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).
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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.