13- Brain and Behavior

13- Brain and Behavior - Brain and Behavior Brain and...

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Unformatted text preview: Brain and Behavior Brain and Behavior Major divisions of the of the nervous system Peripheral Nervous System Central Nervous System Organization of the brain Major divisions Topographic organization Information processing in the brain Language Circadian rhythms and sleep And as it works, the industrious bee computes it’s time as well as we. How could such sweet and wholesome hours be reckoned but with herbs and flowers Andrew Marvell (1621­1678) The Birds A nd th e Be e s Dance Language of the Bees The Round Dance When a bee finds a food source some distance from the hive, he can return to the hive and, through dance, can communicate the direction (with respect to the sun) and the distance of the food source. The movement of the sun across the sky is compensated for by the bee’s internal, biological clock. The Waggle Dance A vertical waggle indicates directly towards the sun Time ­CompensatedSun Compass Orientation The Dancing Bees Nervous System Central and Peripheral Nervous Systems 1011 – 10 12 neurons Central Nervous System = Brain and Spinal Cord Peripheral Nervous System = Cranial and Spinal Nerves 106 neurons Bee Nervous System Peripheral Nervous System Peripheral Nervous System The somatic nervous system includes sensory input and motor output for sensory input and motor output for voluntary movements The autonomic nervous system carries “motor” output that regulates internal organs – smooth muscle, cardiac muscle, glands Simple Spinal Reflex Simple Spinal Reflex A sharp rap on the tendon causes stretch of the quadriceps. This initiates action potentials in mechanoreceptors that are sensitive to muscle stretch. These stretch receptors excite motor neurons that innervate the quadriceps (causing it to contract) as well as interneurons that inhibit the motorneurons that innervate the antagonistic muscle Major Divisions of the Brain Major Divisions of the Brain • Brain Stem – Medulla (autonomic functions cardiac, respiratory) – Pons and Cerebellum (timing and pattern of muscle activity during movement) – Midbrain (eye and other motor movement) • Diencephalon – Thalamus (relay of sensory input to cortex) – Hypothalamus (endocrine regulation, sleep, body temperature, etc) • Cerebrum (perception, learning and memory, higher motor control) – Basal Ganglia (control of complex movements) – Cerebral Cortex (higher motor function, perception, learning and memory) Cerebrum Basal nuclei: centers for planning and learning movements Corpus collosum: transmission of information between left and right sides of the brain Organization of the Cerebral Cortex Organization of the Cerebral Cortex Central Sulcus Functional Divisions: Sensory cortex: An area of the brain directly committed to sensation Motor Cortex: An area directly committed to directing motor output Association cortex: Integration of diverse information for complex perception, movements, learning and memory Sylvian Fissure Anatomical Divisions: Occipital, Parietal, Temporal, Frontal Topographic Organization in Motor and Topographic Organization in Motor and Sensory Cortex Parts of the body map in an orderly fashion to the cortex. The suface area devoted to each body part depends on the number of sensory neurons, not on the size of the part, distorting the map. Information Flow in the Nervous System Sensory Input Primary Sensory Cortex Higher Order Sensory Cortex Association Cortex Higher Order Motor Cortex Primary Motor Cortex Motor Output Human Language as an Example Human Language as an Example • How do we associate brain regions with specific functions? – – – – Anatomical tracing of neural pathways Effects of lesions Imaging Brain stimulation • How might the brain organize information flow for a complex task such as repeating a spoken or written word? Visual and Auditory Pathways: Anatomical Traces of Visual and Auditory Pathways: Anatomical Traces of Simple Pathways Thalamus Thalamus Partial or Complete Loss of Language Ability Our earliest understanding of the brain areas that are involved in language comes from individuals with brain lesions caused by stroke or injury. Damage to specific regions of the brain can cause various problems with language ability – for example, a loss of comprehension of the spoken word and difficulty in forming meaningful speech (Wernicke’s Aphasia) or an inability to speak without loss of comprehension (Broca’s Aphasia) Aphasia: First Demonstration of Localization of Brain Function Broca’s Aphasia: Inability to Speak Broca’s Aphasia: Inability to Speak Sylvian Fissure Broca’s Area is a region of Higher Order Motor Cortex Depending on the Depending amount of damage Individuals with Broca's aphasia may be completely amount Individuals unable to use speech, or they may be able to use single-word statements or even full sentences, though these sentences may require a great deal of effort to construct. Comprehension is not impaired. great Wiernicke’s Aphasia: Wiernicke’s Aphasia Wernicke’s patients have a normal ability to articulate words and phrases, but they are nonsensical with regard to meaning. Comprehension is impaired. For example, the quote below is a response from a Wernicke’s patient to “I want to ask you a few…?” “Oh sure, go ahead, any old think you want. If I could I would. Oh, I’m taking the wrong way to say all of the barbers here whenever they stop you it’s going around and around, if you know what I mean, that is tying for repuceration. Well, we were trying the best that we could while another time it was with the beds over there the same thing.” Broca’s Area Brain from a Patient with Wernicke’s Syndrome Wenicke’s Area is a region of Association Cortex Language and the Brain Language and the Brain Motor Programs For Articulation Recognition of form and Meaning of Words Another Approach: Modern Imaging Methods Allow Us to Visualize Brain Activity in Humans PET Scans: Measure Metabolic Activity in the Brain Brain Stimulation Brain Stimulation Stimulation of the brain during surgery Stimulation is another approach to understanding brain organization and function. brain Stimulation of motor cortex can cause a localized movement Stimulation of sensory cortex can cause localized sensation Sites of Brain Stimulation that Affect Sites of Brain Stimulation that Affect Speech Fig. 21.3 Bear, Connors, and Paradiso Lateralization of Language, Lateralization of Language, Bilateral Comprehension The neural components that are involved in speech are located in the left hemisphere of the brain The left visual field projects to the right cerebral hemisphere Model for Information Flow During Language Biological Rhythms as an Example Biological Rhythms as an Example • How does the brain regulate the temporal organization of physiology and behavior Circadian Rhythms: The Basic Phenomenon Circadian Rhythms: The Basic Phenomenon + = Light Cycle Entrained Rhythm Freerunning Rhythm Common Features: Freerunning and Entrainment by Common Features: Freerunning and Entrainment by Light Tracking Down the Biological Clock in Tracking Down the Biological Clock in Mammals: Follow the Light Lesion studies and a pathway trace led to the discovery that some retinal ganglion cell axons emerge from the optic chiasm and form a “retinohypothalamic tract” (RHT) which goes to the “suprachiasmatic nucleus” (SCN) of the hypothalamus Cutting the optic nerves (in front of the optic chiasm) causes the rhythm to freerun. But cutting the optic tracts (behind the optic chiasm)has no effect on entrainment. Lesions that Destroy the SCN Abolish the Daily Lesions that Destroy the SCN Abolish the Daily Rhythm in Activity SCN Lesion Circadian Sleep Disorders in Humans Circadian Sleep Disorders in Humans Entrainment Failure (blindness) Altered Sleep Phase (mutations in clock genes) ...
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This note was uploaded on 11/12/2010 for the course BSCI BSCI 110B taught by Professor Johnson during the Spring '09 term at Vanderbilt.

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