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Psychology (9,541)
PSYC55H3 (6)
Andy Lee (6)
Chapter 3

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University of Toronto Scarborough
Andy Lee

Chapter 3: Neuroanatomy and Development  Sylvian Fissure- the division that separated the temporal lobe from the frontal and parietal lobes Neuroanatomy  Neuroanatomy- the study of the nervous system  Occurs at two levels 1. Gross neuroanatomy- which focuses on general structures and connections visible to the naked eye 2. Fine neuroantomy ( microscopic neuroantomy)- describes the organization of neurons and their connections and sub cellular structure  Dura mater-consists of dense layers of colagenous fibers “hard mother”  Gryi- the protruded rounded surfaces seen in the cortex of the CNS  Sulci- the smaller invaginations ( creases) in the CNS and fissures – the larger invaginations  Gray matter- forms a continuous cortical sheath enshrouding a seemingly homogenous mass of white matter o Contains cell bodies of neurons and glial cells  White matter- appears white due to the fatter tissue called my lien sheaths surrounding the axons  Tracts- bundles of axons Microanatomy and Histology: Cell Staining and Tract Tracing  Histology – is the study of tissue structure through microscopic techniques o Used to identify patterns of connectivity in the nervous system  Neurons are not wired together in a simple, serial circuit  A single cortical neuron is likely to be innervated ( receive inputs) from a large number of neurons  Axons from these input neurons can originate in widely distributed regions  There is a large amount of convergence and divergence in which a single neuron can receive inputs from many neurons and or project to multiple neuron targets  Axons are short projections from neighboring cortical cells…but some can be quite long o Descending below the cortical sheath into the white matter traveling through long fibre tracts and then entering another region of cortex, subcortical nucleus or spinal layer to synapse on another neuron  Neighbouring and distant connections between two cortical regions are referred to as Corticocortical connections.  Stains- chemicals of various sorts that are selectively absorbed by specific neural elements o Staining methods were discovered by trial and error  Tract tracing methods- permit connections between different neurons and brain regions to be identified o Degeneration method- used to trace axonal pathway that are degenerating following damage or disease o The Machi Stain- selectively stains myelin in degenerating axons o HRP is a retrograde tracer-> taken up by the axons when it is injected at axon terminals and transported back to their cell bodies …provides a tool to visualize where the input to a particular neural region originates o Golgi stain- allows an entire cell to be visualized o Nissl stain-stains rough endoplasmic reticulum  Cytoarchitectonic map- applying stains to the entire surface of the cortex and obtaining a picture of regional variations in cellular architecture  Central nervous system- (CNS)- consists of the brain and the spinal cord  Peripheral Nervous system- (PNS)- consists of the everything outside the CNS o Delivers sensory information to the CNS and carries motor commands of the CNS to the muscles Cerebral Cortex  Cerebral cortex- has two symmetrical hemispheres that consist of large sheets of layered neurons separated by the longitudinal fissure  The cerebral cortex, basal ganglia and the diencephalon form the forebrain  Thickness of the cortex is about 3mm o Contains cell bodies of neurons, their dendrites and their axons and axon terminals Anatomical Subdivisions  The cerebral hemisphere has 4 lobes (sometimes a fifth is said to be referred to the limbic system known as the limbic lobe) o Frontal o Parietal o Temporal o Occipital  Connections between the cerebral hemispheres are the axons from cortical neurons that travel through the Corpus Callosum (“hard body”) which represents the largest white matter Commisure -- the white matter tracts that cross from the left to the right side or vice versa of the CNS Cytoarchitectonics-> the method of subdividing…has to do with how cells in a region appear morphologically and are arranged with respect to each other…these investigations entail the performance of detailed histological analysis of the tissue from different regions of the cerebral cortex  Goal: to define the extent of regions in which the cellular architecture looks similar and therefore might indicate a homogenous area of the cortex that represents, perhaps a mogeneous area of the cortex that represents a functional area  Neocortex- comprises 90% of the cerebral cortex o contains 6 main cortical layers with a high degree of specialization of neuronal organization o includes areas such as the primary sensory and motor cortex and association cortex  Mesocortex – has 6 layers, refers to the paralimbic region which includes the cingulated gyrus, parahippocampal gyrus , insular cortex and the orbitofrontal cortex  Allocortex- only has 1-4 layers of neurons and includes the hippocampal complex and the primary olfactory cortex Functional Divisions  Motor areas of the frontal lobe- plays a major role in the planning and execution of movements  Two main subdivisions: o Motor cortex- begins in the central sulcus and extends in the anterior direction  Contains motor neurons whose axons extend to the spinal cord and the brainstem and synapse on motor neurons in the spinal cord o Prefrontal cortex – takes part in the more complex aspects of planning and executing behaviour—tasks that require the integration of information over time  Somatosensory areas of the parietal lobe- receives input from the somatosensory relays of the thalamus and represent information about touch pain, temperature sense and limb proportion  Visual Processing Areas in the Occipital Lobe- receives visual inputs relayed from the lateral geniculate nucleus of the thalamus o visual information from the outside worl
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