Lecture 5: perceptual-motor functioning

Question 1

Perception sensory systems

Answer 1

1. Vision = seeing
2. Olfaction = smelling
3. Gustation = tasting
4. Audiation = hearing
5. Somatosensory = feeling
6. Vestibular = balancing
7. Proprioception = where in the space your body parts are

Question 2

Token test

Answer 2

Verbal test where a person had to describe the color, shape and size of the token. Can be used to measure:
- Language problems
- Perception problems
- Motor function problems

Question 3

The visual system

Answer 3

• The dorsal pathway (WHERE) (top of the brain): spatial location and action. Involves visually guided behaviour. Is highly sensitive for temporal frequencies and motion and only had a very short-term storage. It’s relatively fast and uses low consciousness. It’s viewer-centred or ego-centric.
• The ventral pathway (WHAT) (bottom of the brain): recognition/identification of objects. Is highly sensitive for spatial frequencies and details and has a long-term storage. It’s relatively slow process and uses high consciousness. It’s allocentric or object-centered.

Question 4

Disorders of the visual system

Answer 4

Can be divided into lower-order and higher-order deficits:
- Lower-order deficits: elementary visual impairments related to damage within the visual pathways or V1.
- Higher-order deficits: impairments in visual perception often related to damage in the secondary visual cortical areas.

Question 5

Higher-order visual disorders

Answer 5

• Achromatopsia: inability to see colour due to damage in the v4.
• Akinetopsia: inability to see motion due to damage in the V5.
• Agnosias: inability to know, name, identify and extract meaning from perceptual stimuli, despite nothing being wrong with their eyes. It’s a disruption in the pathway that processes specific stimuli: the sensory perception of a perceived stimulus is disconnected from memories with the perceived stimulus.

Question 6

Visual agnosia

Answer 6

Inability to recognize objects with an intact visual function. Is the most common form of agnosia and can be classified into 2 categories:
1. Apperceptive agnosia: inability to integrate incoming information into an image and to match or discriminate between visually presented objects. Not being able to draw it, but being able to name it.
2. Associative agnosia: inability to associate an image with memories / knowledge. Ability to link the image to stored information in the brain about an object. Being able to draw it but not to name it (they don’t know what it is but they can copy it).

Question 7

Other forms of visual agnosia

Answer 7

• Colour agnosia: inability to recognise colours.
• Object agnosia: inability to recognise objects.
• Simultanagnosia: inability to perceive overall meaning of the whole image or shape, but being able to recognise individual elements.
• Prosopagnosia: inability to recognise faces.

Question 8

Auditory agnosia

Answer 8

Inability to recognise spoken words or environmental sounds, despite preserved hearing. Types:
- Apperceptive: inability to repeat a word/sound.
- Associative: being able to repeat a word, but inability to match different sounds/words into the same categories.

Question 9

Tactile agnosia

Answer 9

Inability to recognise an object through touch, despite the physical ability to manipulate the object. Patients still recognise tactile characteristics (heavy, round). It’s caused by unilateral brain damage, which causes the contralateral hand to be agnostic.

Question 10

Asomatognosia

Answer 10

Feeling that part of one’s body are missing, fading or have dissapeared. It’s caused by damage in the righ posterior parietal cortex or motor cortex and usually caused by a stroke.

Question 11

Sensory deceptions

Answer 11

• Hallucinations: perceiving something that isn’t there. Can result from medication or brain damage.
• Illusions: misinterpretation of real stimuli. Visual illusions are most common but there are also sound illutions etc.

Question 12

Movement hierarchy

Answer 12

1. Reflexes: fixed, automated movements.
2. Automated movements: can be postural (to maintain an upright position) and rhythmic (like walking).
3. Voluntary movements: intentional goal directed behaviour (the reflexes and automated movements make sure that this is performed in the right way).

Question 13

Motor pathways

Answer 13

• The M1: primary motor cortex.
• Corticospinal pathways
• Brainstem pathways

Question 14

Medial vs. lateral motor systems

Answer 14

• Medial motor system: controls movements that are guided by internal cues. Lesions in this area interfere with control of movements, which can lead to over-automatic behaviour of a-kinetic movements (no spontaneous movements at all).
• Lateral motor system: controls movements that are guided by external cues. Lesions in this area interfere with externally cued movements (like raising your arm in response to a cue.

Question 15

Other motor areas

Answer 15

• Cerebellum: balance, coordination, precision and timing.
• Basal ganglia: initiating and maintaining movements.

Question 16

Circuitry of the basal ganglia

Answer 16

There are 2 pathways that modulate cortical activity and movement:
1. Direct pathway: excitatory
2. Indirect pathway: inhibitory

Question 17

Parkinson’s disease

Answer 17

Neurodegenerative disorder with loss of dopamine cells in the substantia nigra. This leads to reduction of dopamine levels and causes the indirect inhibitory pathway to become more active, leading people to have:
- Motor symptoms: tremor, slow movement, stiffness and loss of balance.
- Non-motor movements: loss of sense, sleep problems, constipation, depression, daytime sleepiness, hallucinations, drop in blood pressure, cognitive problems.

Question 18

Huntington’s disease

Answer 18

Neurodegenerative disorder caused by a dominant genetic mutation that is toxic to the brain. Patients display involuntary rhythmic movements (chorea). There is an overstimulation of the motor drive. The indirect inhibitory pathway is affected, which leads to:
- Twitching movements
- Difficulty with self-control and thoughts
- Difficulty in movement and behaviour.

Question 19

Difference between Parkinson’s and Huntington’s

Answer 19

Both are basal ganglia-related disorders, but in Huntington’s there is an overstimulation of the motor drive, while in Parkinson’s there is an understimulation of the motor drive.

Question 20

Praxis system

Answer 20

Motor performance and skills are part of the praxis system. The praxis system regulates the ability to interact succesfully with the physical environment, to plan, organise and carry out a sequence of unfamiliar actions and to do what one needs and wants to do. This consists of 2 components:
1. Ideation: having the right idea about what needs to be done.
2. Production: executing the task.

Question 21

Apraxia

Answer 21

Deficits in either one of the 2 components of the Praxis:
- Ideational Apraxia: having no clear concept of what to do. This leads to inappropriate use of objects and difficulty with multi step tasks and manipulating objects. Leads to clumsy behaviour.
- Ideomotor Apraxia: intact understanding of what the task requires and ability to verbalise this, but loss of acces to the kinetic/motor memory on how to produce and mimic movement.

Question 22

Cerebral palsy

Answer 22

Cerebral = brain
Palsy = Paralysis

Caused by prenatal, perinatal or postnatal brain damage. There are different regions of damage that cause different symptoms:
- Cerebral cortex: stiff muscles.
- Basal ganglia: uncontrollable movements.
- Cerebellum: poor balance and coordination.
- Multiple areas of the brain: mixed types.

Question 23

Manual motor measures

Answer 23

• Muscle strength: hand dynamometer.
• Motor speed: computerised finger tapping test.
• Fine motor skills: computerised archimedes spiral test.
• Coordination: Purdue pegboard test.
• Speed: gait walking course.
• Balance: Romberg balance test.