CHAPTER 2: Cognitive Neuroscience Flashcards
What is happening inside Sven’s brain that makes it possible for him to hear the alarm, take appropriate action to turn it off, and know that he can sleep a little longer and still get to his early morning class on time?
- Hearing the alarm occurs when sound waves from the alarm enter Sven’s ears and stimulate receptors that change the sound energy into electrical signals
- These signals then reach the auditory area of Sven’s brain, which causes him to hear the ringing of the bell
- Then signals are sent from a number of places in the brain to the motor area, which controls movement. the motor area sends signals to the muscles of Sven’s hand and arm, which carry out the movement that turns off the alarm.
What is cognitive neuroscience?
The study of the physiological basis of cognition
What does cognitive neuroscience involve understanding…?
Involves an understanding of both the nervous system as well as the individual units that comprise that system
What experiments do we need to do to understand how the mind works?
both behavioural and physiological experiments
We do not examine topics of interest from a single perspective, but we look at them from _________ and different points of view.
multiple angles
what are neurons?
cells specialised to create, receive, and transmit information in the nervous system – small units that create and transmit information about what we experience and know
What do each neuron have?
cell body
axon
dendrites
What does the nerve net theory propose?
proposed that signals could be transmitted throughout the net in all directions.
What do the interconnections of neurons create?
a nerve net
The interconnections of neurons create a nerve net, which is like a continuous network that is similar to a ___?
…highway
– One street connects to another but without stop signs
– This allows for almost nonstop, continuous communication of signals throughout the network
what was the nerve net theory contradicted by?
the neuron doctrine
Who proposed the neuron doctrine?
Ramon y Cajal
what does the neuron doctrine propose?
the idea that individual nerve cells transmit signals, and are not continuous with other cells
Definition of cell body:
contains mechanisms to keep cell alive
Definition of Dendrites:
multiple branches of reaching from the cell body, which receives information from others neurons
Definition of Axon:
tube filled with fluid that transmits electrical signal to other neurons
How do neurotransmitters transfer?
Neurotransmitters (chemicals) are transferred from one neuron to the next at a synapse.
At any synapse, the transmission is in only one direction.
– One neuron is the sending neuron.
– The other neuron is the receiving neuron.
– Neurons can either excite or inhibit the neural actions of other neurons.
Definition of synapse
small gap between end of neuron’s axon and dendrites/cell body of another neuron
Definition of neural circuits
groups of interconnected neurons (form connections to specific neurons)
Definition of receptors
Specialized neurons to pick up information from environment.
how do neurons communicate?
(a) When the nerve cell is at rest, there is a difference in charge, called the resting potential, of –70 millivolts (mv) between the inside and outside of the axon. The difference in charge between
the recording and reference electrodes is fed into a computer and displayed on
a computer monitor.
(b) As the nerve impulse, passes the electrode, the inside of the fibre near the electrode becomes more positive.
(c) As the nerve impulse moves past the electrode, the charge in the fibre becomes more negative.
(d) Eventually the neuron returns to its resting state.
What is the process of action potential?
– Neuron receives signal from environment
– Information travels down the axon of that neuron to the dendrites of another neuron
Measuring action potentials
– Microelectrodes pick up electrical signal
– Placed near axon
– Active for 1 millisecond
how do neurons communicate using the synapse?
space between axon of one neuron and dendrite or cell body of another
When the action potential reaches the end of the axon, synaptic vesicles open and release chemical neurotransmitters
what are neurotransmitters and how do they work when neurons communicate?
chemicals that affect the electrical signal of the receiving neuron, cross the synapse and bind with the receiving dendrites
how is the action potential measured?
– The size is not measured; size remains consistent
– The rate of firing is measured
• Low intensities: slow firing
• High intensities: fast firing
When neurons are communicating, increasing the stimulus intensity causes?
an increase in the rate of nerve firing
What is “Principle of Neural representation”?
everything a person experiences is based on representations in the person’s nervous system.
“Principle of Neural representation” Gil’s conversation with Mary:
Gil sees Mary → light reflected from Mary enters Gil’s eyes → image is focused on retina (layer of neurons that lines the back of the eye) = a representation of Mary
Receptors in retina transform image into electrical signals → travel through retina → leave back of eye in optic nerve → visual cortex (area at the back of brain that receives signal from the eye)
how do action potentials determine different qualities?
the action potentials for each quality might look different.
example of magnitude of experience related to rate of nerve firing?
perception of a 100-watt light brighter than a 40-watt light bulb
what was the experiment Hubel & Wiesel conducted to determine which stimuli caused specific neurons to fire?
presented visual stimuli to cats
a) An experiment in which electrical signals are recorded from the visual system of an anaesthetized cat that is viewing stimuli presented on the screen. The lens in front of the cat’s eye ensures that the images on the screen will be focused on the cat’s retina.
b) A few of the types of stimuli that causes neurons in the cat’s visual cortex to fire.
What did Hubel & Wiesel conclude after they conduced the experiment presenting visual stimuli to cats to determine which stimuli caused specific neurons to fire?
found that each neuron in visual area of cortex responded to a specific type of stimulation presented to a small area of the retina.
What did Hubel & Wiesel call the neurons in the visual area of cortex responded to a specific type of stimulation presented to a small area of the retina?
feature detectors because they responded to specific stimulus features such as orientation, movement and length
Where is the first place that electrical signals from the eye reach the brain
situated in the visual cortex (back of the head)
What are feature detectors?
respond to specific stimulus features such as orientation, movement & length.
Where are feature detectors situated?
in the visual cortex in occipital lobe (first place that electrical signals from the eye
reach the brain)
neurons that respond to more complex stimulus features (geometrical shapes, hands buildings or faces) or to a combination of simple stimulus features (e.g. left-tilted line that moves to the right) are situated in the?
temporal lobe
who conducted an experiment to find out how complex stimuli are represented but the firing of neurons in the brain?
Charles gross
how did Charles gross conduct an experiment to find out how complex stimuli are represented by the firing of neurons in the brain?
recorded from single neurons in monkeys temporal lobe (on the side of the brain).
he presented monkeys with lines, squares, and circles (some were light, some were dark).
The shapes are arranged in order of their ability to cause the neurons to fire, from none (1) to little (2 and 3), to maximum (6). Thus, the more the shape looked like a thin hand with fingers pointing upwards, the more the neurons started firing.
What did Charles Gross conclude from his experiment regarding how complex stimuli are represented by the firing of neurons in the brain?
found a neuron that refused to respond to any of the standard stimuli (i.e., the bars, circles and squares)⇒ respond to hand like shape with finger pointing up.
After expanding the types of stimuli presented and the place of recording, researchers also found some other
neurons in the temporal lobe that responded best to faces, but didn’t respond to other types of complex stimuli like hands or buildings.
neurons in the visual cortex respond to?
respond to simple stimuli like oriented bars;
neurons in the temporal lobe respond to?
respond to complex geometrical stimuli; and
neurons in another area of the temporal lobe respond to?
respond to hand shapes or faces.
Neurons in the visual cortex that respond to relatively simple stimuli send their axons to?
higher levels of the visual system, where signals from many neurons combine and interact;
Neurons at this higher level, which respond to more complex stimuli such as geometrical objects send signals to ?
higher areas, combining and interacting further and creating neurons that respond to even more complex stimuli
what is hierarchical processing
when we perceive different objects, we do so in a specific order that moves from lower to higher areas of the brain
The ascension from lower to higher areas of the brain corresponds to perceiving objects that move from lower (simple) to higher levels of complexity
definition of Sensory code:
how neurons represent various characteristics of the environment.
Problem of sensory coding?
problem of neural representation for senses. How does the nervous system send information that results in a rich perception? So, trying to understand how the neurons in our brain activate to stimuli in our outside environment that we sense. E.g., which neurons activate if we see a tree? We don’t know exactly how this works.
what is specificity coding?
The representation of a specific stimulus by the firing of neurons that respond only to that stimulus.
definition of population coding:
neural representation of a stimulus by the pattern of firing of a large number of neurons.
advantage of population coding:
large number of stimuli can be represented
Definition of sparse coding:
neural coding based on the pattern of activity in small groups of neuron. so when a particular object is represented by a pattern of firing of only a small group of neurons, with the majority neurons remaining silent.
Where did early evidence for localisation of function come from?
neuropsychology
What is localisation of function?
specific functions are served by specific areas of the brain
what is neuropsychology?
the field of psychology that aims to understand how behaviour and cognition are influenced by brain functioning and that is concerned with the diagnosis and treatment of people with brain damage
What is the cerebral cortex?
3mm thick layer that covers the brain – contains mechanisms responsible for most of our cognitive functions
Where is the frontal lobe located?
Front of head
Where is the Temporal lobe located?
Sit behind the ears on the sides of head
Where is the parietal lobe located?
Near the back on top of the head
Where is the occipital lobe located?
back of the head
the hemispheric division of the brain has strong implications for ?
cognitive behaviours
What is the left hemisphere responsible for?
language and analytic thought
What is the right hemisphere responsible for?
spatial & perceptual relations, creativity
visual stimuli, like most sensory information, is processed _______ to the _______
contralateral to the visual field.
What does it mean that visual stimuli like most sensory information is processed contralateral to the visual field?
information from the left visual field is processed in the right hemisphere of the brain and information from the right visual field is processed in the left hemisphere of the brain.
What results were found when contralateral processing is paired with hemispheric specialisation?
shapes presented in the right visual field (left hemisphere) may take longer to identify than shapes presented to the left visual field (right hemisphere), while words presented on the left visual field may take longer to process than those presented to the right visual field.
The two hemispheres in the brain differ in their specialisation: TRUE or FALSE?
TRUE
Is information shared between the brain’s right and left hemisphere in split-brain patients?
no
What are split brain patients?
split-brain patients had a operation that surgically severed the corpus callous (broad band of neural fibres that connect the two hemispheres)
has research shown linguistic advantage in the right or left hemisphere?
left hemisphere
has reproach show that manual tasks has an advantage in the right or left hemisphere?
right hemisphere
Split brain patients have undergone surgery to cut?
the corpus callosium
is the right or left hemisphere dominant for verbal processing?
left hemisphere
What happened with split brain patients were shown the word face in their right visual field?
as the left hemisphere is dominant for verbal processing the patients gives the correct answer
what happened with split brain patients were shown the word face in their left visual field?
since the right hemisphere cannot share information, the patient cannot say they see face but rather the can draw it.
What happens when a brain is damaged because of a stroke?
disruption of food supply to brain (usually cause by blood clot)
What did Paul Broca (1861) study?
He studied a patient who had suffered damage to his left frontal lobe who had difficulty with talking and could only say the word “tan”
What did Paul Broca suggested about the study he conducted of a patient who had suffered damage to his left frontal lobe?
Suggested that the area in the left frontal lobe is specialised for speech, production language
Function of parietal lobe?
processes information about temperature, taste, touch and movement, interprets language, hearing
Function. The parietal lobe is vital for sensory perception and integration, including the management of taste, hearing, sight, touch, and smell. It is home to the brain’s primary somatic sensory cortex, a region where the brain interprets input from other areas of the body.
function of the frontal lobe?
important for cognitive functions and control of voluntary movement or activity. Personality, behaviour, emotions, planning, problem solving, speech, writing, body movement, intelligence, concentration
function of occipital lobe?
primarily responsible for vision. interprets vision (collar, light, movement)
function of temporal lobe?
processes memories, integrating them with sensations of test, sound, sight, and touch, understands language, hearing, memory
Function of the cerebellum?
its function is to coordinate muscle movements, maintain posture, and balance
Function of Brain stem?
acts as a relay centre connecting the cerebrum and the cerebella, to the spinal cord. performs automatic functions such as breathing, heart rate, body temperature, etc.
Where Is the cerebellum located?
under the cerebrum
Function of cerebrum?
largest part of the brain and is composed of the right and ;eft hemisphere. it performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement
What did Carl Wernicke study?
Patients with damage in an area of the temporal lobe
patient where speech was fluent and grammatically correct but tended to be incoherent
What did Carl Wernicke suggest about the patients he studied with damage in an area of the temporal lobe?
suggested that the part of the temporal lobe that was damaged in these rationed is responsible for Language comprehension.
Where is language production (speech) impaired by damage to?
Broca’s area (frontal lobe)
Where is language comprehension is impaired by damage to?
Wernicke’s area (temporal lobe)
Where is the primary receiving area for the sense vision?
occipital lobe
Where is the primary receiving area for the senses touch, temptation, and pain?
parietal lobe
Where is the primary receiving area for the senses hearing, taste, and smell?
temporal lobe
