VISUAL PERCEPTION (DISORDER PART 2)

Spatial neglect also talked about as unilateral spatial neglect or hemi-inattention, that is a seizure to failing respond to events in the hemifield contralateral to a previous happened damage to the brain. The more common one of neglect is the visual neglect, which occurs to most patients after having a stroke. Patients tend to see only half of the world, depending on where in the brain the lesion is, e.g. the patient does not acknowledge the left side of the world, as he has right hemisphere damage in his brain. 

This is a classic example of a "copying" and
"spontaneous drawing" task by a patient with visual neglect
of the brain. In the copying task, it shows clearly, the denial
of the left world, and even in the spontanious drawing
task, the patient ignores the fact that there is a left piece to
his drawings.  

Patients that have spatial neglect “ignore” the other half of the world in a way that many experiments on measuring eye movements, line bisection, where the patient is asked to place a mark  in the centre of a straight line, here it is assumed that the patient with neglect, moves either more to the right, or when the lines are vertical, the patients drawings tend to move away from the body. Another experiment that has been done was, where the patient was asked to find all the Ts within a letter mix of Ts and Ls. The patient with the neglect on the right side does not know that the left side even exists anymore. Interesting is also the anatomy of the neglect as I believe that the parietal lobe not always played a critical role in human life. Research suggests that the parietal lobe actually nothing to do with the spatial neglect, researcher are more concerned with the temporal lobe and also focal lesions of the right inferior frontal lobe can lead to spatial neglect, therefore it can be said that the biological theories on where neglect actually takes place are controversial. Tests have been done on monkey’s brain that revealed that direct attention and eye movements to a three-dimensional target are linked with neuronal responses due to their dorsal visual stream, which is part of the parietal cortex that can be critical towards spatial action and vision, the same is expected in human individuals where lesions of the parietal cortex can be related with spatial deficits. Neglect is modulated. There is complexity of the visual scene and patients with lesions in their right hemisphere also have weakened recognition on their right side. 

In terms of the deepness of the hemineglect, there also dysfunction of memory in patients, where the patients where asked to look at a map from the cathedral in milan and describe what they see when looked at the front of the church, patients only described the right part of the map, then when the examiner turned the map around and asked the patient to describe what they see by looking at the cathedral from the back, they also described the right part, which i think is quit funny in terms of that, that is the actual side their brain " abandoned" before and never acknowledges that, that side even exists. also what i just realised, when a patient has a neglect for the left side, what happens when the patient would turn its head, wouldn't he than see what he actually missed the whole time, or is it like a circle that even though he does turn, his view on the world and what exists and what doesn't exists stays the same?  

Visual Perception (Disorder Part) Week 3

This week we evaluated the functional specialization of the brain and if our mind moves before our eyes do regarding the article by Treue and Martinez (2003). There are two main pathways that deal with our visual perception, the Parvo pathway deals with color and detail, such as what is this object i am holding, what type of color is it, so we know the definition of objects and faces too. also called object perception, lesions on that pathway can relate to visual agnosia. The second one is the Magno pathway, which deals with motion, we know through that how to navigate and also seen as the where pathway. Problems on this spatial perceptions pathway are optic ataxia, which are mutations in reaching and grasping. People with brain lesions, cannot put the name towards an objects straight away. Injury or mutation that is related to one specific part of the brain, affects the process of storing and releasing information. different experiments have been conducted to track exe movement, measuring the suppression in our visual system. These also record fixation, as when the participant looks at the picture, it records on what part of the picture the participants eyes are concentrating on. So it could be said that our attention filters our recognition and responds to it. It is like a concept of fluent energy when being conscious. Is there a limited capacity of attention we can observe or naturally have? As I imagend that our attention works like a memory card, and when things are not neccessary any more they are erased. However there are some attention impairments such as Agnosia and Memory loss. Agnosia is the impairment of recognition, its like "ignorance" of basic objects, due to injury in the brain. In visual agnosia the patient know that something is going on and an object there but its hard for them to place, identify and cannot see anything. Next week we will be talking about Prosopagnosia also seen as face blindness, where the essay question is on. 


I will now address some short answers to the questions that were discussed in the seminar to the article "cognitive Physiology: Moving the Mind´s eye before the Heads eye" by Treue and Martinez (2003). I also have read in the Neuropychology Textbook and some additional reading for this topic., with what i answered these questions. 


1. Why do we need to move our eyes across a scene? 
Our high spatial resolution is confirmed to a small fraction of the retrain, the fovea. This is a dedicated motor system, as we in general don't see everything at once. The retrain periphery covers a large amount of the visual environment and can monitor for high contrast, low spatial frequency and fast changing. 


2. Would it not be easier if we could see the whole scene at once?
Possibly yes, but implementing the foveal resolution abilities across the whole retrina, it would be enourmously stressful and very difficult resulting in the flood of information reaching the brain would be impossible to process, react and deal with the approaching situation at once. 


3. What does FEF mean? 
FEF means the "fractal eye field", an area in the frontal cortex involved in the generation, that coordinates the pointing and directing the eyes across one presented scene. FEF plays a central role in the directed spatial attention of the human brain and is directly linked  to the generation of eye movement commands when FEF is activated the eye movement is triggered. 

Neuroscience- the New Philosophy (Week 2)

The matter of neurology and psychiatry is coming more to light, all these different approaches show a different perspectiv such as the evolutionary theory, which has always been there, but only recent scientists approached this matter from the darwinian standpoint. Especially called as evolutionary neuro-psychiatry. I was wondering why this hasn't been approached before, MRI ad PET scan were found a long time ago and  scientists already knew than that the different scans can show the inactive/ active parts of the brain. A classic example used is that people with a classic psychological disturbance,such as Hysteria are seen with a mental illness, that illness is seen strictly medical, as the person developed a paralysis of his arm or leg, when you then test the patient in neurological terms, such as MRI or PET scans there are no deficits, nothing seems to be wrong, however where does these symptoms the patient claims to have, come from? Things like hysteria have been examined many many times, and mainly it is assumed that it comes from previous experienced emotional traumas that are impede him from moving arm or leg. So is that how we are going to explain mental illness these days? One particular word was stuck in my head for the last week, epiphenomenalism, which i didn't understand at first but than, it means that the individuals willingness in the brain is like a shadow that always accompanies you, but is never the cause. 

History of Neuropsychology (Week 1)

While reading the given article I was surprised how early past scientist were trying to understand the human skull with different procedures, such as Trephanation also seen as one of the first surgical procedures, to release evil spirits while cutting and chiselling the skull. The scraping method seems, even though healing and possible living longer for the patient quit serious. A few years back I took part as a visitor in one of my dad’s surgeries, how he was cracking the skull with professional instruments of one of his patients was impressive and so I cant imagine the pain and effort for everyone during such procedure and to the patients without any anaesthetic plus the healing process must be quit harming.  Another theory by the ancient Greeks suggested that the human heart was the main function of the body whereas every other organ was there to “cool” the heart. Pythagoras was one of the first to encounter that soul and major functions come from the brain. I do believe that ancient Greeks did a lot of research on behalf of previous found theories, as Hippocrates who was influenced by Socrates, he made up his mind of the imbalance of the body when the four humours (blood, black bile, yellow bile and phlegm) where not in balance. That is one of the first theories I had learned in high school about psychology and the influence of the brain. I learned and also experienced that humans like to identify themselves with one of the four humours and belief that the individual has more strength in one than another. We all know that neuropsychology bases on the relationship between brain function and the human behaviour, it is really interesting to read more about its history and how scientists managed to gain so much knowledge with such limited material. I have attached a table for those who like to have a look of the four humours, i think it is quit unbelievable that someone could come up with such theory. 

source: http://en.wikipedia.org/wiki/Humorism

Humour	Season	Element	Organ	Qualities	Ancient name	Modern	MBTI	Ancient characteristics
Blood	spring	air	liver	warm & moist	sanguine	artisan	SP	courageous, hopeful, amorous
Yellow bile	summer	fire	gall bladder	warm & dry	choleric	idealist	NF	easily angered, bad tempered
Black bile	autumn	earth	spleen	cold & dry	melancholic	guardian	SJ	despondent, sleepless, irritable
Phlegm	winter	water	brain/lungs	cold & moist	phlegmatic	rational	NT	calm, unemotional