Interesting Mind Dysfunctions

SPEECH

Aphasias Discorders of speech production and understanding. Severe aphasia is when the LH frontal lobe in the motor cortex region is damaged, because it’s a crucial area for control of motor actions. The flow of information goes from the primary visual area > Wernicke’s area > Broca’s area.

i. Broca’s Aphasia Speech lacks gramattical structure and functional words such as “and”, “in”, “here”. Almost entirely concrete nouns and verbs. Eg. ‘pot … stand… fall down… table… light … open’. Damage limited to Broca’s area is relatively mild unless it extends to the neo-cortex to include sub-cortical structures which coordinate speech. Verbs are harder to say because they’re stored in the same cortical area as the area of controlling actions.

ii. Wernicke’s Aphasia Damage centres on the Temporal Lob area and like Broca’s aphasia the damage is mild unless it enters neighbouring areas. Speak fluently in well-formed and properly intoned sentences with proper linguistic conventionsl ike body language and turn-taking in conversation, but what they say lacks meaning and contains wrong/nonsense words. Eg. ‘Well this is… mother is away here working her work out a here to get her better, but when she’s looking, the two boys looking in the other part. One their small tile into her time here. She’s working another time because she’s getting to. So two boys work together and one is sneaking around here, making his work”. Have lost comprehension, understanding neither what the say nor hear.

iii. Anomic Aphasia Follows damage to frontal regions involved in the control of action. Damage to temporal lobe often results in anomia of nouns, so naming objects seems next to the region that recognises them, and inability to name colours follow damage to the posterior left temporal lobe near the occipital lobe which specialises in perception of colorus.  Has reasonable grammatical sentences but has difficult in finding words, hesitating and using indefinite nouns such as ‘thing’ and lose names for categories like fruits, animals and colours. Eg. ‘This is a boy and that’sa boy and that’s a thing. And this is going ot pretty soon. This is… a place that is mostly in’. It’s worse when naming out of usual context. So they might not say ’pen’ on its own but when shown a pad they’ll say ‘I don’t know what that is but you write on it with a pen’, and they might not know ‘pad’ but shown a pen they might say ‘you write on a pad with that thing’.

Wernicke’s aphasia The person cannot translate between thought and language. They can talk because Broca’s area still works, but what they say is meaningless. On the other hand, damage to Broca’s area causes speech loss, but Wernicke’s area of understanding remains.

Movement

Movement can be fully-automated (eg. heart pumping), semi-automated (eg. breathing), or manual (eg. writing letters).

Basal Ganglia One theory is that the BG is responsible for the force, direction, extent and duration of movement. Dysfunction in calculating the force needed to make a movement can result in failure to initialise (Parkinsonism), excessive initiation or overcompensation (showing grotesque facial agitation).

Primary Motor Cortex The highest motor sensor. Damage results in loss of skilled and delicate movements, because the pyramidal fibres controlling the hands originate in the motor cortex. But learning and memory of motor sequences are essentially unaffected by motor cortex damage, though a bit more clumsy.

Spinal Chord Covers reflexes like knee jerks, maintains muscle tone and posture, upright walking.

Hypothalamus If this is damaged, a mouse’s heart rate will no longer shoot up when it hears a sound of impending electric shock. But it still won’t press the lever that induces the shock. The lesion abolishes one reaction of learnt fear but not the other. If the shock then occurs without the sound, it goes back to high blood pulse.

Limbic System The ‘emotional brain’. Creates the experience and expression of emotions. Originally evolved to evaluate smells. Major elements include the thalamus, cerebral cortex, amygdala, hypothalamus, olfactory bulb and hippocampus.

 

*Emotions are involuntary

Sensory information travels first to the thalamus > cortext > amygdala. But there’s also a direct route from the thamalus > amygdala. The amygdala (which is part of the lymbic or ‘emotional resopnse’ system) responds emotionally to objects before the cortext has even experienced or recognised them, causing reactions like Figh or Flight Response (heart rate and blood pressure increase. Large muscled prepare for quick attention. Adrenaline). The thalamus

* Fact Of The Left-Hemisphere (LH) & Right-Hemisphere (RH)

Neo-cortext consciously thinks through a turn of events or conversation. The RH is specialised for facial processing. Your judgment is thus derived more from the left side of an image than its right.

LH is connected with more positive emotions. With RH is damaged, the person is prone to manic cheerfulness. RH is more prone to negative emotions. With LH damage, the person tends to develop depression. This is accentuating the true nature of either hemisphere.

LH is active for speech and comprehension.

RH damage results in repetitions of in speech, emotionless monotone speech, inability to understand less obvious features of language..

BEHAVIOURAL DYSYFUNCTION

LH/RH RH plays main role in perceiving others’ emotion. LH plays main role in interpreting logic. Damage to LH allows even greater perception of others’ emotions, even though they don’t understand what’s being said.

Ideomotor Apraxia Damage to the left parietal obe causes difficulty in making movements and gestures. It’s less severe when a tangible object’s present and the person’s required to use it, and most severe for symbolic gestures like greeting and saluting, and even more so when outside of the normal social context. So they’re not able to do voluntary movements that are unprompted by the environment.

MEMORY DYSFUNCTION

Amnesia From damage to the rhinal cortex in both hemispheres. Retrograde amnesia fogets everything after the accident. Amnesics view an abstract image and form a meaning of it. Later on, they’ll form the same way which means they remember “how to do it”, but deny having ever seen the picture before. Amnesics learn new how-to/procedural skills like typing as good as regular people. Seems the rhenal cortex processes memory for new episodes of experience but not memory for new know-how procedures.

Alzheimer’s Cell death primarily in rhinal cortex, but also temporal and parietal degeneration. Life exhibits symptoms of amnesic syndrome and other memory problems.

VISUAL DYSFUNCTION

Achromatopsis V4 is damaged so vision becomes monochrome. All memory and imagining of colour is lost as well, as colour no longer exists as a category of experience. If only one hemisphere suffers damage (unilateral damage), half the world appears in colour and half in monochrome.

Motion Blindness Damage to V5 causes seeing moving objects as a series of sill photos with discreet jumps (Like being high on ganja).

Object Agnosia Several types, eg. form agnosia, where the person sees colour, depth and contour but perceives only parts (eg. only top quarter and lower quarter of a bottle), not whole objects.

Simultagnosia Objects are perceived and recognised only one at a time.