Transcript Since Last Discussion:

Since Last Discussion:
XII: Experience and Critical Periods (aka,
Plastics)
XIII: Brain Diseases I
XIV: Brain Diseases II
XV: Genetics and Human Brains: Clues from
Abnormalities
XVI: Reflections on Higher Brain Functions
Lecture XII: Plasticity
Neuromorphological
Early
Functional
Molding
Adult
Tweeking
On the Cellular Level (Hebb Rule)
Neuromorphological Plasticity
Organization
guided by input
Whisker and
Neuronal
Connections (9)
Human: Visual
Cortex (11)
Periphery input to
cortex
Experiment: Label EyeSpecific Neurons (12)
No Genetic
Predisposition
Labeled axons from visual
thalamus to visual cortex in
monkeys of different ages
October 11, 2010
Axons related to left eye are red
and those related to right eye are
blue
XII. Experience & Critical Periods (aka
Plastics)
5
Neuromorphological Plasticity
Organization
guided by input
Whisker and
Neuronal
Connections (9)
Human: Visual
Cortex (11)
Periphery input to
cortex
Experiment: Label EyeSpecific Neurons (12)
Wide Branching to
Delineated (13)
No Genetic
Predisposition
Don’t use it, lose it.
(14,15)
Functional Plasticity
Ends with Puberty
Reinforcing Good
Connections
Early vs Late Bilinguals
(21,22,23,24)
Language Production
“Early” bilingual subject -
“Late” bilingual subject -
Broca’s Area (Brodmann’s 44+)
Broca’s Area (Brodmann’s 44+)
October 11, 2010
XII. Experience & Critical Periods (aka
Plastics)
8
Functional Plasticity
Ends with Puberty
Reinforcing Good
Connections
Lose unused neurons
(25)
Early vs Late Bilinguals
(21,22,23,24)
Adult Plasticity
Reinforcement
through
experience;
adjustments
Demo
Quickly learned and
lost (half-life)
Hebb Rule
Persistent firing of a cell by a different neuron
results in metabolic or growth process
change (37).
1. Increase post-synaptic sensitivity (38)
2. Create new synapses (39)
October 11, 2010
XII. Experience & Critical Periods (aka
Plastics)
12
October 11, 2010
XII. Experience & Critical Periods (aka
Plastics)
13
Lecture XII: Brain Disease: Parkinson’s
• Phenotype: Characterized by an inability to initiate movement (walking)
or terminate movement, tremors at rest, rigidity and minimal facial
expressions.
• Pathophysiology: Loss of Substantia nigra results in lost dopaminergic
neurons
• Loss of thalamic output from basal ganglia
• Reduced excitation of motor neurons in the superior collicus and cortex
THE BRAIN ATLAS, 3rd ed p 74
Substantia Nigra
October 13, 2010
Lecture XIII. Brain Diseases - I.
15
THE BRAIN ATLAS, 3rd ed p 139
Substantia Nigra
October 13, 2010
Lecture XIII. Brain Diseases - I.
16
Thalamus
Globus Pallidus
Caudate Nucleus & Putamen
Decreased
Excitation of
Cortex
Substantia Nigra
Subthalamic Nucleus
Thalamus
Caudate Nucleus & Putame
Globus Pallidus
Subthalamic Nucleus
Substantia Nigra
Increased
Excitation