Brain Structure and Function If the human brain
Brain Structure and Function
“If the human brain were so simple that we could understand it, we would be so simple that we couldn’t” -Emerson Pugh, The Biological Origin of Human Values (1977)
Phineas Gage • September 13 th, 1848 • Phineas 25 years old • Rutland & Burlington Railroad, Cavendish, VT • Paving the way for new RR tracks • “Tamping Iron” – 1. 25 in x 3 ft
Phineas Gage • Accident – Quick Recovery • Months later: “No longer Gage” – Before: capable, efficient, best foreman, well-balanced mind – After: extravagant, anti-social, liar, grossly profane • Stint with P. T Barnum • Died 12 years later • Watch Clip
Evolution of the Brain Reptilian Paleomammalian Neomammalian
The Brain • Brainstem – responsible for automatic survival functions • Medulla – controls heartbeat and breathing
Parts of the Brain THALAMUS Relays messages amygdala hippocampus pituitary CEREBELLUM Coordination and balance BRAINSTEM Heart rate and breathing
Reticular Formation • Widespread connections • Arousal of the brain as a whole • Reticular activating system (RAS) • Maintains consciousness and alertness • Functions in sleep and arousal from sleep
The Cerebellum – helps coordinate voluntary movement and balance
The Limbic System • Hypothalamus, pituitary, amygdala, and hippocampus all deal with basic drives, emotions, and memory • Hippocampus Memory processing • Amygdala Aggression (fight) and fear (flight) • Hypothalamus Hunger, thirst, body temperature, pleasure; regulates pituitary gland (hormones)
The Limbic System § Hypothalamus § neural structure lying below (hypo) the thalamus; directs several maintenance activities § body temperature § THE FOUR F’s!!!! § Links nervous & endocrine system § linked to emotion
The Limbic System Show self stimulation clip
The Limbic System • Amygdala – two almondshaped neural clusters that are components of the limbic system and are linked to emotion and fear
August 1 st, 1966 Charles Whitman
The Brain • Thalamus – the brain’s sensory switchboard, located on top of the brainstem – it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla
The Cerebral Cortex • Cerebral Cortex – the body’s ultimate control and information processing center
The lobes of the cerebral hemispheres
The lobes of the cerebral hemispheres Planning, decision making speech Sensory Auditory Vision
The Cerebral Cortex • Frontal Lobes – involved in speaking and muscle movements and in making plans and judgments – the “executive” • Parietal Lobes – include the sensory cortex
The Cerebral Cortex • Occipital Lobes – include the visual areas, which receive visual information from the opposite visual field • Temporal Lobes – include the auditory areas, each of which receives auditory information primarily from the opposite ear
The Cerebral Cortex • • Frontal (Forehead to top) Motor Cortex Parietal (Top to rear) Sensory Cortex Occipital (Back) Visual Cortex Temporal (Above ears) Auditory Cortex
Motor/Sensory Cortex • Contralateral • Homunculus • Unequal representation
Sensory Areas – Sensory Homunculus Figure 13. 10
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
Language Areas • Broca Expression • Wernicke Comprehension and reception • Aphasias LEFT HEMISPHERE
Paul Broca [1800 s] • Suggested localization
Techniques to examine functions of the brain 1. Remove part of the brain & see what effect it has on behavior 2. Examine humans who have suffered brain damage
3. Stimulate the brain 4. Record brain activity
Brain Lateralization
Our Divided Brains • Corpus collosum – large bundle of neural fibers (myelinated axons, or white matter) connecting the two hemispheres
Hemispheric Specialization LEFT RIGHT Symbolic thinking (Language) Detail Literal meaning Spatial perception Overall picture Context, metaphor Right or Left Brain Test
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 • 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 • Video Clip • Go to Split Brain PPT
A Musical Review
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 Video Clip Impoverished environment Enriched environment
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