The Cerebral Cortex

The Evolving Brain• Different animal species

have many structures in common, including a cerebellum and cortex.

• The cortex is much larger in mammals than in species that evolved earlier, such as fish and amphibians.

• The cross section of the human brain shows how the cerebral cortex has developed around and above more primitive brain structures.

Areas of the Cortex

• More intelligent animals have increased "uncommitted" or association areas of the cortex.

• These vast areas of the brain are responsible for integrating and acting on information received and processed by sensory areas.

When it comes to Cortex…Size DOES Matter

• If flattened, a human cortex would cover about four pages of this book.

• A chimpanzee's would cover one page

• a monkey's a postcard

• a rat's a postage stamp.

• From Scientific American, October 1994, p. 102.

Developing Brain

•Neural tube—beginning of nervous system develops at 2 weeks after conception

•Neurogenesis—development of new neurons

Forebrain Structures

Largest Brain Region with the most complex

structures.

What separates us from the beasts.

Cortical Specialization

• Localization—notion that different functions are located in different areas of the brain

• Lateralization—notion that different functions are processed primarily on one side of the brain or the other

• Left & Right sides are separate

• Corpus Callosum : major pathway between hemispheres

• Some functions are ‘lateralized’– language on left– spacial relations, music on

right

• Lateralization is never 100%

Brain has 2 Hemispheres

LeftHemisphere

Corpus CallosumRight

Hemisphere

Lateralization of the Hemispheres

An Example of Spacial Relations

Answer: E

Each hemisphere is divided into 4 lobes

Frontal

Parietal

Occipital

Temporal

MotorCortex

FrontalLobe

Frontal Lobe

MotorCortexMotorCortexBroca’s

Area

•Contains primary motor cortex•Important in judgment, planning and sequencing areas•Controls emotional center of the brain (limbic system)•Contains Broca’s area for speech

•Prefrontal area for working memory (Short-Term Memory) – helps you remember what you just did so you know what to do next (sequencing)

Temporal Lobe

TemporalLobe

TemporalLobe

AuditoryCortex

•Contains primary auditory cortex – interprets hearing info

•Inputs are auditory, visual patterns

–speech recognition

–face recognition (Fusiform Gyrus)

–word recognition

–memory formation

•Outputs to limbic System, Basal Ganglia, and brainstem

Occipital Lobe• Input from Optic

nerve• Contains primary

visual cortex– Makes sense of visual

info

• Sends info to parietal and temporal lobes

OccipitalLobe

VisualLobe

ParietalLobe

SomatosensoryCortex

Parietal Lobe

•Receives info from multiple senses

•Contains primary somatosensory cortex

your “skin” sense of touch and temperature.

•Sends info to Frontal lobe to help in:

• hand-eye coordination

• eye movements

• attention

Lobes of the Cortex• Frontal lobe—largest lobe, produces

voluntary muscle movements, involved in thinking, planning, emotional control

• Temporal lobe—primary receiving area for auditory information

• Occipital lobe—primary receiving area for visual information

• Parietal lobe—processes sensory information from your body information

BOREDOM BUSTER!

Let’s Review with Pinky & The Brain.

Motor Cortex: Located at the back of the Frontal Lobe.

The more precise movements, the more motor cortex the part uses up.

Sensory Cortex:

Located at the front of the Parietal Lobe.

The more sensitive the area, the more sensory cortex it uses up.

Language and the Brain

• Aphasia—partial or complete inability to articulate ideas or understand language because of brain injury or damage

• Broca’s area—plays role in speech production

• Wernicke’s area—plays role in understanding and meaningful speech

Aphasias• Broca’s Aphasia – Damage to Broca’s Area causes a person

to struggle formulating words while still being able to comprehend speech.

• Wernicke’s Aphasia – Damage to Wernicke’s Area would cause a person only to be able to speak in meaningless words.

• Example of Wernicke’s Aphasia: Asked to describe a picture of two boys stealing cookies from behind a woman’s back, a patient responded,

• “Mother is away her working her work to get her better, but when she’s looking the two boys looking the other part. She’s working another time.”

• Mnemonic to remember: You can't read Wernicke's words and Broca's makes you babble

Language Areas of the Brain

How We Read Out Loud