Chapter 57 Cerebral Cortex, Intellectual Functions of the Brain, Learning, and Memory PDF

UNIT XI Chapter 57: Cerebral Cortex, Intellectual Functions of the Brain, Learning, and Memory Slides by David J. Dzielak, Ph.D Copyright © 2011 by Saunders, an imprint of...

UNIT XI Chapter 57: Cerebral Cortex, Intellectual Functions of the Brain, Learning, and Memory Slides by David J. Dzielak, Ph.D Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Physiologic Anatomy of Cerebral Cortex each area of the cortex is connected to a specific part of the thalamus. when thalamic connection is lost cortical function stops. all sensory pathways pass through the thalamus with the exception of the olfactory tract. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Thalamic Connections to the Cortex Figure 57-2 Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Physiological Anatomy of the Cerebral Cortex Figure 57-5 Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Dominant and Non-Dominant Hemisphere Wernicke’s area more developed in one hemisphere, responsible for verbal symbolism and related intelligence. 95% of population has a left dominant hemisphere. Wernicke’s area can be as much as 50% larger in the dominant hemisphere. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Dominant and Non-Dominant Hemisphere (Cont.) damage to dominant Wernicke’s area leads to dementia. non-dominant side related to other forms of sensory intelligence (music, sensory feelings). Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Intellectual Functions of the Prefrontal Association Area responsible for calling forth stored information and using it to obtain a goal. responsible for concerted thinking in a logical sequence. – damage causes an inability to keep tract of simultaneous bits of information, easily distracted. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Intellectual Functions of the Prefrontal Association Area (Cont.) elaboration of thought. – prognosticate, plan, consider consequences of motor actions before they are performed. correlate widely divergent information, control one’s activities. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Function of the Brain in Communication “For millions of years mankind lived just like the animals. Then something happened which unleashed the power of our imagination we learned to talk.” Pink Floyd Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Pathways for Auditory Communication 5. activation of motor 6. transmission of signals to motor programs in Broca’s area for cortex to control speech muscles 4. transmission via the control of word formation arcuate fasciculus to Broca’s area 3. formation of the word that expresses a particular thought 2. interpretation of the word and the thought that the word expresses in Wernicke’s area 1. primary auditory area recognition of the sound as a word Figure 57-8 modified Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Pathways for Visual Communication 5. transmission of signals to motor cortex to control speech muscles 4. then to Broca’s area for motor formation of the word 3. visual input reaches full level of interpretation in Wernicke’s area 2. processing of the visual information in the parietal- temporal-occipital association cortex, the angular gyrus region 1. receive the visual input in primary visual area Figure 57-8 modified Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Sensory Aspects of Communication Wernicke's aphasia destruction of the visual and auditory association areas results in an inability to understand the written or spoken word. Figure 57-7 Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Motor Aspects of Communication speech involves two things – formation in the mind of thoughts to be expressed and the choice of words. – motor control of vocalization and the act of vocalization formation of word, thought and choice of words is function of Wernicke’s area. Broca’s area controls the motor coordination required for speech. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Function of the Corpus Callosum connects the two hemispheres and allows transfer of information. interruption of these fibers can lead to bizarre types of anomalies. – dominant hemisphere understands spoken word. – non dominant hemisphere understands written word and can elicit motor response without dominant side knowing why response was performed. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Thoughts and Memory neural mechanism for thought is not known. most likely a specific pattern of simultaneous neural activity in many brain areas. destruction of cerebral cortex does not prevent one from thinking. – however, depth of thought and level of awareness may be less. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Memory change in the capability of synaptic transmission from neuron to neuron as a result of prior stimulation. memory trace is a specific pattern or pathway of signal transmission. once established they can be activated by the thinking mind to reproduce the pattern and thus the memory. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  3 Types of Memory immediate memory – lasts for seconds or minutes short-term memory – lasts for days to weeks long-term memory – lasts for years or for a lifetime Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Mechanism of Memory immediate memory may result from synaptic potentiation through the accumulation of calcium in the presynaptic membrane. – would promote neurotransmitter release. short-term memory may result from a temporary physical or chemical change in the pre- or postsynaptic membrane. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Cellular Basis for Memory repetitive stimulation causes a progressive decline in sensitivity called habituation. results from progressive decline in the number of active calcium channels. less calcium entry less transmitter released. stimulation of facilitator terminal prevents habituation. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Molecular basis for memory Transmitter activates G protein which in turn activates adenylate cyclase resulting in an increase in cAMP cAMP activates a protein kinase that phosphorylates a component of the K+ channel blocking its activity. Figure 57-9 this prolongs the action potential which increases transmitter release. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Long-Term Memory results from a structural change in the synapse. increase in the area for vesicular release therefore, more transmitter is released. during periods of inactivity the area decreases in size. enlargement of the release site area results from synthesis of release site proteins. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Consolidation of Memory converting immediate into short and long-term memory. results from chemical, physical and anatomical changes in the synapse. requires time. interruption of the process by electrical shock or by anesthesia will prevent memory development. rehearsal enhances consolidation. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Brain centers for memory hippocampus is critical for long-term memory. damage causes inability to form new verbal or symbolic long-term memory anterograde amnesia. hippocampus is involved in determining which sensory experiences are important and which do not require attention. Kandel, Schwartz and Jessell 4th edition 2000, McGraw Hill fig 62-5a Copyright © 2011 by Saunders, an imprint of Elsevier Inc.  Brain Centers and Memory thalamic structures are important for recalling memories. damage to thalamus causes retrograde amnesia or the inability to recall stored experiences. thalamus scans the cortex for the area and the circuit for the stored memory. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.