ppt - IISER Pune

Organization of the nervous system 3

Raghav Rajan Bio 334 – Neurobiology I August 26th 2013 26th August 2013

Bio 334 - Neurobiology I - Organization of the nervous system 3

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Spinal cord ●

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Dorsal roots carry sensory information

Ventral roots carry motor information Controls voluntary and reflexive movements Receives sensory input from skin, joints, muscles Paralysis inferior to location of damage

Bio 334 - Neurobiology I - Organization of the nervous system 3

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Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7

PNS ●

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Somatic PNS – related to voluntary control

Visceral PNS – involuntary – innervates internal organs, glands, blood vessels, etc.

Bio 334 - Neurobiology I - Organization of the nervous system 3

http://en.wikipedia.org/wiki/Peripheral_nervous_system

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General functions of nervous system ●

To find food

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To avoid being eaten

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To reproduce

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Bio 334 - Neurobiology I - Organization of the nervous system 3

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Evolution of complex nervous systems ●

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Evolution selects for adaptations that promote the ability to pass on genetic material

Works on what is already there Needs some amount of redundancy to tinker and make changes

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Bio 334 - Neurobiology I - Organization of the nervous system 3

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General principles of organization of nervous system ●

Organization of sensory and motor areas dependent on environment, relative importance of different sense organs, motor capabilities

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Based on anatomy, we can delineate functional systems

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Functional systems are organized into maps

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Hierarchy of functional systems?

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Functional systems on one side of the brain (cerebral cortex) get information and control the contralateral side of the body Kandel, Schwartz and Jessell, Principles of Neural Science

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Bio 334 - Neurobiology I - Organization of the nervous system 3

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Sensory and motor cortical representations not proportional to external size

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http://www.autismindex.com/Therapies/Therapy_Key_Word_Site_Map/sensory/motor_sensory_homunculus.html Bio 334 - Neurobiology I - Organization of the nervous system 3

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Important sensory organs are better represented in the cortex and sub-cortical structures

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http://www.pnas.org/content/109/Supplement_1/10647.long

Bio 334 - Neurobiology I - Organization of the nervous system 3

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Functional systems – like the visual system – two streams of processing ●

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Dorsal pathway - “vision for action” - where

Ventral pathway - “vision for perception” - what Now, considerable evidence for interaction between both pathways

http://www.waece.org/cd_morelia2006/ponencias/stoodley.htm

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Bio 334 - Neurobiology I - Organization of the nervous system 3

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Maps – sensory, motor, etc.

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http://uc.exteenblog.com/highwind/images/Know/brain_homunculus1.jpghttp://w ww.wiringthebrain.com/2010_12_01_archive.html Bio 334 - Neurobiology I - Organization of the nervous system 3 http://neurowww.cwru.edu/faculty/strowbridge/OlfactoryBulb/bulb1.htm http://www3.unil.ch/wpmu/neuroaudio/resaerch/auditory-cortex/

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Hierarchichal processing within functional systems – is there really a hierarchy?

Felleman DJ, Van Essen DC. Distributed hierarchical processing in the primate cerebral cortex. Cerebral Cortex (1991) http://www.cse.buffalo.edu/~rapaport/575/F07/006010.jpg 26th August 2013

Bio 334 - Neurobiology I - Organization of the nervous system 3

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Plasticity – changes in strength of connections not reflected in simple anatomy ●

In congenitally blind people, primary visual cortex is active during sentence comprehension task

http://www.pnas.org/content/108/11/4429.long

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Bio 334 - Neurobiology I - Organization of the nervous system 3

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Assignment on disorders ●

1 page write-up – in layman language

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Description of disorder

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Present understanding of the cause?

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What does this tell us about the brain?

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Caveats

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Send by email before the 2nd of September

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