Brainstem Survival and maintenance functions Crossover point where most nerves to and from each side of the brain connect with body’s opposite side
Brainstem Medulla - heart rate, breathing, blood pressure and has pathway for motor movement Pons – Helps coordinate movement Reticular Formation – Sleep and arousal
Brainstem Thalamus –Sits at the top of the brainstem –Relays sensory info (except smell), spatial sense, and motor signals to sensory areas of cerebral cortex and transmits replies to cerebellum and medulla –Helps regulate consciousness, sleep, and alertness –One consequence of damage = fatal insomnia
Cerebellum – “Little Brain” –Nonverbal learning and memory, – Coordinates voluntary movement and balance –Controls Learned/skilled movements that are automatic (i.e., walking)
Cerebellum Damage Affects fine movement, gait, equilibrium, posture, and voluntary movement causing Errors in force, direction, speed and amplitude of movements.
Other Cerebellum Damage Dysarthria – speech articulation Dysmetria – judging distances and range of movements Dysdiadokinesia – inability to perform rapid alternating movements Other Ataxia
Hypothalamus –Hunger, thirst, body temp., reproductive behavior –Controls pituitary gland –Emotion and “Reward Center” (Olds & Milner (1954)) Hippocampus –Forms new memories (episodic) –Spatial orientation Amygdala –Aggression, fear, and perception of them –Processing/encoding emotional memories –Regulating feeding
Limbic System Damage Hypothalamus – Death Amygdala – Loss of fear, impaired emotion recognition in faces, impaired recognition of social emotions, impaired memory for emotional material Hippocampus – Amnesia (anterograde), failure to remember spatial layouts/landmarks –H.M. – shows damage in Alzheimer’s
Question? The limbic system is involved in controlling basic drives important for our survival as a species, feeding and reproducing. But it is also instrumental to the experience of fear and aggression. What do you make of the fact that these two particular emotions (unlike say, happiness or melancholy) are controlled by the same system that helps ensure our survival? What does Memory have to do with this?
Cerebral Cortex Fabric of interconnected neural cells that covers the cerebral hemispheres Cortex=bark Ultimate control and information processing structure Higher Functions/Newer neural networks 85% of brain weight Axons project down into brain, connecting it with other brain structures
Cerebral Cortex Two halves, four lobes, separated by Fissures –Frontal lobe Judgement, planning, Decision- making, inhibition, personality Motor cortex –Parietal lobe Sensory cortex (touch) Math, spatial reasoning –Temporal lobe Auditory cortex, visual memory language –Occipital lobe – all vision Visual cortex –Association areas throughout
Two Cerebral Hemispheres Contralateral arrangement – the left hemisphere receives inputs from and controls the right side of the body and vice versa Work together on many functions but can also simultaneously carry out different functions with minimal duplication of effort Corpus callosum –Thick band of nerve fibers connects the two hemispheres
Functions of the Cortex
Primary Visual Cortex Receives and processes visual info from the eyes Visual Association Areas Interpret visual signals and recognize form, color, movement
Functions of the cortex Primary Auditory Cortex Receives/processes auditory information from the ears (sound) Auditory Association Areas Interpret sound Language comprehension (Wernicke’s area )
Primary Somatosensory cortex Processes sensory info (touch) from body Sensory Association Area Receives input from primary and secondary sensory cortex and is involved in complex associations
Motor and Sensory Cortex
Functions of the Cortex Primary Motor Cortex Origin of most of the corticospinal tract meaning, projects to the spine so it can send motor signals down to various body parts and tell them to move. Specific movements tend to be represented rather than specific muscles. Also projects to thalamus and basal ganglion Association Areas = Premotor Cortex In front of the motor strip Receives many of the same connections as the motor cortex but most of its outputs go to the motor cortex Responsible for more complex movements
Association Areas of the Cortex The ¾ of the cortex, across all four lobes not devoted to sensory or muscle activity. Interpret, integrate information processed by the sensory areas, link sensory inputs with stored memories In the frontal lobes enable judgment, planning, processing memories, inhibitions, and personality In parietal lobes enable mathematical and spatial reasoning In right temporal enable facial Recognition.
Association Areas More intelligent animals have increased “uncommitted” or association areas of the cortex.
Association Area Locations
Association Area Functions
Language cortical Areas Left Hemisphere Broca’s Area –Pierre Paul Broca –Language production Broca’s aphasia: - Language Comprehension unaffected but language production is impaired or lost speech non-fluent, labored, aware when they say something wrong
Language Cortical Areas Wernicke’s Area - Carl Wernicke - Understanding of written and spoken language Wernicke’s Aphasia - Language comprehension is affected - Speech retains normal rhythm and syntax but is largely meaningless
Specialization and Integration Complex human behaviors involve multiple specialized areas and association areas working together.
Our Divided Brain Corpus Callosum
Brain Lateralization One Brain or Two? Gazzaniga, M. S. (1967)
Left & Right Functions
Hemispheric Specialization Left brain Good with literal interpretations of language More active when a person is deliberating More “rational” Right Brain Making inferences about words and modulating speech to convey meaning Orchestrates sense of self Better with quick, intuitive responses Perceives objects better More involved in emotion, spatial reasoning
Divided Consciousness The Right hemisphere is nonverbal but it can still make itself understood
Split Brain Patients atch?v=aCv4K5aStdU With the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left visual field cannot.
Left hemisphere – language, logic, laughter –Logical, verbal, sequential –Positive emotions Right hemisphere – –Spatial, emotional intuition, music, “big picture” (People with damage to the left hemisphere may lose their ability to speak but not sing (a right hemisphere task). They can redevelop language by learning to sing everything they want to say!)
D D D D D D D D D DDDD D D D D D D D D DD 1.What is the large composite letter? H (right brain active, “big picture”) 2. What is the small component letter? D (left brain active)
Which face looks happier to you?
FORKSPOON When asked to SAY what they saw, they answer __________________ –(spoon) When asked to pick up what they saw with their left hand, they will pick up a ______. –(fork)
A split brain patient has a picture of a knife flashed to her left hemisphere and that of a fork to her right hemisphere. She will be able to A. identify the fork using her left hand. B. identify the knife using her left hand. C. identify the knife using either hand. D. identify the fork using either hand. Answer: A
Dr. J briefly flashed a picture of a key in the right visual field of a split-brain patient. The patient could probably A. verbally report that a key was seen B. write the word “key” using her left hand C. draw a picture of a key using the left hand D. none of the above
What will happen as a neurosurgeon sedates the entire right cerebral hemisphere of a patient who is asked to count aloud with both arms extended upward? A. her left arm will fall and she will become speechless B. her right arm will fall and she will become speechless C. her left arm will fall and she will continue counting D. her right arm will fall and she will continue counting
People should typically recognize familiar words more rapidly when spoken into their __________ ear. Answer: right People should typically recognize familiar melodies more rapidly when played into their ________ ear. Answer: left Note: Not all people have such simple separations between hemispheres. Women (more than men) tend to use both sides of their brain when interpreting language.
Unilateral Neglect After damage to the right hemisphere, some patients exhibit indifference to the left side of their world – “hemi-neglect” The neglect can be multimodal, affecting auditory, visual, somatosensory Related to the right side’s involvement in spatial reasoning and sense of self. Damage to the left side does not have this effect.
Theories of lateralization – Why? May increase neural capacity Dominance by one side prevents the simultaneous initiation of incompatible responses/actions May increase capacity for parallel processing in the two hemispheres –But then why do we display a consistent preference at the population level? Shouldn’t there be an equal ratio of left to right side preference?
Theories of Lateralization – How? Lateral birth position and neonatal head orientation preference are both predictors of handedness Lateral asymmetry in the uterine environment and maternal anatomy my lead to the left side of the uterus being more “favorable” for fetal positioning. –But then why would we have any lefties at all?
Handedness Lefties are more likely than righties to process language with either the right hemisphere or with both hemisphere. 96% of righties process language primarily with left hemisphere. Left-handedness is more common among musicians, mathematicians, pro baseball players, architects and artists. Do you think there is a connection?
Handedness In the past, left-handedness was stigmatized in our society and as children, lefties were “trained” to use their right hands. Because most things are made for righties, lefties are more susceptible to accidental injury. On average, lefties live 9 years than people who are right- handed
Handedness Given these facts about left-handedness as well as what you have learned about research methods, what do you make of this graph?
The Brain’s Plasticity Plasticity occurs during normal brain development but it is also the brain’s ability to modify itself after injury or loss of function –Phantom limb –Enhanced peripheral vision in deaf people The brain is sculpted by our genes and by a person’s environment and experiences Neural tissue reorganizes and in some cases regenerates (neurogenesis)
Plasticity – the brain’s capacity to reorganize Blind person’s sensory cortex for their fingers may expand. In blind people, the visual cortex is activated when they read Braille. In deaf people, some visual information is process in the temporal lobe. Hemispherectomy – removal of an entire hemisphere of cerebral cortex; if surgery performed when young, other hemisphere takes over
Plasticity Slow destruction of Broca’s area by tumors leaves speech relatively intact. Its function shifts to nearby areas.
domestic cats have… - thicker skulls and smaller brains - less cone photoreceptors in their retina than wild cats wild cats tend to have…. - a greater total density of ganglion cells in their retinas The total neuron number and volume of the lateral geniculate nucleus (LGN) is larger in wild cats than in the domestic cat The actual cell size of the neurons in the LGN is the same in both wild and domestic cats