7.9

• The projections of the gustatory system are primarily ipsilateral
• The primary gustatory cortex, like primary olfactory cortex, is chemotopically organized.
• inability to smell

  Anosmia
• Less complete deficits in olfaction have been linked to a wide variety of neurological disorders including Alzheimer’s disease, Down syndrome, epilepsy, multiple sclerosis, Korsakoff’s syndrome, and Parkinson’s disease
• inability to taste

  Ageusia
• Why is ageusia rare?

  Because sensory signals from the mouth are carried via three separate pathways.
• the outcome of perception

  Percept
• True or False, our prior knowledge about the temporal order of sensory events also affects our perception.

  True
• From moment to moment, our brain is making decisions about what we should perceive, and those decisions are based on prior experiences and current incoming sensory information.
• Products of perception when there is an absence of sensory input:

  Phantom percepts
• Amputees perceive the presence of their missing limb long after it has been lost to injury or amputation.

  Phantom Limbs
• Those with this syndrome experience rich and complex hallucinations. The characteristics of the phantom percepts in this syndrome seem to be dependent on the person’s experience.

  Charles Bonnet Syndrome
• There is mounting evidence that such decisions are mediated by several areas in the brain, including the dorsolateral prefrontal cortex and the posterior parietal cortex.
• Those brain structures involved in action decision making are the same as those implicated in perceptual decision making.
• The question "How does the brain combine individual sensory attributes to produce integrated perceptions?" is called the binding problem.
• Two possible solutions to the binding problem:

  1. There is a single area of the cortex at the top of the sensory hierarchy that receives signals from all other areas of the various sensory systems.
  2. There is no single area responsible for putting together perceptions.
• A single area of the cortex at the top of the sensory hierarchy that receives signals from all other areas of the various sensory systems and puts them together to form a percept.

  claustrum
• 2 Characteristics of Selective Attention

  1. Improves the perception of the stimuli that are its focus
  2. Interferes with the perception of the stimuli that are not its focus
• Attention can be focused in two different ways:

  1. Endogenous attention
  2. Exogenous attention
• internal cognitive processes

  top-down (from higher to lower levels) neural mechanisms

  endogenous attention