Chapter 3Biological Foundations [page 90
The Association Cortex
Large areas that are not associated with sensory or motor functions.
Involved in mental processes such as language, thought, memory and perception.
Found in all lobes of cerebral cortex.
Electrically stimulating them doesn’t affect sensory or motor responses.
Damages to association cortex causes disruption/loss of speech, understanding, thinking, problem
Constitutes for 75% of human cerebral cortex.
Responsible for linking information together.
Damages may cause agnosia, inability to identify familiar objects.
The Motor Cortex
Controls activity of skeletal muscles.
Each hemisphere governs movements on opposite side of body.
Somatic Sensory Cortex
Receives sensory input that gives rise to our sensations of heat, touch, cold, and senses of balance and
Auditory areas are in both hemispheres, so loss of one temporal lobe has little effect on hearing.
Each eye sends input to both occipital lobes in both hemispheres.
Speech Comprehension and Production
Wernicke’s areas in the temporal lobe ▯involved in language comprehension
Broca’s area in the frontal lobe ▯ speech production. Formulates a speech response and stimulates
Motor cortex stimulates muscles that produce speech.
Wernicke’s areas process incoming speech and comprehend it.
The Frontal Lobes: The Human Difference.
Damages to these lobes result in:
- A loss of ability to plan and carry out a sequence of actions and judge series of events
- Attitudes of apathy and lack of concern. Don’t care about anything
High activity in frontal lobes: feelings of happiness, sadness, disgust.
Prefrontal cortex is responsible for:
1. Executive functions
2. Mental abilities involving goal setting, judgment, strategic planning, impulse control, directing
behaviour to adapt
Prefrontal cortex disorders ▯people are oblivious to future consequences of their actions, impulsive
Prefrontal cortex is involved in behavioural control, aggression, and criminal behaviour Hemispheric Lateralization: Left and Right Brains
Neural bridge that links two hemispheres for them to function as one.
Greater localization of a function in one hemisphere or the other
Cerebral cortex: sheet of grey (unmyeliated) cells that for outermost layer of human brain
Aphasia: when Broca’s or Wernicke’s speech areas are damaged, there is inability to communicate
Plasticity in the Brain: Role of Experience and the Recovery of Function
Neural Plasticity: the ability of neurons to change in structure and function du▯ arly experience
and recovery after injury
Lecture 8 [02.10.12]
Lateralization and Split Brain
Next time: Genetics, do practice exams, do discussion 1! Look at course content for lectures
Scan: page 109116
How are the cortical areas organized?
What happens if these areas are damaged?
Is there a separate consciousness in each hemisphere?
o Epilepsy: separated corpus callosum
o Cortex is bilaterally symmetrical (there are 2 sides
o Graded potentials add together, time is 1 to 2 millisec for action potential to hit
o Right hemisphere is more emotional, left hemisphere is more logical
o Drug enters the bloodstream, in your nose you have tiny blood vessel that absorb cocaine
effectively, it has to pass blood brood barrier (soluble, fatty molecules can easily get through)
o Neuron a and b synapse with neuron c. you are measuring the electrical activity in neuron c. when
neuron a fires, an AP is generated in neuron c. But when A and B are stimulated, there is no AP
observed in C. How can you explain this? Neuron B generates an IPSP (IPSP=EPSP they cancel
each other out)
o Motor projection area, somatosensory area, visual area, auditory area
1. Topographic Representation ▯mapping of motor cortex (upside down)
2. Contralateral control ▯the left hemisphere control the right, right controls left hemisphere 3. Functional Assignment of space m ▯ ore functionally important area (in the face) is, the more
cortical area is devoted to it; Certain cortex regions have more brain tissue and more processing
o Inside central fissure: plotting areas low in the body (toes, ankle), as you move away from the
brain, you move up body parts closer to the brain
How do we get this informatio