single cell recording
Summation of dendritic activity.
Scalp electrodes placed using the 10-20 International System
Other electrodes placed on face
(10-20 International System)
Beta activity (15-31 Hz)
Alpha activity (9-12 Hz)
Delta activity (1 to 4 Hz)
Theta (4-8 Hz)
What is an ERP?
Presentation of a repeated stimulus, sometimes for 1000 trials.
Summated postsynaptic activity from clusters of related neurons called generators.
Yields two primary measures: latency (time) and amplitude (how large the peaks are).
What is an ERP?
Early peaks (<100ms) are due to physical characteristics of stimulus (intensity, shape, etc).
Early peaks are used for diagnostic purposes (e.g., multiple sclerosis).
Later peaks (>100ms) are termed "cognitive peaks" and are related to thinking.
The latency (ms) and amplitude (Ķv) values for the later peaks are used for cognitive neuroscience.
0-100 ms transmission of sensory info to the cortex
100-300 ms N1-P2 selective attention
200-300ms N2 detection of physical deviance
300-800ms P3 memory of context updating
400-600ms N4 detection of semantic deviance
Clinical Psychology - emotional and behavioral problems.
Clinical Neuropsychology - integrity of the central nervous system
Cognitive capacity; strengths and weaknesses
progress during rehabilitation
Neuropsychological Test Battery
Halstead-Reitan (table 2.4, page 84)
Customized Neuropsychological Assessment
Flexible battery approach
Review of medical records (history, imaging, labs, etc)
- Impressions and recommendations
- Treatment plan
- Formal neuropsychological counseling
New learning and memory
Personality and mood
.Status Post Closed Head Injury, probably mild.
.R/O PTSD with depression.
.Severely impaired performance on tests of naming and fluency, verbal learning and memory that cannot be accounted for by mild closed head injury.
Computerized Axial Tomography
X-rays to provide information on density of brain structures.
CSF is less dense than brain tissue
blood is more dense than brain tissue
CT scans conít
Not horizontal, but oblique
Low resolution compared to other techniques
Magnetic Resonance Imaging
Relies on three magnetic fields.
Combines spatial information and signal information for 3D reconstruction.
Tuned to water or fat.
Spatial resolution superior.
Magnetic field soÖÖ.
Positron Emission Tomography (PET)
Useful for study of receptor distribution
Study of cerebral blood flow
Production of radioactive isotopes.
Functional Magnetic Resonance Imaging (fMRI)
Contrast agent (gadolinium)
Oxygenation of blood (blood rich in iron)
canít directly observe the function of the damaged portion of the brain.
underestimation of function due to compensation
Frontal opercular area
Dorsal parietal area
250 million fibers
Concrete words (real objects)
Simple grammatical comparisons
Canít control speech output
Canít process long grammatical comparisons
Canít do phonologic processing
Pointing to faces, objects, abstract forms.
Inject into carotid artery
Blood supply is unilateral
Paralysis on contralateral side
Left hemisphere is dominant for speech in 95% or right handers.
Divided Visual Field Technique
Divided Visual Field
RVF is directed to left visual cortex
LVF is directed to right visual cortex
Unilateral and bilateral presentation
Divided Visual Field conít
Divided Visual Field conít
RH (LVF) is more accurate and faster at detecting emotional faces.
These findings sometimes vary as a function of mood state, handedness, and gender.
LH (RVF) advantage for words
LH advantage for letters drawn on palm.
RH advantage for shape matching.
LH (right ear) advantage for words and other speech sounds.
RH (left ear) advantage for musical tones, animal noises, emotional speech
Left = evil, stubborn, defiant
LH dominance for speech in 70%
RH dominance in 15%
Bilateral in 15%
Speech may be spared after LH injury.
Spatial skills may be more impaired after LH injury.
Anatomical asymmetries are less marked.
Splenium - more "bulbous" in women.
Brain is smaller.
Differences in regional brain activation.
Differences in cognition during menstrual cycle.
Estrogen & Progesterone
high after ovulation
low during menstruation
Just after ovulation
better on some fine motor tasks
poorer on some spatial tasks such as mental rotation
Opposite pattern when female hormones are low, such as during menstruation.