Module 3 The Brain

* Electroencephalograph (EEG): * records “waves” of electrical activity in the brain using metal electrodes * Computerized axial tomograph (CAT): * thousands of X-ray photos of the brain are combined to form a cross- sectional picture * Magnetic resonance imaging (MRI): * produces three-dimensional images of the brain’s soft tissues by detecting magnetic activity from nuclear particles in brain molecules

* Positron emission tomography (PET): measures neural activity in different brain regions over several minutes by monitoring sugar glucose consumption * Functional magnetic resonance imaging (fMRI): measures neural activity in different brain regions averaged over seconds by monitoring blood oxygen levels

* Their names come from their physical location in the human embryo. * Hindbrain: Located above the spinal cord, * Midbrain: Located above the hindbrain * Forebrain: Located above the midbrain

* Hindbrain consists of: * Medulla: controls breathing, heart rate, swallowing, digestion, and posture * Pons: associated with sleep and arousal * Cerebellum: regulates and coordinates body movement and may play a role in learning

Reticular formation: * regulates and maintains consciousness * plays an important role in controlling arousal

Controls complex emotional reactions, cognitive processes, and movement patterns. Consists of: * Thalamus: the brain’s sensory relay station * Limbic system: influences fear, aggression, and new memories * Cerebral cortex: located on top of these structures; the most complex part of the brain

* Brain’s Sensory Switchboard * Directs incoming information from the sensory systems (except smell) to the appropriate location on the cortex.

* a doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres * associated with emotions such as fear and aggression and drives such as those for food and sex * includes the hypothalamus, hippocampus and amygdala

* neural structure lying below (hypo) the thalamus * directs several maintenance activities * eating * drinking * body temperature * helps govern the endocrine system via the pituitary gland * linked to emotion

* Structure linked to the processing/formation of new explicit memories * Manufactures new neurons

* two almond-shaped neural clusters that are components of the limbic system and are linked to emotion, especially rage and fear

* Electrode implanted in reward center

* The cerebral cortex is divided into two rounded halves, called the cerebral hemispheres. * These hemispheres are connected together at the bottom by the corpus callosum. * Both hemispheres are divided into four major sections called lobes:

* Occipital Lobes * include the visual areas, each of which receives visual information from the opposite visual field * Temporal Lobes * include the auditory areas, each of which receives auditory information primarily from the opposite ear

* Functional MRI scan of the visual cortex activated by light shown in the subject’s eyes

* Frontal Lobes * involved in speaking and muscle movements and in making plans and judgments * Parietal Lobes * include the sensory cortex

* Motor Cortex * area at the rear of the frontal lobes that controls voluntary movements * Sensory Cortex * area at the front of the parietal lobes that registers and processes body sensations

* Areas of the cerebral cortex that are not involved in primary motor or sensory functions * Involved in higher mental functions such as learning, remembering, thinking, and speaking

* Aphasia * impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding) * Broca’s Area * an area of the frontal lobe that directs the muscle movements involved in speech * Wernicke’s Area * an area of the left temporal lobe involved in language comprehension and expression

* Right hemisphere: superior to the left hemisphere in visual and spatial tasks, recognizing nonlinguistic sounds, identifying faces, and perceiving and expressing emotions * Left hemisphere: superior to the right hemisphere at language, logic, and providing explanations for events * Women may be more likely than men to use both hemispheres for language (their brains are more bilateralized).

* 65% have speech on the left (95 % RH) * Weak correlations: * + gifted & creative * - reading disabilities, epilepsy, alcoholism, schizophrenia, allergies, MR

Corpus Callosum –large bundle of neural fibers connecting the two brain hemispheres and carrying messages between the hemispheres

Corpus Callosum

–Split Brain –a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them

* The information highway from the eyes to the brain

* Plasticity: the flexibility of the brain to alter its neural connections following injury * Hemispherectomy: a radical surgical procedure in which one of the cerebral hemispheres is removed to control life-threatening epileptic seizures. The remaining healthy hemisphere takes over many of the functions of the removed hemisphere. * Plasticity is highest in childhood, but it also occurs in older adults.

--the brain’s capacity for modification as evident in brain reorganization following damage (functional plasticity) --and in experiments on the effects of experience on brain development

* 1. Avoid Harmful Substances * 2. Exercise * 3. Eat Sensibly * 4. Challenge Yourself Mentally * 5. Wear Your Helmet/Seat Belt.

* Beneficial substances allowed to enter the brain through the blood-brain barrier are blood gases, such as oxygen, and small nutritional molecules. * An important nutritional molecule transported out of the bloodstream in this way is glucose. * Scientists have learned how to trick the blood- brain barrier into accepting therapeutic drugs through the bloodstream to the brain.