells change firing rate in tessellated field (mosaic)
- based on egocentric cues (i.e. give information about the position of the subject in relation the environment)
- give info about the whole environment rather than about specific points in space
what are the characteristics of place cells?
Place cells:
- found mainly in CA1 area in the hippocampus
- respond to a single point in the environment by increasing their firing rate
- the whole environment is mapped by place cells, for any given point in space there is a place cell population that encodes it
- based on allocentric cues
- change between environments but stable over time
what are place fields?
Place fields are specific locations in space at which a place cell population is firing
what is a place-cell sequence? What may it tell us?
Concerted firing pattern of place cell nested within theta cycle in a predictable order.
–> the order in which place cells fire gives information about upcoming trajectory and future behaviour
–> Place cell sequences may be a model for the way items and places are associated with memory, as after the initial activation of the sequence, it can be replayed during memory consolidation.
what is the definition of theta phase precession? Which cells follow this phenomenon? when does it occur within theta oscillation? and what is its’ function? and why bother?
The firing phases of the corresponding place cell occur earlier and earlier relative to each theta cycle, as the animal travels through a place field.
–> there is a negative correlation between the spiking phase and animal’s location in a place field. i.e. the place cell’s firing phase shifts backwards as the animal moves forward
- -> found in both place and grid cells
- -> occurs at the gamma time scale
–> It organizes place-cell sequences during navigation
and TPP doubles the amount of info in a neural signal (Location can be deduced by how much a cell is firing (rate code) and when it is firing relative to the global LFP (temporal code).
also, Cells that fire close enough to one another to induce synaptic plasticity.
which of the following statements about theta phase precession is/are correct?
a. phase precession can be explained by the dual oscillator model and by the symmetric ‘ramp’ model
b. theta phase precession occurs in grid cells but not in place cells
c. phase precession can be explained by the dual oscillator model and by the asymmetric ‘ramp’ model
d. the firing phase of a cell is positively correlated with the animal’s location in a place field
e. a and b are correct
c. phase precession can be explained by the dual oscillator model and by the asymmetric ‘ramp’ model
T/F?
The advantage of theta phase precession, is that it increases the information content in the neural code and may explain behaviour-dependent synaptic plasticity
T
