Brain One of the largest organs in the adult body—3 pounds (1400 g)  Almost 100 billion neurons and as many glia  Most new neurons are produced before and shortly after birth  Synapses are made and broken throughout life  Neurons do NOT undergo mitosis 1

Brain 4 major portions Cerebrum-- Largest part of brain in humans – Higher mental function, memory, personality Diencephalon- processes sensory info- mostly gray matter- controls emotional experiences (in limbic system) Cerebellum-Balance and coordination, coordinates voluntary muscle movements Brain Stem- Controls visceral functions (autonomic)

Brainstem Mostly white matter Visceral, autonomic functions “Reptilian” 3 parts: – Medulla oblongata – Pons – Midbrain

Brainstem: medulla oblongata - Lowest part of the brainstem - Continuation of spinal cord, above foramen magnum - Mostly white matter 4

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Brainstem: medulla oblongata Functions:  -Reflexes   heart rate, dilation of blood vessels, breathing rate  - Other reflexes: vomiting, coughing, sneezing, blinking, etc 6

Brainstem: Pons  Pons  -Located above the medulla and below the midbrain  -Contains reflexes to regulate respiration 7

Brainstem: Midbrain -Located above the pons and below the cerebrum; forms the midsection of the brain -some cranial nerve reflexes like pupil dilation & eye movement

Cerebellum Structure  Second largest part of the brain—contains most neurons  most computing power  Located below cerebrum; transverse fissure separates these two 9

Cerebellum: function Functions: shares with cerebrum – Helps control posture and balance – Coordinates motor commands from cerebrum with sensory info coming from muscles  makes muscle movement “smooth” and “coordinated”

Diencephalon “between brain” near 3 rd ventricle A. Thalamus main relay station for sensory impulses on way to cerebrum recognition of touch, temperature makes associations between sensory impulses and pleasantness or not

Diencephalon B. Hypothalamus- regulates & coordinates autonomic activities, helps control responses made by visceral effectors, link between “psyche” and soma (mind’s influence over body and how you feel), hunger, sleep

Diencephalon C. Pineal gland: Biological clock, releases melatonin into blood - Melatonin: “sleep hormone” - subtle changes in sunlight and lunar light cause shifts to melatonin cycle - jet lag? - night shift?

Diencephalon D. Optic chiasma: region where right and left optic nerves cross each other before entering the brain

Cerebrum Cerebrum: Largest part of brain in humans – 2 halves= cerebral hemispheres – Higher mental function – Somatic senses and “special” senses – Motor control – Consciousness, language Cerebral cortex- outermost layer; gray matter

Cerebral fissures Longitudinal fissure: divides cerebrum into L and R hemisphere

Cerebral fissures Central sulcus: groove between frontal and parietal lobes

Cerebral fissures Lateral fissure: deep groove between temporal lobe and frontal/parietal lobes

Cerebral fissures Parietooccipital sulcus: groove between occipital and parietal lobes

Lobes of Cerebrum Frontal Lobe: reasoning, thinking, attention, language (higher cognitive functions) – Broca’s area makes speech possible – Primary motor cortex coordinates and initiates motor movements

Lobes of Cerebrum Parietal Lobe: Integrates sensory info: touch, pain, temperature, relation of body parts – Visual processing – Spatial mapping – Number representation

Lobes of Cerebrum Temporal Lobe: hearing, perception, face recognition Wernicke’s area: at intersection of temporal, occipital, and parietal on LEFT SIDE of brain; Helps you recognize and understand language

Patient with stroke in Left posterior temporal lobe Boy, I'm sweating, I'm awful nervous, you know, once in a while I get caught up, I can't get caught up, I can't mention the tarripoi, a month ago, quite a little, I've done a lot well, I impose a lot, while, on the other hand, you know what I mean, I have to run around, look it over, trebbin and all that sort of stuff. Oh sure, go ahead, any old think you want. If I could I would. Oh, I'm taking the word the wrong way to say, all of the barbers here whenever they stop you it's going around and around, if you know what I mean, that is tying and tying for repucer, repuceration, well, we were trying the best that we could while another time it was with the beds over there the same thing…

“I certainly have seen individuals with Wernicke's aphasia carry on very well in their lives, for example taking buses to their appointments, caring for their children, and even driving. Thus, they clearly 'think'. How much of this is verbally-mediated thought though is unclear.”

Lobes of Cerebrum Occipital Lobe: vision: color, orientation, motion – Must project to other lobes – Vision projects to temporal lobe to recognize identity of object