Neuroimaging techniques: MRI, fMRI, and PET scans

The Brain: Neuroplasticity and Tools of Discovery

• Psychology is concerned with human biology to understand the biological basis of behavior and mental processes.
• Neuroplasticity is enabled by the interaction of biology and experience, allowing the brain to adapt and rewire itself.
• Techniques for studying the brain's connections to behavior and mind include case studies, lesioning, and advanced technologies like brain scans.
• Hippocrates correctly located the mind in the brain, but Aristotle believed the mind resided in the heart.
• Science has proven that the brain, not the heart, is responsible for emotions like love.
• Franz Gall proposed phrenology in the early 1800s, suggesting that bumps on the skull reveal mental abilities and character traits.
• Mark Twain used a false name to test a phrenologist, exposing the field's lack of scientific validity.
• Phrenology focused attention on the idea of the localization of function, where different brain regions have specific functions.
• Psychological scientists use empirical and evidence-based methods, relying on observation and experimentation to study the brain.
• Biological psychologists use advanced technologies to study the links between biological and psychological processes.
• Neurons communicate through electrical signals and chemical messages across synapses.
• Experiences can "wire" the brain, leading to adaptation and changes in neural pathways.
• Specific brain systems serve specific functions, though not in the way Gall originally supposed.
• The brain integrates information from different systems to construct experiences.
• Biological psychology studies the links between biological and psychological processes, with some practitioners calling themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists.
• We are biopsychosocial systems, composed of subsystems themselves made of smaller subsystems, from cells to organs to systems to the individual within a family, community, and culture.
• The biopsychosocial approach integrates biological, psychological, and social-cultural levels of analysis
• Culture, defined as shared beliefs, ideas, attitudes, values, and traditions of a group, is crucial in understanding human behavior within a biopsychosocial approach.

Neuroplasticity

• The brain is sculpted by genes and life experiences
• Neuroplasticity, the brain's ability to change, reorganizing after damage or creating new pathways, persists throughout life but is strongest in childhood. London taxi driver trainees who spend years learning the city's streets showed an enlarged hippocampus, the memory center for spatial memories, after passing the final test.
• Bus drivers who navigate fixed routes do not experience the same change.
• Daniel Kish, who is blind, uses echolocation to navigate and engages the brain's visual centers.
• Well-practiced pianists have a larger-than-usual auditory cortex area, highlighting the impact of practice on brain structure
• Practice sculpts the brains of ballerinas, jugglers, and unicyclists.
• An hour of learning produces subtle brain changes.
• Neuroplasticity allows humans to adapt to a changing world

Tools of Discovery: Having our Head Examined

• Understanding the brain is among the largest scientific challenges.
• The mind is what the brain does, with billions of neurotransmitter molecules released across trillions of synapses.
• Early case studies helped localize some brain functions by observing the effects of brain damage
• Damage to one side of the brain often causes numbness or paralysis on the opposite side.
• Damage to the back of the brain disrupts vision.
• Scientists can selectively lesion (destroy) tiny clusters of normal or defective brain cells to observe the effect on brain functions.
• Damage to one area of a rat's hypothalamus can reduce eating, while damage to another area can cause overeating.
• Neuroscientists stimulate various brain parts electrically, chemically, or magnetically to observe the effect.
• Electrical stimulation may cause people to giggle, hear voices, turn their head, feel themselves falling, or have an out-of-body experience
• Scientists use modern electrodes and optogenetics to study individual neurons
• Optogenetics involves programming neurons to respond to light, allowing researchers to control neuron activity Electroencephalogram (EEG) records electrical waves sweeping across the brain's surface
• Magnetoencephalography (MEG) measures magnetic fields from the brain's natural electrical activity in special rooms that isolate magnetic signals.
• Computed tomography (CT) scans examine the brain by taking X-ray photographs to reveal brain damage.
• Positron emission tomography (PET) scans depict brain activity by showing each brain area's consumption of glucose.
• Active neurons consume glucose, with the brain using 20% of calorie intake while only being 2% of body weight. Magnetic resonance imaging (MRI) brain scans use a strong magnetic field and radio waves to create detailed pictures of soft tissues, revealing brain anatomy.
• Functional MRI (fMRI) reveals the brain's functioning by comparing successive MRI scans
• fMRI scans detect blood flow and show specific brain areas activating during different tasks.
• Functional near-infrared spectroscopy (fNIRS) shines infrared light on blood molecules to identify brain activity.
• The Human Connectome Project uses cutting-edge diffusion tensor imaging MRI methods to map the brain's interconnected network of neurons

Brain Regions and Structures

• Vertebrate brains contain three main divisions: the hindbrain, midbrain, and forebrain.
• The brainstem's base of the hindbrain is the medulla, controlling heartbeat and breathing.
• The pons helps coordinate movements and control sleep.
• Contralateral hemispheric organization cross-wiring is where most nerves to and from each side of the brain connect with the body's opposite side
• Sitting atop the brainstem is the forebrain's thalamus, which acts as the brain sensory control center
• Inside the brainstem, between the ears, lies the reticular formation, which filters information and plays a role in controlling arousal.
• Extending from the rear of the brainstem is the cerebellum which coordinates voluntary movement and balance, and enables nonverbal learning and memory.
• The limbic system, associated with emotions, drives, and memory formation, neural system located mostly in the forebrain
• The hypothalamus directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system, and is linked to emotion and reward.
• The hippocampus processes explicit, conscious memories. The amygdala is linked to emotion.

Cerebral Cortex and Lobes

• The cerebrum contributes 85% of a brain's weight.
• The cerebral cortex is a thin layer of interconnected neural cells covering the cerebral hemispheres, enabling perceiving, thinking, and speaking.
• Humans are distinct due to their size and interconnectivity of the cerebral cortex
• Each hemisphere's cortex is subdivided into four lobes, separated by prominent fissures, or folds. Starting at the front of your brain and moving over the top, there are the frontal lobes (behind your forehead), the parietal lobes (at the top and to the rear), and the occipital lobes (at the back of your head). Reversing direction and moving forward, just above your ears, you find the temporal lobes.
• The motor cortex is at the rear of the frontal lobes that controls voluntary movements
• Foerster and Penfield mapped the cortex using the fact the brain has no sensory receptors. They stimulated different Cortical areas and observed the body's responses
• Body parts requiring precise control, such as the fingers and mouth, occupy the greatest amount of cortical space
• The Somatosensory cortex is at the front of the Parietal lobes that registers and processes body touch and movement Sensations
• Parts of the lobes, which were large and unusually shaped in Einstein's normal-weight brain, enable mathematical and spatial reasoning
• The Prefrontal cortex located in forward part of frontal lobes enable judgement
• Phineas Gage had damage to his frontal lobe that altered his personality
• Vision : Any visual information received now is going to visual cortex in your occipital lobe
• Auditory: Any Sound processed by your auditory cortex in your temporary lobes

Brain : Damage Response and Brain Hemispheres

• Severed neurons in the brain (and spinal chord) do not regenerate
• With Neural reorganisation , the young brain's plasticity, undamaged hemisphere can develop extra connections
• Similar reassignment of other function may occur when damage occurs
• Neurogenesis (producing new neurons) is one self-repair researchers are debating
• Lateralization: Brain hemispheres serve differing functions; Research spanning more than a century has shown that lefthemisphere accidents, strokes, and tumors can impair reading, writing, speaking, arithmetic reasoning, and understanding. Similar righthemisphere damage has less visibly dramatic effects.
• Hemispheres communicate via the corpus callosum
• Seizures are caused by abnormal brain activity

Split Brain

• Gazzaniga asked split-brain to stare at a dot as he flashed HE*ART
  • HE appeared in their left visual field (which transmits to the right hemisphere) and ART in the right field (which transmits to the left hemisphere).
• The patient reported to seeing ART But when asked to point with their left hand to what they had now seen they pointed to HER
• Left hemisphere is verbal, and the right hemesphere excels at visual perception
• The brain in heathy people confirm each hemi makes contributions to integrated functioning of the whole brain

Sleep: Consciousness

• Psychologists define consciousness as our subjective self awarness and environment
• Cognitive neuroscience is the interdisciplinary study of brain activity linked with our brain mental processes. The question of how consciousness arises form material brain is a hard problem.

Check Your Understanding

• The two-track mind
  • We are awear with little more than what's of the screen of consciouseness
  • much of our brain happens off stage out of sight -Thinking, knowing, remembering and communication all run on two independent ways
  • Conscious delibrate "high road" and an automatic unconscious "Low road" Which creates dual processing
• Parallel processing: Our mind care of rountine bussiens
• Sequential processing: Mind best for sloving problems

Sleep: Sleep Stages and Theories

• Sleep is a state of consciousness
• Periodic (natural loss)
• Sleep is distinct form unconsciousness resulting from a coma.
• Our circadian Rhythm (biological clock) : Regular bodily rhythms, that occur in a 24 hours

Sleep Cycle / Stages

• Stage 3: Last 30 Mins your brain emits Large slow delta waves and you are hard to awaken
• REM (Recurring eye moment sleep)
  • Rapid eye movement: Brain activity rises
• Our brain heart gets faster our breathing becomes irregular and our eyes dart behind our chords lies.

REM Bound: It may not move but internally they are aroused.