Organization of the nervous system 2 Raghav Rajan Bio 334 Neurobiology I August 22nd 2013 1
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) INFERIOR (below) http://www.rci.rutgers.edu/~uzwiak/anatphys/apfalllect19.html 2
Medial lateral axes LATERAL (away from the midline) MEDIAL (near the midline) LATERAL (away from the midline) 3 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) CONTRALATERAL (opposite side) 4 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 5
Divisions of the nervous system http://serendip.brynmawr.edu/exchange/brains/structures 6
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 7
Basal ganglia consist of 4 nuclei Striatum Pallidum Substantia nigra Subthalamic nucleus Kandel, Schwartz and Jessell, Principles of Neural Science 8
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 involved in other functions too Kandel, Schwartz and Jessell, Principles of Neural Science 9
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/jou rnal/v466/n7306/full/nature09159.h tml#supplementary-information 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 10
Songbirds have served as a good model system for understanding the function of these loops Evolutionarily conserved neuronal morphology, molecular markers, activity patterns, connections Specialized portion of this loop appears to be involved only in song learning http://www.nbb.cornell.edu/goldberg/ Doupe AJ et al. Songbirds could teach basal ganglia research a new song. Trends in Neurosciences 2005 11
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 12
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 13
Hippocampus and associated structures are involved in learning and memory 14 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 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 15 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 16
Thalamus is the gateway to the cortex All sensory (except olfactory) are relayed to the cortex through the thalamus Thalamo-cortico-thalamic loops are believed to be important for consciousness 17 Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) Chapter 7
Midbrain gives rise to tectum and tegmentum Tectum consists of superior and inferior colliculus Superior Colliculus gets information from eye and controls eye movements Inferior colliculus gets information from the ears 18 Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) Chapter 7
Midbrain gives rise to tectum and tegmentum Tegmentum consists of red nucleus and substantia nigra Both are involved in controlling voluntary movement Corticospinal tract passes through the midbrain 19 Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) Chapter 7
Rostral hindbrain gives rise to cerebellum and pons 20 Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) Chapter 7
Caudal hindbrain gives rise to medulla 21 Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) Chapter 7
Cerebellum is again involved in modifying movements 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 uncoordinated movements 22 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. Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) 23
Medulla Has motor neurons that control the tongue Receives a lot of sensory information from various senses A number of other autonomous functions Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) 24