Transcript ppt - IISER Pune

Organization of the nervous system 2
Raghav Rajan
Bio 334 – Neurobiology I
August 22nd 2013
19th August 2013
Bio 334 - Neurobiology I - Organization of the nervous system
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Orienting within the brain – absolute axes and relative
axes
SUPERIOR
(above)
●
●
ANTERIOR
(in front)
Anterior/Posterior,
Superior/Inferior –
absolute axis system
Rostral/Caudal,
Dorsal/Lateral – relative
to the long axis of the
brain or spinal cord
POSTERIOR
(behind)
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INFERIOR
(below)
http://www.rci.rutgers.edu/~uzwiak/AnatPhys/APFallLect19.html
Bio 334 - Neurobiology I - Organization of the nervous system
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Medial – lateral axes
LATERAL
(away
from the
midline)
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MEDIAL
(near the
midline)
LATERAL
(away
from the
midline)
Bio 334 - Neurobiology I - Organization of the nervous system
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Ipsilateral and contralateral – things on the same side
or the opposite side
IPSILATERAL
(same side)
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CONTRALATERAL
(opposite side)
Bio 334 - Neurobiology I - Organization of the nervous system
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Planes of brain sections
Kandel, Schwartz and Jessell, Principles of Neural Science
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Bio 334 - Neurobiology I - Organization of the nervous system
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Divisions of the nervous system
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Bio 334 - Neurobiology I - Organization of the nervous system
http://serendip.brynmawr.edu/exchange/brains/structures
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Basal ganglia are a set of nuclei within the brain
●
●
Clearly
distinguishable
cluster of neurons
usually deep in the
brain
Shows up as a some
gray matter often
surrounded by
white matter
Kandel, Schwartz and Jessell, Principles of Neural Science
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Bio 334 - Neurobiology I - Organization of the nervous system
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Basal ganglia consist of 4 nuclei
●
Striatum
●
Pallidum
●
●
Substantia
nigra
Subthalamic
nucleus
Kandel, Schwartz and Jessell, Principles of Neural Science
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Bio 334 - Neurobiology I - Organization of the nervous system
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The basal ganglia form loops with the cortex and
thalamus
●
●
Cortex - Basal gangliathalamus – cortex
loops are important in
the initiation and
selection of
movements
Normal function
disrupted in many
diseases – Parkinson's
disease, Huntington's
disease
Multiple parallel loops
Kandel, Schwartz and Jessell, Principles of Neural Science
involved in other
functions too
●
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Bio 334 - Neurobiology I - Organization of the nervous system
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They are involved in movement selection and
movement initiation
●
●
●
●
Two pathways:
Direct pathway – initiates
movements
Indirect pathway – suppresses
movements
Recent optogenetic experiments
show this very nicely
Supplementary videos 2 and 3
from
http://www.nature.com/nature
/journal/v466/n7306/full/natur
Yin and Knowlton, The role of the basal ganglia in habit formation. Nature Reviews Neuroscience (2006)
http://www.nature.com/nrn/journal/v7/n6/fig_tab/nrn1919_F1.html
e09159.html#supplementary19th August 2013
Bio 334 - Neurobiology I - Organization of the nervous system
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information
–
Songbirds have served as a good model system for
understanding the function of these loops
●
●
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Evolutionarily conserved –
neuronal morphology,
molecular markers, activity
patterns, connections
Specialized portion of this loop
appears to be involved only in
song learning
Bio 334 - Neurobiology I - Organization of the nervous system
http://www.nbb.cornell.edu/goldberg/
Doupe AJ et al. Songbirds could teach basal ganglia research a new song. Trends in Neurosciences 2005
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This loop is important for learning and is involved in
generating variability required for learning
●
Learning of complex
movement sequences
requires three steps
–
Exploration using
variability
–
A mechanism to decide
“good” and “bad”
outcomes
–
Selectively re-inforce
“good” outcomes
Doupe AJ et al. Songbirds could teach basal ganglia
research a new song. Trends in Neurosciences 2005
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Basal ganglia loops are thought to form parallel
circuits that have a number of other functions too
●
Parallel loops with high
degree of organization
Kandel, Schwartz and Jessell, Principles of Neural Science
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Bio 334 - Neurobiology I - Organization of the nervous system
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Hippocampus and associated structures are involved in
learning and memory
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
H.M. (Henry Molaison) revolutionized our
understanding of function of hippocampus
●
Surgery when he was 27
●
Died at the age of 82
●
●
●
●
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Could not form new
memories
Only some types of
memories were affected
Could remember most
things from before
surgery
CAVEAT: Lesions
encompass larger area
than just hippocampus
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http://en.wikipedia.org/wiki/Henry_Molaison
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Diencephalon gives rise to thalamus and hypothalamus
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
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Bio 334 - Neurobiology I - Organization of the nervous system
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Thalamus is the “gateway” to the cortex
●
●
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All sensory (except olfactory) are
relayed to the cortex through the
thalamus
Thalamo-cortico-thalamic loops
are believed to be important for
consciousness
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Midbrain gives rise to tectum and tegmentum
●
●
●
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Tectum consists of
superior and inferior
colliculus
Superior Colliculus
gets information
from eye and
controls eye
movements
Inferior colliculus
gets information
from the ears
Bio 334 - Neurobiology I - Organization of the nervous system
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Midbrain gives rise to tectum and tegmentum
●
●
●
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Tegmentum consists
of red nucleus and
substantia nigra
Both are involved in
controlling voluntary
movement
Corticospinal tract
passes through the
midbrain
Bio 334 - Neurobiology I - Organization of the nervous system
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Rostral hindbrain gives rise to cerebellum and pons
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Caudal hindbrain gives rise to medulla
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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Cerebellum is again involved in modifying movements
●
●
●
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Gets detailed motor
information through the
pons about the
commands that have
been sent out from
cerebral cortex
Receives sensory
information from the
spinal cord about body
position, etc
Can then compare and
adjust movements
Lesions result in
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●
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
Pons – a “switchboard” for the cerebellum
●
●
Carries information from cerebral cortex to cerebellum
Also controls a number of vital functions like breathing,
sleep, bladder control, swallowing, etc.
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Bio 334 - Neurobiology I - Organization of the nervous system
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007)
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Medulla ●
Has motor neurons that control the tongue
●
Receives a lot of sensory information from various senses
●
A number of other autonomous functions
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Bio 334 - Neurobiology I - Organization of the nervous system
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007)
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