Transcript Tools for studying the nervous system

Tools for studying the nervous system
• 1929- Hans Berger
develops the
electroencephalograph
(EEG), which provided
insight into the living,
fully functioning brain.
Microelectrode Techniques
• Microelectrode recording techniques are used to study the
functions of single neurons
• Process:
• A microelectrode tip is placed directly inside of a neuron
• What is does:
• Studies changes in the electrical conditions of that neuron
• What it’s used for:
• Understanding the dynamics of action potentials, the effects of
drugs on neurons, and even process that occur in the neural
membrane.
Macroelectrode Techniques
• Macroelectrode techniques are used to detect the collective electrical
activity of millions of neurons
• Process:
• Large recording devices are placed directly on the surface of the scalp to
measure electrical activity of neurons in the underlying cortex
• What it does:
• Measures brain waves to provide an index of both size and rhythm of
neural activity
• What it’s used for:
• Provide an index of both size and rhythm of neural activity that have given
researchers valuable insights into sleep and dreaming
Types of brain waves
• Alpha waves
• Commonly found when you are relaxing with your eyes
closed
• Beta waves
• Higher-frequency waves that occur when you are
awake and still but your eyes are open
• Delta waves
• Low-frequency waves that occur during the deepest
sleep
EEG
EEG recording of one persons alpha brain waves
Red and violet colors indicate
greater alpha-wave activity
Structural Imaging
• Computerized axial tomography (CAT or CT) scanning
allows scientists to create 3D of a human brain without
performing surgery.
•
How it works: An X-ray photography unit rotates around the patient, moving from the top of the head to
the bottom. A computer then combines the images
• Magnetic Resonance Imaging (MRI) creates an even
better picture of the inner regions of the brain- its
ridges, folds, ad fissures
•
How it works: a patient’s head is placed in a magnetic field, and the brain is exposed to radio waves which
cause hydrogen atoms in the brain to release energy. The energy released by different structures in the
brain generates an image that appears on a computer screen.
MRI and CAT Scans
Functional Imaging methods
• Functional imaging methods strive to provide a picture of the brains
activity as it actually reacts to sensory stimuli such as pain, tones, and
words
• EEG Imaging: Measurements of the actual functioning of the brain are
made on a millisecond by millisecond basis.
• Use: useful in detecting abnormal cortical activity; like that observed
during an epileptic seizure
•
Magnetoencephalography (MEG) and Magnetic Source Imaging (MSI):
Take the process of EEG imaging a step further by eliminating the
distortion of the signals by measuring magnetic signals that are unaffected
by bone
• Use: Can identify the parts of the brain that do most of the work in
psychological process such as memory, language processing, and reading.
MEG Scan
Other methods of functional imaging
• Positron Emission Tomography (PET) scanning,
Radioactive PET, and Single Photon Emission Computed
Tomography (SPECT) use radioactive energy to map
brain activity.
• How they work:
• First: a radioactive substance is injected into the brain
• Next: Brain structures that are especially active
immediately after the injection absorb most of the
substance
• Then: When the substance starts to decay it releases
subatomic particles
The Peripheral Nervous system
• The Peripheral Nervous System
• Carries messages to and from the central
nervous system. It comprises two parts:
• - The Somatic Nervous System
• - The Autonomic Nervous Systems
•
The Somatic Nervous System
• The Somatic Nervous System is composed of the
sensory (afferent) neurons that carry messages to
the central nervous system and the motor (efferent)
neurons that carry messages from the central
nervous system to the skeletal muscles of the body.
The autonomic nervous system
• The Autonomic Nervous System carries messages between
the central nervous system and the internal organs. It is
broken into two parts: the sympathetic
and parasympathetic divisions.
•
•
Sympathetic:
Acts primarily to arouse the body; prepares the
body for quick action in an emergency
•
•
Parasympathetic:
Acts to relax and restore the body to normal
levels of arousal; calms and relaxes the body