Cerebral Cortex

Brian J. Piper, Ph.D.

Phineas Gage: http://www.youtube.com/watch?v=WGl5SUB8IXM

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The Brain

•The Cerebral Cortex• Our Divided Brain• Right-Left Differences in the Intact Brain

Neuroanatomy OverviewThe cerebral cortex is the intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the body’s ultimate control and information processing center.

Structure of the Cortex

Each brain hemisphere is divided into four

lobes that are separated by

prominent fissures. These lobes are the

frontal lobe (forehead), parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of

head).

Cortical Divisions

• Sulcus, Fissure-valley

• Gyrus- swelling

Functions of the Cortex

The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements. The Sensory Cortex (parietal cortex) receives

information from skin surface and sense organs.

Sensory Homunculus

• This is a representation of the brain space given to each bodily area

Visual Function

The functional MRI scan shows the visual cortex is active as the

subject looks at images. C

ourtesy of V.P. C

lark, K. K

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Maisog, S. C

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ngerleider, and J.V. H

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ational Institute of Mental H

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Auditory Function

The functional MRI scan shows the

auditory cortex is active in patients who

hallucinate.

LanguageAphasia is an impairment of language,

usually caused by left hemisphere damage either to Broca’s area (impaired speaking)

or to Wernicke’s area (impaired understanding).

Specialization & Integration

Brain activity when hearing, seeing, and speaking words

The brain is sculpted by our genes but also by our experiences.

Plasticity refers to the brain’s ability to modify itself after some types of injury or illness.

The Brain’s Plasticity

Phantom Limbs

• V.S. Ramachandran has worked with amputees that have pain from their former limb

• Foot fetish• Limb reattachments

Our Divided Brain

Our brain is divided into two hemispheres. The left hemisphere processes reading,

writing, speaking, mathematics, and comprehension skills. In the 1960s, it was

termed as the dominant brain.

Splitting the BrainA procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers

(mainly those of the corpus callosum) between them.

Corpus Callosum

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Courtesy of T

erence William

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Split Brain Patients of Michael Gazziniga

With the corpus callosum severed, objects (apple) presented in the right visual field can be named.

Objects (pencil) in the left visual field cannot.

Divided Consciousness

Long-Video (11 Min): http://www.youtube.com/watch?v=0lmfxQ-HK7Y

Try This!

Try drawing one shape with your left hand and one with your right hand,

simultaneously.B

BC

Right-Left Differences in the Intact Brain

People with intact brains also show left-right hemispheric differences in mental

abilities.

A number of brain scan studies show normal individuals engage their right

brain when completing a perceptual task and their left brain when carrying out a

linguistic task.

“Only left-handers are in their right mind.”

Right Left

Left 95%

Right 5%

Handedness

LanguageCenter

Left-handers are more likely to have their language center in their right

cortex

Right Left

Left 95% 70%

Right 5% 30%

Handedness

LanguageCenter

Phineas Gage (1823-1860)

• An accident resulted in severe damage to his left-frontal lobe.

• He survived but “was no longer Gage”

• Records are sparse but he may have adapted.

Is this appropriate?

• http://www.youtube.com/watch?v=PFJPtVRlI64

• Anterior commissure: the anterior (frontal) part of the corpus collosum

Animal Research

• Reduce #

• Reduce discomfort

• Use alternatives

Review: 1. What type of test?

2. Correlations

3.

• Clinical versus counseling psychologist

4.

• A researcher conducts a study on how viewing sexually explicit material influences attitudes towards women. Participants are assigned to groups and then complete a survey about their attitudes.– Independent variable:– Dependent variable:– Design:

5.

• A researcher gives a survey to all of his friends. – Type of research?– Problem(s)?

6. Brain Structure

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c.d.

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f.g.

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6. Brain Structure