Advanced movements

Two main points of sensory motor coordination

1. Graded activation and competitive goal selection

2. Sensorimotor transformation

What is competitive goal selection and how was it studied

Selecting goals for action

• monkeys shown different quality motion stimulus

• At 50% coherence in the stimulus the performance increases

• Monkeys preformed at chance at 5% coherence

• 25% and 50% - monkeys are drawing out quality from the stimulus

What is graded activation and what was found

Looking at posterior parietal cortex ( planning) activity due to their exposure of varying quality stimuli

• can infer backward the quality of stimuli the monkey was exposed to

• Stronger activity occurs the more likely your going to make that movement

• Stronger sense of what the good quality information from the environment that I need to pick out

What is sensorimotor transformation

Converting environmental information into actionable signal we can do something with

What is the path sensorimotor transformation follows

Reflex arc

What is the process of the sensorimotor transformation for reaching

• information coming in at primary visual cortex

• Will flow over the parietal cortex through different subsystems that help convert this signal

• Then the info moves to the premotor cortex ( dorsal part more responsible for reaching out)

• Then sends signal out to reach

What are the subsystems in the sensorimotor transformation for reaching

1. MDP - mediodorsal parietal area → helps us identify goal directed behaviour and helps us attune our spatial attention

2. MIP - medial inter-parietal area → planning and executing goal directed movements, integrates visual targets with motor targets, specifically arm and hand

What is the sensorimotor transformation process for grasping

• information comes from primary visual cortex but goes to the dorsal extra area

• AIP - anterior intramural sulcus - contains neurons that respond the shape, size and orientation of whatever your going to grasp

• End point is the same promotior are as reaching ( premotor cortex ) but now the ventral part

What is optic ataxia

Inaccuracy of visual guides movements

What is optic ataxia the disruption off

The ability to preform these sensorimotor transformations adequately

What is millers posting task and its results

2 components

• match - orientate something to the target

• Target - action orientated - posting something to the target

Damage to the dorsal ( where ) stream can match but not do target task

Damage to the ventral / temporal lobe - struggle to match but can do target task

What is double dissociation

Evidence that the parietal cortex helps the coordination of visual and position information and pre-motor areas

What is the supplementary motor system (SMA)

Essential for generating linked self-generated movements

What happens without the SMA

no longer able to preform well learned movements and rely on external cues to get things done

What is needed for producing cued and uncued movements

A functional association between the pre-motor cortex and supplementary motor cortex

What does deactivation of the SMA produce

Sever disruption of learned sequences

What Is an efference copy

When a signal leaves the motor cortex, a copy of it also goes through the cerebellum

What other signals does the cerebellum get

Signals on what the body is doing from the spinal cord

What does the cerebellum do with the multiple signals it gets

Compares the two and adjusts what you do to produce smooth motion

Cerebella neuronal circuits learn what

To make more accurate movement over time

What happens once the cerebellum hasn’t learned its role in different movement patterns

It establishes specific motor program for each learned movement

Why can’t ballistic movements deepened on sensory feedback for their control

Because they occur so rapidly

what can’t happen once a ballistic movements is activated

There is no way to modify its present course by sensory feedback

The cerebellum input process

• frontal, motor and parietal cortices communicate with a part of the brain called Pons (the bridge)

• The pons crosses the midline (with the signal ‘the efference copy’)

• Signal is communicating with the cerebella cortex

• The cerebella cortex is coordinating information of what you acc did - getting this from 3 separate parts

1. Inferior olive → provides info from senses

2. Spinal cord → what your body is doing rn

3. Vestibular nucleus → provides information about movement of your head, trunk, and limbs

Cerebellum output process

• cerebellum will communicate with deep cerebellum nuclei and send information back across the midline, back up to the primary motor, through the ventrolateral complex (thalamus), and premotor corticies

• Then to have the information be sent out to create a rapid correction of what you are doing

What does ataxia mean

Lack of order

What are symptoms of cerebella ataxia

• errors in range and direction of movement

• Uncontrolled or repetitive eye movement

• Unsteady gait

• Slurred speech

• Hypometria and response delays

• Dysdiaocho kinesia

  
  

What is hypometria and dysdiaocho kinesia

Hypometria - movements short of an intended goal

Dysdiadocho kinesia - impaired ability to preform rapid alternating movements

What is the cerebellum sensitive to

Ethanol found in alcohol

Cerebellum reliant aspects that field sobriety test include :

• walking in a line

• Touching tip of nose with eyes closed

What is the basal ganglian loop

Set of brain systems that control the amount of action/energy coming out of the thalamus to the cortex to generate movement

What is the cortex doing in the basal ganglian loop

Generating movement

• exciting striatum which suppresses the Globus pallidus and substania nigra pars reticular which suppress the thalamus

What is the thalamus doing in the basal ganglian loop

Constantly sending excitory signal to the cortex

What is the caudate and putamen within the basal ganglian loop

The receiving zone for the cortex

What is the substantia nigra pars compacts within the basal ganglian loop

The melanin (protective function), helping dopamine levels modulate the whole system

What is the globus pallidus and substantia nigra pars reticulata within the basal ganglian loop

The principle output of the basal ganglian loop

What is hypokinesia and an example of a hypikinetic condition

Leads to the slowing of movement

• Parkinson’s

What is an example of a hyperkinetic condition

Huntingtons

Symptoms of Parkinson’s

• resting tremor in limbs

• Muscle rigidity

• Akinesia

• Bradykinesia

• Micrographia

How to you get Parkinson’s

Damage to the D1 and D2 routes

• loss of 60-80% neurons

What does damage to the dopamine modulation in the SNc do ?

• results in the progressive loss of dopamine producing nerve cells

• Dopamine delivered to the striatum is significantly reduced through D1 and D2 routes

Symptoms of huntingtons

• motor and cognitive symptoms

• Affect whole body

• Intellectual deterioration, depression and occasionally psychoticism

• Chorea

Cause of huntingtons

Damage to the striatum - caudate and putamen

• Neuronal loss to medium spiny neuron’s (most abundant in striatum)

• Degeneration of the output neuron’s from striatum which reduces the inhibitory modulation of motor function

• Disruption to the link between the striatum and cerebral cortex

what are the pathways like for hypokinesia

• insufficient direct pathway output

• Excess indirect pathway output

What are the pathways like for hyperkinesis

• excess direct pathway output

• Insufficient indirect pathway output

What receptors is the Direct pathway in the basal ganglian loop reliant on?

D1 - dopamine receptors

What receptors is the indirect pathway in the basal ganglian loop reliant on

D2 - dopamine receptors

What is the process of the direct pathway in the basal ganglian loop

Cortex Stimulates the striatum - inhibits SNr and GPi (causing less inhibition of the thalamus)

• in which the thalamus then stimulates the cortex

• Cortex then stimulates the cortical spinal tract via upper motor neurones, lower motor neurones and then the muscles which then produce movement

What is the process of the indirect pathway in the basal ganglian loop

Cortex stimulates striatum, then inhibits the GPe (causing less inhibition of the STN)

STN then stimulates the SNr and GPi - they inhibit thalamus - stimulating the cortex less then

• cortex is now stimulating less upper motor neurones, lower motor neurones and therefore the muscles

• Therefore producing flaccid muscles and less movement