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Sensation and perception

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  • 1. Sensation and Perception By: SHJ
  • 2. Sensation  Detection of a stimulus on the receptor cells of a sensory organ, leading to a series of biochemical and neurological responses  The first stage in the function of the senses  Comes from the environment and gets transformed into neural signals that get interpreted in the brain through a process called Transduction  Transduction is regarded as the bridge that connects sensation and perception together
  • 3. Perception -The mental process that represents the awareness of the real-world causes of a given stimulus -Creates useful information of the surrounding environment (1)
  • 4. Different types of receptors Chemoreceptors Photoreceptors Mechanoreceptors Thermoreceptors
  • 5. Chemoreceptors Detects chemical stimuli and converts the signals into electrical action potentials Distance chemoreceptors are involved in receiving stimuli in the olfactory system Direct chemoreceptors can be found in taste buds and aortic bodies that measure oxygen concentrations (2)
  • 6. Chemoreceptors
  • 7. Photoreceptors  Converts light signals into a membrane potential  Three types of photoreceptors: cones, rods, and ganglion cells  Cones respond to colors of different wavelengths, such as short (blue), medium (green), and long (yellow/red)  Rods respond to light intensity, such as vision adjustment in response to a dark room (3)  Ganglion cells can be found in the adrenal medulla, but also in the retina as part of the sympathetic response (4)
  • 8. Photoreceptors
  • 9. Photoreceptors
  • 10. Mechanoreceptors  In response to mechanical forces, such as pressure and distortion  Hair cells in the auditory and vestibular systems  Majority of mechanoreceptors can be found on the skin and can be grouped into four subcategories: Slowly Adapting type 1, Slowly Adapting type 2, Rapidly Adapting, and Pacinian Receptors  Slowly Adapting type 1-responds to form and roughness  Slowly Adapting type 2-responds to stretch  Rapidly Adapting-responds when a person slips  Pacinian Receptors-responds to high frequency vibration (5)
  • 11. Mechanoreceptors and thermoreceptors
  • 12. Thermoreceptors Responds to temperature variation Exact mechanism is unclear but recent mammal studies reveal two possibilities (6) Bulboid Corpuscle detects above body temperature Ruffini’s end organ detects below body temperature
  • 13. Sensory cortex  Multiple area of the brain at which senses are received for processing  Each of the five senses contains a primary and secondary cortex (7) Vision-visual cortex Hearing-auditory cortex Smell-primary olfactory cortex Taste-gustatory cortex Touch-somatosensory cortex
  • 14. Visual cortex  Often referred to as the primary visual cortex (V1) and can be found in the Brodman area 17, in the occipital lobe of the brain (8)  Primary relay station for visual input to one of two pathways: Dorsal stream and Ventral stream  Dorsal stream detects the location of the stimulus and how it’s presented (ex: on the ground and sitting with the tongue sticking out)  Ventral stream detects what the stimulus is exactly (ex: it’s a dog) (9)
  • 15. Visual cortex
  • 16. Auditory cortex Cochlea corresponds to the temporal lobe Consists of anterior transverse temporal area 41 and posterior transverse temporal area 42, also known as Brodmann areas 41 and 42 Both areas receive and process sound signals from the auditory receptors (10)
  • 17. Primary (blue) and secondary (red) auditory cortex
  • 18. Primary olfactory cortex  Located in the temporal lobe  Peripheral and central mechanisms of action are present  Peripheral-olfactory receptor neurons transmits a chemical signal along the nerve to the olfactory bulb at the end  Central-multiple nerve axons combine to form a glomeruli at the olfactory bulb, before being transferred to the primary olfactory cortex
  • 19. Olfactory and Gustatory cortex
  • 20. Gustatory cortex  Detects taste sensations  Contains anterior insula, which is part of the insular lobe, and the frontal operculum, which is part of the frontal lobe  Just like the olfactory cortex, the gustatory cortex also contains a peripheral and central mechanism  Receptors are located on the tongue, soft palate, pharynx, and esophagus. They receive the signals and transmit them to the primary sensory axons, which are then sent over to the nucleus of the solitary tract in the medulla, also known as the gustatory nucleus of the solitary tract complex.  The signal is then sent to the thalamus, followed by the gustatory cortex and other parts of the neocortex (11)  Receptor-primary sensory axons--gustatory nucleus of solitary tract complex--thalamus---gustatory cortex
  • 21. Somatosensory cortex  Located in the parietal lobe  Cortex can be divided into Brodmann areas 1, 2, 3  Brodmann 3 is the primary processing center, receiving most of the input from the thalamus and creating somatic sensations through electrical stimulation.  Areas 1 and 2 get most of their input from area 3
  • 22. Somatosensory cortex
  • 23. Loss of Sensation Either due to ineffective receptors, nerve damage, or cerebral impairment Vision loss Hearing loss Anosmia Ageusia Somatosensory loss
  • 24. Vision loss  Usually caused by varying degrees of damage, either resulting in total blindness or no adverse effect at all  Also can be caused by sensory failure  Opacities in the eye media alters the image despite normal photoreceptor cells (ex: glaucoma, diabetic retinopathy, and macular degeneration)  Optic nerve damage on the afferent pathways after transmission from those normal photoreceptor cells
  • 25. Hearing loss Also can vary from minimal to total hearing loss Can be caused by damage mechanoreceptors secondary to prolonged noise Cochlear and auditory nerve damage can also occur as a result of HIV and meningitis, respectively (12)
  • 26. Anosmia A loss of smell, due to damage to the olfactory receptor neurons Often due to nasal polyps or upper respiratory tract infections Also due to olfactory nerve damage, often from hypothyroidism or physical trauma. (7)
  • 27. Ageusia  Taste loss can also vary widely.  Damage to the lingual nerve, affecting signals from the front two-thirds of the tongue  Damage to the glossopharyngeal nerve (cranial nerve 9), affecting signals from the back third of the tongue  Damage may be due to neurological disorders, such as Bell’s palsy or multiple sclerosis  Damage can also come from infectious diseases such as meningoencephalopathy.  Other causes include a vitamin B deficiency, acidic/spicy foods, radiation, and/or tobacco use (13)
  • 28. Somatosensory loss  Insensitivity to touch stimuli and loss of motor stimulation.  Caused by damage to the spinal cord or other major nerve fiber, which can lead to a loss of both afferent and efferent signals to varying areas of the body.  Other types of somatosensory loss include hereditary sensory and autonomic neuropathy, which consists of ineffective afferent neurons with fully functioning efferent neurons; essentially, motor movement without somatosensation (14)
  • 29. References  (1) Gazzaninga, M., Heatherton, T., Halpern, D. & Heine, S. (2010). Psychological Science ( 3 ed.). New York: W.W. Norton & Company, Inc. p. 188  (2) Satir,P. & Christensen,S.T. (2008) Structure and function of mammalian cilia. in Histochemistry and Cell Biology, Vol 129:6  (3) “eye, human." Encyclopædia Britannica. Encyclopædia Britannica Ultimate Reference Suite. Chicago: Encyclopædia Britannica, 2010.  (4) Foster, R. G.; Provencio, I.; Hudson, D.; Fiske, S.; Grip, W.; Menaker, M. (1991). "Circadian photoreception in the retinally degenerate mouse (rd/rd)". Journal of Comparative Physiology A 169. doi:10.1007/BF00198171  (5) Winter, R., Harrar, V., Gozdzik, M., & Harris, L. R. (2008). The relative timing of active and passive touch. [Proceedings Paper]. Brain Research, 1242, 54-58
  • 30. References  (6) Krantz, John. Experiencing Sensation and Perception. Pearson Education, Limited, 2009. p. 12.3  (7) Brynie, F.H. (2009). Brain Sense: The Science of the Senses and How We Process the World Around Us. American Management Association  (8) McKeeff, T. J., & Tong, F. (2007). The timing of perceptual decisions for ambiguous face stimuli in the human ventral visual cortex. [Article]. Cerebral Cortex, 17(3), 669-678  (9) Hickey, C., Chelazzi, L., & Theeuwes, J. (2010). Reward Changes Salience in Human Vision via the Anterior Cingulate. [Article]. Journal of Neuroscience, 30(33), 11096-11103  (10) Purves, Dale et al. 2008. Neuroscience. Second Edition. Sinauer Associates Inc. Sunderland, MA  (11) ^ Purves, Dale et al. 2008. Neuroscience. Second Edition. Sinauer Associates Inc. Sunderland, MA.
  • 31. References  (12) ^ Bizley, J. K., & Walker, K. M. M. (2010). Sensitivity and Selectivity of Neurons in Auditory Cortex to the Pitch,Timbre, and Location of Sounds. [Review]. Neuroscientist, 16(4), 453-469. doi:10.1177/1073858410371009  (13) ^ Macaluso, E. (2010). Orienting of spatial attention and the interplay between the senses. [Review]. Cortex, 46(3), 282-297. doi:10.1016/j.cortex.2009.05.010  (14) ^ Li, X. (1976). Acute Central Cord Syndrome Injury Mechanisms and Stress Features. Spine, 35, E955-E964  Wikipedia article on sensation (psychology)
  • 32. Photos http://science.howstuffworks.com/life/human-biology/taste1.htm http://people.eku.edu/ritchisong/301notes6.htm http://www.webexhibits.org/causesofcolor/1G.html http://www.bem.fi/book/28/28.htm http://bdml.stanford.edu/twiki/bin/view/Haptics/VibrationOrForce.html http://thebrain.mcgill.ca/flash/i/i_02/i_02_cr/i_02_cr_vis/i_02_cr_vis.h tml http://en.m.wikipedia.org/wiki/File:Auditory_Cortex_Frequency_Mappin g.svg http://scientopia.org/blogs/scicurious/2011/05/11/science-101-cranial- nerve-i-the-olfactory-nerve/ http://droualb.faculty.mjc.edu/Course%20Materials/Physiology%20101 /Chapter%20Notes/Fall%202011/chapter_10%20Fall%202011.htm