Brain Lobes and Functions

Temporal Lobe

  • Located in the gold area, resembling the thumb of a boxing glove.
  • Important for auditory processing, object recognition & naming.
  • Damage can lead to agnosia: recognizing an object but being unable to name it, which means losing connection between recognition and naming of an object.
  • Specific regions are assigned to identifying faces.
  • Damage to facial recognition regions can lead to prosopagnosia: inability to identify faces.
  • Experiment on monkeys showed:
    • Neurons in the temporal lobe fire when exposed to monkey faces.
    • Response decreases when facial features are jumbled or partially obscured.
    • Response varies with different monkey faces and decreases further when shown human faces

Frontal Lobe

  • Curved fingers of the boxing glove, separated from the parietal lobe by the central sulcus.
  • The strip on the frontal lobe side of the central sulcus is the primary motor cortex.
  • Stimulating specific areas of primary motor cortex causes specific muscle contractions.
  • The body is mapped onto the primary motor cortex.
  • Contralateral control: stimulating the left side affects the right side of the body and vice versa.
  • Involved in personality, planning, social awareness, and higher human functions.
  • Phineas Gage Case Study
    • Phineas Gage was a railroad worker in the 1800s.
    • An explosion caused a tamping rod to go through his head, damaging his prefrontal cortex. The rod was about three meters long.
    • Gage survived but experienced significant personality changes (foul-mouthed, impatient, irresponsible).
    • The accident led to the mapping of personality traits to the prefrontal cortex.
    • Lost his awareness of the consequences of his behavior.

Parietal Lobe

  • The strip of cortex immediately behind the central sulcus.
  • Contains the primary somatosensory cortex.
  • Stimulation of specific areas leads to localized sensation on specific areas of the body (contralaterally).
  • Body is mapped onto the somatosensory cortex.
  • Disproportionate representation: sensitive areas like lips and fingertips have larger representation.
  • Allows us to locate where we've been touched due to sensory inputs from the body relayed through the thalamus to the somatosensory cortex.
  • The motor and somatosensory maps are also known as homunculi
  • Functions: Filters out important stimuli to allow appropriate responses.
  • Damage to the right parietal lobe can lead to contralateral neglect: inability to process sensory information from the left side of the body.
    • Example: An individual with contralateral neglect might dress the right side of their body but neglect the left side.
  • If the person's attention is brought to the neglected side, they become aware of it.
  • Damage to the left side of the parietal lobe does not result in neglect of the right side of space.
  • Reasoning and data analysis are mapped to the left side, while spatial and artistic tasks are mapped to the right side.
  • The corpus callosum connects and integrates both sides of the brain; mapping functions separately is not always accurate.

Occipital Lobe

  • Receives and processes visual information.
  • Uses integrated approach with specific and extended areas for binocular vision, depth perception, and visual acuity.
  • Association areas help in understanding, perceiving, and articulating what we see.
  • Occipital lobe damage example: A patient lost the ability to perceive motion.
    • Could see objects but not detect movement.
    • Saw waterfalls as static images.
    • Perceived cars as appearing in different locations without fluid motion.

Brain Damage Patients

  • Much of what we know about the lobes comes from brain-damaged patients.
  • Limitations: no two patients are alike, limiting conclusions.

Brain Scanning

  • PET (Positron Emission Tomography) scanning and MRI (Magnetic Resonance Imaging) & fMRI are driving our understanding further forward, allowing visualization of brain activity during specific tasks.
  • PET involves injecting a radioactive substance to label high-energy-consuming areas of the brain.
  • Different areas of the brain are activated when listening to, seeing, generating, or speaking words.

Language Processing

  • Auditory cortex lights up when hearing words.
  • Visual cortex lights up when seeing words.
  • Wernicke's area: Interprets the meaning of words.
  • Broca's area: Produces words.
  • Motor cortex controls the lips, mouth, and tongue for articulation.
  • When speaking a written word:
    • Visual cortex relays information to Wernicke's area for interpretation.
    • Broca's area activates to prepare for language production.
    • Motor cortex generates mouth and tongue movements to speak.
  • When speaking a heard word:
    • Auditory cortex activates.
    • Wernicke's area interprets the words.
    • Broca's area prepares to produce the language.
    • Motor cortex articulates the words.
  • Damage to language processing centers leads to aphasias.
    • Damage to Wernicke's area results in inability to understand visual or spoken communication (Wernicke's aphasia).
    • Damage to Broca's area results in the ability to understand communication, but inability to produce sensible spoken or written language (Broca's aphasia).
    • The user is prompted to watch a YouTube clip to learn more about the topic.

Integration and Complexity

  • Seeing something involves more than just the visual cortex.
  • Visual system detects size, color, shape, and motion.
  • Other senses, experiences, and memories enrich the experience.
  • Example: Seeing a car involves visual input plus hearing, smelling, and touching the car.
  • Learning, memory, emotions, and motor responses come into play.