Transcript What's a Brain? Part 1 - UCSD Cognitive Science

COGNITIVE
SCIENCE
17
What’s A
Brain?
Part 1
Jaime A. Pineda, Ph.D.
Meshberger, JAMA 264:1837-1841
The Fundamental Circularity of
Being
“The world is inseparable from the subject, but from a
subject which is nothing but a projection of the world,
and the subject is inseparable from the world, but from
a world which the subject itself projects.”
Merleau-Ponty (1906-1961)
Mind-Body Question
• Dualism
– Belief in the dual
nature of reality
– Mind and body are
separate
– Body is made of
ordinary matter
– Mind is not
• Monism
– Belief that everything
in the universe consists
of matter and energy
– Mind is a phenomenon
produced by the
workings of the
nervous system
The goal of Cognitive Neuroscience is to provide and
explain the mapping between
brain and mind
Or put another way, between
structure and function
Is there an identity such that brain=mind?
Is it more of a correspondence?
Just what is the relationship?
BODY-MIND RELATIONSHIP
(STRUCTURE-FUNCTION)
• BODY/BRAIN
• MIND
Memory
Attention
Language
Planning
Creativity
Awareness
Consciousness
Classical physics
BODY-MIND RELATIONSHIP
(STRUCTURE-FUNCTION)
• BODY/BRAIN
• MIND
Memory
Attention
Language
Planning
Creativity
Awareness
Consciousness
Self-directed neural plasticity?
Quantum physics and the causal efficacy of thought?
Is Reality a “Construction”?
Stimulus
Bottom-up processing
Selection
Interpretation
Top-down processing
Rene Descartes
(1596-1650)
De Homine – 1662
Mechanistic view of brain
Pineal gland – gateway to soul
“…ingenuity and originality
were unfortunately based on
pure speculation and incorrect
anatomical observations.”
“I think therefore I am”
Luigi Galvani
(1737-1798)
Professor of Obstetrics
Moves frog leg with static electricity
Detects electricity in the nerves of
frogs
Bell –Magendi Law 1811
Paul Broca
(1824-1880)
Anthropologist and anatomist
Paris educated MD pathologist
“Tan” aphasic patient died in
April 1861
“Nous parlons avez l’hemisphere
gauche”
(We speak with the left hemisphere)
Franz Joseph Gall
(1758-1828)
Analysis of the shapes and
lumps of the skull would
reveal a person’s personality
and intellect.
Phrenology
Modern Phrenology
Unilateral Neglect
- lesions to right parietal
cortex
- failure to notice things
on the left side
- failure to remember
things on the left side
Split Brain
Neurons
• Functional units of
communication
• 100 billion + a few million
• Independent units (Neuron
Doctrine)
• Bioelectrically driven
(Functional polarity)
• Categorized in terms of
Function (sensory, motor);
Location (cortical, spinal);
NT (cholinergic);
Shape (pyramidal, stellate)
dendrites
Bipolar
cells
axon
terminal
bouton
Variety of Multipolar Neurons
Differ in terms of:
•
•
•
•
•
genes expressed
chemicals
shape
arborization
connectivity patterns…
Structure  function
104 connections per neuron
1014 total interconnections
(one hundred trillion)
Dendritic Spines
Myelination
• Insulates axon
• Speeds up conduction
without increasing
diameter of axon
• Saves energy
Nodes of Ranvier
Neuroglial Cells
• Physical and metabolic support
• 90% of cells in brain
• Four types
–
–
–
–
Astrocytes (maintenance/support)
Oligodendrocytes (myelin)
Ependymal (line ventricles)
Microglia (macrophages)
Einstein’s Brain
Greater number of
neuroglia
Larger inferior parietal
cortex