This preview shows page 1. Sign up to view the full content.
Unformatted text preview: o very slowly - continue to
signal as long as the stimulus is present. 59 General principles of sensory
coding - 4
Coding of sensory modality:
We perceive different kinds of sensations because
the different types of receptors (listed below)
maintain a specific set of connections that ultimately
stimulate brain regions that are primarily dedicated
to each modality (the labeled-line principle). Sensory receptors are
kinds of external
stimuli into a biological
signal and represent
the starting point for
modality coding in the
nervous system. 60 Techniques for Studying Brain Function:
Involves recording the electrical activity
generated by neurons
Two main techniques:
Probe the activity of one of a few neurons
Make recordings on the summated activity of
large clusters of neurons 61 62 Single-unit recordings
Thin electrode examines electrical changes caused
by activity in surrounding neurons; first developed
by Adrian in 1926.
Signal is amplified before being displayed.
the membrane While most work pre-1980s used
anesthetized animals, it is now more
common to use awake ones (anesthesia
effects, desire to study neural correlates of
particular behaviors) Edgar Adrian
(1889-1977) 63 Electroencephalography
Uses surface-based electrodes that sample electrical
activity over a larger area.
Electroencephalogram (EEG) recordings detect electrical
potentials on the skin surface that are due to the
spatially-averaged activity of large ensembles of neurons
beneath the skull.
Event-related potentials (ERP) tie the electrical response
to the presentation of a specific stimulus.
Good resolution for rapid time
changes, noninvasive, and
relatively quick and easy to perform
Because the brain is in a liquid
medium (that conducts electricity
well), very poor ability to resolve
where in space the brain signals
are coming from; may not be able
to detect signals from parts of brain
you are interested in studying (may
be “drowned out” by other brain
activity) Techniques for Studying Brain Function:
Functional Brain Imaging
Guided by the fact that there is an increase in
energy demand and supply, and blood flow to
brain areas that are active
Measures changes in blood flow, uptake of
labeled molecules associated with energy
metabolism, or changes in neurotransmitter
binding to different areas...
View Full Document
This document was uploaded on 02/16/2014.
- Winter '13