Lecture 18- Methods in Cognitive Neuroscience Flashcards
What is Cognitive Neuroscience?
• Cognitive neuroscience is a branch of neuroscience that focuses on brain function and brain
dysfunction (neuropsychology) on a cognitive level.
• Cognitive neuroscientists relate behaviour to brain function.
What is Cognitive Psychology?
• Cognitive psychology is a branch of psychology that focuses on complex mental processes, such as
perception, learning, and memory.
• Cognitive psychologists study mental processes (e.g., how people focus their attention) and
information-processing problems (e.g., bottlenecks and limitations).
What is a bottleneck?
-When we focus on particular thing
-Miss important information coming in from another source
- Cause we can only process so much at one time: information just doesn’t go in (in earshot but no conscious awareness)
What are the common tools used in cognitive neuroscience?
• Brain lesion analysis (neuropsychology research)
• Electroencephalography (EEG)
– Event-related potentials (ERPs)
• Functional brain imaging
– Positron emission tomography (PET)
– Functional magnetic resonance imaging (fMRI)
• Transcranial magnetic stimulation (TMS)
What is brain lesion anaylsis?
• This method of research aims to uncover how the brain normally functions by investigating the
behaviour of a patient with a brain lesion in a specific region.
• Brain lesion analysis involves comparing people with a brain lesion in the region of interest (ROI)
with people in which the ROI is intact.
– Experimental Group: Participants are selected based on having a brain lesion in the ROI.
– Control Group: Participants are selected based on not having a brain lesion in the ROI.
• Patients can be screened for whether they have a brain lesion in the ROI using structural
neuroimaging.
• If a specific brain structure is hypothesized to perform a particular mental operation, then damage to
that brain structure should be associated with deficits in performing tasks that rely on the mental
operation.
What is Electroencephalography (EEG)?
• EEG provides a recording of the brain’s electrical activity.
• Electrodes are attached to the surface of the scalp.
• The signal detected by each electrode is amplified and recorded.
• Predictable EEG patterns occur during different behavioural states.
• Because normal EEG patterns are consistent across individuals, EEG recordings can detect
abnormalities in brain function (e.g., seizure activity).
What are Event related potentials?
• ERPs are based on electroencephalography (EEG).
• The EEG recording is time locked to an event.
• The EEG trace that is elicited by an event is called an ERP (i.e., a signature of the electrical activity
that occurred in the brain in response to a specific event).
• The EEG traces associated with each event are averaged across many trials such that the background
noise is removed and the electrical response to the event can be observed.
• The averaged EEG traces are then compared (e.g., averaged EEG activity when Stimulus A occurred
vs. when Stimulus B occurred).
ERP research considers electrical activity in response to an event in terms of:
– Latency
– Amplitude and Polarity (positive or negative)
– Scalp Topography
Is the spatial resolution of ERPs accurate?
Because ERPs are recorded from the scalp, when electrical activity is generated from a central brain structure, it is difficult to determine which structure was active. Consequently, the spatial resolution
of ERPs is not very accurate.
What type of resolution are EPRs good for?
In contrast, ERPs provide a good account of the timing of brain activity (i.e., the temporal resolution
is quite accurate).
What are the different types of Neuroimaging? What fits into each category?
Neuroimaging falls into two broad categories: structural imaging and functional imaging.
– CT, MRI and DTI provide structural images of the brain.
– PET and fMRI provide functional images of the brain.
What are the three types of structural imaging?
Computed tomography (CT) uses X-ray technology to produce a series of brain images, enabling the
structure of the brain to be viewed.
• Magnetic resonance imaging (MRI) was invented more recently and produces brain images with
much higher resolution.
• Diffusion tensor imaging (DTI) provides a view of white matter tracts (i.e., axons) using an MRI
scanner.
What is Positron Emission Tomography (PET) ?
A PET scanner detects radioactive material.
• Participants either inhale or are injected with a radioactive material.
• When the radioactive material gets into the bloodstream, it goes to areas of the brain that are
metabolically active.
• The PET scanner provides an image of the concentration (and distribution) of the radioactive
substance, thus showing a functional view of the brain.
What is Functional Magnetic Resonance Imaging (fMRI)?
fMRI is an adaptation of MRI that records changes related to metabolic activity in successive images
in order to produce a functional view of the brain.
• fMRI is a sensitive method for measuring neural activity that has considerably greater spatial
resolution than PET scanning.
What is Transcranial Magnetic Stimulation (TMS)?
• TMS is a non-invasive method that causes a transient disruption of brain activity by emitting a brief
magnetic pulse. The disruption can be excitatory or inhibitory.
