Newcastle lost 3-2, with Dango Ouattara scoring the Brentford winner in injury-time.
Asked about the final whistle boos, Howe said: "It's not what we want. It is hard.
"But I don't blame the supporters for expressing their feelings. We created it ourselves to a point, with a lot of games where we haven't played as well as we can.
"We have defended poorly and we have been punished. There's no other thing to do but accept responsibility.
"There’s a harsh reality for me. I need to think long and hard about me. I need to work better and do more, work out solutions. I need to take full responsibility for what you see on the pitch.
"I always feel under pressure, so it’s irrelevant to me. The pressure I put on myself couldn’t be more extreme. I’m obviously not doing my job well enough."
Howe concedes Newcastle are in a major slump in the Premier League.
He also told ChronicleLive: "It’s a difficult moment for us, there’s no denying it. Today, especially, we look back at the run of games we had, and you can point to positives in the performance in defeat.
"You can say we created a lot of chances there, and on a different day that could be very different. Today we take full accountability.
"We are 1-0 up at home, and we should accelerate up the gears and show our true form. We didn't. It went the other way.
"Yes, there were mitigating circumstances. Yes, we are missing key players and yes some of our players are having to play while fatigued.
"But we have to be better, there is no other way to put it."