Localisation / Lateralisation

• FUNCTIONAL AREAS OF THE BRAIN:

  1. Motor area: specific action (picking something up)
  2. Sensory area: skin sensations (temperature, pain, pressure)
  3. Frontal lobe: movement, problem solving, concentration, thinking behaviour, personality, mood.
  4. Broca's area: speech control
  5. Temporal lobe: hearing, language, memory
  6. Brain stem: consciousness, breathing, heart rate
  7. Parietal lobe: sensations, language, perception, body awareness, attention
  8. Occipital lobe: vision, perception
  9. Wernicke's area: language, comprehension
  10. Cerebellum: posture, balance, coordination of movement
• Outer layer of the brain: cerebral cortex is a 3mm layer covering the inner parts of the brain. Separates us from other animals as cortex developed with grey matter.
• Visual centres: located in visual cortex in the occipital lobe. Visual processing begins in retina (light enters and strikes the photoreceptors i.e. rods and cones). Nerve impulses from retina travel to areas of the brain via optic nerve. Most terminate in thalamus, this acts as a relay station passing info to visual cortex.
• Auditory centres: concerned with hearing. They are found in the temporal lobes on both sides of the brain where auditory cortex is. Begins in cochlea in inner ear, sound waves are converted to nerve impulses, and travel via auditory nerve to auditory cortex. Pit stop at brainstem where basic decoding happens - then onto thalamus which acts as a relay station and carries out further processing. Last stop is auditory cortex.
• Motor cortex: responsible for generation of voluntary motor movements. Located in frontal lobe along the bumpy region (the precentral gyrus) on both hemispheres. Different parts of motor cortex responsible for different parts of the body. These are arranged logically: region that controls foot is next to region for leg.
• Somatosensory cortex: detects sensory events from different regions of the body. In parietal lobe along a region called the postcentral gyrus. Uses sensory info from skin to produce sensations such as touch, pressure, pain etc.
• Language centres - Broca's area: named after Paul Broca, a French neurosurgeon who treated a patient called Tan, who understood language but couldn't say any words other than what became his name. Broca (1865) studied 8 other patients to conclude that an area in the frontal lobe (left hemisphere) was critical for language production.
• A criticism of Broca's area is that it other neuroscientists have found that when people perform cognitive tasks (nothing to do with their language), their Broca area is still active. Fedorenko (2012) expanded on this, finding that there were 2 regions of Broca's area - one for language, one for responding to cognitive tasks.
• Language centres - Wernicke's area: German neurologist discovered another area of the brain that was involved in understanding language, that was located in the back portion of left temporal lobe. Those with lesions on the area could speak, but couldn't understand language.
• There is a neural loop (arcuate fasiculus) running between Broca and Wernicke's areas.
• Hypothalamus stimulates and controls the release of hormones from the pituitary gland
• Sperry's experiment - a quasi experiment with 11 participants. Participants had split brain procedure. Participant gazes at a fixation point on a translucent screen. Slides are shown on each side, one picture per 1/10 of a second. Info presented in one visual field is only remembered again if presented by the same visual field.
• Quasi experiment: where the independent variable is naturally occurring
• Sperry lacks ecological validity - lab setting, knew they were being studied.
• Sperry's study is reductionist - most tasks involve collaboration between left and right. When we hear speech, we decode meaning from the words and the emotional tone of the voice.
• Sperry's experiment has ethical issues - the participants might have thought they were 'normal' and were therefore distressed by the results.
• Sperry used a non-representative sample
• Sperry's use of the quasi experimental design means that external reliability is hard to control. Study is also not repeatable
• Sperry's study is not generalisable.
• Sperry's qualitative data is detailed and increases validity of findings