Kent Cochrane

Kent Cochrane (August 5, 1951 – March 27, 2014 ), also known as Patient K.C., was a widely studied Canadian memory disorder patient who has been used as a case study in over 20 neuropsychology papers over the span of 25 years. In 1981, Cochrane was involved in a motorcycle accident that left him with severe anterograde amnesia, as well as temporally graded retrograde amnesia. Like other amnesic patients (patient H.M., for example), Cochrane had his semantic memory intact, but lacked episodic memory with respect to his entire past. As a case study, Cochrane has been linked to the breakdown of the single-memory single-locus hypothesis regarding amnesia, which states that an individual memory is localized to a single location in the brain.

Early life Kent Cochrane was born on August 5, 1951, as the oldest of five children. He and his siblings grew up in the suburbs of Toronto, Ontario. After attending a community college to study business administration, he obtained a quality control job at a manufacturing plant, which he held until the time of his motorcycle accident. However, Cochrane was unable to remember emotional details of events from his past such as his brother's death and a dangerous fall he had at his home.

Cochrane also suffered from severe impairment of his autonoetic consciousness. This meant that he was unable to envision himself in the future. When asked what he would be doing later in a given day, month, or even a year, he was unable to respond with an answer. Just as he could not remember being physically involved with events from his past, he was unable to imagine future events. Ultimately, he lost any memory of his current actions once his thoughts were directed elsewhere. The trauma caused by Cochrane's accident left him with severe anterograde amnesia that has made it impossible for him to remember both new personal experiences and semantic information. As far as his temporally graded retrograde amnesia is concerned, he was considered an anomaly; in other words, his ability to recall events prior to the accident was dependent on when those events occurred. Although he could not remember personally experienced events, his semantic knowledge prior to his accident remained intact. For example, his recollection of factual information in math, history, and science, was unaffected.

Priming Priming studies on Cochrane revealed that individuals with severe amnesia can display intact priming capabilities regardless of episodic memory damage. Priming involves initially exposing a subject to a word or image so that a memory of that word or image can be formed. This is meant to improve a subject's recall of that word or image when that word or image is shown at a later time. Cochrane additionally showed that priming effects can last for long periods of time; in one study, researchers presented Cochrane with a list of words, and after 12 months showed him the same words with letters missing. Cochrane was able to complete these fragmented words as successfully as a person with normal brain function who was shown the same list initially. This challenged the previous opinion that patients with anterograde amnesia are incapable of adding information to their declarative memory. With respect to patient Cochrane, researchers found that successful priming is independent of both semantic and episodic memory. Episodic and semantic memory are therefore described as showing stochastic independence, ruling out the idea that Cochrane was able to retain information because certain words were of greater significance to him than others. The finding that interference significantly prevents successful semantic learning in amnesics provided explanation for why earlier experiments failed, as they did not make efforts to minimize interference. Nevertheless, Cochrane showed that severe anterograde amnesia does not restrict individuals from retaining knowledge that is more complex than information learned from priming.