Lawyers defending a woman whose baby died after being left in a hot car have told a jury not to condemn their client as a "child killer".

Jayde Poole, 29, has been standing trial in the Supreme Court for the manslaughter of her six month-old daughter Bella.

The infant died after Poole forgot to remove her from her car for more than two hours on a 30-degree day in Bendigo in December 2012.

In his closing arguments, lawyer Shane Gardner reminded the jury that the trial had heard evidence that Poole was widely regarded as a good mother.

"I ask you to pause to consider the significance of the decision you face, because the phrase 'child killer' of course has a very horrible ring to it," Mr Gardner said.

Mr Gardner said the prosecution case was weak when compared with cases where parents leave their children in cars to gamble, drink or take drugs.

"This is a case right down at the low end of scenarios you could conceive of where a child is left in a car," he said.

He said the case was a tragic and unfortunate accident, but it was not an instance where someone should be held criminally responsible.

"No one is more sorry for what happened than she is, and she will have to live with this for the rest of her lifetime."

"I urge you to set her free - set her free in the sense of her legal responsibility; because of course, you know she'll never be truly free."

Poole guilty of gross negligence manslaughter: prosecutor

However, prosecutors told the jury they should find Poole guilty of criminal behaviour.

Crown Prosecutor Nicholas Papas said Poole had failed in her duty of care to her daughter.

"Because... it is an absolute fundamental, in relation to a small child like this, that the first thing you do when you stop your car and turn the air-conditioning off, on a hot day, is to take the baby out of the car," Mr Papas said.

He said the case met the test of gross negligence manslaughter.

"The accused, Jayde Poole, failed to do what would be expected of a reasonable mother in her circumstances... It's got to be a gross breach," he said.

However, he acknowledged the case was not an easy one.

"All of us make mistakes. Anybody who has not made a mistake is not human, and we forget things, and we regret things, and terrible things sometimes happen," he said.

Mother suffered 'forgotten baby syndrome': expert

Earlier, a neuropsychologist from the US, David Diamond, told the court he believed Poole had suffered from a failure of memory that was consistent with similar cases worldwide.

As an expert witness for the defence, Professor Diamond said he was aware of more than 200 cases over 15 years of research in which children had died after being left in cars.

He called the phenomenon "forgotten baby syndrome".

He described to the court the way the competing memory functions of the brain can result in people forgetting new information while performing routine tasks.

"What seems to be happening in this case and in so many other cases is that the brain actually seems to fill in the memory gap," Professor Diamond said.

"What is very clear is that Jayde believed that Bella was safe and sleeping in her bedroom... the brain actually creates an alternative reality where the child must be safe.

"In those critical circumstances, having the sleep deprivation, being involved in some kind of routine, I believe any person is capable of forgetting a child in a car."

The jury will retire to consider its verdict tomorrow morning.