How to extract a particular object in a rodent brain

Hi, I have an image of a rat brain and I would like to extract the striatum from the image. Any suggestions on how to do this? I have attached an image for illustration. Str on the image implies striatum. I have tried thresholding, skull stripping, and k-means clustering but have not had any success. Thanks in advance

[Star Strider]

‘I have attached an image for illustration.’

Not yet.

Use the brown-framed green ‘picture’ icon to upload your image.

[Frank]

I thought I updated an image but did it wrong. Here is the image.

[Star Strider]

It’s a two-step process: 1 - ‘Choose file’, and 2 - ‘Insert image’.

[Frank]

Here is the file again

[John D'Errico]

Ah. I thought the rats just nibbled it away. :)