Transcript Electrical Stimulation of the Brain

Neuroscience &
Biological
Foundations of
behavior
The Nervous System
Neurons
• Neurons are composed of:
– Cell body (soma): directs actions of the cell
– Dendrites: extensions that receive information
– Axon: extends from cell body, carries electrical
potential, sends a chemical message to adjacent
neurons via terminal buttons
The Action Potential
At rest, the inside of the neuron negative relative due to
a higher concentration of positively charged ions
outside the neuron.
When stimulated, sodium channels open and positively
charged sodium ions rush into the axon, depolarization
a small region within the axon.
The region of depolarization causes nearby sodium
channels to open. Just after the sodium channels
close, the potassium channels open wide, and
potassium exits the axon, repolarizing the tissue just
behind the action potential.
This process continues as a chain-reaction along the
axon. The influx of sodium depolarizes the axon, and
the outflow of potassium repolarizes the axon.
The sodium/potassium pump restores the resting
concentrations of sodium and potassium ions
http://intro.bio.umb.edu/111-112/112s99Lect/neuro_anims/a_p_anim1/WW3.htm
Myelinated Axons
Neurons are for Communicating
Synapse
Neurotransmitters
• Serotonin – affects mood, sleep, sensory
perception, and other functions, may play a role
in psychological disorders like depression
• Acetylcholine – involved in memory, muscle
action, sleep, emotions, those w/ Alzheimer’s
have lower levels
• Dopamine – affects movement, attention,
memory, learning, plays role in addiction
• Norepinephrine – affects learning, memory,
emotions, eating, alertness, etc.
• Epinephrine – emotions, memory storage…
Neurotransmitter
molecule
Receiving cell
membrane
Agonist mimics
neurotransmitter
Receptor site on
receiving neuron
Antagonist
blocks
neurotransmitter
Nicotine is an
acetylcholine agonist
Curare is an acetylcholine
antagonist
The Nervous System
CNS =
Central Nervous System
PNS =
Peripheral Nervous System
Peripheral Nervous System
PNS includes all nerves outside the brain and
spinal cord
– Broken down into somatic and autonomic
nervous systems…
• Somatic NS carries sensory messages to
brain and motor commands to the muscles
Somatic Nervous System
Peripheral Nervous System
• Autonomic N.S. regulates automatic
body functions (heart rate, breathing)
• Sympathetic: “Fight or Flight”
• Parasympathetic: Active during digestion
Autonomic Nervous System
The Spinal Cord
Midline Brain View
Lower Level Brain Structuresoldest part of the brain
3 major Brain
Stem
Structures:
1. Pons
2. Medulla
3. Reticular
Formation
Midline Brain View
Corpus Callosum –
connects 2 brain
hemispheres
Thalamus
Sensory relay
area
HypoThalamus
4 F’s…
Feeding,
Fleeing,
Fighting
& Mating
CereBellum Smoothes
movements
4 lobes of the cerebral cortex –
Frontal, Parietal, Occipital, Temporal (F-POT)
Frontal Lobes: Motor Control, Speech Production, Higher
Functions
Broca’s Area
Phineas Gage… 1823 - 1861
4 lobes of the cerebral cortex –
Frontal, Parietal, Occipital, Temporal (F-POT)
Occipital
Lobes
Summary of
Hemispheric
Specializations“lateralization”
Studying the Brain
• Lesion studies: a brain region is
destroyed and behavior is
observed
–Lesions of hypothalamus in animals --> overeating
–Strokes interrupt blood flow in brain --> damage brain
Studying the Brain
• Electrical Recording:
overall brain wave
activity monitored by
electroencephalograph
(EEG)
• Electrical Stimulation of
the Brain (ESB)
Studying the Brain
• Imaging techniques
allow the living brain
to be studied for its
activity during
behavior
– CT scans (computed
tomography) used to
detect brain structure
abnormalities in people
w/ mental illness
meningitis
left temporal
tumor
Studying the Brain
–PET scans use radioactive glucose
to assess brain activity
Control
Ecstasy User
Studying the Brain
MRI Scan of Tumor in
Speech Center
–MRI scans
generate 3D
views of the
human brain
• fMRI – faster
version of MRI
MRI for Face Recognition
in Normal Volunteer >