Brain Imaging Techniques CT Scan: Computerized Topograph Scan MRI: Magnetic Resonance Imaging fMRI: Functional Magnetic Resonance Imaging PET Scan: Positron Emission Tomograph Scan EEG: Electroencephalogram or electrical recordings.

CT Scans: An x-ray of the brain. A CT scan is essentially a computerized assembly of several x-ray images taken from a series of different angles. With a CT, the resolution is much better than conventional x-rays, and the detail that can be seen is much greater. 

Tumor in Wernicke’s Area         MRI is a noninvasive imaging technique that does not use x-rays.   The process involves passing a strong magnetic field through the head.  The magnetic field used is 30,000 + times that of the earth's magnetic field.  It's effect on the body, however, is harmless and temporary.  The MRI scanner can detect radiation from certain molecules, which are present in different concentrations in different tissues. 

P E T S C A N PET measures the emission of positrons from the brain after a small amount of radioactive isotopes, or tracers,  have been injected into the blood stream.  A common example is a glucose-relative with embedded fluor-18.   With this molecule, the activity of different regions of the brain can be measured.  The result is a three-dimentional map with the brain activity represented by colors. 

After Implant of Dopamine-secreting Tissue Normal Brain ADHD Brain After Implant of Dopamine-secreting Tissue Brain Development in First Year of Life

EEG of Mouse with Epileptic Seizure EEG Cap Alert Deep Sleep

The Evolution of the Brain

Different areas of the brain have different roles.

Major Brain Regions: Brainstem Medulla Breathing, muscle tone and regulating circulation T h a l m u s C o r p c H y t P n M e d S i b Pons Connects brainstem with cerebellum & involved in sleep and arousal C e r r Cerebellum Coordination of voluntary movement and sense of equilibrium

Major Brain Regions: Midbrain Part of the brainstem twixt the hindbrain and the forebrain T h a l m u s C o r p c H y t P n M e d S i b Concerned with certain sensory processes and dopamine production Midbrain Reticular Formation Modulates muscle reflexes, breathing & pain perception. Also regulates sleep, wakefulness & arousal

Major Brain Regions: Forebrain Thalamus Relay station for all sensory info (except smell) to the cortex T h a l m u s C o r p c H y t e b x P n M d S i Cerebrum/Cerebral Cortex Hypothalamus Regulates basic needs fighting, fleeing feeding, and mating e Limbic System Involved in regulation of emotion, memory & motivation

THALAMUS It relays to the cerebral cortex information received from diverse brain regions. Sort of a requisite 'last pit stop' for information going to cortex. Axons from every sensory system (except olfaction) synapse here as the last relay site before the information reaches the cerebral cortex

Emotion and Memory are closely connected. Amygdala A little almond shaped structure, connects with the hippocampus. Hippocampus Is particularly involved with memory phenomena, specially with the formation of long-term memory (the one that, sometimes, lasts forever).

The pituitary gland may be king, but the power behind the throne is clearly the hypothalamus.

Major Brain Regions: Cerebral Cortex Convoluted outer layer of cerebrum Responsible for learning, memory, thinking, sensation and consciousness

Structure of the Cortex 1/8th inch thick 30 billion nerve cells + 270 billion Glial cells Each nerve cell makes 10,000 contacts each Approximately 300 trillion connections

Lobes of Cerebral Hemispheres primary motor cortex primary somatosensory cortex primary auditory cortex primary visual cortex Temporal (“tones”) - Devoted to auditory processing Occipital (“objects”) - Devoted to visual processing Parietal (“pressure”) - Devoted to sense of touch Frontal (“??”) - Devoted to control of muscle movement and other behavioral functions (e.g., personality)

Lobes of the Cerebral Cortex

Motor Area Sensory Area

Cerebral Laterality Idea of Hemispheric Specialization Broca’s Area Important in the production of speech Wernicke’s Area Important in the comprehension of language Idea of Hemispheric Specialization (“Left/Language & Right/Visual-Spatial”) leads to Split Brain Research by Sperry & Gazzaniga

Speaking the Heard Word LANGUAGE CENTERS Disrupts Understanding Disrupts Speaking Speaking the Heard Word Speaking the Written Word Angular Gyrus Speak & Understand, Unable to Read

(Right side of the brain controls the Left side of the body) Cerebral Hemispheres Corpus Callosum 200 million nerve fibers that connect Left & Right hemispheres. Allows communication between two sides of the brain. Each hemisphere’s primary connections are to the opposite side of the body (Right side of the brain controls the Left side of the body)

HE ART Split Brain What effect does cutting the Corpus Callosum Left Visual Field Right Visual Field Split Brain What effect does cutting the Corpus Callosum have on behavior? HE ART l “Say what you saw vs Point at what you saw” Retina Optic Chiasm Thalamus Left Visual Cortex Right Visual Cortex Corpus Callosum

CEREBELLUM Alcoholism causes brain shrinkage to the cerebellum

Central Nervous System Consists of the Brain and the Spinal Cord CNS is nourished and protected by the Cerebrospinal Fluid Blood-Brain Barrier Semi-permeable membrane-like mechanism that prevents some chemicals from passing between the bloodstream and the brain

Puh-leeez Don’t You Believe It “Everybody knows that we only use 10% of our brains.” “Imagine what we’d be like if we could use the other 90%!” Puh-leeez