Tactile

Tactile

• Pain, temperature, pressure, pleasure
• Somatosensory cortex:
  • Sensations are perceived here
  • homunculus: topological map of the surface of body, some more focus (like lips, hand, etc)
  • Violin players have larger representation areas in left hand fingers
• Two point discrimination:
  • Based on receptive field of sensory neurons at a point
  • Is indicative of Tactile Acuity

Pain

• Gate control theory:
  • non-painful input closes gates, so just massaging painful area isn’t painful.
  • Small nerve fibers open the gate, large close it
• Phantom limb: reorganisation of neural connections - neural plasticity
• remapping hypothesis, sensations felt in both face and phantom limb. Maybe sensory homunculus is adjacent
• Mirror therapy, VR treatment for phantom limb
• Somatosensory illusions

Hearing

• Outer ear catch, middle ear amplify, inner ear send messages
• Middle ear has Malleus, Incus, Stapes
• Inner ear has Vestibular system (balance) and Cochlea (hearing)
• Cochlea has tonotopic map. Frequency coding.
• Auditory cortex and dual pathways
• Broca’s area: speech production
• Wernicke’s area: speech comprehension

• Sensation	Perception
  Amplitude	Loudness
  Frequency	Pitch
  ?	Timbre

• Auditory hallucinations related to Broca’s area: more about speech synthesis in brain than comprehension
• Tinnitus: damage from acoustical trauma, infections, age, etc

Olfaction

• Chemoreceptors
• Olfactory bulb directly in forebrain
• Animals superior to humans

Gustation

• gustatory cortex not same as tongue area of somatosensory cortex but close
• Taste: sweet, sour, salty, bitter, umami
• Papillae: circumvallate, foilate, fungiform
• Supertasters: larger number of tightly arranged papillae. More sensitive to bitter.
• CD36 –> fat: sixth taste compound?
• 80% of taste is aroma through orthonasal (nose) and retronasal (mouth)
• Computational Gastronomy
• Gastrophysics
• White mug preferred for dark coffee
• Stronger preferred by brighter bg light

Multisensory integration

• Superior Colliculus is an Integration center
• Olfactory tubercule: auditory + olfactory
• Examples of crossmodal:
  • Sonic chip
  • digital seasoning
  • plate shape/colour affecting taste and quality judgements
• Orbitofrontal cortex: inputs from primary olfactory, gustatory, secondary somatosensory, superior (auditory) and inferior (visual) temporal gyrus, and emotion centers (amygdala)
• Synesthesia:
  • grapheme-colour
  • chromosthesia
  • number-form
  • personification
  • lexical-gustatory
• Learned associations:
  • cinnamon as sweet vs spicy
  • Masculine perfume as manager
  • lower pitch as a leader