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 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.

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.

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

Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal

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 somatic information

Motor Cortex Frontal Lobe Frontal Lobe Contains primary motor cortex Important planning and judgement Broca’s area for speech Controls emotions Motor Cortex Motor Cortex Broca’s Area

Temporal Lobe Hearing Perception –speech recognition –face recognition –word recognition z Contains primary auditory cortex Temporal Lobe Temporal Lobe Auditory Cortex

Occipital Lobe Input from Optic nerve Contains primary visual cortex The “eyes in the back of your head” Occipital Lobe Visual Lobe

Parietal Lobe Somatosensory Cortex Parietal Lobe Receives inputs from multiple senses Contains somatosensory cortex Deals with Skin Senses

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 Wernike’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.”

Language Areas of the Brain This research was done with a PET Scan

How We Read Out Loud

Brain Plasticity

2 Types of Plasticity 1.Structural Plasticity – Actual changing of the neuron or actually growing new neurons. Neurogenesis only occurs in the hippocampus 2.Functional Plasticity – When an area of the brain takes up a new function to replace a damaged area of the brain.

Examples of Plasticity If a body part is amputated, the surrounding neurons in the somatosensory cortex rewire themselves to other areas in the body. Example: The hand is between the face and are regions on the sensory cortex thus when stroking the face of someone whose hand was amputated, the person felt the sensation not only on their face but also on their nonexistent “phantom” fingers. A 5-year old boy who had severe seizures in his left hemisphere required the removal of the entire hemisphere. What was the result? While he is paralyzed on his right side he grew up to have above average intelligence, completed college and grad school and is now a business executive.

More Examples of Plasticity Newborn ferrets had the optic nerve of their brains rewired to take visual information into their auditory cortex. Result? It could see light in its auditory cortex. The sense of touch invades the part of the brain normally used for sight in blind people.

Brain Plasticity Brain Plasticity Can the brain rewire itself if you lose your vision? 7:03 minute clip Click below to view video What happens when you’re born without a portion of your brain? See video from class on hydrocephalic

More on Phantom Limbs Mirror Therapy to help with Phantom limb pain. See video HERE for explanation (5 min).HERE

Can a person’s environment affect their brain development? YES! An enriched environment = more neural connections in the brain. Click on video box to see how London Cab Drivers rewire their brain

Methods to Study the Brain

The Brain How do we learn about the brain & its functions?

Tools of discovery 1. Clinical observation (case study) - Phineas Gage – The Story of Phineas Gage (An Reenactment) – Module 25 of The Brain DVD (12:00)

The Brain Tools of discovery 2. Manipulating the brain a. Lesions – purposely destroying a part of the brain and observing the results. b. Brain Stimulation

The Brain Tools of discovery 3. Electroencephalogram (EEG) – shows the brain’s electrical activity.

The Brain Tools of discovery 4. Three Major Imaging Techniques CT Scan PET Scan MRI

Brain Imaging: 3 Types Imaging of the human brain allows us to look inside the brain without surgical intrusion. CT Scan CT (computed tomography) scanning is a much-improved version of x-ray imaging. A CT scan takes a series of cross-sectional photographs, which are then put together to form a three- dimensional image.

PET PET (positron emission tomography) scans reveal the activity of different areas of the brain by showing consumption of radioactive glucose (active neurons use more glucose) as the subject performs various mental activities.

MRI In MRI (magnetic resonance imaging), spinning atoms within the brain are aligned in a strong magnetic field. A brief pulse of radio waves disorients the aligned atoms, and the signals released as the atoms realign are processed to form images.

Two Types of MRI: Structural MRI Shows structures within the brain Click below to view an example Functional MRI Show functioning of different structures in the brain Click below to view an example