The rationale for the essay will be to discuss how early childhood memories can contribute to Post Traumatic Stress Disorder (PTSD) later in adult life. Negative early experiences such as child abuse can have a major impact on the development of the brain. Similar to adults with PTSD, children have trouble sleeping, can not control their memories of the trauma and are constantly on alert (Kuafman, Plotsky, Meyerhof & Charney 2000). Memory alterations connected to PTSD represent a complex interrelationship between brain and mind (Wilson & Keane 2004).
The essay will therefore address a psychological and neurobiological approaches which have been typically associated with the diagnosis of PTSD. The psychological approach for discussion will be Freud’s(1896) psychodynamic model of neurosis which was one of the first paradigms to place emphasis on external stressor events (Wilson 2004). The essay will concentrate on the hippocampus, a brain area involved in memory and briefly discuss the amygdala. Saplosky (1996) neurobiological study in relation to stress, glucorcotoids and hippocampus, a brain area involved in memory functioning.
These brain areas will be discussed in relation to disturbing memories and deficits in memory functioning (Silver, McAllister & Yodofsky 2011). Firstly it will be necessary to discuss what the term “memory” means. A simple definition of memory would be a persons power to remember things or the faculty by which the mind stores and remembers information (Oxford 1964). A psychological definition is more complex and although memory is seen as a single term it refers to a multitude of human capacities (Medin & Pashler 2002).
There are three major processes involved in memory: encoding, storage and retrieval each operation represents a stage in memory processing (Sternberg 2009). Encoding is the process by which a memory is formed where information is changed into a useable form and stored in memory for later use (Nevid 2009). The information can be encoded in different ways; acoustically, iconic and semantically. Stored memories are quite often in the unconscious, implicit part of the mind and the retrieval process allows s to bring most memories back into the conscious mind (Sternberg 2009).
William James (1890) was one of the first to suggest memory was not a single system but rather comprises of a short and long term memory. James (1890) distinguished between primary memory as being conscious of what has just happened and secondary memory as the knowledge of events that have left our consciousness (Thorn & Page 2009). Hebb (1949) later supported James (1890) and suggested there was a neuro-physiological distinction between primary and secondary memory.
Hebb (1949) proposed primary memory reflects temporarily reverberating electrical activity where as secondary memory results from permanent synaptic change (Bernstain, Penner, Clarke-Stewert & Roy 2008). Waugh and Norman (1965) elaborated on James (1890) theory and proposed the multi-store model of memory. The multi-store model proposed verbal stimuli was perceived in the primary memory which had a very limited capacity. As new stimuli were considered and as the capacity of the primary memory was reached the stimuli were displaced and forgotten (Baine 1986).
However when stimuli was rehearsed it was either retained in short term storage in the primary memory or it was transferred to long term storage in the secondary memory. The more often information was rehearsed in primary memory the more likely it would be transferred to secondary memory (Baine 1986). Waugh and Norman (1965) model was extended by Atkinson and Shiffron (1968) they suggested that for information to become a memory it had to flow through a system. The system starts with the sensory memory or immediate memory associated with visual (iconic) and auditory (echoic) perceptual processing.
This is where information is first detected and if attended to will then enter the short term memory (STM). If the information which is now in the STM is rehearsed it will enter the long term memory (LTM). However if no rehearsal occurs the information is forgotten and lost from STM through the process of displacement or decay. The encoding or transferring of information into long term storage therefore depends on short term memory (Dehn 2011).
The psychobiology of learning and memory suggests that traumatic memory is uite different from ordinary memory and investigators such as Van der Kolk (1996) suggest symptoms of PTSD result from multifaceted nuero-hormonal changes that occur as a result of chronic stress. These changes can be accompanied by the release of adrenalin through the noradrenergic system which may play an important role in the enhancement of encoded, stored and retrieved information. PTSD can be defined as an incident where a person is exposed to serious threat of injury or death and experiences extreme fear (Shiromani, Keane & Le Doux 2009).
There are typically two types of memory disturbances identified in PTSD, intrusive memories and impoverish memory functioning (Mace 2000). Intrusive memories are events that are retrieved involuntarily and experienced as flash backs of the original trauma, and triggered automatically by situations that reflect aspects of the traumatic event (Mace 2000). Impoverish memory refers to diminished encoding or impaired retrieval abilities, and deficits in declarative memory. Fragmentation of memories may occur, both autobiographical and amnesic trauma related gaps in the memory, which occur for minutes to days and not due to ordinary forgetting.
In extreme cases it is suggested that extremely stressful experiences particularly in child hood maybe forgotten for a period of years (Friedman, Keane & Resick 2010). Human learning involves the interactions of memory systems mediated by distinct cerebral networks, of which can be divided into the declarative (explicit) or facts that can be assessed verbally and non-declarative, behaviours associated with emotional stiuations (implicit). These memory systems are mediated primarily by the hippocampus and amygdala, brain areas involved in learning, and emotional memory (Layton & Krikorian 2002).
There is interestingly a biological distinction between these areas which is mediated by structures outside the hippocampus. In the famous case of HM where damage to the hippocampus impaired declarative memory however non-declarative memory was unaffected (Scolvile, Milner 1957). The declarative memory can be split into two categories; episodic which stores specific personal experiences, such as remembering a first day at school and semantic; which stores factual information such as knowing the capital of France.
Freud (1893) early theory of neurosis known as “seduction theory” was one of the first to place emphasis on external stressor events, he suggested the symptoms could only be understood if they were traced back to a traumatic events specifically early child hood experiences of “ sexual” seduction or assault (Leys 2000). However it was not the experience itself which was traumatic but its delayed revival as a memory this was after the individual had reached sexual maturity and could therefore grasp its meaning (Leys 2000).
Freud (1893) drew upon the notion that childhood sexual experiences resulted is dissociation, denial, repression and other primitive defence mechanisms (Friedman, Keane & Resick 2007). Freud (1893) suggested that during development a child could potentially experience a range of traumatic events. As a result the victim typically uses repression an “ego” defence to suppress traumatic memories and once in the un-conscious or implicit mind, neurotic symptoms might occur as a result of active forces being applied to the un-conscious or explicit memory (Wilson & Lindy 2004).
The repressed memories do not change when they are retained in the un-conscious (implicit) memory and will emerge via the activation of situational reminding cues (Wilson & Lindy 2004). His theory however was not well received in Conservative Vienna and he revised the seduction theory in 1896, he concluded that the memories of his patients may have in-fact been fantasies and have their origins in the libidinal drives and conflicted attachments to parental figures ( Mason 2003).
Freud’s early thinking regarding trauma was largely based on children as sexual beings from birth onwards, and that this sexual instinct was based on libidinal forces that could lead to intra-psychic conflict: the Oedipal complex (Mason 2003). This led to psychodynamic theory, a complementary approach emphasising unconscious influences on issues related to memory and PTSD, and seeing suceptability as a result of factors like poor childhood relationships, insecure attachments & sexual abuse (Friedman, Keane & Resick 2010).
Current empirical data however clearly supports Freud’s (1893) original theory regarding the psychological impact of child abuse and as a result children have been shown to suffer from PTSD and symptoms associated with cognitive, emotional and behavioural development (Deblinger, McLeer, Atkins, Ralph & Foa 1989). Current research has brought into debate Freud’s (1897) suspicions of imaginary fantasies, the recovered memory/ false memory debate” brings such childhood memories into question.
The theory suggests child hood memories are not reliable and it is relatively easy to plant memories for events that did not really occur through ideas suggested by over enthusiastic therapists the media or self help books related to sexual abuse (Pezdek & Banks 1996). Hyman and Billing (1998) conducted a study to investigate if students would create false child hood memories. The study found approximately 25% of students created false childhood memories after being encouraged to imagine the suggested child hood event (Hymann &Billing 1998).
A study by Clancey, Schacter, McNally & Pitman (2000) also pointed to gender bias in relation to false memories, they used the Deese/Roediger-McDermott paradigm using four control groups of women. The study found women with PTSD had a higher rate of false recognition of critical lures than women with abuse histories without PTSD, non abused non PTSD women, or men with out abuse or PTSD (Bremnar, Krause, Shobe & Kihlstrom (2000). Women with PTSD were also found to have poorer memory for previously studied words, which is consistent with the findings of declarative memory deficits in PTSD (Bremnar et al 2000).
Studies such as Sapolsky (1996) have led to the idea that external stressor events could have a profound impact on the biology and behaviour of organisms. Just as Freuds theory suggests, external stressor events have an impact on triggering unconscious implicit memories through their retrieval via situational cues. Neuro biological studies have shown retrieval is accompanied by adrenaline release which may further aggravate the traumatic memory (De Kloet, Oitzl & Vermetten 2008). The noradrenergic system is responsible for the “fight or flight” rapid response to stress.
This is associated with increased firing of noradrenalin neurons in the brainstem which enhance the release of noradrenalin in the brain and strengthens memories connected to emotional events (Bremner, Krystal, Southwick & Charney 1996). Cahill and McGaugh (1998) suggest adrenaline is shown to enhance the memory in a “dose dependant way”, it seems to enhance retention thorough its effects on the limbic structures, including the amygdala complex. There fore when a stressful event is experienced adrenaline is released, the noradrenergic system may then play an important role in the enhanced encoding of trauma related memories.
The accompanied release of adrenaline when a traumatic event is experienced may further strengthen the traumatic memory trace. A positive feed back loop may then result in deeply engraved memories, which are expressed as intrusive recollections and flash backs (Cahill & McGaugh 1998). Child abuse and other stressor events can have lasting effects on the hippocampus, the brain area involved in declarative, implicit, unconscious memory. The hippocampus is part of the limbic system, and part of a group of structures that surrounds the brain stem.
These structures play an important role in the experience of emotions motivation and memory (Litwack 2010). Sapolsky (1996) conducted studies on rats in his Stanford University laboratory, he concluded that glucocorticoids can cause rats brains to shrivel as the dendrite branches that communicate with other neurons wither away. Sapolsky, Romero, Munk (2000) found prolonged exposure to stress causes irreversible damage in rats, the findings therefore suggest long term exposure to glucocorcitoids in humans with PTSD may also result in permant nueron damage to the hippocampus and deficits in declarative memory.
Further neuroimaging studies have found smaller hippocampus volume in people with PTSD, this was found in MRI imaging of Vietnam veterans and adults with a history of child abuse relative to healthy comparison subjects (Francati, Vermetten & Bremner 2007). The subject and theory which has been discussed far exceeds the parameters of this essay, however the greatest attempt has been made to cover as much of the subject as possible.
It would seem there is mounting evidence to support Freud’s (1893) original “seduction theory” that early traumatic childhood experiences can lead to memory disturbances later in adult life. Memories have been found to be engraved even deeper by the noragenric system and the increased release of adrenaline caused by exxecive stress associated with PTSD. Sapolsky (1996) and Sapolsky, Romero, Munk (2000) have further discussed the impact of stress on the brain and effects on the hippocampus an important structure in the functioning of memories.
Nueroimaging has further shown shrinkage in the hippocampus in adults whom have been diagnosed with PTSD and have experienced a history of child abuse. There has however been studies by hyman and billing and Clancey, Schacter, McNally & Pitman (2000) that suggest some memories can be planted or imagined, via the influence of media and other factors, and a gender bias concerning deficits in declarative memory. However with scientific evidence it would seem early childhood trauma could result in PTSD later in adult life.
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