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BMSC335 Lecture 3 Week 1
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- 1In terms of signaling to the brain, what does the term 'afferent' mean?Afferent: The direction a signal travels when it is travelling into the brain.
- 2In terms of signaling to the brain, what does the term 'efferent' mean?Efferent: The direction a signal is travelling in when it is leaving the brain.
- 3What are the two main pathways in the CNS for response?1. Corticospinal (also known as Pyramidal) tract.
2. Extrapyramidal System. - 4What is another name for the Corticospinal tract?The Pyramidal tract.
- 5Is the Extrapyramidal system involved in A) Sensory input or B) Response outputB. Response output.
- 6Is the Corticospinal tract involved in A) Sensory input or B) Response output?B. Response output.
- 7In the Somatosensory pathway, how many 'orders' or groups of Neurons are there?Four.
- 8What are 'First Order Neurons'?- Primary afferents whose peripheral endings for the sensory receptors (or receive inputs from them).
- Transmit information from environment to CNS, and have their cell bodies in the dorsal root (or cranial nerve) ganglia. - 9What are 'Second Order Neurons'?- Neurons located in the spinal cord or brainstem.
- Transmit information from the first order neurons to the Thalamus (usually contralateral Thalamus). - 10What are 'Third Order Neurons'?- Neurons that transmit information from one of the sensory nuclei in the Thalamus to a sensory region of the cerebral cortex.
- 11What are 'Fourth Order Neurons'?- Neurons located in the sensory regions of the Cerebral Cortex.
- May synapse with higher order neurons (higher processing). - 12Where are 'Higher Order Neurons' located in relation to 'Fourth Order Neurons'?- Higher order neurons can be located in either the same, or other, cerebral cortical regions.
- 13What does Dr. Kivell mean when she refers to the 'spatial organisation' of the CNS?- All nerve tracts in the spinal cord are arranged in specific spatial conformations.
- Deep touch and vibration are sensed by tracts running through the dorsal surface of your SC.
- Pain/Temperature/Light touch/Voluntary motion are all sensed or actioned by tracts running through the ventral surface of your SC. - 14What is another name for the Dorsal Column Pathway?Medial Lemniscus Pathway.
- 15What happens to reaction output when the Dorsal column pathway (in Dorsal surface of SC) is damaged?- Impaired muscle control.
- Loss of sensation of vibration.
- Loss of discriminatory touch below the level of the lesion. - 16How can lesions of the somatosensory pathways be used in a therapeutic setting?Anterolateral cordotomy (surgical lesion of the spinothalamic tract) can be used to reduce pain in certain patients.
- 17How might a clinician or neurologist assess a patient for spine damage?By prodding/poking him or her in various places around the body to determine sensation/ability to feel pain.
- 18Is it common to suffer a lesion that affects only one tract?No. More common to suffer a lesion such as hemisection of the cord which leads to the loss of fine touch/vibration and loss of crude touch/pain and temperature.
- 19Name four major differences between the Anterolateral Pathway and the Dorsal Column Pathway:1. Velocities of transmission are slower in the ALP.
2. Poor spatial localization in ALP.
3. Less graduations of strength.
4. Crude system compared to dorsal column pathway. - 20Do any of the sensory pathways travel directly from receptor to the cortex?No.
- 21What part of the brain is also known as the 'gateway to the cortex'?The Thalamus.
- 22What type of nuclei transmit signals from rest of body to the Cortex?The Thalamus' relay nuclei.
- 23What role, other than transmission, might the relay nuclei play in the transmission of signal to and from the Cortex?- Attenuates/regulates signals
- Increases or decreases sensory input as necessary (most important sensory input emphasized).
- Reduces irrelevant activity and sharpens contrast. - 24Where is the Somatic Sensory Cortex located?In the postcentral gyrus.
- 25Is each part of the body equally represented by a portion of the Somatic Sensory cortex?- No, the representation is unequal.
- Lips have the greatest area of representation followed by the face and thumb.
- Trunk and lower body have the least area. - 26How many 'areas' make up the Somatosensory Cortex?2. Somatosensory Area I & II
- 27Are responses stimulated in the Somatosensory cortex as the same side as the stimulated receptor?No. Opposite side. The body feels pain on one side, it stimulates the opposing side of the brain.
- 28What is a Homonculus?- Diagrammatic representation of the amounts of the cortex that are dedicated to controlling/sensing certain parts of your body.
- 29How many layers are there in the cortex?6.
- 30Briefly describe the cellular organization of the cortex:- 6 layers, with neurons in the layers arranged into columns.
- Each column serves a specific sensory modality.
- Different columns are interspersed among each-other (interwoven complexity of the brain) - 31List some of the symptoms a patient might experience if his or her Somatic Area I was destroyed:- Loss of discrete localization ability.
- Inability to judge the degree of pressure.
- Inability to determine the weight of an object.
- Inability to determine the shape or form of objects (astereognosis).
- Inability to judge texture. - 32What is astereognosis?The inability to determine the shape or form of objects.
- 33Where are the Somatic Association Areas located?Behind the somatic sensory cortex in the parietal area of the cortex.
- 34Where do Somatic Association Areas receive input from?- Sensory cortex.
- Ventrobasal nuclei of the Thalamus.
- Visual and auditory cortex. - 35What is the primary function of the Somatic Association Areas?To decipher sensory meaning.
- 36What happens when a patient loses their Somatic Association Areas?Inability to recognize complex objects or loss of self.
- 37How did Neuroscientists come to understand the importance of the Somatic Association Areas in interpreting input information?A WW1 soldier was wounded by a bullet which pierced his dorsolateral parietal lobe and exited through the right ventrolateral parietal lobe - resulting in a visualspatial deficit. He was unable to copy images exactly - ignoring one half of the image completely.
- 38What are corticofugal fibres?- Fibres that run from the cortex to the sensory relay areas of the Thalamus, Medulla and SC.
- Inhibitory fibres which can inhibit sensory input. - 39What are the main functions of Corticofugal Fibers?- Decrease the spread of a signal
- Sharpen the degree of contrast and adjust the sensitivity of the system. - 40What neurological condition is associated with the malfunction or damage of Corticofugal fibers?Autism.
- 41What parts of brain provide output to be relayed through the Corticospinal Tract?- Primary Motor Cortex
- Supplementary and Pre-motor Cortex
- Somatosensory Cortex - 42At what level does the Corticospinal Tract cross over?Crosses over at level of Medulla.
- 43Which system controls sensory output directly: Corticospinal or Extrapyramidal?Corticospinal.
- 44What is the main function of the Corticospinal tract?To carry the motor commands that drive voluntary movement.
- 45What muscles does the lateral Corticospinal tract control: distal or proximal?Distal muscles.
- 46What muscles does the anteruor Corticospinal tract control: distal or proximal?Proximal.
- 47What is the major symptom of a damaged Corticospinal tract?Permanent loss of fine control of the extremities.
- 48What parts of the brain contribute output to the Extrapyramidal system?- Basal Ganglia.
- Reticular formation (Brainstem).
- Vestibular Nuclei (BS).
- Red Nuclei (BS) - 49What are the 4 Nuclei of the Basal Ganglia?1. Striatum (caudate and putamen)
2. Globus Pallidus.
3. Substantia nigra.
4. Subthalamus. - 50What is the primary purpose of the Basal Ganglia?To link the Thalamus to the Cerebral Cortex.
- 51What is the Caudate circuit?- Circuit of signaling formed by the Caudate which extends into all lobes of the Cortex and receives a large input from association areas of the Cortex.
- Mostly projects to the Globus Pallidus (no fibers to subthalamus or substantia nigra).
- Believed to play a role in cognitive control of motor functions (thinking about moving). - 52What are the symptoms of lesions on the Globus Pallidus?Athetosis - spontaneous writing movements of the hand, arm, neck, and face.
- 53What are the symptoms of lesions on the Putamen?Chorea - flicking movements of the hands, face and shoulders.
- 54What are the symptoms of lesions on the Substantia Nigra?- Parkinson's Disease - rigidity, tremor and akinesia.
- Loss of dopaminergic input from substantia nigra to the caudate and putamen. - 55What are the symptoms of lesions on the Subthalamus?Hemisballismus - sudden flailing movements of the entire limb.
- 56What are the symptoms of lesions on the Caudate Nucleus or Putamen?Huntington's Disease - loss of GABA containing neurons to Globus Pallidus and Substantia Nigra.
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- Bachelors Degree BMSC335: Advanced Physiology Fichas sobre BMSC335 Lecture 3 Week 1, creado por Maddie McIntyre el 02/03/2016.
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- Maddie McIntyre
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