Module Three Flashcards
(178 cards)
What is the key difference between measurement and manipulation techniques in cognitive neuroscience?
Measurement techniques record brain activity to show co-occurrence with cognitive processes, while manipulation techniques disrupt brain function to test causal roles of regions.
Why can’t measurement techniques prove that a brain region is necessary for a function?
Because they are correlational, showing only that region activity co-occurs with the function, not that it is required for it.
What is the primary purpose of manipulation techniques?
To establish causal roles of brain regions by altering their function and observing resulting behavioral changes.
How do measurement and manipulation approaches complement each other?
Measurement identifies candidate brain–behavior associations; manipulation confirms causal roles, and together they strengthen inferences about neural mechanisms.
Which measurement technique provides millisecond temporal resolution and cellular spatial precision?
Single-unit recording (electrophysiology).
Which measurement techniques have intermediate temporal resolution (seconds to minutes) and spatial resolution (millimeters to centimeters)?
PET and fMRI.
Which techniques are considered low in temporal resolution (minutes to days)?
Pharmacological methods and lesion studies.
Which techniques offer high spatial resolution at the level of individual neurons?
Intracranial electrodes used in invasive neurophysiology (e.g., single-unit recording).
What spatial resolution do EEG and MEG typically provide?
Low spatial resolution on the order of centimeters to whole-brain measurements.
Why is no single method sufficient to capture all spatial, temporal, and causal aspects of brain function?
Because each technique has trade-offs in resolution, invasiveness, and causal inference, so converging evidence from multiple approaches is needed.
What does single-unit recording measure and how precise is it?
It measures action potentials (spikes) from individual neurons with millisecond temporal precision and cellular-level spatial precision.
What is the fundamental principle underlying single-unit recording?
Action potentials are voltage deflections when a neuron’s membrane potential exceeds a threshold (~+50 mV), each with a stereotyped amplitude and waveform.
What technology is used to place electrodes for single-unit recordings?
Insulated microelectrodes inserted via craniotomy, positioned using microdrives and stereotaxic coordinates.
Why are spike-sorting algorithms necessary in single-unit recording?
Because recorded signals may reflect multiple neurons, and spike sorting separates individual neuron activity from multiunit recordings.
What are the typical durations and outputs of single-unit recording sessions?
Sessions last minutes to hours, yielding raw spike trains over time and summary firing rates (e.g., peristimulus time histograms) across hundreds of trials.
What are two main advantages of single-unit recording?
It directly captures individual-neuron spikes and provides ground-truth data for neural circuit models.
What are two main limitations of single-unit recording?
It is highly invasive (craniotomy plus electrode insertion) and samples only a small number of cells at a time.
How does EEG measure brain activity and with what temporal resolution?
EEG detects synchronized postsynaptic potentials as voltage fluctuations on the scalp, providing millisecond-level temporal resolution but low spatial precision.
What are Event-Related Potentials (ERPs)?
ERPs are tiny, time-locked voltage shifts uncovered by averaging EEG traces around repeated stimuli, reflecting successive processing stages (perception, attention, etc.).
What hardware is involved in EEG signal acquisition?
Electrode arrays (from 2 to >128 channels), conductive disks connected by light wires, amplifiers sampling at 250–1000 Hz, and filters to reduce noise.
Why is spatial source localization difficult in EEG?
Because the inverse problem arises from volume conduction and scalp blurring, making it ambiguous to pinpoint underlying neural generators.
What are two main advantages of EEG?
Non-invasive, safe for repeated human studies, and provides millisecond temporal resolution of sequential processing stages.
What are two main limitations of EEG?
Poor spatial precision and lengthy setup to achieve low-impedance contacts.
How does MEG detect brain activity and what advantage does it have over EEG?
MEG tracks nano-weak magnetic fields from synchronized dendritic currents, providing millisecond temporal resolution and better spatial localization than EEG because magnetic fields are less distorted by the skull.