Tour through Brain part 2

Pages 132-135A.P. 85-90

OBJECTIVES: The Student Will=

• Describe the 3 parts of the Limbic System• Analyze the Cerebrum into 4 cortex

categories…focusing on the senses

Limbic system

• Amygdala (uh-Mig-dul-uh)+ Hippocampus+ Cerebrum= Limbic System

• Limbic Latin for border• Forms a border for high and low parts of the

Brain• Structures in region we share with other

animals, rage, fear

Part 1:Amygdala (uh -Mig-dul-uh)

• Greek for Almond• Evaluating sensory information• Determines emotional importance- initial

decision• F.E. assesses danger or threat• Mediates anxiety and depression• Supporting evidence=Because PET Scans

show increased neural activity in Amygdala

Part 2: Hippocampus

• Limbic System component• Latin for sea horse• Compares sensory information from what it

knows about the world• Memory system• Tells RAS to cool it• you don’t freak out at every car drives by,

bird chirps, saliva goes down throat

The hippocampusResponsible forStorage of new information in memory

Comparing sensory information with what the brain expects about the world

Enabling us to form spatial memories for navigating the environment

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Hippocampus cont

• Gateway to memory • Spatial memories• As a result actively navigate through

environment• Spatial- relating to, occupying, or happening

in space

More Hippo.

• With adjacent parts of brain forms new memories, facts and events

• F.E. identify flower, tell story, recall vacation or trip

• Meet person yesterday remember, tone of voice, appearance, location

• Without Hippo could not get info to destinations

How do we know= Subject H.M. (his story is the evidence)

• Brain damaged patients with memory problems

• Patient H.M. having life threatening epilepsy• Epilepsy- Neurological disorder, many causes

and forms, have seizures• Removed Amygdala and most of Hippo• Surgery successful, milder, seizures, control

with meds….But

Memory effected Profoundly

• Remembered everything Before the surgery, However he could not remember anything past 15 minutes.

• Vanished like water down the drain• Because Hippo removed= lost memory• Could acquire new physical skills, problem solving

skills. F.E. playing tennis, puzzles• But could not remember the training sessions in

which he learned these skills!

H.M. cont…

• Could not remember days of week, year, read same magazine over and over

• Stuck in time warp of the past• Doesn't know scientists that have studied him

for decades• Long-term memory problems• Memories need period of time, consolidation,

to stabilize the memory

3rd part: Cerebrum

• Largest part of brain• Higher thinking takes place• Looks like cauliflower • Creatively controls the environment over

animals• Cerebrum divided into halves called Cerebral

hemispheres

The cerebrumLargest brain structure

Two cerebral hemispheres connected by the corpus callosum.

In charge of most sensory, motor, and cognitive processes

Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter)

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Cerebrum Cont…

• Hemispheres connected by bands of fibers called Corpus Callosum (CORE-pus- ca-LOW-suhm)

• Left side controls right side of body and vise versa

• However two hemispheres have different talents and tasks, called Lateralization

Cerebral Cortex

• Thin layer of dense packed cells, cover Cerebellum

• Top of the Brain! • Latin for bark• Produce grey tissue so grey matter• 1/8th of inch thick• But ¾ of cells in human brain

Lobes of the cerebral cortex

Occipital lobes (visual cortex)Parietal lobes (somatosensory cortex)Temporal lobesMemory, perception, emotion, and auditory cortexLeft lobe: Wernicke’s areaFrontal lobesEmotion, planning, creative thinking, and motor cortexLeft lobe: Broca’s area

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Lobes of the Cortex

• 4 distinct regions• Occipital (ahk-SIP-uh-tuhl) lobes• Back of head, visual cortex= vision• Visual signals processed • Damage to visual cortex impair vision,

blindness

Parietal Lobes

• Somatosensory cortex• Receives information about pressure, pain,

touch, temp.• Signals from hands, face• Attention and mental operations

Temporal Lobes

• Latin for temples• Sides of brain, just above the ears• Contain audio cortex- processes sounds• Wernicke’s area- involved in language

comprehension

Frontal lobes

• Front of brains cerebral cortex• Motor cortex, controls 600 muscles in body• Short term memory, higher order thinking,

initiative, social judgment• Broca’s Area- speech production

Lobes of the cerebral cortex

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Cortex cont…

• Stimulate with electrical current to parietal lobes= feel in skin; visual cortex, oct. lobes= flash, light

• But some areas stimulated do nothing association cortex, higher mental process

• Prefrontal cortex- barely exists in mice, 7 % in dogs, but 29% in humans

Your turn

Jenny bumps her head and is suddenly unable to see, although the doctor says there is nothing wrong with her eyes? Which part of her brain did Jenny damage?1. The amygdala2. The hippocampus3. The occipital lobe of the cerebral cortex4. The parietal lobe of the cerebral cortex

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Your turnJenny bumps her head and is suddenly unable to see, although the doctor says there is nothing wrong with her eyes? Which part of her brain did Jenny damage?1. The amygdala2. The hippocampus3. The occipital lobe of the cerebral cortex4. The parietal lobe of the cerebral cortex

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Phineas GageGage was a railroad construction foreman

An 1848 explosion forced a steel tamping rod through his head

Others said he was “no longer Gage”

Lost his job, worked as a sideshow exhibit

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Summary Brain part 2

• Limbic system; amygdala, hippo( gage), hypo.• 4 cortexes