Transcript Basic Neuroscience Series: Introduction and Series Overview

BASIC NEUROSCIENCE
SERIES:
INTRODUCTION AND SERIES OVERVIEW
Sindhu Ramchandren, MD, MS
AN OVERVIEW OF BASIC
NEUROSCIENCE
..Or,
How the knowledge of some esoteric
anatomic, cellular or signaling process
may help you treat a patient
What is Neuroscience?
• A scientific study of how the Nervous system (CNS and
PNS) carries out its function
• What are the Nervous System’s functions?
• The Nervous System directs an individual’s ‘normal interactions’
with external stimuli
• Thus, the Nervous System includes all thoughts, perceptions,
bodily actions, behaviors, and ultimately: Consciousness
• Philosophical debate:
• Dualism:
• Mind and Body are separate; “mind” is distinct from “brain”
• Rene Descartes (1596-1650): “soul” controlled muscles via the pineal gland
by hydraulic mechanisms
• Monism:
• Mind/brain is the nervous system
• Rapidly gained acceptance among neuroscientists, facilitated by discovering
electricity in the 18th century (Ben Franklin, Luigi Galvani)
Evolution of the brain
• The Human Brain has
evolved from the inside
out
• Lower regions like the
brainstem are generally
more ancient than higher
regions, such as the frontal
cortex.
• Basic survival functions
like breathing are
controlled in the lower
brainstem
• The large prefrontal cortex
in humans is a late
evolution
Localization based on:
• Symptoms: what the
patient experiences
• Signs: What the examiner
observes
• Helpful information:
 Timing (acute,
subacute, chronic)
 Progression (static,
step-wise regression,
relapsing-remitting;
progressive)
Basic Neuroscience can
help..
• Interpret the clinical
manifestations in
physiologic terms
• Suggest treatments
What is the brain made of?
• Cells - distinct, individual cells,
or networks of fused cells
(syncytium, reticulum)?
•
Debated by Camilo Golgi;
Santiago Ramón y Cajal,
etc.
• Methods:
1. Nissl and other traditional
stains
2. Golgi method
3. Fluorescence labelling
4. Electron microscopy
• Cell types: neurons, glia,
capillary endothelial cells
Building blocks
• Neurons: Responsible for information
•
•
•
•
•
transmission throughout the Nervous
system
Cell body: contains nucleus and other
biologic essentials to keep cell alive
Dendrites: fibers that project out of
the cell body, receiving info from other
neurons
Axon: transmits signals through the
neuron
Axon terminals: end of the axon; send
messages to a different neuron
Glial Cells: Support neurons by
disposing waste products, stabilizing
chemical environment, insulating
neurons
Signaling
• Communication within a
neuron is electrical
•
•
Axon- akin to the copper
wire; damage- see
dimunition of size
(amplitude)
Myelin (oligodendrocytes in
CNS; Schwann cells in
PNS)- akin to the insulation;
damage- see loss of speed
(conduction velocity)
• Communication between
neurons is chemical
•
Neurotransmitters
• Agonists: drugs that
increase the activity of
neurotransmitters
• Antagonists: drugs that
decrease the activity of
neurotransmitters
Peripheral Nervous System and disease states
A. Motor neuron:
•
A
B.
B
C.
C
D.
D
E
E.
MND
Nerve root:
• Radiculopathy
Peripheral nerve:
• Neuropathy
Neuromuscular junction:
• MG/ LEMS/ Botulism
Muscle
• Myopathy
Disease States
Cellular/genetic
• Cortical excitability: epilepsy
• Cellular dropout: Basal ganglia
degenerative disorders
• Neuromuscular junction blockade:
Myasthenia gravis, LEMS, Botulism
• Schwann Cell mutation: CharcotMarie-Tooth disease (CMT, or
inherited neuropathy)
Anatomic
• Anton’s syndrome (visual anasagnosia,
or cortical blindness): bilateral occipital
cortex lesion
• Alexia without Agraphia: (can write, but
can’t read; not even what they wrote):
Left occipital cortex lesion
• Gerstmann’s syndrome: Agraphia,
acalculia, finger agnosia, left-right
confusion: Left angular gyrus lesion
Heuristic: case-series based
• Patient HM
• intractable epilepsy (perhaps due to bike
accident at age 9)
• underwent surgery to remove
hippocampus at age 27
• left him profoundly amnesic
• Patient Phineas Gage
• Large iron rod destroyed his left frontal
lobe
• Profound changes in behavior and loss of
social cues
• The Man who mistook his wife for a hat
(Oliver Sacks)
• Prosopagnosia, visual agnosia
• The phantom within (Ramachandran and
Blakeslee)
• Phantom limb pain; mirror neurons and
neural plasticity
How principles of Basic Neuroscience help us
treat patients
• Brain scans- neurons require O2 and other nutrients to function
• PET scans use a dose of radioactive glucose, which moves to the
more-active areas of the brain
• fMRI detects active areas of the brain by enhancing those areas that
require more O2
• Neurophysiology:
• EMG/NCS: patchy slowing of conduction in several nerves can help
diagnose Chronic Inflammatory Demyelinating Polyneuropathy or its
variants
• EEG: If the differential of an obtunded patient is non-convulsive status
vs. metabolic encephalopathy, EEG showing Theta slowing with
triphasic waves can help support metabolic/hepatic coma
• Neurotransmitters:
• Allow us to manipulate disease states with appropriate uses of
agonists and antagonists.
Organization of Basic Neuroscience Series
Three “cores”
1.
Basic science ‘Anatomy’
• Embryology and cell type organization
• Cell types by specific sites (cerebral cortex, brain stem, spinal
cord, etc.)
2.
Physiology (normal)
• Cellular signaling
• Sensory integration (vision, balance, sensation, etc.)
3.
Physiology (disease)
• Specific disease states (not clinical care for them, but what went
wrong cellularly/mechanistically to result in the disease)
Last lecture of the year: “Physiology of Consciousness” By Dr.
George Mashour
Online “course”
• Online
Neuroscience
Course Link:
http://neuroscience.
uth.tmc.edu/toc.htm
Example: Retinal Circuit with Lateral Inhibition
Resulting in Edge Enhancement
From: http://neuroscience.uth.tmc.edu/toc.htm
Expectations
• What this course will emphasize:
• Overview of basic physiology, cell types, and signaling
• Overview of multiple ways the above can fail, leading to
disease states
• What it can’t do:
• Clinical overview- Dr. Callaghan’s Series will cover
those, BUT we have tried to ensure that most topics are
being presented by clinicians
• Pathology overview- We cannot do a whole overview of
CNS/PNS pathology and also do what the Department
has charged us with teaching you through this series,
BUT we do have a few lectures sprinkled in
Most importantly:
• These will be available at the
end of each upcoming lecture;
please provide your feedback
anonymously and I will review
the responses
• If there are themes that become
apparent in the feedback, I will
make sure that subsequent
lecturers are aware of what
works and what doesn’t, so they
can modify their talks (rather
than waiting for end-of-year
feedback only)
• This only works if you
ATTEND the lecture and fill
out the responses!
Discussion
• Beginning-of-year evaluation:
expectations
• Will repeat these at end-of-year, to make
sure we achieved the goals we set
• Any other thoughts or comments on
ensuring a good learning experience?