Recording an Electroencephalograph

Recording an Electroencephalograph

The following directions need to be confirmed and cleaned up, but should allow tracings to be performed using the Biopac Student Lab software and a computer.  Pictures should follow as soon as we perform the experiment in the lab (around 3 February 2005):

RECORDING AN EEG Using BioPac Student Lab, Version 3.6.7

Using BioPac Student Lab, Version 3.6.7
1)    Turn on computer, login: USERBL (a faculty member will log in for you)
2)    Plug electrode lead into Channel 1.
2)    Open software: BioPac MP30 Student software
3)    Choose Lesson: click on LO3- EEG-1
4)    Create your file: Type your file name (LASTNAME_X) where X = first name initial, ENTER
5)    Connect electrodes: (They MUST have excellent contact with skin for success.)
a)    If skin is moist or oily, wipe skin at electrode placement sites with 95% EtOH, dry well.
b)    Part the hair so you see the scalp and apply electrodes over the R and L edges of the occipital bone, about 3 inches apart.  Press the third electrode on the inside R wrist.
c)    Clip lead harness securely to belt or clothing, attach leads to electrodes:
i)    red lead to left occipital electrode
ii)   white to right occipital electrode.  Place snug fitting cap to hold in place (panty hose?)
iii)  black lead to inside of wrist.  (If necessary, tape down with masking tape.)
6)   CALIBRATE: Darken the room, lie the subject down and relax, breathing regularly.  Click CALIBRATE.  Double check electrode position, click OK.  Look for even, flat line, no spikes.  If it contains erratic “static,” recheck to secure electrode placement (more gel?) and repeat calibration.
7)    After calibration has been successfully completed, proceed to next step.
8)    With complete silence of observers, have subject lie completely still with no facial movements.
9)    RECORD: With subject’s eyes open, click on RECORD.  You should see high frequency (15-60 Hz) low amplitude (5-10 mV) beta waves, typical of the alert brain.
10)    After 15 seconds with eyes open, have subject close eyes closed for 30 QUIET seconds (RELAXED…).  You should see occasional low frequency (8-10 Hz) high amplitude (50 mV) alpha waves (if the subject is truly relaxed).
11)    After 30 seconds in deep meditation, have subject open eyes for 15 seconds.
12)    After 60 seconds total, click button STOP.
13)    If the tracing is satisfactory (look especially for alpha waves when eyes closed), click on DONE.
14)    It asks if you want to stop recording, click YES.
15)    A new menu appears, highlight ANALYZE CURRENT DATA FILE to select, click OK.
16)    Click FILE, select DISPLAY PREFERENCE, highlight SHOW GRIDS, click OK.
17)    Click arrow button in lower right side of screen
18)    Left click the space below the graph (next to “seconds”).
19)    A menu appears, enter time in the seconds you wish to print for upper scale range, set time division lines at 2 seconds, click OK.
20)    Left click voltage space to the right of the graph, set voltage range -50 to +50 mvolts, set voltage division lines at 10 mV, click OK.
21)    Click FILE, select PRINT.
22)    Select PRINT GRAPH, click OK.
23)    The Print Options menu appears.  Enter “4″ in the plots per page space.
24)    Click on PRINT.
25)    Collect printed tracing from the Lab printer.   Label when eyes were open or closed, and indicate beta and alpha EEG waves.  At the print conditions described in #16-20, 1 interval equals 2 seconds.  Mark the one second intervals below the graph (ignore the printed numbers, they are erroneous…)  Indicate how many hertz (cycles per second).  Cut in half and mount in notebook.

PREVIOUS EEG RECORDING EQUIPMENT:
The following are instructions for recording brain waves usng relatively primative equipment we have used for previous years.  Even with the age of the equipment, good tracing can be recorded with proper attention to the idiosyncrasies of the equipment and an understanding of the principles involved.

Equipment and supplies (using Thorton Electronics instruments): strip chart recorder (type-462)
isolated preamp (type-410)
EEG amplifier (type-418)
Bio-amplifier/supply (type-400)
BNC cable, 24 inch
lead wire assembly: +, -, and ground
three electrode plates
two rubber straps, 16 and 30 inches
electrode cream (Medi-Trace EKG sol)

  1. Assemble and pre-set apparatus:

EEG_amplifiers_P2041945md

Connect amplifier complex by pushing together:

EEG_apparatus_P2041948md
EEG Apparatus
  1. a) preamplifier
  2. b) EEG amplifier
  3. c) Bio-amp/supply

Connect BNC cable from EEG amplifier output to Strip chart recorder signal input jack.
Turn off the power in both strip chart recorder and bio-amp/supply, then plug each into a 110 volt line.
Pre-set the initial settings as follows:

Strip chart settings: During Setup When running a tracing
Power Switch: OFF ON
vertical amplifier:* 10 mV/cm
Coupling: GND AC
Chart Drive: 5 mm/SEC 25 mm/SEC
Drive Power Switch: OFF ON
Pen position & heat: both at mid-settings adjust for darkness and position
Bio-amplifier/supply settings:
Power Switch: OFF
Bandwidth:* 25 Hz
Coupling:* AC
  1. Plug lead wires into preamp: Check that three lead wires are not tangled, then plug into isolated preamp receptacle labeled “electrodes”. Handle with care (do not pull).

wrist_electrodes_P2041937md

  1. Attach ground electrode to wrist: Attach an electrode plate to the end of the 15 inch strap, apply electrolyte cream, and strap snugly to the inside of a wrist, with the thumb screw toward the hand.

electrodes_occipital_P2041935md

  1. Attach two electrodes to scalp: Attach 2 electrode plates to the 30 in. strap, the first at the end, and the second 4-5 inches from the first. Place a drop of electrolyte cream the size of a pea on each. With assistance, part hair on lateral occipital portions of subject’s head, 2.5 inches from midline. With thumb screw inferior, press the first electrode so cream smushes into scalp. Hold in place. Part hair on other side of midline, slightly stretching rubber band and smush second electrode into scalp (also with thumb screw inferior). Hold the second in place also. Have assistant gently stretch rubber band around front of head, and attach to first electrode. Make sure it is not too tight.

electrodes_occipital_P2041936md

  1. Connect wires to electrodes: Attach the ground (G) wire to the ankle electrode, tighten with thumb screw. Repeat with the “+” and “-” wires on the R and L electrodes on scalp. The wire fittings are fragile, handle with care (DO NOT PULL THE WIRES).

recorder_P2041960md

  1. Adjust settings on machine: With subject in a relaxed, comfortable position, change settings to those in the table above: When you switch the coupling on the recorder to AC, the needle should now be moving up and down. (If no needle movement, check connections and wiggle switches.)
  2. a) Adjust moving pen position to middle of paper.
  3. b) Turn on chart drive.
  4. c) Adjust pen heat so tracing is a thin black line.

 

  1. Record beta waves of alert subject: When satisfied with preparations and the quality of the tracings at 5 mm/sec, switch chart speed to 25 mm/sec. These high frequency (15-60 Hz) low amplitude (5-10 mV) waves are beta waves, typical of the alert brain. Switch off chart drive. (This image has beta at the left, alpha at the right)
beta_to_alpha_P2041938md
Tracing showing beta and alpha waves
  1. Record alpha waves of meditating subject: Have subject lie down in dark, close eyes, breath slowly and deeply to relax for several minutes. Set chart drive at 5 mm/sec. Maintain silence. Run for about a minute. Notice the periodic episodes of alpha waves. Alpha waves are low frequency (8-10 Hz) high amplitude (50 mV) waves. When they appear, switch the chart speed to 25 mm/sec. After a minute, without turning off the machine, have subject open eyes and converse, but not move around, press event button to indicate this change in parameters. The EEG pattern should return to the beta pattern.

alpha_P2041939md

  1. Illustrate apparatus, label all features used with appropriate numbers. Cut out examples of alpha and beta waves to mount in your notebook (using scotch tape at the edges, not contact paper). Label and discuss characteristics and significance of each type brain wave recorded.

Very rough board notes to introduce brain waves, 2003 (as temporary service to students). Board 1, board 2.

Advertisements

Histological Features of the Spinal Cord

Histological Features of the Spinal Cord

Examine the cross sections of the spinal cord with the 4x objective first. Locate all major regions as listed below. At higher power, note cell structure of central canal, posterior and anterior gray horns, and funiculi. Then illustrate first at lowest power and label the following:

Slide 4: Spinal Cord cross section and longitudinal sections, H-Eosin (H 1537)
Make four illustrations:

Spinal Cord cross section
(40x): (MF 4th : pages 99, 101)

anterior median fissure
pia mater
arachnoid meninx
dura mater (if present)
posterior median sulcus
posterior gray horn
posterior funiculus
lateral gray horn
lateral funiculus
central canal
ependymal cells
white commissure
grey commissure
anterior gray horn
filaments of ventral root
anterior funiculus
Here is a labeled view of the spinal cord.

Central_Canal_PC271502md
central canal, 400x

Central Canal, 400x
a: Central Canal (400x)
ependymal cells
cilia
grey commissure
lumen
Here is a labeled view of the central canal.
anterior_horn_cell_PC271503

Anterior Horn Cell, 400x
b: Anterior horn cell (400x)
clear hillock
nucleus
nucleolus
Nissl bodies
Here is a labeled view of anterior horn cells.

myelinated_fibers_PC271506md
myelinated fibers, 400x
c: myelinated fibers (See MF 4 th:93-95) (400x)
(cross section at posterior funiculus)
multiple cross sections of fibers
myelin sheath
axon

Dorsal_Root_Galglion_PC271483md

Dorsal Root Ganglioin, 40x
Slide 5: Spinal Cord with Dorsal Root Ganglion cross section, Ag stain (H 1560)
(MF 4 th: page 97) Single large illustration showing all of the following (40x):
Here is a labeled view of the spinal cord with dorsal root ganglion.
spinal_cord_PC271507md

spinal cord general features:
posterior gray horn
anterior gray horn
anterior median fissure
posterior median sulcus
dorsal root ganglion
dorsal root ganglion, 100x

ganglion_PC271508md

dorsal root ganglion features:
ganglion cells
nerve fibers
epineurium (capsule)
dorsal root
if present:
ventral root
spinal nerve
Here is a labeled view of the dorsal root ganglion..

ventral_root_PC271510md
This detail shows the ventral root where it is formed from fibers from the anterior gray horn

Additional images of the spinal cord

Introduction to Nervous Tissue Histology

Introduction to Nervous Tissue Histology

Examine the following slides and identify the listed features. Survey each slide for the best typical field which shows the listed features, and illustrate it at the indicated power, labeling these features. At home, fill in the significance of each feature in a sentence or two. Follow protocol Notebook Illustrations. (MF 9 th= Eroschenko’s 9th Ed)

Slide 1: Spinalmotor nervecell, ox, hematoxylin-eosin stain (H 1660)
(MF 9 th , page 89) at 400x:
scan with 4x objective, find a neuron which best shows the following, draw at 400x:

Neuron: the functional unit of nervous system
Identify the following features:
nucleus houses genetic material
nucleolus synthesizes ribosomal RNA, assembles ribosomes. Prominent in neurons.
Nissl bodies rough endoplasmic reticulum (synthesizes protein). Prominent in cytoplasm.
perikaryon also known as cell body, equals the area “around the nucleus”
axon hillock often tapered, gives rise to the axon, pale or clear due to lack of Nissl bodies
dendrites darker stained projection, carries impulses toward cell body. Can be multiple.
axon clearer projection, carries impulses away from cell body
astrocytes most common neuroglial cells, support, nourish neurons
microglia cells with large nuclei dispersed among astrocytes (scarce), phagocytic

Here is an older version of a labeled version of the 400x image of a neuron.


Slide 6: Motor nerve endings with end plates, snake, AuCl 2 stain (H 1685)
Motor end plates, known also as neuromuscular junctions
(MF 9 th , page 81) at 400x:

Identify the following features:
skeletal muscle also known as striated muscle, bands of sarcomeres visible
nerve bundle axons bound together by Schwann cells (not visible)
axon delivers impulses to the motor end plate
motor end plate a cluster of synaptic knobs attached to muscle fibers
synaptic knobs (or boutons) release acetylcholine, the neuromuscular neurotransmitter

Here is a labeled version of 400x view of a motor end plate.
Here is an older version of a labeled of 400x view of a motor end plate.

cut here ———————————————–

FOR DAY OF PERIPHERAL NERVES IN THE CAT

Slide 10: Vater-Pacini corpuscles, pancreas, H-eosin (H 1688)
Pacinian corpuscles, specialized nerve ending which detects pressure and vibration in an organ.
(MF 9 th: page 229 and 147) at 100x:
Pacinian corpuscle:
connective tissue capsule
central cavity with numerous lamellae (with flattened nuclei) and naked dendrite
Pancreatic acini