Chapter 5: RECORDING AND STIMULATING NEURAL ACTIVITY Flashcards
What electrical events can be recorded in neural activity?
- action potentials
- postsynaptic potentials elicited by terminal buttons
What electrical events can be recorded in neural activity?
- action potentials
- postsynaptic potentials elicited by terminal buttons
What can changes in electrical activity of a particular region be used for?
determine whether that region plays role in various behaviours
What are the two recording types for electrical activity ?
- chronological recordings
- acute recordings
What do chronological recordings consist of ?
-made over an extended period of time after animal recovers from surgery
What do acute recordings consist of?
- made for relatively short period of time during which the animal is anesthetized
- restricted to studies of sensory pathways
- doesn’t really involve behavioural observations because animal is not conscious.
Why do they measure electrical activity in particular regions?
changes in electrical activity of a particular region are used to determine whether it plays a role in various behaviours
What are microelectrodes?
Thin wires used to record activity of a single neuron
What are macroelectrode?
electrode used to record the electrical activity of large numbers of neurons in a particular region of the brain
How are changes in voltage detected by a macroelectrode plotted?
with EEGs (electroencephalograms)
What can EEGs be used for?
may be used to diagnose or treat patients
What does magnetoencephalography consist of?
-Detects groups of synchronously activated neurons by means of the magnetic field induced by their electrical activity
How does magnetoencephalography detect groups of synchronously activated neurons?
-Uses an array of superconducting quantum interference devices (SQUIDs)
How does the metabolic rate increase?
The metabolic rate increases with an increase in neural activity
How is the metabolic rate measured?
- By injecting radioactive 2-deoxyglucose (2-DG)
- Autoradiography visualizes the activity in the brain caused by the 2-DG
- Immunocytochemical methods identify cells containing Fos proteins
What is 2-DG?
A sugar that enters cells along with glucose but is not metabolized.
What is a autoradiography?
- Procedure that locates radioactive substances in a slice of tissue;
- The radiation exposes a photographic emulsion or a piece of film that covers the tissue
What is Fos?
A protein produced in the nucleus of a neuron in response to synaptic stimulation
What does functional imaging consist of ?
A computerized method of detecting metabolic or chemical changes in the brain.
What are the two types of functional imaging?
- Positron emission tomography
- Functional MRI (fMRI)
What is Positron emission tomography (PET) scan?
-A functional imaging method that reveals the localization of a radioactive tracer in a living brain.
What is an fMRI?
- functional imaging method
- modification of MRI procedure that permits the measurement of regional metabolism in the brain, usually by detecting changes in blood oxygen level.
Do fMRI or pet scans have higher resolution?
fMRI have higher resolution
How can we infer electrical activity from oxygen levels?
-Increased activity of a brain region stimulates blood flow to that region, which increases the local blood oxygen level.
What is the former name of fMRI’s ?
BOLD
How is electrical stimulation done?
Pass an electrical current through a wire inserted into the brain using stereotaxic surgery.
How is chemical stimulation done?
injection of an excitatory amino acid such as kainic acid or glutamic acid.
What is the main disadvantage of chemical stimulation?
-more complicated than electrical stimulation, because requires more equipment
What is the main advantage of chemical stimulation?
- It activates cell bodies not axons
- The effects of chemical stimulation are more localized and precise than electrical stimulation.
How is transcranial magnetic stimulation done?
Stimulation of cerebral cortex by means of magnetic fields produced by passing pulses of electricity through coil of wire placed next to skull.
How does transcranial magnetic stimulation affect the brain?
- interferes with functions of brain region that is stimulated
- treats symptoms of mental and neurological disorders
How do optogenetics methods work?
-use genetically modifies viruses to insert light-sensitive ion channels into the membrane of particular neurons in the brain.
What effects do optogenetics methods have on the brain?
- stimulate or inhibit selected populations of neurons in a specific brain region
- can depolarize or hyperpolarize neurons with mights of appropriate wavelength.
What are optogenetics used for?
-used to study functions of particular neural circuits in the brain
What happens when blue light strikes ChR2-ion channel?
- channels opens
- rush of positively charged sodium and calcium ions depolarizes the membrane, causing excitation.
What happens when yellow light strikes NpHR?
- proteins controls a transporter that moves chloride into the cell when activated by yellow light.
- influx of negative charges, hyperpolarizes membrane, causes inhibition.
