PSYC100 0922 The Brain Most important organ Physiologically speaking Weighs approx 1400g 3lbs Important brain functions Perception of incoming stimuli Integration and association of stimuli with information in memory Neural activity resulting in coordinated motor responses to stimuli Major Parts of the Brain Cerebrum Cerebellum Brain Stem Spinal cord Cranial Nerves Brain stem Spinal Cord Cranial nerves Input to the brain is from Output from the brain Gray Matter Contains cell bodies of neurons White Matter Consists of tracts containing myelinated axons Foramina are holes in the skull through which nerves pass Foramen magnum is the largest of these holes Spinal cord travels through this hole Means marrow inner substance The first swelling on the top of the spinal cord Above FM Brain stem Below FM Spinal Cord Medulla Regulates Heartbeat Breathing Muscle tone Swallowing In the medulla nerves coming from and going to the left and right sides of the body cross such that the right side of the brain controls the left side of your body while the left side controls the right side of your body a larger swelling above the Medulla Pons Bridge Controls Arousal Sleep Dreaming Reticular Formation Interconnected neurons running through the Pons and medulla and beyond About the size of your little finger Responsible for Keeping you alert and aroused Ability to selectively attend to certain kinds of stimuli Ability to ignore constant unchanging stimuli and becoming alert to changes in information If you electrically stimulate the RF of a sleeping rat The rat immediately awakens Destroy The RF The rat falls into a coma will never wake Implicated in comas in humans One part of the RF is the RAS Reticular activating system stimulates the upper part of your brain keeping you awake and alert Some brain imaging studies have suggested that the RAS is involved in ADHD Cerebellum At the base of the skull behind the Pons below the main part of the brain Controls all involuntary rapid fine motor movements Coordinated motor movements and balance Controls voluntary movements that must take place in rapid succession Helps you keep track of where your arms and legs are Because of your cerebellum you don t have to consciously think about your posture muscle tone and balance Learned reflexes skills and habits are stored there such that they re relatively automatic Under normal circumstances Hippocampus Located within the temporal lobes on both sides of the brain Important for forming long term memories Acetylcholine ACh Neurotransmitter used for muscle control is important for the memory functions of the hippocampus People with Alzheimer s for example have much lower levels of ACh than normal Amygdala Located near the hippocampus Responsible for fear memory of fear anger Sensory information goes to the amygdala before it gets to higher parts of the brain Thus people can react to danger very quickly Kluver Bucy syndrome 1939 Discovered that monkeys with large amounts of their temporal lobes removed including amygdala were completely unafraid of snakes and humans which are normally fear provoking stimuli Important sub cortical structures Limbic System Old brain Thalamus inner Chamber A relay station for incoming sensory information Olfaction is the only sense that cant be affected by damage to the thalamus Regulates body temperature hunger thirst sleeping waking sexual activity emotions Controls the Pituitary regulates hormones Hypothalamus 4 F s Feeding Fighting Fear Fooling around Hippocampus Located within the temporal lobes on both sides of brain Important for forming long term memories of episodic events Disassociation having a memory of an event but not remembering the emotional aspects or vice versa Cerebral Cortex Made up of tightly packed neurons Only about a tenth of an inch thick on average Full of wrinkles Grayish pink in appearance Tightly packed cell bodies are gray and the small blood vessels appear pink The wrinkling of the cortex allows a much greater area of cortical cells to fit in the confined space of the skull Flattened out the human cortex would be about 2 or 3 square feet Broken into frontal temporal parietal occipital lobes 1 per hemisphere In the back of the head process initial visual information Contains the somatosensory cortex which process information from the skin and the body s internal receptors for Lobes Occipital lobes Parietal Top and the back of the brain Touch Temperature Body position Temporal Just behind the temples Contain the primary auditory cortex In most people the left temporal lobe is very important for language Frontal Front of the brain Personality Planning Memory storage Complex decision making Areas devoted to language left hemisphere for most Frontal lobe connected to limbic system through hypothalamus Helps us control our emotions Phineas Gage suffered damage to his frontal lobe He lost emotional control because connections between his frontal lobe and structures in his limbic system especially the amygdala were damaged Perception The key mediator between stimulus and response The source of most knowledge that humans acquire Adaptive significance The primary function of perception including all of its components is survival The problem of visual perception Each retina contains over 125 million receptors rods cones each of which responds over tie in a complex way to the light falling upon it The task of the visual system is to create from this mass of raw data a helpful veridical representation of the outside world The study of perception involves at least three elements Physical qualities of the world physical Transformations of these physical qualities by the nervous system physiological The experience of these events by the observer psychological Begins with receptors which act as transducers Change one form of energy e g light energy into another i e neural impulses Sensation From physical to physiological Perception From physical to psychological Perception often entails the recognition of something Recognition is the interaction between perception and memory Why Study perception Power of perception Visual system can recognize millions of different stimuli Perception seems so easy Our perceptual abilities look deceptively simple Perception is transparent to the perceiver We only notice it when something goes wrong What would life be like if we could not recognize any patterns Visual blind spot Hemineglect Visual agnosia Inability to recognize an object
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