Our Brains, Our Selves: An excerpt from the new book by Dr Masud Husain

‘So, what brings you to see me?’ I asked.

.

She looked around the consulting room, averting her gaze.

‘I’m not sure how to put it, or even if you’re the right person to see, to be honest.’ Anna responded with a shy smile, pushing her straight auburn hair back over her narrow, freckled face.

‘Tell me what the problem is and I can see if we can help.’ I offered her a reassuring look. She studied me carefully, fixing me with her wide, dark hazel eyes, as if contemplating whether I might be someone she could confide in. Eventually she spoke, now in a much softer, slightly tremulous voice.

‘It’s a bizarre thing to explain to someone, but my right arm and leg have been acting kind of strangely.’

‘In what way?’

She hesitated. ‘I can be reading in bed and suddenly realise that I don’t know where my right hand is, but if I look at it, it will be there. The same can happen with my right leg. I can be sitting on the bus and become unaware where it is. Before I know it, someone has tripped over my foot because it is in the middle of the aisle.’

‘How long have you been experiencing these symptoms?’

‘Probably for the last six months, but I hadn’t really thought too much of them. I just thought I wasn’t paying enough attention and that it wasn’t anything to worry about. But I’m noticing it more now.’ She nodded, apparently gaining more confidence in explaining the reason she had come to see me.

‘And it’s only your right arm and leg?’

‘Yes. I’ve never experienced anything like that on my left side.’

‘Tell me a bit more about when you become aware of these symptoms. What are you doing?’ ‘It can happen anywhere if I’m busy doing something.’ Her voice was stronger now. ‘Suddenly I realise that I don’t know where my right hand or foot is. But, like I said, if I look at them, there isn’t a problem. If I’m not looking at them . . . well, I kind of lose them. I am getting a bit worried about it because it’s now also affecting my dancing.’

‘Dancing?’

‘Yes, I love to dance.’ She smiled. ‘I joined a club a year ago. We do all sorts of ballroom dances. It’s my big hobby. I absolutely adore dancing and spend any free time I have practising. I’m hoping to enter competitions at some stage, but that’s not the important thing. I just really enjoy it.’ She beamed. It clearly did mean a lot to her.

‘That’s good to hear,’ I said, ‘but how is your dancing being affected?’

Anna’s face turned a vivid grapefruit pink. Her lips gripped together in obvious discomfort. Whatever it was, her demeanour had suddenly changed.

Eventually she blurted out, ‘I know dancing isn’t a serious thing but it’s where this first happened.’

I nodded, not really knowing what she was about to say, but giving her the space to articulate it without interruption.

‘Because I don’t know where my right hand and leg are when I’m dancing, it can be awkward with my dance partner . . .’ She trailed off, now pursing her lips even more tightly. ‘In what way?’ I asked gently.

Anna’s face contorted into a grimace as she shifted uneasily on her chair. ‘Well, sometimes my right leg will wrap itself around his leg and bring us far closer than we should be, if you see what I mean.’

‘I see, and what’s happened then?’ I asked.

‘Well, it’s really embarrassing. It’s one thing not to know the dance steps and mess things up. But it is completely different if it looks like you’re coming on to a man on the floor, in front of everyone. One of my dance partners, who I really like, is now reluctant to dance with me anymore. God knows what he thinks of me. But there’s another one who’s become super keen because he’s got the impression that I’m interested in him. I’m not, but either way, it’s awkward.’ She looked disconsolate, her eyes pinned to the floor in apparent shame. A silence fell over the room.

‘That must be very difficult,’ I said. ‘How long does it take for you to “lose” awareness of where your arm or leg is if you don’t look at them?’

She looked up, grateful to be asked a question.

‘I’m not really sure.’

‘Shall we try now?’ I asked gently.

‘Alright, but what do you want me to do?’ She glanced at me, quizzically.

‘I’d like you to look at your right hand. Good, and now look away. Tell me when you start to feel that you don’t know where it is.’

It took about twenty seconds before Anna said that her right arm began to fade from her awareness. But the moment she looked at it again, it ‘reappeared’. The same also occurred with her right foot when we tested that.

Perhaps she had some unusual sensory loss I thought, but it was odd that her symptoms were confined to only the right arm and leg. I performed the neurological examination – including simple sensory testing of touch, temperature, vibration or proprioception (where she felt her limbs were) – but found nothing abnormal. The only difficulty Anna had was working out what object I placed into her right hand when her eyes were shut. Even without vision, by moving our fingers over an object (a process sometimes referred to as active touch), most of us can normally differentiate between objects such as various types of coin, or a key, or an eraser. But although Anna could do this easily enough when I placed those items in her left hand, she was very unsure what the objects were when using her right hand.

Over a century ago, neurologists in Europe had become aware that such an impairment in recognising objects by touch was usually associated with damage to the parietal lobe on the side of the brain opposite the affected hand. Later, in Montreal, the neurosurgeon Wilder Penfield developed a technique to directly, electrically stimulate the exposed surface of the cerebral cortex of awake patients who were being operated upon for epilepsy. By using this method he was able to map out both the primary sensory and motor representations in the human brain, in order to avoid damaging these regions when he performed the surgery. His painstaking work revealed how sensations from different parts of the body were located in a systematic, topographical manner in the anterior part of the opposite parietal cortex (left parietal cortex for the right side of the body, and vice versa). This is sometimes referred to as a homunculus (a little version of a body). Penfield found that more cortex is devoted to those parts of the body with the greatest sensitivity to touch, such as the face, tongue and hand. These parts of the homunculus are allocated more space in the cortical representation.

When this part of the parietal cortex is damaged, appreciation of sensory information from the opposite limbs can be impaired. In Anna’s case, though, it was not simple sensation such as touch that was lost in her right hand, but an inability to integrate the information from touch receptors in the skin with the moving position of the fingers. In the 1950s, Derek Denny-­Brown, who worked at Queen Square before becoming Professor of Neurology at Harvard, proposed that the function of the parietal cortex goes beyond simply registering the sensations on the skin. By spatially ‘summating’ different types of tactile information as the fingers move over an object, a critical function of the parietal cortex, he argued, is recognition of the form of an object – which he termed ‘morphosynthesis’. When this is impaired, a patient might suffer from ‘amorphosynthesis’, or an inability to perceive the shape of an object placed in the hand opposite to the parietal damage. ‘Which side of the skull did you have your burr hold drilled?’ I asked Anna.

‘This one. This is where they did the operation.’ Anna pointed to the left side of her head as she pulled away her hair to show me an indentation the size of a coin, high up on the back of her skull over her parietal lobe. It was difficult to believe that it was a coincidence that she was now experiencing a loss of awareness of her right arm and leg when these limbs would correspond precisely to the location of her previous surgery. I was contemplating the possible causes of this phenomenon, when Anna softly asked, ‘So you believe me?’

I was taken a little aback. I had not thought I had given her any reason to think otherwise, but clearly she had been worried that her story might have sounded far-­fetched. ‘I have to say that honestly I’ve never had a patient who has come to me with quite the symptoms you are experiencing – but, yes, I believe you. I think we have to look into this a bit more.’ ‘Thank you,’ she said with obvious relief. ‘I didn’t know whether anyone would take me seriously.’

(Excerpted with permission from Our Brains, Our Selves: What a Neurologist’s Patients Taught Him About the Brain, by Dr Masud Husain, published by Canongate; 2025)