Lecture 16Outline of Last Lecture I. Inside the spinal corda. Tractsb. 3 functional groups of somatic sensec. The pathways of the 3 functional groupsi. Dorsal column pathwayii. Spinothalmic pathwayiii. Spinocerebellar pathwayII. The Brain: Cerebral CortexOutline of Current LectureI.A. Other primary sensory areas of the cerebral cortexB. Architecture of the cerebral cortexC. Association areas of the cerebral cortexD. Voluntary motor output of the cerebral cortexii. The Telencephalona. Limbic lobeb. Basal ganglia III. Diencephalon a. Thalamusb. Hypothalamus IV. MesencephalonCurrent LectureA. Other primary sensory areas of the cerebral cortexa. Visual, auditory, balance, smell and taste information reach the cortex in similar was as the general somatic sensory informationi. Contain 3 orders of neurons (multi-neuron pathways) between the receptor and the cerebral cortexii. for all of the senses, the final relay nucleus is in the thalamusiii. also experience crossing overiv. most kinds of special sensory information remain highly organized throughout their path to the cortexB. architecture of the cerebral cortexa. the cerebral cortex is a layer of gray matter on the outer part of the telencephaloni. differs from most of the rest of the CNS, because elsewhere, white matter is on the outsideii. the structure here is gray-white-grayiii. the white matter of the cerebrum, just deep to the cortex contains many types of axons:1. axons projecting to the cerebral cortex from other parts of the brain and spinal cord2. axons projecting from the cerebral cortex to the rest of the CNS BIOL_315 1nd Edition3. axons that interconnect different regions of the cerebral cortexb. about 3 billion neurons in cerebral cortexc. Neuron cell bodies within the gray matter are arranged into 6 layers, all present in every lobe of the cortexi. but they vary in thickness, size and shapeii. using morphological differences, Brodmann divided the cerebral cortex into 47 regions across the surface of the brain = Brodmann areas1. only used anatomical evidence to define areas, not function2. later discovered that was pretty correct in functional organization because form often relates to functionC. Association areas of the cerebral cortexa. Association areas: stretches of the cerebral cortex not involved in primary sensory perception or motor control, lying between the primary sensory zonesi. make associations between different perceptionsii. the primary visual cortex is involved in recognizing and understanding what we see1. visual processing areas are so large, they take up much of the parietal and temporal lobesiii. interrelate different sensory modalities b. prefrontal lobes, carry out much of our higher mental functionsi. deep thought, logic, planning and organizationii. highest level of thinkingiii. much larger in humans than many other animalsiv. larger in adults than in children1. makes sense because the adults have greater capacity for understanding and self-control2. doesn’t reach full function until mid 20’s v. prefrontal lobotomy: surgery that cuts the fiber connections to the prefrontallobes and used to be used to relieve severe emotional disturbances vi. people with injured prefrontal lobe: difficulty concentrating for any period of time, no appreciation of the future consequences of their actionsD. Voluntary motor output of the cerebral cortexa. Inititiates and controls our conscious, or voluntary, movementsb. Primary motor area: really have to think about in order to do voluntary movementsc. This area occupies the precentral gyrus, Brodmann’s #4d. Originates from large pyramid shaped interneurons: pyramidal cellsi. The cell bodies of which are located in a deep cell layer of the cortical gray matterii. The axons of these neurons contribute to the pyramidal tract (corticospinal tract)1. Descends through the cerebral white matter, through the ventral part of the brain stem, and into the spinal cord, where these axons influence the motor neurons2. Most cross overe. Pyramidal cells are arranged according to the body regions which they move (somatotopy)f. Motor homunculus on the precentral gyrus i. Discovered during brain surgeries g. Cortical areas providing motor output to the hand and face are disproportionately large because we have the most delicate voluntary control of our fingers and facial muscles h. Premotor cortex: Brodmann’s #6, controls complex movements, planning and guiding our body parts through 3-D spaceI. The Telencephalon a. Limbic Lobei. Limbic lobe: extensive area, medial and basal parts of the cerebral hemisphere, ring shaped includes (see below) and relate to our emotions, damage to them – mood and motivational disorders, irrational fear, unusual sexual behavior, extreme aggression or rage.1. Cingulate gyrus2. Septal nuclei3. Dentate gyrus4. Parahippocampal gyrus5. Amygdalaii. Hippocampus: consolidates experiences into long-term memories1. Memory2. The “seahorse”iii. Amygdala: allows us to learn and remember fear, after something has terrified us1. “fear almond”iv. Limbic system: the limbic lobe of the telencephalon is closely related to some other parts of the nervous system (olfactory bulb, the hypothalamus, and some parts of the reticular formation), which all together comprise the visceral functions—and the two are interrelatedv. Septum: part of the embryonic brain, gives rise to some of the telencephalic parts of the limbic systemb. Basal Ganglia (= basal nuclei)i. Series of brain nuclei deep in the telencephalon, internal to the white matter ii. Consists of: putamen, caudate, globus pallidus, and amygdalaiii. Lies just lateral to the thalamus of the telencephalon iv. Corpus striatum: the basal ganglia minus the amygdala v. Teams up with the cerebral cortex to control body movementsvi. Plays a role in stopping, starting and regulating the intensity of voluntary movementsvii. Parkinson’s disease: malfunctioning of basal ganglia underregulate the intensity of movements  rigid movements along with shakes and tremorsviii. Control repetitive tasks and instinctive behaviors, habits, compulsions, and act as a stopwatchII. Diencephalona. Thalamusi. Egg shaped region of gray matterii. Brain nuclei lying next to the third ventricle iii. Function: relay station for information going to the cerebral cortex 1. Any part of the brain or spinal cord that communicates with the cerebral cortex relays its information through the thalamusiv. These axons synapse in the