Human brain

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Information about Human brain

Published on September 30, 2013

Author: raniashok


Mrs. Rani Ashok Assistant Professor of Zoology Lady Doak College, Madurai – 2 Email: : Mrs. Rani Ashok Assistant Professor of Zoology Lady Doak College, Madurai – 2 Email: Human Brain PowerPoint Presentation: THE BRAIN Most complex organ of the body Only weighs 1,300 grams Contains billions of neural networks that interact to create human behaviour Forebrain: Forebrain Cerebrum and Cerebral cortex Left and Right Hemispheres Left hemisphere for most people is the dominant hemisphere- responsible for production of language, mathematical ability, problem solving, logic Right hemisphere thought to be responsible for creativity and spatial ability PowerPoint Presentation: (Barlow and Durand , 2005) Frontal Lobe: Frontal Lobe Located at the front of both cerebral hemispheres Primary motor cortex Pre-motor cortex Broca’s Area- Motor Production of speech Complex Functioning- personality, judgement, insight, reasoning, problem solving, abstract thinking and working memory The Cerebral Cortex: The Cerebral Cortex Aphasia impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding) –see clips Broca’s Area an area of the left frontal lobe that directs the muscle movements involved in speech Wernicke’s Area an area of the left temporal lobe involved in language comprehension and expression PowerPoint Presentation: ( Parietal lobe: Parietal lobe Located behind frontal lobe Somatosensory cortex Spatial orientation, perception and comprehension of language function recognising object by touch Links visual and somatosensory information together Neglect Temporal Lobes: Temporal Lobes Located at each side of the brain Involved in receiving and processing auditory information , higher order visual information, complex aspects of memory and language Wernicke’s Area- Comprehension of speech Occipital lobes: Occipital lobes Rearmost portion of the brain Visual processing area Corpus Callosum- Fibre bundle in the brain that connects the two hemispheres together. Occipital Lobe – Cortical Regions: Occipital Lobe – Cortical Regions Primary Visual Cortex – This is the primary area of the brain responsible for sight -recognition of size, color, light, motion, dimensions, etc. Visual Association Area – Interprets information acquired through the primary visual cortex. PowerPoint Presentation: Cortical Regions A. B. C. D. E. F. G. H. I. J. K. A. Primary Motor Cortex/ Precentral Gyrus B. Broca’s Area C. Orbitofrontal Cortex K. Primary Somatosensory Cortex/ Postcentral Gyrus I. Primary Gustatory Cortex J. Somatosensory Association Cortex G. Primary Visual Cortex H. Visual Association Area E. Primary Auditory Cortex F. Wernike’s Area D. Primary Olfactory Cortex (Deep) Diencephalon: Diencephalon Thalamus - filters sensory information, controls mood states and body movement associated with emotive states Hypothalamus - ‘Central control’ for pituitary gland. Regulates autonomic, emotional, endocrine and somatic function. Has a direct involvement in stress and mood states. ( Hindbrain: Hindbrain Cerebellum - regulates equilibrium, muscle tone, postural control, fine movement and coordination of voluntary muscle movement. Pons - Relay station between cerebrum and cerebellum PowerPoint Presentation: ( ) PowerPoint Presentation: Medulla oblongata- Conscious control of skeletal muscles, balance, co-ordination regulating sound impulses in the inner ear, regulation of automatic responses such as heart rate, swallowing, vomiting, coughing and sneezing Reticular Formation- Important in arousal and maintaining consciousness, alertness attention and Reticular Activating System which controls all cyclic functions i.e. respiration, circadian rhythm. PowerPoint Presentation: Basal Ganglia- Control of muscle tone, activity, posture, large muscle movements and inhibit unwanted muscle movements. Substatia Nigra- Produces dopamine is connected to the basal ganglia. – EPSE’s (Barlow and Durand , 2005) The Limbic system: The Limbic system Amygdala - mediates and controls major affective mood states such as friendship , love, affection, fear, rage and aggression. Hippocampus - Memory, particularly the ability to turn short term memory into long term memory. Alzheimer's disease. (Barlow and Durand , 2005) Brain Lateralization: Brain Lateralization Our Divided Brains: Our Divided Brains Corpus collosum – large bundle of neural fibers (myelinated axons, or white matter) connecting the two hemispheres Hemispheric Specialization: Hemispheric Specialization LEFT Symbolic thinking (Language) Detail Literal meaning RIGHT Spatial perception Overall picture Context, metaphor Contra-lateral division of labor: Contra-lateral division of labor Right hemisphere controls left side of body and visual field Left hemisphere controls right side of body and visual field Split Brain Patients: Split Brain Patients Epileptic patients had corpus callosum cut to reduce seizures in the brain Lives largely unaffected, seizures reduced Affected abilities related to naming objects in the left visual field Brain Plasticity: Brain Plasticity Brain Plasticity: Brain Plasticity The ability of the brain to reorganize neural pathways based on new experiences Persistent functional changes in the brain represent new knowledge Age dependent component Brain injuries Environmental influences on neuroplasticity: Environmental influences on neuroplasticity Impoverished environment Enriched environment Sensation and Perception: Sensation and Perception Sensation: Sensation The process by which the central nervous system receives input from the environment via sensory neurons Bottom up processing Perception: Perception The process by which the brain interprets and organizes sensory information Top-down processing The psychophysics of sensation: The psychophysics of sensation Absolute threshold  the minimum stimulation needed to detect a stimulus with 50% accuracy Subliminal stimulation  below the absolute threshold for conscious awareness May affect behavior without conscious awareness Sensory adaptation/habituation  diminished sensitivity to an unchanging stimulus The five major senses: The five major senses Vision – electromagnetic Occipital lobe Hearing – mechanical Temporal lobe Touch – mechanical Sensory cortex Taste – chemical Gustatory insular cortex Smell – chemical Olfactory bulb Orbitofrontal cortex Vomeronasal organ? The sixth sense: The sixth sense Vestibular  balance and motion Inner ear Proprioceptive  relative position of body parts Parietal lobe Temperature  heat Thermoreceptors throughout the body, sensory cortex Nociception  pain Nociceptors throughout the body, sensory cortex And the seventh…and eighth…and ninth… Protection and Blood Supply: Protection and Blood Supply Meninges - Dura mater and Pia mater CSF - 2 main functions ; shock absorption and mediation of blood vessels and brain tissue in exchange of nutrients. Circle of Willis – carotid arteries and baliser arteries. Blood brain Barrier- Protect the brain from chemicals in the blood. Made up of tightly packed Endothelial cells/capillaries making it difficult to penetrate. ( ) Structure of a Neuron: Structure of a Neuron ( This image has been released into the public domain by its author, LadyofHats . This applies worldwide.) Function of a Neuron: Function of a Neuron Resting potential - positive/negative charge - voltage gated channels -sodium/potassium pump Action potential - threshold -depolarisation (This image has been released into the public domain by its author) PowerPoint Presentation: (Rosenweig, Breedlove and Leiman ,2005 pg 64 ) Action potential Synaptic transmission: Synaptic transmission Calcium ion channels Synapse Lock and key effect reuptake (This image has been released into the public domain by its author) Neurotransmitters: Neurotransmitters Acetylcholine (ACh ) Release through the brain via cholinergic pathways. Plays role in: - cognition (memory) - sleep/wake cycle - parasympathetic nervous system - regulation of heart rate, digestion, production of saliva,bladder function. - smooth muscle contraction ( Boyd, 2002 ) Monoamines: Monoamines Norepinephrine (NE) Found mainly in 3 areas of the brain; the locus coeruleous, the pons and reticular formation. Main role; - attention, alertness, arousal -sleep/wake cycle - regulating mood/anxiety (Barlow and Durand ,2005) PowerPoint Presentation: Almost a million nerve cells in the brain contain dopamine. Role in ; - complex movement -cognition - motor control - emotional responses such as euphoria or pleasure. Newer antipsychotic medication focus on particular dopaminergic pathways in the brain. Lessening EPSE’s. (Barlow and Durand ,2005) Dopamine (DA) PowerPoint Presentation:  Believed to be one of the great influences on behaviour. Complex neurotransmitter. Surprisingly only 2% of serotonin is found in CNS. Roles include - Vasoconstriction, gastrointestinal regulation. - Low serotonin associated with aggression, suicide, impulsive eating, anxiety and low mood. - regulates general activity of the CNS, particularly sleep. - Delusions, hallucinations and some of the negative symptoms of schizophrenia. (Barlow and Durand ,2005) Serotonin (5HT ) Amino Acids: Amino Acids Glutamate - found in all cells - controls opening of ion channels - blocking glutamate produces psychotic symptoms - Over exposure to glutamate causes cell death GABA ( Gamma-aminobutyric acid) - Only found in CNS - Inhibitory neurotransmitter - controls excitatory neurotransmitters - Implicated in anxiety disorders Neuro-Histology: Neuro-Histology Golgi Staining Select Neurons Golgi Type I Neurons Golgi Type II Neurons Neuro-Histology: Neuro-Histology Nissl Stain Select for Cell Body and organelles Neuro-Histology: Neuro-Histology Myelin Staining White Matter –Axons Gray Matter- Cell Bodies Neuro-Histology: Neuro-Histology Horseradish Peroxidase Cells absorb and transfer stain Can map neural networks Electrical Scanning: Electrical Scanning Electroencephalogram (EEG) Activity of Pyramidal Cortex Cells Evoked Potentials Brainstem Auditory Evoked Response (BAER) Visual Evoked Potential Somatosensory Conduction EEG Patterns: EEG Patterns Delta Wave <0.5-4 Hz Deep Sleep Theta Wave 4-7 Hz Drowsy and Sleep Alpha Wave 8-12 Hz Awake and restful Beta Wave 12-35 Hz Focused and Active High, Mid, Low Gamma Wave 35+ Hz Peak Hyperarousal Radiological Scanning: Radiological Scanning Pneumoencephalography Drain CSF through Lumbar Puncture Inject sterile air/gas into space Take x-ray CT Scan Take multiple x-ray slices Reconstruct slices into 3-D image Radiological Scanning: Radiological Scanning Angiogram SPECT Glucose Metabolism PET Glucose Metabolism Radiological Scanning: Radiological Scanning Magnetic Resonance Imaging July 3, 1977 the first MRI performed on a human Hydrogen nuclei (protons) spinning randomly A strong magnetic field is applied causing the protons to line up A radio pulse applied causing the protons to flip their spin (resonate) When the signal is removed, the protons return to their natural alignment with the magnetic field and release excess stored energy Coils pick up the released energy which is transformed into images. Different types of tissues (normal and abnormal) give off different signals and are easily differentiated Radiological Scanning: Radiological Scanning Functional MRI ( f MRI) Hydrogen protons emit a different resonance signal in blood depending on level of oxygenation Difference in signals (Blood Oxygen Level Dependent-BOLD) Superimpose images on a structural MRI during activity PowerPoint Presentation: Thank You

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