Chapter 58 cerebral cortex, intellectual functions
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The document summarizes key aspects of the cerebral cortex, its functions, and memory. It discusses that the cerebral cortex is the largest part of the nervous system but our understanding is limited. It has over 100 billion neurons organized into six layers that perform different functions like receiving sensory input and sending output signals. Specific cortical areas support motor control, sensory processing, and higher cognitive functions through association areas. Memory formation involves changing synaptic transmission through sensitization that strengthens pathways for positive memories and habituation that weakens pathways for unimportant information.
Chapter 58 cerebral cortex, intellectual functions
- 1. Cerebral Cortex, Intellectual Functions of the Brain, Learning, and Memory Prepared by : Dr. dr. I Putu Adiartha Griadhi, M.Fis Medical School of Udayana University, Denpasar - Indonesia Reference : Guyton and Hall, Textbook of Medical Physiology, 13th edition, 2016.
- 2. PHYSIOLOGICAL ANATOMY OF THE CEREBRAL CORTEX • The largest portion of the nervous system but we know the least about it • The functional part of the cerebral cortex : a thin layer (2 – 5 mm) of neurons, about one quarter m2. • The total cerebral cortex contains about 100 billion neurons. • Most of the neurons are of three types: • Granular (stellate) – IN (excitatory & inhibitory) • Fusiform -- output fibers • Pyramidal -- output fibers (spinal cord & subcortical association fiber)
- 3. PHYSIOLOGICAL ANATOMY OF THE CEREBRAL CORTEX • Incoming specific sensory signals from the body terminate in cortical layer IV • Output signals leave the cortex through neurons located in layers V and VI • the very large fibers to the brain stem and cord arise generally in layer V; • and the tremendous numbers of fibers to the thalamus arise in layer VI. • Layers I, II, and III perform most of the intracortical association functions • Important relation (bidirectional) between the cerebral cortex and the thalamus (58-2) -- thalamocortical system
- 4. FUNCTIONS OF SPECIFIC CORTICAL AREAS Motor Areas • Primary motor areas: Have direct connections with specific muscles for causing discrete muscle movements Sensory Areas • Primary sensory areas: Detect specific sensations (visual, auditory, or somatic)
- 5. FUNCTIONS OF SPECIFIC CORTICAL AREAS ASSOCIATION AREAS • Association areas because they receive and analyze signals from multiple regions of the cortex. The most importat association areas are 1. Parieto-occipitotemporal association area 2. Prefrontal association area 3. Limbic association area Limbic association area
- 6. FUNCTIONS OF SPECIFIC CORTICAL AREAS Parieto-occipitotemporal association area • Analysis of the Spatial Coordinates of the Body : Provides continuous analysis of the spatial coordinates of all parts of the body as well as of the surroundings of this body • Area for Language Comprehension : The most important region for higher intellectual function because almost all such intellectual functions are language based. • Area for Initial Processing of Visual Language – Reading : Make meaning out of the visually perceived words • Area for Naming Objects Provides a high level of interpretative meaning for signals from all the surrounding sensory areas
- 7. FUNCTIONS OF SPECIFIC CORTICAL AREAS Prefrontal association area • Important for elaboration of thoughts and is also essential to carrying out thoughts processes in the mind • Broca’s Area: Provides the neural circuity for word formation and work with close association with Wernicke’s area Limbic Association Area • It is concerned primarily with behavior, emotions, and motivations Provides a high level of interpretative meaning for signals from all the surrounding sensory areas
- 8. FUNCTIONS OF SPECIFIC CORTICAL AREAS WERNICKE’S AREA -- A GENERAL INTERPRETATIVE AREA • Highly developed in the dominant side • It plays the greatest single role in comprehension levels of brain functions that we call intelligence • After damage in Wernicke’s area the person turn be unable to arrange words into a coherent thought • Angular Gyrus : Lying behind Wernicke’s area and fusing posteriorly into visual areas of the occipital lobe - -Dyslexia
- 9. FUNCTIONS OF SPECIFIC CORTICAL AREAS CONCEPT OF THE DOMINANT HEMISPHERE • The general interpretative functions of Wernicke’s area and the angular gyrus, as well as the functions of the speech and motor control areas, are usually much more highly developed in one cerebral hemisphere – Dominant Hemisphere • 95% of all people – left dominant hemisphere • Corpus Callosum – Communication between the two hemispheres
- 10. FUNCTIONS OF SPECIFIC CORTICAL AREAS FUNCTIONS OF THE PARIETO- OCCIPITOTEMPORAL CORTEX IN THE NONDOMINANT HEMISPHERE • Nondominant hemisphere may be especially important for understanding and interpreting music, nonverbal visual experiences, the significance of body language, and intonation of the people’s voice
- 12. THOUGHTS, CONSCIOUSNESS, AND MEMORY Thoughts • A thought results from a ‘pattern’ of stimulation of many parts of the nervous system at the same time, probably involving most importantly the cerebral cortex, thalamus, limbic system, and upper reticular Consciousness • Can be describe as our continuing stream of awareness of either our surroundings or our sequencial thoughts formation of the brain stem
- 13. THOUGHTS, CONSCIOUSNESS, AND MEMORY Memory • Changing the basic sensitivity of synaptic transmission The greater share of our memories are negative • Positive and Negative Memory—“Sensitization” or “Habituation” of Synaptic Transmission • Positive memory – Storing memory – Facilitation of the synaptic pathways = memory sensitization • Negative memory: Our brain is inundated with sensory information from all our senses – The brain has the ability to ignore information – Result from inhibition of the synaptic pathways – Effect called Habituation
- 14. Habituation • If our minds attempted to remember all this information, the memory capacity of the brain would be rapidly exceeded. • When the sensory terminal is stimulated repeatedly but without stimulation of the facilitator terminal, signal transmission at first is great, but it becomes less and less intense with repeated stimulation until transmission almost ceases. • This phenomenon is habituation. • It is a type of negative memory that causes the neuronal circuit to lose its response to repeated events that are insignificant. One terminal, which is from a sensory input neuron, terminates directly on the surface of the neuron that is to be stimulated and is called the sensory terminal. The other terminal, a presynaptic ending that lies on the surface of the sensory terminal, is called the facilitator terminal
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