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.

When it comes to Cortex… Size DOES Matter If flattened, a human cortex would cover about four pages of your textbook. 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 Your brain is one of the first organs to develop 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.

2 hemispheres are divided into 4 lobes key words: cerebral cortex; lobes; frontal; parietal; temporal; occipital

Frontal Lobe 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) key words: cerebral cortex; lobes; frontal; motor functions Frontal lobe is not directly involved in sensation or perception. Its functions are related to motor action (behavior). The motor cortex is the start of nerves that run through the spinal cord to the muscles. Broca’s area organizes sequences of speech movements. Damage leads to productive aphasia Dorsolateral Prefrontal Cortex is important in working memory. WM is short term memory for information needed to maintain a context, to prepare for the next step in a sequence of thought, and /or to inhibit irrelevant responses The wisconsin card sorting task illustrates the importance of working memory in maintaining context and inhibiting irrelevant responses

Temporal Lobe Contains primary auditory cortex – interprets hearing info Receives info on auditory, visual patterns speech recognition face recognition (Fusiform Gyrus) word recognition memory formation

Occipital Lobe Input from Optic nerve Contains primary visual cortex Makes sense of visual info

Parietal Lobe Contains primary somatosensory cortex “skin” sense of touch and temperature. Processes body position Sends info to Frontal lobe to help in: hand-eye coordination eye movements attention

Lobes of the Cortex Frontal lobe—largest lobe, voluntary muscle movements, involved in thinking, planning, emotional control Temporal lobe—auditory information Occipital lobe—visual information Parietal lobe—sensory information from your body

BOREDOM BUSTER! Let’s Review with Pinky & The Brain. Why Not Make Your Own Song to Remember? Like This!

Motor & Somatosensory Cortex

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.

Association Areas of the Cortex More intelligent animals have increased "uncommitted" or association areas of the cortex. These areas used for integrating and acting on information received and processed by sensory areas. Allows for learning, thinking, memory & adaptability

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. Example: Broca first discovered this area when he had a patient with damage to this area who could only say “tan” Wernicke’s Aphasia – Damage to Wernicke’s Area would cause a person only to be able to speak in meaningless words. Example: 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