17 Neural Representations Flashcards
What is synaptic transmission
Neuronal Communication
What is an action potential?
With a rapid change in the voltage of the cell’s membrane
when an action potential occurs, the nerve is said to have fired.
Terminology: the neuron fired at a rate of 10spikes/sec (i.e 10 action potentials/sec
Action potentials can be elected artificially
What normally causes action potentials?
Sufficient input can trigger an action potential
For example, moving a whisker on a rat can cause somatosensory neurons to fire rapidly.
what is Single Cell Recording
Single-cell recording involves recording action potentials from an individual neuron.
Using single-cell recording, we can measure the activity of an individual cell while different stimuli are viewed.
Also which types of stimuli cause a neuron to fire action potentials
The receptive field in response to single cell recording
All visually sensitive cells only respond to stimuli in a limited region of space
This region of space is referred to as that cell’s receptive field (demarcated by the dashed circle in the figure).
how was a Map of neural activity (population of neurons) formed through experimenting on a monkey?
While viewing a stimulus the monkey was injected with a radioactive agent
Metabolically active cells in the primary visual cortex absorbed the agent, revealing that the organisation of the cells in this area of the cortex represents the visual field.
How many neurons participate in the representation of a single visual image?
Functional imaging techniques such as fMRI provide an opportunity to explore the issue because they allow the simultaneous detection of the entire neuronal population responding to each stimulus.
fMRI is an adaption of MRI that records changes related to metabolic activity in order to produce a functional view of the brain
The signal from fMRI is approximately proportional to neuronal activity, this method can be used to better estimate the number of neurons involved in a specific cognitive process
Research recently scanned the visual cortex while the patient viewed an image –> at least two hundred million neurons are involved in the representation of a single memory.
What is a tonotopic map?
The frequency tuning properties of the cell define a tonotopic map
Topographic maps are also seen in the primary motor cortex and primary somatosensory cortex.
The activity of many neurons in the olfactory bulb was recorded and different scents evoked different spatial patterns of neural activation
