Neural Systems Overview

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Neural Systems Overview
Lectures MWF FLTC 214 Website
http//vestibular.wustl.edu/syscourse Background
readings for each lecture listed on website.
Supplemental material and lecture ppt files
will be posted on website also. Please read
background before lecture. It will keep you
sane! Ask questions! You are here to
learn Labs/Demos Wed, 1-4 PM, FLTC 301 AB
(except when noted as to different location)
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Grading
Quizzes (50) 12 short quizzes given on Mondays
before lecture Include questions from lectures
and labs Let me know about conflicts
ASAP Take-home midterm exam (25) Two weeks to
complete (open book, but do your own work) Final
(25) Comprehensive at end of course Extra
credit assignments (equal to 1 quiz score)
1or 2 given during course Recommended texts
Neuroscience, Purves et al, 4th ed, 2008
(lectures) The Brain Atlas, Woolsey
et al., 3rd ed, 2008 (lab) (available in WU Med
Bookstore and Library reserve)
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You should know
This is a Neuroscience course Knowledge of
elements and structures (new nomenclature) Low-le
vel physiology as well as high-level
cognition Some psychophysics, computation,
behavior You all have different
backgrounds Some things will be easier, some
harder Learn from each other Be open minded,
ask LOTS of questions
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What is Systems Neuroscience?
Neural Systems focus on how simple and complex
functions arise physiological systems interact
with environment perception is a biological
process that interprets reality, arises from
structure, experience, and bias plasticity,
learning, cognition   Four general neural
system themes will be emphasized Architecture
produces function Sensory systems Motor
systems Cognitive processing, integration Is
this inclusive? No, but an eclectic overview for
you to gain insight into specific issues of
brain function, perception, decision, behavior,
and awareness
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Levels of Analysis
Systems neuroscience
Cellular neuroscience
After Churchland Sejnowski 1992
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Elements of neural systems
The primary element of information processing
neurons

• Camillo Golgi championed the reticularist view
• that nerve cells fused into a
  continuous network
• of cytoplasmic continuity
• Santiago Ramón y Cajal proposed the Neuron
  Doctrine
• that states each neuron is an
  individual entity

Cajal
Golgi
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Understanding neural systems
Vision
Olfaction
Somatosensory
Cortex
Doctrine of specific nerve energies
In 1826, Johannes Müller proposed that each nerve
gives rise to a single modality sensation.
A view supported later by Cajals work, but not
the whole story. Today, we commonly refer
to this principle as the labeled line code.
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Simple vertebrate neural reflex systems
Patellar reflex
Principally involves only four neurons and is
completely contained in local spinal systems.
No cortical involvement or cognitive perception.
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Vestibulo-ocular response to head motion
The short latency simple VOR path consists of 3
neurons 1) afferent fiber 2) central VNC
neuron 3) eye muscle motor neuron With a left
head rotation 1) Left afferents excited, right
inhibited 2) VNC cells on left excited 3) VNC
projects excitatory input to contralateral
(right) abducens neurons 4) Abducens motor
neurons excite right lateral rectus 5) Abducens
interneurons project back across to excite left
oculomotor neurons and left medial rectus 6)
Opposite action inhibitory path from right canal
and circuit More sophisticated Retinal error
signal from cerebellum produces motor learning
through feedback into system
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Complex neural system in sound localization
NM nucleus magnocellularis NA n.
angularis SON superior olivary n. NL n.
laminaris
Interaural timing differences (ITD) used for
detecting sound location along the azimuth.
Cells in the NL respond only when the timing
(phase) of sound waves reaching the two
ears is temporally correlated
Nucleus Laminaris
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Simple motor behaviors rely on complex neural
systems
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Course Goals What should a systems
neuroscientist know?

• Factual Knowledge
• The structure neuroanatomy and connectivity
• What the structural elements can do
  neurophysiology
• How specific systems are organized and how they
  work
• What tools are available methods
• Conceptual Knowledge
• Architecture
• Neural Encoding
• Neural Decoding
• Neural Representations
• Population activity
• Maps
• Behavior

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Methods and Tools

• Anatomical
• Neuron morphology
• Pathways
• Stuctures and nuclei
• MRI
• Physiological (Invasive)
• Single-unit recording
• Multiple-unit population recordings
• Optical imaging
• Electrical microstimulation
• Reversible inactivation
• Viral expression and imaging

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Methods and Tools (cont.)

• Physiological (Non-Invasive)
• EEG Brain Map
• fMRI
• PET
• Behavioral
• Psychophysics
• Motor control
• Learning
• Information processing/perception
• Modeling and Engineering Approaches
• Systems analyses
• Bayesian processing
• Computational neuroscience

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Comparative approaches
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Methods Spatial and Temporal Resolution
PET
fMRI
lesions
microlesions
light microscopy