BEHAVIORAL NEUROSCIENCE 214 FINAL EXAM WITH VERIFIED SOLUTIONS|GUARANTEED SUCCESS

Name the "touch" receptors and the types of information they carry - Hapsis is the perception of fine touch and pressure. - The corpuscular receptors are fast adapting and send input to the brain to the somatosensory cortex - Proprioception is the perception of the location and movement of the body. - It monitors the muscles and movements and gives feedback. - It is a fast adapting receptor that sends input to the brain to the motor cortex What is the difference between a rapidly adapting and slowly adapting receptor? Draw a graph that illustrates the difference to a prolonged touch. - Rapidly adapting receptor is the body sensory receptor that responds briefly to the beginning and end of a stimulus on the body. - Rapid adapting afferent responds to onset and termination of skin deformation. It sends the message to stop. It responds to change. (e.g., moving your finger to push on your forearm and then pull away) - Hapsis and proprioception - Slowly adapting receptor is the body sensory receptor that responds as long as a sensory stimulus is on the body. It tracks the stimulus during the whole duration. It creates a response to sustained skin deformation. - Slow adapting afferent with early peak lowered response to sustained skin deformation (e.g., pushing a finger on your forearm) - Nociception Brainpower 0:03 / 0:15 Describe the anatomic pathways for touch and pain. Why is there a difference in how the information is wired? - The dorsal spinothalamic tract sends input to the brain. It carries haptic and proprioceptive information. Axons from the dorsal-root ganglion neurons enter the spinal cord and ascend ipsilaterally (same side) until they synapse in the dorsal column nuclei (base of brain). Axons from the dorsal column nuclei cross over to the opposite side of the brain and project up through the brainstem as part of a pathway called the medial lemniscus. Axons synapse with neurons located in the ventrolateral thalamus, which projects to the somatosensory cortex and motor cortex - The ventral spinothalamic tract sends output in order to respond to the pain. It carries nociceptive information. Axons from the dorsal-root ganglion neurons enter the spinal cord and cross over right away and synapse onto neurons on the contralateral side. Axons from the contralateral spinal cord then ascend to the brain where they join with other axons forming the medial lemniscus, eventually snapsing with neurons located in the ventrolateral nucleus of the thalamus. Neurons from the thalamus then project to the somatosensory cortex. - The difference is our body has to first receive a touch stimulus, sending an input of information to the brain. Once the brain receives the input, in order to respond it sends an output of pain perception. You need one to do the other. What is a somatosensory homunculus and what determines the extent of cortical representation for a given part of the skin? - The somatosensory homunculus is found on post central gyrus in the parietal lobe - It is a representation of the amount of cortex devoted to a particular dermatome - Larger surface areas reflect: -- Greater sensitivity -- Smaller receptive field sizes -- Types of skin/receptors -- Ecological significance of the body part According to the neurobiologists, what are the 3 levels of hierarchically organized motor control systems and what is the function of each level? - The spinal cord mediates reflexes and CPG. - The brain stem/cerebellum integrate motor commands from cortex and relays inputs from spinal cord. They have 2 parallel neuronal systems: Ventromedial tracts-posture/balance, and Dorsolateral tracts-discrete control of distal muscles (hand/eye). - The motor areas of the cerebral cortex initiate main commands for action and initiate sensory guidance of movements. The 3 cortex include: Primary motor cortex (M1 or Area 4), Premotor cortex, Supplementary motor cortex. What are the six categories that motor behavior may be classified in to? 1) Simple reflex - stretch, knee-jerk, startle, eye-blink 2) Posture & posture change - standing, sitting, balancing 3) Locomotion - walking, creeping, crawling, running, swimming, flying, hopping 4) Sensory orientation - head turn, touching, eye-fixation, sniffing, tasting 5) Species typical action patterns -- Ingestion - chewing, biting, drinking -- Courtship display - chasing, retreating, sniffing -- Escape & defense - hissing, submission posture -- Grooming - washing, preening, licking -- Gestures - grimacing, tail erection, squinting, tooth barring 6) Acquired skills - speech, tool use, dancing, driving Describe the differences between intrafusal and extrafusal muscle fibers. How do they work together to effect muscle movement? - Extrafusal are the outside muscles; they produce the muscle contraction (alpha motor neuron) - Intrafusal are active before the extrafusal; set limits to how the extrafusal fiber is going to react; "fine tunes" force of contraction (gamma motor neuron) - Gamma motor neurons set limits for the alpha motor neurons in which they react to Is there a "monosynaptic" reflex? Why or why not? - Monosynaptic reflex: sensory input coming in the dorsal root and the interneuron in the synapse releases through the ventral root in order to give a reaction to the sensory input. - How it occurs: -- Sensory organ receives a stimulus -- Nerve impulse -- The dorsal root (spinal) ganglion -- The posterior horn of spinal cord -- The anterior horn of spinal cord -- Cells of effector organ, such as skeletal muscle -- The final action of the reflex, such as a voluntary muscle contraction Why don't we fall down when we step on a tack? Draw a wiring diagram that illustrates this crossed extensor reflex response. - During the withdrawal reflex, the cross extensor reflex responses by other side of the body to compensate - It is accomplished through the action of inhibitory interneurons (Renshaw cells) Describe a motor disorder and its associated symptoms for the following elements of the motor system: neuromuscular junction, spinal cord, brain stem, cerebral cortex, basal ganglia, and cerebellum. - Myasthenia gravis is a blockade of neuromuscular junction; profound weakness in skeletal muscles beginning with head (drooping eyelids) and progressing to muscles involved in swallowing and respiration - It attacks acetylcholine receptors which is caused by the physostigmine preventing the action of acetylcholinesterase Define and provide evidence for equipotentiality and localization. - Equipotentiality states that all parts have an equal effect to create a behavior. -- In 1927, Karl Lashley, an anti-localizationalist, removed a big part of a rat's brain after learning the function of a t maze, in order to determine if the rat could still do the task. Lashley concluded that the rat was still able to complete the task. He concluded that because of equipotentiality learning must reside in the cortex. - Localization is a particular part of the brain that creates a specific behavior. -- In 1861, Paul Broca published the first widely accepted evidence of cortical localization. He associated damage to the frontal cortex of the left hemisphere and aphasia. It was then discovered that a part of the frontal lobe (broca's area) was linked to language and the formation of speech. List and describe the four major categories of biological explanations of behavior (after Tinbergen). How can Tinbergen's categories of biological explanations of behavior be applied to the study of a single behavior: birdsong? 4 explanations: - Physiological Explanations: examine the machinery that controls behavior (structure = function) - Ontogenetic Explanation: examine the development of a structure/behavior - Evolutionary Explanations: examine structure or behavior in terms of evolutionary history (e.g. piloerection: hair stands up on animal when threatened) - Functional Explanations: why a particular structure or behavior evolved (e.g. "fluffed fur traps warm oxygen near skin") 4 explanations applied to 'birdsong': - Physiological category: the testosterone production at adolescence causes morphological changes in the brains male songbirds (they sing to maintain their territory) - Ontogenetic Category: young males must learn the song of their species from older males. - Evolutionary Category: species have different songs so that members can differentiate. Closely related species have similar songs. - Functional Category: male sings mainly during breeding season and only at volumes that carry over his territory. Function is to improve his chance of mating. Give a brief history of the study of the brain by naming 10 contributors and their contributions to our understanding of brain function. - Thales believed that internal or naturalistic explanations of thought and action (soul) causes behavior. - Hippocrates, known as the Father of Medicine, believed in a holistic type of health and that the brain was the seat of intelligence. - Aristotle theorized that the brain was a cooling mechanism for the blood. - Herophilus and Erasistratus distinguished sensory nerves from motor nerves through conducting an experiment where they did dissections on living humans. - Galen performed animal experiments and identified "animal spirits" as nerve energy. - Descarte was a known dualist where he believed the pineal gland was "the seat of the soul." He conducted several experiments with doing dissections on dead humans and discovering animal spirits in the ventricles that are bi-directional. - Helmholtz was the first to measure the speed of a nerve impulse. His experiment consists of stimulating the nerve of a frog and then recording the resulting muscle contraction on a drum rotating at a constant speed. - In 1870, Fritsch and Hitzig discovered the "excitable cortex" and identified how is only in one particular part of the brain. They tested a dog with a drug that electrically stimulated it's brain in order to see the reaction of the dog's motor cortex. - David Ferrier perfected the lesion method by electrically stimulating the motor cortex by making focal lesions that affected isolated muscle groups, and verified the location and extent of lesions histologically. Describe the theory of natural selection as authored by Darwin and Wallace. What are the 3 general facts central to the theory. What are the major contributions of Darwin's theories? - Charles Darwin and Alfred Russell Wallace, independently brought history to the natural sciences. They introduced the idea that species were related. - The 3 general facts central to the theory are (1) individuals of species are not identical (2) some of the variation can be inherited (3) not all offspring survive. In "The Origin of Species by Means of Natural Selection" Darwin presented evidence that the forces of nature were blind agents of selection that either reduce or enhance the probability that a species will survive. What are the 3 nuclei that compose the basal ganglia? What is the major fiber tract that passes through the basal ganglia? - The caudate nucleus is connected to the lateral ventricle and structured with a tail. - The putamen is below the caudate, and the internal capsule splits the two. - The globus pallidus is a pale looking structure connected to the putamen below it. - The internal capsule is the major fiber tract that passes through the basal ganglia. What are the meninges? Describe the steps in cerebrospinal fluid circulation. What are the two main functions of the CSF? - Meninges are 3 layers of protective tissue the dura mater, arachnoid, and pia mater -- they encase the brain and spinal cord. (1) the CSF flows into the third ventricle and down the aqueduct of Sylvius and into the fourth ventricle. (2) from the fourth ventricle it passes through the foramina and into the subarachnoid space surrounding the brain and spinal cord. (3) it is finally absorbed through blood vessels into the bloodstream. - 2 main functions of the CSF is to protect the brain and spinal cord from trauma, and to supply nutrients to the nervous system tissue. Describe the major fiber tracts and the direction of information associated with each respective "information highway". - Corpus callosum: connects the two hemispheres (left to right) in order to pass along information. - Corona radiata: carries information front to back within each hemisphere (ipsilateral - same side) from the brainstem to the cerebral cortex. - Internal capsule: carries information (up and down in and out) of brain and splits up the putamen and globus pallidus from the caudate nucleus (within the basal ganglia structure). What are the 3 components that make up the peripheral nervous system and how do they differ from each other? - Cranial nerves connect directly to the brain. - Spinal nerves connect directly to the spinal cord. - Autonomic nervous system originates from the brain and spinal cord; regulates smooth muscle, cardiac muscle and glands -- Parasympathetic: part of the autonomic nervous system; arouses the body for action, such as meditating the involuntary fight-or-flight response to alarm by increasing heart rate and blood pressure. -- Sympathetic: part of the autonomic nervous system; acts in opposition to the sympathetic division - for example, preparing the body to rest and digest by reversing the alarm response or stimulating digestion. Draw a cross-section through the spinal cord (including the spinal nerve, dorsal root ganglia), label the dorsal and ventral horns and indicate which are sensory and which are motor. Also label the white and gray matter and explain the difference in color. (draw) What is the principle of proper mass? How does this principle relate to brain size and behavioral complexity? Give some examples. - The principle of proper mass states that the amount of neural tissue responsible for a particular function is equivalent to the amount of processing that the function requires. - For example, as behaviors become more complex, so do the brains that generate them. You need just enough neurons to control the behavior you have. We follow the general rule that claims the bigger the body the bigger the brain, and this results in more neurons. In the 19th and 20th century it was believed that the parts of your brain you used most for the behaviors you had a bigger part. In order to do a certain function the physical effort needs to equal the amount of internal energy your brain is using. Outline the "encephalons" with their associated CSF landmarks. - Telencephalon: Forebrain; lateral ventricles, cerebral cortex, basal ganglia, limbic system - Diencephalon: forebrain; Thalamus, Hypothalamus, Pituitary gland - Mesencephalon: midbrain; aqueduct of sylvius, tectum (superior and inferior colliculus), tegmentum - Metencephalon: hindbrain; pons, medulla oblongata, cerebellum, 4th ventricle - Myelencephalon: Hindbrain; medulla oblongata - responsible for many "automatic functions" like breathing, heart beat/speed, etc. *Tel di mes met my* Describe a scenario for encephalization that occurred during the evolution of our primate ancestors. Include a treatment of the niche factors that shaped the expression of sensory and motor abilities. - 400 million years ago the Day Niche had an incredibly small brain due to the fact that they weren't needing to do a wide variety of things like we are today. - Within a 100 million years external activation had evolved and these niches needed sunlight as a necessity to warm their bodies. They needed this in order to have strength and energy to get food and mate. List and describe the six characteristics shared by all vertebrate nervous systems. What makes a primate a primate? List 6 characteristics that primates share. 6 characteristics: - Common developmental origin (from neural tube) - Bilateral symmetry (more or less) - Segmentation (pairs of spinal nerves at each level of spinal cord) - Hierarchical Control (CNS over pns) - Separate Systems (CNS is separate from pns) - Localization of function (certain functions controlled by certain locations in CNS) In primates: - The big toe on the foot is opposable, and hands are prehensile - both can be used for grasping - There are flat nails on the hand and feet in most species, instead of claws, and there are sensitive tactile pads with "fingerprints" on fingers and toes - Locomotion is hindlimb dominated, with the center of gravity near the hips rather than the shoulders - Unspecialized olfactory apparatus that is reduced in diurnal primates - The visual sense is highly developed. The eyes are large and frontally placed on the head - The brain is large compared with the brains of similarly sized mammals, and it has a number of unique anatomical features What are the consequences of encephalization? - Biological: larger brains are metabolically expensive - Ecological: need more food; and/or food that is richer in nutrients - Sociological: new technologies that are by-products of our big brains may not be in our species best interest