Feb 27, 2021
PSY 340 Brain and Behavior
Class 11: Cerebral Cortex [Outline]
• "gray matter" consists mostly of the bodies of neurons
• "white matter" consists mostly of axons from neurons
Each of the two cerebral hemispheres communicates with the other via several bundles of axons. The largest is the corpus callosum (see diagram on the right and left below). A second, smaller connection is the anterior commissure (see diagram on the left below).
Organization of the Cerebral Cortex
Laminae: Six Layers or laminae (singular = lamina)
- Layer IV receives sensory data from thalamus
- Layer V sends out motor instructions to the spinal cord
Central Sulcus: A sulcus (sulci, pl.) is a fissure, groove, or depression on the surface of the cortex. These sulci normally separate ridges or protrusions of cortical tissue called gyri (gyrus, singular).
The central sulcus separates the Frontal from the Parietal Lobe of the brain. Anterior to (in front of) the Central Sulcus lies the Precentral Gyrus. We have already seen this area under the label of the brain's "Motor Strip." Posterior to (in back of) the central sulcus lies the Postcentral Gyrus. We have already seen this area under the label of the brain's "Somatosensory Strip."
The Lobes of the Cerebral Cortex
- Vision. At the very posterior of the lobe lies the "Primary Visual Cortex" (labeled as "17" and "V1" in the diagram).
- Destruction to this area causes cortical blindness
- Projections to temporal and parietal areas
- Body Sensations: The Postcentral Gyrus ("Somatosensory Strip")
- Visuo-spatial Processing and Sensory Integration
- The parietal lobe maintains representations of the body's and of the head's position in space.
- Analysis of object positions in space and visual motion
- Hearing: primary auditory cortex
- the recognition of faces and objects (visual information sent from the occipital lobe)
- Other emotional and motivational behaviors
- Klüver-Bucy Syndrome
- putting many types of objects in the mouth,
- emotional placidity,
- hyper/inappropriate sexual advances, and
- distractability caused by small objects.
- Heinrich Klüver (1897-1979) and Paul Bucy, experimented on monkeys who were described as "psychically blind"
Prefrontal Cortex: Executive Control. integrate a large amount of data involving "executive" planning and judgment, emotional modulation, and other tasks.
- "Motor Strip" or Precentral Gyrus
Involved with working memory: short-term information (rather than long-term factual data) & responding to delayed-response tasks (needing to respond to what is remembered after a short delay)
Control of behavior that depends upon context or setting. Damage shows itself in impulsivity or inappropriate responses. For example, do you look through the desk drawers in someone else's home? What difference does it make to your behavior if you are in a sports arena or your local church?
From the late-1930s to the mid-1950s, physicians performed prefrontal lobotomies.
Developed in Europe, but pioneered in the U.S. by a physician, Dr. Walter Freeman. It was used with about 40,000 patients
Putting It Together: The Binding Problem
Which one of these pictures is easier to view as a whole?
V. Ramachandran: Mirror Box Therapy