The basics of cognitive psychology Second lecture notes and reading. This lecture focused on the basics of cognitive psychology; the brain, neurons and brain imaging techniques.
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How do neurons process information?
How are faces represented by the firing of neurons?
How does brain change functioning to adapt to environmental
Stimulus stimulates receptors that change the stimulus into electrical
signals. These go throughout the brain in order to create responses. We also
receive knowledge and use knowledge throughout this process.
What are neurons?
Neurons are the building blocks and transmission lines of the nervous
system. There are around 180 billion of them in the brain.
How are these neurons organized?
How do they signal information about the environmental and create
actions in response to the environment?
•Make up the brain
•Transmit electricity and communicate with one another
•They are specialized to receive and transmit information from/to the
•Environmental energy is made into electrical energy for this
transmission of information to occur
Golgi: confirmed the existence of neurons by staining some neurons (leaving
most unstained) and seeing/figuring out the structure of single neurons.
Structure of Neurons
(1) Cell body: keeps cell alive
(2) Dendrites: branch out and receive signals
(3) Axon: transmits signals. This nerve fibre tube conducts electrical
(4) Sensory receptor: instead of cell body/dendrites. Receives information.
Neurons Respond To
(1) Light energy – vision
(2) Mechanical deformation – touch/pain
(3) Pressure change in the air – hearing/sound
(4) Air molecules – smell
(5) Liquid molecules – taste
What is TRANSDUCTION?
This is the process with which environmental energy is transferred into
electrical energy, or vice versa, electrical energy is transferred into
environmental energy. Within the nervous system is occurs when
environmental energy is converted into electrical signals that contain all the
information needed for a neuron to “work”.
*Recordings done from activity of single neurons provide a good number of
information about the brain and what is happening within it*
What are action potentials?
These are signals that have the transducted information. They are measured
via microelectrodes, which pick up signals as the potentials travel down the
neurons. These are recorded on an oscilloscope. The oscilloscope shows that
a neuron increases in charge/changes in charge/positively/negatively charged
for approximately 1 millisecond. It then returns to its original “resting” state.
On the oscilloscope, the nerve impulses look like spikes.
When the stimulus intensity is low, the neuron fires slowly.
When the stimulus intensity is high, the neuron fires quickly.
The size always remains the same. Therefore information about the
intensity of a stimulus is represented by the speed of firing not by the size of
the action potential.
(1) Action potential is propagated and travels from one of the axon to
another without decreasing in size.
(2) Travel very long distances
How do neurons communicate?
Neurons communicate with one another due to the synapse. The synapse is
a space between the end of an axon and the next neuron. This is where the
neurons communicate. Now the action potential itself does not travel across
(1) The action potential reaches the synapse
(2) It makes the synaptic vesicles burst and release neurotransmitters
(3) These neurotransmitters leave into the synaptic cleft
(4) Here, they flow down to the receptor sites of the postsynaptic neuron
(5) If there is a receptor that receives the released neurotransmitter, the
neurotransmitter goes into the receptor and into the new neuron
(6) It has two effects in the new neuron (the postsynaptic neuron). It either
(a) experiences excitation or (b) inhibition
(7) In the case of A, there is an increased chance of the postsynaptic
neuron firing the action potential.
(8) In the case of B, there is a decreased chance of the postsynaptic
neuron firing the action potential.
There are some neurons/neurotransmitters that cause A and others that
How do neurons process information?
There are approximately 80 billion neurons involved in cognitive processes.
Processing information by the nervous system is based on interactions
How do neurons interact with one another?
At the synapses, where one neuron releases a neurotransmitter into another
neuron. This is called neural processing. A number of neurons synapse
together and make a neural circuit.
What is a neural circuit?
This is a group of interconnected neurons.
(1) Convergence: a number of neurons send signals to one neuron
(2) Interaction of excitation and inhibition
Neurons respond to specific stimuli and sometimes respond best to a
certain type or size of stimuli.
The principle is that increasing intensity of stimulus will cause
excitatory synapses until the intensity is large enough to activate
The higher up you go in the brain, the more specialized the neurons
There are simple cells (respond best to bar of light will a particular
Complex cells (respond best to bars of light of certain orientation,
moving across retina in specific direction)
End-stopped cells (oriented bar of light with specific length or shaped
like a corner)
These three are called feature detectors. These are examples of neurons
that respond to more complex stimuli.
How are stimuli represented by the firing of neurons?
When looking at stimuli, the neurons fired contain information. That stands
for and represents the said stimuli. A neural code is information contained
within the neural firing for an object or experience.
What is the neural code for perceiving faces?
A particular face can be represented by a certain firing of neurons in the
temporal cortex. His applies to all experiences.
(1) Specific Coding: Firing of specifically turned neurons that are specialized
to respond to specific things. Neurons that are turned to respond to just one
specific stimulus. “Grandmother cell” (coinced by Lettoin). These
grandmother cells respond to specific stimulus.
However… there are too many things out there for each to have their own
neuron. Also, these grandmother cells respond to a certain number of specific
stimuli, such as all faces, or all high pitched sounds, etc.
Therefore particular objects are actually represented by the firing of
groups of neurons. A different pattern of firing across a number of neurons
is considered distributive coding (code for certain thing is distributed
across a number of neurons).
Stimulus stimulates receptors that change the stimulus into electrical signals. These go throughout the brain in order to create responses. We also receive knowledge and use knowledge throughout this process. Neurons are the building blocks and transmission lines of the nervous system. There are around 180 billion of them in the brain. Neurons: make up the brain, transmit electricity and communicate with one another, they are specialized to receive and transmit information from/to the nervous system, environmental energy is made into electrical energy for this transmission of information to occur. Golgi: confirmed the existence of neurons by staining some neurons (leaving most unstained) and seeing/figuring out the structure of single neurons. Structure of neurons (1) cell body: keeps cell alive (2) dendrites: branch out and receive signals (3) axon: transmits signals. This nerve fibre tube conducts electrical signals (4) sensory receptor: instead of cell body/dendrites.