4722365
Description
Flashcards by Maddie McIntyre, updated more than 1 year ago
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Created by Maddie McIntyre
over 8 years ago
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| Question | Answer |
| In 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. |
| In 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. |
| What are the two main pathways in the CNS for response? | 1. Corticospinal (also known as Pyramidal) tract. 2. Extrapyramidal System. |
| What is another name for the Corticospinal tract? | The Pyramidal tract. |
| Is the Extrapyramidal system involved in A) Sensory input or B) Response output | B. Response output. |
| Is the Corticospinal tract involved in A) Sensory input or B) Response output? | B. Response output. |
| In the Somatosensory pathway, how many 'orders' or groups of Neurons are there? | Four. |
| What 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. |
| What 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). |
| What 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. |
| What are 'Fourth Order Neurons'? | - Neurons located in the sensory regions of the Cerebral Cortex. - May synapse with higher order neurons (higher processing). |
| Where 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. |
| What 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. |
| What is another name for the Dorsal Column Pathway? | Medial Lemniscus Pathway. |
| What 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. |
| How 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. |
| How 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. |
| Is 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. |
| Name 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. |
| Do any of the sensory pathways travel directly from receptor to the cortex? | No. |
| What part of the brain is also known as the 'gateway to the cortex'? | The Thalamus. |
| What type of nuclei transmit signals from rest of body to the Cortex? | The Thalamus' relay nuclei. |
| What 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. |
| Where is the Somatic Sensory Cortex located? | In the postcentral gyrus. |
| Is 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. |
| How many 'areas' make up the Somatosensory Cortex? | 2. Somatosensory Area I & II |
| Are 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. |
| What is a Homonculus? | - Diagrammatic representation of the amounts of the cortex that are dedicated to controlling/sensing certain parts of your body. |
| How many layers are there in the cortex? | 6. |
| Briefly 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) |
| List 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. |
| What is astereognosis? | The inability to determine the shape or form of objects. |
| Where are the Somatic Association Areas located? | Behind the somatic sensory cortex in the parietal area of the cortex. |
| Where do Somatic Association Areas receive input from? | - Sensory cortex. - Ventrobasal nuclei of the Thalamus. - Visual and auditory cortex. |
| What is the primary function of the Somatic Association Areas? | To decipher sensory meaning. |
| What happens when a patient loses their Somatic Association Areas? | Inability to recognize complex objects or loss of self. |
| How 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. |
| What 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. |
| What 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. |
| What neurological condition is associated with the malfunction or damage of Corticofugal fibers? | Autism. |
| What parts of brain provide output to be relayed through the Corticospinal Tract? | - Primary Motor Cortex - Supplementary and Pre-motor Cortex - Somatosensory Cortex |
| At what level does the Corticospinal Tract cross over? | Crosses over at level of Medulla. |
| Which system controls sensory output directly: Corticospinal or Extrapyramidal? | Corticospinal. |
| What is the main function of the Corticospinal tract? | To carry the motor commands that drive voluntary movement. |
| What muscles does the lateral Corticospinal tract control: distal or proximal? | Distal muscles. |
| What muscles does the anteruor Corticospinal tract control: distal or proximal? | Proximal. |
| What is the major symptom of a damaged Corticospinal tract? | Permanent loss of fine control of the extremities. |
| What parts of the brain contribute output to the Extrapyramidal system? | - Basal Ganglia. - Reticular formation (Brainstem). - Vestibular Nuclei (BS). - Red Nuclei (BS) |
| What are the 4 Nuclei of the Basal Ganglia? | 1. Striatum (caudate and putamen) 2. Globus Pallidus. 3. Substantia nigra. 4. Subthalamus. |
| What is the primary purpose of the Basal Ganglia? | To link the Thalamus to the Cerebral Cortex. |
| What 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). |
| What are the symptoms of lesions on the Globus Pallidus? | Athetosis - spontaneous writing movements of the hand, arm, neck, and face. |
| What are the symptoms of lesions on the Putamen? | Chorea - flicking movements of the hands, face and shoulders. |
| What 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. |
| What are the symptoms of lesions on the Subthalamus? | Hemisballismus - sudden flailing movements of the entire limb. |
| What 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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