Emotion and Motivation Parts of brain important in control of emotional stress are: Hypothalamus – in diencephalon Limbic system – composed of nuclei and fiber tracts: - Cingulate gyrus - Septal nuclei - Amygdala - Hippocampus

Emotion and Motivation Hypothalamus and limbic system are involved in control of: Aggression = stimulation of certain areas of amygdala/hypothalamus causes aggression. Fear = electrical stimulation of other parts of hypothalamus and amygdala causes fear. Removal of limbic system = absence of fear (e.g monkey & snake) Feeding = feeding center and satiety center in hypothalamus; stimulation of feeding center = overeating stimulation of satiety center = stop eating Sex = sexual behavior and drive are regulated by hypothalamus and limbic system, but the cerebrum is also important in this control . Goal-directed behavior = stimulation area between frontal cortex and hypothalamus gives feeling of relief from tension, stimulating a site close to that causes feeling of being punished.

Frontal Cortex Damage An accident caused penetration of a thick long iron into Phineas Gage’s skull. he survived, but his personality changed, he became less responsible and lost his social inhibitions, used gross profanity.

Memory Medial temporal lope Memory = storage of learned information. Working memory – a limited capacity short-term memory that lasts only seconds to minutes. It is operated in frontal lobes of cerebral cortex. Dopamine is one of the most important neurotransmitters in the operation of Working memory. Long-term memory – storage of information which can last for hours, days or Years. The process of transferring memory from short-term to long-term is called consolidation of memory. GABA decreases memory consolidation, whereas glutamate, ACh and NE stimulate it. Medial temporal lope - Two types of long term memory: 1- Procedural memory = remember how to do something e.g ride a bike or swim 2- Declarative memory = remembering facts, e.g names.

Diencephalon (Thalamus, Hypothalamus & Pituitary Gland)

Diencephalon 1- Thalamus: - Gray matter forming most of the wall of 3rd ventricle. - Relay center for passage of sensory information to cerebrum. - Contains choroid plexus = source of CSF secretion. 2- Hypothalamus: - Located below the thalamus. - Forms floor of the 3rd ventricle. - Contains neural centers for: hunger, thirst and regulates: - body temperature - hormone secretion from pituitary glands - sleep and wakefulness - anger and fear - pain and pleasure

Diencephalon 3- Pituitary Gland: - Located inferior to the hypothalamus. - Connected to the hypothalamus by a tract of neurons (Stalk). - The tract is called hypothalamo-hypophyseal tract. - Hormones secreted by hypothalamus (ADH + Oxytocin) - ADH and oxytocin travel down the tract to pituitary and stored prior secretion. - Oxytocin = contraction of uterus during delivery (child-birth). - ADH = reabsorption of water by kidney. - Hypothalamic neurons also secret: releasing hormones and inhibiting hormones.

Mesencephalon (Midbrain) Located between diencephalon and pons. Composed of: 1- Corpora quadrigemina : four rounded bodies in the dorsal part of midbrain involved in visual and auditory functions: - superior colliculi = visual reflexes - inferior colliculi = auditory information 2- Cerebral peduncles = composed of ascending and descending fiber tracts. 3- Red nucleus = gray matter area in midbrain which maintains connections between cerebrum and cerebellum (motor co-ordination). 4- Substantia nigra = connections with basal neuclei (motor co-ordination).

Rhombencephalon (Hindbrain) Composed of 2 regions : 1- Metencephalon (pons and cerebellum): a) Pons ; located between midbrain and medulla. contains several nuclei contains respiratory control centers: apneustic and pneumotaxic. b) Cerebellum: 2nd largest structure of the brain. - outer gray and inner white matter. - Connected with pons, medulla, and spinal cord through fibers. - co-ordinates body movements. 2- Myelencephalon (medulla oblongata): - located between pons and spinal cord (3 cm) - all fiber tracts that provide communication between spinal cord and brain must pass through medulla. - contains important nuclei - contains vital centers = breathing and cardiovascular.

Respiratory Control Centers

Spinal Cord Extends from level of foramen of magnum to 1st lumbar vertebra. - Arrangment of gray and white matters is opposite to the brain. Gray matter is surrounded by white matter. The gray matter is arranged in the form of H. The white matter is composed of ascending (sensory) and descending (motor) tracts. Examples of such tracts: Spinothalamic tract = carriers sensory touch to thalamus. Corticospinal tract = carries motor fibers from cortex down spinal cord.

Spinal Cord Tracts 1- Ascending tracts: convey sensory information from: - cutaneous receptors (skin), - proprioceptors (muscle and joint senses) - visceral receptors (internal body organs) *senses from right side of the body are connected to the left brain and senses from left side of the body are connected to right brain.

Spinal Cord Tracts 2- Descending tracts: convey motor signals from brain to the periphery. There are two major groups: 1- Corticospial (pyramidal) tracts 2- Extrapyramidal tracts

Spinal Nerves 8 Cervical 12 Thoracic 5 Lumbar 1 Coccygeal 5 Sacral 31 pairs of spinal nerves : 8 Cervical 12 Thoracic 5 Lumbar 1 Coccygeal 5 Sacral

Spinal Reflex - Reflex = an unconscious motor response to a sensory stimulus.