1.6DEFG Chemical and Bodily Senses

Overview of Biological Bases of Behavior

  • Focuses on the chemical and bodily senses that influence perception and behavior.

Chemical Senses

  • Chemical Senses: Two major chemical senses are smell (olfactory) and taste (gustation).
Smell (Olfaction)

  • Olfactory System:

    • Odorant molecules absorbed into nasal mucus.
    • Stimulate olfactory receptors in the nasal cavity.
    • Converts stimuli to neural messages through transduction.
    • Processed in the brain.

  • Limbic System's Role:

    • Smell bypasses the thalamus, going directly to the limbic system.
    • Links scent with emotions and memories, explaining the emotional connection to smells.

  • Pheromones:

    • Chemical signals that influence behavior within species, notably in non-human animals.
    • Controversy exists over human pheromones; however, they may play a role in attraction.
    • Notable decline in sense of smell with age.
Taste (Gustation)

  • Gustation Process:

    • Involves taste buds (located on the tongue, throat, and soft palate) and olfactory cues (smell).
    • Four primary tastes: sweet, salty, sour, bitter.
    • Additional tastes: umami (savory), oleogustus (taste of fat).
    • Loss of taste buds begins around age 50-60.
    • Saliva aids in taste perception by transporting flavors to taste buds.

  • Supertasters:

    • Individuals with heightened sensitivity to tastes and a greater number of taste buds (25% of population; more common in women).

  • Medium Tasters and Nontasters:

    • Medium tasters have an average number of taste buds, while nontasters are less sensitive to bitter compounds (25% of population).
Sensory Interaction
  • Definition: Interaction between senses; one sense can influence another.
  • Example: Holding the nose while tasting can diminish flavor perception, while releasing can enhance it.

Touch

Touch Sensation
  • Touch Structure:
    • Touch receptors in the skin signal through sensory nerves to the spinal cord and then to the thalamus.
    • Information is relayed to the somatosensory cortex for touch perception.
    • Stimulation of both warm and cold receptors results in the perception of heat.
Pain

  • Pain as a Warning Sign: Indicates bodily distress; exists in various forms and intensities.

    • Combines bottom-up (sensory) input with top-down (psychological) processing.
    • Vital for survival; brain can modulate pain experience.

  • Gate-Control Theory:

    • Proposes a 'gate' in the spinal cord that controls pain perception.
    • Increased firing of neurons equals greater pain perception.
    • Treatments (e.g., massage, acupuncture) can activate pain-relieving fibers.

  • Endorphins and Pain Management:

    • Psychological factors (like distraction) and biological factors (endorphin release) can reduce pain perception.
    • Genetic predisposition affects pain sensitivity.

  • Phantom Limb Sensations:

    • After limb amputation, some individuals report sensations of pain or movement in the missing limb (phantom pain).

Balance & Body Movement

Kinesthetic Sense
  • Kinesthetic Sense:
    • Governs the awareness of body movement and position, crucial for coordination and control during activities.
Vestibular Sense
  • Vestibular Sense:
    • Maintains balance and spatial orientation, influenced by semicircular canals in the inner ear detecting head motion.

Perception Activities

  • Kinesthetic Activity:

    • Have participants close eyes and touch their nose; helps understand body awareness and coordination.

  • Vestibular Activity:

    • Simple spinning exercise to explore effects of dizziness on balance.

  • Depth Perception Activity:

    • Toss and catch exercise with one eye closed emphasizes challenges in depth perception.

  • Touch Perception Activity:

    • Test sensitivity of sharp vs. soft stimuli on different body parts to observe varying sensation levels; assesses touch perception effectively.