Gero 310 F'09 neuro 2

Gero 310 F'09 neuro 2 - Age changes in the central nervous...

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Age changes in the Age changes in the central nervous system (CNS) central nervous system (CNS) 1) 1) spinal cord spinal cord - loss of motor neurons w/ age - loss of motor neurons w/ age 2) brain • reduced overall size, weight - smaller by 0.1-0.2% per year ages 30-50 - escalates to 0.3-0.5% per year in aged • enlarged ventricles • shrinking of gyri, widening of sulci ** all evidence of neuron cell loss - does this occur?? - are dendrites lost? - what are the functional correlates?? • glia become reactive
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Burke SN and Barnes CA (2006) Nat. Rev. Neuro. 7: 30–40 The myth of brain aging - for many years it was thought that neuron number and dendritic branching were significantly reduced during normal aging - however, neuron number is largely retained - also, dendritic branching is largely retained - however there are some regional age-related losses - e.g., prefrontal cortex shows loss in dendrites in aged
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- much emphasis on the hippocampus, since many cognitive impairments in aging are associated with hippocampal function Jessberger & Gage (2008) Psychology and Aging - however, aged hippocampus shows no significant loss in neuron number, dendritic complexity, spine number across subfields - evidence for reduced axo-dendritic PF/DG synapses - but structural changes in hippocampus with age rather modest Markham et al. (2005) Hippocampus
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• aging is associated with impairments in specific types of memory - termed ‘age-associated memory impairment’ - can be detected by the 5th decade • some skills relatively unaffected , for example, procedural memory - e.g., how to write, drive a car, make a cup of tea * aged humans exhibit deficits in memory requiring hippocampus 1. explicit (aka declarative) memory 2. episodic memory 3. visuospatial memory (e.g., spatial navigation) 4. trace eyeblink conditioning (involves cerebellum) • as with the rest of the body, expect age-associated impairments in structure and function * aged humans also show deficits in tasks involving prefrontal cortex - working memory (also requires hippocampus) - executive function (e.g., delayed non-matching to sample)
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Age-related impairment on spatial memory task Age-related impairment on spatial memory task • rat groups: young = 6 mo middle-aged = 12 senescent = 23-28 mo • task: Morris water maze - spatial memory, navigation task - visual cues - find hidden platform in opaque water bath * aged rats exhibit deficits in acquisition of a spatial task - modest but significant impairment
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Flicker et al. (1984) Age-related impairment on visuospatial recall task Age-related impairment on visuospatial recall task • human groups: young = 18-42 y aged = 57-85 aged-dem = 57-85 with mild dementia * aged humans exhibit impaired performance with delay, but perform perfectly without delay - deficits most apparent as task difficulty increases • task (hippocampal-dependent): - recall highlighted room on a computer image showing house with 25 rooms - delay between highlighting and recall of 0-2 min
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This note was uploaded on 01/16/2011 for the course GERO 310 taught by Professor Davies during the Fall '09 term at USC.

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Gero 310 F'09 neuro 2 - Age changes in the central nervous...

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