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Biology 202
2002 Second Paper
On Serendip

Schizophrenia: A Matter of Perception?

Sook Chan


The brain fills the pieces of information transmitted from the sensory environment that are not there or missing. For example, the blind spot in our eyes have no sensory light receptors, hence images focused on that spot are not transmitted to the brain. In fact, a hole should exist in our visual perception from the images projected onto our blind spot. This does not happen as our brain fills in the spaces with ongoing patterns that fit the image of our vision. Also, what we see and what is interpreted from what is seen spreads across a broad spectra from one individual to another. This indicates that there is no real format by which to generalize different individual's perceptions. Every input from the sensory environment is formatted and placed into context by our brain. Our brain organizes each situation into a format that makes sense to our schemata. So what happens when one's train of thought is fragmented and one's brain is unable to organize these fragments into a comprehensible pattern? Imagine if at times, your experiences become a slide show, fragments of experiences that do not come together. This is, in fact, how many people suffering from schizophrenia describe their experiences (1). Have you ever had an experience or a vision that just does not make sense? Maybe you might not understand the cause and the outcome of a certain experience or situation, but every memory is placed into context. Our brain makes sure of this. So, when seemingly unrelated fragments of information are sent to the brain, it attempts to combine these fragments together into a most logical manner. Is it possible that the reason that schizophrenics have an impaired sense of reality is because their brains logic is askew?

Schizophrenia is one of the most severe psychopathologies present today. Its causes are still vague, and the symptoms vary across a large spectrum. However, two generalized grouped of symptoms have been identified for schizophrenics: positive symptoms, and negative symptoms. Negative symptoms include lack of activity, anhedonia, and loss of interest. Positive symptoms include disorganized speech, hallucinations, and delusions experiences (1).

Individuals with schizophrenia commonly experience a disorder in their perception. Their surroundings are unreal and their external sensory environment seems different from what they previously knew. In fact, their perceptions become derailed; misinterpreting situations and the chronology of events. They are unable to distinguish between reality and imaginary. They have a false sense of reality and are unable to interpret the real context of situations. This could be due to the testimony that their experiences are fragmented. Does the brain put these pieces of fragments together, molding them to what is expected and most logical based on the limited contextual information?

"Everything is in bits. You put the picture up bit by bit into your head. It's like a photograph that is torn to bits in your head" (2).

Every experience from the sensory environment undergoes a processing mechanism where it is placed into two categories: something that has already previously been experienced, or an experience that is completely new. Our brain makes associations with the past, forming reactions and thoughts based on the past consequences and outcomes. It activates the schemata experiences (2). Ever smelled cotton candy and your brain immediately brings you memories of fairs and innocent bliss? However, schizophrenic individuals have difficulties in accessing their schemata. There is a lack of common sense in schizophrenic individuals which results from three interrelated problems experiences (2). They do not hold the same constant sets of beliefs about the world which we normally take for granted. They are unable to understand how other people feel or think about a particular matter. And their judgement about the likelihood of events is impaired. Their schemata, stored traces of earlier experiences, are impaired experiences (2). It has been suggested that during a psychotic episode, they are unable to control the contents of their consciousness because their input and output processes are not automatically supported by their cognitive schemata experiences (3). Yet, a study using PET scans found that during hallucinations, areas within the brain core were activated. The core regions served as meeting ground for thoughts, emotions, and perceptions, a place where present and past experiences may be compared experiences (3). One idea is that the brain creates and believes its own reality when the network core areas are activated. However, the same areas are also activated when a normal person sees and hears a real voice or incident. Is there a possibility that it isn't the inaccessibility of their past experiences that is of error, it is the error in circuitry that accounts for the impaired sense of reality experienced by a schizophrenic patient?

Fragmented sensory inputs may cause a flawed perception of situations. The different sensory inputs that make up an experience for normal individuals, are no longer interconnected for schizophrenic individuals. Also, schizophrenics have difficulties with memory due to poor organization in the encoding phase (2).

A common proof of skewed perception v. reality experienced by many schizophrenics involves extreme paranoia and the feeling of conspiracy against them. For example, a patient may see two people talking in hushed tones as he passes them on the street, and assume that they are conspiring against him. Experience is arbitrary. Two individuals may be presented the same painting, yet, they notice different things, Variation occurs in both what one chooses to see and what is interpreted from the things seen. Take the example above of a situation. He sees two people talking. Any normal person might ignore this incident, but the schizophrenic thinks that the individuals are talking about him. Yet, is the schizophrenic's perception flawed or just different from the average generalized reaction? Nonetheless, there is a definite problem with the way schizophrenics approach and interpret situations. Hallucinations and delusions are secondary conditions to the distortion of reality (4). One might say that hallucinations and delusions exists from the inability to correctly rationalize confusing situations by certain bits of information.

Patients with schizophrenia process irrelevant information that intrudes into their consciousness and causes distractibility. During a psychotic episode, the cognitive defect plays a major part. They are unable to organize inputs into a larger picture to provide context. Hence, schizophrenics fail to control the contents of their consciousness (2). The main question is what is the cause of this distractibility and flawed perception?

The prefrontal cortex and the hippocampus are the brain structures that are believed to be impaired in schizophrenic individuals (5). The prefrontal cortex elicits responses guided by internalized knowledge that include one's schemata and memory. The hippocampus stores memory and allows for its retrieval. It is the structural framework that provides the brain with a sense of context by binding together sites in the neocortex that represents the correct contextual framework (5). A strong correlation has been found between the prefrontal cortex physiological activation and the reduced hippocampus volume in schizophrenic subjects.

Much of the neurobiology of schizophrenia remains unknown. However, effective anti-hallucinating, anti-psychotic drugs such as clozapine target the dopamine receptors of the brain, indicating a possibility that dopamine D4 receptors may be a critical site of action (1). Auditory hallucinations are more common to schizophrenics than visual hallucinations. It has also been hypothesized that auditory verbal hallucinations arise from misinterpreted inner speech and aberrant activation of the primary auditory cortex (5). It has been summarized that the brain fills in the missing pieces of our sensory environment, making us see things that may not be there. A schizophrenic individual's brain is unable to correctly retrieve stored past experiences to format a current experience into context. Hence, the brain starts afresh, with no prior training of how to fill in the different fragments of sensory input. Schizophrenics experience an impaired sense of reality because as the brain is sticking the fragments of experiences together, it fills in pieces that are not there, making the individual believe in things that are out of context and out of reality.

"My perception of the world seemed to sharpen the sense of strangeness in things. In the silence and immensity, each object was cut off by a knife ... spaced off from other things. If you move it's frightening. The picture you had in your head is still there but it's broken up. If I move there's a new picture that I have to put together again." (2).

References

1) What Happens to the Body and Brain of Individuals With Schizophrenia.
2) Context and Cognition in Schizophrenia: Main source of my paper, very interesting as it covers many of the themes discussed in class.
3) Cause Identified.
4) Cerebral Activity Associated With Auditory Verbal Hallucinations: A Functional Magnetic Imaging Case Study
5) Impaired Recruitment of the Hippocampus During Conscious Recollection in Schizophrenia: Interesting article on the role of the hippocampus in memory and perception.


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