Psych11 bloa - localisation of brain function- exterior structure

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Psych11 bloa - localisation of brain function- exterior structure

  1. 1. The brain Localisation of brain
  2. 2. The role of the cerebral cortex  The cerebral cortex is the part of the brain that is responsible for such higher mental processes as thinking, perceiving and remembering.
  3. 3. Lobes of the cerebral cortex  The four lobes are:  The frontal lobe  The parietal lobe  The occipital lobe  The temporal lobe
  4. 4. So What Makes Up A Lobe?  Primary area- Each lobe has a primary area, which may be motor or sensory. These areas are involved in receiving sensory messages or sending movement messages to muscles.  Association area- Each lobe also has association areas, which are involved in higher order brain functions such as learning, memory, thought and language. They receive information from primary sensory areas and from the lower parts of the brain. Association areas make up 75% of the cerebral cortex.
  5. 5. The Frontal Lobe  The Frontal lobe is the largest lobe. It is located at the front of the cerebral cortex.  It contains the motor cortex. The motor cortex is a narrow strip, located at the back of the frontal lobe, in front of the central fissure. The motor cortex controls virtually all INTENTIONAL bodily actions.
  6. 6. Structures Within the Frontal Lobe  Premotor area- Located immediately in front of the primary motor area, and is one of the secondary areas of the frontal lobe. The premotor area selects movements in response to external cues.
  7. 7. Structures Within the Frontal Lobe  Supplementary motor areas- Located in front of the primary motor area next to the premotor area. The supplementary area selects movements in response to internal events.
  8. 8. The Association Area of the Frontal Lobe  Prefrontal cortex- The association area- The prefrontal cortex refers to all of the cortical tissue that lies in front of the premotor cortex of the frontal lobes. It receives sensory input from other cortical lobes. This means that sensory information is involved in the cognitive processes of planning, selecting and carrying out behaviours.
  9. 9. An Example of the Association Area in Action  E.g. The process of passing a ball to a teammate during a game of netball not only requires the selection and execution of the appropriate movements, but also knowledge about your environment. All the planning necessary for this behaviour relies on information received from external circumstances.
  10. 10. Association Area  Another source that may affect the planning of movements comes from internal sources, such as memory and emotion. The frontal lobes are believed to be involved in memory formation, personality and the control and expression of emotions, although our understanding of this process is limited.  The prefrontal lobe is capable of integrating information from both internal and external sources in order to plan behaviour.
  11. 11. Broca’s Area  Broca’s area is located in the LEFT Frontal lobe.  It is located close to the motor cortex, near the areas responsible for the muscles of the face, tongue, jaw and throat.
  12. 12. Broca’s Area  It is named after the French neurologist Pierre Broca (1824- 1880), as he is considered the person who first identified its function.  Broca treated a man named ‘Tan’. Tan had experienced a number of strokes and as a result his verbal communication was limited to ‘tan- tan’, however, he could comprehend what others said to him. After Tan passed away Broca examined his brain.  Broca conducted examined the brains of other clients (after they died!) who displayed similar symptoms to Tan all had damage to this part of the brain.
  13. 13. Broca’s Area  Broca’s area is responsible for/ plays a part in:  Coordinating messages to the parts of the body that allow you to produce speech in a clear and fluent manner.  Interacting with areas of the cerebral cortex involved in deriving meaning from language, sentence structure and grammar.
  14. 14. Broca’s Aphasia  Damage to Broca’s area leads to a condition called Broca’s aphasia, which is characterised by difficulties with speech production but generally not with speech comprehension. The language of Broca’s aphasia patients provides only the content- the nouns, adjectives, verbs and adverbs.  Patients have difficulty using functional words that provide grammatical meaning, such as on, and, at and about.  Other language abilities that aren’t dependent on speech such as reading and writing, do not seem affected by damage to Broca’s area.  Evidence also suggests that speech comprehension can be impaired when the usual order of words has been changed.
  15. 15. Phineas Gage  http://www.pubmedcentral.nih.gov/articlerender.fcg  Summarise this famous case study and what researchers were able to learn from it.  Write some of the strengths and weaknesses of case studies as a research method.
  16. 16. Parietal Lobe  Extending towards the back of the brain is the parietal lobe. The parietal lobe is involved in the functions such as the sense of touch, detection of movement, the location of objects in the surrounding environment and the sensations felt by the body as it moves. As with the frontal lobe, the parietal lobe has primary, secondary and association areas.
  17. 17. Primary Somatosensory Cortex  Primary somatosensory cortex- Is located at the front of the parietal lobe. It receives information about what the body is touching and feeling. It is organised in a contralateral manner. The sensory input comes from the tracts of neurons that extend from the spinal cord up through the hindbrain and midbrain.  The area of cortex relates to the sensitivity of the body part.
  18. 18. Sensitivities of the Primary Somatosensory Cortex
  19. 19. Secondary and Association Areas  Posterior parietal cortex  Input from other areas of the brain is integrated in this secondary and association area to inform sensational experiences.  The other functions include visual attention and spatial reasoning.
  20. 20. Occipital Lobe  The Occipital lobe is located behind the Parietal lobe, towards the back of the cortex. It is the smallest of the four lobes.
  21. 21. Primary Visual Cortex  The primary visual cortex is responsible for the initial processing of visual information by the brain. The primary visual cortex receives information via a pathway of neurons that extends from a part of the brain known as the thalamus, which transmits information directly from the optic nerve at the back of the eye.
  22. 22. Primary Visual Cortex  Information received from the visual cortex is organised in a contralateral manner. The left primary visual cortex receives information from the left visual field, not the left eye and vice versa.  The primary visual area does not devote equal amounts of the cortex to all parts of the visual field. Most of the cortex is devoted to stimuli in the centre of the visual field than to the peripheral aspects of the field.
  23. 23. Contralateral Organisation
  24. 24. Association Areas  To see an object as a whole, rather than its components the visual information needs to be further processed in the secondary and association areas of the occipital lobe.
  25. 25. Temporal Lobe  The temporal lobe contains the primary auditory cortex. The primary auditory cortex is involved with the sense of hearing. The primary auditory cortex is organised in bands according to the frequency of sounds to which they respond. Bands at the front respond to low frequency sounds, the bands at the back to high frequency sounds.
  26. 26. Primary Auditory Cortex  The area of the cortex is disproportionate, with middle frequencies having a greater amount of cortex space dedicated to them. This is because they are the frequencies generally used in speech.
  27. 27. Secondary Areas  The several areas of secondary auditory cortex surround the primary auditory cortex. How these areas function is not fully understood, but are believed to be activated in response to more complex sounds. May be involved in the detection of pitch, change in frequency, identifying the location of sound in the environment.
  28. 28. Association Area  The association areas is significant in size. The area towards the back of the temporal lobe, near the occipital lobe is thought to be involved in the labelling/naming of visual stimuli and coupling visual and auditory stimuli. Other areas are involved in memory formation and emotions. The closeness of memory and emotion areas may explain the link between recalling memories and emotions The temporal lobe appears to have a significant role in memory, including receiving, processing and storing memories. Different types of memory are involved, they are: semantic, procedural and episodic memories.
  29. 29. Wernicke’s Area  The primary function of Wernicke’s area is to interpret sounds, primarily the sound of human speech. It is located near the auditory cortex and emphasising the link between hearing and language. It is located in the left hemisphere. It seems to play a central role in associating the sound of a word with its meaning. It could also be where memories for the sounds that make up words are stored. Wernicke’s area may also control other areas involved in speech production, such as Broca’s area.
  30. 30. Wernicke’s Aphasia  When someone has lesions in Wernicke’s area they are said to suffer Wernicke’s aphasia. Speech is still fluent, but the content is disrupted. They tend to make sound substitutions or word substitutions. They typically have trouble with understanding information the read or see.  They express a “word salad”
  31. 31. Cerebellum  The Cerebellum is part of the hindbrain. It is important for balance and coordination.  More recent research also indicates that it also plays a role in attention and timing (including sensory timing).  People with damage to the cerebellum have trouble shifting their attention between auditory and visual stimuli.  An example of how timing may be affected is that they may have trouble distinguishing the pace of two rhythms (i.e. Which one is faster).

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