CONTROLLING THE BODY Flashcards
1
Q
What is the role of the intraparietal sulcus (IPS) in parietal orientation?
A
- The IPS = useful landmark for parietal orientation
- In monkeys > area 5 lies above IPS (superior parietal lobule) > area 7 lies below it (inferior parietal lobule)
- In humans > both areas 5 & 7 are positioned above IPS = forming superior parietal lobule
- The orientation of sulcus differs between the two species = variations in definition of inferior & superior parietal lobes
2
Q
what is intraparietal sulcus?
A
- parietal lobe
- crucial for sensory-motor integration, spatial awareness, & cognitive functions > e.g. visuospatial processing
3
Q
what do cortical projections connect to, to control action?
A
- sensory areas to parietal areas to premotor then primary motor areas
- Basal Ganglia > Connections to basal ganglia contribute to planning & execution of movements + control of muscle tone
- Cerebellum > receives cortical input & is crucial for coordination, precision, & the accurate timing of movements
4
Q
What regions and functions are associated with the parietal lobes?
A
- parietal lobes = receive & integrate sensory info > act as termination point for dorsal visual stream
- They abut & connect with somatosensory cortex > projecting to prefrontal, premotor, and primary motor areas of frontal lobes
- Damage to the superior parietal lobes, = optic ataxia > impacting visually-guided movements.
5
Q
How is the motor homunculus used to illustrate somatotopic representation in M1?
A
- Electrical stimulation studies suggest diff regions of the primary motor cortex (M1) map onto specific areas of the body
- motor homunculus > illustrates distorted relationship between cortex & body = highlighting functional importance of areas > e.g. hands & lips.
6
Q
what do the pathways between cerebral cortex and cerebellum imply that information flows?
A
- from cereal cortex to cerebellar cortex to cerebellar nuclei back to cerebral cortex
7
Q
what is the primary motor cortex?
A
- also known as M1 or area 4
- plays a fundamental role in planning, initiation, & execution of voluntary movements
- located > precentral gyrus of frontal lobe
- motor homunculus = rep in brain’s primary motor cortex (M1) > maps body parts to specific regions based on the complexity of movement control > It illustrates a somatotopic organization, emphasising finer motor control in areas like the hands & face
- damage = hemiplegia > impairment of motor movement > complete paralysis
8
Q
what is the lateral corticospinal tract?
A
- direct control from M1
- role = fine control of voluntary movements, esp those involving skilled & precise motor activities.
- cutting the pyramidal tract impairs fine finger control
9
Q
what is muscular activation?
A
- skeletal muscles that support voluntary movement
- can be generated in spinal cord w/o direct involvement of cortex in certain reflex actions > Reflexes are rapid, automatic responses to stimuli that involve the spinal cord & peripheral nerves w/o need for higher brain centers, e.g. cortex.
10
Q
what is M1 somatotopy?
A
- organisation of M1 in way that reflects the spatial arrangement of body parts
- In motor homunculus representation of M1 > diff body parts are mapped to specific regions of cortex based on the amt of motor cortex devoted to their control e.g. rep of hands & face = occupy more cortical space than other body parts cos they require more precise control & have greater sensitivity.
- best described= fractured and distorted
11
Q
Why are frames of reference important in motor control?
A
- Frames of reference help brain coordinate movements > by aligning diff reference frames > e.g. vision & body-centered frames.
12
Q
How are receptive fields and response tuning interconnected?
A
- Response tuning enhances a neuron’s selectivity within receptive fields > optimising its ability to detect specific features.
13
Q
what are multiple coordinate systems?
A
- some premotor cells have visual receptive fields aligned with limb-centered receptive fields = certain neurons in premotor areas can integrate visual info w/ respect to position or movement of specific body parts (limb-centered) > creating a coordinated representation for planning and executing motor actions.
14
Q
what are the different types of receptive fields?
A
- Vision> Retinal Receptive Fields: Neurons in retina > sensitive to light falling on specific regions of the visual field > Visual Cortex Receptive Fields = Neurons in visual cortex respond to specific features in the visual field
- Somatosensation: Neurons in skin respond to stimuli in specific areas
- Motor Control > Motor Neuron Receptive Fields = Neurons in motor cortex or spinal cord respond to specific movements or positions of body parts
- Head-centered receptive fields = neural responses based on position of stimuli relative to head’s orientation > coordinating sensory info & motor planning > esp during head movements.
15
Q
what are the differences in reaching vs grasping in our cortical system?
A
- Grasping = Parietal areas > e.g. AIP & rPMv identify & categorise objects for grasping, object centred ( determining an opposition space between object & hand)
- Reaching = egocentric (where relative to me), PRR
- Primary motor cortex (M1) plans & executes reaching & grasping movements, w/ diff regions representing body parts
- Coordination between parietal & motor areas is crucial for accurate & visually guided grasping.
16
Q
what is the specialised cortical circuit for grasping?
A
- areas e.g. AIP & rPMv
- involves projections from dorsal visual areas to AIP (anterior intraparietal area) & then to ventral premotor cortex (rPMv - rostral ventral premotor area)
- This connectivity = integration of visual info about objects in environment with motor planning & execution of grasping actions
17
Q
What is the AIP - rPMv grasp circuit, and what functions do areas AIP and rPMv serve?
A
- neural pathways connecting anterior intraparietal area (AIP) to the rostral ventral premotor area (rPMv) > transforms visual info about objects into motor plans for grasping movements
- Neurons in AIP respond to object features, & their activity is linked to motor control of grasping in rPMv, = visually guided reaching & grasping
- Lesions in these areas = impair grasping behavior > highlighting role in visually-guided grasping
18
Q
Describe the non-primary motor areas in the frontal lobe and their connectivity with the parietal lobes.
A
- frontal lobe contains non-primary motor areas > inc: premotor area (PMA), supplementary motor area (SMA), & cingulate motor areas
- These areas receive substantial input from parietal lobes > forming pathways involved in tasks like reaching, grasping, + eye movements.
19
Q
How does primary motor cortex (M1) contribute to motor control, and what are the descending motor tracts?
A
- M1 > situated anterior to central sulcus = motor control > receives input from various frontal motor areas & is connected to primary somatosensory cortex
- Descending motor tracts > e.g. corticospinal & corticobulbar tracts > originate in cortex = controlling muscle activity.
20
Q
Explain the anatomy and connectivity of the basal ganglia and its role in motor control.
A
- basal ganglia > subcortical nuclei deep within brain = receive input from motor cortical areas & project internally
- outputs to the cortex via the thalamus, forming closed loops
- It plays a role in motor control, muscle tone, and posture.
21
Q
Describe cerebellum’s anatomy, connectivity, and its relationship with the cortex.
A
- Cerebellum > located behind spinal cord > receives input from spinal cord, vestibular nucleus, and cortex
- Output returns to the cortex via the thalamus = contributing to motor coordination.
22
Q
How does the brain handle coordinate transformations and receptive fields, particularly in the parietal lobes?
A
- Parietal cortex > manages coordinate transformations, > representing stimuli in various coordinate systems for action planning
23
Q
How is somatotopic representation organised in primary motor cortex (M1), and what controversies exist regarding M1’s body representation?
A
- M1 = somatotopic representation > mapping body parts to specific regions
- Controversies > abt exact nature of M1’s body representation
24
Q
How does M1 encode information related to force, direction, and population codes during movement?
A
- M1 neural activity > reflects force exertion & shows preferences for specific movement directions = accurate hand movement determination through population coding
25
How does the brain translate between abstract codes and muscle activity, particularly in M1?
- M1> converts spatial representations of movements into muscle commands = execution of specific actions
- Muscles control body parts by adjusting joint angles = translation of spatial representations into muscle commands
26
What role do internal models play in motor control, and how does the cerebellum contribute to rapid movements?
- Internal models > inc > forward dynamic & sensory/output models = crucial in motor control
- cerebellum holds internal models essential for accurate rapid movements.
27
what is schematic of closed loop control and what are its problems?
- idea that you guide an action by comparing where you are now to where you are to be.
- command signal > driven by error between current state and target state
- problem: takes time for sensory signal to be processed, unless control proceeds > using intermittent strategy > delays = overcompensation
28
what are internal models in movement control?
- forward models: take what you are intending to do to predict what's going to happen (forward dynamic model) = guess what we would experience in feedback in response (forward sensory model) = build form of closed loop control w/ no problems w/ feedback delays > brain anticipate & adjust movements based on expected outcomes
